( ) 1/2 ( ) : 2.67 M Y : 454,586 : 3.81 M Y : : 6.48 M Y : 454,586 : : : :,,, TLD,, : /,, ( 5 ) Radiation therapy, therapy radiation dose verification and evaluation, : absolute measurement, TLD, chemical dosimetry, traceability ( 500 ) 260 1. / ( 5 % ) ( X- ) / 2. TLD ( 5% ) TLD ( 20 MeV ) / ( 20MeV ) / (±3 % ) (±3% ) 3., /..
I. II.. ( 3 ). 50,.. / /. 1) /, 2) ( X- ) /.
III.. 1. / / - - System - 60 Co - X- - Fricke (Ferrous Sulfate) Dosimeter - Spectrophotometry system - FeSO 4 generator 2. TLD TLD ( 5% ) TLD dosimetric TLD dopants 3 3. / TLD ( 20 MV )
IV. 1 / - - PC data acquisition 60 Co - core bridge differential voltage output calibration - 60 Co core bridge differential voltage output core 60 Co X- - X- - Fricke Dosimeter - Fricke Dosimeter system - Fricke Dosimeter - Fricke Dosimeter - 60 Co Fricke 2 TLD, LiF:Mg,Cu,Na,Si TL KLT-300(LiF:Mg,Cu,Na,Si) TL.,,,,,,
,. LiF, Mg : 0.2 mol%, Cu : 0.05 mol%, Na Si : 0.9 mol%. 830. TL, TLD TL. TLD TLD., LiF:Mg,Cu,Na,Si(MCNS) LiF:Mg,Cu(MC) ; LiF:Cu,Na,Si(CNS) ; LiF:Mg,Na,Si(MNS),. TL 300-800 nm, TL 3. Mg Mg Mg. TL, Cu 385 nm 355 nm, Cu 355 nm 405 nm. Cu 385 nm. Na Si. LiF:Mg,Cu,X TL X X TL. KLT-300 TL TLD-100(LiF:Mg,Ti) 30, 30 Gy. LiF:Mg,Cu,P 73 kev 118 kev. 10 TL 0.0054.
70 ngy. 3... ICRU 5 %..,. /.. (, W/e S w,air ) (, P u, k m k att ) IAEA 277., K air, N D,air ( N gas ), D w, D w. Co-60 N k D w., IAEA 398., TLD
KLT-300(LiF:Mg,Cu,Na,Si, Korea), GR-200((LiF:Mg,Cu,P, China) MCP-N((LiF:Mg,Cu,P, Poland) 3 TL 1.25 MeV(Co-60) 21 MV (Microtron). IAEA/WHO TL (element correction factor (ECF)) TL. Co-60 20 MV. TLD. 4 Physicist / 11. V. 02. 4. 1 05. 2. 28 3. 1. /. Hardware 100 %. /,,.
2.. 3. / / 4., KAERI
SUMMARY I. Project Title Development of evaluation and performance verification technology for radiotherapy radiation II. Objectives and Necessity of the Project No matter how much the importance is emphasized, the exact assessment of the absorbed doses administered to the patients to treat the various diseases such as lately soaring malignant tumors with the radiotherapy practices is the most important factor. In reality, several over-exposed patients from the radiotherapy practice become very serious social issues. Especially, the development of a technology to exactly assess the high doses and high energies (In general, dose administered to the patients with the radiotherapy practices are very huge doses, and they are about three times higher than the lethal doses) generated by the radiation generators and irradiation equipment is a competing issue to be promptly conducted. Over fifty medical centers in Korea operate the radiation generators and irradiation equipment for the radiotherapy practices. However, neither the legal and regulatory systems to implement a quality assurance program are sufficiently stipulated nor qualified personnel who could run a program to maintain the quality assurance and control of those generators and equipment for the radiotherapy practices in the medical facilities are sufficiently employed. To overcome the above deficiencies, a quality assurance program such as those developed in the technically advanced countries should be developed to exactly assess the doses administered to patients with the radiotherapy practices and develop the necessary procedures to maintain the continuing performance of the machine or equipment for the radiotherapy. The QA program and procedures should induce the fluent calibration of the machine or equipment with quality, and definitely establish
the safety of patients in the radiotherapy practices. In this study, a methodology for the verification and evaluation of the radiotherapy doses is developed, and several accurate measurements, evaluations of the doses delivered to patients and verification of the performance of the therapy machine and equipment are conducted. With these conducts, not only the socio-economical losses by the patients from the maladministration of the radiotherapy doses could be greatly reduced but also huge benefit to them from the enhancement of the quality of life, which is more than the monetary value be brought. To achieve these goals, two ultimate objectives are set up and the study is conducted 1) to develop a technology for the evaluation of the high absorbed doses and high energies administered to the patients and the performance test of the radiotherapy machine and equipment and 2) to fabricate the calorimeters or chemical dosimeters for the absolute measurement of the absorbed doses (from gamma rays and high energy x-rays) in the radiotherapy practices, to establish the standards for the evaluation of radiotherapy doses and to verify an internationally acknowledged traceability of the performance of the machine and/or equipment. III. Contents and Scope of the Project The contents and scopes of the study conducted to achieve the objectives are as follow: 1. Development of absolute measurement technology and chemical dosimter for high energy/high dose radiation Development of absolute measurement technology for high energy/high dose radiation - Construction of graphite calorimeter and evaluation of its characteristics - Development of absorbed dose measurement system and performance evaluation - Absolute measurement of absorbed dose for 60 Co gamma-ray and participation in international key comparison - Development of application technology to high energy X-ray used in the
medical or industrial area Development of Chemical Dosimter - Design of Concept for Fricke Dosimeter - Development of Spectrophotometry system and Performance Evaluation - Construction of generator for FeSO 4 solution and evaluation of its characteristics 2. Development of the thermoluminescence dosimeters (TLDs) for the measurement of radiotherapy doses and improvement in the performance characteristics of the TLDs Development of the top notched TLDs in the world, Conduct of the performance test of the TLDs developed for the measurement and evaluation of the radiotherapy doses, Evaluation of the dosimetric characteristics for the TLDs developed and Analysis of the 3-dimensional effects from the dopants in the TLDs developed. 3. Development of the methodologies for the calibration and evaluation of the doses delivered from the radiation therapy machine and equipment Establishment of the methodologies for the dose assessment and calibration of the radiation therapy machine and equipment, Setting-up of the methodologies/procedures for the irradiating patients with the radiation therapy machine and equipment and fabrication of the irradiation phantoms, Establishment of the traceability in the measurement of doses from the radiation therapy machine and equipment and conduct of the practical verification experiments, Establishment of the measurement values for the calibration factors of the TLDs for the photons with energy of up to 20 MeV and Conduct of the practical assessment of the radiotherapy doses with the several radiation therapy machines and equipment at several hospitals and medical centers.
IV. The Project Results 1. Development of Absolute Measurement Technology for High Energy/High Dose radiation and Chemical Dosimeter Construction of Graphite Calorimeter and evaluation of its characteristics - Construction of Graphite Calorimeter - Completion of absorbed dose measurement system and development of data acquisition and analysis program with PC interfacing. Development of Absolute Measurement Technology of Absorbed Dose for 60 Co gamma radiation - Measurement of temporal behavior of differential voltage output in core bridge with supply of accurately known electric energy and calibration of energy in calibration run - Measurement of temporal behavior of differential voltage output in core bridge for 60 Co gamma radiation in radiation run Absolute Measurement of absorbed dose to graphite for 60 Co gamma radiation and evaluation of its uncertainty Development of Application Technology to high energy X-ray used in the medical or industrial area - Set up a design criteria of high energy X-ray measurement system using LINAC Development of Chemical Dosimeter - Design of Concept for Fricke Dosimeter - Set up of Fricke Dosimeter system and Characteristic Evaluation - Preparation Procedure of Fricke Dosimeter and Cleaning Procedure of vessels used for preparing Fricke Dosimeter - Preparation of Fricke Dosimeter and evaluation of its characteristics - Measurement of absorbed dose to Fricke solution for 60 Co gamma-ray and analysis
2. Development of the thermoluminescence dosimeters (TLDs) for the measurement of radiotherapy doses and improvement of their performance characteristics In this study, by the investigation of the optimum conditions for the production of the (LiF:Mg,Cu,Na,Si) TL materials, KLT-300 (LiF:Mg,Cu,Na,Si) TL detectors are developed for the medical and personnel radiation dosimetry, and the study of the roles of the dopants in the KLT-300 (LiF: Mg, Cu, Na, Si) TL materials is conducted. The fabrication of the TL detectors consists of six processes such as the preparation of the raw materials, mixing powders, activation of the materials, pelletizing with compression, sintering and annealing, and in each process various parameter values should be precisely controlled. Particularly, the concentration of the dopants doped to the LiF, base-material, is the most important parameter, and the optimum concentration is estimated as Mg of 0.2 mol%, Cu of 0.05 mol%, Na and Si of 0.9 mol%, respectively. Also the optimum sintering temperature, which is the critical parameter value in the sintering process is estimated as 830. Because the characteristics of the TL materials depend on the impurity levels in the forbidden band of the materials, it is very important to select the right additive impurity materials in order to materials having the characteristics of the TL materials pertinent to being used as the TLDs. Thus, the investigation of the roles of the dopants is able to provide very useful information to the study of the performance enhancement of the TLDs or development of new TLD materials. For the study, optimized samples such as LiF:Mg,Cu,Na,Si (called MCNS) and few samples with excluding some dopants such as LiF:Mg,Cu (called MC); LiF:Cu,Na,Si (called CNS) and LiF:Mg,Na,Si (called MNS) are fabricated under the same conditions, and the glow curves of these samples, which represent the total quantity of the luminescence, are measured. Also, in order to obtain the information of the luminescence center, the 3-dimensional TL data of the TL intensities according to the temperatures and wavelengths are collected and analyzed with comparison of the differences among them. Samples containing magnesium represent the almost similar values in the peak
numbers of the glow curves and temperatures at the individual peaks. While, in case of the samples without magnesium, the glow curves completely differ from those of the samples with magnesium, and magnesium is judged to be directly involved in the formation of the trap levels. From the results of the TL spectrum analysis, the emission with a wavelength of 385 nm in case of the samples containing copper is dominant, while the emission with a wavelength of 355 nm is weak but observed. In case of the samples without copper, the emission with a wavelength of 355 nm is weak but still observed, and emission with a wavelength of 405 nm is dominant. From these study results, copper is judged to play a role of the luminescence center, which is mainly associated with the emission with a wavelength of 385 nm. Also, sodium and silicon are known to be not directly associated with the luminescence center. From the above conclusions, the study suggests the possibility of the enhancement of the TL characteristics through the changes in the dopant element, X since the element X plays an assistant role of increasing the luminescence efficiency in LiF:Mg,Cu,X type TL materials. The sensitivity of the KLT-300 TL detector is thirty times higher than that of the TLD-100 (LiF:Mg,Ti), and the linearity response to the doses is linear up to the dose of about 30 Gy, and above the dose of 30 Gy, the curve is found to represent a sub-linear response. In case of the energy response, the KLT-300 detector represent more enhanced energy responses in the energy range at 73 kev and 118 kev than compared to that response from the LiF:Mg,Cu,P material. Regarding the reproducibility of the TL detectors, when the detectors are used by ten times, the coefficient of variation for the TL luminescence amounts to the same doses is found to be 0.0054 and excellent. The lower limit of dose detection is found to be about 70 ngy. 3. Development of the calibration and verification methods for radiation therapy system The high doses of radiation to be delivered to the patients are required to have high accuracy in practice in radiation therapy. The data required to achieve better
accuracy in the determination of the radiation dose delivered to the patient are available because the anatomical information obtained from sophisticated diagnostic imaging procedures are improved. It is clear that the success or failure of radiation treatment depends on the absorbed dose delivered to the tumour and this should be in a few percent from the described accuracy. So ICRU concludes that an accuracy of the ±5 % in the delivered dose to patients is needed, and the other research indicated that an even better accuracy is needed. This means that the overall uncertainties in radiation dosimetry should be minimized and the determination of the absorbed dose from the radiation beams should be improved the accuracy. The calibration of the radiation beam used for radiation therapy is needed the several complicated measurements and application of the several correction/ conversion factors. Therefore it is important that unambiguous procedures in the every step of the calibration are specified and practices of the calibration can be done with minimum difficulty. So this report described the calibration procedures using current physical data(e.g. W/e and stopping power) and correction factors (e.g. P u, k m k att ) to determine the absorbed dose from a radiation beam based on the IAEA Technical Report 277. But the various steps between the calibration of ionization chambers in terms of the quantity air kerma, K air, at the standard dosimetry laboratories and the determination of the absorbed dose to water, D W, at hospitals using dosimetry protocols based on the factor N D,air, introduce undesirable uncertainties into the measurement of D W. Many factors are involved in the dosimetric chain that starts with a calibration factor in terms of air kerma measured in air using 60 Co beam and ends with the absorbed dose to water, D W, measured in water in clinical beams. Uncertainties in the conversion of N K to N D,air mean that in practice the starting point of the calibration of clinical beams already involves a considerable uncertainties. Therefore the calibration methods to determine the absorbed dose directly from a radiation beam based on the IAEA Technical Report 398 are described in detail. After the measurements of the calibration factors for the ionization chambers are conducted with the technical support of Korea Institute of Radiological Applications in Medicine (KIRAM), the dose correction factors for the measurement by the TLDs are
obtained. And to verify the effectiveness of the calibration for the radiation therapy beams, the energy responses to photons with energies from 1.25 MeV of 60 Co to 21 MeV of Microtron for three kinds of TL elements such as KLT-300 (LiF:Mg,Cu,Na,Si, made in Korea), GR-200 (LiF:Mg,Cu,P, made in China) and MCP-N (LiF:Mg,Cu,P, made in Poland) are measured, respectively. The International Atomic Energy Agency (IAEA) and World Health Organization (WHO) conduct the verification of the calibration of the radiation therapy beams with using the TL powders. However, in this study, the element correction factors (ECFs) for the TL elements are able to be precisely derived, and TL elements, which are easy to handle with compared to the TL powders, are used for the calibration. Also, other investigators mainly conduct the measurement studies for the energy reponses up to those of 60 Co but, in this study, energy response measurement studies for the high energies up to 20 MeV, which are used in many radiation therapy practices, are conducted. At last, using the TLDs developed by and solid phantoms fabricated at KAERI, the dose assessments for the several radiation therapy machines and equipment at a few hospitals around the country are conducted. The dose assessments for the hospitals in the four different regions and after distinguishing the hospitals from whether they employ in-house medical physicists or not where a total of eleven hospitals or medical centers selected around the country are conducted. V. Plan for the Application of the Project Results The expected outcomes and application plans for this study, which have been obtained during the period of 1 April 2002 until 28 February 2005 are as follow: 1. Economical Aspects The technology for the calibration and verification of the high energy/high dose, which this study aims at developing, is currently the one of the hottest areas that concentrate efforts and money are given and invested for the applications of the dose measurement in medicine and spacecrafts around the world. It is
expected that if the establishment of the necessary technology through this study and installation of the necessary large scaled machines and equipment at the national calibration laboratories are accomplished, then, these would greatly contribute to the development of the technology of the precision industry and economy in Korea. The technology for the hardware fabrication through this study would be able to be established by itself to a maximum by 100%. In the future, if the high energy/high dose generating machine and equipment are developed through the continuing investment and studies, the manufacturing technology of the radiation generating machines and equipment in Korea would be graded up to the level of technically advanced countries. Then, it is expected that the technology would be greatly contributed to the economically enormous spreading effects on the areas such as medicine, electronics, machinery, precisional instrumentation. 2. Social Aspects Providing a methodology of the simple but convenient and accurate dose assessment to many forefront radiation therapy institutions in the country and establishing a system of the radiation therapy assessment at the same level of the technically advanced countries, Establishing the homogeneity in the administered doses to the patients among the radiation therapy practice institutions, Inducing the correct calibration of the radiation therapy machines and equipment by the accurate assessment of the to be administered doses to the patients in the radiotherapy practices at hospitals and establishing the safety of the patients and Establishing the public acceptance or trust for the radiation safety through the precise and exact assessment of the administered doses to the patients in the radiotherapy practices and continuingly verifying the performance of the therapy machines and equipment.
3. Technical Aspects Providing an infrastructure for the installation of the large scaled high energy/high dose standard irradiation equipment and facilities and research studies in the future, Providing an infrastructure for the assessment of radiation therapy doses, calibration and verification of the machines and equipment, Providing the measurement services for the therapeutic radiation doses to the institutions and hospitals who practice the radiation therapy to the patients with the photon and electron beams with various energy values, By extending the study results to the general industry, applying them to the national dosimetry standards for the high energy/high dose radiation generating machines and equipment at the industry sector and Applying the results to the national standards to establish the internationally acknowledged traceability system for the radiation therapy doses and to the foundation of the quality assurance and control programs for the radiation therapy doses. 4. Contributions to Other Industry and Other Aspects Providing the foundation data to prepare the legal and regulatory system for the operation of the national quality assurance and control programs in the medical sector and Extending the use of thermoluminescence dosimeters developed by KAERI to the radiation therapy dose assessment in medicine.
CONTENTS Summary viii Contents xviii List of Tables xx List of Figures xxii I. Introduction 1 II. Research and development status 3 III. Details of the study and the results 1. Development of absolute measurement technology for high energy/high dose radiation and chemical dosimeter 5 1) Development of absolute measurement technology for high energy/high dose radiation 5 2) Development of Chemical Dosimeter 60 2. Development of the thermoluminescence dosimeters (TLDs) for the measurement of radiotherapy doses and improvement of their performance characteristics 81 1) Production of KLT-300(LiF:Mg,Cu,Na,Si) TL detector 81 2) Impurity analysis and XRD analysis 87 3) The roles of the dopants in the KLT-300(LiF:Mg,Cu,Na,Si) TL detector 91 4) TL glow curve deconvolution 104 5) Dosimetric properties of the TL detector 106 3. Development of the calibration and verification methods for radiation therapy system 117 1) Absorbed dose determination in photon based on air kerma 117 2) Absorbed dose determination in photon based on standards of absorbed dose to water 150 3) Verification and evaluation of the radiotherapy radiation dose 197
IV. Achievement of project objectives and contribution to other development 220 V. Proposals for application of the results 23 VI. References 225
List of Tables Table 1-1. Heat Capacity of bare graphite and each impurity in Core. 26 Table 1-2. Radiation chemical yield of free radicals and molecules for several radiations. 61 Table 1-3. Characteristics of purified water produced by millipore purification system. 68 Table 1-4. Result of mass spectroscopic analysis of Fe resolved into H 2 SO 4 solution. 75 Table 1-5. Results of measurement of optical density of irradiated Fricke dosimeter with different dosage and their uncertainties based on control solution. 79 Table 2-1. Impurity analysis for LiF:Mg,Cu,Na,Si TL detector. 88 Table 2-2. The relative TL intensities of the MCNS, MC, CNS and MNS samples. 95 Table 2-3. The TL parameters of each deconvoluted glow curve, determined by executing the CGCD method. 106 Table 2-4. Relative dose response function of KLT-300 TL detector. 110 Table 2-5. Relative energy response of KLT-300 TL detector. 112 Table 2-6. Reproducibility of KLT-300 TL detector. 114 Table 2-7. Student's distribution. 116 Table 3-1. Characteristics of ionization chambers used in radiotherapy dosimetry. 120 Table 3-2. Reference conditions of the ionization geometry for absorbed dose measurement using an ionization chamber in a phantom. 132 Table 3-3. Quadratic fit coefficients for pulsed radiation. 134 Table 3-4. Values for k m, k att and km katt for the ionization chambers. 136 Table 3-5. The stopping power ratio water to air at the reference depth. 138 Table 3-6. Valuef the the ractor k m (= s air,m ( en / ) m,air ). 140 Table 3-7. Correction factor p cel for a Farmer type of chamber. 140 Table 3-8. Primary standards in the comparisons of absorbed dose to water at the BIPM. 155 Table 3-9. Characteristics of cylindrical ionization chamber types. 163 Table 3-10. Reference conditions recommended for the calibration of ion chamber in Co-60 in standard laboratories. 167 Table 3-11. Quadratic fit coefficients for the calculation of k s. 171 Table 3-12. Reference conditions for the determination of absorbed dose to water in Co-60 gamma ray. 173 Table 3-13. Determination of the absorbed dose to water in a 60 Co ray beam. 174
Table 3-14. Reference conditions for the determination of photon beam quality (TPR 20,10 ). 179 Table 3-15. Reference conditions for the determination of absorbed dose to water in high energy photon beams. 179 Table 3-16. Calculated value of k Q for high energy photon beams for various cylindrical ion chambers as a function of beam quality TPR 20,10. 182 Table 3-17. Determination of the absorbed dose to water in a high energy photon beam. 184 Table 3-18. Values for the factors P dis, P wall and P cel and for the Product S w,air P Q in Co-60 gamma radiation for various cylindrical ionization chamber. 193 Table 3-19. Estimated relative standard uncertainties of the parameters entering into the denominator of Eq.(3-39) at the Co-60 beam quality. 194 Table 3-20. Estimated relative standard uncertainties of the calculated values for k Q for high energy photon beams. 196 Table 3-21. Comparison of some of the beam quality parameters. 201 Table 3-22. Water absorbed dose with the photon energies. 208 Table 3-23. Radiation field characteristics to be used in the energy response experiments of the TL pellets. 209 Table 3-24. Absorbed doses to water for the high energy photons used in this experiment. 211 Table 3-25. Relative energy responses to Co-60 for KLT-300 with the phantom types. 212 Table 3-26. Relative energy responses to Co-60 for several types of TLDs for a solid phantom. 212 Table 3-27. Hospitals and radiation sources to irradiate. 215 Table 3-28. Results for TLD Response : Reference value is KCCH. 216 Table 3-29. Results for TLD Response for the average of the all response values. 217 Table 3-30. Results for TLD Response : Physicist o/x. 218 Table 3-31. Results for TLD Response : Area. 219
List of Figures Fig. 1-1. Systematic diagram of evaluating dosage from High Energy / Dose Irradiation System using Chemical Dosimeter. 7 Fig. 1-2. Variation with energy of the ratio of the mass energy absorption coefficients of water and air. 9 Fig. 1-3. Illustrating transient CPE for high-energy indirectly ionizing radiation incident from the left on a slab of material. 10 Fig. 1-4. Wheatstone Bridge. Depending on the particular application, one or more of the bridge resistors through are thermistors. 17 Fig. 1-5. Schematic quasi-adiabatic calorimeter heating curves. 17 Fig. 1-6. Schematic Diagram of Heat-Compensated Graphite Calorimeter. 19 Fig. 1-7. Schematic view of the calorimeter gaps. 30 Fig. 1-8. Picture of Jacket Lid (a) and Base (b) Picture of shield lid and base. 32 Fig. 1-9. Picture of Core-Jacket-Shield Assembly after connecting thermistor wires and mounting supports for core and jacket. 33 Fig. 1-10. Blue print of graphite calorimeter. 35 Fig. 1-11. Picture of graphite calorimeter with Core-Jacket-Shield assembly. 36 Fig. 1-12. (a)wiring for Core Bridge Thermistor, (b) Wiring for Jacket Bridge Thermistor, (c) Wiring for Heater Leads. 39 Fig. 1-13. Photograph of Core-Jacket-Shield Assembly Inserted into Medium with connection of measurement wires. 40 Fig. 1-14. Schematic Diagram of Circuit for (a) Calibration run and (b) Measurement run. 41 Fig. 1-15. Photograph of homemade measurement and control box and Lock-in Amplifier. 43 Fig. 1-16. (a) Diagram of Thermistor (b) SEM Picture of Thermistor (c) Temperature behavior of sensor and heater thermistor in the range (d) Characteristics of sensor and heater thermistors. 45 Fig. 1-17 Schematic diagram of High Vacuum System connected to Calorimeter. 46 Fig. 1-18. Visual Basic Window showing that PC controls Lock-in Amplifier. 48 Fig. 1-19. Flow chart of computer interfacing with Lock-In Amplifier. 49 Fig. 1-20. Flow chart of Visual Basic Program communicating with Lock-in Amplifier. 50 Fig. 1-21. (a) Photograph of Calorimetric measurement and control system (b) Display of
heating and cooling curve on the graphic chart recorder for the calibration run using the equivalent circuit of core bridge. 51 Fig. 1-22. Photograph of Measurement system of thermal behavior of Core and Core+Jacket in vacuum as a function of time. 52 Fig. 1-23. (a) Theoretical Thermal behavior of Core, Jacket and Core+Jacket (b) Experimental Thermal behavior of Core and (c) Core+Jacket. 53 Fig. 1-24. (a) Picture of calorimeter connected with vacuum system inside radiation room (b) Picture of measurement system in the control room. 54 Fig. 1-25. Temporal Behavior of Bridge Output Voltage in Calibration Run and Measurement Run. 56 Fig. 1-26. Linac geometry for high energy X-ray measurement. 58 Fig. 1-27. Photograph of vial and container for the Fricke dosimeter. 66 Fig. 1-28. Photograph of reservoir preserving primary purified water and pipette cleaning system. 68 Fig. 1-29. Schematic diagram of sample holder for spectrophotometer Cary 4000. 70 Fig. 1-30. Photography of vial and cuvette for Fricke dosimeter. 72 Fig. 1-31. (a) Photography of vial and holder to stand vial in upright position. (b)photography of irradiation of 60 Co gamma-ray to Fricke Dosimeter. 77 Fig. 1-32. Photography of Spectrophotometer and measurement system. 79 Fig. 2-1. Schematic diagram of the sintering furnace; (a) cross-section, (b) top view. 83 Fig. 2-2. Dependence of main peak intensity of LiF:Mg,Cu,Na,Si on Mg concentrations. 84 Fig. 2-3. Dependence of main peak intensity of LiF:Mg,Cu,Na,Si on Cu concentrations. 85 Fig. 2-4. Dependence of main peak intensity of LiF:Mg,Cu,Na,Si on Na, Si concentrations. 86 Fig. 2-5. Dependence of the TL intensity of LiF:Mg,Cu,Na,Si on sintering temperature. 87 Fig. 2-6. The glow curves of powder-type and sintered pellet-type LiF:Mg,Cu,Na,Si TL materials. 89 Fig. 2-7. X-ray diffraction patterns of LiF:Mg,Cu,Na,Si. A) powder. B) sintered pellet. 90 Fig. 2-8. Schematic diagram of 3-D TL spectra measuring system. 92 Fig. 2-9. Schematic diagram of the spectrometer. 93 Fig. 2-10. Flow diagram of temperature control. 94 Fig. 2-11. The normalized TL glow curves for the samples: MCNS, MC, MNS and CNS. 95 Fig. 2-12. Isometric plot and contour plot of the TL spectra from the MCNS sample. 98
Fig. 2-13. Isometric plot and contour plot of the TL spectra from the CNS sample. 99 Fig. 2-14. Isometric plot and contour plot of the TL spectra from the MNS sample. 100 Fig. 2-15.Isometric plot and contour plot of the TL spectra from the MNS sample. 101 Fig. 2-16. Analysis of the spectra at each peak temperature of the TL glow curve of MCNS sample. 102 Fig. 2-17. Analysis of the spectra at each peak temperature of the TL glow curve of CNS sample. 102 Fig. 2-18. Analysis of the spectra at each peak temperature of the TL glow curve of MC sample. 103 Fig. 2-19. Analysis of the spectra at each peak temperature of the TL glow curve of MNS sample. 103 Fig. 2-20. Computerized glow curve deconvolution for the LiF:Mg,Cu,Na,Si TL detector. The scattered curve is measured data. 105 Fig. 2-21. The glow curves of KLT-300 and TLD-100. 107 Fig. 2-22 Dose response of KLT-300 TL detector as a function of absorbed dose. 109 Fig. 2-23 Relative dose response function of KLT-300 TL detector. 109 Fig. 2-24 Relative energy response of LiF:Mg,Cu,Na,Si TL detector. 112 Fig. 2-25 Reproducibility of KLT-300 TL detector. 115 Fig. 3-1. Electron energy spectra and their parameters. 122 Fig. 3-2. An electron beam absorbed dose distribution in a water phantom. 123 Fig. 3-3. The two experimental set-ups to determine the quality of photon beams. 125 Fig. 3-4. The calibration chain for electron and high energy photons from PSDL to SSDL to user. 128 Fig. 3-5. Displacement of the effective point of measurement P eff (depth Zp eff ) from the center P(depth Z p ) of an ionization chamber. 130 Fig. 3-6. The corrextion factor for recombination P s in continuous radiation. 134 Fig. 3-7. Reference water phantom for absorbed dose determination. 135 Fig. 3-8. The perturbation factor Pu as a function of the quality of photon beams for different chamber wall materials. 139 Fig. 3-9. The fraction of ionization due to electrons arising in the chamber wall as a function of wall thickness for the photon beam given by. 141 Fig. 3-10. The ratio of Co-60 calibration factor N D,w /N K to demonstrate chamber to chamber variation for a large number of cylindrical chambers. 153
Fig. 3-11. Results of comparison of standards of absorbed dose to water (a) and air kerma (b) at the BIPM in Co-60 beam. 156 Fig. 3-12. Mean values of k Q at various photon beams measured at NPL in the UK for secondary ion chamber NE 2561 ( ) and NE 2611 ( ). 160 Fig. 3-13. Experimental set-up for the determination of the beam quality Q (TPR 20,10 ). 178 Fig. 3-14. Sigmoidal fits of calculated values of k Q for various ion chambers commonly used for reference dosimetry, as a function of photon beam qualities, Q (TPR 20,10 ). 183 Fig. 3-15. The effective point of measurement of a cylindrical ion chamber. 188 Fig. 3-16. The ratio of absorbed dose to water in Co-60 determined with calibration factors in terms of absorbed dose to water, N D,w and with calibration factors in terms of air kerma, N K.. 189 Fig. 3-17. Schematic diagram of linac head. (a) 6 MV Siemens MX2 (b) 10 MV Varian Clinac 2100C. 199 Fig. 3-18. Calculated photon energy spectra. (a) The 6 MV beam from the Siemens MX2; (b) The 10 MV beam from the Varian Clinac 2100C. 200 Fig. 3-19. Comparison of the calculated and measured depth dose curves. 202 Fig. 3-20. Comparison of the calculated and measured cross profiles. 204 Fig. 3-21. Experimental set-up for energy reponses of the TLDs. 210 Fig. 3-22. Relative energy responses to Co-60 for several high energy photons with different types of phantoms (left side) including the low energy photon regions(by air kerma) for a comparison (right side). 213 Fig. 3-23. Results for TLD Response: (Reference value is KCCH). 216 Fig. 3-24. Results for TLD Response for the average of the all response values. 217
i xxvi xxvii xxviiii 1 3 5 1 / 5 1. / 5 2. 60 2 TLD 81 1. KLT-300(LiF:Mg,Cu,Na,Si) TL 81 2. XRD 87 3. KLT-300(LiF:Mg,Cu,Na,Si) TL 91 4. TL 104 5. 106 3 117 1. 117 2. 150 3. 197 220 1 220 2 221 223 225
1-1. Core. 26 1-2. G-value. 61 1-3. Millipore system. 68 1-4. H 2 SO 4 Fe. 75 1-5. 60 Co Fricke Dosimeter. 79 2-1. LiF:Mg,Cu,Na,Si. 88 2-2. MCNS, MC, CNS MNS TL. 95 2-3. CGCD TL. 106 2-4. KLT-300. 110 2-5. KLT-300. 112 2-6. KLT-300. 114 2-7. Student's. 116 3-1.. 120 3-2.. 132 3-3. V1/V2. 134 3-4. k m k att k m k att. 136 3-5. Stopping Power Ratio Water to Air(S w,air ). 138 3-6. k m (= s air,m ( en / ) m,air ). 140 3-7. Farmer type p cel. 140 3-8. BIPM. 155 3-9.. 163 3-10.. 167 3-11. V 1 /V 2 k s. 171 3-12. Co-60. 173 3-13. Co-60. 174 3-14. (TPR 20,10 ). 179 3-15.. 179 3-16. TPR 20,10 k Q. 182 3-17.. 184 3-18. P dis, P wall, P cel S w,air P Q. 193 3-19. Co-60 (3-39). 194
3-20. k Q. 196 3-21.. 201 3-22.. 208 3-23. TLD. 209 3-24.. 211 3-25. KLT-300 Co-60. 212 3-26. TLD Co-60. 212 3-27.. 215 3-28. TLD ( ). 216 3-29. TLD ( ). 217 3-30. TLD (Physicist / ( )). 218 3-31. TLD ( ( )). 219
1-1. /. 7 1-2.. 9 1-3.. 10 1-4. thermistor Wheatstone bridge. 17 1-5. heating curve. 17 1-6.. 19 1-7. gap. 30 1-8. 6 m Al mylar film (a) Jacket Lid Base, (b) Shield cap base. 32 1-9. Thermistor Core-Jacket-Shield Assembly. 33 1-10.. 35 1-11. Core-Jacket-Shield assembly. 36 1-12. (a) Core (b) Jacket thermistor (c) heating thermistor. 39 1-13. Medium Core-Jacket-Shield Assembly. 40 1-14. (a) (b). 41 1-15. Lock-In Amplifier. 43 1-16. (a) Thermistor (b) SEM thermistor (c) heating thermistor (d) heating thermistor. 45 1-17. 46 1-18. Visual Basic PC Lock-In Amplifier. 48 1-19. Lock-In Amplifier PC interfacing flow chart. 49 1-20. Lock-In Amplifier data flow chart. 50 1-21. (a) system (b) Graphic chart recorder core bridge heating cooling. 51 1-22. Core Core+Jacket system. 52
1-23. (a) Core, Jacket and Core+Jacket (b) Core, Jacket (c) Core+Jacket. 53 1-24. (a) system (b) system. 54 1-25. Bridge Output Voltage. 56 1-26. X-. 58 1-27. Fricke Dosimeter Vial Container. 66 1-28. 1 pippet cleaning system. 68 1-29. Cary 4000 Spectrophotometer sample holder. 70 1-30. Fricke Dosimeter Vial Cuvette. 72 1-31. (a) Vial holder (b) Fricke Dosimeter 60 Co. 77 1-32. Spectrometer system. 79 2-1. ; (a), (b). 83 2-2. Mg LiF:Mg,Cu,Na,Si. 84 2-3. Cu LiF:Mg,Cu,Na,Si. 85 2-4. Na Si LiF:Mg,Cu,Na,Si. 86 2-5. LiF:Mg,Cu,Na,Si TL. 87 2-6. LiF:Mg,Cu,Na,Si TL. 89 2-7. LiF:Mg,Cu,Na,Si XRD. A), B). 90 2-8. 3 TL. 92 2-9.. 93 2-10.. 94 2-11. MCNS, MC, MNS CNS.. 95 2-12. MCNS TL 3. 98 2-13. CNS TL 3. 99 2-14. MC TL 3. 100 2-15. MNS TL 3. 101 2-16. MCNS. 102 2-17. CNS. 102 2-18. MC. 103 2-19.. MNS. 103
2-20. LiF:Mg,Cu,Na,Si TL.. 105 2-21. KLT-300 TLD-100. 107 2-22 KLT-300. 109 2-23 KLT-300. 109 2-24 KLT-300. 112 2-25 KLT-300. 115 3-1. : (a) ; (0) ; (z) z. 122 3-2.. 123 3-3.. (a) - (SCD). (b) - (SSD). 125 3-4. PSDL, SSDL. 128 3-5. P( P z ) P eff. 130 3-6. Ps. 134 3-7.. 135 3-8. P u 139 3-9.. 141 3-10.. 153 3-11. Co-60 Ka. 156 3-12 NE 2561 k Q. 160 3-13.. 178 3-14. k Q. 183 3-15.. 188 3-16. Ka N D,w Co-60. 189 3-17. Linac head. 199 3-18.. 200 3-19.. 202 3-20.. 204 3-21.. 210 3-22.. 213 3-23. TLD ( ). 216 3-24. TLD ( ). 217
. ( 3 ). 50,.. / /. 1) /, 2) ( X- ) /. 1. / / X-
60 Co ( 0.96 %) 2. TLD TLD ( 5% ) TLD dosimetric 3 TL TLD dopants 3. / TLD ( 20 MeV )
1., TLD. (BIPM) 2 channel. (15 50 MeV). 1 (, ARPANSA, NMIS, PTB, BIPM ) / 10. IAEA. MD Anderson. 2. /. /
. (Heat-Loss-Compensated Calorimeter), FeSO 4 Fricke Dosimeter.. 3. 20 MeV 2 Gy/min. 1.25 MeV Co-60 / 50 %., dosimetric (NuTRM) 90 %.. -, 60 Co ( 70 %) 60 Co - ( 50%) ( 40 %)
1 / 1. /..,. ( 3 )., (TLD). Air kerma IAEA protocol.. (Chemical Dosimeter), (NIST, NPL, NRC ).
.,.. 1-1.. system 60 Co (1) ( ) (absorbed dose; ).,..
화학선량계의제작및보급 측정하고자하는고선량방사선발생장치로부터보급된화학선량계에방사선조사 흑연열량계를이용한감마선및 X-선흡수선량평가기술및적용기술개발 흑연과물의환산인자 치료선량방사선의조사에따른화학선량계용액의몰농도변화몰농도변화에의한 optical absorbance 변화량측정 흑연열량계제작기술을기반으로한물열량계제작및특성평가물열량계를이용한감마선및 X-선흡수선량평가기술및적용기술개발 감마선과 X-선에대한물의흡수선량값결정과기준선량으로활용 Optical absorbance 변화량으로부터조사된방사선의물에대한흡수선량결정기준흡수선량과비교하여치료용방사선발생장치의선량및불확도평가및통보 치료용방사선발생장치의선량평가및정도체계확립 1-1. /. (Systematic diagram of evaluating dosage from High Energy / Dose Irradiation System using Chemical Dosimeter.)
air kerma K air. Kair CPE CPE. air kerma K (energy fluence) - (mass-energy absorption coefficient) K air.. m, n Km Kn.,. 1-2.. ( ) (CPE: Charge-Particle Equilibrium) (1.1).
.,. (homogeneous). (uniform field). (, ).., 1-3. 1-2.. (Variation with energy of the ratio of the mass energy absorption coefficients of water and air.)
1-3.. (Illustrating transient CPE for high-energy indirectly ionizing radiation incident from the left on a slab of material.) (2) ( ) (absorption process),,, 2,,. (dissipation).. (Heat Transfer) (1.2)
(convection), (conduction) (radiation).,. gradient., thermal gradient. (1.3).. Heat flow equation thermal gradient., (thermal conductivity)..,, 4 Stefan-Boltzmann,. ( ),
.. (Temperature Measurement)...,., thermistor., thermistor (-50 500 ) 1-2% -4%. Thermistor thermistor, (material constant)., -. thermistor,,. Thermistor 1 mm glass bead thermistor. bead thermistor thermistor temperature gradient,.
(Wheatstone bridge) thermistor Wheatstone bridge. 1-4 Wheatstone bridge. bridge thermistor.. bridge (power coupling impeadance matching) (optimum signal to noise ratio) bridge. thermistor. (Resistance Sensitivity; ) thermistor thermistor. thermistor V/. (Temperature Sensitivity; ) thermistor. V/. (Nonlinearity; 100 ). (, )
( ) (1.2) (isothermal) (non-isothermal) (phase transition) (ice calorimeter). (Constant-temperature-environment calorimeter) (adiabatic calorimeter).,, (quasi-adiabatic calorimeter). (two-body) (three-body) core jacket core jacket thermal buffer shield (1.3).. (Isothermal calorimeter). 10-4. core jacket core.. (Constant-temperature-environment calorimeter) core jacket. (dissipation). core
(energy flow). core jacket. (Adiabatic calorimeter). jacket feedback core. core jacket. (20 rads/min.). (Constrained Quasi-Adiabatic calorimeter) thermal head (core jacket ) jacket. core, jacket shield, core jacket jacket shield shield. 1-5. initial rating period, final rating period. W. P White period. Initial rating period shield
. core jacket Newton (cooling law) shield drift. thermal head 0 core. period core jacket (dissipation). core jacket thermal head. period jacket shield. shield setting feedback. period final rating period (drift). thermal head final rating period period. thermal head 0 core jacket. thermal head core, jacket shield thermal head. - jacket..
1-4. thermistor Wheatstone bridge. (Wheatstone Bridge. Depending on the particular application, one or more of the bridge resistors through are thermistors.) T Core Jacket T Shield 1-5. heating curve. (Schematic quasi-adiabatic calorimeter heating curves.) (3) core, jacket, shield medium (Heat-Loss-Compensated Calorimeter) (1.4). core
. core jacket core thermal gradient.,,, thermal gradient (1.5). core., core jacket core jacket, core heater core core jacket jacket. jacket core jacket jacket core. Thermal gradient. (calibration run) (measurement run), core, jacket shield core core core jacket. core thermal gradient core. core heater heater thermal gradient thermal gradient. thermal gradient core heater (conducting film) core core
core jacket heater thermistor, Wheatstone bridge arm. 1-6. core jacket shield. thermistor core jacket heater. medium medium (thermo-regulated). shield shield jacket, shield (thermally floating). 1-6.. (Schematic Diagram of Heat-Compensated Graphite Calorimeter.) (4) ( ) core, jacket, shield medium.
Core Core 20 mm 3 mm. Core core core 0.5 mm thermistor Wheatstone bridge. Core 2 thermistor 1.5 k thermistor, 20 k thermistor calibration heater. Core 3 polystyrene. Jacket Jacket core Core 2 jacket base 3 polystyrene 1 mm 1 mm. Jacket lid base core. Jacket lid base 6 m coating mylar film core mylar film core core jacket. Jacket jacket lid base core core jacket. Jacket base core thermistor 5 cm core core jacket polystyrene. core pumping jacket. jacket jacket cap cap jacket base. Shield Jacket shield 3 1 mm polystyrene
shield core jacket. shield 36 mm, 74 mm core 85. Shield medium 2 mm (front surface) (fluctuation) core. Shield 1 mm cap. Shield mylar. Medium Medium core shield medium mylar. Medium Shield 2 mm medium (vacuum box). 15 cm 10 cm., medium medium thermoregulator. ( ) ( 99.97 %) core jacket (thermistor, polystyrene, aluminized mylar film, platinum wire, Cu wire, Epoxy ) heat capacity core jacket. heat capacity core jacket. core, jacket shield. core jacket heat capacity core jacket. Core Core thermistor and platinum, thermistors core
epoxy, graphite thermistor radiation resistant mylar film, polystyrene. core (effective mass). core. Core = (core ) (1+ ), :, : Core Core (99.973 % ) 1.4372 g. 0.06 % core 1.4381 g. Core core 2.493 mg. 1.06 g/cm 3 0.127 cm polystyrene 12 mm. 2 mm core core 1.25 mg. core 3 1.875 mg. core core core 50 %. core 1 mg. Core Thermistor Epoxy epoxy 0.2 mg. Epoxy
0.2 mg epoxy 2 mm. core 0.6 mg., Core thermistor 0.33 mm 4 mm thermistor epoxy 0.4 mg. Core core mylar strip Core thermistor graphite mylar strip thermistor mylar strip 0.8 mm 4 mm 0.064 cm 2 mylar strip 4 mm 1.75 mm 0.0125 mm. mylar strip 2.0 cm 4.7 cm 0.0125 mm mylar mylar strip. mylar 0.01764 g, mylar strip =0.131 mg., thermistor mylar strip 4 mm 1 mm 0.0125 mm. Mylar strip, mylar strip Epoxy Mylar strip 0.064 cm 2 epoxy 2.5 mg/cm 2. mylar strip epoxy 0.16 mg 0.2 mg. mylar strip 0.2 mg. Thermistor Thermistor 0.25 mm 2.6 g/cm 3 0.15 cal/g o C thermistor
. Platinum Thermistor lead 0.025 mm platinum platinum 21.4 g/cm 3 0.0324 cal/cal/g-oc., core 4 mm platinum lead thermistor 4 lead. Thermistor platinum lead 0.05 mm #44 2 mm mylar strip platinum lead core core core 2 mm. 8.9 g/cm 3 0.092 cal/g o C = 0.14 mg. core 1-1 0.00917 cal/ o C. core (1.4381 g) (1+0.00371) = 1.4434 g core 1.4434 g. Jacket jacket (lid base) core. Jacket base core thermistor., polystyrene jacket jacket
thermistor shield 5 cm. core jacket jacket lid jacket jacket core. core jacket aluminized mylar film jacket lid. core aluminized mylar film jacket. core jacket thermistor jacket core mylar film jacket. core jacket 1.43810 g (Core), 0.89791 g (Jacket lid), 0.62345 g (Jacket base) jacket (lid base) 1.52139 g. jacket core jacket. core. ATJ (300 K) 0.1721 cal/g o C core 1.43810 g 0.1721 cal/g o C = 0.2475 cal/ o C.
1-1. Core. (Heat Capacity of bare graphite and each impurity in Core.) Component Mass (mg) % of Core Specific Heat (cal/g o C) Heat Capacity (cal/ o C) Core (Graphite+Ash) 1438.1 100.000 Pure Graphite 1437.7 99.973 0.1721 0.24750 Ash 0.4 0.027 Ca 0.08 0.006 0.156 0.000012 K 0.08 0.006 0.180 0.000014 Fe 0.08 0.006 0.106 0.000008 Si 0.08 0.006 0.168 0.000013 V 0.08 0.006 0.116 0.000009 Core Support (polystyrene) 1.0 0.07 0.32 0.000320 Core Support 0.6 0.34 0.000204 Epoxy for Thermistor embedding Cementing mylar film to core Cementing leads to mylar strips 0.4 0.34 0.000136 0.2 0.34 0.000068 0.2 0.34 0.000068 Mylar strips 0.12 0.32 0.000038 Thermistor 0.04 0.15 0.000006 Platinum leads 0.25 0.032 0.000008 Copper leads 0.14 0.092 0.000013
Jacket base core jacket base. core jacket core jacket base. jacket base (0.3932) (0.2475 cal/ o C) = 0.0973 cal/ o C. jacket base. Jacket core aluminized mylar film jacket base mylar film 0.002907 g (jacket base ) epoxy 0.01009 g (jacket base ). jacket base (0.62345 g) (0.1721 cal/g o C)+(0.02907 g) (0.320 cal/g o C)+(0.01009 g)(0.340 cal/g o C) = 0.11166 cal/ o C 0.11166-0.0973 = 0.01436 cal/ o C. jacket base ATJ. jacket base 0.62345+0.002907+0.01009-0.0834 = 0.5530 g. Jacket lid jacket lid jacket jacket lid (0.6068) (0.2475 cal/ o C) = 0.15018 cal/ o C., jacket lid mylar film 0.002916 g (jacket lid ), 0.002121 g (jacket lid ) 0.005037 g, epoxy 0.02470 g. jacket lid (0.89791 g) (0.1721 cal/g o C) +(0.02470 g) (0.340 cal/g o C)+(0.005037 g) (0.32 cal/g o C) =
0.16454 cal/ o C 0.16454-0.15108 = 0.01436 cal/ o C 0.0834 g Jacket lid 0.89791 + 0.02470 + 0.005037-0.0834 = 0.84425 g. Jacket lid, jacket base, shield cap, shield base Medium 6 m aluminized mylar film mylar film emissivity. Stefan-Boltzmann emissivity (1.6).,, (effective emissivity)., emissivity, emissivity,. ( ) Gap Gap Correction (1.7) 60 Co (perturbation). core primary beam. core jacket lid core. scattered beam.
2 3 mm. Monte Carlo. (Determination of gap correction factor) (gap correction factor)., core.,, core kerma. core core. core (cross section) primary beam scattering. 1-7 gap.
1-7. gap : 1 (core ), 2 (jacket lid base ), 3 (jacket base shield ), 4 ( ). (Schematic view of the calorimeter gaps : gap 1 (around the core), gap 2 (between jacket lid and base), gap 3 (between jacket base and calorimeter body), gap 4 (between calorimeter and added graphite plate).) (5) core, jacket, shield medium 0.05 cm 0.0254 cm thermistor core jacket, jacket shield 5 mm polystyrene 120 core jacket, jacket shield shield medium 6 m aluminized mylar film jacket shield epoxy.
( ) drill core 0.5 mm, 2 mm 0.33 mm thermistor heating thermistor. Thermistor 3 micrometer thermistor. thermistor Digital Voltmeter thermistor 30 M., thermistor 0.025 mm, 8 mm - 2 cm 0.045 mm insulation strip core. Thermistor core jacket base jacket shield 1 mm jacket shield thermistor. ( ) Core 3.5 mm, 0.5 mm polystyrene. core 16 mm 120 o 0.5 mm core. ( ) Jacket lid, jacket base, shield cap, shield base medium 6 m aluminized mylar film film jacket lid, shield cap, medium cavity teflon mylar film working time epoxy. mylar film emissivity. Stefan-Boltzmann emissivity.,
,., emissivity, emissivity,. 6 m aluminized mylar film coating emissivity 0.044 core jacket effective emissivity. jacket lid base shield cap base 1-8. (a) (b) 1-8. 6 m Al mylar film (a) Jacket Lid Base, (b) Shield cap base. (Picture of Jacket Lid (a) and Base (b) Picture of shield lid and base. Both parts are coated by aluminized mylar film of 6 m.) ( ) Jacket thermistor base core thermistor jacket shield. shield 5 cm. jacket lid jacket jacket core. core jacket aluminized mylar film jacket lid.
( ) Jacket base 9 mm, 1.0 mm polystyrene. jacket 20 mm 120 shield 7.5 mm shield jacket lid shield gap 0.5 mm. 1-9 core jacket thermistor core jacket core-jacket-shield assembly. 1-9. Thermistor Core-Jacket-Shield Assembly. (Picture of Core-Jacket-Shield Assembly after connecting thermistor wires and mounting supports for core and jacket.) ( ) Core jacket lid gap theory 0.5 mm. ( ) Shield base core jacket thermistor 120 0.15 cm shield base 2.5 cm, 0.45 cm lucite shield base 20. Shield thermistor shield base shield heater base
., shield heater ( : 120.01 g, : ) thermistor 3 k, 1/2 Watt carbon resistor 4 mm, 16 mm conductive epoxy. ( ) Shield lid base 6 mm 120 5 mm. shield align shield medium 1 mm. ( ) Medium 13 cm core-jacket-shield assembly 125 cm 2 graphite block medium 5 cm. Medium core-jacket-shield assembly 120 1.75 mm., heater shield thermo-regulator 303 K. heater medium. ( ) Medium fluctuation 152.4 mm, 0.127 mm mylar film., pumping mylar film film. ( ) Medium shield aluminized mylar film shield., medium.
( ) Medium (Vacuum Housing) Lucite Perspex (polymethyl methacrylate) medium medium mylar film 14.5 cm, 0.5 cm. core-jacket-shield assembly head case lucite. ( ) head core, jacket shield thermistor 18 lucite rod BNC connector 32 16 Amphenol connector. pumping system pumping port ground port medium heater thermo-regulator port. 1-10 3-1-11 Core-Jacket-Shield assembly. 1-10.. (Blue print of graphite calorimeter.)
1-11. Core-Jacket-Shield assembly. (Picture of graphite calorimeter with Core-Jacket-Shield assembly.) (6) Core, Jacket, Shield Core, Jacket, Shield 0.045 mm. Thermistor platinum 0.025 mm 0.045 mm Shield lucite ring. ( ) Wheatstone Brige Core thermistor Core thermistor platinum 0.025 mm 1 cm 0.045 mm 4.5 cm core jacket shield. 4.5 cm jacket shield shield lucite ring 7 cm. 3.8. Lucite ring terminal board 10
60cm #36 120 cm 0.0136 /cm = 1.62. 1-12 (a). ( ) Wheatstone Brigde Jacket thermistor Jacket thermistor core 0.045 mm. Jacket thermistor 4.5 cm core jacket jacket base shield 4.5 cm 7 cm shield lucite ring. 3.8. terminal board 60 cm #36. 1-12 (b). ( ) Core Jacket Heater Core Jacket Heater 0.045 mm. Heater thermistor platinum 0.025 mm 1 cm 0.045 mm 6.1 cm jacket shield. 4.5 cm jacket shield shield lucite ring 8.2 cm heater lucite ring 4.23. Heater 1-12 (c). ( ) Core Jacket Core Jacket 0.015 mm Moleculoy. Moleculoy 75 20 #44 320. Moleculoy 49 cm 3541.7. Core
Jacket. Core 10.55 cm = 1.25 cm (core jacket base ) + 1.5 cm (Jacket base shield ) + 8.3 cm (Shield hole lucite ring ) Jacket 8.6 cm = 1.5 cm (Jacket base shield ) + 7.1 cm (Shield hole ring ) Shield ring, core, jacket, shield thermistor #36 Lucite rod 2 BNC connector 32 16 Amphenol connector. core-jacket-shield assembly 1-13.
Core Jacket Shield Lucite Terminal Thermistor Ring Board (Vaccuum) 4.5 cm of 0.045 mm Cu wire 7.0 cm 0.045 mm dia. wire 60 cm length of #36 Cu wire Total Resistance: 1.01 Total Resistance: 1.58 Total Resistance: 1.62 4.5 cm, 0.045 mm dia. Cu wire, Total resistance: 1.01 (a) Jacket Shield Lucite Terminal Thermistor Ring Board (Vacuum) 4.5 cm, 0.045 mm dia. Cu wire 7.0 cm 0.045mm dia. Cu wire 60 cm length, #36 Cu wire Resistance: 1.01 Resistance: 1.60 Resistance: 1.62 (b) Core Jacket Shield Lucite Terminal Thermistor Ring Board (Vaccuum) 6.1 cm, 0.045 mm dia. Cu wire 8.2 cm, 0.045 mm Cu wire 60 cm length #36 Cu wire Resistance of wire: 1.37 Resistance: 1.85 Resistance: 1.62 4.5 cm, 0.045 mm Cu wire, Resistance: 1.01 (c) 1-12. (a) Core (b) Jacket thermistor (c) heating thermistor. ((a)wiring for Core Bridge Thermistor, (b) Wiring for Jacket Bridge Thermistor, (c) Wiring for Heater Leads.)
1-13. Medium Core-Jacket-Shield Assembly. (Photograph of Core-Jacket-Shield Assembly Inserted into Medium with connection of measurement wires.) (7) (Measurement and Control Circuit System) ( ). thermistor Wheatstone bridge arm bridge ( ) bridge thermistor bridge differential output voltage. (1.6) core, jacket shield medium thermistor arm equal-arm Wheatstone bridge core jacket thermistor arm 5. Bridge thermistor bridge differential output voltage Lock-in Amplifier signal GPIB interfacing PC data acquisition monitor output voltage graphic mode
. graph data. 1-14. (a) (b) 1-14. (a) (b). (Schematic Diagram of Circuit for (a) Calibration run and (b) Measurement run.) ( ) (Measurement and Control Box). thermistor Wheatstone bridge arm bridge ( ) bridge thermistor bridge differential output voltage. core, jacket shield medium thermistor arm equal-arm Wheatstone bridge core jacket thermistor arm 5. Bridge thermistor bridge differential output voltage Lock-in Amplifier signal
GPIB interfacing PC data acquisition monitor output voltage graphic mode. graph data. bridge (preliminary procedure), (calibration run) (measurement run). bridge C+J mode, C mode, J mode, S mode M mode mode.. C+J mode core thermistor jacket thermistor bridge arm arm,., core jacket thermistor core jacket arm. Bridge C mode bridge 0. J mode S mode. M mode mode bridge. mk, bridge. core heater core. core jacket core., core,. bridge arm 5 Helipot 0.5, 5 5 mode 10 Helipot ( mode coarse control fine control
Helipot ) Wheatstone birdeg arm thermistor.. calibration heating., 0.1 10 k, decade box contact resistance 1.7 k shunt. 1-15.. 1-15. Lock-In Amplifier. (Photograph of homemade measurement and control box and Lock-in Amplifier.) ( ) Heater thermistor thermistor 1.5 k, heating 20 k small bead thermistor MOS (metalic oxide semiconductor) -. coating response time power sensitivity. Thermistor 0.0254 cm - 25 m, 0.8 cm. thermistor
(dissipation constant), thermistor self-heating., thermistor 63.2 % thermal time constant 0.5 sec. heating thermistor Scanning Electron Microscope thermistor thermistor (1.8) 1-16.
(a) (b) Resistance of Sensor Thermisotr as a function of T Resistance of Heater Thermistor as a Function of T 60 1200 50 1000 Resistance (kω) 40 30 20 10 Resistance (kω) 800 600 400 200 0 0 200 220 240 260 280 300 320 340 360 380 400 Temparature (K) 200 250 300 350 400 450 Temperature (K) (c) (d). 1-16. (a) Thermistor (b) SEM thermistor (c) heating thermistor (d) heating thermistor. ((a) Diagram of Thermistor (b) SEM Picture of Thermistor (c) Temperature behavior of sensor and heater thermistor in the range (d) Characteristics of sensor and heater thermistors.)
( ) core core jacket shield. emissivity core. jacket shield 6 m aluminized mylar film Turbo molecular pump 10-5 torr. 1-17. 1-17.. (Schematic diagram of High Vacuum System connected to Calorimeter.) ( ) Data Aquisition Core, core bridge differential
output voltage V out. strip chart graph V out core V out V diff strip chart recorder V out data Lock-In Amplifier PC data graph graph core bridge output V diff least square fit core. Visual Basic. PC Lock-In Amplifier Lock-In Amplifier EG&G Model 5200 PC RS-232 serial port IEEE 488.2 GPIB port. RS-232 port data acquisition GPIB port., notebook PC GPIB board PCMCIA driver GPIB Measurement and Automation Lock-In Amplifier GPIB address PC. 1-18 PC Lock-In Amplifier 1-19 flow chart.
1-18. Visual Basic PC Lock-In Amplifier. (Visual Basic Window showing that PC controls Lock-in Amplifier.) core bridge output V out. (least square fit) V out V diff = (V out ) -(V out ). flow chart 1-20.
START NI-GPIB Interface Card Device Initialize Lock-In Amp Receive Serial Polling Data Initilize S earch for N I-G P IB D evice 0 (M aster ID ) NI-GPIB Device 0 Listener Mode Measurement Data Recording Scan GPIB Connect Device LOCK-IN AMP Model 5210 Instrum ent Address 12 Select Device LOCK-IN AMP Active Mode Set LOCK-IN AMP Communication Mode : Serial Polling Set LOCK-IN AMP Control Mode Close GPIB Device Disconnect & NI-GPIB Interface Terminate Control Command & ASCII CODE 13 Setting for Control LOCK-IN AMP Control Command Transfer Completed Program Exit? END Yes No LOCK-IN AMP RESTART Polling OK? No Yes Serial Polling Data & Receive Data CR Terminate code No Polling Completed Lock-In Amp Ok Control Command Correction Value Set & Display Data 1-19. Lock-In Amplifier PC interfacing flow chart. (Flow chart of computer interfacing with Lock-In Amplifier.)
Yes No Yes No No Yes 1-20. Lock-In Amplifier data flow chart. (Flow chart of Visual Basic Program communicating with Lock-in Amplifier.)
( ) mode core core heater core strip chart recorder (PC) thermistor thermistor core. core thermistor arm bridge thermistor heater thermistor. 1-21. thermistor 3 mw 100 core thermistor thermistor heating cooling process. (a) (b) 1-21. (a) system (b) Graphic chart recorder core bridge heating cooling. ((a) Photograph of Calorimetric measurement and control system (b) Display of heating and cooling curve on the graphic chart recorder for the calibration run using the equivalent circuit of core bridge.)
core jacket 1-22 core heating thermistor core jacket strip chart recorder. core jacket assembly core jacket core jacket emissivity aluminized mylar film. core core core jacket cap aluminized mylar film jacket core + jacket 1-22. Core Core+Jacket system. (Photograph of Measurement system of thermal behavior of Core and Core+Jacket in vacuum as a function of time.) core jacket core jacket core jacket
. core + jacket + shield assembly graphite medium core jacket. core core jacket 1-23. (a) (b) (c) 1-23. (a) Core, Jacket and Core+Jacket (b) Core, Jacket (c) Core+Jacket. ((a) Theoretical Thermal behavior of Core, Jacket and Core+Jacket (b) Experimental Thermal behavior of Core and (c) Core+Jacket.) ( ) system bridge output voltage. 1-24 (a) (b).
, Lock-In Amplifier, notebook., Belden Cable. (a) (b) 1-24. (a) system (b) system. ((a) Picture of calorimeter connected with vacuum system inside radiation room (b) Picture of measurement system in the control room.) calibration 60 Co constant voltage source 20 W core. 1-25 (a) core bridge (A B ) V out 0.1 V heating (B E ) graph scale core bridge arm offset graph minimum scale. (E F ) core bridge V out V out V diff (D). V diff core.
bridge. bridge bridge core V diff. core bridge core. core V diff, core. core E C ( heating ) output voltage difference V diff, (core balancing resistance) R M (1.9) a, b, c. core core., 60 Co core 1-25 (b). 60 Co (B E ) core D R. M eff core M eff = (core ) (1+ )., core.
(a) (b) 1-25. Bridge Output Voltage. (Temporal Behavior of Bridge Output Voltage in Calibration Run and Measurement Run.) 60 Co 1 m, phantom (core ) core (1.10) P core : gap : : phantom : 60 Co : 60 Co. core, core Co-60 2.051 mgy/sec, 0.48 %.. X- (Co-60, X- ). Co-60
(BIPM) Co-60 ( 5.2 ) X-. X- (LINAC). Co-60.. ( ) X- (Collimator) X-., target X- 4 20 MeV bremsstrahlung X-. collimation X- collimation. beam flattening filter collimator filter X- collimation collimation X- monitor chamber additional filter X- X-. filter, monitor X- additional filtration. X- 1-26. ( ) (beam quality) Specifier
X- (energy width). detector beam quality specifier ( ). beam quality specifier 1-26. X-. (Linac geometry for high energy X-ray measurement.).. beam quality specifier. MV X- beam quality (tissue phantom ratio)
( 20 cm 10 cm ).. phantom ( ) (MV) (Dose conversion in megavoltage photon beam). (photon fluence) scaling theorem. theorem ( ).,,,,,, -, collision kerma.., Compton (pair production, bremsstrahlung, annihilation radiation ). ( ) X-
Co-60 2 MeV. collimator X-., Wheatstone Bridge thermistor.. 60 Co irradiator monitoring. X- Co-60. Co-60 X- (substitution method). 2.. (1.11) (aqueous dosimeter) (dilute solution) 10-10. H OH (free radical) H 2 H 2 O 2. 10-6
. (LET : linear energy transfer),. (dense track) reaction (back reaction: ) yield. X- LET yield yield yield LET. LET yield yield LET yield yield. yield G-value X radiation chemical yield, G(X). G-value 100 ev ( )., G(X) moles/j G(X) = G-value 1.037 10-7. 1-2 0.8 N H 2 SO 4 FeSO 4 yield. G(e - ag) G-value. 1-2. G-value. (Radiation chemical yield of free radicals and molecules for several radiations.). (dilute aqueous solution) dosimeter Fricke dosimeter, Dye tpye dosimeter, Benzoic Acid Fluorescence
Dosimeter, FeSO 4 Fricke dosimeter (1.12) (1) (2) (3) 20 30 MeV X- 60 Co 0.2 ev/nm (low LET) G-value (4) (5) 60 Co 0.1 % dosimeter. Fricke dosimeter.. Fricke Dosimeter Fricke dosimeter 40 Gy 400 Gy. Fricke dosimeter 0.8 N H 2 SO 4 FeSO 4 FeSO 4 X-. (1) (1.11) FeSO 4 Ferrous (Fe 2+ ) Ferric (Fe 3+ )., PH 1.0.. Fe 2+ + OH - Fe 3+ + OH - H + O 2 HO 2 Fe 2+ + HO 2 Fe 3+ + HO 2 HO 2 - + H+ H 2 O 2 Fe 2+ + H 2 O 2 Fe 3+ + OH + OH -
, HO 2 radical radical Fe 2+ Fe 3+, OH radical Fe 2+ H 2 O 2 2 Fe 2+. radiation chemical yield G(Fe 3+ ). G(Fe 3+ ) = 2 G(H 2 O 2 ) + 3 G(H) + G(OH) 1-2 G(Fe 3+ ) = 15.6 yield. 0.001 M FeSO 4 (half-life) 14 Fricke dosimeter (aftereffect). (2) Fricke Dosimeter Fricke dosimeter 3 0.001 M FeSO 4 Fe(NH 4 ) 2 (SO 4 ) 2 0.8 N H 2 SO 4. M 1000 cm 3 (molecular weight), N normality. NaCl NaCl dosimeter. Fricke dosimeter Fricke dosimeter 0.001 M NaCl. 0.001 M NaCl radiation chemical yield rate ( 10 Gy/ s ) NaCl ferric(fe 3+ ) NaCl. i), ii) NaCl G(Fe 3+ ) ( )., FeSO 4 [Fe 2 (SO 4 ) 3 ]. batch background
. (3) (Stability) FeSO 4 [Fe 2 (SO 4 ) 3 ] Fe 2+., 0.01 M FeSO 4 25 2 10-6 M/day..,. batch background.,. (4) Fricke dosimeter Fe 3+ CeSO 4 (titration) 40 Gy 500 Gy. (absorption spectroscopy) Fe 3+ FeSO 4 spectrophotometer dosimeter Fe 3+. 304 nm Fe 2+ (optical absorption coefficient) Fe 3+ 0.05 %. Fe 3+ molar extinction coefficient, 0.69 % /, 25 0.8 N H 2 SO 4 (Fe 3+ ) = 2197 liter/mole cm. 224 nm Fe 3+ peak 304 nm sensitivity
. (Fe 3+ ) 4565 liter/mole cm 304 nm 2187 20 30 0.13 % Fe 2+. molar extinction coefficient information (1.11)., = 6.02 10 23 molecules/mole (avogadro's number) = (control solution) = Fe 3+ Fe 2+ molar extinction coefficient ( 3040, 25 = 2197, = 1 liter/mole cm) = Fricke (0.8 N H 2 SO 4 1.024 kg/liter) = 6.24 10 13 ev/rad = (optical pathlength) G(Fe 3+ ) = Fe 3+ radiation chemical yield., 0.8 N H 2 SO 4 1 cm absorption cell 3040 25.. Fricke Dosimeter (Design Criteria) Fricke (Vial) pancake quartz 30 mm, 7 mm 1 mm. teflon Lucite stand spectrophotometer., vial 6 cm 8 cm 2 cm 6 cm 8
cm 3 mm polystyrene., (AAPM: American Association of Physicist in Medicine) protocol. Vial 1-27. 1-27. Fricke Dosimeter Vial Container. (Photograph of vial and container for the Fricke dosimeter.). (Fricke Dosimeter) System Fricke Dosimeter FeSO 4 Fe 2+ (ferrous) Fe 3+ (ferric). Ferrous Ammonium Sulfate hexahydrate [(NH 4 ) 2 Fe(SO 4 ) 2 6 H 2 O] (99.97 %), Sodium Chloride [NaCl] (100 %) Sulfruric Acid [H 2 SO 4 ] (95.5 %), Sulfruric Acid [H 2 SO 4 ] (51 %)., Millipore. RIOS 5 system MILLI-Q Gradient system
RIOS 5 system (Reverse Osmosis) 1 90 % 1 1 (monovalent), (polyvalent), 5. 1 30 L reservoir 1 MILLI-Q Gradient system Fricke 3. MILLI-Q Gradient system (activated carbon) nuclear (ion exchange resin)., UV lamp polisher cartridge,. 3 1-3. Fricke flask quartz water system (30 L) pipette acid cleaning system. 1-28 1 reservoir pipette cleaning. Spectrometer 224 nm 303 nm (optical absorbance). Hood.
1-3. Millipore system. (Characteristics of purified water produced by millipore purification system.) 1-28. 1 pipette cleaning system. (Photograph of reservoir preserving primary purified water and pipette cleaning system.)
. Spectrometer Sample Holder Spectrophotometer IAEA Dr. Ken Shortt, NIST Mr. Chris Soares Varian Cary 400 UV-VIS spectrophotometer. Cary 400 (1.13). floating" casting isolate Littrow (monochromator) out of plane (photometric noise) PbS detector 0., nitrogen purging. window back reflection. Cary 400 6 reference beam attenuator 7.00000,. 175 nm 900 nm Fricket 200 350 nm., G-value molar extinction coefficient spectrometer optical absorbance Temperature Control Unit. Unit sample holder Peltier cooling device Peltier water reservoir., sample holder sample holder. Cary 4000 UV-Scan (step size) 1 mm align
.. Spectrophotometer reference side dummy holder double measurement holder optical density., Sample holder 1-29. 1-29. Cary 4000 Spectrophotometer sample holder. (Schematic diagram of sample holder for spectrophotometer Cary 4000.). (1) Fricke dosimeter system Fricke dosimeter. ( ) Vial : 19 mm 8.5 mm 3 mm 10 mm pancake vial PTFE. Teflon vial. ( ) Cuvette : Spectrophotometer cuvette( 10 mm, 20 mm, 40 mm) control( ) vial spectrophotometer sample stand
. 1-30 vial cuvette. ( ) : Fricke dosimeter. - Ferrous Ammonium Sulfate hexahydrate [(NH 4 ) 2 Fe(SO 4 ) 2 6 H 2 O] (99.97 %) - Sodium Chloride [NaCl] (100 %) - Sulfruric Acid [H 2 SO 4 ] (95.5 %) - Sulfruric Acid [H 2 SO 4 ] (51 %) : ( ) 2 liter quartz flask : quartz. ( ) Bernoulli suction pump : flask beaker water suction pump. ( ) :. Mettler 220.00000 g( : 10 g) 1210.000 g ( : 1 mg). ( ) : Millipore. RIOS 5 system MILLI-Q Gradient system RIOS 5 system (Reverse Osmosis) 1 90 % 1 1 (monovalent), (polyvalent),. 1 MILLI-Q Gradient system Fricke 3. MILLI-Q Gradient system (activated carbon)
nuclear (ion exchange resin)., UV lamp polisher cartridge,. ( ) : Laminar Flow. ( ) pipette cleaning system : pipette. ( ), beaker, spatula, bottle, tweezer, funnel 1-30. Fricke Dosimeter Vial Cuvette. (Photography of vial and cuvette for Fricke dosimeter.) (2) Fricke Dosimeter Fricke radiation chemical yield Fricke,, vial cuvette.
-. (Fe) Fricke vial Fricke H 2 SO 4 5. Vial. ( ) 6N NaOH Vial ( grease). NaOH NaOH 12g 100 ml 50 ml. ( ) HCl HNO 3 3 1 HCl 36ml HNO 3 12 ml.. ( ) - ). Na 2 Cr 2 O 7 2 g 50ml (Cr ( ) Vial NaOH 10. ( ) Vial -. ( ) Vial 3 4. ( ) ( ). ( ).
( ) 0.4 M H 2 SO 4 vial., H 2 SO 4 (blank) Teflon bottle. vial 25 ppb(ppb : 10 1). 1-4. (3) Fricke Fricke FeSO 4 NaCl Al foil desiccator. H 2 SO 4 teflon bottle. Fricke. ( ) 2 L quartz flask 5 Millipore water purification 3 3/4 (1500 g). ( ) 95 % H 2 SO 4 beaker. Beaker 5 H 2 SO 4. ( ) 10 Gy. ( ) 0.784 g FeSO 4. ( ) 0.1169 g
NaCl. Fricke (concentration). ( ) Millipore 3 2043.4 g Fricke. ( ) Fricke (stopper) (air-saturated). ( ) dosimeter ( ). dosimeter. FeSO 4 : 1.00 10-3 mol / L H 2 SO 4 : 4.0 10-1 mol / L NaCl : 1.00 10-3 mol / L FeSO 4 NaCl Mettler. 0.05 %. 1-4. H 2 SO 4 Fe. (Result of mass spectroscopic analysis of Fe resolved into H 2 SO 4 solution.) (Fe) Signal (arbitrary unit) (Fe : 10 ppb) 1400 Teflon bottle 0.4 M H 2 SO 4 20 Vial 0.4 M H 2 SO 4 3500 - Vial 0.4 M H 2 SO 4 3500 (4) Vial Fricke Fricke vial vial
3 vial. Vial Fricke vial 5 3 rinse FeSO 4 rinse. 3 5 rinse FeSO 4 vial ultrasonic cleaner. vial. Vial FeSO 4 laminar flow. vial FeSO 4 3-4. vial Fe 3+. vial vial.. FeSO 4 vial vial beam vial holder alignment vial. vial holder 1-31-(a). (5) vial holder 60 Co 0.12 %. 0.03 %. vial. vial 15 30. Vial 10 40 Gy vial
. 3 vial 25 Gy, 30 Gy, 40 Gy 60 Co. Vial. 1-31-(b). (6) Cuvette Fricke Spectrophotometer Fricke vial cuvette cuvette sample holder vial cuvette 1 cm, 2 cm, 4 cm cuvette. Cuvette vial., 5 3 rinse cuvette cuvette. (a) (b) 1-31. (a) Vial holder. (b) Fricke Dosimeter 60 Co. ((a) Photography of vial and holder to stand vial in upright position. (b)photography of irradiation of 60 Co gamma-ray to Fricke Dosimeter.)
(7) (Absorbance) Varian Cary 400 UV-Vis. spectrometer Fricke cuvette (optical density). Fricke control ( Fricke ) spectrophotometer dual beam. Dual beam control sample holder cuvette single beam. control cuvette. cuvette control. 3020, 3030, 3040 2240 25. Fricke 2240 3040 10. control (OD) 1-5, spectrophotometer 1-32.. Fricke dosimeter spectrophotometer 3040, 2240. 3040 40 Gy Fricke dosimeter (OD) 0.141 (OD) 0.14. 3040, 2240 25. molar extinction coefficient
ICRU Report 35 (1.14) Fricke =1.004. 40 Gy 39.3 Gy. 1-5. Co Fricke Dosimeter. (Results of measurement of optical density of irradiated Fricke dosimeter with different dosage and their uncertainties based on control solution.) 1-32. Spectrometer system. (Photography of Spectrophotometer and measurement system.)
., molar extinction coefficient, = 6.02 10 23 molecules/mole (avogadro's number) = (control solution) = Fe 3+ Fe 2+ molar extinction coefficient = Fricke (0.8 N H 2 SO 4 1.024 kg/liter) = 6.24 10 13 ev/rad, = (optical pathlength) G(Fe 3+ ) = Fe 3+ radiation chemical yield., 0.8 N H 2 SO 4 1 cm absorption cell 3040 25 = = 38.88 Gy ( 3040 25 = 2197, = 1 liter/mole cm) = = 39.42 Gy ( 2240 25 = 4565, = 20 liter/mole cm) =1.004. = 39.04 Gy ( 3040 25 ) = 39.58 Gy ( 2240 25 )
2 TLD 1. KLT-300(LiF:Mg,Cu,Na,Si) TL. KLT-300 TL LiF,,,,, TLD. LiF TL.. (activator)., 100 300 (grain size).. LiF LiF 30. TL (2.1).. (atmosphere). LiF:Mg,Cu,Na,Si TL, TL Mg 0.00 mol% 0.25 mol%, Cu 0.00 mol% 0.07 mol% Na Si 0.00 mol% 1.50 mol%. TL
785 832. LiF:Mg,Cu,Na,Si TL. LiF, Mg MgSO 4 7H 2 O, Cu CuSO 4 5H 2 O, Na Si Na 2 O 2SiO 2 9H 2 O. ±10-6 g,. 150 (hot plate) LiF 30, -20. (grain size) 40 200. HCl. 4.5 mm 4.5 mm, 0.8 mm (pellet),. (chamber),. 2-1. -20, 250 (annealing) (pellet type) LiF:Mg,Cu,Na,Si TL.
(a) (b) 2-1. ; (a), (b). (Schematic diagram of the sintering furnace; (a) cross-section, (b) top view.). TL. 2-2 LiF:Mg,Cu,Na,Si TL Mg. Mg 0.00, 0.05, 0.10, 0.15, 0.20 0.25 mol%, Cu Na Si 0.05 mol%, 0.9 mol%. Mg TL 0.20 mol%. Mg. 0.20 mol%. Mg. LiF:Mg,Cu,Na,Si TL Mg LiF:Mg,Cu,P P. Bilski (2.2) W. Shoushan (2.3) Mg 0.2 mol%.
Intensity of Main Peak(arb. unit) 10000 8000 6000 4000 2000 Cu : 0.05 mol% NaSi : 0.9 mol% 0 0 0.05 0.10 0.15 0.20 0.25 Mg (mol%) 2-2. Mg LiF:Mg,Cu,Na,Si. (Dependence of main peak intensity of LiF:Mg,Cu,Na,Si on Mg concentrations.) Cu, Mg 0.20 mol%, Na Si 0.9 mol%, Cu 0.00, 0.01, 0.03, 0.05 0.07 mol%. 2-3 Cu. Cu. Cu 0.05 mol%. Cu LiF:Mg,Cu,Na,Si TL (2.4), LiF:Mg,Cu,P Cu. Cu Y. Nam 0.8 mol% (2.4). LiF:Mg,Cu,P TL Cu P. Bilski (2.2) 0.02 0.05 mol%. W. Shoushan (2.3) 0.00196 mol%.
Intensity of Main Peak(arb. unit) 10000 8000 6000 4000 2000 Mg : 0.20 mol% NaSi : 0.9 mol% 0 0 0.01 0.03 0.05 0.07 Cu (mol%) 2-3. Cu LiF:Mg,Cu,Na,Si. (Dependence of main peak intensity of LiF:Mg,Cu,Na,Si on Cu concentrations.) Na Si, Mg 0.2 mol%, Cu 0.05 mol% Na Si 0.0, 0.3, 0.6, 0.9, 1.2 1.5 mol%. 2-4 Na Si. Na Si. TL Na Si 1/3. Na Si. TL 0.9 mol%. TL Na Si, Y. Nam 1.8 mol% (2.4).
Intensity of Main Peak(arb. unit) 10000 8000 6000 4000 2000 Mg : 0.20 mol% NaSi : 0.9 mol% 0 0 0.3 0.6 0.9 1.2 1.5 Si (mol%) 2-4. Na Si LiF:Mg,Cu,Na,Si. (Dependence of main peak intensity of LiF:Mg,Cu,Na,Si on Na, Si concentrations.). TL TLD,., TL. 785, 800, 815, 825, 827, 830 832. 2-5. TL, 785 815. 815 TL 830. 832,. 832, TL., LiF:Mg,Cu,Na,Si
TL TL,,. 24 22 Total Signal (arb. unit) 20 18 16 14 12 10 8 780 790 800 810 820 830 840 Sintering Temperature( o C) 2-5. LiF:Mg,Cu,Na,Si TL. (Dependence of the TL intensity of LiF:Mg,Cu,Na,Si on sintering temperature.) 2. XRD. KLT-300 LiF:Mg,Cu,Na,Si TL,. HCl. LiF:Mg,Cu,Na,Si TL. LiF:Mg,Cu,Na,Si Mg, Cu Na ICP (inductively coupled plasma), Si EDS (energy dispersive spectroscopy). ICP JY50P (Jobin Yvon, France)
EDS INKA ENERGY (Oxford, UK). 2-1., Mg, Na 83 %, Si 67 %, Cu 0.05 mol% 0.0030 mol% 94 %., Cu HCl. Cu. LiF:Mg,Cu,P TL Cu, W. Shoushan (2.3) 0.00196 mol%, P. Bilski (2.2) 0.02-0.05 mol%. LiF:Mg,Cu,Na,Si Cu LiF LiF:Mg,Cu,P W. Shoushan. W. Shoushan, P. Bilski 1050 1000 30, LiF:Mg,Cu,Na,Si TL TL. 2-1. LiF:Mg,Cu,Na,Si. (Impurity analysis for LiF:Mg,Cu,Na,Si TL detector.) Element Method Initially doped concentrations of dopants (mol%) Finally remaining concentrations of dopants (mol%) Mg ICP 0.2 0.1611 Cu ICP 0.05 0.0030 Na ICP 1.8 0.2916 Si EDS 1.8 0.5819. KLT-300 XRD
LiF:Mg,Cu,Na,Si TL TL 2-1. (full width at half maximum). XRD(x-ray diffraction pattern). 2-6 x-. SIEMENS D5000(Germany). x- CaCO 3 TL. XRD Li 2 Si 2 O 5 (phase) SiO 2. LiF Na 2 O 2SiO 2 Li 2 Si 2 O 5,. SiO 2. XRD Li 2 Si 2 O 5. XRD,. TL Intensity(arb. unit) 8x10 6 7x10 6 6x10 6 5x10 6 4x10 6 3x10 6 sintered pellet powder 2x10 6 1x10 6 0 0 50 100 150 200 Channel number 2-6. LiF:Mg,Cu,Na,Si TL. (The glow curves of powder-type and sintered pellet-type LiF:Mg,Cu,Na,Si TL materials.)
4000 3500 A) Li2Si2O 5 LiF LiF LiF 3000 2500 2000 1500 Li2Si2O 5 SiO 2 1000 500 SiO 2 Li2Si2O 5 Li2Si2O 5 SiO 2 SiO 2 10 15 20 25 30 35 40 45 50 55 60 65 70 2-Theta-Scale 2000 B) LiF LiF LiF 1500 1000 500 C ac O3 CaCO 3 CaCO 3 CaCO 3 CaCO 3 C ac O3 C ac O3 10 15 20 25 30 35 40 45 50 55 60 65 70 2-Theta-Scale 2-7. LiF:Mg,Cu,Na,Si XRD. A), B). (X-ray diffraction patterns of LiF:Mg,Cu,Na,Si. A) powder. B) sintered pellet.)
3. KLT-300(LiF:Mg,Cu,Na,Si) TL TL, TLD TL.. TLD TLD. TLD LiF:Mg,Cu,P., Mg Cu P. McKeever (1991) Mg Cu P (2.5)., Patil Moharil (1995) Cu + (2.6). Bos (1996) (2.7) Bilski (1996) (2.2) Cu P, Chen (1998) (2.8) Shinde (2001) (2.9) Cu. LiF:Mg,Cu,Na,Si TL LiF:Mg,Cu,P. LiF:Mg,Cu,P P Na Si. Na Si LiF:Mg,Cu,P P. LiF:Mg,Cu,Na,Si TL, LiF:Mg,Cu(MC), LiF:Cu,Na,Si(CNS), LiF:Mg,Na,Si(MNS) LiF:Mg,Cu,Na,Si(MCNS) TL (glow curve), TL 300-800 nm,, TL 3.. 3 TL TL 3 TL,.
. GPIB. SPEX 1681 SPEX CD2A, RS-232C. A/D. 2-8 3 TL. 300-800 nm 1 (scan) 6.2 80 6nm. 2.5. 300 nm ->800 nm -> 300 nm -> 800 nm.,,, 3. Sample Monochromator SPEX 1681 CD-2A TC PMT Power Controller KEITHLEY 195A KEITHLEY 617 Computer(Windows) 2-8. 3 TL. (Schematic diagram of 3-D TL spectra measuring system.) (1) TL SPEX 1681(Spex, USA) 150 gr/mm 6.2 300-800 nm. 2-9. SPEX 1681 150 gr/mm (dispersion) 20.0 nm/mm. TL, 1.0 mm (resolution) 20 nm, He-Ne
30 nm. 2-9.. (Schematic diagram of the spectrometer.) (2) TL. TL. 300-800 nm 6.2 3 0.5. 2-10.,. 200 100 V 50 W 10. 1 40 V Cu-Constantan 1 V KEITHLEY 195A GPIB. (power controller) 3kW slidac 0 140 V
. 12bit D/A Converter. 2-10.. (Flow diagram of temperature control.) (3) TL. HAMAMATSU R928. na electrometer., 6.2 10 nm 50 electrometer. electrometer(keithley 617) A/D.. TL 3 TL 2-11 MC, CNS MNS MCNS. TL. 2-2 MCNS 1, MC 0.311, CNS 0.031, MNS 0.028., Mg Cu TL
. Mg, 5. Mg 2.. Mg LiF. LiF:Mg,Cu,P Mg McKeever (2.5) Bilski (2.2). Nomalized TL Intensity LiF:Mg,Cu,Na,Si LiF:Cu,Na,Si LiF:Mg,Cu LiF:Mg,Na,Si 50 100 150 200 250 300 Temperature(C) 2-11. MCNS, MC, MNS CNS.. (The normalized TL glow curves for the samples: MCNS, MC, MNS and CNS.) 2-2. MCNS, MC, CNS MNS TL. (The relative TL intensities of the MCNS, MC, CNS and MNS samples.) LiF:Mg,Cu,Na,Si LiF:Mg,Cu LiF:Cu,Na,Si LiF:Mg,Na,Si 1 0.311 0.031 0.028
2-12 2-15 MCNS, CNS, MC MNS 0.4 /sec TL 3. MCNS 380 nm 360 nm. Na Si MC MCNS 380 nm 360 nm. Cu MNS 400 nm 360 nm. Mg CNS, TL 340 nm., TL. 2-16 MCNS 107, 159, 204, 240 TL. 355 nm, 385 nm, 440 nm 3, 385 nm 355 nm (240 ) 355 nm. 204 385 nm. 2-17 Mg CNS, 120 MCNS. 120 335 nm 385 nm 2. TL MCNS. 2-18 Na Si MC, 100, 154, 204, 240. 355 nm, 385 nm, 441 nm 3, MCNS 385 nm 355 nm 355 nm. Na Si
. 2-19 Cu MNS,. 355 nm, 401 nm, 441 nm Cu 385 nm. MCNS 385 nm Cu. Patil Moharil (2.6) LiF:Mg,Cu,P TL Cu + TL. Cu LiF:Mg,P TL 405 nm LiF:Mg,Cu,P 385 nm.. Bos Cu 387 nm Cu 352 nm Cu (2.7), Chen Stoebe EXAFS(extended X-ray absorption fine structure) LiF:Mg,Cu,P Cu + (2.8). McKeever, Bos, Patil Moharil, Chen Stoebe., LiF;Mg,Cu,Na,Si TL Mg, Cu 385 nm Na Si. LiF:Mg,Cu,X TL Mg Cu, X X TL.
0.6 0.5 TL Intensity(arb. unit) 0.4 0.3 0.2 0.1 0.0 250 200 150 Temperature( o C) 100 50 300 400 500 600 700 Wavelength(nm) 800 300 250 Temperature(C) 200 150 100 50 300 400 500 600 700 800 Wavelength(nm) 2-12. MCNS TL 3. 300-800nm, 0.4 300. (Isometric plot and contour plot of the TL spectra from the MCNS sample. The wavelength was scanned from 300 to 800 nm, while the temperature was raised from room temperature to 300 C at the heating rate of 0.4 C/sec.)
0.06 0.05 TL Intensity(arb. unit) 0.04 0.03 0.02 0.01 0.00 250 200 Temperature(C) 150 100 50 300 400 500 600 Wavelength(nm) 700 800 300 250 Temperature(C) 200 150 100 50 300 400 500 600 700 800 Wavelength(nm) 2-13. CNS TL 3. (Isometric plot and contour plot of the TL spectra from the CNS sample.)
0.30 TL Intensity(arb. unit) 0.25 0.20 0.15 0.10 0.05 0.00 800 250 Te mp era 150 tur e(c ) 700 200 600 500 100 400 50 vel Wa 300 ) (nm h t eng 300 Temperature(C) 250 200 150 100 50 300 400 500 600 700 800 Wavelength(nm) 그림 2-14. MC 시료의 TL 스펙트럼의 3차원 그래프와 등고선형 그래프. (Isometric plot and contour plot of the TL spectra from the MC sample.) - 100 -
0.06 TL Intensity(arb. unit) 0.08 0.04 0.02 800 0.00 700 250 ) (nm h t g 500 len ve a W 600 200 150 Te mp era 100 tur e(c ) 400 50 300 300 Temperature(C) 250 200 150 100 50 300 400 500 600 700 800 Wavelength(nm) 그림 2-15. MNS 시료의 TL 스펙트럼의 3차원 그래프와 등고선형 그래프. (Isometric plot and contour plot of the TL spectra from the MNS sample.) - 101 -
5 4 3 2 1 0 355 385 240 o C TL Intensity (arb. unit) 40 30 20 10 0 4 3 2 1 0 385 355 385 355 440 440 204 o C 159 o C 3 2 385 107 o C 1 0 355 440 300 350 400 450 500 550 600 Wavelength (nm) 2-16. MCNS. (Analysis of the spectra at each peak temperature of the TL glow curve of MCNS sample.) TL Intensity (arb. unit) 5 4 3 2 1 0 335 385 120 o C 300 350 400 450 500 550 600 Wavelength (nm) 2-17. CNS. (Analysis of the spectra at each peak temperature of the TL glow curve of CNS sample.)
0.02 355 240 o C 0.01 385 0.00 TL Intensity (arb. unit) 0.2 0.1 0.0 0.02 0.01 0.00 385 355 385 355 440 440 204 o C 154 o C 0.03 0.02 385 100 o C 0.01 0.00 355 440 300 350 400 450 500 550 600 Wavelength (nm) 2-18. MC. (Analysis of the spectra at each peak temperature of the TL glow curve of MC sample.) TL Intensity (arb. unit) 2.0 1.5 1.0 0.5 0.0 6 4 2 355 355 401 401 441 441 253 o C 208 o C 0 300 350 400 450 500 550 600 Wavelength (nm) 2-19. MNS. (Analysis of the spectra at each peak temperature of the TL glow curve of MNS sample.)
4. TL. (time constant). (2-1) (fading rate). TLD, TLD. TL, (2.10)... (general approximation method).. thermal bleaching.. (computerized glow curve deconvolution: CGCD) TL. LiF:Mg,Cu,Na,Si TL 2-20 2-3., TL 137 Cs - 10-2 Gy 10 /sec 300. 2-20
,., LiF:Mg,Cu,Na,Si TL 6. 2-3,,. 2.40 ev, 3.50 10 24 sec -1. 6.63 10-5 cm 3 /sec 1. TL Intensity(arb. unit) 319 369 419 469 519 569 Temperature(K) 2-20. LiF:Mg,Cu,Na,Si TL.. (Computerized glow curve deconvolution for the LiF:Mg,Cu,Na,Si TL detector. The scattered curve is measured data.)
2-3. CGCD TL. (The TL parameters of each deconvoluted glow curve, determined by executing the CGCD method.) Peak number Peak temperature(k) Activation energy (ev) Frequency factor (sec -1 ) (cm 3 /sec) 1 355 1.19 1.96 10 17 9.61 10-4 2 398 1.38 5.66 10 17 2.08 10-2 3 449 1.41 5.90 10 15 3.10 10-5 4 491 2.40 4.48 10 24 6.63 10-5 5 519 2.28 3.50 10 24 8.12 10-2 6 541 2.13 1.00 10 20 2.07 10-3 5. LiF:Mg,Cu,Na,Si TL. IEC (2.11) KLT-300 TL.. (sensitivity) TLD TL (2.12). TL,. TLD TLD-100(LiF:Mg,Ti). TLD. (2-2)
,, TLD-100 TLD. KLT-300 TL, TLD-100 5 TLD-100 400 1 100 2, KLT-300 TL 5. 137 Cs -, 10-2 Gy, 10 TL,., LiF:Mg,Cu,Na,Si TL. 28.6. 2-21 TLD-100 KLT-300 TL. TL Intensity(arb. unit) 12000 10000 8000 6000 4000 2000 LiF:Mg,Cu,Na,Si TLD-100(LiF:Mg,Ti) x10-1 0 0 50 100 150 200 250 300 Channel number 2-21. KLT-300 TLD-100. (The glow curves of KLT-300 and TLD-100.). (dose response) TL (2.12).
TLD, TLD (TLD-100 10Gy ) (supralinear)- (sublinear)- (saturate) -.. (2-3),. TL. TLD Gy.,. KLT-300 TL, 10 10, 137 Cs 10-6, 10-5, 10-4, 10-3, 10-2, 10-1, 1, 10, 20 30 Gy. 2-22. 10-4 Gy,, 2-4 2-23. 10-4 Gy 10 Gy, 10 Gy. 10-6 Gy 10-5 Gy., TL CGCD(computerized glow curve deconvolution).
10 10 10 9 10 8 TL Intensity(arb. unit) 10 7 10 6 10 5 10 4 10 3 10 2 1E-7 1E-6 1E-5 1E-4 1E-3 0.01 0.1 1 10 100 Dose(Gy) 2-22. KLT-300. (Dose response of KLT-300 TL detector as a function of absorbed dose.) 1.4 1.2 1.0 f(d) 0.8 0.6 0.4 0.2 0.0 1E-4 1E-3 0.01 0.1 1 10 Dose(Gy) 2-23. KLT-300. (Relative dose response function of KLT-300 TL detector.)
2-4. KLT-300. (Relative dose response function of KLT-300 TL detector.) Dose(Gy) 10-4 10-3 10-2 10-1 1 10 20 30 1.03 1.00 0.99 0.99 1.00 0.99 0.96 0.94. (energy response) TL TLD... ( -, x- ), ( ) (mass energy absorption coefficient) (2.12). (2-4) (linear absorption coefficient).. (2-5)., (pair production), (Compton scattering) (photoelectric effect)., Z
. 15 kev, 15 kev 10 MeV. 10 2 kev., (1.25 MeV 60 Co - 662 kev 137 Cs - ) (relative energy response: RER). (2-6) RER 1. TLD (effective atomic number) RER 1, TLD RER, (energy correction filter) RER 1. KLT-300 9 6, 20 118 kev ANSI (2.13) x- (2.14). 662 kev 137 Cs -. 20, 35, 53, 73 118 kev x- 5 10-2 Gy, 1 662 kev 137 Cs - 10-2 Gy. 2-5 2-24. 66 kev 137 Cs -. 53 kev 1.004, 20 kev 0.825. IEC 137 Cs 60 Co ±30 %. KLT-300 TL. KLT-300 TL TLD-100, LiF:Mg,Cu,P 73 kev 118 kev
. 1.4 LiF:Mg,Cu,Na,Si MCP-N(LiF:Mg,Cu,P) TLD100(LiF:Mg,Ti) Relative TL Intensity(arb. unit) 1.2 1.0 0.8 0.6 10 100 Effective Photon Energy(keV) 2-24. KLT-300. (Relative energy response of LiF:Mg,Cu,Na,Si TL detector.) 2-5. KLT-300. (Relative energy response of KLT-300 TL detector.) Photon energy(kev) 20 35 53 73 118 662 0.825 0.991 1.004 0.920 0.887 1.00. (reproducibility) TLD,,. TL, TL.
,. IEC 10 (coefficient of variation) 0.075. KLT-300 10, 10. 137 Cs - 10-2 Gy, 135 10 10 245. 245 10. IEC (each dosimeter seperately) 10 (all dosimeter collectively)... 10, 10. (2-7) (confidence interval).,. (2-8). LiF:Mg,Cu,Na,Si TL 10 10 (coefficient of variation), (each
dosimeter separately) 10 (all dosimeters collectively) 2-6. 0.01523 0.00495, 0.0054 IEC. 2-25, TL. 2-6. KLT-300. (Reproducibility of KLT-300 TL detector.) Each dosimeter separately Dosimeter ID D01 D02 D03 D04 D05 D06 D07 D08 D09 D10 Coefficient of variation 0.00894 0.00497 0.01523 0.0046 0.00731 0.00866 0.00859 0.00891 0.00495 0.00964 All dosimeters collectively Coefficient of variation 0.0054
1.2 1.0 TL Intensity(arb. unit) 0.8 0.6 0.4 0.2 0.0 2 4 6 8 10 Reuse cycles 2-25. KLT-300. (Reproducibility of KLT-300 TL detector.). (lower limit of detection : LLD), (detection threshold). TLD TL (noise), Student's (2.12)., (2-9).,, Student's 2-7.. KLT-300 10 137 Cs - 10-3 Gy 5
. 5 (Reader calibration factor : RCF). 10 RCF Gy.. Harshaw 4500(Harshaw Bicron, USA), KLT-300 70 ngy. 2-7. Student's. (Student's distribution.) 2 3 4 5 6 7 8 9 10 15 20 25 30 40 60 120 12.71 4.30 3.18 2.78 2.57 2.45 2.37 2.31 2.26 2.15 2.09 2.06 2.05 2.02 2.00 1.98
3 1..... ICRU (3.1) 5 %.. (3.2),... /.. (, W/e S w,air ) (, P u, k m k att ) IAEA 277 (3.3). IAEA (3.4). 100 kv X-,
100 kv X-, 0.66 MeV ( 5 MeV E 0 50 MeV).. ICRU.. D = de/dm (3-1) de dm. (kerma, kinetic energy released in material). K = de tr /dm (3-2) de tr dm. (X). X = K air (1-g)/(W/e) (3-3) K air, g, W/e. IAEA (3.3). ICRU 37 W/e = 33.97 ± 0.06 J C -1..
(Electrometer). (1) 100 kv 300 kv X- ( X- ), Cs-137 60-60, X- 0 10 MeV. 0.1 g cm -2 ( 1 mm) Chamber wall X- ±2 %. Co-60 build-up cap chamber wall build-up cap 0.4 g cm -2 0.6 g cm -2. (Cylindrical chamber(thimble type)). Chamber 0.1 1 cm 3 7 mm, 25 mm. Chamber wall buildup cap air cavity. 3-1. = 10 MeV Plane parallel chamber 5 MeV chamber. 5 10 MeV cylindrical chamber 1 2 % 10 MeV plane parallel chamber. Plane parallel chamber 1 mm Chamber plate 2 mm, Collecting electrode 20 mm Guard electrode. X- Chamber(12 kv 70 kv) backscatter.
3-1.. (Characteristics of ionization chambers used in radiotherapy dosimetry.) Internal Internal Wall Length Radius material (mm) (mm) Cap material CAPINTEC 0.07 cm 3 PR-05P minichamber 6.0 2.0 C-552 Polystylene CAPINTEC 0.14 cm 3 PR-05 minichamber 12.0 2.0 C-552 Polystylene CAPINTEC 0.65 cm 3 PR-06C Farmer type 22.0 3.2 C-552 C-552 CAPINTEC 0.65 cm 3 PR-06C Farmer type 22.0 3.2 C-552 Polystylene CAPINTEC 0.65 cm 3 PR-06C Farmer type 22.0 3.2 C-552 PMMA CAPINTEC 0.60 cm 3 (AAPM) 23.8 3.25 Graphite PMMA EXRADIN 0.5 cm 3 Al (2 mm cap) 9.7 4.7 C-552 C-552 EXRADIN 0.5 cm 3 Al (4 mm cap) 9.7 4.7 C-552 C-552 EXRADIN 0.5 cm 3 T2 9.7 4.7 A-150 A-150 EXRADIN 0.05 cm 3 T1 min Shonka 7.2 2.0 A-150 A-150 FAR WEST TECH 0.1 cm 3 IC-18 9.5 2.3 A-150 A-150 FZH, 0.4 cm 3 TK 01 waterproof 12.0 3.5 Delrin Delrin NE 0.20 cm 3 2515 7.0 2.95 Tufnol PMMA NE 0.20 cm 3 2515/3 7.0 3.15 Graphite PMMA NE 0.20 cm 3 2577 8.3 3.15 Graphite Delrin NE 0.60 cm 3 Farmer 2505 '54-'59 a 24.0 2.95 Tufnol PMMA NE 0.60 cm 3 Farmer 2505 '59-'67 a 24.0 2.95 Tufnol PMMA NE 0.60 cm 3 Farmer 2505/A '67-'74 a 24.0 2.95 Nylon 66 PMMA NE 0.60 cm 3 Farmer 2505/3, 3A '71-'79 a 24.0 3.15 Graphite PMMA NE 0.60 cm 3 Farmer 2505/3, 3B '74-present a 24.0 3.15 Nylon 66 PMMA NE 0.60 cm 3 Guarded Farmer 2571 24.0 3.15 Graphite Delrin NE 0.60 cm 3 Robust Farmer 2581(PMMA cap) 24.0 3.15 A-150 PMMA NE 0.60 cm 3 Robust Farmer 2581 (polystyrene cap) 24.0 3.15 A-150 Polystylene NE 0.325 cm 3 NPL Sec Std 2561 9.2 3.7 Graphite Delrin PTW 0.6 cm 3 23333 (3 mm cap) 21.9 3.05 PMMA PMMA PTW 0.6 cm 3 23333 (4.6 mm cap) 21.9 3.05 PMMA PMMA PTW 0.4 cm 3 233331 21.9 2.35 PMMA PMMA PTW 0.3 cm 3 Normal M233332 18.0 2.5 PMMA PMMA PTW 0.1 cm 3 Transit M233331 22.0 4.0 PMMA PMMA PTW 0.3 cm 3 Waterpr M2333641 15.1 2.75 PMMA PMMA VICTOREEN 0.1 cm 3 Radocon 555 4.3 2.5 Delrin VICTOREEN 0.3 cm 3 Radocon 550 23.0 2.4 Polystylene PMMA VICTOREEN 0.30 cm 3 30-348 18.0 2.5 PMMA PMMA VICTOREEN 0.60 cm 3 30-351 23.0 3.05 PMMA PMMA VICTOREEN 1.00 cm 3 30-349 22.0 4.0 PMMA PMMA SSI GRAPHITE 17.9 4.0 Graphite Graphite SSI A-150 17.9 4.0 A-150 A-150
(2) Electrometer charge( current) ( 10 14 ) electrometer display 4 digit resolution 0.1 % resolution. ± 0.5 % chamber chamber. (3) reference (, ). ( blocks) Charge build-up chamber signal. field size 5 cm..., (perturbation factor),.. (1) ( ),. ( 3-1 a).
E max,a :, E p,a : (most probable energy) a : half maximum (spread), a :. a, 0 z, z 4. E max,z, E p,z, z, z a o z E p,o E p,o o. E p,o Isodose curve Practical range R p. 3-1. : (a) ; (0) ; (z) z. (Electron energy spectra and their parameters.)
E p,o field size SSD. range(r t ) 85 % range E p,o. E p,o beam beam flattening filter, monitor chamber E p,o. ( ) Range - Energy E p,o o range Range 3-2 R p R 50 ( ). R p : tail R 50 : 50 %, o 15 MeV 12 cm x 12 cm size 20 cm x 20 cm size. 3-2.. (An electron beam absorbed dose distribution in a water phantom.) o 10 MeV
range plastic slap.. (3-4) R w, R pl = ranges(r t, R 50, R p, etc) in water and plastic = Linear continuous-slowing-down range( range) = ICRU 35 o 10 MeV Parallel plane chamber (Effective point of measurement, 3-5).. 2 E p,o = C 1 + C 2 R p + C 3 R p C 1 : 0.22 MeV, C 2 : 1.98 MeV cm -1, C 3 : 0.0025 MeV cm -2 o = C 4 R 50 : beam size, 5 E 35 MeV C 4 : 2.33 MeV cm -1 z E o (1 - z/r p ) E o o (2) Cs-137 Co-60 Cs-137 0.662 MeV, Co-60 1.17 MeV, 1.33 MeV 1.25 MeV. (3) X- Target, flattening. X- (, ).
,. X- ( potential"). depth dose data, isodose charts, stopping power ratio, perturbation correction 20 cm, 10 cm 10 x 10 cm field size. TPR Tissue-Phantom ratio. 3-3. 3-3.. (a) - (SCD). (b) - (SSD). (The two experimental set-ups to determine the quality of photon beams.)
. 1 2.,. air kerma. (1) (PSDL)., ( Co-60 ) air kerma, K air,c (c : calibration). (1-g) (W/e) c. - g : Co-60 0.3 %, X- K a. - W/e : 33.97 J C -1 for dry air (2) (SSDL) 3-4. - PSDL user - Bragg-Gray ( 3-4 (f) (g)).. Co-60 Calibration quality, c. Cs-137, Co-60,, User's quality, u. PSDL Air kerma Exposure factor SSDL. SSDL N k. Co-60 Free-in-air Source-to-chamber(chamber ) 1 m, 10 x 10 cm field size Source field size
. Source collimator 1 m SCD( SSD).
3-4. PSDL, SSDL. (The calibration chain for electron and high energy photons from PSDL to SSDL to user.)
Air kerma. N k = K air,c /M c (3-5) calibration quality. ( Co-60, index c). (1) Absorbed dose to air kerma factor Air kerma, K air,c,. N D,c = : Absorbed dose to air kerma factor N D,c = N D,u = (2) : Bragg-Gray ( ). = K air,c (1-g)K att K m N D,c = N k (1-g)K att K m (3-6) K m : Co-60 (IAEA-277, Table XVIII) K att : Build-up cap ( ) Bragg-Gray P eff (Effective point of measurement of chamber, EPOM). D w (P eff ) = (S w,air ) u P u (3-7)
(S w,air ) : Stopping power ratio water to air 7.2 P u : Perturbation correction factor D w (P eff ) = M u N D (S w,air ) u P u N D,c = N D,u = N D 1.5 %. (perturbation) - Perturbation factor P u - EPOM. EPOM cavity fluence gradient( ) ( 3-5) P P eff air cavity spatial content, P u Section 7.2. Plane parallel chamber. EPOM. 3-5. P( P z ) P eff. (Displacement of the effective point of measurement P eff (depth Zp eff ) from the center P(depth Z p ) of an ionization chamber.)
Z Peff - Z P = 0.5 r (for electron) = 0.75 r (for high energy photon) = 0.5 r (for Co-60) = 0.35 r (for Cs-137) = 0 (for. X- ). (1),,,. (aging, zero- drift, warm-up ) (,,, ).,. 3-2.,. Warm-up : warm-up. (Leakage current) :. (Polarity effect) :.. ( charges).. :.
3-2.. (Reference conditions of the ionization geometry for absorbed dose measurement using an ionization chamber in a phantom.)
P TP = (3-8) P T, Po To (101.3 kpa, 20 ). : A-150 charge. 50 % 15 25 20 % 70 %. Dry air Co-60 K h = 0.997. (Recombination) :.,, charge. Pulse ( ). Two voltage". : V 1 ( bias ), V 2 Q 1, Q 2. V 1 /V 2 3. : Ps V 1. Ps = a o + a 1 (Q 1 /Q 2 ) + a 2 (Q 1 /Q 2 ) 2 : Pulse a i 3-3 Ps 3-6. (2) 3-7. X-. Build-up cap. N D,c (Absorbed dose to air chamber factor),,,. g = 0.003, K att K m = 3-4 N D = N k (1-g)K att K m (3-9)
3-3. V1/V2. (Quadratic fit coefficients for pulsed radiation as a function of the voltage ration V1/V2.) Voltage ratio a 0 a 1 a 2 2.0 2.337-3.636 2.299 2.5 1.474-1.587 1.114 3.0 1.198-0.8753 0.6773 3.5 1.080-0.5421 0.4627 4.0 1.022-0.3632 0.3413 5.0 0.9745-0.1875 0.2135 6.0 0.9584-0.1075 0.1495 8.0 0.9502-0.03732 0.08750 10.0 0.9516-0.01041 0.05909 3-6. Ps. (The correction factor for recombination P s in continuous radiation.)
N D,c D w (P eff ). 3-7.. (Reference water phantom for absorbed dose determination.) ( ) D w (P eff ) = M u N D (S w,air ) u P u (S w,air ) : Spencer-Attix cavity : Berger M. C..(IAEA-277, Table X) P u : Perturbation correction factor(iaea-277, Table XI) : E z.(iaea-277, Table V) P eff :. P eff 0.5r r =, Z Peff - Z P = 0.5 r :.
3-4. k m k att k m k att. (Values for k m, k att and km katt for the ionization chambers.) K m K att K m K att CAPINTEC 0.07 cm 3 PR-05P minichamber 1.002 0.988 0.990 CAPINTEC 0.14 cm 3 PR-05 minichamber 1.002 0.989 0.991 CAPINTEC 0.65 cm 3 PR-06C Farmer type (AE cap) 1.006 0.984 0.990 CAPINTEC 0.65 cm 3 PR-06C Farmer type (polystyrene cap) 0.987 0.990 0.977 CAPINTEC 0.65 cm 3 cap) PR-06C Farmer type (PMMA 0.993 0.990 0.983 CAPINTEC 0.60 cm 3 (AAPM) 0.989 0.989 0.987 EXRADIN 0.5 cm 3 Al (2 mm cap) 1.006 0.985 0.991 EXRADIN 0.5 cm 3 Al (4 mm cap) 1.006 0.976 0.981 EXRADIN 0.5 cm 3 T2 0.965 0.985 0.950 EXRADIN 0.05 cm 3 T1 min Shonka 0.965 0.991 0.957 FAR WEST TECH 0.1 cm 3 IC-18 0.965 0.991 0.956 FZH, 0.4 cm 3 TK 01 waterproof 0.989 0.989 0.978 NE 0.20 cm 3 2515 0.980 0.988 0.968 NE 0.20 cm 3 2515/3 0.991 0.987 0.978 NE 0.20 cm 3 2577 0.994 0.987 0.982 NE 0.60 cm 3 Farmer 2505 '54-'59 a 0.980 0.992 0.973 NE 0.60 cm 3 Farmer 2505 '59-'67 a 0.980 0.990 0.971 NE 0.60 cm 3 Farmer 2505/A '67-'74 a 0.971 0.991 0.962 NE 0.60 cm 3 Farmer 2505/3, 3A '71-'79 a 0.991 0.990 0.981 NE 0.60 cm 3 Farmer 2505/3, 3B '74-present a 0.974 0.991 0.965 NE 0.60 cm 3 Guarded Farmer 2571 0.994 0.990 0.985 NE 0.60 cm 3 Robust Farmer 2581(PMMA cap) 0.975 0.990 0.966 NE 0.60 cm 3 Robust Farmer 2581 (polystyrene cap) 0.969 0.990 0.959 NE 0.325 cm 3 NPL Sec Std 2561 0.995 0.984 0.979 PTW 0.6 cm 3 23333 (3 mm cap) 0.982 0.993 0.975 PTW 0.6 cm 3 23333 (4.6 mm cap) 0.982 0.990 0.972 PTW 0.4 cm 3 233331 0.982 0.990 0.971 PTW 0.3 cm 3 Normal M233332 0.982 0.993 0.975 PTW 0.1 cm 3 Transit M233331 0.982 0.992 0.974 PTW 0.3 cm 3 Waterpr M2333641 0.982 0.992 0.974 VICTOREEN 0.1 cm 3 Radocon 555 0.989 0.990 0.979 VICTOREEN 0.3 cm 3 Radocon 550 0.974 0.991 0.965 VICTOREEN 0.30 cm 3 30-348 0.982 0.993 0.975 VICTOREEN 0.60 cm 3 30-351 0.982 0.993 0.965 VICTOREEN 1.00 cm 3 30-349 0.982 0.992 0.974 SSI GRAPHITE 0.999 0.990 0.989 SSI A-150 0.965 0.990 0.955
( ) D w (P eff ) = M u N D (S w,air ) u P u (S w,air ) : 3-5 : D 20 /D 10. P u : P u factor 3-8 : 0.5 mm. : 1. P eff : 0.75 r (for high energy photon) 0.5 r (for Co-60) 0.35 r (for Cs-137) ( ) X- : 100 300 kev P eff : 0 ( ) D w : M u N k k u ( ) w,air P u N k : air kerma k u : 1. : : X- (IAEA-277, Table XIV) P u : IAEA-277, Table XV : design. ( ) X- D w = M u N D,w : D w : M u N k Bk u ( ) w,air : B : Backscattering factor(iaea-277, Table XVI) k u : 1. IAEA-277, Table XIV
3-5. Stopping Power Ratio Water to Air(S w,air ). (The stopping power ratio water to air at the reference depth as a function of the photon energy.) Beam quality D 20 /D 10 a S w,air Ref. depth 0.50 0.44 1.135 5 0.53 0.47 1.134 5 0.56 0.49 1.132 5 0.59 0.52 1.130 5 0.62 0.54 1.127 5 0.65 0.56 1.123 5 0.68 0.58 1.119 5 0.70 0.60 1.116 5 0.72 0.61 1.111 10 0.74 0.63 1.105 10 0.76 0.65 1.099 10 0.78 0.66 1.090 10 0.80 0.68 1.080 10 0.82 0.69 1.069 10 0.84 0.71 1.059 10 Cs-137 1.136 5 Co-60 1.133 5 a At SSD = 100 cm: obtained from by a fit to experimental data
3-8. P u. (The perturbation factor Pu as a function of the quality of photon beams for different chamber wall materials.).. k m = S air,m ( en / ) m,air : Build-up cap m 3-4 3-6 = S air,wall ( en / ) wall,air + (1- )S air,cap ( en / ) cap,air : : S air,m ( en / ) m,air air cavity 3-9 1- : Build-up cap air cavity Electrode Build-up cap Central electrode Pcel. Pcel 3-7.
3-6. k m (= s air,m ( en / ) m,air ). (Valuef the the ractor k m (= s air,m ( en / ) m,air ).) Material s air,m (a) ( en / ) m,air (b) k m A-150 (T.E. plastic) 0.876 1.101 0.965 C-552 (A.E. plastic) 1.005 1.001 1.006 Delrin (CH 2 O) n 0.925 1.068 0.989 Graphite ( = 1.7 g/ ) 0.998 1.001 0.999 Graphite ( = 2.265 g/ ) 1.000 1.001 1.001 Nylon 66 (C 6 H 11 ON) n 0.875 1.098 0.961 PMMA (perspex, lucite) (C 5 H 8 O 2 ) n 0.908 1.081 0.982 Polystyrene (C 8 H 8 ) n 0.901 1.078 0.971 Tufnol - - 0.976 3-7. Farmer type p cel. (CORRECTION FACTOR p cel for a Farmer type of chamber.) Electrode radius (mm) Electrons Photons (h ) max > 25 MeV 60 Co and photons (h ) max 25 MeV 0.5 1.008 1.004 1.000 1 1.015 1.008 1.000 1.5 1.020 1.010 1.000 2.5 1.032 1.016 1.000
3-9.. (The fraction of ionization due to electrons arising in the chamber wall as a function of wall thickness for the photon beam given by.) air kerma work sheet.
Worksheets for Absorbed Dose Determination WORKSHEET 1 FOR CALCULATING THE ABSORBED DOSE TO AIR CHAMBER FACTOR N D Name : User Date : 1. Ionization chamber Chamber model and serial number : NE 2505/3A, No. 4075 Cavity inner radius : 3.14 mm Wall material : Graphite ( = 1.82 g/ ), thickness : 0.0655 g/ Buildup cap material : PMMA ( = 1.18 g/ ), thickness : 0.543 g/ total thickness : 0.6085 g/ 2. Calibration laboratory data Calibration laboratory and date : SSDL, 860808 Calibration factor (kerma in air), N k = 9.08 10-3 Gy/scale div given at P O = 101.3 kpa, T O = 20 and 50 R.H. Polarizing voltage : -250 V, field size : 10 10 Source chamber distance : 100 3. Constants W/e = 33.97 J/C, and g = 0.003 (for 60 Co gamma radiation). 4. Determination of k att k m 2 Fraction of ionization due to electrons from chamber wall (IAEA-277 Fig. 15), = 0.53 Stopping power ratio air/wall (IAEA-277 Table XV ), S air,wall = 0.998 Energy absorption coefficient ratio wall/air (IAEA-277 Table XV ), ( µ / ρ en ) wall, air = 1.001 Fraction of ionization due to electrons from buildup cap, (1- ) = 0.47
Stopping power ratio air/cap (IAEA-277 Table XV ), S air,cap = 0.908 Energy absorption coefficient ratio cap/air (IAEA-277 Table XV ), ( µ en / ρ ) cap, air = 1.081 k m = α s air, wall ( µ en / ρ ) wall, air + (1 α ) s air, cap ( µ en / ρ ) cap, air 0.991 = k att = 0.990 k att k m = 0.981 5. Absorbed dose to air calibration factor N D = N K (1-g) k att k m = 0.888 10-2 Gy/div, obtained at 101.3 kpa, 20, 50 R.H.
WORKSHEET 2 FOR CALCULATING THE ABSORBED DOSE TO WATER UNDER REFERENCE CONDITIONS USING ELECTRON BEAMS Name : User Date : 1. Radiation treatment unit : Sagittaire Nominal energy : 19 MeV Depth of the effective point of measurement : 3, Field size : 10 10 at SSD = 100 Nominal dose rate of the accelerator : 200 monitor units/min ( z z 0.5r) p eff p = 2. Ionization chamber Model and serial number : NE 2505/3A, No. 4075 Inner radius : 3.14 mm, wall material and thickness : Graphite, 0.0655 g/ Absorbed dose to air chamber factor : N D = 0.888 10-2 Gy/div given at P O = 101.3 kpa, T O = 20, 50 R.H. Polarizing voltage : -250 V Response change as compared to calibration date derived from checking against radioactive source : O.K. within 0.2 3. Electrometer reading correction Pressure, P = 100.3 kpa Temperature, T = 24.3 Mu o = 0.9976 div / m. u., monitor setting : 200 m. u. Reading, P (273.2 + ) = o T = 1.025 P (273.2 + T ) Humidity correction, k h = 1.00 Recombination correction (IAEA-277 Table or ) V 1 = 250 V, V 2 = 83.33 V, M 1/M 2 =1.095, p s = 1.054 P TP o u u ptpkh ps = M = M o 1.078 div / m. u.
Electron fluence correction plastic to water (IAEA-277 Table ), h m = 1.0 M u,w = M u h m = 1.078 div/m.u. 4. Absorbed dose to water Ranges obtained by measurement at SSD = 1m with absorbed dose curves R 50 = 7.4, R p = 9.0 Phantom material (plastics can only be used if a) water b) plastic Eo 10 MeV ) Ranges converted to ranges in water (Eq.(1), IAEA-277 Table ) R 50 =, R p = Most probable energy at the surface 2 p, o p 0.0025 Rp E = 0.22 + 1.98 R +, E, o = p 18. 24 MeV Mean energy at the surface (IAEA-277 Table ), z / R p = 0.333, E z / Eo ( Table V ) = 0. 596 Eo = 17. 56 MeV Mean energy at depth (z = 3 cm), E z = 10. 47 Stopping power ratio water/air (IAEA-277 Table ), S w,air = 0.999 Perturbation factor (IAEA-277 Table ), P u = 0.981 MeV D w ( P eff ) = M u N D 2 sw, air pu = 0.938 10 Gy / m. u.
WORKSHEET 3 FOR CALCULATING THE ABSORBED DOSE TO WATER UNDER REFERENCE CONDITIONS USING HIGH ENERGY PHOTON BEAMS Name : User Date : 1. Radiation treatment unit : Theratron 80, 60 Co Nominal accelerating potential : MV Depth in water of the effective point of measurement : 5 cm, ( z z 0.5r, Fig.11) p eff p = Field size : 10 10 at SSD = 80 cm Nominal dose rate of the accelerator : monitor units/min 2. Ionization chamber Model and serial number : NE 2505/3A, No. 4075 Inner radius : 3.14 mm, wall material and thickness : Graphite, 0.0655 g/ Absorbed dose to air chamber factor : N D = 0.888 10-2 Gy/div given at P O = 101.3 kpa, T O = 20, 50 R.H. Polarizing voltage : -250 V Response change as compared to calibration date derived from checking against a radioactive source : O.K. within 0.1 3. Electrometer reading correction 2 min Reading, 2 Mu o = 76.43 div / min, monitor setting : m. u. Pressure, P = 100.7 kpa P (273.2 + ) = o T PTP = 1.019 Temperature, T = 23.8 P (273.2 + To ) Humidity correction, k h = 1.000 Recombination correction (IAEA-277 Table or, or Fig.13) V 1 = 250 V, V 2 = 83.3 V, M 1 /M 2 =1.001, p s = 1.000 o Mu = Mu ptp kh ps = 2 77.88 div / min
4. Absorbed dose to water 20 10 or D20 / D10) = for 10 10 TPR ( cm at SCD = 1 m (SSD 1 m) Stopping power ratio water/air (IAEA-277 Table ), S w,air = 1.133 Perturbation factor ((IAEA-277 Fig. 14), P u = 0.991 2 D ( P ) = M N s, p = 77.65 10 Gy / min w eff u D w air u 2 Quality of the beam, 2
WORKSHEET 4 FOR CALCULATING THE ABSORBED DOSE TO WATER UNDER REFERENCE CONDITIONS USING X-RAYS Name : User Date : 1. Radiation treatment unit : Nominal tube potential 200 kv, filtration : 1 mm Cu, 3.8 mm Al Nominal tube current : 10 ma Applicator/field size : 10 cm 10 cm at FSD = 80 cm Quality of the beam to be used, HVL = 1.6 mm of Cu 2. Ionization chamber 2a. Plane parallel (low energy X-rays, 10-100 kv) Model and serial number : Calibration factor at HVL = mm of (Nominal kv =, filtration : ) N K = Gy/div, N D,w = Gy/div given at P O = kpa, T O =, R.H. Polarizing potential : V, field size : Source-chamber distance : cm Response change as compared to calibration date derived from checking against a radioactive source : 2b. Cylindrical (medium energy X-rays, 100-300 kv) Model and serial number : PTW M23331 No. 307 Calibration factor at HVL = 1.6 mm of Cu (Nominal kv = 200, Filtration : 3.8 mm Al 1 mm Cu) N K = 28.78 10 6 Gy/C, given at P O = 101.325 kpa, T O = 20, 60 R.H. Polarizing potential : +500 V, Field size : 10 cm 10 cm
Source-chamber distance 100 cm Response change as compared to calibration date derived from checking against a radioactive source : O.K. within % 3. Electrometer reading correction Reading, M o u = 6.072 10 11 C / min Pressure, P = 101.84 kpa Temperature, T = 21.3 Humidity correction, k h = 1.000 Recombination correction ((IAEA-277 Fig. 13) : V 1 = V, V 2 = V, M 1/M 2 =, p s = 1.000 P TP P (273.2 + ) = o T = 0.9994 P (273.2 + T ) o M u = M o u p TP k h p s = 6.068 10 11 C / min 4. Absorbed dose to water 4a. Low energy X-rays (surface) (i) N D,w available D w = M u N D,w = Gy/min (ii) N k available (a) Energy absorption coefficient ratio water/air (IAEA-277 Table ), (b) Backscatter factor (IAEA-277 Table ), B = (c) Correction for spectral dependence, k u = D w = Mu NK B ku en w, air 4b. Medium energy X-rays (5 cm depth) (a) Energy absorption coefficient ratio water/air (IAEA-277 Table ), ( µ / ρ en w, air ( µ / ρ) = Gy / min (b) Perturbation factor (IAEA-277 Table ), P u = 1.04 (c) Correction for spectral dependence, k u = 1.000 D w ) = ( µ / ), = 1.074 ρ en w air 3 = M N ( µ / ρ), P k = 1.95 10 Gy / min u K en w air u u
2.. (1) ICRU 24 (3.1), X, ICRU ±5 %. ICRU ±2 % (1976). 95 % 2. 5 % 1 2.5 %. 1 5 %. ±5 %. (3-D ).,, 3-D., K air, N D,air ( N gas ), D w, D w. Co-60 N k D w., k m k att. N k N D,air ( N gas ).
IAEA-277 (3.3) 381 (3.5) 3 4 % (IAEA-277, page 70).. Reich (3.6).. (Graphite)... (PSDL)., (chemical dosimetry) (water and graphite calorimeter). water calorimeter (perturbation). PSDL Co-60 N D,W. (SSDL) PSDL. Co-60 SSDL.. Co-60
.. K air. kw X- IAEA-277. X- N d,w PSDL PSDL. X- N d,w X- PSDL SSDL protocol K air.. (2) (3.4).. ( ) (Reduced Uncertainty) 20 PSDL. K air. K air.. K air.. 3-10
Co-60 N D,W /N k. 0.8 % BIPM (3.7).. Co-60.. 3-10.. (The ratio of Co-60 calibration factor N D,w /N K to demonstrate chamber to chamber variation for a large number of cylindrical chambers commonly used in radiotherapy dosimetry.)
( ) Co-60 K air., 0.7 %.. ( ) K air K air.. (2) (a) X- : 100 kv, HVL 3 mm Al (b) X- : 80 kv, HVL 2 mm Al (c) Co-60 (d) ( ) : 1 50 MeV, TPR 20,10 : 0.5 0.84. 1) Calorimeter, 2) (chemical dosimetry), 3) 3. PSDL. PSDL Co-60 PSDL, kv X-.
. - graphite cavity chamber Bragg-Gray.. - Graphite calorimeter - Water calorimeter - Water calorimeter with Frick transfer dosimeter - Frick standard kv X- (extrapolation). 3-11(a) Co-60. PSDL. Co-60 K air 3-11(b). PSDL K air graphite cavity chamber 3-8 K air. 3-8. BIPM. (Primary standards used in the comparisons of absorbed dose to water at the BIPM.)
3-11. Co-60 Ka. ((a) Results of comparison of standards of absorbed dose to water at the BIPM in Co-60 beam. (b) Results of comparison of standards for air kerma at the BIPM in Co-60 beam.)
. N D,W Co-60,. (1) Qo Z ref D W,Qo = M Qo N D,W,Qo (3-10). M Qo, N D,W,Qo.. ( ) (Reference condition) /.. ( ),,,,. ( ) (Influence quantities).,, (aging, zero drift, warm-up) (,, )., Co-60.
. k i (k i ). 4. Qo k Q,Qo. (2) k Q,Qo Qo Q D W,Q = M Q N D,W,Qo k Q,Qo (3-11) k Q,Qo Qo Q M Q. k Q,Qo. k Q,Qo = (3-12) k Q,Q0 PSDL.. k Q,Qo = (3-13), S w,air Spenccer-Attix /, W air, P Q (perturbation factor) Bragg-Gray P wall, P cav, P cel P dis. P wall : Chamber wall medium( )
P cav : chamber medium( ) P cel : central electrode P dis : P eff. K air. X- Bragg-Gray N D,W,Q k Q,Qo. (3) N k N k - N D,air N D,w. N D,w,Qo = N D,air (S w,air ) Qo P Qo (3-14) N D,w,Qo N D,w N k N D.w.. (1). (a) Co-60 Qo Q k Q,Qo. PSDL. X- Q. (b) Co-60 N D,w,Qo k Q,Qo ( 3-12).
.,,,. 3-12 NE 2561 k Q. (Mean values of k Q at various photon beams measured at NPL in the UK for secondary ion chamber NE 2561 ( ) and NE 2611 ( ). The solid line is a sigmoidal fir to the experimental data. The values of k Q are normalized to a TPR 20,10 of 0.568(Co-60 at the NPL). Caluated values of k Q for these chambers are included for comparison ( ).)
(2).. (a) (b) (electrometer) (c) (waterproof sleeve) ( ) (a) : 80 kv X-, Co-60,, 10 MeV,.( 3-9 ) -. - : 0.1 1 cm 3 -. 7 mm 25 mm. (b) (central electrode). -. - Air cavity (c) ( ). - Graphite :, - : (d) : ( 10 MeV ),
X- SOBP(Spread-out Bragg Peak). - backscatter. - perturbation.. P eff.. Cavity cavity 5 Pancake". ( ) - : Electrometer Power supply. Current charge - 4 digit resolution(, 0.1 % resolution) - 1 response ±0.5 % (Long term stability) - - (+, -). ( ) -. - 4 5 cm. - 5 g/cm 2 ( X- 10 g/cm 2 ). - 10 MeV, X-..(, )
3-9.. (Characteristics of cylindrical ionization chamber types.) Ionization chamber type Cavity volume (cm 3 ) Cavity radius (mm) Wall material Build-up material Capintec PR-05P mini 0.07 2.0 C-552 Polystyrene N Water -proop Capintec PR-06C/G 0.65 3.2 C-552 Polystyrene N Exradin A2 Spokas (2mm cap) 0.53 4.8 C-552 C-552 Y Exradin A1 mini Shonka (2mm cap) 0.05 2.0 C-552 C-552 Y Far West Tech IC-18 0.1 2.3 A-150 A-150 N FZH TK 01 0.4 3.5 Delrin Delrin Y Nuclear Assoc. 30-750 0.03 2.0 C-552 Y Nuclear Assoc. 30-749 0.08 3.0 C-552 Y Nuclear Assoc.30-744 0.13 3.0 C-552 Y Nuclear Assoc.30-716 0.25 3.0 C-552 Delrin Y NE 2515 0.2 3.0 Tufnol Delrin Y NE 2505 Famer 0.6 3.0 Tufnol PMMA N NE 2505/A Famer 0.6 3.0 Nylon 66 PMMA N NE 2571 Famer 0.6 3.2 Graphite Derin N PTW 23323 micro 0.1 1.6 PMMA PMMA Y PTW 23331 rigid 1.0 4.0 PMMA PMMA N PTW 23332 rigid 0.3 2.5 PMMA PMMA N PTW 30001 Farmer 0.6 3.1 PMMA PMMA N SNC 100730 Farmer 0.6 3.5 PMMA PMMA N Victoreen Radocon 550 0.3 2.5 Delrin N Victoreen Radocon 555 0.1 2.4 Polystyrene PMMA N Victoreen 30-351 0.6 3.1 PMMA PMMA N Scdx-Wellhofer IC 05 0.08 3.0 C-552 Y Scdx-Wellhofer IC 15 0.13 3.0 C-552 Y Scdx-Wellhofer IC 25 0.25 3.0 C-552 Y
( ) -. - PMMA (1.0 mm ) 10. - 0.1 0.3 mm gap. - buildup. -. -. PTW W30006 1 mm N D,W. -. ( ) Z ref (g/cm 2 ) cavity, (perturbation). Q Qo k Q,Qo.. k Q,Qo. k Q,Qo.. (g/cm 2 ) (cm) x (g/cm 3 ). ( ) PDD Z ref. cavity volume, X-, X- ( Buildup foil).
cavity cavity. Cavity cavity k Q,Qo P cav. Z ref cavity Z ref k Q,Qo P dis,. (.) ( k Q,Qo. - Appendix II ). (.) P dis. Co-60, P dis k Q,Qo. gradient Z ref. Z ref 0.5 r cyl 0.75 r cyl. r cyl cavity. P wall k Q,Qo. Q......
.. X- Z ref. (3) ( ).. Qo 2-3, damage. 6. 5. ( ) Co-60 PSDL SSDL. Co-60 5 g/cm 2 D w 5 g/cm 2 N D,w N D,w = D w /M (3-15). M. Co-60 3-10. ( ) kv X- (1) X-. kv X- PSDL
3-10.. (Reference conditions recommended for the calibration of ion chamber in Co-60 in standard laboratories.) Influence quantity Phantom material Phantom size Source chamber distance (SCD) Air temperatur Air pressure Reference point of the ionization chamber Reference value or reference characteristic Water 30 x 30 x 30 (approximately) 100 20 101.3 kpa For cylindrical chambers, on the chamber axis at the centre of the cavity volume; for plane- parallel chambers on the inner surface of the entrance window, at the centre of the window. Depth in phantom of the reference point of the chamber 5g/ 2 Field size at the position of the reference point of the chamber 10 x 10 Relative humidity 50 % Polarizing voltage and polarity Dose rate No reference values are recommended, but the value used should be stated in the calibration certificate. No reference values are recommended, but the dose rate used should always be stated in the calibration certificate. It should also be stated whether a recombination correction has or has not been applied and, if so, the value should be stated. K air. X- X-. ( ). N D,W,Q N D,W,Qo k Q,Qo.
( ). (4) ( ) Qo N D,W,Qo. 3. D W,Q = M Q N D,W,Qo k Q,Qo (3-16) M Q ki, k Q,Qo Qo Q.. ( ) 4.2.4.... Electrometer 2 power. Charge 2 5 Gy pre-irradiation. 20. Leakage. 0.1 %. leakage (±) 1 %. ( ).
. k i., P TP = (3-17) P T Po To (101.3 kpa, 20 ).... 50 %. 20 80 %. Dry air k h = 0.997 (Co-60). Electrometer electrometer k ele ki k ele nc/rgd (nc/nc). electrometer k ele. sheet k ele 1. (k Q,Qo P eff.). X-..
. k pol. = (3-18) M + M - + - electrometer M (+ -) electrometer... k pol.. k s. Pulsed (3-19) M 1 M 2 V 1 V 2. a i 3-11. k s 1.03.
3-11. V 1 /V 2 k s. (Quadratic fit coefficients for the calculation of k s by the 'Two Voltage' technique in pulsed and pulsed-scanned radiation as a function of the voltage ratio V 1 /V 2.) V 1/V 2 Pulsed Pulsed-scanned a 0 a 1 a 2 a 0 a 1 a 2 2.0 2.337-3.636 2.299 4.711-8.242 4.533 2.5 1.474-1.587 1.114 2.719-3.977 2.261 3.0 1.198-0.875 0.677 2.001-2.402 1.404 3.5 1.080-0.542 0.463 1.665-1.647 0.984 4.0 1.022-0.363 0.341 1.468-1.200 0.734 5.0 0.975-0.188 0.214 1.279-0.750 0.474 (3-20) Continuous (Co-60 ). (3-21) ( X- )... k s. Q Qo. (3-22) Qo, k s,qo 1
pulsed.. Co-60 (1) Dosimetry ( ) 4.2.1. ( ) 4.2.3 4.2.4. Co-60 medium. (t win ) 0.2 0.5 cm. (g/cm 2 ). PMMA PMMA = 1.19 g/cm 3 polestylene = 1.06 g/cm 3 PMMA ( polestylene ) x (t win ). 1.0 mm PMMA. gap (0.1 0.3 mm)... (2) ( ) 3-12. ( ), Z ref, D W. D W = M N D,W (3-23)
M Z ref 3-12 (, electrometer, ). Co-60 timer M. ( ) Z max (Z max ). SSD PDD, SAD TMR. (3) Co-60 Co-60 13-6. 3-12. Co-60. (Reference conditions for the determination of absorbed dose to water in Co-60 gamma ray.) Influence quantity Phantom material Chamber type Reference value or reference characteristics Water Cylindrical or plane parallel Measurement depth, Z ref 5g/ 2 (or 10g/ 2 ) Reference point of the chamber Position of the reference point of the chamber SSD or SCD Field size For cylindrical chambers, on the central axis at the centre of the cavity volume. For plane- parallel chambers, on the inner surface of the window at its centre. For cylindrical and plane-parallel chambers, at the measurement depth. 80 or 100 10 x 10
3-13. Co-60. (Determination of the absorbed dose to water in a 60 Co ray beam.) Determination of the absorbed dose to water in a 60 Co ray beam user Date 1. Radiation treatment unit and reference conditions for D w determination 60 Co therapy unit : Reference phantom : water Set-up : SSD SAD Reference field size : 10 x 10 ( x ) Reference distance : Reference depth Z ref : g/ 2 2. Ionization chamber and electrometer Ionization chamber model : Serial No. : Type: cyl pp Chamber wall/window material : thickness : g/ 2 Waterproof sleeve/cover material : thickness : g/ 2 Phantom winow material : thickness : g/ 2 Absorbed dose to water calibration factor N D,w = Gy/nC Gy/rdg Ref. conditions for calibration P o : kpa T o : Rel. humidity % Polarizing potential V 1 : V Calibration polarity : +ve -ve corrected for polarity User polarity : +ve -ve Calibration laboratory : Date Electrometer model : Serial No. Calibrated separately form chamber : yes no Range setting If yes, calibration laboratory : Date
3-13. -continued 3. Dosimeter reading and correction for influence quantities Uncorrected dosimeter reading at V 1 and user polarity : nc rdg Corresponding time : min Ratio of dosimeter reading and time : M l = nc/min rdg/min (i) Pressure P : kpa Temperature T : Rel. humidity % (ii) Electrometer calibration factor k elec : nc/dg dimensionless k elec= (iii) Polarity correction rdg at + V 1 : M + = rdg at - V 1 : M + = (iv) Recombination correction (two voltage method) Polarizing voltages : V 1(normal) = V V 1(reduced) = V Readings at each V : M 1 = V M 2= V Voltage ratio V 1/V 2 = Ratio readings M 1/M 2= Corrected dosimeter reading at the voltage V 1 : M = M 1/K TP K elec K pol K s = nc/min rdg/min 4. Absorbed dose rate to water at the reference dopth Z ref D w(z ref) = M N D,W = Gy/min 5. Absorbed dose rate to water at the depth of dose maximum Z max Depth of dose maximum : Z max = 0.5 g/ ) SSD set-up Percentage depth dose at Z ref for a 10 * 10 field size : PDD ( Z ref= g/ ) = % Absorbed dose rate calibration at Z max : D w (Z max ) = 100D w (Z ref )/PDD(Z ref ) = ) SAD set-up TMR at Z ref for a 10 * 10 field size : TMR(Z ref = g/ ) = Absorbed dose rate calibration at Z max : D w(z max) = D w(z ref)/tmr(z ref) = Gy/ min Gy/ min
. (1) Dosimetry ( ) 4.2.1.. 3-1.. cavity.. (Z ref ). ( ) 4.2.3 4.2.4. Co-60 medium. (t win ) 0.2 0.5 cm. (g/cm 2 ). PMMA PMMA = 1.19 g/cm 3 polestylene = 1.06 g/cm 3 PMMA ( polestylene ) x (t win ). 1.0 mm PMMA. gap (0.1 0.3 mm)... (2) ( ) Q TPR 20,10 (Tissue-Phantom Ratio). SCD 100 cm, 10 x 10 cm 20 10 cm. TPR 20,10.
TPR 20,10.. TPR 20,10 SSD 100 cm, 10 x 10 cm PDD. TPR 20,10 = 1.2661 PDD 20,10-0.0595 (3-24) TPR 20,10 SSD 100 cm, 10 x 10 cm 10 cm PDD(10). TPR 20,10 = -0.7898 + 0.0329 PDD(10) - 0.000166 PDD(10) 2 (3-25) ( ) TPR 20,10 3-13 3-14. TPR 20,10, (ratio) /..
3-13.. (Experimental set-up for the determination of the beam quality Q (TPR 20,10 ).)
3-14. (TPR 20,10 ). (Reference conditions for the determination of photon beam quality (TPR 20,10 ).) Influence quantity Phantom material Chamber type Reference value or reference characteristics Water Cylindrical or plane parallel Measurement depth 20 g/ 2 (or 10 g/ 2 ) Reference point of the chamber Position of the reference point of the chamber For cylindrical chambers, on the central axis at the centre of the cavity volume. For plane- parallel chambers, on the inner surface of the window at its centre. For cylindrical and plane-parallel chambers, at the measurement depth. SCD 100 Field size at SCD 10 x 10 3-15.. (Reference conditions for the determination of absorbed dose to water in high energy photon beams.) Influence quantity Phantom material Chamber type Reference value or reference characteristics Water Cylindrical or plane parallel Measurement depth, z ref For TPR 20,10) 0.7, 10 g/ 2 (or 5 g/ 2 ) For TPR 20,10) 0.7, 10 g/ 2 Reference point of the chamber On the central axis at the centre of the cavity volume. Position of the reference point of the chamber At the measurement depth, Z ref SSD/SCD 100 Field size 10 x 10
(3) ( ) 3-15. ( ) 3. Z ref Q. D W,Q = M Q N D,W,Qo k Q,Qo (3-26) k Q,Qo Qo Q M Q. ( ) Z max (Z max ). SSD PDD, SAD TMR. (4) k Q,Qo ( ) Co-60 Qo Co-60 k Q,Qo k Q N D,W,Qo N D,W. k Q Q(, TPR 20,10 ) 3-16. Andero (3.8) 3-15. 0.5 mm PMMA. 1 mm k Q 0.1 %. k Q. k Q 3-14. k Q II. k Q
. Co-60 Q 1.000. Co-60 TPR 20,10 TPR 20,10 Co-60. Co-60 TPR 20,10 0.568 0.579. Co-60., Co-60 TPR 20,10. ( ) N D,W,Qo k Q,Qo. Q k Q,Qo N D,W,Qo k Q,Qo (3-27). N D,W,Qo k Q,Qo. k Q,Qo = (3-27) (5) 3-17.
3-16. TPR 20,10 k Q. (Calculated value of k Q for high energy photon beams for various cylindrical ion chambers as a function of beam quality TPR 20,10.) Ionization chamber type Beam quality TPR 20,10 0.52 0.56 0.62 0.68 0.72 0.76 0.80 0.84 Capintec PR-05P mini 1.004 1.002 1.000 0.996 0.991 0.983 0.968 0.949 Capintec PR-06C/G Farmer 1.001 1.001 0.998 0.992 0.988 0.980 0.965 0.944 Exradin A2 Spokas 1.001 1.001 0.999 0.996 0.992 0.986 0.971 0.949 Far West Tech. IC-18 1.005 1.000 0.993 0.983 0.976 0.966 0.953 0.934 FZH TK 01 1.002 1.000 0.996 0.990 0.984 0.975 0.960 0.939 Nuclear Assoc. 30-750 1.001 1.000 0.998 0.994 0.988 0.979 0.963 0.941 Nuclear Assoc. 30-749 1.001 1.000 0.998 0.994 0.989 0.980 0.964 0.942 Nuclear Assoc. 30-744 1.001 1.000 0.998 0.994 0.989 0.980 0.964 0.942 Nuclear Assoc. 30-716 1.001 1.000 0.998 0.994 0.989 0.980 0.964 0.942 NE 2515 1.001 1.000 0.997 0.991 0.984 0.975 0.959 0.937 NE 2505 Farmer 1.001 1.000 0.997 0.991 0.984 0.975 0.959 0.937 NE 2505/A Farmer 1.005 1.001 0.995 0.985 0.978 0.969 0.955 0.936 PTW 23323 micro 1.003 1.000 0.997 0.990 0.984 0.975 0.960 0.941 PTW 23331 rigid 1.004 1.000 0.997 0.990 0.985 0.978 0.964 0.945 PTW 23332rigid 1.004 1.001 0.997 0.990 0.984 0.976 0.961 0.943 SNC 100730 Farmer 1.004 1.001 0.997 0.990 0.985 0.977 0.963 0.944 Victoreen Radocon 550 1.005 1.001 0.996 0.989 0.983 0.975 0.961 0.943 Victoreen Radocon 555 1.005 1.000 0.995 0.986 0.979 0.970 0.956 0.938 Scdx-Wellhofer IC 05 1.001 1.000 0.998 0.994 0.989 0.980 0.964 0.942 Scdx-Wellhofer IC 15 1.001 1.000 0.998 0.994 0.989 0.980 0.964 0.942 Scdx-Wellhofer IC 25 1.001 1.000 0.998 0.994 0.989 0.980 0.964 0.942
3-14. k Q. (Sigmoidal fits of calculated values of k Q for various ion chambers commonly used for reference dosimetry, as a function of photon beam qualities, Q (TPR 20,10 ).)
3-17.. (Determination of the absorbed dose to water in a high energy photon beam.) Determination of the absorbed dose to water in a high energy photon beam user Date 1. Radiation treatment unit and reference conditions for D w,q determination Accelerator : Nominal Acc. potential : MV Nominal dose rate : MU/min Beam quality, Q (TPR 20,10 ) : Reference phantom : water Set-up : SSD SAD Reference field size : 10 x 10 ( x ) Reference distance : Reference depth z ref : g/ 2 2. Ionization chamber and electrometer Ionization chamber model : Serial No. : Type: cyl pp Chamber wall/window matrial : thickness : g/ 2 Waterproof sleeve/cover matrial : thickness : g/ 2 Phantom winow matrial : thickness : g/ 2 Absorbed dose to water C. F. N D,w = Gy/nC Gy/rdg Ref. conditions for calibration P o : kpa T o : Rel. humidity % Polarizing potential V 1 : V Calibration polarity : +ve -ve corrected for polarity User polarity : +ve -ve Calibration laboratory : Electrometer model : Calibrated separately form chamber : yes no If yes, calibration laboratory : Date Serial No. Range setting Date
3-17. -Continued 3. Dosimeter reading and correction for influence quantities Uncorrected dosimeter reading at V 1 and user polarity : Corresponding accelerator monitor units : Ratio of dosimeter reading and monitor units: M 1 = nc rdg nc/mu rdg/mu (i) Pressure P : kpa Temperature T : Rel. humidity % (ii) Electrometer calibration factor k elec : nc/dg dimensionless k elec= (iii) Polarity correction rdg at + V 1 : M + = rdg at - V 1 : M + = (iv) Recombination correction (two voltage method) Polarizing voltages : V 1(normal) = V V 1(reduced) = V Readings at each V : M 1 = V M 2= V Voltage ratio V 1 /V 2 = Ratio readings M 1 /M 2 = Use IAEA-277, Table 4 for a beam of type: pulsed pulsed-scanned a o= a 1= a 2= Corrected dosimeter reading at the voltage V 1 : M = M 1/K TP K elec K pol K s = nc/mu rdg/mu MU 4. Absorbed dose to water at the reference depth Z ref Beam quality correction factor for the user quality Q:K Q,Q0= taken from Table 9(IAEA-277) Other, specify : D w,q (Z ref ) = M Q N D,W,Qo K Q,Qo = Gy/MU 5. Absorbed dose to water at the depth of dose maximum Z max Depth of dose maximum : Z max = (i) SSD set-up Percentage depth dose at Z ref for a 10 x 10 field size : PDD (Z ref = g/ ) = % Absorbed dose calibration of monitor at Z max : D w,q(z max) = 100D w,q(z ref)/pdd(z ref) = (ii)sad set-up TMR at Z ref for a 10 x 10 field size : TMR (Z ref = g/ ) = Absorbed dose rate calibration at Z max : D w,q (Z max ) = D w,q (Z ref )/TMR(Z ref ) = g/ Gy/ min Gy/MU
. N k N D,W IAEA 277 N k N D,air IAEA 398 N D,W.. Co-60, N k. (cavity air) N D,W. k air Co-60. = N k (1-g) k att k m k cel (3-28) g, k att k m IAEA 277. k cel Co-60 N k electrode. N k Co-60 k air M. N D,air M. N D,air = N k (1-g) k att k m k cel (3-29) N D air". N D = k air (1-g) k att k m k cel (3-30) k cel IAEA. N D cavity. 1 mm electrode (NE-2571)
N D,air IAEA 277 1.006 Co-60. Co-60 N D,air Q N D,air Q. = M Q N D,air (3-31) D W.Q Gragg-Gray. D W,Q (P eff ) = M Q N D,air (S W,air ) Q P Q (3-32) M Q Q S W,air /, P Q Q P eff. P dis D W,Q (P eff ) = M Q N D,air (S W,air ) Q P Q (3-33) P Q = [P cav P dis P wall P cel ] Q (3-34) IAEA 398 IAEA 277. 3-15.
Co-60 k air 3-16. 1 %. N k ( k M, P wall ). 3-15.. ((a) In IAEA TRS-277 the effective point of measurement of a cylindrical ion chamber is positioned at the reference depth Z ref where the absorbed dose is required. (b) Except in electron and heavy ion beams, in IAEA TRS-398 the center of a cylindrical chamber is cositioned at the reference depth Z ref and the absorbed dose is determined at this point.)
3-16. Ka N D,w Co-60. (The ratio of absorbed dose to water in Co-60 determined with calibration factors in terms of absorbed dose to water, N D,w and with calibration factors in terms of air kerma, N K.)
. k Q,Qo (1) k Q,Qo (3-35).. Bragg-Gray k Q,Qo (3-36). k Q,Qo = (3-35) k Q,Qo = (3-36) ICRU 37 (3.9). ICRU 49 (3.10). (W air /e) 33.97 J/C.., Monte Carlo 1. Co-60 S w,air, W air P k Q,Qo. (2) Co-60 Qo k Q. ( ) Co-60 S w,air Co-60 S w,air = 1.133 Andreo. (I value) 0.5 % Co-60 0.1 %.
( ) Co-60 W air W air W air /e. Dry air Co-60 W air /e 33.97 J/C Niatel (3.11) 0.2 %. ( ) Co-60 P Q (Perturbation factor) Bragg-Gray. P i 1. P Q P Q = [P cav P dis P wall P cel ] Q (3-37) P dis P cel. Co-60 P cav P cav medium( ). Z ref ( 5 g/cm 2 ) Co-60 P cav 1.( 0.1 %) Co-60 P dis Z ref Z ref. Johansson (3.12). P dis = 1-0.004 r cyl (3-38) r cyl mm. P dis 0.3 %. Z ref 0.2 %.
Co-60 P wall P wall medium.. P wall. (3-39) 0.5 mm PMMA. S med,air Andreo, Cunningham.. (t w ) = 1 - e -11.88tw (3-40) (t s ) = e -11.88ts (1 - e -11.88ts ) (3-41) t w t s (g/cm 2 ). Andreo P wall 0.5 %. Co-60 P cel P cel electrode. electrode Farmer 1mm electrode Co-60 0.7 %. 1 mm electrode P cel 0.993. 0.2 %.
( ) Co-60 3-18 P dis, P wall, P cel S w,air P Q 3-19. 3-18. P dis, P wall, P cel S w,air P Q. (Values for the factors P dis, P wall and P cel and for the Product S w,air P Q in Co-60 gamma radiation for various cylindrical ionization chamber.) Ionization chamber type P dis P wall P cel S w,air P Q Capintec PR-05P mini 0.992 0.997 1.000 1.098 Capintec PR-06C/G Farmer 0.987 0.989 1.000 1.107 Exradin A2 Spokas 0.981 0.978 1.000 1.088 Exradin A1 mini Shonka 0.992 0.978 1.000 1.100 Far West Tech IC-18 0.991 1.016 1.000 1.141 FZH TK 01 0.986 0.996 1.000 1.113 Nuclear Assoc. 30-750 0.992 0.986 1.000 1.109 Nuclear Assoc. 30-749 0.988 0.986 1.000 1.104 Nuclear Assoc.30-744 0.988 0.986 1.000 1.104 Nuclear Assoc.30-716 0.988 0.986 1.000 1.104 NE 2515 0.988 1.000 0.993 1.112 NE 2505 Famer 0.988 1.000 0.993 1.112 NE 2505/A Famer 0.988 1.012 0.993 1.126 NE 2571 Famer 0.987 0.992 0.993 1.102 PTW 23323 micro 0.993 1.001 0.993 1.119 PTW 23331 rigid 0.984 1.001 0.993 1.109 PTW 23332 rigid 0.990 1.001 0.993 1.115 PTW 30001 Farmer 0.988 1.001 0.993 1.113 SNC 100730 Farmer 0.986 1.001 0.993 1.111 Victoreen Radocon 550 0.990 0.993 1.000 1.115 Victoreen Radocon 555 0.990 1.010 1.000 1.134 Victoreen 30-351 0.988 1.001 1.000 1.121 Scdx-Wellhofer IC 05 0.998 0.986 1.000 1.104 Scdx-Wellhofer IC 15 0.988 0.986 1.000 1.104 Scdx-Wellhofer IC 25 0.988 0.986 1.000 1.104
3-19. Co-60 (3-39). (Estimated relative standard uncertainties of the parameters entering into the denominator of Eq.(3-39) at the Co-60 beam quality.) Component Cylindrical, u c (%) Chamber Type Plane-parallel, u c (%) S w,air Assignment of S w,air to beam quality W air/e P cav P dis P wall P cel 0.5 0.1 0.2 0.1 0.3 0.5 0.2 0.5 0.1 0.2 0.1 0.2 1.5 - Combined standard uncertainty 0.8 1.6 (3) Co-60 (3-39). Co-60 k Q. ( ) S w,air Spencer-Attix S w,air Andreo. Co-60 S w,air Co-60 I 0.5 %. 0.3 %. ( ) W air W air Co-60. 1 %.
0.5 %. ( ) P Q.. P cav % ). Co-60 P cav 1. ( 0.1 P dis k Q. Johansson 0.3 %. MV. Co-60 k Q 0.4 %. P wall Co-60 (3-39). Co-60 P wall 0.5 %. P cel. Co-60. Co-60 0.1 % ( ) 3-20 k Q 1.0 %.
3-20. k Q. (Estimated relative standard uncertainties of the calculated values for k Q for high energy photon beams.) Component u c (%) S w,air relative to Co-60 Assignment of S w,air to beam quality W air/e relative to Co-60 P cav in Co-60 and in high energy photons P dis relative to Co-60 P wall relative to Co-60 P cel relative to Co-60 0.5 0.2 0.3 0.1 0.4 0.5 0.1 Combined standard uncertainty in k Q 1.0
3.. (1) 4 25 MeV.. (variance reduction technique) (megavoltage) (3.13-3.17) (3.18-3.20). MCNP(Monte Carlo N-Particle). (3.19). MCNPX 6 MV Siemens MX2 10 MV Varian Clinac 2100C.. (2) - MCNPX. 6 MV Siemens MX2 10 MV Varian Clinac 2100C 3-17,,,,,. BEAM (3.18)
(cascade).,,, (phase space file).. 0.15 cm. PDD. Siemens MX2 6.7 MeV 0.25 MeV FWHM, Varian Clinac 2100C 11 MeV. 50 50 30 cm 3. (PDD: percentage depth dose) 4 4 0.5 cm 3, 10 cm 0.5 2 2 cm 3. *F8 (cut-off) 0.01 MeV 0.1 MeV. EPDL(Livermore Evaluated Photon Data Library) (3.22) 1keV 100 GeV MCPLIB02. ETRAN(Electron TRANsport) (3.23) Integrated Tiger Series(ITSv3.0) (3.24) 1keV 1GeV EL03. 3.0 GHz MS-Windows. (Scanditronix Wellh fer Blue Phantom). 5.8 mm, 6 mm (Scanditronix Wellh fer CC13).
(a) (b) 3-17. Linac head. (Schematic diagram of linac head. (a) 6 MV Siemens MX2 (b) 10 MV Varian Clinac 2100C.) (3) ( ) 100 cm 3cm 3-18. 3-18 1, (bin) 0.1 MeV. 3%. (energy weighted mean energy) Siemens MX2 Varian Clinac 2100C 1.93 MeV 2.97 MeV. 1/3 (3.25).
3-18.. (Calculated photon energy spectra. (a) The 6 MV beam from the Siemens MX2; (b) The 10 MV beam from the Varian Clinac 2100C.)
( ) (PDD). PDD 3-19. 100%. (SSD: Source Surface Distance). 1%. 3-19 MCNPX PDD ±2%, 15%. (buildup region) (3.26). PDD 3-21, 10 MV BJR suppl. 25 (3.27). 3-21.. (Comparison of some of the beam quality parameters. The PDDs of the 6 MV and 10 MV beam were obtained for a 99 cm 2 field at 90 cm SSD and a 10 10 cm 2 field at 100 cm SSD respectively. D 10, d 80 and d m are a PDD at 10 cm depth, a depth of an 80% dose and a depth of a peak dose, respectively.) Parameter 6 MV Siemens MX2 10 MV Varian Clinac 2100C Calculation Measurement Calculation Measurement BJR suppl. 25 D 10 (%) 65.8 65.9 73.4 74.0 73.0 d 80 (cm) 6.3 6.3 8.2 8.3 8.0 d m (cm) 1.5 1.5 2.5 2.3 2.3
3-19.. (Comparison of the calculated and measured depth dose curves. (a) The 6 MV beam from the Siemens MX2; (b) The 10 MV beam from the Varian Clinac 2100C.)
( ) 3-20 10 cm. 1. 5cm 1%. 3-20 100% 50% ±2%, (20% 10% ) 7%. (spatial resolution),. 3-20 80% 20% 1mm. (4) MCNPX 6 MV Siemens MX2 10 MV Varian Clinac 2100C, PDD. PDD MCNPX.., MCNPX.
3-20.. (Comparison of the calculated and measured cross profiles. (a) The 6 MV beam from the Siemens MX2; (b) The 10 MV beam from the Varian Clinac 2100C.)
. TLD / (KCCH). Co-60 (N K ), (Absorbed dose to air factor (N D,air )). IAEA-277,. N K 1.5 %. N K. (1) (N D,air ) N D,air. ( ) ( ) Chamber model and serial number : PTW N30006, No. 192 Cavity inner radius : 3.05 mm Wall material : PMMA thickness : 0.045 g/ Buildup cap material : PMMA thickness : 0.541 g/ total thickness : 0.586 g/ ( ) Calibration laboratory data Calibration laboratory and date : A Calibration factor (kerma in air), N k = 48.950 10-3 Gy/scale div ( : 1.1 %)
given at P O = 101.3 kpa, T O = 22 and 50 R.H. Polarizing voltage : -400 V, field size : 10 10 Source chamber distance : 100 ( ) Constants k att k m = 0.973 W/e = 33.97 J/C 1-g = 0.997 (for 60 Co gamma radiation). k m : k att : (B.C. ) ( ) Absorbed dose to air calibration factor D air,u = K air,c (1-g)k att k m : IC N D,air = N k (1-g)k att k m P T,P : = 4.746 x 10-2 obtained at 101.3 kpa, 22, 50 R.H Polarizing voltage : -400 V, field size : 10 10 (2). Co-60 3-22. ( ) Dw Radiation treatment unit : Theratron 780, 60 Co : 5 cm : 0.6 r Field size : 10 10 at SSD = 80 cm ( ) Chamber model and serial number : PTW N30006, No. 192
Wall material : PMMA thickness : 0.045 g/ Electrometer model : PTW UNIDOS 10005, No. 50114 Absorbed dose to air chamber factor : N D = 47.468 10-3 Gy/div at P O = 101.3 kpa, T O = 22, 50 R.H. Polarizing voltage : 400 V ( ) Electrometer Reading Mu = 5.00(div/min) Pressure, P = 100.7 kpa Temperature, T = 24.7 Po = P Humidity correction k h = 1.000 Recombination correction (IAEA-277 Table or, or Fig.13) V 1 = 250 V, V 2 = 83.3 V, M 1 /M 2 =1.001, p s = 1.000 P TP (273.2 + T) = 1.005 (273.2 + T ) o ( ) Stopping power ratio water/air (IAEA-277 Table ), S w,air = 1.133 Perturbation factor, P qall = 1.001 Central electrode correction P cel = 1.000 D ( P ) = M N s, p 0.2690 Gy w eff u D w air u = / min D w ( Zmax) = 0.3413 Gy / min
3-22.. (Water absorbed dose with the photon energies) Energy SSD Dw(Zref) Dw(Zmax) Co-60 80 0.2690 Gy/min at 5cm 0.3413 Gy/min 6 MV 100 0.872 Gy/100 mu at 5cm 1.003 Gy/100 mu 10 MV 100 0.731 Gy/100 mu at 10cm 1.001 Gy/100 mu 15 MV 100 0.772 Gy/100 mu at 10cm 1.004 Gy/100 mu. TLD (1) TLD ( 20 MeV ) ( ) TLD KLT-300(LiF:Mg,Cu,Na,Si, Korea), GR-200((LiF:Mg,Cu,P, China) MCP-N((LiF:Mg,Cu,P, Poland) 3 TL 1.25 MeV(Co-60) 21 MV (Microtron). IAEA/WHO TL (element correction factor (ECF)) TL. ECF TL. Co-60 20 MV. ( ) KLT-300 2 GR-200 MCP-N GR-200 0.8 mm, MCP-N
0.9 mm. TLD ECF Cs-137. TL Co-60, 6 MV, 10 MV 21 MV, 3-23.. IAEA (30 x 30 x 30 cm) TL. Perspex Co-60 6 MV 10 x 10 x 10 cm, 10 MV and 21 MV 10 x 10 x 20 cm.. TLD. 3-23. TLD. (Radiation field characteristics to be used in the energy response experiments of the TL pellets.) Radiation Energy Radiation source TPR 20-10 S w,air Phantom Used Co-60 60 Co Teletherapy Unit T780(AECL, Canada) 1.133 30x30x30 Water 10x10x10 PMMA 6 MV Linac, Mevatron (Siemens, USA) 0.679 1.119 30x30x30 Water 10x10x10 PMMA 10 MV Microtron, MM22 (Scanditronix, Sweden) 0.737 1.105 30x30x30 Water 10x10x20 PMMA 21 MV Microtron, MM22 (Scanditronix, Sweden) 0.782 1.090 30x30x30 Water 10x10x20 PMMA TLD source-surface distance(ssd) = 1 m, 2 Gy Z ref Co-60, 6 MV 10 MV 5 cm, 21 MV 10 cm. TLD glow curves N 2 10 /sec TLD (Harshaw Model 4500).
3-21. 3-21.. (Experimental set-up for energy reponses of the TLDs.) ( ) (effective point of measurement) D W,Q (P eff ) IAEA-277. D W,Q (P eff ) = MN k (1-g)k att k m (S W,air ) Q P Q (3-42) M PTW 30006, N k Co-60 air kerma, (S W,air ) Q Q. IAEA-277. PTW 30006 Co-60 N k N k = 4.895 x 10-2 Gy/nC, 3-24. KLT-300 Co-60 3-25, TLD Co-60 3-26. 3-22. 2 Gy. 3-25 3-26 3-22 KLT-300 Co-60 6%