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2 Radiochromic Film 을이용한저선량피폭측정용 Brain Phantom 개발 : : :

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6 S U M M A R Y. Title: Development of Brain Phantom for Radiochromic Film Dosimetry at Low-dose Exposure. Purpose of Research To establish a film dosimetry system for photon source beam and to develop a new form of brain phantom for measuring the dose dispersion of micron-sized beam in target volumes.. Contents of Research 1. To establish a dosimetry system utilizing radiochromic films - To write a program for quantitating the optical density of films at radiation exposure - To specify the dose range of film measurement with reliability 2. To characterize the tissue equivalency of candidate phantom materials - To compare the photon energy absorption by human brain matter and candidate materials - To compare the photon energy slowing down by human skull and candidate materials 3. To design the brain phantom - To suggest phantom structure that enables film holding - To arrange film positioning for micron-scale spatial resolution of dose measurement 4. To complete a model brain phantom composition - To assemble a brain phantom - To demonstrate dose estimation in the brain phantom

7 . Results of Research - A film dsimetry system has been established for photon beam. - A brain phantom has been assembled for measurement of dose dispersion under the exposure to micron-sized beam. - The radiochromic film dosimetry system and the brain phantom have been utilized to measure the dose profile in brain under the exposure to the micron-sized beam. Inside the brain phantom, micron-sized dose profile was maintained with minor dose dispersion.. Application of Results - The radiochromic film dosimetry system enables one to measure doses in micron-scale resolution. - The brain phantom can be utilized for measuring dose distribution in the brain matter under X-ray exposure, in micron-scale spatial resolution by holding radiochromic films inside. - If future research work provides clear explanation of the effectiveness of discrete micron-sized beam arrangement in radiation treatment, it would bring the economic impact on the medical industry as well as on the radiation industry.

8 CONTENTS SUMMARY (Korean) SUMMARY (English) CONTENTS (English) CONTENET (Korean) Chapter 1. Introduction Chapter 2. Technical Status at Home and Abroad Chapter 3. Research Scope and Results Chapter 4. Achievement and Contribution Chapter 5. Applications of Results Chapter 6. Data Collection Chapter 7. References

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10 ,., 10 discrete micron-sized beam, brain tumor,. rat mouse in vivo animal,,. discrete micron-sized external beam micron scale discrete dose, discrete micron-sized external beam therapy. brain phantom, phantom x-ray phantom. phantom, phantom ( 10000$ )., discrete micron-sized external beam therapy brain phantom, phantom low tube-current hard (up to 450 kev) x-ray beam.

11 3. Radiation sensor radiochromic film dosimetry. X-ray beam brain. phantom, phantom head., skull brain matter skull-equivalent brain matter-equivalent brain matter phantom.

12 2. 1. brain phantom, phantom., head phantom body hantom. 2. / - head (2003). - brain tumor Gafchromic film dosimetry - water x-ray (2007). - - phantom (2008) MeV photon beam,. Japan Kyoto Kagaku Co. - Therapy Body Phantom THRA1 (standard Japanese man's head phantom consisting of soft tissue and bone tissue). - ( : dosimetry for Leksell Gamma Knife therapy) USA CIRS - brain, bone spinal cord, vertebral disks, soft tissue head phantom. - ( : head 3D dose distribution )

13 3., % 3%.,. discrete micron-sized beam,. brain phantom, head phantom head photon equivalency., phantom, equivalency., phantom ( ),.

14 x-ray dosimetry phantom. water phantom dosimeter, water phantom phantom water phantom solid phantom. solid phantom dosimeter,,. solid phantom,. solid phantom.. 1MeV photon, photon beam phantom kev photon phantom. photon photon phantom. Radiochromic film kilovoltage photon dosimetry brain phantom.. MCNP5 brain phantom

15 . PMMA, polystyrene, RW3, PMMA polystyrene(clear polystyrene) phantom, RW3 white polystyrene polystyrene TiO 2 2wt% effective atomic number. white polystyrene Gunter Christ (1995) high energy photon. 2. Phantom photon. photon. 5 : Rayleigh scattering, photoelectric absorption, Compton scattering, pair production, photonuclear interation. Photoelectric absorption, Compton scattering, pair production photon. Rayleigh scattering photon photon. Photonuclear interaction photon MeV. Photon photon beam (Z). 1 photon photoelectric absorption, Compton scattering, pair production.. photon photoeletric effect, pair production. photon Compton scattering, MeV photon pair production. (carbon, air, water, human tissue ) Compton scatterign.

16 1. 3 photon interaction mode photon energy Z value (Attix 1986). 2 photon water mass attenuation coefficient photon. photon 100 kev photoelectric effect compton effect, 100 kev compton effect. pair production threshold energy 1.02 MeV compton effect pair production, MeV pair production. 2. Photon water mass attenuation coefficient photoelectric absorption, Comton scattering, pair production attenuation (Attix 1986).

17 3 x-ray x-ray energy. x-ray beam bremsstrahlung., 150 kv, 20 kev 150 kev photon photon 60.7 kev. 60 kev photon x-ray. x-ray 450k V, x-ray photon 20 kev 450 kev. 3. x-ray (YXLON D-408) Bremsstrahlung x-ray energy spectrum., beam photoelectric effect compton effect

18 . bremsstrahlung x-ray energy 100keV photon photoelectric effect. x-ray (YXLON D-408) photoelectric effect compton effect. 3. Photon attenuation coefficient Attenuation coefficient photon attenuation coefficient. Mass attenuation coefficient. μ ρ τ ρ σ ρ κ ρ (cm2 /g) μ ρ = total mass attenuation coefficient (cm2 /g); τ ρ = photoelectric mass attenuation coefficient (cm 2 /g); σ ρ = compton mass attenuation coefficient (cm2 /g); τ ρ = pairproduction mass attenuation coefficient (cm 2 /g). Total mass attenuation coefficient photoelectric absorption, Compton scattering, pair production mass attenuation coefficient., 450 kev photon beam pair production pair production. μ ρ τ ρ σ ρ (cm2 /g). Compton scattering, photon electron unbound stationary., high Z low ν electron binding effect compton effect photoelectric effect., binding effect., Compton mass

19 attenuation coefficient. σ ρ σ (cm 2 /g) σ = Compton-effect cross section per electron (cm 2 /electron); = Avogadro's constant; = number of electrons per atom of an element or per molecule of a compound; = number of grams per mole of material; ρ = density in g/cm 3 ; = number of electrons per gram of material. Z/A 1 hydrogen, Z/A %, 0.5. Compton linear attenuation coefficient. σ ρ σ (cm -1 ) σ ρ ρ compton effect linear attenuation coefficient. photoelectric attenuation coefficient, The interaction cross section per atom for photoelectric effect. τ ν (cm2 /g) = constant; 4 at ν = 0.1 MeV, gradually rising to about 4.6 at 3 MeV; m 3 at ν = 0.1 MeV, gradually decreasing to about 1 at 5 MeV. ν 0.1 MeV

20 photoelectric absorption. Photoelectric mass attenuation coefficient. τ ρ ν = constant; = Avogadro's constant; = the number of electrons per atom of an element or per molecule of a compound; = the number of grams per mole of material; ρ= density in g/cm 3., photoelectric effect linear attenuation coefficient. τ ρ where 3<m<4 Photon ( ν), photoelectric mass attenuation coefficient Z/A, ρ, Z atomic number(z)., attenuation coefficient, attenuation coefficient Z/A, ρ, Z. 4. Z/A, Z eff Phantom Z/A Z. Z/A Z Bragg additivity the mean ratio <Z/A,> effective atomic number.. = the fractional elemental composition for the ith element with atomic to mass

21 number ratio. effective atomic number Σ, photoelectric effect photoelectric effective atomic number. phantom photoelectric effective atomic number Bragg additivity. τ ρ (3<m<4) α where α, 3<m<4 Z photoelectric absorption. tissue attenuation m 2.94 (Walter 1926; Mayneord 1937; Spiers 1946) 3.1 (Hine 1952). Weber Van den Berge (1969) 3.4, Cho, Tsai Wilson(1975). Johns Cunningham (1983) m = 3.5. m 3.5 photoelectric atomic number. α <Z/A>,,,, photoelectric-effective atomic number 1. 1 PMMA, polystyrene, RW3 photoelectric effective atomic number

22 . RW3 Polystyrene, PMMA. photoelectric effect RW3 ρ RW3. Compton effect.

23 Table 1. Mean ratio of atomic number to atomic mass <Z/A>, physical density, photoelectric-effective atomic number, electron number density, effective photoelectric absorption cross section for different bone-equivalent materials. Material Composition in Z (fraction by weight) Mean Ratio <Z/A> Density (g/cm 3 ) *Effective Z ρ ρ brain (ICRP) 1 (0.110) 6 (0.125) 7 (0.013) 8 (0.737) 11 (0.0018) 12 ( ) 15 ( ) 16 ( ) 17 ( ) 19 (0.0031) 20 ( ) 26 ( ) 30 ( ) water 1 ( ) 8 ( ) RW3 1 ( ) 6 ( ) 8 ( ) 22 ( ) poly -styrene 1 ( ) 6 ( ) PMMA 1 ( ) 6 ( ) 8 ( ) * with m=3.5

24 2. 1. photon energy attenuation/absorption Phantom beam phantom. photon brain matter. solid phantom brain matter., r (phantom Material) brain matter. Phantom bremsstrahlung x-ray beam MCNP5. sphere phantom point source detector. photon source, x-ray generator beam energy source. nps relative error R photon point source, sphere phantom r

25 . Photon 60 kev photoelectric effect photoelectric attenuation coefficient brain matter phantom brain matter. phantom photoelectric attenuation coefficient polystyrene, RW , 450keV photon source water, RW3, PMMA, polystyrene phantom r. Photon 60keV 450keV 1 photon photonelectric absorption Compton effect. source 1, source 450 kev 1%. brain matter photoelectric attenuation coefficient brain matter 1% brain attenuation coefficient. Brain matter 99% attenuation coefficient water.

26 5 x-ray 150, 250, 350, 450 kv x-ray photon point source, sphere phantom r (r). 3 x-ray x-ray bremsstrahlung, 20 kev photon. photon tungsten x-ray photon 60.7 kev. x-ray phantom photoelectric absorption photoelectric attenuation coefficient brain matter phantom, 150 kv 450 kv Compton scattering photon 1. photoelectric absorption photoelectric attenuation coefficient RW3 brain matter, PMMA, polystyrene., energy softening effect sphere phantom r 1., 350 kv x-ray photon, RW3, PMMA, polystyrene 2 cm 1, 6, 8%, 450 kv spectral energy beam, RW3, PMMA, Polystyrene 2 cm 1, 5, 6%.

27 5. x-ray 150, 250, 350, 450kV x-ray, phantom r. ICRU Report 44 solid phantom uncertainty 1%, correction factor (ICRU, 1989). uncertainty 1% x-ray photon uncertainty MCNP5 correction factor phantom. \, x-ray photon 100 kev 1 MeV, correction factor.

28 , x-ray x-ray uncertainty RW3 phantom. RW3 phantom polystyrene PMMA. 2. Bone-equivalent photon energy attenuation Water equivalent material bone equivalent material brain phantom.. Brain phantom skull bone density : bone density = 1.85 g/cm3, 6.40% of hydrogen, 27.80% of carbon, 2.70% of nitrogen, 41.00% of oxygen, 0.20% of magnesium, 7.00% of phosphorus, 0.20% sulphur, and 14.70% calcium by mass (Joel Y.C et al, 2002). Skull photon attenuation coefficient skull density, atomic number, electronic density. Tony Whelan (1994), calcium hydroxyapatite bone, calcium hydroxyapatite. polyethylene Calcium hydroxyapatite, polyhydroxybutyrate calcium hydroxyapatite. Takuya Hirai ultrasonic imaging of the bone, apatite PVA(polyvinyl alcohol) 7:3 bone-mimicking phantom standard bone., Bone equivalent material CHA(Calcium hydroxyapatite). CHA, pycnometry CHA density 3.15g/cm3 (Dragan P. Uskokovic et al, 2007),,,, 0.2%, 41.40%, 18.50%, 39.90% (Agostino Tartari, 1999).

29 polyethylene polyvinyl alcohol CHA. 2. density skull density, CHA polyvinyl alcohol skull., CHA polyvinyl alcohol skull. Table 2. Mean ratio of atomic number to atomic mass <Z/A>, density, photoelectric -effective atomic number for the compounds of polyvinylalcohol+cha and polyethylene+cha. Material Mean Ratio <Z/A> Density (cm 3 /g) *Effective Z skull CHA+PVA (5:5) CHA+Polyethylene(7:3) density element composition CHA PVA total density,, photoelectric effective atomic number., skull density,, photoelectric effective atomic number (Table 3).

30 Table 3. Mean ratio of atomic number to atomic mass <Z/A>, physical density, photoelectric-effective atomic number, electron number density, effective photoelectric absorption cross section for different bone-equivalent materials. Material Skull CHA PVA CHA+PVA (5:5) CHA+PVA (37.5:62.5) CHA+PVA (41:59) Composition (fraction by weight) 1(0.064) 6(0.278) 7(0.027) 8(0.41) 12(0.002) 15(0.07) 16(0.002) 20(0.147) 1(0.002) 8(0.414) 15(0.185) 20(0.399) 1(0.076) 6(0.904) 8(0.008) 22(0.012) 1(0.047) 6(0.273) 8(0.388) 15(0.093) 20(0.199) 1(0.058) 6(0.341) 8(0.382) 15(0.069) 20(0.15) 1(0.0548) 6(0.322) 8(0.384) 15(0.0758) 20(0.164) Mean Ratio <Z/A> Density (cm 3 /g) *Effective Z ρ ρ * when, m=3.5 * ρ ρ ρ

31 CHA PVA, skull density 50 : 50, photoelectric effective atomic number 37.5 : 62.5, photoelectric attenuation coefficient 41 : 59. electron density skull. photoelectric attenuation coefficient skull 41 : 59 skull phantom x-ray x-ray. MCNP5 skull skull photon energy attenuation. sphere water phantom skull skull. skull ( 6, 1998) 7.5 mm. sphere phantom source 150, 250, 350, 450kV x-ray energy, detector. nps relative error (R) , skull phantom skull.

32 6. 150, 250, 350, 450kV x-ray point source r ~ 450kV x-ray energy spectrum photoelectric effect, photoelectric attenuation coefficient skull CHA : PVA = 41 : photoelectric attenuation coefficient skull CHA : PVA = 50 : 50 phantom skull, photoelectric attenuation coefficient skull CHA : PVA = 37.5 : 62.5 phantom skull. 150 kv 450 kv Compton scattering

33 photon, photoelectric effective Z 1., calcium hydroxyapatite powder, calcium hydroxyapatite ceramic (Safronova et al. 2007). CHA PVA 41 : 59 skull. 3. Aluminium skull Head skull brain tissue. Skull skull brain matter intensity skull brain tissue skull. Skull bone phantom aluminium skull. Table 4. Mean ratio of atomic number to atomic mass <Z/A>, physical density, photoelectric-effective atomic number, electron number density, effective photoelectric absorption cross section for skull and aluminium. Material Mean Ratio <Z/A> Density (cm 3 /g) *Effective Z ρ ρ Skull aluminium Aluminium skull, linear attenuation

34 coefficient skull. Compton linear attenuation coefficient ρ aluminium skull 1.327, photoelectric linear attenuation coefficient ρ aluminium skull Compton effect photoelectric effect aluminium linear attenuation coefficient skull aluminium skull linear attenuation radiation intensity. skull 7.4mm 6.mm. skull 7.4mm skull aluminium. X-ray tungsten target x-ray 60 kev bremsstrahlung x-ray. photon skull photoelectric effect bremsstrahlung x-ray Compton effect. Aluminium photoelectric linear attenuation coefficient skull skull 7.4mm 1/ mm aluminium 7.4mm skull photoelectric linear attenuation. Compton effect skull 1/ mm aluminium skull Compton linear attenuation. skull 6.3mm 1/ mm aluminium 6.3mm skull photoelectric linear attenuation. Compton effect skull 1/ mm aluminium skull Compton linear attenuation., skull linear attenuation aluminium ~ 5.576mm, skull linear attenuation aluminium 3.93 ~ 4.75mm.. skull aluminium PMMA head phantom x-ray. Phantom head. bremsstrahlung x-ray spectrum

35 beam source 150kV, 250kV, 350kV, 450kV. Phantom source 50cm ( beam window 30cm ) skull photon PMMA phantom. skull skull aluminium data. skull aluminium skull spectrum. 7 ~ 8 head phantom skull skull aluminium phantom (D aluminium /D skull ). 7, 8 Brain tumor 2cm 1 aluminium Table kV x-ray spectrum 4.8mm aluminium 7.4mm skull, Compton effect 350kV 5mm. Skull 1.5mm 150kV x-ray spectrum 5mm aluminium skull 2% aluminium 5mm. 150kV 4.1mm aluminium 6.3mm skull 250kV 450kV 4.2mm aluminium 6.3mm skull. 0.1mm aluminium 4 mm 1% 4mm.

36 7. 150, 250, 350, 450 kv x-ray spectrum source phantom. ( skull 7.4 mm ).

37 8. 150, 250, 350, 450kV x-ray spectrum source phantom. ( skull 6.3mm ). Table 5. Skull equivalent aluminium thickness. 150kV 250kV 350kV 450kV Thickness ( ) 4.8mm 4.9mm 5mm 5mm Thickness ( ) 4.1mm 4.2mm 4.2mm 4.2mm Skull aluminium photon PMMA phantom x-ray spectrum skull aluminium photon

38 PMMA phantom x-ray energy spectrum. x-ray spectrum intensity, particle detector photon. skull equivalent thickness aluminium skull , 250, 350, 450kV x-ray spectrum source phantom energy spectrum. ( skull 7.4mm ).

39 , 250, 350, 450kV x-ray spectrum source phantom energy spectrum. ( skull 6.3mm ). 4. Head phantom correction factor head phantom correction factor. 11 Table 6 head phantom correction factor, 450kV correction factor 5%. Correction factor aluminium skull PMMA brain matter 10% head phantom. correction factor ICRU Report 44(ICRU, 1989) 1% beam source correction factor MRT(microbeam radiation therapy).

40 11. Head phantom correction factor. (a) (b) Table 6. Skull equivalent aluminium thickness. 150 kv 250 kv 350 kv 450 kv 0 cm cm cm cm cm cm kv 250 kv 350 kv 450 kv 0 cm cm cm cm cm cm

41 5. Brain phantom,.,,., depth dose., x-ray 150 kv bremsstrahlung x-ray circular beam source, beam size 3 cm. 12, 1 mm, 1 cm 3 cm-deep depth dose rate, 2 cm 3 cm-deep depth dose rate., depth dose., 2010 ~mm cm-deep dose rate

42 6. X-ray beam x-ray x-ray, x-ray tube target x-ray 40 o x40 o [2p x (40 o x 40 o )/(180 o x 180 o ) ~ 2p x = 4p x ] beam., collimator phantom x-ray beam., x-ray beam,. MCNP5, 450 kv bremsstrahlung. 13, 1.7 cm 0.1% 5 cm %. 5 cm beam collimator beam collimator. phantom kv bremsstrahlung x-ray,

43 7. Radiochromic film micron beam Ferreira (2009), radiochromic film EPSON scanner 50, 75, 150, 300 dpi 4 75 dpi (optical density)., EPSON 1000XL scanner 75 dpi x-ray beam EBT radiochromic film EBT. 75 dpi 1 inch (2.54cm) 75 pixel, 75, 2.54 cm/75 = 339 mm resolution 339 mm x 339 mm. film scanning resolution, 300 dpi 85 mm x 85 mm resolution. Matlab pixel, 14 optical density. pixel optical density dose vs. optical density standard curve dose. 15 radiochromic film EBT standard curve (Lee et al. 2010), Table 7 15 standard curve film optical density dose. 14. x-ray beam 0.16 x 0.16 inch 2 film dose vs. optical density in 12 x 12 pixels.

44 15. Standard curves in terms of optical density (OD) versus dose for the response of Gafchromic EBT film to radiation exposure at doses ranging from 25 cgy to 300 cgy (Lee et al., 2010). Table 7. x-ray beam Gafchromic EBT film optical density digital image date dose ( : Gy)

45 8. Head phantom, Collimator & sliding plate phantom Head phantom. head phantom 16 head phantom skull aluminium brain matter PMMA. skull 4mm 1mm aluminium, brain matter 2, 3, 5mm PMMA film. 16. Head phantom 17 collimator sliding plate. Collimator x-ray, servo motor 100 mm collimator. x-ray servo motor microbeam micrometer system.

46 17. Collimator and sliding plate. 9. Radiochromic film dosimeter head phantom collimator penumbra Microbeam tungsten collimator radiochromic film head phantom microbeam 18. Collimator 2mm, 150 kv x-ray. 720dpi film pixel 35 mm 18 FWHM(Full width at half maximum) 2.6 pixel. microbeam FWHM 90 mm.

47 18. Radiochromic film dosimeter FWHM(Full width at half maximum) 90 mm 150 kv microbeam. 19, mm sliding plate FWHM 90 mm 150 kv microbeam 300, 500 mm head phantom radiochromic film. microbeam, microbeam peak valley. 19. Sliding plate 300 mm 150 kv microbeam.

48 20. Sliding plate 500 mm 150 kv microbeam. 10. Radiochromic film dosimetry head phantom micron-sized beam dose dispersion Radiochromic film dosimetry head phantom microbeam head brain dose dispersion. 21 FWHM 130 mm 150 kv microbeam skull head phantom phantom dose dispersion. 4mm aluminium, PMMA 0.5, 1, 2, 3cm radiochromic film x10 cm broad beam FWHM 130 mm microbeam head phantom. microbeam braod beam. broad beam microbeam. 21 phantom FWHM.

49 kv microbeam head phantom dose dispersion Broadbeam microbeam Relative depth dose Distance (cm) x 10 cm broad beam FWHM 130 mm 150 kv microbeam head phantom phantom.

50 23 50, 100, 125, 150, 200, 400 kev X-ray, 25 mm, 175 mm, 5 mm collimator water phantom dose Monte carlo code MCNP5. 6 mm skull-equivalent material dose dispersion. 150 kv microbeam phantom dose dispersion ( kv ) film ( 22), 150 kv X-ray beam, phantom dose dispersion., dose dispersion beam discretization phantom phantom.

51 23. 50, 100, 125, 150, 200, 400 kev X-ray, 25 mm, 75 mm, 5 mm collimator phantom dose dispersion.

52 4. 1. (%) radiochromic film dosimetry. 50 % - film dosimetry - dose brain tissue-equivalent composition. 50 % - composition - brain tissue-equivalency brain phantom. 50 % brain tissue-equivalent phantom. 50 % - phantom - - phantom - phantom radiochromic film dosimetry. brain tissue-equivalent phantom. 25 % - film dosimetry % - phantom brain phantom, head phantom head photon equivalency., phantom, equivalency

53 . phantom ( ) phantom.

54 5. -,., 10 discrete micron-sized beam, brain tumor,. discrete micron-sized external beam micron scale discrete dose, discrete micron-sized external beam therapy. - 3-D conformal radiation therapy, stereotactic radiation surgery, intensity-modulated radiation therapy (IMRT), image-guided radiation therapy (IGRT)., continuous mm-scale phantom film dosimetry. brain phantom film dosimetry, discrete micron-sized beam discrete micron-sized beam therapy paradigm. -, discrete micron-sized beam, discrete micron-sized beam protocol discrete multiple micron-sized beam,.

55 Film dosimetry - Gafchromic film dosimetry 1997 Klassen lucite phantom 60 Co gamma-ray. Gafchromic MD-55 film 6 Gy, 1% uncertainty. - International Speciality Products Gafchromic EBT radiochromic film, film coloration, coloration optical density MD-55-2 (13%), XR type T (15%) and HS (19%) radiochromic film 6% ~ 9%., 6 coloration optical density 1% (Cheung et al., 2005). Post coloration GAMMEX solid water phantom. - External beam sensor Gafchromic EBT film 2006 Todorovi. Gafchromic EBT prototype B Kodak EDR2 film 0.1 ~ 8 Gy Gafchromic EBT film 10 Kodak EDR2 film field size EBT film. Euromechanics solid water phantom. - Radiochomic film, film optical density. Hupe Brunzendorf film dosimetry color scanner (2006), film dosimetry. RGB (Red, Green and Blue) format digital scanning image color channel film (calibration curve) color scanner

56 . radiochromic film HS, MD55-2 EBT type film scanner. - cyberknife cyberknife film dosimetry, Wilcox and Dasalov Accuracy cyberknife 5 ~ 60 mm solid water phantom EBT Gafchromic film ion chamber (2007). lateral elctronic disequilibrium high-resolution dosimeter., near tissue-equivalency, high spatial resolution self developing EBT film. - Sankar, VXR-16 film scanner EBT Gafchromic film dosimetry 0~600 cgy EBT film linear response (2008)., post-irradiation color growth, film, scanner film density. 2. Head phantom - CIRS radiosurgery head phantom ( 23) brain, bone spinal cord, vertebral disks, soft tissue "x2.5"x2.5" film cassette film, gel, TLD holder head dose 3. CT therapy 50 kev ~ 25 MeV 1%.

57 23. CIRS model 605 brain phantom - Gafchromic films MD-55-2 film dosimeter Leksell gamma knife therapy. Yamauchi Kyoto Kagaku Co., Ltd. standard japanese man's head phantom ( 24) gamma knife 4 mm, 8 mm, 14 mm 18 mm collimator head. 4 mm, 8 mm 14 mm collimator Leksell gamma knife plan dose, 18 mm collimator, plan dose 5%. 24. standard japanese man's head phantom MD-55-2 film dosimetry.

58 -, (stereotactic radiation treatment) head brain phantom Gafchromic film head ( 2003). brain phantom ( 25) 8 cm head. 10 cm, ionization chamber film. phantom, ionization chamber. ionization chamber. 25. phantom (2003). - solid water-equivalent phantom, 10 MV X-ray phantom ( 26). 26. body phantom LINAC x-ray beam.

59 - water, head phantom 5% ( 2007) ( 27). 27. head phantom (2007) Radiochromic films - Gafchromic EBT film Gafchromic EBT2 film. EBT2 film EBT film. (1) dose range film 1cGy - 8Gy 1cGy - 10 Gy (red color channel ), green color channel 40cGy. (2) film energy dependency <10% film response different from 60 kev into the MV range (3) (blue yellow), density. 2. Brain or head phantom - PTW cylindrical (20 cm-diameter and 22 cm-height) PMMA phantom ( 28) ion chamber.

60 28. PTW cylindrical PMMA phantom - PTW, ion chamber film cylindrical sliced RW3 phantom ( 29) radiochromic film IMRT beam. 29. PTW cylindrical PMMA phantom

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64 자체평가의견서 1. 과제현황 과제코드 부처사업명 ( 대 ) 사업명 ( 중 ) 원자력연구개발사업 원자력기반확충사업 세부사업명 ( 소 ) 미래연구 ( 핵심기초 ) 부처기술분류공학원자력공학 국가과학기술표준분류체계 원자력 방사선기술 (N07) 방사선방어, 이용및방사성폐기물 (G30606) 방사선계측 / 선량평가기술 (N0705) 국가기술지도 (NTRM) B 총괄과제총괄책임자 ( 기관 ) 과제명 Radiochromic Film 을이용한저선량피폭측정 Brain Phantom 개발 연구단계 최종 연구기관서울대학교연구책임자김은희 연차기간정부민간계 연구기간 연구비 ( 천원 ) 1차연도 ,000 50,000 2차연도 ,000 50,000 3차연도 4차연도 5차연도 계 100, ,000 참여기업상대국상대국연구기관비고 : 총괄과제란은총괄과제에해당하는경우에만기재합니다. 2. 평가일 : 평가자소속 직위 성명 서명 서울대학교 김은희 4. 평가자확인 본인은평가대상과제의연구결과에대하여객관적으로기술하였으며, 공정하 게평가하였음을확약하며, 이자료가전문가및전문기관평가시에기초자료 로활용되기를바랍니다. 확약

65 Ⅰ. 연구개발실적 1. 연구개발결과의우수성및창의성 - 본연구는 phantom 제작에서사실적모사에집착하는고정관념을떠나, 불필요한다수의요건을제거하고실험자또는실험의도에부합하는필수적인요소에한해 equivalency를확보한다는개념에기반하여수행되었음. 이러한상황하에서는실험자가구조와재료면에서 phantom을재구성하기가용이하므로 ( 확보가용이한재료이용과국내업체에제작의뢰 ) phantom이보다다양한방법으로이용될수있을것으로기대함. 2. 연구개발결과의파급효과 - 본연구의성과물을이용하여향후에, discrete micron-sized beam의치료효과증진요소에대한과학적기반을확인해주는연구성과를얻게된다면, discrete micron-sized beam 치료기술이방사선치료의새로운 protocol로서실용가치를가지고있음이확인되고결과적으로, 방사선종양치료기술의선진화라는무형의성과와함께 discrete multiple micron-sized beam 발생장치또는부속품의제작, 판매라는향후산업활동에동반되는경제수익효과도기대할수있음. 3. 연구개발결과에대한활용가능성 - mm 공간분해능을가진 radiochromic film은 micron-sized beam 조사환경에서피폭체의선량분포양상을보다구체적으로파악하는데유용한도구가됨. - 단순화된 phantom 구성특성하에서, 실험자가구조와재료면에서 phantom을재구성하기가용이하므로 ( 확보가용이한재료이용과국내업체에제작의뢰 ) phantom 이보다다양한방법으로이용될수있을것임. 4. 연구개발수행노력의성실도 - 당초계획한연구내용을 100% 달성하였고, 연구결과물의이용도를높일수있도 록, 빔조사설비의운영사양을강화하는추가적인작업을수행하였음. 5. 공개발표된연구개발성과 ( 논문 지적재산권 발표회개최등 ) 년 7월 5th International Symposium on Radiation safety and Detection Technology 국제학술대회논문발표 1건 - SCI (Journal of Nuclear Science and Technology) 에논문발간이수락되었으나발간을철회하였음 년 10월 15th International Symposium on Mirodosimetry 국제학술대회논문발표 2건기술지원 년 5월한국원자력학회춘계학술대회논문발표 1건기술지원. 비고 : 각평가항목에따라자체평가한내용을상세하게기술 ( 각항목별 200자이내 )

66 Ⅱ. 연구목표달성도 번호세부연구목표달성내용 달성도 (%) - Gafchromic film dose calibration function 1 radiochromic film dosimetry. - mm 50cGy 300cGy radiochromic film dosimetry system - double-checking in bio-experiments radiochromic film dosimetry brain matter-equivalent RW3, PMMA, clear polystyrene 2 brain tissue-equivalent composition. - brain matter-like material RW3 - bone-equivalent calcium hydroxy apatite (CHA) polyvinyl alcohol (PVA) skull-like material 41% : 59% CHA+PVA 3 brain phantom. - skull-like material aluminum photon slowing-down - RW3 PMMA phantom aluminum skull-equivalent material, PMMA brain matter-equivalent material 4 brain tissue-equivalent phantom. - micron-sized beam collimation - mm radiochromic film micron-sized beam brain beam dispersion micron-sized beam protocol

67 Ⅲ. 종합의견 1. 연구개발결과에대한종합의견 - 당초계획한연구목표를 100% 달성하고, 당초계획과는별도로연구결과물의향후이용도를극대화하기위한기반장치를설치하고장치기능성을평가하였음. 이러한실험설비강화를통해, 본연구성과물의효용성이높아졌음. 2. 평가시고려할사항또는요구사항 - 1차년도연구결과물로서 SCI 저널게재가확인된논문과관련하여, 저널측의운영상오류로연구수행자의본의아니게게재를철회하게되었음을보고함. - 본연구의수행과정에서다수의타연구지원작업이수행되었는바, 타과제의연구결과물로서성과보고가있을것임. 3. 연구개발결과의활용방안및향후조치에대한의견 - 본연구의결과물인 film dosimetry 체계와 brain phantom은, 향후 discrete micron-sized beam therapy protocol 완성에직접적으로기여할것임. - 연구수행시이용한 gafchromic EBT film이최근에 EBT-2 film으로사양변동이발생한이유로, EBT-2 기반의 dose calibration 작업이현재진행되고있음. Ⅳ. 보안성검토 1. 연구책임자의의견 - 해당사항없음. 2. 연구기관자체의검토결과

68 수정 보완요구사항대비표 과제명 : Radiochromic Film 을이용한저선량피폭측정용 Brain Phantom 개발 주관기관 ( 책임자 ) : 서울대학교 ( 김은희 ) 전문기관의수정 보완요구사항 - Head phantom 내에서의 dose dispersion 을예측치와비교하거나또는이와관련한제반문제점등을종합적으로정리할필요가있음. 주 1) 수정 보완요구사항반영내용요약 - 일반적으로컴퓨터모사계산을통해 phantom 내선량분포를계산할수있음. 그러나, 본연구에서다루는 150 kv bresmsstrahlung X-ray 를선원으로하는 microbeam 을 phantom 깊은지점까지전달하여유의미한선량분포를얻기까지는수일의계산시간이요됨. 실제측정에서는단순히 tube current 를큰값으로하거나 film 의방사선노출시간을올리는것으로쉽게분포특성자료를얻을수있어애초에 film 을이용한실측을실시한것임. 주 2) 비고 pp 추가함. - 계획대로구체적으로수행되었으나논문발표실적이부족하여개선하여야함 년국제학회발표논문 1 건이 peer review 를통해 Journal of Nuclear Science and Technology (SCI) 에수록발간이예정된상황에서, 학회주관처의행정변경으로저널발간이중단되는사고가발생한바있음 (2010 년 8 월 12 일주관처로부터통지 ). - 본연구결과물을내용으로하는 SCI journal 제출원고에대한 review 가진행중임. 향후추가논문성과에대해등록할것임. - 정량적연구성과물, 자체평가의견서누락 - 평가용보고서에첨부하여제본책자로제출한바있음. 평가자에게자료전달이되지않은것인지, 평가자가전달된자료를미처확인하지못한것인지는, 본연구수행자의관리범위를벗어남. 주 수정 보완반영내용은반드시최종보고서 에반영하고경우에따라별지를사용하여작성하기바람 주 비고란에는수정 보완요구사항을반영한최종보고서의해당 를기입하고별지가있을경우별지의제목을기입할것