PowerPoint 프레젠테이션

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1 초음파물리학 Dept. of Radiological Science Hanseo University

2 reflection < 그림 7-1> specular reflection diffuse reflection scattering 발생 scattering < 그림 7-2> 흩어짐 많은진단정보제공 hyperechoic : 음향산란이주변조직보다큰영역 ( 과다반사지역 ), 영상이밝게보임 hypoechoic : 음향산란이주변조직보다작은영역 ( 과소반사지역 ), 영상이어둡게보임

3 Texture (speckle) 초음파영상에서점들의배열 ( 산란 + 반사 ) < 그림 7-3> A : 7MHz B : 3.5MHz 밝은점 : 보강간섭어두운점 : 상쇄간섭 artifact 의종류 (1) reverberation artifact (2) comet-tail artifact (3) ring-down artifact (4) mirror image artifact (5) Doppler spectral mirroring (6) beam width artifact (7) side-lobe artifact (8) grating lobe artifact (9) slice thickness artifact

4 1. The amplitude of an echo from a specular reflector depends on each of the following except: A. Angle B. Attenuation C. Pulse repetition frequency D. Distance 2. Another name for an interface that reflects sound in all directions is a: A. Specular reflector B. Organ boundary C. Scatter D. Attenuator 1

5 5. The granular dot display of organ parenchyma on a twodimensional B-scan image is also known as: A. Speckle B. Sparkle C. Points of light D. Points of scatter 6. Which of the following phenomenona is most closely related to the production of texture on a B-mode image of a uniform organ or a tissue phantom? A. Refraction B. Shadowing C. Interference D. Reverberation 1

6 reverberation artifact 반사체에서다중반사를만들어냄 거리의두배에대응하여나타냄 예 ) fat - fascia - muscle body wall - soft tissue - bone < 그림 7-6, 7, 8>

7 comet-tail artifact 다중반사의일종 금속물질내에서의다중반사 < 그림 7-9, 10, 11>

8 ring-down artifact gas, 기포가많은곳에서의다중반사 comit-tail artifact의생성과거의유사 발생 : diaphragm, larynx, pharynx, bowel, wall of gallbladder < 그림 7-12, 13>

9 mirror image artifact 뼈나공기접합면처럼매우강한반사체가있는영역에서발생 < 그림 7-14, 15, 16>

10 Doppler spectral mirring < 그림 7-17> 실제의스팩트럼으로부터스팩트럼기준선반대편에서나타남 발생원인 - high gain < 그림 7-18> - cosφ = 90 일때 < 그림 7-19>, < 그림 7-20>

11 beam width artifact point like phantom 측방향분해능을측정하기위해사용 beam width에관계 점같은반사체에주사될때 B-mode는선으로나타남 < 그림 7-21> : 선의크기 = 빔폭의크기

12 beam width artifact 의형태 < 그림 7-22, 23> 7-22 : single transducer 7-23 : array transducer A : point like target B : tube (2~8mm) single transducer array transducer

13 side lobe artifact < 그림 7-25> grating lobe artifact < 그림 7-26, 27>

14 slice thickness artifact 빔폭효과와유사 단면두께는빔폭에수직 크기 : 단면두께 > 빔폭 < 그림 7-28> : slice thickness가넓으면영상이부분적으로퍼짐 < 그림 7-29> : 5mm 직경무반사물체

15 < 그림 7-30> : 6mm 직경의 tube phantom, depth=3mm A : 넓은 slice thickness 를가진 3.5MHz phased array B : 좁은 slice thickness 를가진 5MHz linear array

16 < 그림 7-31> - B-mode 영상에서보여지는주사면의표현 - 표면근처 넓음 - 단면두께초점거리 좁아짐 - 먼영역 다시넓어짐

17 유용한 artifact (= shadowing, enhancement) < 그림 7-33> low attenuation mass enhancement (high amplitude) high attenuation mass partial shadow (low amplitude) air total shadow (no echo)

18 Enhancement Partial shadow Shadowing

19 13. Doppler spectral mirroring occurs for: A. Flow through an artery located at a large distance B. A Doppler angle of 90 degrees C. venous flow only D. Arterial flow only 14. The lateral spreading of the image of a pointlike reflector is due to: A. Beam width effects B. Speed of sound artifacts C. The doppler effect D. Refraction effects 1

$refraction artifact 굴절 매질의음속 fat : 상당한굴절아티팩트를발생시킬수있음 실제와다른위치에서영상이나타남 < 그림$

20 refraction artifact 굴절 매질의음속 fat : 상당한굴절아티팩트를발생시킬수있음 실제와다른위치에서영상이나타남 < 그림 7-37> : 굴절에의한물체영상의측면이동 A : 실제물체를통과하나나타나지않음 B : 물체가검출 C : 최종영상 아래쪽물체가왼쪽으로이동

21 19. The opposite of echo enhancement is: A. Detection B. Obliteration C. Shadowing D. Good through-transmission 20. If refraction occurs, the machine: A. Uses Snell's law to compute reflector positions B. Places echo dots along lines corresponding to refracted beams C. Places echo dots along lines corresponding to nonrefracted beams D. Cannot receive echo signals from the medium 1

22 speed of sound artifact < 그림 7-42> : soft tissue (1540 m/s) 1540 m/s < 반사신호의시간이적게걸림 = 실제거리보다가깝게표시 1540 m/s > 반사신호의시간이오래걸림 = 실제거리보다멀리표시

23 3. Echoes from scatterers sometimes appear brighter on the display than echoes from organ boundaries because: A. Scatterers exhibit angular effects B. Organ boundaries enhibit angular effects C. Scatterers are larger in diameter than boundary interfaces D. Scatterers are not accompanied by tissue attenuation 4. The term hyperechoic signifies a region that has A. Fewer sources of echoes than other regions B. Interfaces that have high impedance C. Elevated echogenicity D. No reflectors 1

24 7. "Structures and features on an image that do not have a one-to-one correspondence to the object being scanned" is a definition of: A. Reverberations B. refraction C. Speckle D. Artifacts 8. When a two-dimensional B-mode image is constructed, echo dots are positioned: A. Anywhere on the image, but at a depth corresponding to the echo arrival time B. Along the transmitted beam axis C. At random locations in the beam D. Along a line corresponding to the lateral margins of the beam 1

25 9. Many echoes generated from the same interface describes: A. Refraction B. Speckle C. Reverberation D. Attenuation 10. An interface is located 2 cm from the transducer. If a single reverberation occurs, the reverberation echo would be found at a depth of: A. 1 cm B. 2 cm C. 4 cm D. 8cm 1

26 11. A series of echoes below the position of a metallic object on a B- mode image is most likely due to: A. Reverberations within the object B. Reaction of the tissue distal to the object C. Reaction of the tissue proximal to the object D. Enhancement caused by low attenuation by the object 12. Echoes appearing to arise distal to near-perfect reflectors such as the diaphragm can often be attributed to: A. Refraction of the beam beyond the reflector B. Mirror image artifacts C. Attenuation of the beam by structures distal to the reflector D. Echo enhancement by the reflector 1

27 15. Artifactual fill-in on images of anechoic tubes whose axes are perpendicular to the ultrasound beam way be attributed to: A. Beam width effects B. Slice thickness effects C. Echoes arriving from within the tubes D. Echoes arriving from distal to the tubes 16. Which of the following types of effects occur with a linear array transducer but not a single element transducer? A. Beam width effects B. Side lobe effects C. Grating lobes D. Reverberations 1

28 17. Artifactual fill-in on images of anechoic spheres may be attributed primarily to: A. Beam width effects B. Slice thickness effects C. Echoes arriving from within the spheres D. Echoes arriving form distal to the spheres 18. Echo enhancement most noticeably affects signals arising from a low attenuating object. A. Within B. Proximal to C. Lateral to D. Distal to 1

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PowerPoint 프레젠테이션

PowerPoint 프레젠테이션 초음파물리학 Dept. of Radiological Science Hanseo University 초음파장비의정도관리 정도관리 QC (Quality Control) : 품질관리 QA (Quality Assurance) : 품질보증 PM (Preventive Maintenance) : 예방점검 Tissue-mimicking phantom 초음파장비의 QA에사용