Answer: TGC is needed to amplify echoes from deeper structures so that they appear as bright as similar structures located at more shallow depths.

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1 Q47. When performing a sonogram why the sonographer needs to use the TGC? TGC is needed to amplify echoes from deeper structures so that they appear as bright as similar structures located at more shallow depths. Q48. When TGC is adjusted which component in the ultrasound system implements the changes? Receiver When TGC is adjusted the receiver in the ultrasound system implements the changes. Q49. What is the name of the receiver function that corrects for attenuation? Compensation The time gain compensation (TGC, DGC) control compensates for the attenuation of sound as it propagates through tissues. Q50. What does the dynamic range of the receiver of an ultrasound instrument refers to? The dynamic range of the receiver of an ultrasound instrument refers to the range of echo signal amplitudes that can be processed without distortion. Copyright 2012 Pass Ultrasound Physics Exam 17

2 Q51. What is displayed on the y-axis of an m-mode, b-mode and A-mode image? Y-axis of m-mode b-mode (z-axis) A-mode Information displayed Y-Axis represents depth and is measured by pulse s time of flight Z-Axis represents the amplitude of echoes and is measured by echo strength. Y-Axis represents amplitude of echo and is measured by echo strength. Q52. What is displayed on the x-axis of an m-mode image? X-axis of m-mode b-mode A-mode Information displayed X-Axis represents time. X-Axis represents reflector depth and is measured by pulse s time of flight. X-Axis represents reflector depth and is measured by pulse s time of flight. Q53. In B-mode display what does z-axis represents? Z-Axis represents the amplitude of returning echoes and is measured by echo strength. The brightness of the spot is proportional to the strength of the returning echo. The stronger the returning echo, the brighter the spot. Copyright 2012 Pass Ultrasound Physics Exam 18

3 Q54. How to calculate the number of shades of gray in a pixel? 1 bit = 2 shades of gray 1 bit per pixel = 2 shades (white and black, this is called a bistable image) 2 bits per pixel = 2x2 = 4 shades of gray 3 bits per pixel = 2x2x2 = 8 shades of gray 4 bits per pixel = 2x2x2x2 = 16 shades of gray 8 bits per pixel = 2x2x2x2x2x2x2x2 = 256 shades of gray Q55. What will result in the greatest number of shades of gray in a digital image display? Large pixels with many bits per pixel will result in the greatest number of shades of gray in a digital image display. The more bits per pixel the more shades of gray. Q56. What improves if, number of pixels per inch are increased? More pixels per inch improve the temporal resolution The more pixels per inch, better the temporal resolution. Q57. What is the effect of more pixels in image matrix on spatial resolution? The more pixels per inch, better the spatial resolution. The better spatial resolution is obtained with more pixels in the image matrix, regardless of whether the scan converter is digital or analog. Copyright 2012 Pass Ultrasound Physics Exam 19

4 Q58. Can the gray scale be changed by the sonographer? True. The gray scale can be changed by the sonographer. Compression changes the gray scale mapping. Compression keeps signals within the operating range of the ultrasound system electronics and the gray scale within the range of what we can see. Compression can be adjusted by sonographer therefore gray scale can be changed by the sonographer. Q59. Which component of the ultrasound system that stores digital echo signal information? Scan converter Scan converter is the component of the ultrasound unit which contains the memory bank. The role of scan converter is image storage and scan conversion. Q60. In an analog scan converter, what component stores the image data? dielectric matrix Analog scan converter uses the panel called dielectric matrix to store image information. It divides picture into a 1000 x 1000 matrix. It stores image brightness values as electrical charges. Q61. What component of the US unit contains the memory bank? Scan converter The role of scan converter is image storage and scan conversion. In ultrasound system the scan converter or memory, helps to process the image data and transforms the incoming echo data into a suitable format for the display. Copyright 2012 Pass Ultrasound Physics Exam 20

5 Q.62. What is the elimination of voltages that do not exceed a certain level? Rejection is the elimination of smaller amplitude echoes produced by weaker reflections. Rejection helps to reduce noise by removing low level signals. Q63. What is the definition of pulse repetition frequency? The number of ultrasound pulses emitted per second by an ultrasound machine is pulse repetition frequency. Q64. What is the definition of pulse duration? Pulse duration is the actual time from the start of a pulse to the end of that pulse. Pulse duration is the actual time that an US machines is creating a pulse. Q65. What is the actual time that an US machines is creating a pulse? Pulse duration is the actual time that an US machines is creating a pulse. Q66. What is the definition of pulse repetition period? Pulse repetition period is the time from the start of one pulse to the start of next pulse or time taken for a pulse to occur. It includes the on or transmit time and off or listening time. Copyright 2012 Pass Ultrasound Physics Exam 21

Lesson 06: Pulse-echo Imaging and Display Modes. This lesson contains 22 slides plus 15 multiple-choice questions.

Lesson 06: Pulse-echo Imaging and Display Modes This lesson contains 22 slides plus 15 multiple-choice questions. Accompanying text for the slides in this lesson can be found on pages 26 through 32 in