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 the textbook:

ULTRASOUND IMAGING AND INSTRUMENTATION

Pulse-echo Imaging Voltage Sound Rectification Amplification Compensation Demodulation Compression Rejection Scan conversion Preprocessing Postprocessing Magnification

TRANSDUCER EXCITATION AND OUTPUT POWER TRANSMITTER TRANSMIT POWER OUTPUT ACOUSTIC POWER ENERGY OUTPUT

TIMING PRF >1000 Hz

RECEIVER TGC GAIN MASTER GAIN OVERALL GAIN

TIME GAIN COMPENSATION

GAIN vs. OUTPUT

TGC INCORRECT SETTINGS

DYNAMIC RANGE DYNAMIC RANGE COMPRESSION LOG COMPRESSION COMPRESS

DYNAMIC RANGE 50 db 30 db

NOISE REDUCTION REJECT low-level echoes (noise) anechoic BEFORE REJECT AFTER REJECT

NOISE REDUCTION Frame averaging (persistence) Frequency compounding Spatial compounding

HARMONICS A wave whose frequency is a whole-number multiple of that of another

DISPLAY MODES

2D & M-mode B-SCAN (2-D) M-MODE

B-scan

PATIENT-ORIENTED B-SCAN PLANES

ORGAN-ORIENTED B-SCAN PLANES

B-SCAN WITH A-SCAN OPHTHALMIC IMAGE

OBSTETRICAL IMAGES 2D 3D

Answers to the following FIFTEEN practice questions were derived from material in the textbook:

Question 1 Which of the following controls is part of the receiver in a pulse-echo ultrasound system? BRIGHTNESS XMTR PWR RES TGC POST PROCESSING Page 28

Question 2 The sensitivity of an ultrasound system may be determined by measuring the duty factor strongest echoes that are received bandwidth amplitude range of the received echoes weakest echoes that are received Page 27

Question 3 If the OVERALL GAIN is decreased, only the brightness of the near echoes will decrease the energy to the patient is decreased the brightness of all echoes will decrease equally the frequency will decrease only the brightness of the far echoes will decrease Page 28

Question 4 If the ultrasound system displays only the echoes from strong reflectors and nothing else, the sonographer should increase the lateral resolution decrease the output power increase the overall gain decrease the slope of the TGC adjust the far gain Page 28

Question 5 The control that is used to suppress unwanted, low level echoes or background information is TGC POST PROCESSING DYNAMIC RANGE REJECT WRITE MAGNIFICATION Page 29

Question 6 Electrical interference could appear in an image as shadowing behind a poorly attenuating structure a decrease in far field penetration enhancement behind a highly reflective structure low-level echoes within a cyst a loss of axial resolution Page 29

Question 7 The receiver dynamic range that provides the best opportunity for the display of a wide range of gray shades is 3 db 6 db 9 db 60 db 0 db Page 29

Question 8 Compression is used in the receiver of an ultrasound system to reduce the duty factor increase the difference between small and large amplitude signals reduce the range of signal amplitudes provide post processing reduce the sound energy entering the patient Page 29

Question 9 The OUTPUT control on a pulse-echo ultrasound system controls the amount of amplification in the receiver varies the dynamic range in the receiver is used to equalize differences in received echo amplitudes due to differences in the depths of the reflectors varies the voltage that the beamformer supplies to the transducer does not have any affect on the amount of sound energy that enters a patient Page 26

Question 10 The OUTPUT control in a pulse-echo system does NOT affect the excitation voltage that is applied to the transducer frequency of the sound that leaves the transducer energy that enters the patient amount of energy leaving a transducer overall gain that may be required Page 26

Question 11 From a safety standpoint, which one of the following methods is BEST? Low transmitter output and high receiver gain High near gain and low far gain High reject and high transmitter output High transmitter output and low receiver gain Low near gain and high far gain Page 28

Question 12 The dynamic range of the receiver of an ultrasound system refers to the ability of the receiver to track a rapidly moving structure range of echo signal frequencies that can be processed without distortion speed with which the receiver recovers following the excitation pulse to the transducer depth range in tissue over which moving echoes can be received range of echo signal amplitudes that can be processed without distortion Page 29

Question 13 Which of the following results in an increased acoustic exposure to the patient? application of reject increase in the swept gain slope rate increase in the television monitor brightness increase in the beamformer voltage to the transducer increase in the overall gain Page 26

Question 14 Which of the following is NOT a brightness-modulated display, based on the amplitude of received echoes? B mode B scan A mode Real time gray scale M mode Page 31

Question 15 Increasing the gain of a pulse-echo system results in higher A-mode echoes. This is due to increased amount of sound emitted by the transducer increased amount of sound reflected increased efficiency of transducer conversion of sound into electricity increased amplification in the receiver decreased amplification in the receiver Pages 28 and 31

END OF LESSON 06 For information on the accompanying textbook, visit the Website: www.sonicorinc.com