ARDMS SPI STUDY GUIDE WITH QUESTIONS AND VERIED ANSWERS ALREADY GRADED A

ARDMS SPI STUDY GUIDE WITH QUES TIONS AND VERIED ANSWERS ALREADY GRADED A In soft tissue, if the frequency of a wave is increased the Propagation Speed (PS) will... - ANSWER>> Remain the Same because stiffness and density affect Propagation Speed. What is the audible range? - ANSWER >>20 -20,000Hz >20,000Hz=Ultrasound Frequency is measured in - ANSWER>>Hertz (Hz) is Cycles per Second Not affected by sonographer Increase Frequency; Decrease Depth A period is the length of time it takes for - ANSWER>>one complete wavelength to pass a fixed point PRP is determined by - ANSWER>>Transmit time and receive time. Period is measured in - ANSWER>>Time (μs) When the son ographer changes the imaging depth what parameters are changed? - ANSWER>>PRP, PRF, Duty Factor What is duty factor? - ANSWER>>The percentage or fraction of time that the system is transmitting a pulse (Time Sound is ON or ON -Time). Propagation Speed in SOFT TISSUE - ANSWER>>1.54 mm/μs (1540 m/sec) Unit of measurement for Pulse Duration, Duty Factor, PRP, and Period - ANSWER>>Time, (μs) Pulse duration is determined by - ANSWER>>Sound Source Only Pulse Duration is controlled by - ANSWER>>the ultrasound system and transducer Pulse Duration Formula - ANSWER>>pulse duration (μs) = # cycles in pulse/frequency(MHz) PD= Number of cycles in Pulse/ Frequency(Hz) Spatial Pulse Length (SPL) (measurement) - ANSWER>>The distance that a pulse occupies in space from the start to the end of a pulse. (mm) Typical values for spatial pulse length in soft tissue. - ANSWER>>0.1 to 1.0 mm Spatial pulse length is determined by - ANSWER>>sound source and medium Spatial Pulse Length is directly proportional to - ANSWER>>the Number of Cycles in the Pulse and the Wavelength (Directly Proportional means that increased SPL will increase both the number of cycles in the pulse and the wavelength if increased). Spatial pulse length is inversely proportional to - ANSWER>>Frequency (MHz) (Inversely Proportional means that increased SPL will lower frequency. This is because axial resolution is better with lower frequency) Pulse Dura tion (PD) - ANSWER>>The actual time from the start of a pulse to the end of that pulse; a single transmit, talking, or "on" time. Time the pulse is on typically measured in (ms). Pulse Length - ANSWER>>The distance of the pulse start to end or the durati on or length of a single pulse Pulse Length is typically measured in (mm). the ability of an object to resist compression and relates to the hardness of a medium? - ANSWER>>Stiffness. Think: ↑ Stiffness ↑ Speed ↓ Density ↑ Speed An increase in pulse repetition frequency would lead to: - ANSWER>>Increasing pulse repetition frequency, increases duty factor. ↑ PRF ↑ Duty Factor Which of the following would have the highest propagation speed? - ANSWER>>Bone has the highest propagati on speed, at 2000 -4000 m/s. What has the lowest propagation speed? - ANSWER>>air technically has the lowest propagation speed at 300 m/s