ARDMS SPI STUDY GUIDE complete and Graded A+

ARDMS SPI STUDY GUIDE complete and Graded A+ In soft tissue, if the frequency of a wave is increased the Propagation Speed (PS) will... Remain the Same because stiffness and density affect Propagation Speed. What is the audible range? 20-20,000Hz 20,000Hz=Ultrasound Frequency is measured in Hertz (Hz) is Cycles per Second Not affected by sonographer Increase Frequency; Decrease Depth A period is the length of time it takes for one complete wavelength to pass a fixed point PRP is determined by Transmit time and receive time. Period is measured in Time (μs) When the sonographer changes the imaging depth what parameters are changed? PRP, PRF, Duty Factor What is duty factor? 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 1.54 mm/μs (1540 m/sec) Unit of measurement for Pulse Duration, Duty Factor, PRP, and Period Time, (μs) Pulse duration is determined by Sound Source Only Pulse Duration is controlled by the ultrasound system and transducer Pulse Duration Formula pulse duration (μs) = # cycles in pulse/frequency(MHz) PD= Number of cycles in Pulse/ Frequency(Hz) Spatial Pulse Length (SPL) (measurement) 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. 0.1 to 1.0 mm Spatial pulse length is determined by sound source and medium Spatial Pulse Length is directly proportional to 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 prop