Sonography Canada Core Review | questions and answers 2023/24

Sonography Canada Core Review | questions and answers 2023/24 f - v/wavelength frequency - number of cycles per second T - 1/f Period - length of time for one cycle 1540 m/s - speed of sound in soft tissue infrasound - <20Hz audible sound - 20Hz-20,000Hz ultrasound - >20,000Hz c - = root (bulk modulus/density) or =stiffness/density bulk modulus - stress/strain I - = P/a P - = E/T Amplitude - maximum deviation from normal A - = max-normal A^2 - proportional to intensity and power PRP - = 1/PRF line time - (PRP) time for one scan line PRF - number pulses per sec PRP/ PRF factors - depth speed of sound PD - =T x # cycles per pulse DF - = PD/PRP SPL - = wavelength x #cycles in one pulse Ax Res - = SPL/2 Range Eqn - d=0.77t Attenuation (eqn) - =0.5fL Attenuation coefficient - 0.5dB/cm soft tissue Z - =cp % reflection - =[z2-z1/z2+z1]^2 bit depth - =2^n IRC - = reflected intensity/incident intensity NZL - = (crystal diam^2 x f)/ 6 Young's Modulus - =3pc^2 or = stress/strain methods with highest thermal risk/ lowest mech risk - CW and PW spectral Methods with lowest thermal risk/ highest mech risk - B mode Isppa - mech risk highest Isppa - 190W/cm^2 Ispta - thermal risk highest Ispta - 720mW/cm^2 AIUM TI recommendations - 11-14wks spectral only with clear benefit TI >0.7 only 5-10min max snell's law - if prop speed increases at media border, refracted angle is greater than incident Huygen's Principle - waves are a result of many small wavelets at transducer face based on constructive interference Aperture - number/ width of crystals creating a beam FR - =PRF/#lines per frame Frame Rate - frames created per second Frame Time - amount of time taken to create one frame Nyquist Limit - =PRF/2