SPI ULTRASOUND REGISTRY REVIEW|UPDATED&VERIFIED|GUARANTEED SUCCESS

SPL wavelength x # of cycles With phased array transducers, the transmitted sound beam is steered by Varying the timing of pulses to the individual piezoelectric elements What type of wave is sound? mechanical and longitudinal The Frequency ranges for Ultrasound are: > 20,000 Hz (20kHz) The speed of sound in soft tissue is: 1540 m/s Linear sequence Array transducer that fires the elements in groups Unit for Wavelength is millimeters Enhancement is caused by weakly attenuating structures (such as a cyst) The wavelength in a material having a propagation speed of 1.5 mm/us employing a transducer frequency of 5.0 MHz is: 0.3 mm Wavelength= c/f = 1.5mm/us ÷ 5MHz = 0.3mm An ultrasound transducer converts: electrical energy into mechanical energy and vice versa The order of attenuation, from the lowest attenuation to highest: fat, muscle, bone, air Propagation Speed from the lowest to highest: air, fat, muscle, bone If the frequency doubled, what to wavelength? Decrease by one half/ Frequency and wavelength are inversely related What happened to intensity if the amplitude of a signal is halve? Quarted/ Intensity is proportional to the amplitude squared, so if the amplitude is halved, the resulting intensity is one fourth the original intensity Duty factor is the percentage of the time the sound is being transmitted A 3dB gain would indicated in intensity by: 2 times (A gain of 3dB results in doubling of intensity (or power)) Ignoring the effects of attenuation, the intensity of ultrasound beam is usually greater at the focal zone because of: The smaller beam diameter (Intensity equals power divided by area. The area is smallest in the focal zone; therefore, the intensity is highest) Attenuation denotes: is the weakening of the strength of the beam, typically from absorption, reflection, or scattering SATA is the lowest of the intensities Beam Uniformity Ratio BUR= SP/SA Continuous Wave Doppler has a duty factor of: 100% SPL The spatial pulse length is defined as the product of the wavelength and the number of cycles in a pulse (SPL= wavelength time the number of cycles in the pulse) SPTP highest intensity The unit for impedance is ________. Rayl ALARA stands for As Low As Reasonably Achievable Snell's law describes: refraction at an interface Matching Layer Has an impedance between skin and the active element so more sound energy is transmitted between the crystal and skin Quality Factor operating frequency/bandwidth spatial resolution is the ability to discern two closely reflectors as individual reflectors Infrasound Sound waves with a frequency less than 20 Hz Pascual (Pa) unit for pressure amplitude W/cm2 unit for intensity Pulse Repetition Frequency the number of pulses per second Spatial Pulse Length (SPL) Distance that a pulse occupies in space; distance from start of a pulse to end of that pulse Hydrophone used to test output intensity Huygen's Principle states that waves are the result of the interference of many wavelets produced at the face of the transducer A-mode the amplitude of the reflector along the y-axis B-mode Brightness mode of the dot, which is considered in the z-axis of the image Axial resolution is determined by spatial pulse length Improve axial resolution decreasing the numbers of cycles in a pulse, or increasing frequency With phased array transducers, the transmitted sound beam is steered by: Varying the timing of pulses to the individual piezoelectric elements If the gain of an amplifier is 18 dB, what is the new gain if the power is reduced by half? 15 dB SATA lowest intensity If the amplitud of a wave is increased threefold, the power will: increased ninefold Ultrasound attenuates an average of ____ dB/cm of travel for each megahertz of frequency. 0.7 It the intensity transmition coefficient (ITC) is 0.74, the intensity reflection coefficient (IRC) will be: 0.26 Acoustic impedance is define as the product of: the speed of sound in tissue and density of the tissue Rayleigh scattering is an example of: a reflector whose size is smaller than the wavelength