Download Ultrasound Attenuation and Reflection and more Exams Nursing in PDF only on Docsity! SPI chapter 6 Test Questions Answered (Latest Update 2023) (Verified Answers) Define attenuation - correct answer ✅Decrease in "bigness" (intensity, power &litude) of a wave as it travels How are attenuation and speed related - correct answer ✅UNRELATED. Three components of attention - correct answer ✅1) absorption 2) scattering 3) reflection Attention unit - correct answer ✅dB (must be negative since attenuation causes intensity to decrease) Less attenuation - correct answer ✅shorter distances, lower frequencies More attenuation - correct answer ✅longer distances, higher frequencies Attenuation in different media - correct answer ✅Air>> bone&lung>> Soft tissue>> blood SPI chapter 6 Test Questions Answered (Latest Update 2023) (Verified Answers) Attenuation & penetration - correct answer ✅In soft tissue lower frequency = less attenuation, we can penetrate further with lower frequency To find total attenuation - correct answer ✅+/- dB NEVER multiply Reflection - correct answer ✅Occurs when propagating sound strikes a boundary between two media and some return to the tx specular reflection - correct answer ✅-reflection from a smooth surface and return in ONE direction, strikes at 90degrees When does specular reflection occur? - correct answer ✅When the wavelength is smaller than boundary irregularities diffuse reflection/ backscatter - correct answer ✅Redirection of sound in ALL directions SPI chapter 6 Test Questions Answered (Latest Update 2023) (Verified Answers) Reflection of a ultrasound wave depends on - correct answer ✅Different acoustic impedances of the media on either side of the boundary Impedance equation - correct answer ✅Impedance (Rayls ) = density(kg/m3) x propspeed (m/s) PORNN - correct answer ✅Perpendicular Orthogonal Right angle Ninety degrees Normal incidence oblique incidence - correct answer ✅Anything other than 90degrees Incident intensity - correct answer ✅Intensity of the wave prior to striking a boundary, w/cm2 SPI chapter 6 Test Questions Answered (Latest Update 2023) (Verified Answers) Reflected intensity - correct answer ✅The intensity after striking a boundary changes directions and returns to where it came from transmitted intensity - correct answer ✅Intensity after striking a boundary continues on in same general direction that it was originally traveling. incident intensity formula - correct answer ✅reflected intensity + transmitted intensity intensity reflection coefficient (IRC) - correct answer ✅percentage of the intensity that bounces back intensity transmission coefficient (ITC) - correct answer ✅percentage of intensity that continues forward after beam strikes a boundary IRC AND ITC unit - correct answer ✅UNITLESS they are percentages IRC AND ITC equation - correct answer ✅100% = IRC + ITC When they are added together the result is ALWAYS 100% SPI chapter 6 Test Questions Answered (Latest Update 2023) (Verified Answers) Reflection With NORMAL incidence - correct answer ✅Reflection occurs only if The two media and the boundary have different acoustic impedances IRC formula - correct answer ✅(Z2-z1)/(z2+z1)2 Z2 is what impedance? - correct answer ✅transmitted impedance (tissue sound is entering) Z1 is what impedance? - correct answer ✅reflected impedance (medium the sound is currently in) With greater impedance differences - correct answer ✅The IRC increases and the amount of reflection increases Transmission with NORMAL incidence - correct answer ✅What ever is not transmitted is reflected
