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U.S. Physics WB 2/2
Sections 6-10
| Question | Answer |
|---|---|
| The portion of the ultrasound system that stores the image before it is displayed is called: | Scan converter |
| What form are the signals as they leave the receiver? | Analog |
| Analog signals are converted to digital signals for accurate and reproducible processing: (True or False) | TRUE |
| Approximately how large a range of gray shades can the human eye distinguish? | 20 to 30 db |
| The number of bits in the memory bit depth determines how many shades of gray in an image. (True or False) | TRUE |
| The type of scan converter that stores electrical charges is the: | Analog |
| How many shades of gray do most current ultrasound imaging systems have? | 256 |
| What is the decimal equivalent for the binary number 01100011? | 99 |
| The ratio of the largest to the smallest power, or amplitude that a system can use: | Dynamic range |
| A digital scan converter matrix 6 bit depth produces ________ shades of gray | 64 |
| In the memory, the equivalent to a pixel is the: | Bit |
| Which control affects how much amplification is achieved in the receiver? | Gain |
| What does persistence use to create a smooth image with less noise? | Frame averaging |
| The two categories of energy that make up total fluid energy are: | Potential and kinetic energy |
| Which statement about potential energy is least correct? A. potential energy is stored energy B. same as kinetic energy C. Comes in two forms; intravascular and hydrostatic (gravitational) pressure | Same as kinetic energy |
| When there is a pressure gradient along the length of an artery, there is a corresponding loss of energy. This describes: | Poiseuille's Law |
| As resistance of blood flow through the artery increases, the pressure drop across artery will: | Increase |
| As the vessel lumen size decreases, blood flow velocity will: | Increase |
| When the vessel lumen size increases, blood flow velocity will: | Decrease |
| If the radius of a blood vessel is decreased by one half, the velocity of the blood flow will: | Increase four fold |
| The inverse relationship between pressure and velocity is described by: | Bernoulli's equation |
| A high Reynold's number indicates ______ flow. | Turbulent |
| The primary contributing factor(s) to venous blood flow in the upper AND lower extremity include: -heart contraction -intraluminal blood pressure -peripheral resistance in the capillary bed - All of the above | -heart contraction -intraluminal blood pressure -peripheral resistance in the capillary bed |
| When collateral blood flow develops, resistance at that level will: | Decrease |
| When a patient with a stenotic lesion is exercised, the pressure gradient at the site of the stenosis will: | Increase |
| Which of the following is NOT a function of the veins? -Regulate body temperature -Control rate of blood return to the heart -Store blood -Control oxygen to the legs | Control oxygen to the legs |
| Transmural pressure is the difference or gradient between the intramural and tissue pressure. (True or false) | TRUE |
| When tissue pressure exceeds intramural pressure, the veins will: | Compress |
| If the right atrial pressure or a central venous pressure is increased, the veins in the body usually are: | Dilated |
| A Reynolds number greater than ______ is seen with turbulent flow. | 2000 |
| All of the following conditions will elevate right heart pressures except: -mitral regurgitation -tricuspid regurgitation -tricuspid stenosis -congestive heart failure | Mitral regurgitation |
| Which mechanism most reduces intramural and transmural pressure in the veins of a normal patient? | Calf muscle pump |
| The factor(s) affecting blood flow within the body include: | -density of the blood -velocity of flow -size of the vessel |
| The difference between the transmit frequency and the received frequency is called the: | Doppler shift |
| What angle provides the maximum Doppler shift? | 0° |
| Continuous wave Doppler utilizes ______ elements | 2 |
| Flow towards the transducer is displayed ______ the 0 baseline | Above |
| The range of Doppler shift frequencies are: | 20 - 20,000 Hz |
| The Nyquist limit is equal to _____ of PRF | 1/2 |
| Frequency shifts that are angled corrected are converted to cm/sec and then are: | Quantitative information |
| Which statement about Pulsed Doppler PRF is most correct? -always adjust first to fix aliasing -is set by the manufacturer -PRF is limited by depth of flow -when adjusted changes the value of the Doppler shifted frequency | PRF is limited by depth of flow |
| Aliasing is a diagnostic parameter for severe disease (True or false) | False (aliasing is an artifact that occurs when the Doppler shift exceeds the Nyquist limit) |
| Window filling of the spectral tracing is caused by all the following except: -turbulent flow -sample gate to small -sample volume placed too close to vessel wall -Doppler gain too high -somewhat inherent in electronic linear array probes | Sample gate too small |
| The maximum amount of turbulence is usually detected: | Distal to site of stenosis |
| Blood moving faster than 1/2 the PRF setting will alias: (True or false) | TRUE |
| Color flow Doppler provides _______ velocity information's | Average & Qualitative |
| The color assigned to flow towards the transducer is: | Red |
| The type of processing utilized with most color flow systems is: | Autocorrelation |
| The minimum number of pulses per line required to assign a color is: | 3 |
| Color aliasing is seen when red and blue colors are separated by black. ( true or false ) | FALSE |
| No flow within a vessel would be indicated by a ____ color. | BLACK |
| Color frame rate is affected by all of the following except: - Sector Size -Color box size - Color gain - PRF | Color Gain |
| The purpose of the wall filter ( high pass filter ) is to: | -Filter out motion artifacts -Eliminate high amplitude noise artifacts |
| On color flow imaging, the best way to overcome aliasing is: | use a higher PRF number |
| The color priority on color flow instruments is used to: | decide the relative contribution of color/echoes on the image |
| The color map represents the: | mean Doppler shifts only |
| The angle corrector is used to: | align the ultrasound beam with vessel lumen |
| Aliasing is found in all of the following imaging modes except: -Color Doppler -CW Doppler -Spectral Pulsed Doppler | CW Doppler |
| Power Doppler (is): -used to detect slow flow -looks at amplitude of doppler signal -used to eliminate aliasing -used for finding lumen of high grade stenosis -all of the above | All of the above |
| PWD instruments are characterized because of their ability to do all of the following except: -Real-time duplex imaging & Doppler -Range resolution -No aliasing or velocity limits -detect/demonstrate turbulent flow | No aliasing or velocity limits |
| The method used by CW Doppler to discriminate valuable signals is the: | zero-crossing detector |
| In laminar flow, blood is seen to move: | in layers |
| Autocorrelation processing looks at Doppler data from: | multiple sample volumes |
| An artifact that appears as multiple reflections equally spaced is called: | reverberation |
| Grating lobe artifacts occur with _____ transducers. | array |
| Refraction causes lateral displacement of the reflector and is caused by: | oblique |
| Propagation speed errors occur because the equipment assumes a speed of sound in tissue of 1.54 mm per microsecond. ( True or False ) | TRUE |
| Comet tail artifacts are seen distal to a ______ structure. | highly reflective |
| Select from the following the 2 types of useful artifacts: -mirror image -enhancement -ghosting -side lobes -shadowing -reverberation | Enhancement & Shadowing |
| Mirror image artifacts result from highly reflective interfaces _____ to sound beam. | perpendicular |
| Color mirror image artifacts can be eliminated by: | decreasing output power |
| Aliasing occurs when the reflected frequency exceeds _____ the Nyquist limit: | 1/2 |
| Enhancement occurs when the sound beam travels through a region of ______ than the surrounding tissue. | Lower attenuation |
| The slice thickness of the ultrasound beam will change with focal zone position. (True or False) | TRUE |
| Which one of the following is NOT a function of a test object: -beam thickness -beam profile -accuracy of measured velocities -penetration | beam profile |
| The type of test object that contains gel with small spheres in random positions is the: | PIRTO |
| The type of test object that contains material that has characteristics that are hyperechoic or hypoechoic as compared to material surrounding them: | tissue equivalent phantom |
| The ability to detect disease when disease is actually present: | sensitivity |
| The term used to describe a procedure or test determining that a person does NOT have disease is: | Specificity |
| The formula for Positive predictive value (PV+) is: | True Positives / True Positives + False Positives |
| The ALARA principle relates to: -A) using minimum exposure time -B) using minimum output -C) using adequate gel - D) A & B | -A) using minimum exposure time & -B) using minimum output |
| Frequency, PRP, amplitude, and duty factor can be calculated with an piezoelectric element attached to an oscilloscope. This instrument is called: | hydrophone |
| The 2 mechanisms of bio effects are: | thermal and cavitation |
| Small microbubbles that occur as a result of violent molecular agitations are called: | Cavitation |
| The AIUM has issued a statement saying no confirmed biological effects on patients or instrument operators have been reported at intensities below _____ mW/cm^2. | 100 |
| If cavitation occurs, and the bubbles are not collapsing which type of cavitation is it? | stable |
| This measures the likelihood for cavitation effects to occur? | mechanical index |
| Although ultrasound is non-ionizing, bioeffects can be caused when power & exposure levels are exceeded? ( True or False ) | TRUE |
| High receiver gains will increase the intensity of the sound. (True or false) | FALSE (High output power will increase it) |
| The method of identifying & measuring the parts of ultrasound that have the potential for producing biological effects is called: | dosimetry |
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