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Physics final
| Question | Answer |
|---|---|
| What happens to venous flow in the legs during inspiration? | Decreases |
| Which of the following determines spatial resolution of digital display? | Pixel density |
| Which of the following determines spatial resolution of regular display ? | Number of lines on the display |
| When creating an ultrasound image all of the following assumptions are made except | All structures create reflections of equal magnitude |
| Which statement regarding axial resolution is incorrect ? | Axial resolution is not related to beam diameter . It is related to the length of the pulse |
| Which of the following statements is true about lateral resolution? | It can be improved by focusing |
| Which one of these artifacts does not result from multiple reflections ? | Enhancement |
| What angle is no Doppler shift ? | 90 degrees |
| What is the arterial pressure measured in the toe of an upright person? | 240mmHg |
| Where are harmonics created? | The tissues |
| What non linear behavior creates contrast harmonics | Micro bubble |
| What is DICOM | Protocols for medical image data |
| With frequency compounding how many pulses are transmitted down each scan line? | 1 |
| Which of the following technologies uses long sound pulses to create an image | Coded excitation |
| What is the primary disadvantage of videotape and computer and disc methods of image archiving | Data stored on videotape computer docs can be erased by strong magnetic fields |
| Which of the following statements about pixels is false | It displays up to 3 gray shades simultaneously |
| Which electronic component is required for gray scale imaging | Scan converter |
| Which of the following scan converters will provide the best spatial resolution | 1000 x 1000 pixels |
| This type of pulser generates a single electrical spike which ultimately creates a single sound pulse | Pulsed wave/ single crystal |
| The acoustic power of a sound beam emitted from a transducer is determined by the _______ of the pulser signal | Voltage |
| All of the following are functions of the receiver except | Attenuation |
| All of the following are components of an ultrasound system except | Alternator |
| When the frame rate is 10 Hz how long does it take to create a frame | 1/10 of a second or 130us |
| Under certain conditions an ultrasound system creates each image in 0.01 seconds. What is the frame rate | 100 Hz |
| What is the fundamental limitation of temporal resolution | Speed of sound in medium |
| Things that degrade temporal resolution | Lower frame rate, deeper imaging, multi-focus |
| What is the frame rate if each image of the ultrasound system is created in 0.02 seconds? | 50 Hz or 50 per second |
| Which of the following is most Important in determining the frame rate of a system | Depth of view and speed of sound in medium |
| Which of the following forms of resolutions improves when frame rate increases | Temporal |
| All of the following decrease temporal resolution except | Narrower sector |
| Which of the following will improve a systems Temporal resolution | Increased PRF |
| A sonographer adjust an ultrasound scan to double the depth of view from 5cm to 10 cm what happens to the frame rate | It’s is halved |
| A sonographer adjusts an ultrasound machine to change the sector size from 90 to 45 degrees. Nothing else changes. What happens to the frame rate | It is doubled |
| A linear phased array transducer has 128 crystals. How many of these crystals are fired to create a single sound beam? | 128 |
| Which of the following improves elevational resolution ? | One and one half dimensional array |
| Which of the following transducers is best described as mechanically steered and multi focus? | Annular phased array transducer |
| Which of the following transducers is best described as mechanically steered and single focused ? | Mechanical |
| Which of the following transducers creates a rectangular shaped image? | Linear sequential array |
| What is the best estimate for resolution at 7cm | 5mm |
| Which of the following transducers has the poorest axial resolution | 1.7 MHz and 5 cycles ( low frequency with more pulses) |
| In soft tissue a 3 cycle 1 MHz pulse has a pulse length equal to 4.5mm what is the axial resolution | 2.25mm |
| At what location is sound beam diameter 3 times greater than transducer diameter ? | At a depth equal to four focal lengths |
| What is the shape of a sound beam created by a tiny piece of pzt? | |
| V shaped | |
| What is the ability to accurately distinguish 2 structures lying close together called | Resolution |
| The ability to distinguish 2 structures lying close together front to back or parallel to the sound beam is called | Longitudinal, axial, range, radial, or depth resolution |
| If there are more cycles in a pulse the numerical value of range resolution is | Greater/longer |
| If the beam width is decreased the resolution is | Lateral resolution improves |
| ______ frequency transducers generally have better range resolution | High |
| Which transducer has the worst axial resolution | Low frequency with more pulses |
| Which of the following transducers has best radial (axial) resolution | High frequency with short pulses |
| Two different transducers create sound pulses. One transducer is labeled 5mhz and the other 3mhz. Which transducer is more likely to create a more accurate image with respect to axial resolution | 5 MHz |
| If a new pulsed transducer has many more cycles in its pulse the image accuracy | Degrades |
| If the diameter of a sound beam is 8mm at a depth equal to twice the near zone length, then the pzt crystal has a diameter of 16 mm | False |
| If the diameter of the acoustic beam produced by a crystal is 8 mm at a depth of twice the near zone length then the pzt crystal has a diameter of 8mm | True |
| Azimuthal resolution is also known as | Lateral resolution |
| The length of a pulse is 8 mm what is the minimum distance between 2 reflectors positioned one in front of the other that still produces two echoes on our image? | 4mm |
| The frequency of the transducer does not change. If the diameter of the new piezoelectric crystal increases what happens to the near zone length | Increases |
| The frequency of the transducer does not change if the diameter of the new piezoelectric crystal increases what happens to the far zone length | Decreases |
| The frequency of the transducer does not change if the diameter of the new piezoelectric crystal increases what happens to the wavelength | No change |
| At what location is the sound beam diameter three times greater than the transducer diameter | At the depth equal to four focal lengths |
| Which of the following locations is the deepest part of a sound beam | Fraunhofer zone/ far zone |
| What is the shallowest part of a sound beam | Near zone |
| Line density and frame rate are | Inversely related |
| Lateral resolution improves with ______ focusing | Multi |
| Which statement about color Doppler is least correct | Color Doppler provides accurate quantitative flow analysis |
| Identify the spectral Doppler artifacts | Aliasing, nyquist limit, range ambiguity , mirror image, noise |
| What increases nyquist limit? | Increase PRF |
| What is the only display mode that provides information regarding reflector motion with respect to time | M mode |
| What is the frame rate if each image of an ultrasound system is created in 0.02 seconds | 50 hz |
| What artifact is produced by a single element transducer | Side lobe |
| Slice thickness is also known as | Elevational resolution |
Created by:
Senoye1