Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
100 Cards in this Set
- Front
- Back
|
The term "signal-to-noise ratio" denotes: a) The ratio of the electronic noise to the radio frequency noise b) The ratio of the system power to the weakest detectable signal c) The relative amplitude of the signals compared to the amplitude of the noise d) The ratio of the largest to the smallest signal that the system can display e) The ratio of the transducer frequency to the received echo intensity |
c) The relative amplitude of the signals compared to the amplitude of the noise Noise is inherent in all electronic circuits and cannot be totally eliminated. Since noise occurs randomly, it is very difficult to isolate. One method of reducing the display of system noise is frame averaging. The system electronics, power line voltage variations, and radiofrequency interference induce noise, System shielding is a method employed to reduce the presence of noise in the system. The greater the signal-to-noise ratio (SNR) of the imaging instrument, the weaker the signal that can be reliably differentiated from noise. System sensitivity is often defined as its SNR. |
|
|
What receiver function converts the negative portion of the radio frequency (RF) signal to positive? a) Compression b) Demodulation c) Rectification d) Enveloping e) Amplification |
c) Rectification |
|
|
Pre-processing functions may be defined as: a) Any function that can be performed on a frozen image b) A function that takes place in the beam-former and is not controllable by the operator c) A function that allows increased focusing of the sound beam d) A function that is performed before the echo data are stored in memory e) Any function that changes the quality of the ultrasound image |
d) A function that is performed before the echo data are stored in memory Any function that occurs after this point is referred to as postprocessing. As notes elsewhere, the easiest way to distinguish pre and postprocessing functions is this: If it can't be performed on a frozen image, it is preprocessing; if it can be performed on a frozen image, it is postprocessing. |
|
|
Increasing the dynamic range setting affects the ultrasound image by: a) Increasing image brightness b) Decreasing image contrast c) Improving spatial resolution d) Increasing rejection of low-level echoes e) Improving signal-to-noise ratio |
b) Decreasing image contrast As dynamic range is increased, small changes in echo amplitude result in assignment to different shades of gray. Echo amplitudes are reassigned to a larger dynamic range. Some of the amplitudes may have been assigned to zero when the dynamic range was set to a lower value. By increasing the dynamic range, these echo amplitudes are now assigned a low level of gray. This results in display of more information, but reduces the overall contrast of the image. |
|
|
When you adjust the TGC, what component of the ultrasound system implements the changes? a) Pulser b) Receiver c) Monitor d) Scan converter e) Clock |
b) Receiver |
|
|
A typical value for the duty factor in diagnostic sonographic imaging is: b) 50-75% c) 25-45% d) 5-20% e) 0.1-1% |
e) 0.1-1% Duty factor is the time that the sound beam is actually on. With pulsed-wave imaging, the fraction of the time the sound is on is quite low because the transducer is listening most of the time. |
|
|
Pulse repetition period (PRP) is the inverse of: a) Duty factor b) Pulse repetition frequency c) Frame rate d) Pulse duration e) Spatial pulse length |
b) Pulse repetition frequency PRP is the time between pulses, whereas PRF is the number of pulses per second. |
|
|
What system component determines the pulse repetition frequency? a) Pulser b) Receiver c) Memory d) Display e) Scan converter |
a) Pulser Pulser produces electric voltages that drive the transducer. The rate at which the voltages are applied determines PRF. |
|
|
In ultrasound systems, the range equation is used to determine which of the following? a) Reflector amplitude b) Reflector frequency c) Reflector direction d) Reflector depth e) Reflector size |
d) Reflector depth The range equation can be stated as: d=1/2ct d=depth c=speed of sound in tissue t=round trip travel time |
|
|
You have increased the output power by 10dB. The signal intensity has: a) Doubled b) Tripled c) Quadrupled d) Increased by a factor of 10 e) Increased by a factor of 100 |
d) Increased by a factor of 10 |
|
|
What is the purpose of the preamplification of the incoming signal that occurs in the transducer assembly? a) To decrease the dynamic range of the signal b) To increase echo voltages before noise is induced through the cable c) To reduce sensitivity to side lobes d) To reduce acoustic impedance mismatch between the tissue and the transducer e) To compensate for attenuation of the beam with depth |
b) To increase echo voltages before noise is induced through the cable By amplifying the signal before it passes through the transducer cable, amplification of electronic noise is reduced. This improves the signal-to-noise ratio and the sensitivity of the receiver. |
|
|
What function of the receiver converts electrical signals from radiofrequency to video form? a) Amplification b) Compensation c) Compression d) Demodulation e) Rejection |
d) Demodulation
Demodulation is accomplished by rectification and smoothing (filtering). Demodulation may also be called amplitude detection or envelope detection. |
|
|
What component of the ultrasound system converts the electric energy provided by the pulser into acoustic pulses transmitted into the patient?
a) Receiver b) Scan converter c) Memory d) Display e) Transducer |
e) Transducer The function of the transducer is to convert electric energy into mechanical vibrations sound energy) for transmission into the patient. Conversely, when the reflected sound energy is received by the transducer, it converts it into electric energy. |
|
|
The incoming raw echo signals must be compressed into a smaller dynamic range because: a) A wide dynamic range results in increased display of electronic noise b) A wide dynamic range does not allow differentiation between echoes arriving from different paths c) The display cannot accommodate the wide dynamic range of the incoming signals d) The existing wide dynamic range significantly slows the frame rate e) A wide dynamic range compromises spatial resolution |
c) The display cannot accommodate the wide dynamic range of incoming signals
Because the dynamic range of the system electronics and display is less than that of the raw echo data, it must be compressed into a usable range. |
|
|
Which of the following is NOT a function of the receiver? a) Amplification b) RF to video conversion c) Demodulation d) Dynamic aperture e) Compression |
d) Dynamic aperture Dynamic aperture is a function of the beam former and pulser. It is performed during transmit and receive beam forming. |
|
|
What system function is limited by the speed of sound in tissue? a) Demodulation b) PRF c) Voltage amplitude d) Rectification e) Time gain compression |
b) PRF The maximum usable PRF is limited by the speed of sound in tissue because there must be enough time between the pulses for the ultrasound to travel to and back from the reflector. As the PRF is increased, there is less "listening" time between the pulses and hence less travel time for the echoes. If echoes from deeper structures are received from the first pulse after a second pulse has been transmitted, range ambiguity results. In other words, the system cannot accurately detect the depth of the returning echo and will assume it arrived from the most recently transmitted pulse. This will cause the reflector to be misplaced axially on the image in a position relating to a more superficial structure. If sound traveled faster in tissue, the maximum PRF could be increased. Unfortunately, the speed of sound in tissue is determined by the medium through which it travels and cannot be adjusted by the operator or the system. |
|
|
What control should you adjust to modify the image if the attenuation coefficient of the tissue is very high? a) Dynamic range b) Rejection c) Threshold d) Compensation e) Compression |
d) Compensation Compensation is generally referred to as TGC or DGC. It is used to increase amplification to account for the effects of attenuation. |
|
|
YoU mAdE cHaNgEs tO tHe FoLLoWiNg CoNtRoLs DuRiNg a SoNoGrAm. wHiCh aDjUsTmEnT iNcReAsEd DuTy FaCtOr? a) iNcReAsInG rEcEiVeR gAiN b) iNcReAsInG oUtPuT pOwEr c) iNcReAsInG PuLsE RePiTiTioN fReQuEnCy d) iNcReAsInG sCaNNiNg TiMe e) iNcReAsInG TiMe gAiN cOnTroL |
c) iNcReAsInG PuLsE RePiTiTioN fReQuEnCy The PRF is the number of pulses emitted in one second. The duty factor is the percentage of time that the ultrasound is being transmitted. As the PRF increases, the percentage of time the ultrasound is "on" is increased. None of the other choices will increase the amount of time the sound is actually "on." |
|
|
What is the advantage of using Write zoom instead of Read zoom magnification? a) Write zoom always provides a higher frame rate than Read zoom b) Write zoom allows you to select a location in the image, whereas Read zoom must be applied to only the center of the image c) Write zoom produces the display of electronic noise and side lobes because it is performed in the memory component of the instrument d) Write zoom provides greater dynamic range than Read zoom e) Write zoom provides better spatial resolution than Read zoom |
e) Write zoom provides better spatial resolution than Read zoom This is because the entire image memory can be used for storing data for the image. |
|
|
How is reflector depth determined with pulse-echo ultrasound? a) Echo amplitude b) Echo dynamic range c) Echo frequency d) Echo arrival time e) Echo phase |
d) Echo arrival time Reflector depth is determined by measuring the elapsed time between the transmitted pulse and the reception of the echo. |
|
|
What effect will you detect in the image if you increase the threshold control? a) Increased image brightness b) Decreased image brightness c) Decreased appearance of weak echo signals d) Increased appearance of strong echo signals e) Decreased appearance of strong echo signals |
d) Decreased appearance of weak echo signals "Threshold" is another name for the reject control. It is used to reduce the display of weak echo signals that most likely arise from electronic noise. Increasing the threshold reduces the display of weak signals. |
|
|
What can you do to improve the temporal resolution while scanning? a) Increase the number of focal zones b) Increase the depth c) Increase the sector width d) Decrease the acoustic scan line density e) Decrease the acoustic power output |
d) Decrease the acoustic scan line density Decreasing the number of acoustic scan lines that make up an image decreases the time required to create the image. This results in increased frame rate. |
|
|
The number of images displayed per second in real-time imaging is termed the: a) PRF b) PRP c) Frame rate d) Pulse duration e) Pulse length |
c) Frame rate |
|
|
Which scanning mode does NOT rely on the principle of echo ranging to determine interface location? a) M-mode b) Pulsed-wave Doppler c) Static B-mode d) Transmission e) A-mode |
d) Transmission More Q&A Information This question belongs to the following ARDMS exam topic: |
|
|
Which display mode may be used to calculate distance measurements? a) A-mode b) B-mode c) M-mode d) B and C only e) A, B, and C |
e) A, B, and C |
|
|
Which of the following best describes M-mode? a) Presentation of reflector amplitudes along multiple lines of sight b) Two-dimensional gray-scale image c) Movement of a single structure along multiple lines of sight d) Depth of reflectors along a single line of sight vs. time e) Frequency shift of moving reflectors along a single line of sight |
d) Depth of reflectors along a single line of sight vs. time |
|
|
Which is an assumption of sonographic imaging that determines how detected echoes are mapped in the image? a) Sound waves travel along curved paths b) Velocity is a constant 333 m/s c) Echoes originate from the most recently transmitted pulse d) Large structures yield a high brightness level on the display e) Media with varying propagation speeds alter the travel time of the sound pulse |
c) Echoes originate from the most recently transmitted pulse It is always assumed that received echoes originate from the most recently transmitted pulse. After a pulse is generated, time is counted for each received echo until generation of the next pulse, which starts the time count all over again. |
|
|
What physical concept allows us to determine the location of an interface by measuring the elapsed time between the transmitted pulsed ultrasound wave and the detected echo from the interface? a) Huygen's principle b) Echo ranging c) Snell's law d) Doppler effect e) None of the above |
b) Echo ranging Echo ranging involves use of the range equation with pulsed-wave imaging to determine reflector depth. |
|
|
The elapsed time between the transmitted pulse and the detected echo is 26 microseconds. How far is the interface from the transducer? a) 1 cm b) 2 cm c) 3 cm d) 4 cm e) 5 cm |
b) 2 cm Ultrasound pulse takes a total time of 13 microseconds to travel to a reflector that is 1cm deep and then 1 cm back again to the transducer. |
|
|
During a sonographic exam, you adjusted the following controls. Which one was most likely to have affected the frame rate? a) Amplification b) Transmit power c) Scan depth d) TGC e) Compression |
c) Scan depth As scanning depth is increased, the system must decrease the PRF to avoid range ambiguity. In other words, it must increase the time between pulses to account for the additional time it takes the ultrasound pulse to travel to and from a reflector at the bottom of the field of view. As PRF decreases, frame rate decreases. It takes longer to fire the required number of pulses to create the image because the time interval between pulses is greater. |
|
|
Electronic steering is most commonly applied to which of the following real-time transducers? a) Annular array b) Sequential linear array c) Mechanical sector d) Phased array e) Segmental linear array |
d) Phased array |
|
|
How many lines of sight are sampled and displayed on the monitor in A-mode? a) 1 b) 2 c) 10 d) 256 e) 525 |
a) 1 |
|
|
While performing an obstetrical sonogram, you wish to increase the frame rate to evaluate the fetal heart. What should you do? a) Increase scan line density b) Increase the number of focal zones c) Decrease the sector width d) Decrease the system PRF e) All of the above |
c) Decrease the sector width |
|
|
Blood vessels usually appear anechoic on B-mode imaging because: a) They are empty b) The red blood cells cannot reflect the sound beam c) The red blood cells absorb the sound d) The reflection from the red blood cells is too weak to be displayed e) The red blood cells are moving too fast to produce a reflection |
d) The reflection from the red blood cells is too weak to be displayed |
|
Which echo amplitude in the following illustration would produce the brightest dot on a B-mode display? |
E - The brightness of the dot on the B-mode images is directly related to amplitude of the reflected signal. |
|
|
Which of the following is NOT a limitation of M-mode scanning? a) Information is obtained along only one line of sight b) Motion lateral to the transducer is not displayed c) Motion axial to the transducer is not displayed d) The two-dimensional shape of a structure is not shown e) All of the above are limitations of M-mode |
b) Motion lateral to the transducer is not displayed With M-mode, motion lateral to the transducer is not displayed, but motion axial to the transducer is displayed. |
|
|
Which action would decrease frame rate? a) Increasing pulse repetition frequency b) Increasing acoustic scan line density c) Decreasing sector width d) Decreasing the number of focal zones e) Decreasing image depth |
b) Increasing acoustic scan line density Temporal resolution is determined by the frame rate. Several factors affect the frame rate. As the density of the acoustic scan lines increases, lateral resolution increases but frame rate decreases because it takes additional time to perform the pulse-listen sequences for each new line of sight. All of the other answer choices would result in increased temporal resolution (increased frame rate). |
|
|
In order for distance measurements to be accurate in an ultrasound tissue phantom, the phantom sound propagation speed must be: a) 13 µs/cm b) 1.54 m/s c) 1540 m/s d) 1/2 the speed of sound in tissue e) 2x the speed of sound in tissue |
c) 1540 m/s |
|
|
You have expanded the image sector width to improve visualization of a large mass. What can you do to maintain the same temporal resolution you had before your adjustment? a) Increase the digitization bit depth b) Increase the number of scan lines c) Decrease the number of pixels in the image matrix d) Decrease the number of focal zones e) Decrease the PRF |
d) Decrease the number of focal zones On each line of sight, a pulse-echo/sequence is required for each focal zone selected. So as the number of focal zones increases, the frame rate decreases. |
|
|
What information is present in the M-mode display? a) Time, motion pattern, and amplitude b) Amplitude, frequency, and time c) Motion pattern and frequency d) Time, motion pattern, and frequency e) Bandwidth, amplitude, frequency, time, and motion pattern |
a) Time, motion pattern, and amplitude |
|
|
With A-mode, the strength of the echo signal is represented by: a) The brightness of the dot b) The brightness of the spike c) The distance between two spikes d) The distance between two dots e) The height of the spike |
e) The height of the spike |
|
|
What information is present in the A-mode display? a) Frequency bandwidth, amplitude, and reflector distance b) Time, amplitude, and motion pattern c) Amplitude and reflector distance d) Time, motion pattern, reflector distance, and frequency bandwidth e) Frequency shift, amplitude, and reflector distance |
c) Amplitude and reflector distance |
|
|
An M-mode display is most commonly used for what type of ultrasound imaging? a) Small parts b) Abdominal c) Cardiac d) Vascular e) Ophthalmology |
c) Cardiac |
|
|
A-mode display is most commonly used for what type of ultrasound imaging? a) Small parts b) Abdominal c) Cardiac d) Vascular e) Ophthalmologic |
e) Ophthalmologic |
|
|
With an A-mode display, the internal contents of a simple cyst will appear as: a) An area with very dark shades of gray b) An area with rapidly moving spikes c) An area with tall spikes surrounded on each end with areas absent of spikes d) An area with no spikes e) An area with multiple tiny spikes |
d) An area with no spikes On the A-mode display, the height of the spike is directly related to the amplitude of the reflector. Because no signals are reflected from the internal contents of a simple cyst, the depth corresponding to the inside of the cyst will be absent of spikes. The walls of the cyst, however, are highly reflective and will be represented by a tall spike. |
|
|
What is an advantage of a water-path scanner? a) Near-field reverberations are reduced b) Penetration is increased c) Temporal resolution is improved d) Axial resolution is improved e) Slice thickness is reduced |
a) Near-field reverberations are reduced |
|
|
What is a disadvantage of a water-path scanner? a) It reduces axial resolution b) The beam width perpendicular to the image plane is increased, resulting in poor elevational resolution c) Bubbles in the fluid can inhibit sound transmission into the body d) It is useful only with very low frequencies e) The fluid path increases the mechanical index |
c) Bubbles in the fluid can inhibit sound transmission into the body Although water path scanners reduce the reverberation from shallow structures, they require vigorous maintenance to keep the fluid path completely filled at all times. If the fluid path is only partially filled, air within bubbles can become trapped between the transducer and the probe surface, reflecting the sound before it can enter the body. |
|
|
You are manipulating a volume dataset that was previously obtained on your patient. What is the maximum number of imaging planes that can be obtained from the dataset? a) One b) Ten c) 100 d) 1,000 e) There is no limit |
e) There is no limit |
|
|
While performing a sonographic exam, you increase both imaging depth and scan line density. These adjustments produce the following result: a) Reduced contrast resolution b) Reduced temporal resolution c) Improved axial resolution d) Reduced lateral resolution e) All of the above |
b) Reduced temporal resolution Increasing the imaging depth reduces the frame rate because teh system must allow more time between pulses for the arrival of echoes from deeper structures. Increasing the scan line density reduces the frame rate by requiring more pulse-listen sequences to create each image. Decreasing the frame rate reduces temporal resolution. Contrast resolution and axial resolution are not affected by these changes. Increasing the scan line density will improve lateral resolution. |
|
|
What is the advantage of using a 3D/4D transducer with an automated sweep compared to a traditional transducer with a freehand sweep? a) Measurement accuracy b) Spatial resolution c) Contrast resolution d) Larger field of view e) Greater scanning flexibility |
a) Measurement accuracy A volume dataset may be obtained by a freehand sweep of the probe over the anatomy or by an automated sweep of the transducer within the probe. Automated 3D sweeps can be obtained with specially designed mechanical or electronic transducers. One advantage of the automated method is that measurements can be accurately obtained because the distance of the sweep is known. |
|
|
Which of the following does not affect the time required to create one image frame? a) Number of transmit focal zones b) Number of acoustic scan lines c) Image depth setting d) Speed of sound in tissue e) Transducer aperture |
e) Transducer aperture The time required to create one image is determined by all of the answer choices except transducer aperture. The aperture in an array is the number of active elements. |
|
|
Increasing the number of acoustic scan lines in one frame improves which of the following? a) Temporal resolution b) Axial resolution c) Elevational resolution d) Lateral resolution e) Contrast resolution |
d) Lateral resolution As the number of lines in one frame increases, the distance between lines decreases. Because structures that are smaller in the lateral dimension than the distance between the lines of sight cannot be detected, reducing this distance improves lateral resolution. Increasing the number of lines of sight decreases temporal resolution. The other types of resolution are not affected. |
|
|
You have decreased the image sector width. Which of the following will most likely change as a result of this adjustment? a) Frame rate b) Axial resolution c) Elevational resolution d) Dynamic range e) Bandwidth |
a) Frame rate In general, when the sector angle is decreased, the number of scan lines is reduced. This increases frame rate. |
|
|
Which of the following ultrasound examinations would require the highest frame rate? b) Abdominal c) Pelvic d) Vascular e) Cardiac |
e) Cardiac Since the heart is a rapidly moving structure, high frame rates are required to assess it accurately... and we're better than everyone else. |
|
|
Which of the following adjustments would NOT decrease frame rate? a) Increasing the number of transmit focal zones b) Increasing scanning depth c) Increasing receiver gain d) Increasing scan line density e) Increasing sector width |
c) Increasing the receiver gain |
|
|
When you increase the scanning depth, which of the following is automatically decreased by the system to avoid range ambiguity? a) Number of focal zones b) Sector width c) PRF d) PRP e) Pulse duration |
c) PRF The system automatically adjusts the PRF downward when the scanning depth is increased to avoid range ambiguity. |
|
|
You are scanning an interface with a high acoustic impedance mismatch. How will this be displayed on the B-mode image? a) A tall spike b) A small spike c) A bright dot d) A dark dot e) The height of the spike or brightness of the dot is not affected by acoustic impedance mismatch |
c) A bright dot
B-mode stands for brightness mode. Echo signals are assigned a gray-scale level according to the amplitude of the reflected signal. Higher amplitude signals are assigned brighter gray-scale dots. An interface with a high acoustic impedance mismatch will produce a large, high amplitude reflection. |
|
|
The "A" in A-mode stands for: a) Average b) Attenuation c) Aperture d) Amplitude e) Acoustic f) April |
d) Amplitude Because amplitude. |
|
|
The "M" in M-mode stands for: a) Motion b) Magnetic c) Megahertz d) Manual e) Maximum f) Mach g) Mark h) McDavid |
a) Motion Because in the ocean. |
|
|
What component is necessary for a real-time B-mode scanner but is not present in an A-mode scanner? a) Clock b) Transmitter c) Transducer d) Scan converter e) Receiver |
d) Scan converter |
|
|
What system control converts the numbers stored in memory to proportional voltages that control the brightness on a CRT monitor? a) Analog to digital converter b) Digital to analog converter c) CRT (cathode ray tube) d) Reveiver e) Pulser |
b) Digital to analog converter For display, the numbers stored in memory must be converted to proportional voltages to drive the brightness of the monitor. Monitors are more likely to be digital in modern ultrasound equipment. |
|
|
A digital scan converter is another name for what system component? a) Pulser b) Reveiver c) Image memory d) Analog to digital converter e) Beam former |
c) Image memory |
|
|
What control allows the user to freeze and then scroll back through the most recently acquired image frames? b) Read zoom c) Writer zoom d) Archive e) Preprocessing |
a) Cineloop |
|
|
A group of 8 bits is called: b) Kilobyte c) Pixel d) Byte e) Matrix |
d) Byte |
|
|
Where are images stored in the ultrasound computer? a) Pulser b) Receiver c) Beam former d) Display e) Scan converter |
e) Scan converter |
|
|
What is the maximum number of shades of gray in an 8-bit digital scan converter? b) 32 c) 64 d) 128 e) 256 |
e) 256 |
|
|
The spatial resolution of the scan converter is determined by: a) Number of pixels in the scan converter matrix b) Number of bits per pixel c) The post-processing settings d) Brightness and contrast settings of the monitor e) Interpolation scheme |
a) Number of pixels in the scan converter matrix A matrix of 512x512 pixels is capable of much better spatial resolution than a similarly sized matrix containing only 64x64 pixels. In the latter example, the image would appear blocky with discrete square-shaped segments. Image resolution would be degraded. |
|
|
What system component is responsible for transmit focusing? a) Receiver b) Monitor c) Beam former d) Preprocessing e) System clock |
c) Beam former Specifically, the transmit beam former, which introduces time delays into the excitation pulse sequence applied to the elements. |
|
|
How many levels of information can a single bit represent? b) 2 c) 4 d) 8 e) 16 |
b) 2 A single bit can represent only 2 values, on and off. The earliest ultrasound system only showed 1 bit of information. They were referred to as bistable. Images were displayed with only two shades -- black or white. Obviously, the amount of information that could be obtained with such systems was quite limited compared to today's instruments. |
|
|
The picture elements in a scan converter matrix are termed: b) Binary numerals c) Bits d) Pixels e) Bytes |
d) Pixels |
|
|
Digital to analog conversion of the ultrasound signal must occur at what part of the imaging process? b) Between the beam former and the transducer c) Between the receiver and the scan converter d) Between the scan converter and the display e) Digital to analog conversion does not occur in the ultrasound system |
d) Between the scan converter and the display |
|
|
In the scan converter, interpolation is performed to: a) Amplify the reflected signal in comparison to the background noise b) Decrease the dynamic range to a level that can be handled by the monitor c) Amplify weak echo signals from deep structures to compensate for beam attenuation d) Fill in the empty pixels that occur between acoustic scan lines e) Increase the number of shades of gray in the resultant image |
d) Fill in the empty pixels that occur between acoustic scan lines Interpolation is necessary because there is not data available for all pixels in the scan converter matrix. As the line density in the ultrasound image is decreased, more interpolation becomes necessary to fill in the empty spaces. Although there are a lot of different interpolation schemes used by different manufactures, in general, the empty pixel is filled in with a value that is averaged between adjacent pixels. |
|
|
Without interpolation, which of the following would best describe the resultant B-mode image? a) Very weak echoes in the far field compared to the near field b) Poor differentiation between the ultrasound signal and the noise floor c) Saturation of the white shades on the ultrasound monitor d) A series of scan lines with blank data between the lines e) A bistable image |
d) A series of scan lines with blank data between the lines Very early real-time systems created images that looked like jail bars, in which the scan lines were displayed but the space between each scan line was left blank. Today, interpolation of the data is used to fill in the blank spaces to make the image appear smooth and continuous, even though it is still created from the combination of individual scan lines. |
|
|
What three colors are used on a color monitor to produce the range of available colors? a) Red, purple, yellow b) Yellow, green, blue c) Blue, yellow, red d) Red, green, blue e) Blue, white, red |
d) Red, green, blue These three colors are commonly referred as the RGB signal. |
|
|
When you "freeze" the ultrasound image, where is the echo information stored? a) Transducer b) Scan converter c) Cable d) Beam former e) Receiver |
b) Scan converter The scan converter is the digital memory of the system. |
|
|
What type of resolution is determined by the number of pixels in the scan converter? a) Temporal b) Contrast c) Spatial d) Elevational e) All of the above |
c) Spatial As the number of pixels increases, the spatial resolution of the image improves. The spatial resolution can be no better than that obtained from the beam forming, but it can be worse. |
|
|
Which of the following is associated with improper adjustment of the brightness and contrast on the video monitor? a) The spatial resolution of the resultant image will be degraded b) The operator will likely overgain or undergain the image c) The temporal resolution will be reduced d) The flicker rate of the video monitor will be increased e) The penetration of the transducer will be reduced |
b) The operator will likely overgain or undergain the image The amount of gain the operator applies is subjectively determined by the appearance of the image brightness. If the monitor is set too dark, the operator may overgain the image to compensate for the dark monitor. If the monitor is too bright, the operator might undergain the image to compensate. |
|
|
What can you improve by changing gray-scale map? a) Axial resolution b) Lateral resolution c) Contrast resolution d) Elevational resolution e) Temporal resolution |
c) Contrast resolution |
|
|
Which of the following describes an analog signal? a) Discrete values b) Fixed steps between values c) Continuous variation of the signal is possible d) Levels are determined by bits e) No analog signals exist in modern instruments |
c) Continuous variation of the signal is possible An analog signal does not have discrete steps. Its values may vary continuously between a minimum and maximum point. Digital devices have discrete values that have fixed steps between values. Bits determine the levels in a digital system. |
|
|
What is the order in which the signal travels in the ultrasound system? a) Transducer, receiver, display, scan converter b) Scan converter, transducer, receiver, display c) Scan converter, receiver, transducer, display d) Transducer, receiver, scan converter, display e) Receiver, transducer, scan converter, display |
d) Transducer, receiver, scan converter, display |
|
|
Of the following, which is the best choice to help you demonstrate tissue boundaries that are not perpendicular to the sound beam? a) Speckle-reduding algorithm b) Spatial compounding c) Persistence d) Panoramic imaging e) Time gain compensation |
b) Spatial compounding Spacial compounding is a method in which the sound beam is steered in multiple directions by employing time delays. The images from all of the steered frames are averaged together to produce one image for the display. The number of steered beams is usually chosen by the operator, but varies from 3 to 9 or more. The final composite image demonstrates tissue boundaries better than a single unsteered image because more of the boundary is interrogated at angles approaching perpendicular incidence. |
|
|
You want to use 3D imaging to display an anatomic structure because 3D has the following advantage over 2D imaging: a) Higher frame rates b) Better spatial resolution c) Ability to display image planes impossible to obtain with 2D imaging d) Ability to display orthogonal plans simultaneously e) C and D |
d) C and D |
|
|
What is meant by the term 3D imaging in sonography? a) 3D imaging with the addition of time b) 3D imaging with rendering c) 3D imaging with transparent views d) 3D imaging with tomographic views e) 3D imaging with rotational movie |
a) 3D imaging with the addition of time A 3D sonographic image that is real-time is termed 4D. The fourth dimension is time. |
|
In this image of an artery there is calcification with a dark vertical band extending beyond it (arrow). Which explanation best describes the etiology of the dark band? a) Propagation speed error at the vessel wall interface b) Reduction in signal amplitude in tissue distal to a highly attenuation or reflecting object c) Refraction due to oblique incidence at the plaque interface d) Range ambiguity due to high PRF setting e) Comet tail artifact due to calcification in plaque |
b) Reduction in signal amplitude in tissue distal to a highly attenuation or reflecting object |
|
Which term below most correctly describes this Doppler wave form? a) Aliasing b) Spectral mirroring c) Spectral broadening due to sample volume size d) Reverberation e) Bidirectional flow |
b) Spectral mirroring |
|
What should be done to improve this Doppler wave form? a) Change the Doppler angle b) Decrease the Doppler gain c) Increase the PRF d) Reposition the sample volume e) Decrease the sample volume length |
a) Change the Doppler angle |
|
What is the source of the echoes depicted by the arrows in this image of the kidney? a) Side lobes b) Grating lobes c) Refraction d) Reverberation e) Multipath reflections |
d) Reverberation |
|
What is another name for the hyperechoic artifact distal to a fluid structure? a) Refraction b) Shadowing c) Speckle d) Grating lobe e) Enhancement |
e) Enhancement |
|
These B-mode images of the common carotid artery show a graphic overlay indicating the number of lines of sight used to acquire each frame of information. No other system parameter was adjusted. Which statement below is true comparing image A to image B? a) Image A has a frame rate higher than image B b) Image A has a better lateral resolution than image B c) Image A has a better axial resolution than image B d) The temporal resolution is better in image A than in image B e) The PRF in image A is lower than that in image B |
b) Image A has a better lateral resolution than image B |
|
In these images, what technique is used to fill in the empty data between the scan lines? b) Interpolation c) Dynamic receive d) Subdicing e) Dynamic damping |
b) Interpolation |
|
|
You are imaging a 3D dataset that has anisotropic resolution. What does this mean? a) Spatial resolution is better than temporal resolution b) Spatial resolution is equal in all dimensions c) Contrast resolution is superior to spatial resolution d) Unequal resolution is present between imaging planes e) Elevational resolution and contrast resolution are the same |
d) Unequal resolution is present between imaging planes Isotropic resolution means that the spatial resolution is equal in all dimensions or imaging planes. Anisotropic resolution is the opposite of this. |
|
The following two sagittal images of an artery were obtained with different transducers. What type of resolution is limiting visualization of teh arterial lumen in the image on the left? b) Lateral c) Temporal d) Slice thickness e) Contrast |
d) Slice thickness The artery on the left is not well demonstrated because the slice thickness of the beam is too great at that scanning depth. If the beam is wider than the vessel, tissue on either side will send back reflections, resulting in fill-in of the fluid structure. The right image shows the radial artery with an anechoic lumen. This can be seen because the slice thickness is no wider than the vessel with this transducer. The transducer used to obtain this image is a matrix array in which there are multiple rows of elements along both the width and the length of the transducer. This arrangement allows for electronic focusing in both dimensions, resulting in a thinner beam slice. |
|
|
You are imaging a fluid-filled structure that has equidistant horizontal bands appearing in the near field. The bands have decreasing brightness with depth. What artifact are you imaging? a) Slice thickness b) Side lobes c) Reverberation d) Comet tail e) Ring down |
c) Reverberation |
|
|
The waveform you obtained from an arterial stenosis demonstrates aliasing. If you increase the PRF to eliminate the aliasing, what artifact could be introduced? a) Multipath reflections b) Spectrum mirror image c) Propagation speed error d) Range ambiguity e) Refraction |
d) Range ambiguity If pulses are transmitted very rapidly (high PRF), it becomes increasingly likely that an echo from within the Doppler sample volume will arrive at the transducer after another pulse has been transmitted along the Doppler beam line. Because the system assumes that all reflections are related to the most recently transmitted pulse, the echo will be misplaced closer to the transducer face than its actual location. This is because the system will think it took much less time to arrive than it actually did. This phenomenon is called range ambiguity. |
|
|
You have obtained an ultrasound image that demonstrates refraction of the sound beam. This artifact might be manifested as: a) Axial displacement of a reflector b) Enhancement distal to a reflector c) Lateral displacement of the displayed position of a reflector d) Multiple images of a single reflector e) Increased brightness of a reflector |
c) Lateral displacement of the displayed position of a reflector Refraction is bending of the sound beam. Because the system must assume that the ultrasound is coursing straight from the transducer face, refraction results in a misplacement of the reflectors laterally. |
|
|
Which of the following conditions will result in aliasing of the Doppler frequency shift using continuous-wave Doppler? a) PRF 10 kHz, frequency shift 4 kHz b) PRF 12 kHz, frequency shift 8 kHz c) PRF 5 kHz, frequency shift 2.3 kHz d) PRF 8 kHz, frequency shift 5 kHz e) None of the above |
e) None of the above Aliasing does not occur with CW Doppler. Aliasing of the Doppler spectrum is an artifact that occurs with PW Doppler when the frequency shift is greater than 1/2 the Doppler PRF. |
|
|
You obtained a 3D sweep in an axial plane and are viewing it in a multiplanar display. What orthogonal planes will be displayed? b) Transverse and coronal c) Transverse and sagittal d) Oblique planes at 90 degrees e) Oblique planes at 60 degrees |
a) Coronal and sagittal |
|
|
You are using a transducer that produces a beam with a very wide slice thickness. Which of the following problems are you most likely to encounter as a result? a) Increased near field reverberation in the fluid structures b) Increased side lobes c) Decreased penetration d) Partial volume artifact e) Decreased frame rate |
d) Partial volume artifact Partial volume artifact is also known as slice thickness artifact. It occurs when the slice thickness is wider than the structure being imaged. In other words, if you are imaging a small vessel in a sagittal plane, it may appear to contain echoes. Yet when you turn transverse to the vessel, you see that it is completely free of echoes. The source of the echoes in the sagittal plane is the slice thickness artifact. The beam is wider than the vessel. Tissue on both sides of the vessel refelcts signals from that depth to the transducer. These echoes are placed at that depth on the image, artifactually filling in the vessel. |
|
|
Which technology would be most helpful to obtain accurate anatomic volume measurements? a) 2D imaging b) 3D imaging c) Color Doppler imaging d) Harmonic imaging e) Compound imaging |
b) 3D imaging 3D imaging is helpful for measuring anatomic volumes, especially those that are irregularly shaped. |
|
|
You may observe mirror image artifact with which imaging mode? a) B-mode b) Spectral Doppler c) Color Doppler d) Power Doppler e) All of the above |
e) All of the above |
