Mark to Crystal Qs Flashcards
(150 cards)
- Which choice best completes the sentence? The primary function of a phototimer is to:
a. provide a consistent exposure by compensating for variations in thickness of patients.
b. compensate for unstable high voltage electrical supply.
c. limit the need for manual collimation.
d. provide a consistent exposure by compensating for variations in film-screen combinations.
e. Prevent excessive skin doses
a. provide a consistent exposure by compensating for variations in thickness of patients.
Sharpness is the ability of the x-ray film/image to define an edge. Which one of the following statements concerning film sharpness is true?
a. An unsharp edge can be difficult to see if contrast is high, but a sharp edge is easily seen if contrast is low
b. Longer exposure times will minimize motion unsharpness
c. The edges of round or oval shaped objects will generally be better defined than squared or rectangular objects
d. The use of a small focal spot will help maximize edge sharpness by minimizing the size of the penumbra
e. The use of intensifying screens improves image sharpness
d. The use of a small focal spot will help maximize edge sharpness by minimizing the size of the penumbra
Resolution (as it pertains to a radiographic image) is the ability to record separate images of small objects that are placed very closely together. Which one of the following statements regarding resolution is true?
a. A system that can resolve 4 line pairs per mm has better sharpness than a system that can resolve 6 line pairs per mm.
b. If an image has a resolution of 4 line pairs per mm, that means it can differentiate 4 lead strips separated by 4 radiolucent spacers that are all 1/4 mm apart.
c. If an image has a resolution of 4 line pairs per mm, that means it can differentiate 4 lead strips separated by 4 radiolucent spacers that are all 1/8 mm apart.
d. A system that can resolve 4 line pairs per mm has better resolution than a system that can resolve 6 line pairs per mm.
e. Resolution is unrelated to sharpness
c. If an image has a resolution of 4 line pairs per mm, that means it can differentiate 4 lead strips separated by 4 radiolucent spacers that are all 1/8 mm apart.
Transformers have as their primary function:
a. Converting alternating current into direct current
b. Converting direct current into alternating current
c. Changing an input voltage into a different output voltage
d. Terminating x-ray exposure after a defined output has been reached
e. Regulating variations in mains voltage supply
c. Changing an input voltage into a different output voltage
- Which of the following statements is true regarding compensation filtration?
a. Compensation filtration is due primarily to attenuation by housing oil.
b. Compensation filtration delivers a more uniform x-ray exposure across the field.
c. Compensation filtration results in increased patient dose.
d. Compensation filters are made from beryllium in standard diagnostic machines
e. Compensation filtration is used to uniformly increase the HVL of the x-ray beam.
b. Compensation filtration delivers a more uniform x-ray exposure across the field.
- Which of the following statements is true?
a. The frequency and wavelength of electromagnetic radiation are inversely proportional.
b. The speed of electromagnetic radiation waves is variable depending on energy.
c. Gamma radiation does not exhibit particulate properties.
d. The wavelength of x-rays is longer than that of radiant heat waves.
e. The wavelength of gamma rays is longer than that of x-rays
a. The frequency and wavelength of electromagnetic radiation are inversely proportional.
- Which one of the following statements concerning film processing is true?
a. Development can be defined as the chemical process that amplifies the latent image by a factor of ten to form a visible silver pattern on a film.
b. In the development stage, silver ions are oxidized (electron is removed) by the developer chemical which changes it to black metallic silver.
c. Examples of typical fixing chemicals include hydroquinone, phenidone and metol.
d. Antifoggant chemicals are added to the developer solutions in automatic processors to limit development of unexposed silver ions.
e. Development at 15oC takes less than 4 minutes to produce a diagnostic film.
d. Antifoggant chemicals are added to the developer solutions in automatic processors to limit development of unexposed silver ions.
- An image intensifier tube is used in fluoroscopic equipment. Which one of the following statements concerning an image intensifier is correct?
a. Gadolinium oxysulphide is chosen as the photocathode as it can be grown and deposited in thin needle like orientation which minimizes light scatter
b. An electrostatic focusing lens is used to focus the electron beam arising from the input phosphor onto the output fluorescent screen.
c. The function of the input phosphor screen is to collect incoming x-ray photons, initially convert them to light photons, which are then converted to photoelectrons by the photocathode
d. The image on the output phosphor is less bright than the input phosphor owing to the fact that many light photons are absorbed or lost as they pass from the input phosphor to the output phosphor.
e. Use of an image intensifier results in higher radiation doses to the patient than direct fluoroscopy
c. The function of the input phosphor screen is to collect incoming x-ray photons, initially convert them to light photons, which are then converted to photoelectrons by the photocathode
- Compared to a 16° anode angle, an 8° anode angle provides a __________________ effective focal spot, and at the same time _______________ field coverage.
a. smaller, smaller
b. smaller, larger
c. smaller, no change in
d. larger, larger
e. larger, no change in
a. smaller, smaller
- Which one of the following statements concerning the heel effect is true?
a. The intensity of the x-ray beam is decreased on the cathode side of the x-ray tube
b. The cathode itself may absorb a portion of the x-ray energy, thus decreasing the intensity of the beam on the cathode side of the tube
c. The heel effect is most obvious using small film size
d. The heel effect is more pronounced at shorter focal-spot to film distances
e. Thicker parts of the animal should be directed towards the anode side of the x-ray tube
d. The heel effect is more pronounced at shorter focal-spot to film distances
- The main purpose for the second set of lead shutters in a variable aperture collimator is to:
a. minimise the effect of errors in mirror angle
b. minimise the number of non-diagnostic energy x-rays
c. minimise the amount of scatter radiation
d. minimise penumbra
e. minimise the skin dose
d. minimise penumbra
- Which of the following statements concerning Bremsstrahlung interactions is true?
a. The maximum energy of the x-ray beam produced is 67% of the maximum kVp
b. The average energy of the x-ray beam is approximately 40% of the maximum kVp
c. The x-ray beam produced is composed of a single photopeak with a narrow full width at half max
d. The Bremsstrahlung process is relatively efficient in that 99% of the interactions result in the production of x-ray photons
e. Bremsstrahlung interactions result in ejected electrons from atoms within the target.
b. The average energy of the x-ray beam is approximately 40% of the maximum kVp
- The approximate difference of x-ray production per unit time between single-phase self rectified generators and single-phase full-wave rectified generators is:
a. A factor of 1.5
b. A factor of 2
c. A factor of 4
d. A factor of 5
e. A factor of 10
b. A factor of 2
- Which one of the following statements concerning x-ray machines with high frequency generators is true?
a. An advantage of a high frequency x-ray machine is that they are typically better at penetrating thicker body objects than similarly rated lower frequency machines.
b. High frequency x-ray machines are typically physically larger in size than conventional (non-high frequency) machines.
c. High frequency x-ray machines minimize the “ripple effect” thus providing nearly constant voltage to the x-ray tube.
d. High frequency x-ray machines require special electrical connections that are generally cost prohibitive in veterinary medicine.
e. High frequency x-ray machines utilise single-phase full-wave rectification
c. High frequency x-ray machines minimize the “ripple effect” thus providing nearly constant voltage to the x-ray tube.
- Intensifying screen (A) has higher conversion efficiency but the same absorption efficiency and thickness as screen (B). USE OF SCREEN (A) WILL RESULT IN ____________________. (Note: Assume you use the same exposure settings)
a. Reduced image noise
b. An increase in image detail
c. Increased image noise
d. A need for greater numbers of photons to produce a similar image
e. Greater skin dose to the patient
a. Reduced image noise
- What would happen if you upgraded to terbium-activated gadolinium oxysulphide (Gd2O2S:Tb) intensifying screens but used the film designed for use with your old calcium tungstate (CaWO2) intensifying screens? Assume you use the same exposure settings as before.
a. All radiographs would appear correctly exposed
b. Only radiographs obtained with high kVp, low mAs settings would appear correctly exposed.
c. Only radiographs obtained with low kVp, high mAs settings would appear correctly exposed.
d. All radiographs would appear overexposed.
e. All radiographs would appear underexposed.
e. All radiographs would appear underexposed.
- Which one of the following statements is true regarding radiographic image noise (quantum mottle)?
a. Noise magnitude increases with increased patient thickness.
b. Noise magnitude is inversely related to exposure.
c. Quantum mottle increases as system speed decreases.
d. Film grain does not contribute to radiographic noise.
e. Quantum mottle is common in mammography.
b. Noise magnitude is inversely related to exposure.
- In single-screen, single-emulsion film screen systems, the positioning of the film and screen in the cassette with respect to the x-ray tube should be as follows to achieve greatest resolution.
a. The screen should be at the back of the cassette with the emulsion side of the film in contact with the screen
b. The screen should be at the back of the cassette with the non-emulsion side of the film in contact with the screen
c. The screen should be at the front of the cassette with the non-emulsion side of the film in contact with the screen
d. The screen should be at the front of the cassette with the emulsion side of the film in contact with the screen.
e. The screen should be at the front of the cassette with the emulsion side of the film covered in paper in contact with the screen
a. The screen should be at the back of the cassette with the emulsion side of the film in contact with the screen
- Which of the following statements regarding a photostimulable phosphor detector system (CR imaging plate) is true?
a. The light released from the imaging plate is the same colour as the stimulating laser.
b. Excited electrons return quickly to their pre-exposure level requiring processing of the plate within 10 minutes.
c. The exposure latitude of an imaging plate is about the same as a “detail” film-screen system.
d. Plates must be erased by exposure to green light
e. The first readout of the imaging plate does not release all trapped electrons forming the latent image.
e. The first readout of the imaging plate does not release all trapped electrons forming the latent image.
20 When x-rays interact with atoms in a material, the probability of occurrence of one of the following processes is directly proportional to the atoms Z3?
a. Rayleigh scattering
b. Photoelectric effect
c. Compton scattering
d. Pair production
e. Coherent scattering
b. Photoelectric effect
21 Characteristic radiation is typically associated with which interaction?
a. Rayleigh scattering
b. Photoelectric effect
c. Compton scattering
d. Pair production
e. Coherent scattering
b. Photoelectric effect
22 Which interaction below is unlikely to occur with x-rays produced from the x-ray tube within a CT scanner?
a. Rayleigh scattering
b. Photoelectric effect
c. Compton scattering
d. Pair production
e. Coherent scattering
d. Pair production
23 Which interaction’s probability of occurrence is approximately proportional to the density of the material and on the number of electrons per gram of the absorber?
a. Rayleigh scattering
b. Photoelectric effect
c. Compton scattering
d. Pair production
e. Coherent scattering
c. Compton scattering
24 Which x-ray interaction predominates when the medium is mostly water or soft tissue equivalent?
a. Rayleigh scattering
b. Photoelectric effect
c. Compton scattering
d. Pair production
e. Coherent scattering
c. Compton scattering