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CAMRT RTR Exam practice questions

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Question 1Radiological Technology

In a diagnostic x-ray tube, the majority of the photons in the useful beam are produced by which process?

  1. Deceleration of incident electrons in the Coulomb field of anode nuclei Correct answer.
  2. Compton scattering within the tube housing
  3. Photoelectric absorption within the anode target
  4. Ejection of K-shell electrons from anode atoms

Explanation

Bremsstrahlung occurs when incident electrons are decelerated by the nuclear Coulomb field of the target, producing a continuous photon spectrum. Because most electron interactions are of this type, bremsstrahlung accounts for the bulk of the useful beam, while characteristic emission contributes only discrete energies at a small fraction of total output.

Question 2Radiological Technology

What is the Canadian effective dose limit for a radiation worker's whole body?

  1. 500 mSv per year
  2. 50 mSv in any single year Correct answer.
  3. 1 mSv per year
  4. 150 mSv per year

Explanation

The regulatory framework sets an effective dose limit of 20 mSv per year averaged over five consecutive years, with a maximum of 50 mSv permitted in any one year. The 1 mSv figure applies to members of the general public, not occupationally exposed workers.

Question 3Radiological Technology

If mAs is increased from 5 mAs to 10 mAs while all other exposure factors are held constant, what is the effect on the image receptor?

  1. The number of photons reaching the receptor is doubled Correct answer.
  2. The half-value layer of the beam is doubled
  3. The receptor exposure is halved
  4. The effective energy of the beam is doubled

Explanation

mAs is the product of tube current and exposure time, so it is directly proportional to the number of electrons crossing the tube and therefore to the number of photons emitted. Doubling mAs doubles receptor exposure without altering the photon energy spectrum.

Question 4Radiological Technology

Which describes correct positioning for a PA projection of the chest?

  1. Patient's back against the receptor, chin elevated, shoulders rolled forward
  2. Patient supine with the cassette beneath the thorax, exposed at end expiration
  3. Patient's anterior chest against the receptor, shoulders rotated forward, chin elevated Correct answer.
  4. Patient lateral with arms elevated above the head, exposed at suspended expiration

Explanation

A PA chest requires the anterior chest wall against the receptor, with the shoulders rotated forward so the scapulae are projected clear of the lung fields. The chin is elevated to keep it out of the superior image and exposure is made on full suspended inspiration.

Question 5Radiological Technology

Which contrast agent is appropriate for an intravenous urographic examination?

  1. A barium sulfate suspension
  2. A low-osmolar non-ionic iodinated agent Correct answer.
  3. A gadolinium chelate
  4. Carbon dioxide gas

Explanation

Excretory urography requires a water-soluble iodinated agent given intravenously so that it is filtered by the kidneys and opacifies the collecting system. Low-osmolar non-ionic agents are preferred for their reduced osmolality and better patient tolerance.

Question 6Radiological Technology

Which range represents a normal resting adult heart rate?

  1. 40 to 60 beats per minute
  2. 100 to 140 beats per minute
  3. 140 to 180 beats per minute
  4. 60 to 100 beats per minute Correct answer.

Explanation

A normal adult resting heart rate is generally accepted as 60 to 100 beats per minute. Rates persistently below 60 are termed bradycardia and rates above 100 are termed tachycardia, both of which warrant reporting before contrast administration.

Question 7Radiological Technology

In digital radiography, the exposure index primarily communicates which information?

  1. The absorbed dose at the patient's skin surface
  2. The contrast resolution of the display monitor
  3. The amount of radiation reaching the detector compared with the expected value Correct answer.
  4. The spatial resolution of the detector

Explanation

The exposure index is a manufacturer-derived number that indicates how much signal reached the receptor relative to the expected value for that body part and projection. It is used to judge whether technique was adequate and to maintain consistency between images, not to express patient dose or resolution.

Question 8Radiological Technology

If source-to-image distance is increased from 100 cm to 200 cm with no other change, the exposure at the receptor becomes:

  1. Four times the original value
  2. One half of the original value
  3. Twice the original value
  4. One quarter of the original value Correct answer.

Explanation

X-ray intensity follows the inverse square law, varying inversely with the square of the distance from the source. Doubling the distance increases the denominator by a factor of four, so receptor exposure falls to one quarter and mAs must be increased fourfold to maintain it.

Question 9Radiological Technology

Replacing an 8:1 grid with a 16:1 grid of the same frequency will produce which result?

  1. Greater removal of scatter and a requirement for higher mAs Correct answer.
  2. A larger useful radiation field at the receptor
  3. Improved scatter cleanup with no change in patient dose
  4. Less removal of scatter and a requirement for lower mAs

Explanation

A higher grid ratio uses taller lead strips, so it absorbs a larger proportion of scattered photons and improves contrast. Because some primary photons are also absorbed, mAs must be increased to maintain receptor exposure, which raises patient dose.

Question 10Radiological Technology

For a PA axial (Caldwell) projection of the skull, the central ray is directed:

  1. Perpendicular to the receptor at the level of the external auditory meatus
  2. 25 degrees cephalad, exiting at the vertex
  3. 30 degrees caudad, exiting at the acanthion
  4. 15 degrees caudad, exiting at the nasion Correct answer.

Explanation

The Caldwell projection angles the tube 15 degrees caudad so the central ray passes through the frontal bone and exits at the nasion, projecting the petrous ridges into the lower third of the orbits. This demonstrates the frontal sinus and orbital margins.

Question 11Radiological Technology

What is the primary radiation-protection benefit of pulsed fluoroscopy compared with continuous fluoroscopy?

  1. It reduces patient and staff dose by limiting the time the beam is on Correct answer.
  2. It removes the need for collimation
  3. It increases the diameter of the field of view
  4. It increases the spatial resolution of the image intensifier

Explanation

Pulsed fluoroscopy produces x-rays in short discrete bursts rather than continuously, so the total beam-on time and therefore dose are reduced while preserving the displayed frame rate. Collimation and other protective practices remain necessary.

Question 12Radiological Technology

Increasing the window width on a displayed computed tomography image will:

  1. Decrease the range of Hounsfield units displayed
  2. Alter the attenuation values stored in the image data
  3. Increase displayed contrast and make image noise more conspicuous
  4. Display a broader range of Hounsfield units and reduce apparent contrast Correct answer.

Explanation

Window width defines how many Hounsfield units are mapped to the available gray levels, so a wider window covers more tissue densities and compresses them into a flatter, lower-contrast display. Window level is unchanged and the underlying data are not modified.

Question 13Radiological Technology

On an erect chest image, a small pneumothorax is recognised by which finding?

  1. Blunting of the costophrenic angle
  2. A visible visceral pleural line with no lung markings peripheral to it Correct answer.
  3. Air bronchograms within a consolidated lobe
  4. Uniform increased opacity of the affected hemithorax

Explanation

Air in the pleural space separates the visceral pleura from the chest wall, creating a thin white pleural line beyond which vascular markings are absent. Erect positioning allows air to collect at the apex, making a small collection easier to detect.

Question 14Radiological Technology

Which medication is first-line for a moderate anaphylactic reaction to iodinated contrast medium?

  1. Intramuscular epinephrine Correct answer.
  2. Sublingual nitroglycerin
  3. Oral diphenhydramine
  4. Intravenous furosemide

Explanation

Intramuscular epinephrine into the anterolateral thigh is the first-line treatment for anaphylaxis because it reverses bronchospasm and hypotension through alpha and beta adrenergic effects. Antihistamines and corticosteroids are adjuncts that do not treat the acute airway and circulatory compromise.

Question 15Radiological Technology

The half-value layer of an x-ray beam is defined as:

  1. The kVp at which tube output is halved
  2. The distance at which beam intensity falls to half its original value
  3. The thickness of a specified absorber that reduces beam intensity by half Correct answer.
  4. The exposure time required to double receptor exposure

Explanation

Half-value layer is a measure of beam quality expressed as the thickness of a stated material, usually aluminium, that attenuates the beam to half its intensity. A higher half-value layer indicates a more penetrating, higher-energy beam.

Question 16Radiological Technology

The AP oblique (Grashey) projection of the shoulder is performed in order to:

  1. Demonstrate the humeral head in internal rotation
  2. Demonstrate the acromioclavicular joint space
  3. Open the glenohumeral joint space Correct answer.
  4. Profile the scapular body and acromion

Explanation

Rotating the patient 35 to 45 degrees places the glenohumeral joint space parallel to the image receptor, so the joint is demonstrated open rather than overlapped. This projection is used to assess joint space narrowing, dislocation, and degenerative change.

Question 17Radiological Technology

In computed radiography, the latent image is stored in which component?

  1. An amorphous selenium layer that converts charge directly
  2. A thin-film transistor array without a storage layer
  3. A photostimulable phosphor plate Correct answer.
  4. A caesium iodide scintillator coupled to a charge-coupled device

Explanation

Computed radiography uses a photostimulable phosphor, typically barium fluorohalide doped with europium, which traps electrons in metastable states after x-ray exposure. The plate is then scanned by a laser to release the stored energy as light.

Question 18Radiological Technology

With source-to-image distance held constant, increasing the object-to-image distance will:

  1. Increase magnification and reduce recorded detail Correct answer.
  2. Increase magnification with no effect on recorded detail
  3. Decrease magnification and improve recorded detail
  4. Leave magnification unchanged but reduce contrast

Explanation

Magnification is determined by the ratio of source-to-image distance to source-to-object distance, so moving the object farther from the receptor increases magnification. Greater magnification spreads the penumbra over more pixels, reducing recorded detail.

Question 19Radiological Technology

Quantum mottle becomes most apparent when:

  1. mAs is excessive and kVp is very high
  2. A large focal spot is used with a long source-to-image distance
  3. Too few photons reach the image receptor Correct answer.
  4. A high-ratio grid is used with adequate mAs

Explanation

Quantum mottle is statistical fluctuation in the number of photons reaching the receptor and becomes visible when photon numbers are low, such as with very short exposure times or high attenuation. Increasing mAs raises photon count and smooths the noise.

Question 20Radiological Technology

Which practice best reduces the need for repeat exposures when radiographing a young child?

  1. Using the shortest practical exposure time with effective immobilization Correct answer.
  2. Applying adult exposure factors scaled only by patient weight
  3. Sedating every child regardless of the examination
  4. Using a fixed 200 cm source-to-image distance for all projections

Explanation

Short exposure times minimise motion artefact, and adequate immobilization by parents or devices prevents involuntary movement during the exposure. Both measures reduce the likelihood that the image will need to be repeated.

Question 21Radiological Technology

Characteristic K-shell x-rays can be produced in a tungsten target only when the incident electron:

  1. Is deflected by the nucleus without transferring energy
  2. First ejects an electron from an outer shell
  3. Has energy exceeding the K-shell binding energy of tungsten Correct answer.
  4. Has energy below the K-shell binding energy of tungsten

Explanation

Characteristic emission requires removal of an inner-shell electron, which can only occur if the incident electron transfers at least the binding energy of that shell. For tungsten the K-shell binding energy is about 69.5 keV, so incident electrons must exceed this value for K-characteristic photons to appear.

Question 22Radiological Technology

A computed tomography acquisition performed at a pitch of 2.0 compared with a pitch of 1.0, with identical mAs and collimation, will:

  1. Double the in-plane spatial resolution
  2. Increase patient dose proportionally to the pitch
  3. Move the table twice as far per rotation and reduce dose for the same image noise Correct answer.
  4. Require the reconstructed slice thickness to double

Explanation

Pitch is the table feed per gantry rotation divided by the total beam collimation, so a pitch of 2.0 doubles the table speed and spreads the same tube output over a longer volume. Consequently, dose per unit volume falls, although image noise increases unless mAs is raised.

Question 23Radiological Technology

A trauma patient with suspected cervical spine injury cannot be moved from the supine position. How is the cross-table lateral cervical spine projection performed?

  1. Patient supine with a horizontal beam centred at C4 and the receptor vertical beside the neck Correct answer.
  2. Patient supine with a vertical beam centred at the thyroid cartilage
  3. Patient upright with a horizontal beam centred at C4
  4. Patient prone with the beam angled 15 degrees cephalad

Explanation

The cross-table lateral is performed without moving the patient: the receptor is placed vertically alongside the neck and a horizontal beam is directed to C4. The shoulders are depressed so that all seven cervical vertebrae and the C7-T1 junction are included.

Question 24Radiological Technology

A flat-field (uniformity) test performed on a digital radiography detector is designed primarily to detect:

  1. Changes in focal spot size
  2. Drift in automatic exposure control calibration
  3. Misalignment of the collimator
  4. Variations in detector response across the imaging field Correct answer.

Explanation

A flat-field test exposes the detector uniformly and reveals gain variations, dead pixels, and non-uniform response across the field that would appear as artefacts on clinical images. Correction maps are then applied or the detector is serviced.

Question 25Radiological Technology

Which contrast agent is preferred for a gastrointestinal study in a patient with suspected bowel perforation?

  1. A water-soluble iodinated agent Correct answer.
  2. An oral gadolinium chelate
  3. A high-density barium sulfate suspension
  4. Barium sulfate combined with air insufflation

Explanation

If perforation is suspected, a water-soluble iodinated agent is used because it is absorbed and excreted if it enters the peritoneal cavity. Barium sulfate is insoluble and can provoke a severe inflammatory peritonitis if it leaks outside the bowel.

Question 26Radiological Technology

In the photoelectric effect, the incident photon is completely absorbed by an atom and most commonly ejects which particle?

  1. The nucleus
  2. A second photon in the beam
  3. An inner-shell electron Correct answer.
  4. An outer-shell electron

Explanation

The photon transfers all of its energy to an inner-shell electron, which is ejected as a photoelectron. The vacancy is then filled by an outer-shell electron, producing characteristic radiation.

Question 27Radiological Technology

Thermionic emission in the x-ray tube refers to the:

  1. Release of electrons from a heated filament Correct answer.
  2. Production of bremsstrahlung photons at the target
  3. Acceleration of electrons from cathode to anode
  4. Dissipation of heat by the rotating anode

Explanation

Heating the filament raises electron energy until electrons are emitted from its surface, supplying tube current. Those electrons are then accelerated toward the anode by the applied voltage.

Question 28Radiological Technology

Increasing tube voltage from 70 kVp to 90 kVp, with mAs held constant, changes the bremsstrahlung spectrum by:

  1. Increasing the maximum photon energy and shifting the spectrum to higher energies Correct answer.
  2. Producing a spectrum with only characteristic peaks and no continuous component
  3. Shifting the spectrum to lower energies and reducing total intensity
  4. Leaving the maximum photon energy unchanged while reducing intensity

Explanation

Higher kVp gives electrons greater kinetic energy, raising the maximum bremsstrahlung photon energy and shifting the continuous spectrum to higher energies. Total output also increases, while characteristic peaks remain superimposed.

Question 29Radiological Technology

The primary reason for selecting a small focal spot is to:

  1. Increase beam filtration
  2. Shorten the exposure time
  3. Decrease geometric unsharpness Correct answer.
  4. Reduce patient dose

Explanation

A smaller focal spot reduces geometric unsharpness, improving spatial resolution. It also concentrates heat, which limits the maximum mA that can be used.

Question 30Radiological Technology

When radiographing the entire femur, the thicker proximal portion should be positioned toward which side of the beam to compensate for the anode heel effect?

  1. Anode side
  2. The central ray only
  3. Cathode side Correct answer.
  4. Either side, because intensity is uniform

Explanation

The anode heel effect reduces beam intensity on the anode side and increases it on the cathode side. The thicker body part is therefore placed toward the cathode side to receive greater intensity.

Question 31Radiological Technology

Added filtration in an x-ray tube mainly:

  1. Removes low-energy photons from the beam Correct answer.
  2. Converts bremsstrahlung photons into characteristic photons
  3. Increases the proportion of low-energy photons reaching the patient
  4. Increases spatial resolution by narrowing the focal spot

Explanation

Filtration preferentially absorbs lower-energy photons, raising the average beam energy and reducing patient skin dose. It does not change focal spot size or convert photon types.

Question 32Radiological Technology

If an AEC chamber is positioned over a very dense structure, the automatic exposure control will most likely:

  1. Change the focal spot size automatically
  2. Terminate the exposure earlier than needed
  3. Increase exposure time until the chamber receives enough radiation Correct answer.
  4. Produce an image with excessive quantum mottle

Explanation

AEC terminates the exposure when the selected chamber reaches a preset signal. A dense structure attenuates the beam strongly, so exposure time lengthens to deliver enough radiation to the chamber.

Question 33Radiological Technology

Reducing the collimated field size on a radiograph, with exposure factors unchanged, generally:

  1. Lowers subject contrast
  2. Reduces the amount of scattered radiation produced Correct answer.
  3. Increases scatter reaching the image receptor
  4. Increases patient dose outside the field

Explanation

Collimation limits the volume of tissue irradiated, so less Compton scatter is produced and contrast improves. Patient dose outside the field is also reduced.

Question 34Radiological Technology

In digital radiography, the histogram of an image represents the:

  1. Detector exposure index calibration
  2. Dose-area product for the study
  3. Spatial resolution of the detector
  4. Distribution of pixel values in the image Correct answer.

Explanation

A histogram plots the frequency of pixel values, and image processing uses it to set display contrast and brightness. It is not a direct measure of dose or spatial resolution.

Question 35Radiological Technology

Which handling error is most likely to cause a loss of signal or artifact in a computed radiography imaging plate?

  1. Reading the plate immediately after exposure
  2. Storing the plate in a protective cassette
  3. Erasing the plate after readout
  4. Exposing the plate to light before readout Correct answer.

Explanation

The CR latent image is stored in the photostimulable phosphor and can fade or be altered by light exposure before readout. Immediate readout, proper erasing, and protective storage are correct handling practices.

Question 36Radiological Technology

The DICOM standard is primarily concerned with:

  1. Radiation dose reporting to a registry
  2. Compression of digital radiography raw data only
  3. Scheduling of radiology appointments
  4. Exchange and communication of medical images Correct answer.

Explanation

DICOM defines formats and communication protocols for medical images and related information between devices. It supports interoperability among imaging modalities, workstations, and archives.

Question 37Radiological Technology

Increasing the window level on a displayed CT image primarily:

  1. Makes the image appear darker Correct answer.
  2. Narrows the range of displayed Hounsfield units
  3. Increases the contrast between soft tissues
  4. Makes the image appear brighter

Explanation

Window level is the midpoint Hounsfield unit value of the displayed gray scale. Raising it places a given tissue value nearer the dark end, so the image appears darker; window width controls contrast.

Question 38Radiological Technology

On a CT image, water is assigned a Hounsfield unit value of:

  1. 0 HU Correct answer.
  2. +1000 HU
  3. -1000 HU
  4. +100 HU

Explanation

CT numbers are calibrated with water at 0 HU, air near -1000 HU, and dense bone at approximately +1000 HU or higher. These reference values allow tissue attenuation to be compared.

Question 39Radiological Technology

Reconstructing a CT image with a sharp (bone) kernel instead of a smooth kernel will generally produce:

  1. Higher spatial resolution and more noise Correct answer.
  2. Higher spatial resolution and less noise
  3. Lower spatial resolution and less noise
  4. Lower spatial resolution and more noise

Explanation

Sharp kernels enhance high-frequency edges, improving spatial resolution but also amplifying noise. Smooth kernels suppress noise at the cost of spatial resolution.

Question 40Radiological Technology

Automatic brightness control in fluoroscopy adjusts which parameters to maintain a constant display brightness?

  1. Focal spot size and filtration
  2. kVp and mA Correct answer.
  3. Grid ratio and collimation
  4. Pulse rate and frame averaging only

Explanation

Automatic brightness control varies kVp and/or mA to compensate for changes in attenuation and keep display brightness stable. Other parameters may be selected by the operator but are not the primary automatic pair.

Question 41Radiological Technology

The main purpose of breast compression in mammography is to:

  1. Increase the object-to-image distance
  2. Reduce breast thickness and improve image quality Correct answer.
  3. Reduce the required kVp to below 20 kVp
  4. Eliminate the need for a grid

Explanation

Compression reduces breast thickness, spreads tissue, reduces scatter and dose, and improves spatial resolution. It does not remove the need for a grid.

Question 42Radiological Technology

The ALARA principle in radiation protection requires that doses be:

  1. At the legal annual limit
  2. Measured with a personal dosimeter
  3. As low as reasonably achievable Correct answer.
  4. Reduced only for pregnant patients

Explanation

ALARA means optimizing protection so that doses are as low as reasonably achievable, with economic and social factors considered. It applies to all radiation exposures, not only pregnancy.

Question 43Radiological Technology

Before administering iodinated contrast medium, which history finding is most important to identify?

  1. Previous seasonal allergies
  2. Current use of antihistamines
  3. Family history of diabetes
  4. Prior moderate reaction to iodinated contrast Correct answer.

Explanation

A previous moderate or severe reaction to iodinated contrast is a major risk factor that may require premedication or an alternative study. Seasonal allergies and diabetes affect risk but are less specific predictors.

Question 44Radiological Technology

Standard precautions require gloves to be worn when:

  1. Greeting a patient in the waiting area
  2. Performing a routine radiographic examination with no contact
  3. Entering any patient room
  4. Contact with blood or body fluids is anticipated Correct answer.

Explanation

Gloves are indicated when contact with blood, body fluids, non-intact skin, or mucous membranes is anticipated. They are not required for routine tasks with no anticipated contact.

Question 45Radiological Technology

In a PA projection of the chest, the central ray enters the patient through the:

  1. Anterior thorax and exits posteriorly
  2. Left side and exits right
  3. Right side and exits left
  4. Posterior thorax and exits anteriorly Correct answer.

Explanation

PA means posterior-to-anterior: the central ray enters the posterior thorax and exits anteriorly. An AP projection would enter anteriorly and exit posteriorly.

Question 46Radiological Technology

On an erect chest radiograph, lobar atelectasis typically produces:

  1. Volume loss with increased opacity in the affected lobe Correct answer.
  2. Bilateral hilar enlargement without opacity
  3. Hyperinflation with increased lucency
  4. A pleural line with absent lung markings

Explanation

Atelectasis causes alveolar collapse, reducing volume and increasing density in the affected lobe; fissures may shift toward the collapsed lobe. A pleural line with absent markings suggests pneumothorax.

Question 47Radiological Technology

Increasing patient thickness while keeping kVp and mAs constant will have which effect on the image?

  1. Less scatter reaches the receptor and contrast rises
  2. Scatter rises, but contrast rises because more tissue is irradiated
  3. Scatter is unchanged because kVp is constant
  4. More scatter reaches the receptor and contrast falls Correct answer.

Explanation

Thicker tissue increases the path length and the amount of Compton scatter produced. More scatter reaching the receptor reduces contrast and adds noise, even when kVp is unchanged.

Question 48Radiological Technology

A detector with higher detective quantum efficiency (DQE) will, for the same exposure, generally produce:

  1. Higher spatial resolution but lower contrast
  2. Lower signal-to-noise ratio and higher patient dose
  3. More geometric unsharpness
  4. Higher signal-to-noise ratio for a given dose Correct answer.

Explanation

DQE measures how efficiently incident x-rays are converted into useful signal. A higher DQE provides better signal-to-noise ratio at the same dose or allows a lower dose for the same signal-to-noise ratio.

Question 49Radiological Technology

The volume CT dose index (CTDIvol) provides an estimate of:

  1. Average absorbed dose within the scanned volume Correct answer.
  2. Total effective dose for the entire study
  3. Dose from scattered radiation outside the scan field
  4. Dose to a specific patient's skin surface

Explanation

CTDIvol represents the average absorbed dose per unit volume in the scanned volume, accounting for pitch. It is not a patient-specific effective dose.

Question 50Radiological Technology

A focused grid is used at a source-to-image distance shorter than its specified focal range. What is the most likely result?

  1. Uniformly increased receptor dose
  2. Complete elimination of scatter
  3. Improved contrast across the entire image
  4. Peripheral grid cut-off Correct answer.

Explanation

Focused grid strips are angled to match a specific focal distance. Using the grid outside that range causes primary photons at the periphery to strike the strips and be absorbed, producing cut-off.