20 Radiography & Ultrasound Practice Questions & Answers

1. 1. A veterinary assistant is told that every imaging task in the practice must follow the ALARA principle. What does ALARA require of the imaging team?

   • A.Keeping the number of radiographs to what the client will pay for
   • B.Keeping every exposure just below the annual occupational dose limit
   • C.Keeping every exposure factor at the lowest setting the machine offers
   • D.Keeping everyone's radiation exposure as low as reasonably achievable✓ Answer

   ALARA stands for As Low As Reasonably Achievable. Because no dose of ionizing radiation is assumed to be entirely without risk, exposure is minimized through time, distance and shielding rather than simply held under a legal ceiling; the regulatory dose limit is a maximum that must not be reached, not a target. Using the lowest possible technique is also wrong, because an underexposed, non-diagnostic image forces a retake that doubles the dose to patient and staff.

   Source: NCRP Report No. 148, Radiation Protection in Veterinary Medicine — ALARA principle; 10 CFR 20.1101 radiation protection programsReport a problem with this question

2. 2. The NAVTA Essential Skills list names the personal protective equipment a veterinary assistant uses for diagnostic radiography. Which set does it name?

   • A.A lead gown, lead gloves, safety glasses, and a fitted respirator
   • B.Lead gloves, a thyroid shield, a dosimetry badge, and shoe covers
   • C.A lead gown, lead gloves, a thyroid shield, and a dosimetry badge✓ Answer
   • D.A lead gown, a thyroid shield, exam gloves, and a face shield

   The skills list names four items together: gown, gloves, thyroid guard and dosimeter badge. Each protects a different unshielded region, and the dosimeter is what documents that the protection is working. Respirators, goggles and face shields belong to chemical, dental or surgical hazards rather than to ionizing radiation, and ordinary exam gloves give no attenuation at all.

   Source: NAVTA Essential Skills for the Veterinary Assistant — Radiography and Ultrasound Imaging: radiation safety measures and PPEReport a problem with this question

3. 3. Where should a veterinary assistant wear the dosimetry badge while radiographs are being taken?

   • A.On the wrist of the hand nearest the tube head
   • B.At the collar, underneath the lead apron
   • C.At the waist, on the outside of the lead apron
   • D.At the collar, on the outside of the lead apron✓ Answer

   The badge is worn at collar level and outside the apron because it must record the dose reaching the least protected, highest-exposed part of the body — the head, eyes and thyroid. Worn under the apron it reads the shielded dose and grossly understates true exposure, and worn at the waist it misses the unshielded region entirely. A separate ring or wrist badge is added only when the hands are near the beam, as in fluoroscopy.

   Source: NCRP Report No. 148, Radiation Protection in Veterinary Medicine — personnel monitoringReport a problem with this question

4. 4. A dog needs a lateral view of the carpus, and the veterinarian asks the assistant to keep the paw extended. The assistant is wearing lead gloves. What is the correct action?

   • A.Hold the paw bare-handed with the arm stretched to the edge of the field
   • B.Hold the paw with tape and a sandbag so both hands stay out of the field✓ Answer
   • C.Hold the paw with the lead gloves, which shield the hands in the beam
   • D.Hold the paw with the lead gloves and use a lower exposure setting

   No part of any person may be placed in the primary beam, gloved or not. Lead aprons and gloves are rated to attenuate scattered radiation only; the primary beam is far more intense and passes through the glove, so gloved hands in the beam receive a substantial dose and also produce a distracting shadow on the image. Positioning aids such as tape, sandbags, foam wedges and troughs, plus sedation when the veterinarian approves it, are what replace hands.

   Source: NCRP Report No. 148, Radiation Protection in Veterinary Medicine — no part of the body in the primary beam; NAVTA Essential Skills, radiation safety and PPEReport a problem with this question

5. 5. Time, distance and shielding are the three ways occupational radiation exposure is reduced. Which statement about distance is correct?

   • A.Doubling the distance from the source has little effect on exposure
   • B.Doubling the distance from the source cuts exposure to one quarter✓ Answer
   • C.Doubling the distance from the source cuts exposure to one eighth
   • D.Doubling the distance from the source cuts exposure to one half

   Radiation intensity follows the inverse square law: it falls off with the square of the distance, so twice the distance means one quarter the intensity. This is why distance is the most effective of the three protective measures and why everyone not essential to the exposure leaves the room, while anyone who must remain stands behind a barrier or in full protective equipment, never in the beam.

   Source: NCRP Report No. 148, Radiation Protection in Veterinary Medicine — inverse square law, time/distance/shieldingReport a problem with this question

6. 6. Why is the beam collimated to the area of clinical interest so that an unexposed border shows at the edge of the finished image?

   • A.It darkens the image so a lower exposure setting can be used
   • B.It removes the need for lead markers because the field defines the side
   • C.It magnifies the region of interest so small structures are easier to see
   • D.It lowers scatter and dose and shows the beam stayed within the cassette✓ Answer

   Restricting the field to the region being imaged irradiates less tissue, so both patient dose and the scattered radiation reaching staff drop, and less scatter also means a cleaner, higher-contrast image. An unexposed margin visible on two opposing sides is the visual proof that the primary beam did not extend beyond the image receptor. Collimation does not replace left and right markers, which must still lie inside the collimated field.

   Source: NCRP Report No. 148, Radiation Protection in Veterinary Medicine — beam limitation and collimationReport a problem with this question

7. 7. A fractious dog needs abdominal radiographs and a coworker says, "it is one quick shot, just hold him." What should the assistant do?

   • A.Hold the dog with a trough, sandbags and tape after asking about sedation✓ Answer
   • B.Hold the dog while a second person makes the exposure from the doorway
   • C.Hold the dog wearing a lead apron and gloves because the exposure is brief
   • D.Hold the dog bare-handed but turn away from the tube during the exposure

   Manual restraint during an exposure is a last resort, not a routine shortcut, because it puts a person's hands and body near or inside the beam and adds repeated small doses over a career. Chemical restraint approved by the veterinarian, combined with mechanical aids such as a V-trough, sandbags, foam wedges and tape, holds the patient more still than hands do, which also reduces motion blur and the retakes that double everyone's dose. Turning away or shortening the exposure does not remove the exposure.

   Source: NCRP Report No. 148, Radiation Protection in Veterinary Medicine — restraint of animals for radiography; AAHA/AVMA guidance on chemical and mechanical restraintReport a problem with this question

8. 8. A pregnant assistant wants the additional protections that United States federal radiation regulations give a declared pregnant worker. What is required for that status?

   • A.A voluntary written declaration of the pregnancy given to the employer✓ Answer
   • B.A verbal notice to the supervisor, who then records it in the log
   • C.A physician's letter placed in the practice's radiation safety file
   • D.An automatic reassignment once the pregnancy becomes visibly apparent

   Federal rules define a declared pregnant worker as one who has voluntarily informed her employer, in writing, of the pregnancy and the estimated date of conception. The declaration is the worker's choice and may be withdrawn at any time; until it is made in writing, the ordinary occupational limits apply. Once declared, the dose limit to the embryo or fetus is 0.5 rem for the entire gestation with no more than 0.05 rem in any single month, which is far below the annual whole-body occupational limit and usually requires additional monitoring or reassignment of duties.

   Source: 10 CFR 20.1208, dose equivalent to an embryo/fetus, and 10 CFR 20.1003 definition of declared pregnant womanReport a problem with this question

9. 9. The veterinarian orders a ventrodorsal (VD) view of a cat's abdomen. How is the patient positioned and where does the beam travel?

   • A.In dorsal recumbency, with the beam entering the back and exiting the abdomen
   • B.In right lateral recumbency, with the beam entering the left side of the body
   • C.In sternal recumbency, with the beam entering the back and exiting the abdomen
   • D.In dorsal recumbency, with the beam entering the abdomen and exiting the back✓ Answer

   View names are built from the surface the beam enters followed by the surface it exits. Ventrodorsal therefore means the beam enters the ventral surface and leaves through the dorsal surface, which only happens with the animal lying on its back in dorsal recumbency, usually supported in a padded V-trough. The dorsoventral view is the mirror image: patient in sternal recumbency, beam entering the back. Confusing the two is the most common positioning error on this section.

   Source: American College of Veterinary Radiology standardized nomenclature for radiographic views; standard veterinary radiographic positioning textsReport a problem with this question

10. 10. A craniocaudal view of a dog's antebrachium is requested. What does that name tell the imaging team about the beam?

    • A.It enters the caudal surface of the limb and exits the cranial surface
    • B.It travels down the length of the limb from the elbow toward the carpus
    • C.It enters the cranial surface of the limb and exits the caudal surface✓ Answer
    • D.It enters the lateral surface of the limb and exits the medial surface

    Standardized view nomenclature names the point of entry first and the point of exit second, so craniocaudal describes a beam passing from the front of the limb to the back of it, with the limb extended and the cranial surface toward the tube. Reading the name this way tells the assistant how to position the patient without being told separately, and the same rule explains ventrodorsal, dorsoventral and the oblique view names.

    Source: American College of Veterinary Radiology standardized nomenclature for radiographic viewsReport a problem with this question

11. 11. Before a thoracic radiograph the assistant measures the patient with calipers. Where is the measurement taken, and what is it used for?

    • A.At the thinnest part of the region imaged, to keep the exposure as low as possible
    • B.At the midpoint of the whole body, to record the patient's size in the x-ray log
    • C.At the thickest part of the abdomen, to keep one setting for all of that patient's views
    • D.At the thickest part of the region imaged, to select settings from the technique chart✓ Answer

    Tissue thickness determines how much the beam is attenuated, so the technique chart is indexed to a caliper measurement of the thickest part of the specific region being imaged, taken in the position the patient will be radiographed in. Measuring a thin area or a different body part yields settings that underexpose or overexpose the film and force a retake, which doubles the dose to the patient and the staff. Each region and each view is measured separately rather than sharing one number.

    Source: Standard veterinary radiography texts (Lavin's Radiography for Veterinary Technicians) — patient measurement and technique chartsReport a problem with this question

12. 12. On a film-screen radiographic system, how do the two main exposure controls act on the image?

    • A.kVp mainly controls density, and mAs mainly controls contrast and penetration
    • B.kVp controls both density and contrast, and mAs only controls the exposure time
    • C.mAs controls both density and contrast, and kVp only controls the field size
    • D.mAs mainly controls density, and kVp mainly controls contrast and penetration✓ Answer

    mAs sets the quantity of photons produced, so it governs the overall blackness or density of the image: more mAs gives a darker film. kVp sets the energy of the photons, so it governs how far the beam penetrates and the scale of contrast — raising kVp penetrates more and produces lower, longer-scale contrast with more shades of gray. Reversing these two is the classic error, and it leads assistants to correct a too-light film with the wrong control.

    Source: Standard veterinary radiography texts (Lavin's Radiography for Veterinary Technicians) — density, contrast and exposure factorsReport a problem with this question

13. 13. A lateral abdominal image shows blurred organ margins with doubled edges, although positioning and exposure were correct. What is the most likely cause and correction?

    • A.Scatter fog; add a grid and repeat the image with the same factors
    • B.Poor film-screen contact; replace the cassette and repeat the image
    • C.Patient motion; improve restraint and shorten the exposure time✓ Answer
    • D.Underexposure; raise the exposure factors and repeat the image

    Blur with doubled or ghosted margins across the whole image is motion unsharpness, caused by the patient moving or breathing during the exposure. It is corrected by better restraint — mechanical aids and sedation approved by the veterinarian — and by a shorter exposure time, and by timing the exposure to the breathing cycle: on expiration for abdominal views and at peak inspiration for thoracic views. Underexposure produces a uniformly light image with sharp edges, and poor screen contact blurs only one localized area.

    Source: Standard veterinary radiography texts (Lavin's Radiography for Veterinary Technicians) — motion unsharpness and radiographic artifactsReport a problem with this question

14. 14. A thoracic radiograph of a correctly positioned dog shows a chain of dense round opacities superimposed over the lung fields. Which preparation step was missed?

    • A.Emptying the urinary bladder before positioning the patient
    • B.Removing the collar, tags and leash before positioning the patient✓ Answer
    • C.Wiping surgical scrub residue off the skin before positioning the patient
    • D.Clipping the hair over the thorax before positioning the patient

    Metal collars, identification tags, chain leads and harness hardware are radiopaque and cast sharply defined dense opacities that superimpose on the anatomy, where they can hide a lesion or imitate one. Every radiopaque item must be taken off the patient and out of the collimated field before the exposure, along with wet or heavily soiled hair, because the resulting retake doubles the dose to the patient and the staff. Hair is not clipped for radiography, and the bladder is not emptied for a thoracic view.

    Source: Standard veterinary radiography texts (Lavin's Radiography for Veterinary Technicians) — patient preparation and superimposed artifactsReport a problem with this question

15. 15. What identification must permanently appear on a diagnostic radiograph, and when is it applied?

    • A.Patient, client, clinic and date, applied at or before the exposure✓ Answer
    • B.Patient, client, clinic and date, written on the image after processing
    • C.Patient, breed, technique factors and date, added after processing
    • D.Patient, veterinarian, invoice number and date, added before filing

    A radiograph is a legal medical record and may be used as evidence, so its identification must be permanent and inseparable from the image: patient name or identification number, client name, clinic name and the date, placed with lead letters, a photo-label flash card or the digital header at or before the moment of exposure. Right and left lead markers must also lie inside the collimated field for the same reason. Identification handwritten or annotated on afterward can be altered and does not satisfy the requirement.

    Source: NAVTA Essential Skills for the Veterinary Assistant — labeling, filing and storage of radiographs; AVMA guidance on veterinary medical recordsReport a problem with this question

16. 16. The practice uses digital radiography. How should the assistant handle a completed study?

    • A.Export it to the client's flash drive and clear it from the imaging system
    • B.Archive it to the practice image server with the patient data left intact✓ Answer
    • C.Save it to the imaging computer's desktop and delete it once it is printed
    • D.Rename each file with the owner's phone number so it is easier to find

    Digital images are part of the patient's permanent medical record and belong to the practice, so they are archived to the practice's image server or storage system and backed up, with the embedded patient, client, clinic and date information preserved unchanged. The client is entitled to a copy on request, not to the original, and deleting or overwriting the study after printing or exporting destroys a record the practice is required to retain. Renaming files strips the standard identifiers that link an image to the right patient.

    Source: NAVTA Essential Skills for the Veterinary Assistant — filing and storage of film or digital radiographs; AVMA guidance on ownership and retention of veterinary medical recordsReport a problem with this question

17. 17. During one study, two exposures had to be repeated because the patient moved. What does the assistant enter in the practice's x-ray log?

    • A.Only the exposures for which the client was charged on the invoice
    • B.Only the exposures that produced the images kept in the record
    • C.Only the full record of every exposure, repeats and who made them✓ Answer
    • D.Only the total number of studies the practice performed that day

    The x-ray log exists to track radiation output and quality, so it records each exposure with the date, patient and client identification, the body part and view, the technique factors and measured thickness, the number of exposures including every retake, and the person who made them. Recording retakes is the entire point: they are the practice's measure of how much avoidable dose is being delivered and where training or technique needs attention. Logging only the images that were kept hides exactly the information the log is meant to capture.

    Source: NAVTA Essential Skills for the Veterinary Assistant — maintaining the x-ray log; NCRP Report No. 148, record keeping in veterinary radiation safety programsReport a problem with this question

18. 18. A dog is prepared for an abdominal ultrasound: the area is clipped, wiped with alcohol, and covered with a generous layer of coupling gel. Why is this preparation necessary?

    • A.Gel carries the electrical current the probe needs to reach the deeper organs
    • B.Hair and skin oils absorb the sound waves and can overheat the patient's skin
    • C.Air trapped between probe and skin reflects the sound beam and ruins the image✓ Answer
    • D.Alcohol and gel cool the probe so it can be run at a higher frequency setting

    Ultrasound is transmitted by sound waves, which are almost entirely reflected back at any soft tissue to air interface, so even a thin film of air under the probe blocks the beam and produces artifact that can obscure or mimic disease. Clipping removes the hair that traps air, alcohol wets and cleans the skin surface, and a liberal layer of gel fills the remaining space so the beam passes into the patient. The probe emits no ionizing radiation and no electrical current into the patient.

    Source: NAVTA Essential Skills for the Veterinary Assistant — ultrasound patient preparation; standard veterinary diagnostic imaging texts on acoustic couplingReport a problem with this question

19. 19. How does the assistant's personal protection differ when restraining a patient for an abdominal ultrasound rather than for radiographs?

    • A.A lead apron is still needed, because the transducer emits low-level radiation
    • B.A dosimetry badge is still needed, because the exposure accumulates over time
    • C.A thyroid shield is still needed, because the beam scatters back off the patient
    • D.No lead or badge is needed, because ultrasound uses sound, not ionizing radiation✓ Answer

    Diagnostic ultrasound images with high-frequency sound waves and produces no ionizing radiation, so there is no dose to monitor, no lead protective equipment and no restriction on hands-on restraint. That is why an assistant may comfortably hold the limbs of a patient lying in dorsal recumbency in a padded V-trough for an abdominal scan, and why letting the animal settle before the study is worth the time: a calm patient swallows less air and struggles less, both of which improve the image.

    Source: NAVTA Essential Skills for the Veterinary Assistant — ultrasound restraint and preparation; NCRP Report No. 148 (scope limited to ionizing radiation)Report a problem with this question

20. 20. An assistant finishes a lateral abdominal radiograph, notices an obvious abnormal opacity, and the owner asks what the image shows. What should the assistant do?

    • A.Explain that the veterinarian reviews the images and will discuss the findings✓ Answer
    • B.Say the image looks normal so the owner is not worried while they wait
    • C.Describe the opacity and add that the veterinarian will confirm the diagnosis
    • D.Say the image looks abnormal and offer the most likely explanations for it

    Producing the image and interpreting it are separate responsibilities: the veterinary assistant positions, exposes, processes, labels and logs the study, while diagnosis, prognosis and the discussion of findings belong to the veterinarian, who is legally responsible for them. Describing or naming what an opacity might be is still interpretation, and telling the owner the image is normal is both interpretation and potentially false reassurance. Precisely what an assistant may do beyond this depends on the state practice act and on what the veterinarian has delegated.

    Source: AVMA Model Veterinary Practice Act — veterinarian responsibility for diagnosis and supervision of non-credentialed staff; NAVTA Approved Veterinary Assistant program guidance on scopeReport a problem with this question

Practice questions based on the NAVTA veterinary assistant skill categories and standard veterinary assisting practice. This site is not affiliated with or endorsed by NAVTA. Note that the Approved Veterinary Assistant credential requires completing a NAVTA-approved training program before you may sit the exam — this bank is study material, not a substitute for that program, and it cannot cover the hands-on skills your program assesses in a clinic. What an assistant is permitted to do is set by your state's veterinary practice act and by what the supervising veterinarian delegates, so nothing here should be read as authorising a task where you work. About the AVA credential →