Radiographer Prometric exam questions with answers

1. Question 1Radiographic Positioning & Imaging Procedureseasy

   Why is a PA chest radiograph routinely taken at a source-to-image distance of about 180 cm (72 inches)?

   1. ATo reduce the exposure time needed for the radiograph
   2. BTo reduce magnification of the heart and improve image sharpness
   3. CTo increase the contrast between the lungs and the mediastinum
   4. DTo allow a lower kVp to be used for the examination
   Show answer and explanation▾

   Answer: B. To reduce magnification of the heart and improve image sharpness

   Increasing SID reduces the divergence of the beam, so the heart and mediastinum are less magnified and geometric unsharpness is reduced, which makes cardiothoracic ratio assessment more accurate. A longer SID actually needs more mAs because of the inverse square law, so it does not shorten exposure time.

2. Question 2Radiographic Positioning & Imaging Proceduresmedium

   A patient has tenderness in the anatomical snuffbox after a fall onto an outstretched hand. Which modification of the PA wrist projection best demonstrates the scaphoid without foreshortening?

   1. ARadial deviation of the wrist
   2. BFull flexion of the wrist
   3. CSupination of the forearm
   4. DUlnar deviation of the wrist
   Show answer and explanation▾

   Answer: D. Ulnar deviation of the wrist

   Ulnar deviation tilts the scaphoid into a more horizontal position, elongating it and opening the surrounding joint spaces, so the waist is better demonstrated; cranial angulation of the beam can also be added. Radial deviation does the opposite, foreshortening the scaphoid and closing the lateral joint spaces.

3. Question 3Anatomy, Physiology & Pathology (Clinical Principles)medium

   A patient with sudden severe abdominal pain is suspected of having a perforated peptic ulcer. Which projection is most sensitive for detecting a small pneumoperitoneum?

   1. AErect chest film after about 10 minutes upright
   2. BSupine AP abdomen taken immediately on arrival
   3. CErect AP abdomen taken as soon as the patient sits up
   4. DPA chest radiograph taken on full expiration
   Show answer and explanation▾

   Answer: A. Erect chest film after about 10 minutes upright

   Free gas rises under the diaphragm, and an erect chest radiograph shows the domes tangentially; keeping the patient upright for about 10 minutes allows small amounts of gas to collect there. A supine abdomen can miss small volumes of free gas, and imaging immediately after sitting up does not allow enough time for gas to migrate.

4. Question 4Image Production, Processing & Quality (Operation of Equipment)hard

   A technique of 10 mAs at 100 cm SID gives a good knee radiograph. The SID must be increased to 150 cm. Using the density maintenance formula, what mAs is needed to keep the same receptor exposure?

   1. A15 mAs
   2. B6.7 mAs
   3. C22.5 mAs
   4. D4.4 mAs
   Show answer and explanation▾

   Answer: C. 22.5 mAs

   Receptor exposure follows the inverse square law, so new mAs = old mAs x (new SID / old SID) squared = 10 x (150/100)^2 = 10 x 2.25 = 22.5 mAs. Using 15 mAs scales linearly with distance and underexposes the receptor, while 4.4 mAs applies the inverse square relationship the wrong way.

5. Question 5Radiation Physics & X-ray Productionmedium

   A technique of 70 kVp and 20 mAs is used. The radiographer increases the kVp to 80. Using the 15% rule, what mAs maintains approximately the same receptor exposure?

   1. A40 mAs
   2. B20 mAs
   3. C10 mAs
   4. D5 mAs
   Show answer and explanation▾

   Answer: C. 10 mAs

   Increasing kVp by about 15% (70 to roughly 80 kVp) approximately doubles receptor exposure, so mAs is halved from 20 to 10 to compensate, reducing patient dose while lowering contrast. Doubling mAs to 40 would quadruple exposure overall and overexpose the image.

6. Question 6Radiation Physics & X-ray Productioneasy

   In the diagnostic energy range, which photon interaction with soft tissue is the main source of scattered radiation and therefore of occupational exposure?

   1. ACompton scattering
   2. BPhotoelectric absorption
   3. CCoherent (classical) scattering
   4. DPair production
   Show answer and explanation▾

   Answer: A. Compton scattering

   Compton scattering dominates in soft tissue across most diagnostic energies and produces scattered photons that degrade image contrast and expose staff. Photoelectric absorption deposits all the photon energy in the patient, producing contrast but not scatter, and pair production requires energies above 1.02 MeV.

7. Question 7Image Production, Processing & Quality (Operation of Equipment)hard

   A radiograph taken with a focused grid shows adequate density in the centre of the image but severe loss of density at both lateral edges. What is the most likely cause?

   1. AThe grid was tilted off-level
   2. BThe central ray was laterally decentred to the grid
   3. CThe grid ratio was too low for the kVp used
   4. DThe focused grid was placed upside down
   Show answer and explanation▾

   Answer: D. The focused grid was placed upside down

   An upside-down focused grid aligns only the central lead strips with the beam, causing severe grid cut-off at both edges while the centre remains exposed. Off-level and lateral decentring errors produce a uniform or one-sided loss of density across the image, and a low grid ratio causes more scatter fog rather than cut-off.

8. Question 8Radiation Protection & Safetyhard

   A radiographer declares her pregnancy to her employer. According to ICRP recommendations, what dose limit applies to the embryo or fetus for the remainder of the pregnancy?

   1. AAbout 5 mSv
   2. BAbout 1 mSv
   3. CAbout 6 mSv
   4. DAbout 20 mSv
   Show answer and explanation▾

   Answer: B. About 1 mSv

   ICRP recommends that once pregnancy is declared, working conditions should ensure the dose to the embryo or fetus does not exceed about 1 mSv for the remainder of the pregnancy, the same as the public limit. 20 mSv is the annual effective dose limit for occupationally exposed workers and does not apply to the fetus.

9. Question 9Radiation Protection & Safetyeasy

   Which of the following is a stochastic effect of ionising radiation?

   1. ARadiation-induced cancer
   2. BSkin erythema
   3. CCataract formation
   4. DTemporary epilation
   Show answer and explanation▾

   Answer: A. Radiation-induced cancer

   Stochastic effects, such as cancer and heritable effects, have a probability that increases with dose and are assumed to have no threshold, while their severity is independent of dose. Erythema, epilation and cataracts are deterministic (tissue) reactions that occur above a threshold dose and become more severe as the dose increases.

10. Question 10Patient Care & Managementmedium

    A patient standing for an erect chest radiograph becomes pale, sweaty and lightheaded and says he is going to faint. What should the radiographer do first?

    1. ASit him upright on a chair with his head between his knees and continue
    2. BGive him a glass of water and complete the exposure quickly
    3. CHelp him lie down and elevate his legs while calling for assistance
    4. DAsk him to hold the chest stand firmly until the feeling passes
    Show answer and explanation▾

    Answer: C. Help him lie down and elevate his legs while calling for assistance

    These are prodromal signs of vasovagal syncope; lying the patient flat with legs raised restores cerebral perfusion and prevents injury from a fall, and the patient's observations should be checked. Completing the exposure or having him hold on while standing risks a fall from height, and the examination should resume only when he has recovered.

11. Question 11Contrast Media, Pharmacology & Drug Administrationhard

    A patient taking metformin is booked for contrast-enhanced CT with intravenous iodinated contrast. Her eGFR is 25 mL/min/1.73 m2. What is the recommended approach?

    1. AContinue metformin without interruption because the contrast dose is small
    2. BWithhold metformin from the time of the scan for 48 hours and recheck renal function
    3. CStop metformin for 48 hours before the scan and restart immediately afterwards
    4. DCancel the scan because iodinated contrast is contraindicated with metformin
    Show answer and explanation▾

    Answer: B. Withhold metformin from the time of the scan for 48 hours and recheck renal function

    ACR and RCR guidance advise that patients with an eGFR below 30 mL/min/1.73 m2 or acute kidney injury should withhold metformin at the time of contrast administration and for 48 hours afterwards, restarting when renal function is confirmed stable, to reduce the rare risk of lactic acidosis. Continuing metformin without interruption is appropriate only when eGFR is 30 or above with no AKI.

12. Question 12Contrast Media, Pharmacology & Drug Administrationmedium

    During power injection of iodinated contrast for CT, the patient reports pain and the forearm swells around the cannula site. After stopping the injection, which action is most appropriate?

    1. AFlush the cannula with saline to disperse the contrast into the vein
    2. BMassage the swollen area firmly to spread the contrast into the tissues
    3. CReinsert the injector line into the same cannula and complete the scan
    4. DElevate the limb, apply a compress and monitor for compartment syndrome
    Show answer and explanation▾

    Answer: D. Elevate the limb, apply a compress and monitor for compartment syndrome

    Contrast extravasation is managed by stopping the injection, elevating the limb, applying cold or warm compresses and monitoring, with urgent surgical review if there is increasing pain, altered perfusion, sensory change or skin blistering. Flushing the cannula or massaging the area forces more fluid into the tissues and can worsen injury.

13. Question 13Specialized Imaging Modalities (CT, MRI, US, Mammography, Nuclear Medicine, Fluoroscopy/Angiography)medium

    On a brain MRI, on which sequence does cerebrospinal fluid normally appear hyperintense (bright)?

    1. AT1-weighted
    2. BFLAIR
    3. CDiffusion-weighted (b = 1000)
    4. DT2-weighted
    Show answer and explanation▾

    Answer: D. T2-weighted

    Fluid has a long T2 relaxation time and therefore appears bright on T2-weighted images. On T1-weighted images CSF is dark, and FLAIR is a T2-weighted sequence with an inversion pulse that specifically suppresses the CSF signal, which is why it is the most tempting distractor.

14. Question 14Specialized Imaging Modalities (CT, MRI, US, Mammography, Nuclear Medicine, Fluoroscopy/Angiography)medium

    Which standard screening mammography projection demonstrates the largest amount of breast tissue, including the upper outer quadrant and axillary tail?

    1. AMediolateral oblique (MLO)
    2. BCraniocaudal (CC)
    3. CTrue lateral (90 degree mediolateral)
    4. DExaggerated craniocaudal (XCCL)
    Show answer and explanation▾

    Answer: A. Mediolateral oblique (MLO)

    The MLO is angled parallel to the pectoralis major, so it includes the most breast tissue, particularly the upper outer quadrant and axillary tail, and should show the pectoral muscle to nipple level. The CC view complements it by showing medial tissue well, but it can miss posterior lateral tissue. The XCCL is a supplementary view, not a standard screening projection.

15. Question 15Infection Control & General/Occupational Safetyeasy

    After imaging a patient with Clostridioides difficile diarrhoea, how should the radiographer clean their hands?

    1. AUse an alcohol-based hand rub
    2. BWash with soap and running water
    3. CUse an alcohol rub twice in a row
    4. DWipe with a dry paper towel
    Show answer and explanation▾

    Answer: B. Wash with soap and running water

    C. difficile forms spores that are resistant to alcohol, so hands must be washed with soap and water, which removes spores mechanically. Alcohol hand rub is suitable for most routine hand hygiene, but it does not reliably remove these spores, even when repeated.

Last reviewed September 2026. Questions are original and written to the published exam blueprint; they are not taken from any real paper.