Fellowship of the Royal College of Radiologists (FRCR) examinations in clinical radiology Study Guide

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Two sealed sources each contain 4 MBq but emit different radiations. Their transformation rates match, while their external dose rates need not match because radiation energy, shielding and measurement geometry influence exposure.

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A source has an initial activity of 640 MBq and a physical half-life of six hours. After 18 hours, three half-lives have elapsed, leaving 80 MBq when biological clearance is excluded.

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A point-source dose rate is 24 microsieverts per hour at one metre. With unchanged output and negligible scatter, moving to three metres reduces the predicted rate to 24 divided by nine, approximately 2.7 microsieverts per hour.

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Two tissues have equivalent doses of 5 mSv and 2 mSv, with hypothetical supplied tissue factors of 0.12 and 0.04. Their combined effective-dose contribution is 0.60 plus 0.08, giving 0.68 mSv.

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If quantum noise limits an image, doubling mAs improves signal-to-noise ratio by approximately the square root of two. It does not double spatial resolution.

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For a slowly moving target, reduce 15 to 7.5 pulses per second and verify movement visibility and displayed dose information. Retain a higher rate when rapid motion cannot otherwise be followed adequately.

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A patient reports a cardiac device but cannot identify its model. Obtain reliable documentation before determining suitability. Unexpected focal heating during scanning requires stopping and assessing the patient and equipment arrangement.

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Reconstruct one chest acquisition with thin, sharp-kernel lung images and thicker, smooth-kernel mediastinal images. Additional reconstructions from the same acquired data do not themselves require another exposure.

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Choose a high-frequency probe for a superficial tendon and a lower frequency for a poorly penetrated deep target. Compare a calculus producing posterior shadowing with a simple cyst producing increased echoes in tissues beyond it.

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Use suitable fluid-sensitive imaging to assess oedema. Smaller voxels improve spatial detail but reduce signal-to-noise ratio; additional averages improve signal-to-noise ratio at the cost of acquisition time. See the [University of Illinois MRI image-characteristics teaching](https://mri.beckman.illinois.edu/interactive/topics/contents/image_characteristics/index.shtml).

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A routine water image develops a ring artefact. Confirm the setup, document the finding and involve the radiographer and medical physicist for corrective action and assessment of clinical impact.

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In PET/CT, distinguish functional tracer distribution from the anatomical information supplied by CT. Interpret a focus by its location, tracer behaviour and clinical context rather than its brightness alone.

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Before repeating CT, establish what new information is needed and whether existing imaging answers the question. If another acquisition is justified, tailor coverage, phases and technical settings to that task and the patient's characteristics.

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On abdominal imaging, trace a vessel formed by superior mesenteric and splenic venous confluence toward the liver. Identify it as portal inflow, rather than a hepatic vein draining toward the inferior vena cava.

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Identify the duodenum around the pancreatic head, then follow the gland leftward with the splenic vein behind it. Use the mesenteric vessels to distinguish the neck from the uncinate process.

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A thoracic vessel is traced from the right ventricular outflow toward the lungs. Identify pulmonary arterial circulation even though its blood is relatively deoxygenated. A vessel entering the left atrium belongs to pulmonary venous return.

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An arch vessel divides into arteries continuing toward the right neck and right upper limb. Identify the parent as the brachiocephalic trunk, then confirm its branches by following their courses.

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Locate the gland between the cavernous carotid arteries on coronal MRI, then trace the stalk on sagittal imaging. Describe superior extension toward the optic chiasm separately from lateral extension toward a cavernous sinus.

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An opacity in the lingula is a left upper-lobe abnormality, although its position resembles the right middle lobe. Confirm its fissural and bronchial relationships before reporting lobar location. [Manipal's anatomical specimen teaching](https://mapkmc.manipal.edu/specimen/anat239/) demonstrates the lobar bronchial divisions.

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Use the bladder, cervix, endometrial canal and rectum to orient sagittal imaging before deciding whether a mass is uterine, cervical or extrauterine. Follow continuity with the suspected organ of origin.

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Use the bicipital groove to distinguish anterior cuff structures. Include axial images through the acromion to identify the unfused centre and distinguish its interface from the acromioclavicular joint.

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Before using a negative D-dimer to avoid imaging in intermediate probability, confirm that the assay and threshold are validated for that probability group.

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If pulmonary arteries are poorly opacified, report limited assessment rather than excluding embolism. Check a tiny isolated peripheral defect across adjacent sections before accepting it as clot.

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A patient requiring PE imaging has a reason to avoid iodinated contrast. Consider ventilation–perfusion assessment and explain that its components evaluate air distribution and blood flow.

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During assessment of unilateral leg swelling, a proximal deep vein remains noncompressible. Integrate this with visible intraluminal material and flow findings rather than relying on symptoms alone.

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Marked unilateral swelling persists after adequate assessment of accessible leg veins, but pelvic veins were not evaluated. Request appropriately planned CT or MR venography covering the suspected proximal territory.

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A stable patient needs anatomical mapping of suspected arterial disease. Explain that CTA generally uses peripheral intravenous injection, whereas catheter access may be selected when its therapeutic capabilities are required.

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For abrupt severe chest pain, arrange urgent aortic CT when suitable. If a flap involves the ascending aorta, identify type A dissection and communicate urgently.

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An older adult remains unable to bear weight after a fall despite negative radiographs. Use noncontrast MRI if suitable and available, or noncontrast CT when MRI device conditions cannot be verified. Reassess continuing clinical–imaging discordance.

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In chronic weakness with a high-riding humeral head, consider substantial cuff deficiency and use ultrasound or MRI to assess the tendons. Describe the alignment observation separately from the inferred tendon abnormality.

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After a fall, obtain shoulder radiographs to assess alignment and fracture before choosing tendon-focused ultrasound, especially when examination does not isolate a soft-tissue injury.

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Radiographs show no acute bony injury, but examination suggests a cuff tear. Select ultrasound or MRI for tendon assessment instead of assuming normal radiographs have excluded the lesion.

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Persistent shoulder symptoms suggest a labral lesion after initial assessment. Consider MR arthrography and explain that contrast is introduced into the joint rather than simply into a vein.

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Report anterior dislocation and the suspected associated fragment, state any uncertain donor site, and communicate promptly. Recommend post-reduction radiographs to confirm congruity and consider noncontrast CT when fracture definition will change management.

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Begin with ultrasound for suspected gallbladder inflammation. If it does not explain the presentation, select further imaging according to whether the remaining concern involves cystic-duct patency, duct anatomy or another organ.

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Tracer reaches the biliary tree and bowel but the gallbladder remains unseen at one hour. Continue appropriate delayed or augmented imaging before concluding acute cholecystitis.

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Persistent pain, fever and leucocytosis with concern for a hepatic or adjacent inflammatory collection support contrast-enhanced CT. Predominantly cholestatic findings with a duct-mapping question support MRCP.

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Use MRCP for a stable patient's unresolved duct-mapping question. When established obstruction requires endoscopic treatment, ERCP can provide intervention; another MRCP supplies images without relieving it.

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CT shows dilated proximal bowel, a focal calibre change and collapsed distal loops. Describe a mechanical obstruction pattern, localise the transition and assess for a cause and complications.

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Describe two adjacent transition points enclosing a dilated loop when observed. If mural hypoenhancement accompanies the pattern, communicate concern for closed-loop obstruction with possible ischaemia and recommend urgent surgical assessment.

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A nonpregnant adult presents with acute colicky flank pain and no established stone diagnosis. Select noncontrast CT when imaging is indicated rather than automatically requesting contrast-enhanced CT urography.

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Begin with renal and bladder ultrasound for suspected obstruction in pregnancy. If symptoms remain concerning, identify whether further imaging must demonstrate a calculus, establish obstruction or investigate another cause.

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A 24-year-old reports a new focal lump. Arrange targeted ultrasound and correlate the images with the actual palpable finding rather than dismissing it because malignancy is less common at her age.

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A 46-year-old develops a lump after a previous screening examination. Arrange diagnostic mammography or tomosynthesis with appropriate targeted ultrasound rather than waiting for the next screening invitation.

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A firm persistent mass remains suspicious despite normal targeted ultrasound and diagnostic mammography. Arrange further assessment and consideration of biopsy rather than discharge based solely on reassuring imaging.

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A homogeneous 6-HU incidental mass requires no further characterisation imaging under this criterion. A 16-HU lesion needs a different assessment incorporating size, prior imaging, cancer history and endocrine findings.

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In a nonpregnant patient with an incompletely characterised adnexal abnormality, pelvic MRI may clarify origin and tissue characteristics. If concern shifts to appendicitis or another abdominal process, CT may answer that different question.

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Observe and reassess a clinically low-risk child. For a stable child with intermediate risk and focal right lower quadrant symptoms, begin with ultrasound and record whether it gives a definitive answer.

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Poor hepatic extraction with no bowel activity cannot independently establish atresia. Confirmed bowel transit instead demonstrates that tracer can pass through the biliary route into the intestine.

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Persistent focal tenderness after nondiagnostic ultrasound supports MRI or contrast-enhanced CT. When abscess is suspected, select an examination that maps the collection and associated abdominal disease.

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Choose pyloric ultrasound for a five-week-old with repeated forceful nonbilious vomiting and appropriate clinical suspicion. State the age and vomiting pattern so the examination targets the suspected cause.

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A three-week-old develops bilious vomiting. Arrange urgent clinical assessment and an upper gastrointestinal examination for suspected malrotation rather than following the nonbilious pyloric pathway.

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A distal obstructive pattern directs attention to contrast enema. A double bubble with distal gas instead supports upper gastrointestinal assessment of a less complete proximal obstructive pattern.

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An adult develops a severe headache reaching maximum intensity within moments. Choose urgent noncontrast CT rather than delaying for routine outpatient MRI intended for nonacute headache.

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An unchanged established migraine pattern without red flags generally needs no routine scan. Recurrent strictly unilateral attacks with ipsilateral tearing or other cranial autonomic symptoms suggesting cluster headache support MRI without and with contrast.

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Lateral and third ventricular enlargement with a relatively normal fourth ventricle directs attention to the aqueduct and neighbouring structures. Review the suspected obstruction directly rather than relying on ventricular size alone.

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An adult has acquired conductive loss without a clinically evident middle-ear mass. Select dedicated noncontrast temporal bone CT rather than generic contrast-enhanced head CT.

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Audiometry demonstrates unexplained asymmetric sensorineural loss. Choose targeted MRI including the internal auditory canals rather than relying on temporal bone CT alone for a possible retrocochlear cause.

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Twenty-second episodes on rolling in bed, without other neurological symptoms, fit typical BPPV and generally need no scan. Persistent vertigo with unilateral limb dysmetria or new diplopia instead supports urgent central assessment and brain MRI; include targeted internal auditory canal imaging when the question also concerns retrocochlear disease.

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Back pain accompanied by new lower-limb weakness and bladder dysfunction requires urgent clinical evaluation and spinal MRI for suspected neural compression. Communicate significant findings promptly to the team responsible for immediate care.