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RD5.1-4 | Core Image Interpretation Skills — Graded Quiz
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When applying the five radiographic densities to interpret a plain film, which sequence lists them correctly from DARKEST (most lucent) to BRIGHTEST (most opaque)?
Correct. The five radiographic densities from darkest/most lucent to brightest/most opaque are air, fat, soft tissue (water), bone (calcium) and metal. Knowing this order underlies every normal read and prevents density-based errors.
Five radiographic densities (lucent → opaque): air, fat, soft tissue/water, bone, metal.
The five densities, darkest to brightest, are: air, fat, soft tissue/water, bone (calcium), metal. Re-anchor this order — it underpins all radiographic interpretation.
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A frontal chest radiograph shows loss of the normal sharp right heart border, but the right hemidiaphragm remains crisply outlined. Using the silhouette sign, which structure is most likely abnormal?
Correct. The silhouette sign: an opacity that obliterates a border lies in anatomical contact with it. Loss of the right heart border (with a preserved diaphragm) localises disease to the right middle lobe, which lies against that border.
Silhouette sign: an opacity erasing a border is in anatomical contact with it — lost right heart border = right middle lobe; lost right hemidiaphragm = right lower lobe.
Apply the silhouette sign: loss of the right heart border localises to the right middle lobe (in contact with that border). Loss of the right hemidiaphragm outline would instead point to the right lower lobe.
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Which step is the correct FIRST action in a disciplined systematic read of any plain radiograph, before searching for pathology?
Correct. A systematic read always starts with demographics and technical adequacy — patient identity, date, and the projection/adequacy — because every downstream judgement (e.g. CTR, free air) depends on the projection being known.
Start every read with identity, date and technical adequacy (projection/adequacy) before searching for pathology.
Begin with identity, date and technical adequacy (including projection). Many interpretive rules (CTR, free air) are projection-dependent, so this must be confirmed first.
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A radiologist must estimate age in a late adolescent (around 16-19 years) in whom the hand-wrist is already mature. Which region is the MOST appropriate to assess next, because its fusion occurs later?
Correct. The central skill is matching the method to the subject's age band. Once the hand-wrist is mature, later-fusing centres such as the medial (sternal) end of the clavicle are used to extend age estimation into late adolescence/early adulthood.
Match the age-estimation method to the age band: hand-wrist for children/early adolescence; the late-fusing medial clavicular epiphysis for late adolescence/early adulthood.
When the hand-wrist is already mature, choose a later-fusing centre. The medial clavicular epiphysis fuses late and is the appropriate choice for late-adolescent age estimation; carpal/phalangeal centres mature earlier.
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A reported bone age in a child is markedly DELAYED relative to a reliably documented chronological age. Which of the following is a recognised cause of this delay?
Correct. Bone age can LAG chronological age in constitutional delay, hypothyroidism and chronic illness/malnutrition. Conditions that accelerate maturation (precocious puberty, androgen excess) instead make bone age LEAD chronological age.
Bone age can lag (constitutional delay, hypothyroidism, chronic illness) or lead (precocious puberty) chronological age — always report a range, never a single year.
Bone age lags in hypothyroidism, constitutional delay and chronic illness. The other options (precocious puberty, androgen excess) accelerate maturation, making bone age lead — not lag.
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A supine abdominal radiograph in a patient with distension shows dilated central bowel loops bearing complete transverse lines (valvulae conniventes) that cross the FULL width of the lumen. What does this most likely indicate?
Correct. Valvulae conniventes (plicae circulares) cross the FULL width of the lumen and are central — features of dilated SMALL bowel. Large bowel shows haustra, which only partially cross the lumen and lie peripherally.
SBO: central loops, valvulae conniventes cross the full lumen. LBO: peripheral loops, haustra cross only part of the lumen.
Valvulae conniventes crossing the full lumen, centrally placed = small bowel obstruction. Haustra (partial, peripheral) characterise large bowel. This is not free air or a normal pattern.
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An erect abdominal/chest series is unavailable in an immobile trauma patient, yet pneumoperitoneum is clinically suspected. On the SUPINE abdominal film, which sign would support free intraperitoneal air?
Correct. On a supine film free air may not rise under the diaphragm, but the Rigler (double-wall) sign — gas on both the luminal and serosal sides of the bowel wall — indicates pneumoperitoneum. The sub-diaphragmatic crescent is the erect-film sign.
Pneumoperitoneum: sub-diaphragmatic crescent on erect CXR; Rigler (double-wall) sign on supine AXR. A negative supine film does not exclude free air.
On a supine AXR look for the Rigler (double-wall) sign for free air. The sub-diaphragmatic crescent needs an erect/horizontal-beam film; valvulae conniventes and haustra are obstruction features, not free-air signs.
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On a portable AP chest film after central venous catheter (CVC) insertion via the right internal jugular vein, where should the catheter tip ideally lie, and what mandatory check must accompany every post-insertion film?
Correct. A CVC tip should sit at the cavoatrial junction (lower SVC). Every post-line film mandates a search for a procedure-related pneumothorax. The ~3-5 cm above carina target is for the ET tube, and a below-diaphragm midline position is for the NG tube.
CVC tip = cavoatrial junction/lower SVC; ET tube = ~3-5 cm above carina; NG tube below diaphragm, midline. Every post-line film: mandatory pneumothorax check.
CVC tip target = cavoatrial junction/lower SVC, and a mandatory post-line pneumothorax check is required. The carina-relative target is for the ET tube; the below-diaphragm midline position is the NG tube.
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