RD7.5 | Imaging in Paediatrics — Graded Quiz — RD7.5 | Imaging in Paediatrics

Q1 RD7.5 1 pt

Children are deliberately imaged with less ionising radiation than adults. Which TWO physiological facts are the principal reasons captured by the 'image gently' / ALARA principle in paediatrics?

A Children have more rapidly dividing cells and a longer remaining lifespan in which a radiation-induced cancer can manifest ✓

B Children have fewer dividing cells and a shorter lifespan, so cumulative dose matters less

C Children's tissues are radioresistant, so higher doses are needed for diagnostic images

D Paediatric organs are larger, requiring proportionally higher radiation exposure

E Radiation risk is identical in children and adults; the difference is purely administrative

Correct. Children have more actively dividing (radiosensitive) cells and a longer life expectancy over which a radiation-induced malignancy can develop, making them more radiosensitive. This underpins ALARA / 'image gently' — prefer USG and MRI and minimise CT.

Paediatric radiosensitivity = rapidly dividing cells + long latency window. ALARA / image gently: prefer USG/MRI, minimise CT and unnecessary radiographs.

Children are MORE radiosensitive than adults because of rapidly dividing cells plus a long remaining lifespan for a cancer to manifest. This is exactly why ALARA / 'image gently' favours USG and MRI over ionising studies.

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Q2 RD7.5 1 pt

A 2-year-old has clinically diagnosed uncomplicated community-acquired pneumonia and is well and feeding. A junior colleague asks why no chest radiograph was ordered. What is the single best justification?

A The diagnosis is clinical and a routine film would not change management, so it only adds radiation ✓

B Chest radiographs are technically too difficult to obtain in toddlers

C A radiograph would be falsely negative in nearly all paediatric pneumonias

D Antibiotics cannot be started until ultrasound has excluded an effusion

E Radiographs are contraindicated in children under 5 years of age

Correct. In uncomplicated clinical pneumonia in a well child the diagnosis is clinical; a routine radiograph does not change management and therefore only adds radiation. Imaging is reserved for deterioration, doubt or suspected complications.

Order imaging only when the result will change management. In a well child with clinical pneumonia, withholding the film is the correct, radiation-sparing decision.

The justification is pedagogically central: uncomplicated pneumonia is a clinical diagnosis, and a routine film changes nothing while adding radiation. Radiographs are neither contraindicated nor uniformly false-negative — they are simply unnecessary here.

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Q3 RD7.5 1 pt

A 3-year-old with confirmed pneumonia develops persistent high fever and a large right pleural collection. Ultrasound shows multiple septations within the fluid. How should these findings most appropriately change management?

A They indicate a complicated, loculated empyema that is unlikely to resolve with antibiotics alone and warrants drainage (± fibrinolytics or surgical referral) ✓

B Septations are a normal finding and require no change in management

C They confirm a simple transudative effusion that will resorb spontaneously

D They mandate immediate contrast-enhanced CT before any intervention can be considered

E They indicate the diagnosis is not infective and antibiotics should be stopped

Correct. Septations on ultrasound indicate a complicated, loculated parapneumonic effusion/empyema unlikely to clear with antibiotics alone — this changes management towards drainage, intrapleural fibrinolytics, or surgical (VATS) referral. USG, not CT, characterises the septations.

USG septations distinguish a complicated/loculated empyema (needs drainage ± fibrinolytics/VATS) from a simple effusion. The imaging finding directly drives the intervention.

Septated pleural fluid on USG = a complicated, loculated empyema. This is precisely the finding that escalates management to drainage ± fibrinolytics or surgery; it is not a normal or simple effusion, and USG (not routine CT) is the modality that reveals it.

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Q4 RD7.5 1 pt

In a child with suspected foreign body aspiration but a cooperative-age limitation, which radiographic technique is most useful to UNMASK air-trapping when a standard inspiratory film looks normal?

A Expiratory (or lateral decubitus) views, which accentuate the failure of the affected lung to deflate ✓

B A penetrated (high-kV) inspiratory film to better visualise the radiolucent object directly

C An apical lordotic view to project the foreign body clear of the clavicles

D A swimmer's view to assess the cervicothoracic junction

E Weight-bearing erect views of both lungs

Correct. Expiratory films — or lateral decubitus views in an uncooperative toddler — accentuate air-trapping: the obstructed lung fails to deflate and stays hyperinflated, with mediastinal shift away. These manoeuvres reveal indirect signs when the standard film is normal.

Expiratory / lateral decubitus views accentuate air-trapping in FB aspiration — the obstructed lung stays inflated when the rest deflates. Essential when the inspiratory film is normal.

Air-trapping is unmasked by expiratory views (or decubitus views in a young child) because the obstructed lung cannot deflate. Lordotic, swimmer's, and penetrated views do not address the ball-valve air-trapping mechanism.

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Q5 RD7.5 1 pt

A 9-month-old infant has had two febrile UTIs and an ultrasound showing a duplex collecting system. The team wants to determine whether the kidneys have suffered cortical damage / scarring after pyelonephritis. Which investigation specifically answers this question?

A DMSA cortical scintigraphy ✓

B Micturating cystourethrogram (MCUG)

C Repeat renal ultrasound alone

D Plain abdominal radiograph (KUB film)

E Doppler ultrasound of the renal arteries

Correct. DMSA scintigraphy is the test for cortical integrity — it detects acute pyelonephritic change and established cortical scarring, and gives differential (split) function. Ultrasound assesses anatomy and MCUG assesses reflux; neither reliably grades cortical scarring.

DMSA = cortex (scarring/pyelonephritis + split function). USG = anatomy; MCUG = reflux. Choose the tool by the exact question being asked.

Cortical scarring/pyelonephritis is answered by DMSA scintigraphy, which also gives split function. Ultrasound is for anatomy and MCUG for reflux — they do not reliably demonstrate cortical scars.

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Q6 RD7.5 1 pt

A 5-year-old child presents with a single, typical, lower-tract UTI (dysuria, frequency) that responds promptly to antibiotics, with no fever and no atypical features. According to age- and risk-based (NICE/ISPN) protocols, what is the most appropriate imaging approach?

A No routine imaging is required for a single typical lower-tract UTI that responds promptly in this age group ✓

B Urgent MCUG to exclude vesicoureteric reflux in all children with any UTI

C DMSA scan during the acute infection to look for scarring

D Contrast-enhanced CT urography to define the anatomy

E Routine ultrasound, MCUG and DMSA for every child after a first UTI regardless of features

Correct. Imaging in paediatric UTI is selective, driven by age and risk. A single typical lower-tract UTI in an older child that responds promptly does not need routine imaging. Younger, febrile (upper-tract), atypical or recurrent UTIs are the ones investigated — sparing radiation and resources.

Image selectively by age and risk: younger, febrile (upper-tract), atypical or recurrent UTIs are imaged; a single typical lower-tract UTI that responds promptly is not.

The principle is selective, risk-based imaging. A single typical lower-tract UTI in an older child that responds promptly needs no routine imaging; investigation is reserved for younger, febrile, atypical or recurrent cases. Imaging everyone wastes radiation and resources.

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