Uncooperative Four-Year-Old with Suspected Inhaled Foreign Body

I would use a paediatric chest technique of approximately 60–65 kVp, 1.2–2 mAs, the shortest exposure time the generator allows, a small focal spot, 180 cm SID and a grid if the child's thickness justifies it. The field should be collimated tightly to the lung fields.

Reasoning:

• High kVp with low mAs gives adequate penetration of the mediastinum while keeping tube output low; in a 16 kg child, unnecessary mAs adds dose without improving the clinical question.
• Short exposure time is the single most useful way to freeze motion in a crying child. A blurred image is more likely to be repeated, which doubles dose.
• 180 cm SID reduces magnification and improves sharpness compared with a short SID.
• Immobilisation: I would place the child in the Pigg-O-Stat in an upright position, arms elevated and chin supported, and use the lateral attachment for the lateral view. The mother should not hold the child because she may be pregnant. If an assistant is essential, the assistant should wear a lead apron and stand behind a screen where possible.
• Shielding: I would not place a gonadal shield over the lower chest because it may obscure the lower lung fields; tight collimation is the better protection.
• Before exposure: I would use distraction, counting or a brief pause in crying, and check positioning through the transparent immobiliser so that the repeat is likely to be diagnostic.

I would not automatically repeat the PA for minor rotation. The decision depends on whether the rotation obscures the structures needed to answer the clinical question: the trachea, main bronchi, lung fields and cardiac silhouette.

Reasoning:

• If the rotation is slight and the trachea and main bronchi are visible, the image is likely to be clinically acceptable. Repeating for cosmetic straightness exposes a 4-year-old to extra radiation without diagnostic gain.
• ALARA requires that each repeat be justified by a real deficiency, not by an idealised image. The first exposure was repeated for motion and obscuration; a third exposure needs a clear indication.
• If rotation seriously overlaps the hilar region or hides a suspected foreign body, a limited repeat with tight collimation is justified. I would record the reason in the reject log and note the number of exposures.
• A normal radiograph does not exclude a non-radiopaque foreign body, so the paediatrician should be told that the images are technically acceptable but that clinical follow-up is still needed.
• If I were uncertain, I would consult the radiologist rather than expose the child again.

I would speak to the mother privately and respectfully: explain that because she may be pregnant, she should not hold the child during the exposure. I would reassure her that the Pigg-O-Stat is designed for this purpose and that the child can still be examined safely.

I would then:

• Offer her a lead apron if she wishes to stay nearby, but keep her out of the primary beam and preferably behind the control screen.
• Advise her to tell her own doctor about the possible pregnancy and to take a pregnancy test if appropriate.
• Avoid disclosing her possible pregnancy to other patients or unrelated staff; only share it with staff who need to know for radiation-protection reasons.
• Document in the child's record that the mother reported a possible pregnancy, that she was excluded from immobilisation, and that the Pigg-O-Stat was used. This protects both the patient and the department and shows that the ALARA decision was deliberate.
• If the mother insists on holding the child, I would explain the risk again and offer an alternative trained assistant; I would not simply proceed without documenting the discussion.