Repeat Imaging in a 1.1 kg Neonate
You are the radiographer covering a 32-bed level III neonatal unit on the night shift. A baby born at 27 weeks, now 3 weeks old and weighing 1.1 kg, has had a portable chest/abdomen film every morning since admission plus extra films for line checks - 34 exposures so far. The team's request for today reads "babygram - lines and tube." The nursing staff ask you to include the whole trunk from the lung apices to the groin. The unit has one DR portable with a fixed 80 cm source-to-image distance, no automatic collimation, and a vendor exposure-index target of 200–400 for neonatal chest work; the last image logged an EI of 640, while the one before it was 150. The previous film was repeated because the detector was placed too low and cut off the costophrenic angles. The neonatologist is at the bedside and needs the image for a line round in 10 minutes. The baby is stable, on CPAP, with an umbilical line and a percutaneous central line.
1. Field size, positioning and the "babygram" request: what do you do, and why?
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What drives the decision. The clinical question is the position of the umbilical line, the percutaneous central line and possibly the ETT, not "the whole baby." Every extra centimetre of field adds scatter and dose to an infant whose lifetime attributable risk per mGy is far higher than an adult's. A "babygram" is a habit, not an indication.
Field and technique.
- Ask the neonatologist what is being checked: line tip only, or line tip plus lung parenchyma.
- Collimate from the lung apices to the level needed. For an ETT and upper lines, apices to about T10–L1; include the umbilicus only if the umbilical catheter tip is in question. Do not include the groin unless there is a femoral line.
- Use the smallest detector field, 80 cm SID, no grid, and the neonatal technique chart or manual technique. Keep the arms up and hands out of the field.
- Gonadal shielding is not indicated here and would obscure anatomy; it is not a substitute for collimation.
Communication. Say to the nurse: "I will include both line tips and the lung fields; the groin is not needed for these lines and adds dose." If the team insists, ask the neonatologist to document the indication, which turns a habit into a clinical decision.
2. The image is rotated and the ETT tip sits higher than the nurse expected. Do you repeat it, and what do you change if you do?
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Repeat or not? The test is whether the technical deficiency prevents the clinical question from being answered.
- Rotation that still allows the line tip to be seen relative to the trachea, carina and vertebral bodies may not require a repeat.
- An ETT tip the team calls "too high" is a clinical finding, not a positioning failure. The technologist should not repeat in order to change a tube position.
- If the detector cut off the costophrenic angles and the question includes the lung bases or a line in that region, the image is non-diagnostic and a repeat is justified.
If repeating, change something.
- Reposition the detector under the patient rather than moving the patient onto the detector.
- Straighten the trunk, secure the arms, and use tape judiciously.
- Use the same technique, aiming for the middle of the EI target, rather than increasing exposure.
- Record the repeat reason and the dose; one repeat doubles that day's exposure, so it must count. If the baby becomes unstable, stabilize first and image later.
3. What dose-tracking and quality-improvement actions should follow this examination?
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Dose metrics.
- EI is an exposure indicator, not patient dose. Log the EI, technique and DAP where available, and investigate why EI ranged from 150 to 640: technique drift, no AEC, calibration, or detector placement.
- Each exposure should be recorded in the dose registry so cumulative dose can be reviewed.
Practice review.
- 34 exposures in 18 days with extra line checks is a lot. Ask whether the daily film is protocol-driven or habit.
- Propose a standardised neonatal "line check" protocol with one technique chart and a defined field, reviewed with the neonatologist and physicist.
- Audit repeat reasons monthly and feed the results back to the NICU team.
Escalation.
- Flag the EI outlier to the QC lead or physicist and consider a dose audit against a national neonatal benchmark.
- Report the findings to the radiation safety or quality committee, with actions and a review date, so the improvement is sustained rather than a one-night fix.