Effective and organ doses for chest-abdomen imaging in neonates: Effects of simulated radiation field size and number of performed X-ray images.

INTRODUCTION: Suboptimal collimation practices during neonatal chest-abdomen imaging may expose organs to unnecessary radiation, while repeated imaging contributes to cumulative radiation dose. This study evaluates the effects of radiation field size and the number of performed X-ray images on effective and organ doses during chest-abdomen X-ray examinations in a neonatal unit. MATERIALS AND METHODS: Exposure parameters and demographic data were collected from 123 neonates who underwent chest-abdomen imaging. Entrance skin air kerma was calculated using radiation output characteristic curves of the mobile X-ray units. Effective and organ doses were estimated using Monte Carlo simulation software based on patient-specific exposure data. RESULTS: The average effective dose for the study population was 0.025 mSv per X-ray image, while the average doses to the thyroid and testicles were 0.042 mGy and 0.056 mGy, respectively. For neonates weighing <1000 g, the average lung dose was 0.033mGy, whereas for neonates with weights between 1000 - 1499 g, 1500 - 2499 g, and greater than 2500 g, the average lung doses were 0.025 mGy, 0.029 mGy, and 0.029 mGy, respectively. Approximately 95% of the X-ray images included body regions outside the intended anatomical area within the primary beam. A strong positive correlation (R = 0.99, p < 0.001) was observed between the effective dose and the total number of X-ray images performed on neonates. DISCUSSION: The results suggest that exposure parameters for neonates weighing <1000 g may not be fully optimised for radiation protection. Slightly elevated thyroid and testicle doses compared with previous studies may be associated with wider radiation field sizes. Increased field size was also associated with higher effective and organ doses. CONCLUSION: Accurate anatomical landmarking and improved collimation practices are essential to minimise unnecessary radiation exposure during neonatal imaging of chest-abdomen to exclude unintended body parts from the primary beam. Exposure parameters should be optimised using weight-based criteria in accordance with the ALARA principle to reduce effective and organ doses across all neonatal weight groups. PLAIN LANGUAGE SUMMARY: Newborn babies who need X-ray examinations can be exposed to extra radiation if areas outside the body part being examined are included in the image. This study analysed chest-abdomen X-rays from 123 newborn babies and estimated radiation doses to different organs using computer-based modelling. This study found that most images included body areas outside the intended region, and radiation dose increased as the number of X-rays and the size of the exposed area increased. This matters because improving image positioning and tailoring exposure settings to a baby's weight may help reduce unnecessary radiation exposure while maintaining the information needed for care.