Reference levels in radiation doses and image quality metrics in chest-abdomen protocols in a neonatal unit

The concept of diagnostic dose reference levels was introduced in diagnostic radiology as a tool to monitor patient dose. It is good practice to assess not only the consistency of the image quality of clinically acceptable X-ray images but also the radiation doses. This study evaluated the reference levels in radiation doses and image quality metrics in chest-abdomen imaging protocols in a neonatal intensive care unit.

X-ray images of the chest-abdomen were decomposed into five frequencies using the Laplacian pyramid. Image quality metrics were derived from the zero and third subbands in the lung-rib space and the mediastinum regions. Skin doses were estimated from the X-ray radiation output characteristic curves of the mobile X-ray units. The local diagnostic reference levels for entrance skin dose and image quality metrics were estimated.

For neonates weighing less than 1000 g, the proposed LDRL was 54.7 μGy, whereas for neonates with weights between 1000 and 1499 g, the LDRL was established as 50.1 μGy. Neonates weighing between 1500 and 2499 g and weighing greater than 2500 g had LDRLs of 50.9 μGy and 55.5 μGy, respectively. The reference levels for image quality metrics of the radiographs for the study population were established as 5.4, 3.4, 6.1, and 4.1 for lung noise, lung detail, mediastinum noise, and mediastinum detail, respectively.

Although radiation doses were comparable to those cited in literature, neonates with weights of 1000-1499 g and 1500-2499 g had skin doses lower than those of neonates with weights below 1000 g.

Weight-based exposure parameters are recommended to ensure that neonatal skin doses are linearly proportional to weight, thereby maintaining adequate image quality across all weight groups and mobile units.