Reduction of Radiation Dose and Relative Risk of Cancer Induction to Neonates Receiving Anterior-Posterior Chest X-Rays
Background: Chest anterior-posterior (AP) x-ray imaging is used to diagnose and follow up conditions of the heart and lungs in neonates. As neonates are more sensitive to radiation and have longer life expectancies ionizing radiation may increase the risk of cancer induction in this patient population. By using a computed radiography (CR) system acceptable images, requiring lower doses of radiation, may be produced digitally. However, radiation dose reduction is often associated with reduced image quality. Objectives: To derive exposure protocols that decrease the entrance surface dose (ESD) and relative cancer induction risk, while maintaining acceptable visual image quality. Methods and materials: A phantom was designed and used to experimentally optimise x-ray imaging protocols by varying exposure technique factors, such astube voltage and current, exposure time and filtration. Images were ranked according to measured ESDs, visual image quality and relative cancer induction risks. Results: Comparison of derived protocols to a standard neonatal chest exposure protocol revealed that the ESD was reduced approximately by 63% while image quality was improved by about 27%. Relative cancer induction risk analysis showed that, despite reduced ESDs, the risk could be greater than the standard exposure risk. Conclusion: Six exposure options that answer the aim were derived. The most optimal combination of decrease in the ESD and relative cancer induction risk with maintenance of visual image quality is a processed image at 57 kV, 2 mAs, 100 cm focus-to-film distance (FFD), fine focus, tight collimation and 0.1 mm Cu (copper) and 1 mm Al (aluminium) additional filtration.
