Radiologic imaging of the newborn inside the incubator. Part 2: Radiation dose and image quality

Introduction: Newborn babies in the Neonatal Intensive Care Unit (NICU), especially those born before 37 weeks of gestation, often require many radiological examinations during their first weeks of life. Since the risk of cancer induction by exposure is higher for children than adults, it is crucial to keep the exposure as low as reasonably achievable (ALARA), while maintaining a satisfactory quality of the image. Materials and Methods: In this work, conducted at the NICU of AOU in Cagliari, an optimization study on radiation dose and image quality is performed on three incubators using a test object TOR (CDR) and a neonatal chest phantom (GAMMEX mod.610). In a previous study, attenuation values of the components for the above-mentioned incubators were computed. Using the TOR, low and high contrast sensitivity and spatial resolution are calculated. Radiographs of the phantom are evaluated by a radiologist, on the basis of anatomical features visibility, noise and contrast, using a five-grade scale. Moreover, pathologies simulated with the phantom are diagnosed by the radiologist. Indicators of diagnostic performance such as sensitivity, specificity and odds ratio are evaluated. Incident air Kerma on the phantom (Ka,i)ph and on the incubators plate (Ka,i)p and Entrance Surface Dose (ESD) are calculated for different X-ray exposure parameters and related to the corresponding image quality. Results and Conclusions: Image quality, Ka,i and ESD are calculated and compared for the three incubators under analyses. The different attenuation features of the incubators have a significant influence on the above-mentioned values. Finally, exposure values and incubators configurations for optimizing the images quality and radiation dose are proposed.