Title: 192 Neonatal Radiography: Radiation Dose in Association with Image Quality
Abstract: Background/Aims: Premature or seriously ill neonates, often undergo a considerable number of radiographic examinations during their stay in the Neonatal Intensive Care Unit. The increased radiosensitivity of neonates due to the highly mitotic state of their cells in conjunction with longer life expectancy, increase the risk of radiation induced cancer. This highlights the importance of minimising radiation dose, while maintaining satisfactory image quality. An optimisation study concerning radiation dose and image quality in neonatal radiography is presented. Methods: Neonates were categorised into 4 groups, according to birth weight (<1000g, 1000–1499g, 1500–2499g, >2500g). For a total of 190 chest and chest-abdomen radiographs, exposure parameters (tube voltage-kVp, product of tube current and exposure time-mAs, field size) were recorded. Entrance surface dose (ESD) was estimated and Dose-Area product (DAP) was measured directly. Assessment of image quality was performed blindly by two independent observers (a radiologist and a paediatrician) based on the visibility of certain anatomical features and catheters, using a 5-grade scale. Results: ESD values increased with neonatal weight and demonstrated a wide variation, ranging from 15.2 to 60.3microGy (mean 31.6microGy). A wide variation was also observed in DAP values (0.23–0.92microGym2, mean 0.41microGym2). Evaluation of image quality revealed the feasibility to achieve satisfactory image quality (total image quality score >70%) using both high and low kVp techniques. Higher tube voltage techniques resulted in lower ESD values due to the increased beam penetration and the decreased mAs applied. Conclusions: The majority (98.5%) of ESD values are in accordance with the reference level of 50microGy recommended by the National Radiological Protection Board. However, results advocate that the use of high kVp techniques could result to further reduction in radiation dose, without degradation of image quality. Wide dose variations highlight the need of establishing standard examination protocols for neonatal radiography, with respect to weight.