Improvement of dose uniformity using a backscatter plate in a single X-ray source for blood irradiator: Monte Carlo simulation approach

Abstract

X-ray irradiators are used to inactivate T-cell function to prevent the risk of transfusion-associated graft-versus-host disease (TA-GVHD). Absorbed dose of 25–50 Gy within 5 min with a dose uniformity ratio (DUR) below 1.5 are recommended for inactivating T cells while sparing other blood components. In this study, different backscatter plate materials were utilized to improve dose uniformity within the entire blood phantom for a single X-ray blood irradiator using Monte Carlo simulation (MCNP6). Based on the simulation results, Be, acrylic, and Al were selected as backscatter plates for their high backscatter ratios. Dose uniformity across the entire blood phantom improved by 29.56%, 21.43%, and 10.44% when using 10 cm Be, 10 cm acrylic, and 4 cm Al as backscatter plates, respectively. Using a backscatter plate improved dose uniformity across the entire blood phantom hence improving blood irradiation efficiency. However, DUR exceeding 1.5 is due to substantial dose difference between the surface and bottom regions of the blood phantom. In future studies, additional filters will be explored to improve DUR and achieve the recommended value.