Radiation shielding assessment for interventional radiology personnel: Geant4 dosimetry of lead-free compositions.

The inherent biological hazards associated with ionizing radiation necessitate the implementation of effective shielding measures, particularly in medical applications. Interventional radiology, in particular, poses a unique challenge as it often exposes medical personnel to prolonged periods of high x-ray doses. Historically, lead and lead-based compounds have been the primary materials employed for shielding against photons. However, the drawbacks of lead, including its substantial weight causing personnel's inflexibility and its toxicity, have raised concerns regarding its long-term impact on both human health and the environment. Barium tantalate has emerged as a promising alternative, due to its unique attenuation properties against low-energy x-rays, specifically targeting the weak absorption area of lead. In the present study, we employ the Geant4 Monte Carlo simulation tool to investigate various formulations of barium tantalate doped with rare earth elements. The aim is to identify the optimal composition for shielding x-rays in the context of interventional radiology. To achieve this, we employ a reference x-ray spectrum typical of interventional radiology procedures, with energies extending up to 90 keV, within a carefully designed simulation setup. Our primary performance indicator is the reduction in air kerma transmission. Furthermore, we assess the absorbed doses to critical organs at risk within a standard human body phantom protected by the shield. Our results demonstrate that specific concentrations of the examined rare earth impurities can enhance the shielding performance of barium tantalate. To mitigate x-ray exposure in interventional radiology, our analysis reveals that the most effective shielding performance is achieved when using barium tantalate compositions containing 15% Erbium or 10% Samarium by weight. These findings suggest the possibility of developing lead-free shielding solutions or apron for interventional radiology personnel, offering a remarkable reduction in weight (exceeding 30%) while maintaining shielding performance at levels comparable to traditional lead-based materials.

Doped silica fibre thermoluminescence measurements of radiation dose in the use of 223Ra.

Using tailor-made sub-mm dimension doped-silica fibres, thermoluminescent dosimetric studies have been performed for α-emitting sources of 223RaCl2 (the basis of the Bayer Healthcare product Xofigo®). The use of 223RaCl2 in the palliative treatment of bone metastases resulting from late-stage castration-resistant prostate cancer focuses on its favourable uptake in metabolically active bone metastases. Such treatment benefits from the high linear energy transfer (LET) and associated short path length (<100µm) of the α-particles emitted by 223Ra and its decay progeny. In seeking to provide for in vitro dosimetry of the α-particles originating from the 223Ra decay series, investigation has been made of the TL yield of various forms of Ge-doped SiO2 fibres, including photonic crystal fibre (PCF) collapsed, PCF uncollapsed, flat and single-mode fibres. Irradiations of the fibres were performed at the UK National Physical Laboratory (NPL). Notable features are the considerable sensitivity of the dosimeters and an effective atomic number Zeff approaching that of bone, the glass fibres offering the added advantage of being able to be placed directly into liquid. The outcome of present research is expected to inform development of doped fibre dosimeters of versatile utility, including for applications as detailed herein.