Veille documentaire MTPH

Auteur     J P McCaffrey
Auteur     F Tessier
Auteur     H Shen
Résumé     PURPOSE To measure the attenuation effectiveness and minimize the weight of new non-Pb radiation shielding materials used for radiation protection by interventional radiology (IR) physicians, to compare the accuracy of the different standard measurement geometries of these materials, and to determine x-ray qualities that correspond to the scattered radiation that IR physicians typically encounter. METHODS Radiation attenuation capabilities of non-Pb materials were investigated. Typically, most studies of non-Pb materials have focused on the attenuating properties of metal powders. In this study, layers of materials incorporating non-Pb powdered compounds such as Bi(2)O(3), Gd(2)O(3), and BaSO(4) were measured individually, as bilayers, and as a Bi(2)O(3)-loaded hand cream. Attenuation measurements were performed in narrow-beam (fluorescence excluded) and broad beam (fluorescence included) geometries, demonstrating that these different geometries provided significantly different results. The Monte Carlo (MC) program EGSnrc was used to calculate the resulting spectra after attenuation by radiation shielding materials, and scattered x-ray spectra after 90° scattering of eight ASTM Standard primary x-ray beams. Surrogate x-ray qualities that corresponded to these scattered spectra were tabulated. RESULTS Radiation shielding materials incorporating Bi(2)O(3) were found to provide equivalent or superior attenuation compared with commercial Pb-based and non-Pb materials across the 60-130 kVp energy range. Measurements were made for single layers of the Bi(2)O(3) compound and for bilayers where the ordering was low atomic number (Z) layer closest to x-ray source∕high Z (Bi(2)O(3)) layer farthest from the x-ray source. Narrow-beam Standard test methods which do not include the contribution from fluorescence overestimated the attenuating capabilities of Pb and non-Pb materials. Measurements of a newly developed, quick-drying, and easily removable Bi(2)O(3)-loaded hand cream demonstrated better attenuation capabilities than commercial Bi(2)O(3)-loaded gloves. Scattered radiation measurements and MC simulations illustrated that the spectra resulting from 90° scattering of primary x-ray beam qualities can be approximated by surrogate x-ray qualities which are more representative of the radiation actually encountered by IR physicians. A table of surrogate qualities of the eight ASTM F2547-06 Standard qualities was compiled. CONCLUSIONS New non-Pb compound materials, particularly single layers or bilayers incorporating Bi(2)O(3), can reduce the weight of radiation protection materials while providing equivalent or better protection compared to Pb-based materials. Attenuation measurements in geometries that exclude the contribution from fluorescence substantially underestimate the quantity of transmitted radiation. A new Bi(2)O(3)-loaded hand cream demonstrated a novel and effective approach for hand protection. Standard testing protocols for radiation protection materials used by IR physicians specify a wider kVp range than is necessary. A more realistic range would acknowledge the lower kVp resulting from scatter and allow IR physicians to confidently utilize lighter-weight materials while still receiving adequate protection. Standards protocols incorporating the adjustments described in this work would maintain the safety of IR personnel and lessen the physical repercussions of long hours wearing unnecessarily heavy radiation protection garments.
Publication     Medical physics
Volume     39
Numéro     7
Pages     4537-4546
Date     Jul 2012