Characteristics of X-ray attenuation in electrospun bismuth oxide/polylactic acid nanofibre mats.

The characteristics of the X-ray attenuation in electrospun nano(n)- and micro(m)-Bi2O3/polylactic acid (PLA) nanofibre mats with different Bi2O3 loadings were compared as a function of energy using mammography (i.e. tube voltages of 22-49 kV) and X-ray absorption spectroscopy (XAS) (7-20 keV). Results indicate that X-ray attenuation by electrospun n-Bi2O3/PLA nanofibre mats is distinctly higher than that of m-Bi2O3/PLA nanofibre mats at all energies investigated. In addition, with increasing filler loading (n-Bi2O3 or m-Bi2O3), the porosity of the nanofibre mats decreased, thus increasing the X-ray attenuation, except for the sample containing 38 wt% Bi2O3 (the highest loading in the present study). The latter showed higher porosity, with some beads formed, thus resulting in a sudden decrease in the X-ray attenuation.

Suitability of radiochromic films for dosimetry of very-low energy X-rays.

This study examined the response characteristics of three commercially available radiochromic films when exposed to low energy (50 kVp) X-rays. The aim was to evaluate the films for potential use in 2D dosimetry for a low-kV intraoperative radiotherapy (IORT) device known as the 'Intrabeam'. Dose-response relationships were obtained for Gafchromic EBT, XR-RV2, and XR-QA film in water at several distances from the Intrabeam device. It was found that the dose rates from the source were excessive for use of the XR-QA film, and that all three film types showed significant energy dependence within the limits of measurement uncertainty. Basic modeling of primary X-ray spectra indicated large changes in the lower energy components with distance from the source, and it is hypothesized that the changes in film response are a result of changes in film energy response. This is in contrast to previous studies indicating less or negligible energy response. All films showed non-linearity in response over the ranges examined. These results imply significant limitations for the use of these films for low-kV dosimetry.