Dosimetric evaluation of alanine-in-glass dosimeters at clinical dose levels using high-energy X-rays from a linear accelerator

This study presents the first dosimetric evaluation of the alanine-in-glass dosimeter in radiation therapy. The dosimeter is composed of a Pyrex glass tube filled with pure polycrystalline alanine. 6 MV X-ray beams from a linear accelerator were used to irradiate the dosimeter in a solid water phantom to therapy-level doses ranging from 0 to 30 Gy. An X-band electron paramagnetic resonance (EPR) spectrometer was utilized to measure the absorbed dose of the dosimeter. The doses measured by the dosimeter were compared to those from ion chamber dosimetry. It was found that the dosimeter exhibited a linear response in the dose range from 0.1 to 30 Gy. The deviation between measured and delivered doses was 0.11% over the 0.5-30 Gy range, whereas the deviation increased to about 25% at 0.1 Gy. The lowest detectable dose with an acceptable deviation limit of 5% or less was found to be 0.3 Gy. The inaccuracy in measurements at low doses can be attributed to background signals and instrument noise. The accuracy can be improved by proper selection of measurement conditions and better optimization of equipment. The findings of this study show that the alanine-in-glass dosimeter is suitable for dose measurements with acceptable accuracy down to 0.3 Gy. The dosimeter is therefore has the potential to be employed in radiotherapy applications and quality control procedures.