Dosimetric Verification of Grid Radiotherapy Using Three Ionization Chamber Detectors o Dosimetry


This study aims to provide verification between measured and calculatedradiation dose using three different ionization chamber detectors in Grid plans toselect the best ones To the best of our knowledge, this is the first practicalexperiment in such subject. Grid radiotherapy is an unconventional method forbulky tumors treatment. It is characterized by a single-fraction and high radiationdose. Ten cases (scenarios) were selected to achieve Grid plans by MLCs, with asingle dose of 1500-2000 cGy. Three ionization detectors were employed to measurethe maximum, mean, and point doses (cGy), and match them with those calculatedby the linear accelerator used in this study. The results showed significantdifferences among the three detectors in measuring the maximum and mean doses,with p-value = 0.0016 and 0.06, respectively. While the differences among themeasured three detectors and calculated doses for the point dose were nonsignificant,p = 0.12. The variation in the results of the corresponding percentagebetween calculated and measured doses depended on the type and position of thedetector, the scattering, and the leakage of the radiation. In conclusions, the Semiflexchamber gives the best results.