Abstract:
The purpose of this study is to investigate the relative performance of compact ionization chambers as it changes based on the speed of detector motion and collection volume. To quantify changes, multiple scans were made with each of a selection of compact chambers and repeated varying detector speed. Each scan was then used to compute the necessary statistics for each field sampled. These results were then compared to analyze differences in relative ionization readings across entire scan ranges.
The results and conclusions of this study further reinforce existing studies, in particular those released since 2007 relating to the study of newly available compact ionization chambers. When choosing a chamber, one should use the smallest chamber available that has been proven to respond appropriately for the field sizes to be measured. As for detector speed, generally smaller field sizes are shown to be more sensitive to detector speed changes. There is not one recommendation for detector speed, as the optimum speed is determined by the type of scan being performed, the energy being scanned, the field size being scanned, and the end use of the data being captured. Finally, optimizing pdd scan depths and profile penumbra margins is an important step to maximizing efficient use of time when capturing LINAC beam characteristics.
