Development and evaluation of QA software for the monitor chamber of an accelerator

The monitor chamber of a radiotherapy system needs to be calibrated once a week. Because the calibration procedure requires a large variety of complicated calculations, we have developed software that facilitates calculation and enables comparison and storage of data. According to the standard measurement of absorbed dose, we used Visual Basic 6.0 (Microsoft Corp.) to establish the calibration method. This new technique has simplified the conventional intricate calculation required for calibration of the monitor chamber and enabled automatic processing of calculated results. We have confirmed the usefulness of this software in calibrating the monitor chamber. In the routine inspection, we can compare the current data with former results. Because of this advantage, it is possible to eliminate serious accidents such as overdosing and underdosing.