A patient dose verification program using diode detectors.

In this work, we present a comprehensive patient dose verification program using a commercial dual diode detector system for external photon beam radiotherapy. To achieve acceptable accuracy, factors potentially affecting diode sensitivity need to be carefully considered in dose determination. Several authors have shown that diode sensitivity depends on temperature, saturation, linearity, radiation damage, and beam incidence angle. In addition, we found that the use of wedge filters, block trays at a close distance to the detectors, variation in radiation field size, as well as measurement SSDs may affect diode sensitivity significantly. In practice, we use a 5% dose deviation of measured dose from expected patient dose to prompt reevaluation of patient dosimetry. This yields a 90% acceptance rate in clinical patient cases.