Electronic monitoring of radiotherapy fractions using electronic portal imaging device
A number of options exist for detecting errors in radiotherapy treatments, but it has been demonstrated that in vivo dosimetry using the electronic portal imager device (EPID) is among the most effective. Deployment of the EPID beyond the patient allows for the exit dose to be captured. Any change in this exit dose between fractions indicates a potential change in the patient’s treatment. Such a change could be caused by three possibilities: (i) changes in the radiation beam from the machine; (ii) changes in the patient position; or (iii) changes in the patient anatomy. We investigated the sensitivity of a commercial EPID dosimetry system to changes originating from these three sources.