Customization of a radiation management system to support in vivo patient dosimetry using diodes

Considerable effort is generally made in the quality control of radiation therapy units and in patient chart checking to ensure accurate delivery of treatment to the patients. Record and verify (RV) systems have been implemented which will inhibit the beam from being turned ON if the parameters set on the medical linear accelerators do not match a preprogrammed file. It should be emphasized, however, that RV systems are designed only to ensure proper setup of parameters on the therapy units and bear no direct link with proper patient position. The only real link between treatment planning and delivery to the patient is in-vivo dosimetry. Diodes provide a convenient way of measuring the dose received by the patient in real time and, after the initial tedious calibrations, require very little additional effort. In order to facilitate diode use by the therapists in our institution, the radiation management system (RMS) database in use with our linear accelerators was interfaced with the output obtained from a commercially available diode dosimetry system. The chart printout format was altered to read this value from the RMS database allowing a near real-time recording of the actual dose received by the patient for up to three sites concurrently. This provides for an immediate additional check to the planned and received doses already recorded by the RMS RV software. This procedure, if carried out during the first treatment and subsequently on a weekly basis, would ensure that differences of the order of 5% or larger between planned and delivered dose would not go undetected.