Dosimetric evaluation of two radiotherapy treatment planning systems using report 55 by the AAPM task group 23

The AAPM Report 55 of Task Group 23 (TG23) is used to verify the accuracy of the calculation algorithm of two radiotherapic treatment planning systems (TPS), which use two pencil beam models (one of the last generation) and a collapsed cone convolution model. The basic feature of TG23 is that it compares dose values computed by TPS and experimental dose measures in situations that reproduce those of simple radiotherapeutic treatments. A threshold of 2% was considered for discrepancies between computed and measured values. The results gave a good accuracy of considered algorithms, except for those points in high dose gradient regions, for which the evaluation as a percentage difference, rather than in millimeters, may overestimate the discrepancies. It was seen that the TG23 package is not only an algorithm verification method, but also a useful instrument for training with dosimetry, configuration and application of a TPS.