Evaluation of dose calculations accuracy of a commercial treatment planning system for the head and neck region in radiotherapy.

AIM: The objective was to quantify dose calculation accuracy of TiGRT TPS for head and neck region in radiotherapy.

BACKGROUND: In radiotherapy of head and neck cancers, treatment planning is difficult, due to the complex shape of target volumes and also to spare critical and normal structures. These organs are often very near to the target volumes and have low tolerance to radiation. In this regard, dose calculation accuracy of treatment planning system (TPS) must be high enough.

MATERIALS AND METHODS: Thermoluminescent dosimeter-100 (TLD-100) chips were used within RANDO phantom for dose measurement. TiGRT TPS was also applied for dose calculation. Finally, difference between measured doses ( D meas ) and calculated doses ( D calc ) was obtained to quantify the dose calculation accuracy of the TPS at head and neck region.

RESULTS: For in-field regions, in some points, the TiGRT TPS overestimated the dose compared to the measurements and for other points underestimated the dose. For outside field regions, the TiGRT TPS underestimated the dose compared to the measurements. For most points, the difference values between D calc and D meas for the in-field and outside field regions were less than 5% and 40%, respectively.

CONCLUSIONS: Due to the sensitive structures to radiation in the head and neck region, the dose calculation accuracy of TPSs should be sufficient. According to the results of this study, it is concluded that the accuracy of dose calculation of TiGRT TPS is enough for in-field and out of field regions.