Dosimetric evaluation of the dose calculation accuracy of different algorithms for two different treatment techniques during whole breast irradiation

Abstract

Objective In-field, partially in-field, and out-of-field organ doses calculated by the Acuros XB (AXB) and analytical anisotropic algorithm (AAA) were compared with experimentally measured data for two different techniques of whole breast radiotherapy (WBRT). Methods The field-in-field conformal radiotherapy (FIF) and intensity-modulated radiation therapy (IMRT) plans were calculated by AAA and dose-to-water (Dw) and dose-to-medium (Dm) options used by AXB. In field (planning target volume (PTV)), partially in-field (ipsilateral lung, heart, left ascending coronary artery (LAD)), and out-of-field (contralateral lung and contralateral breast) organ at risk (OAR) doses were measured using thermoluminescent dosimeters (TLDs) and EBT3 films in an anthropomorphic phantom. Furthermore, target dose differences between AAA and AXB were analyzed for the corresponding real patients. Results For the verification of planar dose distribution in PTV, the percentages of pixels that passed the gamma analysis with the +/- 3%/3mm criteria were 93.5%, 93.9%, and 99.0% for AAA, AXB_Dm, and AXB_Dw, respectively, averaged over all IMRT and FIF plans. For the verification of point doses within the target using TLD in the randophantom, the max percentage deviations between the calculated and measured data when averaged over all IMRT and FIF plans were 6.8%, 4.7%, and 3.9% for AAA, AXB_Dm, and AXB_Dw, respectively. Conclusion When using the Eclipse TPS for breast cancer, AXB should be used instead of the AAA algorithm, bearing in mind that the AXB may still overestimate all OARs doses.