Avaliação de algoritmos de cálculo Acuros XB(AXB) e AAA (anisotropic analytical algorithm) para feixes de fótons em planejamentos hipofracionados de mama

Abstract

The objective of this study was to compare the Acuros XB algorithms with the AAA algorithm, visualizing its dosimetric impact in both treatment volumes and Organ On Risk (OAR), especially those involving pulmonary heterogeneities. Several strategies were used to evaluate the characteristics of treatment planning, HF (Conformity Index) and IH (Homogeneity Index), in addition to the dose distribution with V95% and V107% for PTV and PTV increase, both regulatory values. accepted in 3D clinical treatment plans. In relation to the risk organs, the evaluations were made observing the reference values for conformational and hypofractionated treatments, proposed by QUANTEC and RTOG 1005. Two methodologies were used (UM constant and re-optimization) for evaluations, treatment plans were elaborated based on twenty tomographic studies of female patients with left breast cancer, opposing tangential fields in the field in field technique, as well as 6MV and 10MV and semi-tangential photons in integrated reinforcement fields with a 45º or 60º dynamic filter were also used.For a constant, V107% in the PTV breast where AAA underestimates in -7.52% and AAA SC in -18.71%. In the OAR evaluations, between AAA and the Acuros XB algorithm the difference was 1.62% for V5Gy, with AAA being supportive of the dose. While for AAA SCH the percentage difference underestimates by -18.67 The evaluation metrics, in this methodology, mean dose in the cardiac region, AAA presents 2.14% and AAA SCH 3.30% in relation to Acuros XB, overestimating the dose for this metric. Regarding the skin delimited region, the mean dose for AAA presented -5.54% and AAA-SCH-11.70%, underestimating the dose in relation to Acuros XB.The greatest difference was observed for V107%, in the comparison of AAA SCH with Acuros XB of 34.32%, and for AAA where the value found was 13.34%, overestimating the dose in relation to the reference. For clinical evaluation metric, mean dose in the cardiac region, AAA presented 2.20% and AAA SCH 5.70% in relation to Acuros XB, overestimating the dose for this metric. Regarding the contralateral breast, at maximum dose, AAA presented -8.17% and AAA-SCH -12.73% dose relative to reference. Regarding the delimited skin region, the mean dose for AAA presents -4.54% and AAA-SCH -8.50%, underestimating the dose in relation to Acuros XB.It was observed values of UM that in a very relevant way, where we find a difference of 2.0 UM between AAA-R and Acuros XB and 6,6 UM for AAA-R SCH and the same reference in external tangents, we also find an important difference between the one of the algorithms, for the boost fields, in the boost 2 field for AAA-R -2.4 UM and for AAA-R SCH -7,1UM, both compared to Acuros XB.In clinical transitions from one algorithm to another, these should be accompanied by studies and simulations in planning systems, before considering clinical implementation