Clinical implications of Eclipse analytical anisotropic algorithm and Acuros XB algorithm for the treatment of lung cancer

The aim of the present study was to investigate the dose-volume variations of planning target volume (PTV) and organs at risks (OARs) in 15 left lung cancer patients comparing analytical anisotropic algorithm (AAA) versus Acuros XB algorithm. Originally, all plans were created using AAA with a template of dose constraints and optimization parameters, and the patients were treated using intensity modulated radiotherapy. In addition, another set of plans was created by performing only dose calculations using Acuros algorithm without doing any reoptimization. Thereby, in both set of plans, the entire plan parameters, namely, beam angle, beam weight, number of beams, prescribed dose, normalization point, region of interest constraints, number of monitor units, and plan optimization were kept constant. The evaluated plan parameters were PTV coverage at dose at 95% volume (TV95) of PTV (D95), the dose at 5% of PTV (D5), maximum dose (D(max)), the mean dose (D(mean)), the percent volume receiving 5 Gy (V5), 20 Gy (V20), 30 Gy (V30) of normal lung at risk (left lung- gross target volume [GTV], the dose at 33% volume (D33), at 67% volume (D67), and the D(mean) (Gy) of the heart, the D(max) of the spinal cord. Furthermore, homogeneity index (HI) and conformity index were evaluated to check the quality of the plans. Significant statistical differences between the two algorithms, P < 0.05, were found in D95, D(max), TV95, and HI of PTV. Furthermore, significant statistical differences were found in the dose parameters for the OARs, namely, V5, V20, and V30 of left lung-GTV, right lung (D(mean)), D33, and D(mean) of the heart, and D(max) of the spine, respectively. Although statistical differences do exist, the magnitude of the differences is too small to cause any clinically observable effect.