A comparison of the radiation exposure to the left anterior descending artery (LAD) and left ventricle (LV) was performed for twenty-three left breast cancer patients. For each participant, two tangential fields 3D-CRT, two- and seven-field IMRT and two and four partial arcs VMAT plans were created. Dose constraints for CTV, ipsilateral lung and heart were followed. The V_40Gy, V_30Gy, D_av of LAD and V_23Gy, V_5Gy, D_av of LV were calculated and extracted from the plans. Parametric and non-parametric tests were applied to compare the parameters derived from the five treatment techniques. All generated plans fulfilled the dose constraints. The D_av ranges of the LAD and LV from all examined techniques were 11.77–14.73 Gy and 5.37–6.40 Gy, respectively. The V_40Gy and V_30Gy ranges of the LAD were 2.90–12.91% and 10.80–18.51%, respectively. The V_23Gy and V_5Gy of the LV were 4.29–7.43% and 18.24–30.05%, respectively. The VMAT plans and seven-field IMRT significantly reduced the V_40Gy, V_30Gy of LAD and V_23Gy of LV compared with the two-field treatments (p < 0.05). However, 3D-CRT plans provided statistically lower values for V_5Gy of LV over the other techniques (p < 0.05). The presented results provide a detailed dataset of the radiation burden of two critical cardiac structures from five radiotherapy techniques.

Objectives: To evaluate the effectiveness of different optimization parameters on radiotherapy plan quality for seventeen head and neck cancer patients. Methods: Volumetric Modulated Arc Therapy with Simultaneous Integrated Boost (VMAT-SIB) plans, involving up to three tumors, were generated. For each participant, a reference plan (Plan_Ref) was created using dual-arc with 180 control points, 20° gantry-angle increment and 1 cm minimum segment width. Modified plans were developed with dose constraints and optimization settings constant by changing to single-arc, 150 and 200 control points, 0.5 cm minimum segment width, and 30° and 40° gantry-angle increments. These plans were referred to as Plan_Arc1, Plan_CP150, Plan_CP200, Plan_SW0.5, Plan_Inc30, and Plan_Inc40, respectively. D_95% of planning target volumes (PTVs), homogeneity index (HI), monitor units (MUs), maximum dose (D_max) of spinal cord, mandible, and brainstem were recorded. Statistical and Bland–Altman analysis was performed comparing the modified plans to Plan_Ref. Results: Average D_95% values for PTV1, PTV2, and PTV3 ranged from 93.13 to 98.82%. Plan_SW0.5 provided superior target coverage and homogeneity with higher MUs than Plan_Ref. Plan_Arc1 significantly reduced PTV coverage and dose homogeneity, while increasing MUs compared with Plan_Ref (p < 0.05). The average D_max as derived from all planning approaches was up to 43.86 Gy, 65.86 Gy, and 48.85 Gy for spinal cord, mandible and brainstem, respectively. For spinal cord, Plan_Ref led to significantly lower doses compared to Plan_Arc1 and Plan_Inc30, while the brainstem recorded statistically higher D_max doses than Plan_Arc1. Significantly higher D_max was observed for the mandible using Plan_SW0.5 (p < 0.05). However, for D_max, the comparison plans showed good agreement with Plan_Ref based on Bland–Altman analysis. Conclusions: The VMAT plan quality is strongly affected by the minimum segment width whereas no differences were observed with the modification of the number of control points.