Comparative Dosimetric Study of Intensity-modulated Radiotherapy and Volumetric-modulated Arc Therapy Techniques with Hypofractionated Intensity-modulated Radiotherapy after Modified Radical Mastectomy for Breast Cancer

Abstract Background This study aimed to compare the advantages and disadvantages of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT), in left-sided breast cancer patients who underwent hypofractionated intensity-modulated radiotherapy after a modified radical mastectomy. Methods For the study, 20 patients with left-sided breast cancer who required adjuvant radiotherapy after a modified radical mastectomy were selected randomly. The specified dose of 43.5Gy/15f was adopted to plan for the IMRT and the VMAT. Dose volume histograms (DVH) were employed to evaluate the dose distribution of planning target volumes and organs at risk in both plans. Results The homogeneous index (HI) and conformity index (CI) of the VMAT group were found to be better than those of the IMRT group ( P < 0.05). VMAT showed better and more uniform dose distribution in the planning target volumes as well as a lower monitor unit (MU).No significant difference was found in V 5 of the affected lung and heart between the two groups ( P > 0.05). V 10 , V 20 , V 30 , and D mean of the affected lung and whole heart V 10 , V 20 , V 30 , V 40 , D mean , and D max of the VMAT group were better than those of the IMRT group ( P < 0.05). D mean and D max of the left anterior descending (LAD) of the heart in the VMAT group were better than those in the IMRT group ( P < 0.05), and the VMAT program was effective in reducing cardiopulmonary dose. A significant advantage of V 30 and D mean was found in the VMAT group over the IMRT group ( P < 0.05). Conclusions Compared with the IMRT program, the VMAT program achieved a higher clinical value since it improved the dose distribution in the target area, reduced the cardiopulmonary dose, protected organs at risk (OAR) (e.g., the thyroid), and shortened the treatment time.