Dosimetric comparison of modern treatment planning techniques for left sided breast cancer cases after mastectomy

Breast cancer is the most common type of cancer among women. Both curative and palliative radiotherapy can be applied in breast cancer radiotherapy. Major advances are happening in radiotherapy for breast cancer treatment. These advances aim at ensuring that planning target volume receives maximal dose while surrounding healthy tissues receive minimal dose at the same time. The purpose of this study is to determine the most appropriate treatment technique by comparing the field in field (FIF) technique and volumetric modulated arc therapy (VMAT) technique applied to ten patients with left-sided breast cancer after mastectomy. In the study, dose calculations were made with the application of a 0.3 cm bolus to the chest wall of each patient for each fraction in both techniques. The doses received by planning target volume (PTV) and healthy tissues at risk were determined for each treatment plan by means of dose volume histograms (DVH). Total monitor unit (MU) values were calculated for both plans. The homogeneity index (HI) and conformation number (CN) were calculated for the quality assessment of each plan. A statistical study was conducted to investigate whether there is a statistical difference in terms of dose distribution. When the data were analyzed, as a result of this study, it was found that the VMAT technique is better for the homogeneous dose distribution in PTV than the FIF technique while the FIF technique is more advantageous for total MU. It was found that as a planning technique the VMAT has the most ideal HI and CN values. It was found that the healthy tissues at risk including heart, brachial plexus and integral dose Dmean, left lung V5, whole lung, right breast, thyroid and esophagus are better preserved in FIF technique. It was found that the dose received by left anterior descending (LAD) and brachial plexus and integral dose Dmax are less in the VMAT technique as the doses of V20 of heart and left lung and LAD Dmean in both techniques are close to each other.