Dosimetric Comparison of Treatment of Left Breast Cancer Using 3-Dimention Conformal Radiotherapy Technique and Tomotherapy

Abstract

Background: Breast cancer is the most common type of malignancy seen in women globally and the second life-threatening cancer among women after lung cancer. This research aims to compare the dosimetric differences based on two radiotherapy treatment plans for left breast cancer after surgery. Methods: CT scan data from 20 patients who were candidates for radiotherapy diagnosed with left breast cancer were randomly selected and sent to the treatment design software. The target organ (left breast) and organs at risk including lungs, heart, right breast were contoured by the radio-oncologist. The design of three-dimensional conformal radiotherapy (3D-CRT) was designed using two opposite tangential beams, depending on the patient's anatomy, with and without wedge and with energy of 6 MV. The tomotherapy treatment was designed with an energy of 6 MV. Finally, using the dose-volume distribution curve (DVH), the dosimetric variables of the target organ and the organs at risk were extracted and compared with each other. Findings: The three-dimensional conformal radiotherapy method reduced the average dose of the target organ and organs at risk compared to the tomotherapy method. The compliance index and homogeneity index were improved in the tomotherapy method, although the volume coverage of the left lung organ increased at low doses compared to the three-dimensional conformal radiotherapy method. Conclusion: The tomotherapy method is a more suitable method for treatment than the three-dimensional conformal radiotherapy method as it enhances the target volume coverage and offers a better dose distribution. © 2022 Isfahan University of Medical Sciences(IUMS). All rights reserved.