Dosimetric Evaluation of Three-Dimensional Conformal Radiation Therapy Breast Cancer Treatment Plans

Breast cancer is one of the most common cancers affecting women worldwide. Radiotherapy plays a pivotal role in breast cancer management. This study aims to conduct a comprehensive dosimetric analysis of breast cancer patients undergoing radiotherapy. In this study, 28 breast cancer patients were analyzed for various dosimetric parameters, including D98%, D95%, D50%, D5%, and D2%, as well as maximum, minimum, and mean doses within the PTV. PTV volume coverage was assessed at 95%, 93%, and 91% of the prescribed dose, with hot spot dose volumes at 115%, 110%, 108%, and 105%. Doses to organs at risk (OARs) were also evaluated. Dosimetric indices—uniformity index (UI), conformity index (CI), and homogeneity index (HI)—were calculated to assess treatment quality. Right-sided patients received higher doses at D98% and D95%, with smaller differences at D50%, D5%, and D2%. Left-sided patients had higher mean maximum and mean doses within the PTV, while right-sided patients had higher minimum doses. Left-sided chest wall-only patients showed higher hot spot volumes at 110% and 105%, though all patients had minimal volumes at 115%. Ipsilateral lung V20 was below 35% for all, with higher values in the chest wall and supraclavicular treatments. The mean heart dose was higher for left-sided treatments but stayed below cardiac toxicity limits. UI was slightly better in right-sided "Breast & SC" plans, and CI was higher in right-sided patients, while HI was higher in right-sided "Breast & SC" than left-sided "Breast Only." The study highlights differences in dose distribution between left and right-sided patients, with right-sided cases receiving higher doses at key points and left-sided cases showing larger PTV volumes and greater heart exposure. Dosimetric indices suggest treatment refinement may be needed, particularly for left-sided cases, to improve outcomes and reduce toxicity.