Optimizing Cardiac Safety: Dosimetric Analysis of Advanced  Radiation Techniques in Left Breast Cancer Therapy

Naveen. T; Uday Krishna; Nisarga. V.M; Tanvir Pasha; Sridhar. P; Magesharajan Khannan; Rashmi Shivananjappa

doi:10.31557/apjec.1841.20250520

Authors

Naveen. T Radiation Oncologist, Kidwai Memorial Institute of Oncology, Bangalore, India.
Uday Krishna Radiation Oncologist, Kidwai Memorial Institute of Oncology, Bangalore, India.
Nisarga. V.M Radiation Oncologist, Kidwai Memorial Institute of Oncology, Bangalore, India.
Tanvir Pasha Radiation Oncologist, Kidwai Memorial Institute of Oncology, Bangalore, India.
Sridhar. P Radiation Oncologist, Kidwai Memorial Institute of Oncology, Bangalore, India.
Magesharajan Khannan Radiation Physicist, Kidwai Memorial Institute of Oncology, Bangalore, India.
Rashmi Shivananjappa Radiation Oncologist, Kidwai Memorial Institute of Oncology, Bangalore, India.

DOI:

https://doi.org/10.31557/apjec.1841.20250520

Keywords:

Left breast, radiotherapy, VMAT, IMRT, 3DCRT, LAD dose.

Abstract

Purpose: This study aims to assess the incidental dose distribution to critical structures such as the heart, left anterior descending artery (LAD), and lungs using various external beam radiation techniques specifically, 3DCRT, IMRT, and VMAT plans.

Methods: Following approval from the Institutional Scientific Review Board (ISRB) and ethics committee, a meticulous statistical analysis was conducted based on a prospective enrolment of 60 patients. Written consent was obtained from all participants. The process involved CT simulation and precise contouring, generating three radiation plans for each individual.

Results: The study showed PTV 95 coverage was better achieved in VMAT (PTV95=99%). When coverage of VMAT was compared with 3D-CRT, P Value was statistically significant (P=0.007). The mean Dose to LAD was 15.29Gy with VMAT. The p-value obtained by comparing VMAT vs 3D-CRT was statistically significant (P=0.001). The volume of left Lung receiving 5%,10%, and 20% of the dose is better achieved with 3D-CRT.

Interpretation and Conclusion: This comparative dosimetric analysis of 3DCRT, IMRT, and VMAT in adjuvant radiotherapy for carcinoma of the left breast highlights the distinct advantages of VMAT in terms of superior PTV coverage and dose conformity. Notably, VMAT achieved a significantly lower mean dose to the LAD compared to 3DCRT, which is clinically relevant given the established correlation between radiation dose to the LAD and long-term cardiac morbidity. The reduction in LAD dose with VMAT strongly co-relates to a lower risk of radiation-induced ischemic heart disease and other late cardiac complications, reinforcing its role as an optimized treatment approach. While careful consideration of low-dose exposure to surrounding lung tissue remains essential, the overall benefits of VMAT in enhancing target coverage while minimizing cardiac risks make it a highly favorable technique in modern breast radiotherapy especially in left sided breast cancer treatment with preexisting heart diseases.