A Dosimetric Analysis of Reduction Cardiac Dose with Lead Shielding in Breast Cancer Radiotherapy

Hsiao-Wen Chiu,Chien-Yi Ting,Lu-Han Lai

doi:10.3390/app11209686

Hsiao-Wen Chiu, Chien-Yi Ting + Show 1 more

Open Access

https://doi.org/10.3390/app11209686

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Journal: Applied Sciences	Publication Date: Oct 17, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: Kuo General Hospital, Yuanpei University

Abstract

Adjuvant radiotherapy is an important treatment modality after breast-conserving surgery. Due to its proximity, radiation therapy for the left breast can often lead to an escalated heart dose that can result in heart diseases. The purpose of this study was to evaluate the heart dose reduction by using lead shields surrounding the left breast. The doses of a 3D conformal radiotherapy (3D-CRT) plan, an intensity-modulated radiotherapy (IMRT) plan, and volumetric-modulated arc therapy (VMAT) to the left breast tumor in a CIRS ATOM anthropomorphic female adult phantom were measured by optically stimulated luminescence dosimeters (OSLDs). To protect critical organs, the skin around the target area was covered by lead shields of two different thicknesses (0.125 mm and 0.25 mm). The results showed that compared to IMRT and 3D-CRT, VMAT provided better planning target volume (PTV) coverage, a better conformity index (CI), and homogeneity index (HI). With the use of lead shields, the thyroid dose was reduced by 5.12–27.5% and 20.51–30%, respectively; the heart dose was reduced by 49.41–50.12% and 56.38–57.42%, respectively; and the lung dose was reduced by 1.23–45.22% and 0.98–57.83%, respectively. Although the clinical application of lead shields was rare, this study verified that it could effectively decrease the heart dose from 4.31 ± 0.09 Gy to 1.88–2.18 Gy, thereby potentially reducing the risk of associated heart diseases by 14.8%. Further works to implement this method into clinical practice are needed.

Highlights

In radiotherapy for breast cancer, tangential fields that avoid irradiation to normal organs such as the heart and the lungs are traditionally adopted to reduce doses to these critical organs [1]
Multiple studies have indicated that intensity-modulated radiotherapy (IMRT) can produce a uniform dose distribution within the target volume as well as provide decreasing doses to the surrounding critical organs, thereby reducing complications, greatly enhancing prognosis, and improving the local tumor control rate [2,3,4,5,6]
The volumetric-modulated arc therapy (VMAT) plan had the best homogeneity index (HI) of 0.10 ± 0.01, followed by the IMRT plan with an HI of 0.13 ± 0.01 and the 3D conformal radiotherapy (3D-CRT) plan with an HI of 0.18 ± 0.02

Summary

Introduction

In radiotherapy for breast cancer, tangential fields that avoid irradiation to normal organs such as the heart and the lungs are traditionally adopted to reduce doses to these critical organs [1]. Multiple studies have indicated that intensity-modulated radiotherapy (IMRT) can produce a uniform dose distribution within the target volume as well as provide decreasing doses to the surrounding critical organs, thereby reducing complications, greatly enhancing prognosis, and improving the local tumor control rate [2,3,4,5,6]. Owing to the superior beam direction, the concept of tangential beams is still being used in some 3D conformal radiotherapy (3D-CRT) and IMRT treatments after modification [7,8,9,10]

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