Cardiac dose in the treatment of synchronous bilateral breast cancer patients between three different radiotherapy techniques (VMAT, IMRT, and 3D CRT)

Abstract

Purpose Synchronous bilateral irradiation of both mammary glands and chest wall is a challenging task due to technical difficulties and limited evidence supporting an optimal technique to improve treatment outcomes. We studied and compared the dosimetry data of three radiotherapy techniques to select the most optimal one. Methods We compared three-dimensional conformal radiation treatment (3D CRT), intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) during irradiation of synchronous bilateral breast cancer in nine patients followed by examination of dose distribution to the cardiac conduction system (SA node, AV node and Bundle of His), myocardium, lungs, left anterior descending artery (LADA) and right coronary artery (RCA) . Results VMAT is the most sparing technique for SBBC treatment. Even though doses to the SA node, AV node and Bundle of His were higher with VMAT (Dmean were 3.75 ± 0.62, 2.58 ± 0.83 and 3.03 ± 1.18 Gy respectively) compared with 3D CRT (Dmean were 2.61 ± 0.66, 1.52 ± 0.38 and 1.88 ± 0.70 Gy respectively), this difference is statistically insignificant. Doses to the right and left lung (average Dmean = 12.65 ± 3.20 Gy, V20Gy = 24.12 ± 6.25%), myocardium (Dmean = 5.33 ± 1.51 Gy, V10Gy = 9.80 ± 3.83%, V20Gy = 7.19 ± 3.15%, V25Gy = 6.20 ± 2.93%), and LADA (Dmean = 10.04 ± 4.92 Gy, V20Gy = 18.17 ± 13.24% and V25Gy = 15.41 ± 12.19%) were highest with 3D CRT. The highest Dmean in the cardiac conduction system (5.30 ± 2.23, 3.15 ± 1.61 and 3.89 ± 1.85 Gy respectively) was observed with IMRT, and a similar effect was noted in RCA (Dmean = 7.48 ± 2.11 Gy). Conclusion VMAT is the optimal and satisfactory radiation therapy technique for sparing organs at risk (OARs). With VMAT, a lower Dmean value was noted in the myocardium, LADA, and lungs. The use of 3D CRT significantly increases the dose of radiation reaching the lungs, myocardium, and LADA, which can subsequently cause cardiovascular and lung complications, but not in the cardiac conduction system.

Dosimetric evaluation of different planning strategies for hypofractionated whole-breast irradiation technique

“…A review by Karaca presented a comprehensive dataset for hybrid whole-breast radiotherapy (WBRT), indicating that hybrid techniques can enhance dosimetric outcomes in WBRT (Karaca 2022). However, the adoption of hybrid techniques may elevate the number of monitor units (MUs) and treatment fields, enlarge the low-dose radiation exposure area in normal tissues, and result in a higher risk of secondary cancers (Grantzau et al 2013, Zhang et al 2020, Salim et al 2023. Another disadvantage of hybrid techniques is the requirement for multiple dose verifications, which increases the workload and complexity.…”