Original ArticleDose-sparing effect of deep inspiration breath hold technique on coronary artery and left ventricle segments in treatment of breast cancer☆
Section snippets
Patient selection
Institutional Review Board approval was obtained prior to study commencement. In this retrospective dosimetric analysis, patients with left-sided invasive breast cancer or ductal carcinoma in situ (DCIS) who have been treated with breast conserving surgery and adjuvant whole breast irradiation using DIBH technique were identified and included in the study. Since the introduction of the DIBH technique at our institution in 2017, all patients who were treated using the DIBH technique between
Image acquisition
Patients were simulated with computed tomography (CT) scans using both the DIBH and FB techniques on the same day. CT scans were acquired using 3 mm thick slices, as patients rested in the supine position on a breast board with both arms above the head and a cushion under the knees. Radio-opaque wires were placed to delineate the anatomical border of the entire left breast, with the medial boarder at mid-sternum and the lateral border at the mid-axillary line, and small permanent tattoos were
Contouring structures
The following structures were contoured on both DIBH and FB scans using Elekta Monaco® Treatment Planning Software (TPS) v.5.11.02 (Elekta, Stockholm, Sweden): right and left lung, breast, surgical scar, heart, right coronary artery (RCA), left main coronary artery (LMCA), left circumflex coronary artery (LCX), left anterior descending coronary artery (LAD) and left ventricle (LV). LAD was then further divided into proximal (pLAD), middle (mLAD) and distal (dLAD) segments, and LV was further
Treatment planning and dose calculation
The contoured structures on both DIBH and FB scans were then submitted for treatment planning using Elekta Monaco® TPS v.5.11.02 (Elekta, Stockholm, Sweden) (Fig. 1). Treatments were delivered using three-dimensional conformal radiotherapy (3D-CRT) with two parallel opposed pair tangent beams. These consisted of a combination of 6MV and 10MV photons. Sub-fields were used to improve target coverage and maximize dose homogeneity within the breast, while minimizing the dose to the organs at risk
Results
A total of 75 patients were identified and included in the study. Median age at the time of treatment was 59 years (range 37–78 years) and the majority (80%) of patients had invasive cancer, while the rest (20%) had DCIS. Fifty-six percent of patients received 42.5 Gy in 16 fractions and 44% of patients received 40 Gy in 15 fractions. Forty-seven percent of patients received a boost dose to the tumor bed ranging between 10 Gy and 12.5 Gy in 4–5 fractions.
Mean volumes of the whole heart, LAD and
Discussion
The results from our study demonstrate that DIBH effectively reduces doses to the heart and left lung in left-sided breast cancer patients treated with whole breast irradiation. The dose reductions from DIBH were pronounced in certain cardiac structures, especially the LAD and LV, while the reductions were less significant in other structures, including the whole heart and other coronary arteries, such as the RCA, LCX and LMCA. In addition, when individual segments of the LAD and LV were taken
Role of the funding source
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgement
None.
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2022, Physica MedicaCitation Excerpt :The deep inspiration breath-hold (DIBH) technique is the best solution to reduce the doses to the heart and cardiac segments. DIBH physically pulls the heart away from the chest wall, thereby effectively reducing the doses to these structures [2,3]. Despite the substantial benefits of DIBH, it is not commonly used in routine clinical practice due to several reasons [4]: implementation of the DIBH technique typically requires a gated simulation computed tomography (CT) scan and subsequent synchronization of the radiation delivery to the respiratory cycle; it requires radiation therapists and physicists with specific expertise, who may not be available at all hospitals; and it increases daily treatment time per patient by approximately 33% and may not be feasible in centers already operating at capacity.
Comparison of setup accuracy of optical surface image versus orthogonal x-ray images for VMAT of the left breast using deep-inspiration breath-hold
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Presented in part at the following: 2019 ASTRO Annual Meeting, September 2019, Chicago, IL, USA. Annual Scientific Meeting of the 2019 Canadian Association of Radiation Oncology (CARO), October 2019, Halifax, NS, Canada.