Development and Validation of a Heart Atlas to Study Cardiac Exposure to Radiation Following Treatment for Breast Cancer

Abstract

Purpose Cardiac toxicity is an important sequela of breast radiotherapy. However, the relationship between dose to cardiac structures and subsequent toxicity has not been well defined, partially due to variation in substructure delineation, which can lead to inconsistent dose reporting and the failure to detect potential correlations. Here we have developed a heart atlas and evaluated its effect on contour accuracy and concordance. Methods and Materials A detailed cardiac CT atlas was developed jointly by cardiology, cardiac radiology, and radiation oncology. Seven radiation oncologists were recruited to delineate the whole heart (WH), left main (LM), left anterior descending interventricular branch (LAD), and right coronary arteries (RCA) on four cases before and after studying the atlas. Contour accuracy was assessed by percent overlap with gold standard (GS) atlas volumes. The concordance index (CI) was also calculated. Standard radiation fields were applied. Doses to observer-contoured cardiac (OC) structures were calculated, and compared with GS contour doses. Pre- and post- atlas values were analyzed using a paired t-test. Results The cardiac atlas significantly improved contour accuracy and concordance. Percent overlap and CI of OC and GS volumes improved for all structures, by up to 2.3-fold (p<0.002). After application of the atlas, reported WH, LM, LAD, and RCA mean doses were within 0.1, 0.9, 2.6, and 0.6 Gy of GS doses. Conclusions This validated University of Michigan cardiac atlas may serve as a useful tool in future studies assessing cardiac toxicity and in clinical trials which include dose volume constraints to the heart.

Monitoring deep inspiration breath hold for left‐sided localized breast cancer radiotherapy with an in‐house developed laser distance meter system

“…The heart atlas by Feng et al. was used as guideline in our study 27. There is a decreased volume of the heart during DIBH which is probably due to increased intrathoracic pressure, and this is consistent with other studies that have found a 5%–10% reduction 6, 41.…”

“…Radiation therapists delineated the lungs and external contour. The breast was delineated according to national guidelines at the time of inclusion (http://www.nbcg.no), and the heart and LAD according to other published guidelines 27. Planning target volume (PTV) was automatically generated, derived from CTV with 10/5/5 mm extension in the superior‐inferior/anterior‐posterior/left‐right directions (SI/AP/LR), but always 5 mm inside the external contour.…”

Late radiation toxicity in Hodgkin lymphoma patients: proton therapy's potential

“…Prior to replanning, these OARs were contoured for each patient in a consistent manner. Lung volume was identified using the Eclipse lung segmentation tool (v.8.9, Varian Medical Systems, Palo Alto, CA), heart volume was defined using the Feng heart atlas, and the breast volume was defined using the consensus definitions of the Radiation Therapy Oncology Group Breast Cancer Atlas 21 , 22 …”

Clinical experience using a video‐guided spirometry system for deep inhalation breath‐hold radiotherapy of left‐sided breast cancer

“…The heart and left anterior descending artery (LAD) were segmented, following the Radiation Therapy Oncology Group heart atlas (7) . Patients were treated with tangential fields, with or without a matching supraclavicular field.…”