A cardiac contouring atlas for radiotherapy

Publication date: Available online 21 February 2017
Source:Radiotherapy and Oncology
Author(s): Frances Duane, Marianne C. Aznar, Freddie Bartlett, David J. Cutter, Sarah C. Darby, Reshma Jagsi, Ebbe L. Lorenzen, Orla McArdle, Paul McGale, Saul Myerson, Kazem Rahimi, Sindu Vivekanandan, Samantha Warren, Carolyn W. Taylor
Background and purposeThe heart is a complex anatomical organ and contouring the cardiac substructures is challenging. This study presents a reproducible method for contouring left ventricular and coronary arterial segments on radiotherapy CT-planning scans.Material and methodsSegments were defined from cardiology models and agreed by two cardiologists. Reference atlas contours were delineated and written guidelines prepared. Six radiation oncologists tested the atlas. Spatial variation was assessed using the DICE similarity coefficient (DSC) and the directed Hausdorff average distance (d→H,avg). The effect of spatial variation on doses was assessed using six different breast cancer regimens.ResultsThe atlas enabled contouring of 15 cardiac segments. Inter-observer contour overlap (mean DSC) was 0.60–0.73 for five left ventricular segments and 0.10–0.53 for ten coronary arterial segments. Inter-observer contour separation (mean d→H,avg) was 1.5–2.2mm for left ventricular segments and 1.3–5.1mm for coronary artery segments. This spatial variation resulted in <1Gy dose variation for most regimens and segments, but 1.2–21.8Gy variation for segments close to a field edge.ConclusionsThis cardiac atlas enables reproducible contouring of segments of the left ventricle and main coronary arteries to facilitate future studies relating cardiac radiation doses to clinical outcomes.



http://ift.tt/2kVNm3H