BACKGROUND AND PURPOSE: To determine the extent of inter-observer variation in delineation of the heart and left anterior descending coronary artery (LADCA) and its impact on estimated doses. METHODS AND MATERIALS: Nine observers from five centres delineated the heart and LADCA on fifteen patients receiving left breast radiotherapy. The delineations were carried out twice, first without guidelines and then with a set of common guidelines. RESULTS: For the heart, most spatial variation in delineation was near the base of the heart whereas for the LADCA most variation was in its length at the apex of the heart. Common guidelines reduced the spatial variation for the heart and the length of the LAD, but increased the variation in the anterior-posterior/right-left plane. The coefficients of variation (CV) in the estimated doses to the heart were: mean dose 7.5% without and 3.6% with guidelines, maximum dose 8.7% without and 4.0% with guidelines. The CVs in the estimated doses to the LADCA were: mean dose 27% without and 29% with guidelines, maximum dose 39% without and 31% with guidelines. CONCLUSIONS: For the heart, there was little inter-observer variation in the estimated dose, especially when guidelines were used. In contrast, for the LADCA there was substantial variation in the estimated dose, which was not reduced with guidelines.
Radiotherapy and Oncology, 2013, Vol 108, Issue 2, p. 254-8
Breast cancer radiotherapy; Delineation; Heart dose; Inter-observer variation; Left anterior descending coronary artery; Aged Aged, 80 and over Breast Neoplasms/pathology/*radiotherapy/surgery Coronary Vessels/*radiation effects Denmark Dose-Response Relationship, Radiation Female Great Britain Heart/*radiation effects Humans Imaging, Three-Dimensional/methods Mastectomy, Segmental/methods Middle Aged Observer Variation Organs at Risk/*radiation effects Patient Safety Practice Guidelines as Topic Radiation Injuries/prevention & control Radiometry/methods Radiotherapy Dosage Radiotherapy Planning, Computer-Assisted/adverse effects/*methods Radiotherapy, Adjuvant Radiotherapy, Image-Guided/adverse effects/*methods Risk Assessment Sampling Studies Treatment Outcome; Comparative Study; Journal Article; Multicenter Study