Evaluation of Effect of Inverse and Field-in-Field IMRT Planning for Left-Sided Anterior Descending Coronary Artery Doses in Left-Sided Breast Cancer Patients

Abstract

OBJECTIVEThe aim of the study is to evaluate radiation doses of left-sided whole-breast irradiation on left-sidedanterior descending coronary artery (LAD) among various radiotherapy treatment planning techniquesfor 45 left-sided breast cancer patients.METHODSThree different radiotherapy techniques, field-in-field, 4-field inverse IMRT, and 5-field IMRT, wereundertaken. For inverse IMRT, the fields were special for each patient. We used 2 opposed tangentialbeams in the field-in-field technique, and for the other two techniques, the beams were obtained by 10°refraction.RESULTSThe 5-field IMRT technique is not useful for decreasing the LADmax dose. We figured out that in thefield-in-field technique, 18 of our 45 patients received doses greater than 10 Gy to LAD. We also foundthat using the 4-field inverse IMRT technique, LAD and lung doses could be reduced.CONCLUSIONThe mean LADmax dose was smaller than 10 Gy for all techniques except the field-in-field technique.There was no significant difference between 4-field inverse IMRT and field-in-field techniques. However,if LAD is located deeper than 2.5 cm, the LADmax dose could increase; this could further be decreasedto under 10 Gy using the 4-field inverse IMRT technique.