title: The dosimetric impact of respiratory breast movement and daily setup error on tangential whole breast irradiation using conventional wedge, field-in-field and irregular surface compensator techniques.
abstract: To evaluate the dosimetric impact of respiratory breast motion and daily setup error on whole breast irradiation (WBI) using three irradiation techniques; conventional wedge (CW), field-in-field (FIF) and irregular surface compensator (ISC). WBI was planned for 16 breast cancer patients. The dose indices for evaluated clinical target volume (CTV(evl)), lung, and body were evaluated. For the anterior-posterior (AP) respiratory motion and setup error of a single fraction, the isocenter was moved according to a sine function, and the dose indices were averaged over one period. Furthermore, the dose indices were weighted according to setup error frequencies that have a normal distribution to model systematic and random setup error for the entire treatment course. In all irradiation techniques, AP movement has a significant impact on dose distribution. CTV(evl)D(95) (the minimum relative dose that covers 95 % volume) and V(95) (the relative volume receiving 95 % of the prescribed dose) were observed to significantly decrease from the original ISC plan when simulated for the entire treatment course. In contrast, the D(95), V(95) and dose homogeneity index did not significantly differ from those of the original plans for FIF and CW. With regard to lung dose, the effect of motion was very similar among all three techniques. The dosimetric impact of AP respiratory breast motion and setup error was largest for the ISC technique, and the second greatest effect was observed with the FIF technique. However, these variations are relatively small.
authors.affiliation: Department of Radiology, Faculty of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan. tfuruya@juntendo.ac.jp
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Furuya
authors.forename: Satoru
authors.initials: S
authors.lastname: Sugimoto
authors.forename: Chie
authors.initials: C
authors.lastname: Kurokawa
authors.forename: Shuichi
authors.initials: S
authors.lastname: Ozawa
authors.forename: Kumiko
authors.initials: K
authors.lastname: Karasawa
authors.forename: Keisuke
authors.initials: K
authors.lastname: Sasai
mesh_terms: D016477:Artifacts; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D009068:Movement; D056888:Patient Positioning / Q000379:methods*; D011859:Radiography; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal; D061089:Radiotherapy, Image-Guided / Q000379:methods; D015203:Reproducibility of Results; D015656:Respiratory Mechanics; D012680:Sensitivity and Specificity; D016896:Treatment Outcome