Search

Purpose: To evaluate cone-beam computed tomography (CBCT) based setup accuracy and margins for prone and supine whole breast irradiation (WBI)., Methods: Setup accuracy was evaluated on 3559 CBCT scans of 242 patients treated with WBI and uncertainty margins were calculated using the van Herk formula. Uni- and multivariate analysis on individual margins was performed for age, body mass index (BMI) and cup size., Results: The population-based margin in vertical (VE), lateral (LA) and longitudinal (LO) directions was 10.4/9.4/9.4 mm for the 103 supine and 10.5/22.4/13.7 mm for the 139 prone treated patients, being significantly (p < 0.01) different for the LA and LO directions. Multivariate analysis identified a significant (p < 0.05) correlation between BMI and the LO margin in supine position and the VE/LA margin in prone position., Conclusion: In this series, setup accuracy is significantly worse in prone compared to supine position for the LA and LO directions. However, without proper image-guidance, uncertainty margins of about 1 cm are also necessary for supine WBI. For patients with a higher BMI, larger margins are required.

Purpose: To quantify the influence on heart dose metrics of prone left-sided whole-breast irradiation in an end-inspiratory phase (PrIN) versus an end-expiratory phase (PrEX)., Patients and Methods: Twenty patients underwent CT-simulation in PrIN and PrEX. Dynamic intensity-modulated radiotherapy was planned for whole-breast irradiation with a median prescription dose of 40.05Gy in 15 fractions and maximal sparing of the organs at risk. Dose-volume parameters were analyzed for heart, left anterior descending coronary artery, ipsilateral lung and both breasts., Results: PrIN consistently reduced (P<0.001) heart and left anterior descending coronary artery dose metrics compared to PrEX. Population averages for maximum and mean heart dose were 6.2Gy and 1.3Gy for PrIN versus 21.4Gy and 2.5Gy for PrEX, respectively. Moreover, a maximum heart dose less than 10Gy was achieved in 80% of patients for PrIN. Target dose distribution, ipsilateral lung and contralateral breast sparing by radiation dose were similar for both procedures., Conclusions: Inspiratory gating consistently reduced heart dose metrics pointing to a possible benefit of breathing-adapted radiotherapy for prone left-sided whole-breast irradiation., (Copyright © 2014 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.)

Background and Purpose: Cone-beam computerized tomography (CBCT) enables three-dimensional information of the scanned region and provides soft tissue images with good spatial resolution. Our aim was to optimize image acquisition settings for prone and supine breast radiotherapy with respect to contour accuracy, clinical practicalities, and radiation dose., Patients and Methods: CBCT images were acquired for both prone and supine anthropomorphic phantoms and a female cadaver in supine and prone set-up. CBCT protocols were investigated by altering the tube current, exposure time, range of projection views, field of view (FOV), and starting angle. For clinical practicalities, the frequency of the use of an offset CBCT isocenter was evaluated at 558 205°-CBCTs (37 patients; 13 prone and 24 supine) and 1272 360°-CBCTs (102 patients; 13 prone and 89 supine)., Results: Prone and supine breast CBCT images acquired with a bowtie filter, a small FOV, a range of projection views equaling 180°, a tube current of 20 mA and an exposure time of 32 ms, demonstrated adequate contour accuracy and an elimination of the offset CBCT isocenter procedure, while this occurred in 40.7 % for the old full-rotation protocol. Furthermore a 4.3-fold dose reduction was observed for the Computed Tomography Dose Index (CTDIw) compared to the preset Chest M20 protocol., Conclusion: The established 180° protocol demonstrated acceptable contour accuracy, eliminated the CBCT isocenter offset procedure and reduced patient radiation exposure.

Background and Purpose: Comparison of acute toxicity of whole-breast irradiation (WBI) in prone and supine positions., Materials and Methods: This non-blinded, randomized, prospective, mono-centric trial was undertaken between December 29, 2010, and December 12, 2012. One hundred patients with large breasts were randomized between supine multi beam (MB) and prone tangential field (TF) intensity modulated radiotherapy (IMRT). Dose-volume parameters were assessed for the breast, heart, left anterior descending coronary artery (LAD), ipsilateral lung and contralateral breast. The primary endpoint was acute moist skin desquamation. Secondary endpoints were dermatitis, edema, pruritus and pain., Results: Prone treatment resulted in: improved dose coverage (p<0.001); better homogeneity (p<0.001); less volumes of over-dosage (p=0.001); reduced acute skin desquamation (p<0.001); a 3-fold decrease of moist desquamation p=0.04 (chi-square), p=0.07 (Fisher's exact test)); lower incidence of dermatitis (p<0.001), edema (p=0.005), pruritus (p=0.06) and pain (p=0.06); 2- to 4-fold reduction of grades 2-3 toxicity; lower ipsilateral lung (p<0.001) and mean LAD (p=0.007) dose; lower, though statistically non-significant heart and maximum LAD., Conclusions: This study provides level I evidence for replacing the supine standard treatment by prone IMRT for whole-breast irradiation in patients with large breasts. A confirmatory trial in a multi-institutional setting is warranted., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)