The radiation doses to the heart and the left anterior descending coronary artery for various modes of radiation treatment of the breast cancer patients.

Abstract

e12092 Background: The comparison of the radiation load to the organs at risk for three modes of radiation treatment of the breast cancer patients. Methods: The research includes the dosimetric radiation treatment plans for the 20 breast cancer patients with the left-side localization. They all underwent a computed tomography (CT) scan in standard supine position in free-breathing (FB), supine position with Active Breathing Control (ABC) device in deep inspiratory breath hold, and prone position in free-breathing (PP). Three-dimensional treatment plans were made for all 3 CTs. The dose valuations for 3D-planning were carried out for three CT- series. For each mode of radiation, the doze-volume parameters of organs at risk were estimated. Results: For all cases the contoured heart volume varied from 477 см3 - 1056 см3, with medium volume 769 см3. The best marks such as V25heart, medium doses to the heart and LAD, were achieved with on ABC methods (V25heart 4,26%, Dmean heart 3,13Gy, DmeanLAD 13,8Gy) in comparison FB (V25heart 9,49%, Dmean heart 4,97Gy, DmeanLAD 19,55Gy) and PP (V25heart 12,8%, Dmean heart 9,06Gy, DmeanLAD 24,18 Gy) (V25heart P = 0.00153, Dmean heart: P =0,000; Dmean LAD: P = 0.00088), when both the breast and the axillary nodes were included in the volume. The advantage of the dosimetric indexes for FB and ABC did not change while axillary and supraclavicular nodes were added to the radiation volume ABC (V25heart 3,49%, Dmean heart 3,08Gy, DmeanLAD 13,88Gy) in comparison with FB methods (V25heart 7,91%, Dmean heart 4,99Gy, DmeanLAD 19,89Gy) (V25heart P = 0.00205, Dmean heart: P =0,004; Dmean LAD: P = 0.03). Conclusions: Radiation treatment in the position on the back with controlled delay of breath on inspiration height contributed to the statistically significant reduction of the heart volume exposed to more than 25 Gy (V25heart), mean dose to the heart and mean dose to LAD.