Abstract # 2029 Comparison of Intensity Modulated and 3D-Conformal Treatment Plans for Breast Radiation Delivered in the Prone Position

Presenter: Foltz, Gretchen

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Eleven archived prone cases previously planned with 3-DCRT were evaluated. The planned target volume included the entire breast (PTV50). The boost dose was delivered to a contour (PTV60) expanded 1cm in all directions around the lumpectomy cavity. DVHs for each plan were analyzed at 90%, 95%, 100%, 105%, 110%, and 125% of a goal dose of 50 Gy for whole breast and a 10Gy boost to the lumpectomy cavity. The contralateral breast, both lungs and the heart were evaluated as critical structures and analyzed using DVH to determine dose distribution. Seven treatment plans were completed for each patient:1) 3D-CRT without boost 2) 3D-CRT with boost, 3) 2 beam IMRT without boost, 4) 2 beam IMRT with boost, 5) 6 beam IMRT without boost, 6) 6 beam IMRT with boost, 7) 6 beam IMRT with concomitant boost (CB). The CB plans were based on the linear-quadratic model of biological response and 25 fractions were planned to deliver the biological equivalent dose of a 3D-CRT plan of 30 fractions. All plans (3D-CRT and IMRT) were generated using a CMS XIO treatment planning software. In this planning system dose to targets and critical non-target structures are optimized by a sequential iterative inverse planning algorithm.

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