SU-E-T-515: Comparison of Two Dose-Specification Methods for the Treatment of Uterine Cervix Cancer with HDR Brachytherapy Using a Tandem and Ring Applicator

Medical Physics
N Bhandare, A Yeung

Abstract

To compare the dose to the high-risk clinical target volume (HRCTV)-D90 and dose-limiting structures with the dose prescription to point A (Manchester system) using conventional methods to image-guided treatment planning with dose optimization and a dose prescription to D90 of the HRCTV. CT-MR-fused image sets for 16 patients (stage IA2-IIIB) with uterine cervix cancer were obtained for each of 5 fractions of HDR brachytherapy using tandem and ring applicators to generate 2 sets of plans. In the first set, the dose was prescribed to point A with a standard dwell weight pattern reflecting the Manchester system loading pattern. In the second set, the dose was prescribed to D90 of the HRCTV with graphical plan optimization. Parameters of clinical significance (HRCTV-D90 and dose received by 1.0, 2.0, and 5.0cc of the bladder, rectum, and sigmoid) were compared, as recommended by GEC-ESTRO. HRCTV-V for 6 patients was =30cc (largest radius, <2.0cm) and >30cc (largest radius, =2cm) for the others. For the first set of plans, when HRCTV-V was <30cc, the ratio of doses HRCTV-D90/dose to point A varied from 1.10 to 1.40. When HRCTV-V was >30cc, it varied from 0.75 to 0.95. In the second set of plans, HRCTV-D90 always received the prescr...Continue Reading

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