Program Information
Accelerating Online Adaptive Replanning with Incomplete Normal-Structure Delineation
S N Lim*, E E Ahunbay , X A Li , Medical College of Wisconsin, Milwaukee, WI
Presentations
SU-K-601-1 (Sunday, July 30, 2017) 4:00 PM - 6:00 PM Room: 601
Purpose: Online adaptive replanning (OARP), which has been shown to effectively address interfractional variations, is time-consuming and labor intensive due primarily to the required delineation of the target and surrounding organs. In this work, we introduce a strategy to accelerate OARP by using incomplete normal structure contours to reduce the delineation effort.
Methods: A research treatment planning tool (Monaco, Elekta) was used for OARP. Planning and daily CTs for three prostate cancer cases and planning and daily MRIs for three pancreatic cancer cases were selected to demonstrate the idea. Full target and OAR contour sets from planning CTs/MRIs were populated to the daily CTs/MRIs based on deformable image registration (ADMIRE, Elekta). The populated contours on daily images were edited to obtain a full and a partial contour sets for each daily image. For the partial contour set, the full CTV/PTV and segments of OARs within 2 cm beyond PTV in axial planes and 2 slices superior/inferior to the PTV were delineated. On each daily image, two plans using identical optimization dose-volume constraints were generated with full and partial contour sets.
Results: Dose-volume parameters for the full- and partial-contour plans are comparable. For example, PTV Vāāā was almost identical and PTV maximum doses agreed within 54 cGy between the two plans. Differences on maximum and mean doses on OARS were within 6% and 8%, respectively. Larger differences were seen in the pancreas cases due to the larger number of OAR contours.
Conclusion: Replanning with partial OAR contours can lead to adaptive plans comparable to those generated with full OAR contours. Requiring only partial OAR contours reduces segmentation effort, speeding up online replanning especially for tumor sites with a large number of OARs.
Funding Support, Disclosures, and Conflict of Interest: This work is partially supported by Elekta AB.
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