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Assessment and Prediction of Treatment Plan Quality Through Integrated Planning Script

M Cao

M Cao*, D Ruan, J DeMarco, C King, P Kupelian, J Wang, D Low, UCLA Department of Radiation Oncology, Los Angeles, CA

MO-A-137-5 Monday 8:00AM - 9:55AM Room: 137

Purpose: To identify plan quality prognostic features that can be used to improve treatment plan quality and intra- and inter-planner consistency using a self-evolving institutional treatment planning workflow that employs treatment-planning scripts.

Methods:Institution-specific plan quality analysis software was developed using scripting integrated with a commercial treatment planning system (TPS). During treatment plan review, the script automatically extracted a set of representative quantities derived from dose volume histograms (DVH). The quantities were compared against national published standards and institution-specific criteria generated from statistics of accumulated planning data to assist in plan evaluation or further optimization. After plan acceptance, the plan quality indices and patient specific parameters, such as DVH endpoints and geometric features, were extracted by the script and saved into an evolving treatment plan database to update the existing institution-specific planning statistics.

Results: A treatment-planning database was constructed using a group of prostate patients (n=48) and following the proposed workflow. Dosimetric indices and geometric features were exacted and analyzed. For example, the PTV and OAR overlap volumes consistently provided good prognostic power for plan quality prediction. Retrospective analysis of the prostate planning database showed a consistent PTV volume coverage (PTV-V100 of 94.9±1.09%). No significant difference in PTV volume coverage was found for different prescription levels or target size. A conformity index (V50/VPTV) of 3.51±0.26 was achieved for prostate-only treatment plans. Strong correlations (R>0.8) were observed between OAR dose volume indices (Rectum V70Gy, V65Gy and Bladder V70Gy, V65Gy) and the OAR and PTV overlapping volumes.

Conclusion: The feasibility of automatic treatment plan quality aggregation, analysis and consistency improvement using planning scripts integrated into the treatment planning system was demonstrated in this pilot study. It is being incorporated into the clinical routine in our institute to determine its full utility.

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