Room: AAPM ePoster Library
Purpose: To provide a complete framework for automatic treatment planning of spine SRS/SBRT that can generate multiple plans with different fractionations and take into account any organs at risk (OARs) present in the treatment area.
Methods: A fully automated script was implemented for spine SRS/SBRT plan generation using Eclipse v15.6 API. The script interface allows multiple dose/fractionation plan requests, PTV expansions, as well as information regarding distance/overlap between spinal cord and targets to drive decision making. For each requested plan the script creates the course, plans, field arrangements, and automatically optimizes and calculates dose. The script outputs the calculated plans, corresponding dose verification plans, and a dose objectives summary document. The script was retrospectively applied to six CT scans of previous thoracic spine SBRT patients. Three plans were generated for each patient: SIB 1800/1600cGy to GTV/PTV in one fraction; SIB 2700/2100cGy to GTV/PTV in three fractions; and 3000cGy to PTV in five fractions. Plan complexity and deliverability patient-specific QA was performed using ArcCheck with an Exradin A16 chamber inserted.
Results: For all plans, OARs dose objectives were met. Median target coverage was GTV V100%=87.3%, CTV V100%=95.7% and PTV V100%=87.1% for one fraction plans; GTV V100%=97.3%, CTV V100%=99.4% and PTV V100%=97.2% for three fraction plans; and PTV V100%=97.1% for five fraction plans. All plans passed patient-specific QA (>90%) at 2%/2mm global gamma. A16 chamber dose measured at isocenter (GTV centroid) agreed with planned dose within 1.5%. Beam-on time for all treatments was below 6 minutes. Total MUs/cGy averaged 2.81 for single fraction, 3.35 for three fraction, and 3.77 for five fraction plans.
Conclusion: Automation can increase the speed and efficiency of multiple plan generation for spine SRS treatment, increase plan robustness, standardize plan quality, and provide a tool for target coverage comparison of different fractionations without the need for additional resources.
Funding Support, Disclosures, and Conflict of Interest: Honorarium from Varian Medical Systems in the past (2019). This honorarium was not related to the subject matter of this research.