MO‐F‐CAMPUS‐J‐03: Evaluation and Use of Cubic Phantoms for Daily IGRT QA Process with TrueBeam 6DoF Couch

Abstract

Purpose:To improve efficiency and efficacy of Daily IGRT QA process and to prepare for Varian TrueBeam 6DoF couch implementationMethods:MIMI phantom from Standard Imaging was compared to PentaGuide phantom from Modus Medical in order to replace and update our daily IGRT QA process. The following metrics were used as our evaluation criteria: contrast structures, predefined shift mark, TG‐142 compliance, support for 6DoF and ease of use. To improve process compliance, daily IGRT QA set up and process, an acrylic in‐house baseplates with known offsets were designed. New Daily IGRT QA protocol for 3DoF and 6DoF systems was developed and implemented into our practice. The selected phantom was used for the commissioning of Varian TrueBeam 6DoF couches and test the reproducibility and accuracy of 2D/2D and 3D/3D matching and localization processes. Baseline and tolerances for Daily IGRT QA for 6DoF couch were determined.Results:Based on our evaluation criteria, the MIMI phantom fit best our QA processes and matching goals. Comprehensive daily IGRT QA which includes CBCT 3D automatic registration, couch positioning, coincidence of kV/MV isocenters, image quality, and laser alignment were accurately and efficiently validated using the MIMI phantom and the setup baseplate with Varian TrueBeam and EX systems with 3DoF and 6DoF couches. Also, the use of MIMI phantom and setup baseplate was found to be a useful and effective tool for the commissioning of the Varian TrueBeam 6DoF couches.Conclusion:Implementation of MIMI phantom improved our Daily IGRT QA process by eliminating the use multiple phantoms which resulted in 40% Daily IGRT QA time reduction. Feedback from therapists has been positive and 100% compliance to new protocol has been achieved with minimal training. MIMI phantom was used to test the stability of the couch and to set baseline for Daily QA target and tolerance values.