A Practical Solution to the Recommendations of TG-142 for a Respiratory Gating Program
E Cirino1*, I Iftimia1,2, P Halvorsen1, (1) Lahey Hospital & Medical Center, Burlington, MA, (2) Tufts University School of Medicine, Boston, MASU-E-T-152 Sunday 3:00PM - 6:00PM Room: Exhibit Hall
Purpose: To develop a practical solution to the recommendations of TG-142 for a Respiratory Gating Program
Methods: A phantom including an insert with a solid tumor and drilled for a chamber was placed on a motion platform. A 4DCT was performed. Two groups of images were generated. Group 1 was used to simulate the process of ITV generation and static treatment. Group 2 was used to simulate the gated treatment process. A measurement of the tumor motion noted on the CT data set was compared to the known motion in both cases. Base line output and ratio measurements were performed using a solid water phantom and 2 chambers placed at different depths in the phantom in both stationary and gated delivery. The Group 1 and Group 2 plans were then delivered using the moving platform with the intended treatment delivery technique. As an additional check IMRT QA was performed on the Group 2 plan.
Results: Tumor motion was confirmed. Baseline output measurements for stationary versus gated delivery were 101.1 cGy and 101.4 cGy respectively. The ratio of measurements at two depths was the same for both gated and static delivery. Central axis measurement of the Group 1 plan was 2123 cGy compared to the planned 2127 cGy. Central axis measurement of the Group 2 (gated) plan was 2142 cGy compared to the planned 2094 cGy. IMRT QA of the gated delivery showed 99% agreement for 3mm DTA and 3% absolute dose.
Conclusion: A baseline test with stationary and gated delivery coupled with an additional phantom end to end test as described can serve as a practical solution to the recommendations of TG-142 for a Respiratory Gating Program. It is anticipated that the complete testing from simulation to treatment can be completed in approximately 4 hours with experience.