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Implementation of the TG-147 Protocol in Conjunction with the Calypso GPS Tracking System for Higher Confidence of Prostate Patients Being Treated On RTOG Study 0938

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A Morris

A Morris1*, B Hasson2, P Sullivan3, C Hand4, S Philbrook5, (1) Bucknell University, Lewisburg, PA, (2) Anne Arundel Medical Center, Annapolis, MD, (3) Abington Memorial Hospital, Abington, PA, (4) Albert Einstein Medical Center, Philadelphia, PA, (5) ,Jenkintown, PA

SU-E-T-425 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose:
There are multiple factors that have lead to the need for an increased precision and accuracy in
Radiation Therapy. The increased use of IMRT and SBRT with hypofractionated doses requires optimal precision and accuracy in aligning the treatment delivery with the target. Recent advances in imaging and motion management of patients during the treatment process have provided a higher level of confidence for these types of treatments. The GPS based Calypso system is a non-radiographic localization and tracking systems. In order to ensure these systems are localizing and tracking with the high accuracy needed, a set of robust quality assurance procedures are required. Task Group Report (TG-147) of the AAPM describes QA for non-radiographic localization systems. The purpose of this work was to implement TG-147 with the Calypso 4D.

Methods:
The Calypso 4D system is composed of a console and a tracking station. The Calypso 4D is delivered with several quality assurance tools for initial and ongoing QA tests of the system. There are 3 distinct QA tools, which were adapted to the TG-147 protocol tests for the purpose of this study. TG-147 was analyzed for the application of QA procedures to Calypso. Calypso was then used to track prostate movement during standard IMRT and SBRT treatments.

Results:
Based on the review of TG-147 recommendations for daily, monthly, and annual tests new departmental QA procedures were implemented. The addition of an end-end localization plan, static and dynamic localization tests, and stability tests were incorporated into the existing QA program. Using Calypso, prostate movement during treatment was analyzed. Movement ranged from 0-3mm in the posterior and inferior directions.

Conclusion
The TG-147 recommendations provided a robust set of QA procedures that confirmed the Calypsos accuracy within 1mm. The new QA procedures have increased the confidence for tracking prostate movement during treatments.

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