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Overview of Routine Quality Assurance (QA) Processes at a Proton Therapy Center

E Leuro1*, Z Nevitt1 , D Maes1 , R Regmi1 , S Bowen2 , A Egan1 , P Taddei2 , C Bloch2 , T Wong1 , J Saini1 , (1) SCCA Proton Therapy Center, Seattle, WA, (2) University of Washington, School of Medicine, Seattle, WA


(Sunday, 7/29/2018) 3:00 PM - 6:00 PM

Room: Exhibit Hall

Purpose: Although proton therapy is a well-established treatment modality, limited resources exist to provide guidance on QA processes. Currently, there are no AAPM reports or peer-reviewed publications with recommendations regarding the type of QA procedures to be performed, their frequency, and magnitude of tolerances. We are presenting our experience at the proton therapy center (PTC) in implementing QA processes.

Methods: The PTC has variety of equipment for imaging, image guidance, therapy, and treatment planning system (TPS). Our center is equipped with a GE CT scanner, four IBA proton therapy rooms with uniform scanning and pencil beam scanning options, orthogonal kV x-ray image guide radiotherapy system , RayStation TPS, CMS Xio TPS, and Active Breathing Coordinator System. Our clinic also employs multiple detectors to perform routine QA on a daily, monthly and annual basis. While daily QA is performed by radiation therapists and reviewed by a qualified medical physicist (QMP), monthly and annual QA is undertaken by a QMP. The tolerances and frequencies for these QA tests are based on empirical experience and similar tests performed in photon clinics.

Results: Daily QA in a proton room includes mechanical, dosimetric and safety checks performed through 1-2 beam deliveries and can be performed in 20 minutes. Monthly QA consists of various tests for beam properties, patient positioning system, radiation/imaging isocenter co-incidence, CT number and image quality, dose calculation constancy, and review of daily QA records. Annual QA consists of additional checks to verify commissioning data in TPS, shielding evaluation, doses due to CT imaging, and output check through TRS-398 protocol.

Conclusion: A comprehensive QA program was instituted at proton therapy center. The QA processes underwent peer review during ACRO accreditation and were deemed to exceed minimum requirements. Our QA program experience can serve as a valuable guide for upcoming proton centers.


Not Applicable / None Entered.


IM- Particle (e.g., proton) CT: Quality control

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