3327 - Analysis of the Treatment Planning Quality Assurance Reports for Intensity Modulated Proton Therapy at an Established Proton Center

M. Zhu¹, R. Slopsema², M. Pasha², and K. M. Langen¹; ¹Department of Radiation Oncology, Emory University, Atlanta, GA, ²Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, GA

Purpose/Objective(s): Proton therapy is a complex treatment modality; establishing a safe and effective clinical workflow is a challenge faced by many proton facilities. We aim to share our experience accumulated over the past few years at a multi-room proton center. Materials/Methods: At our clinic, qualified medical physicists check the patients’ plans three times throughout the treatment planning workflow: pre-planning check (before plan generation), plan review (right after plan generation), and the initial chart check before the treatment course starts. Since March 2021, a voluntary reporting process was implemented within the physics and dosimetry group, as a quality improvement initiative. Details of the reported issues were investigated, strategies of improvement were proposed and presented to the group bi-monthly.

Results: Over the past three years, a total of 170 issues were collected and analyzed. Ninety-seven (57%) were related to plan generation, 44 (26%) occurred during pre-planning stage, 11 (6%) during post-planning plan export and documentation, 7 (4%) from patient simulation, and 11 (6%) in other stages. The top 5 most common issues are listed in the table. Plan reviews and initial chart checks caught 74 and 58 issues, respectively; 10 issues were reported from the pre-planning stage, and 24 issues reached the patient treatment stage. Only 65 (38%) issues were caught by the first check; unfortunately, 42 (25%) issues were missed once (caught during second check), and 31 (18%) missed twice, and 32 (19%) missed three time or more. Most of these issues had no (110) or negligible (37) impact, 23 had some impact, but were all still acceptable. There were 118 unique issues found, while the other 52 were repeated occurrences. From these issues, 15 were now included in automatic checks utilizing scripting, and 3 prompted workflow and SOP improvement.

Conclusion: Our analysis showed there is room for improvement, even for an established proton center staffed with experienced physicists and dosimetrists. Our policy with multiple checks throughout the workflow is essential for patient safety and improves quality of proton radiotherapy. Our experience could provide guidance to new and future centers.

Abstract 3327 – Table 1

N. of occurrence	Detail of the issues
43	suboptimal optimization/poor plan quality
17	spot placement issues
14	density override for imaging artifact and implants (breast, spine hardware, surgical clips, fiducials)
9	suboptimal beam angle
7	suboptimal isocenter position