Purpose: The quality of radiation delivery has been shown to impact clinical outcomes significantly. External dosimetry audits are widely implemented as additional independent tools to ensure safe delivery of treatments, however have found problems despite facilities passing the audit plans with their own patient specific quality assurance (PSQA). This work presents a new concept for dosimetry audits which assesses the sensitivity of a facility’s clinical PSQA to detect relevant errors.
Methods: Treatment delivery errors which produce clinically significant changes to treatment plans, yet are within or close to the specifications of the treatment delivery system, were designed and introduced into Spine SBRT treatment plans from participating facilities. Each facility submitted one plan using a provided data set and planning guidelines. They received twelve versions of the plan back, on which they then performed their standard clinical PSQA. Identical errors were used for all facilities and the impact of the errors in the plans was assessed individually.
Results: Seventeen facilities from Australia, the UK and the US participated in the study, using six different radiation treatment planning systems and the two major radiation treatment delivery systems. Of the twelve versions of a participant’s plan, between two and eight passed the local PSQA. Six of the error plans (from four facilities) which had caused a >10% increase in radiation dose to an organ at risk still passed the PSQA. If the threshold was reduced to >5% this rose to 18 plans (seven facilities).
Conclusion: Going beyond the current approach to test a facility’s ability to deliver a selected test case, this novel audit methodology could improve the precision of institutional PSQA, thus improving quality in every facility, impacting many patients. The developed system is administered fully remotely, which provides advantages in cost, environmental impact and logistics.
Funding Support, Disclosures, and Conflict of Interest: This work has been supported by a Hunter Cancer Research Alliance (HCRA) Radiation Oncology, Cancer Imaging & Technology (ROCIT) Flagship Program grant (Newcastle, Australia).