A review of clinical trial radiotherapy quality assurance: value, evolution and lessons

Background and purpose: Deviations in radiotherapy quality can significantly affect clinical trial outcomes, including overall survival. Radiotherapy quality assurance (RTQA) is a systematic process by which a RT plan is analyzed with respect to the trial protocol. Therefore, RTQA is an essential step in clinical trials involving radiotherapy to ensure the reliability of the results. The objective of this review was to assess RTQA trends over time and parameters influencing the type of RTQA. Materials and methods: This is an overview of trials published in PubMed between 1988 and 2022 which performed and published their RTQA results. A search was also performed on the ClinicalTrials.gov database to find the actual number of clinical trials involving radiotherapy as treatment. Results: Between 1988 and 2022, 130 studies were identified to include RTQA in their methods. Of these studies, 96 trials published qualitative or quantitative analyses. During the same period, compared to registered trials on the Clinicaltrials.gov database, 1.15% and 0.84% of trials performed and published RTQA respectively. Seventy-three trials (58%) performed a benchmark case (BC) or dummy run (DR), 93 (73.8%) an individual case review and 24 (18,9%) an end-to-end audit. A higher proportion of prospective RTQA was found over time (BC/DR: 33.3% during 1988–1999 vs 100% during 2016–2022; ICR: 16.7% in 1988–1999 vs 50% in 2016–2022). Conclusion: In spite of RTQA being critical to ensure RT quality, a small number of trials perform it, and even fewer publish RTQA results. No significant increase in the conduction of RTQA over time was found, despite ongoing progress and increasing complexity in RT techniques. However, of the trials performing RTQA, this become more comprehensive over time. As RTQA continues to evolve in scope, including both contouring and plan review, consideration should be given to automation and tailoring to the specific trial, RT techniques and experience of the participating centers.Abbreviations: AI, artificial intelligence; BC/DR, benchmark case / dummy run; EORTC, European Organization for. Research and Treatment of Cancer; GHG, Global Clinical Trials RTQA Harmonization Group; GI, gastro-intestinal; HNSCC, head and neck squamous cell carcinoma; ICR, individual case review; IMRT, intensity modulated radiation therapy; OAR, organ at risk; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-analyses; RT, radiotherapy; RTQA, radiotherapy quality assurance; SBRT, stereotactic body radiotherapy; TROG, Trans-Tasman Radiation Oncology Group.