ESTRO 2021 Abstract Book

S1439

ESTRO 2021

loop PRV. Conclusion

In this study, we observed up to 50% of protocol deviations in delineation of salvage radiotherapy treatments for nodal oligorecurrent PCa. While contouring of WPRT was more subject to variations, dosimetric variations were largest in the SBRT plans. Prospective RTQA programs should be implemented as critical component of future radiotherapy trials for oligometastatic disease. PO-1713 Risk analysis and quality assurance for a standalone single-room protontherapy facility A. Mazal 1 , J. Castro 1 , J.A. Vera 1 , J.M. Perez 1 , E. Pascual 1 , C. Ares 2 , R. Miralbell 2 , M. Cremades 3 1 Centro de protonterapia Quironsalud, Medical Physics, Madrid, Spain; 2 Centro de protonterapia Quironsalud, Radiation Oncology, Madrid, Spain; 3 Centro de protonterapia Quironsalud, Direction, Madrid, Spain Purpose or Objective To present the analysis done to identify and manage the main risks when setting a standalone single-room protontherapy facility, associated to a comprehensive quality assurance program. Materials and Methods The facility includes a single protontherapy room (IBA-ProteusOne), a double energy CT (Revolution-GE), treatment-planning (Raysearch), an Oncological-Information-System (Mosaiq-Elekta) and clinical staff of 20 FTE. The center is part of a large health system including close hospitals with radiation therapy departments. A risk analysis has been performed with specific local items related to protontherapy, standalone projects and environment. Results in this work correspond to safety and quality for proton treatments. Other chapters were evaluated elsewhere: the financial risk, the patient perception of quality and the risks of conventional radiation therapy. Results Seven groups and 11 subgroups of risks where listed, from technical to environment. We assigned 2 groups of tasks to eliminate or mitigate each risk. A grid from low (1) to severe (5) evaluate the severity (S), the probability (P) and the non-detectability (N). The S*P*N initial figure of merit had a maximum of 48 and a mean of 22. Table I shows a mitigation of the S*P*N factor to a maximum of 24 and a mean of 8,7 after performing 77% of tasks (31 for this table) assigned to small groups. Evaluations were performed systematically and before critical milestones (installation, acceptance-commissioning, starting clinical). A typical example of group of tasks were related to risk of breakdown and need to warranty the continuity of treatments. In a backup task, a 7-level root decision approach included night and Saturday shifts, a circuit of photon backups with pre-calculations and common immobilisations. The quality of the dose, clinical procedures, treatments and the full process was warrantied with external audits, protocols, intercomparisons (IROC-USA, NPL-UK, Centre Antoine Lacassage-Nice-France, ISOP, ISO9001,…), and for the individual cases through comparisons photons-protons, use of double energy CT for implants, weekly adaptive, and organ movements management (Vision RT and DynR spirometer). A systematic collection, analysis and action of precursors and undesirable events is performed.

Conclusion A specific risk analysis and a comprehensive quality assurance program based on standard methods and experience [1,2] may mitigate risks to an affordable level in complex projects like an innovative pioneer protontherapy project in a country, even if it is a standalone single-room project. A new evaluation is ongoing, reducing some risks and adding new factors, after a full year clinical ramp-up, with a hundred patients treated with highly complex situations (60% paediatrics) creating the “culture” of protontherapy as tool of choice for