ESTRO 2023 - Abstract Book

S399

Sunday 14 May 2023

ESTRO 2023

Contour instructions included creation of CTVA, B and C, requiring automated and manual expansions plus editing for normal structures (ENS). For lower-third cases, inclusion of an elective lymph node irradiation (ELNI) volume within CTVB, and for 4D cases, creation of an ITV using the full 4D dataset, was necessary. Construction of PTV5000 (standard) and 6000 (DE) using automated expansion was mandated. All centres were required to submit an IMRT/VMAT planning exercise using another pre-outlined 3D dataset. Submissions were evaluated by an RTTQA reviewer using pre-defined criteria, and thence deemed “acceptable” or “unacceptable: resubmission required”. Contemporaneous feedback reports were retrospectively reviewed, and the domain of unacceptable deviations (UDs) recorded. Results For SCOPE2, 84 contour datasets from 33 centres were submitted. 20 were resubmissions. In total, 49/84 (58%) submitted contours were accepted: 12/15 (80%) mid-third 3D, 21/35 (60%) lower-third 3D and 16/34 (47%) 4D. CTVB (39/83, 47%) deviations, which included ENS and ELNI contouring, were most common UDs. PTV6000 (10/83, 12%) and ITV (13/43, 30%) UDs were also frequent. 52 plans from 39 centres were submitted. 9 were resubmissions. 44/52 (85%) were VMAT. 44/52 plans were accepted; 8 (15%) had UDs related to PTV coverage/conformality (c/c). OAR dose constraints were met for all. pre-accrual. By comparison, PRODIGE-26 report a similar rate of acceptable submissions (32/43, 74%), with most common contouring deviations also observed in CTV. In contrast, no UDs in CTV were seen; this difference may in part be explained by SCOPE2 ENS and 4D components. UDs in PTV c/c were similar (4/43, 9%), but in OAR constraints more frequent (7/43, 16%); this is attributed to rates of 3D conformal planning (18/43, 42%). In conclusion, pre-accrual RTTQA findings for SCOPE2 and PRODIGE-26 are broadly comparable. The additional complexity of SCOPE2 contouring protocol and advances in planning techniques may explain differences in UD rates, but findings strongly confirm the ongoing need for rigorous RTTQA in oesophageal RT. Conclusion A high frequency of RTTQA protocol deviations were observed at SCOPE2 PD-0491 Failure Mode and Effects Analysis (FMEA) evaluation of the radiotherapy treatment delivery process. V. Pisoni 1,2 , R.M. Niespolo 1 , V. Tremolada 3 , S. Trivellato 3 , E. Ierman 1 , T. Brandolese 1 , M. Pusceddu 1 , P. Mazzoni 2 , S. Arcangeli 2,1 1 ASST Monza, Radiation Oncology, Monza, Italy; 2 University of Milan Bicocca, Medicine and Surgery, Milan, Italy; 3 ASST Monza, Medical Physics, Monza, Italy Purpose or Objective To ensure the correct delivery of increasingly complex radiotherapy (RT) treatments avoiding undue exposures to patients, it is essential to use proactive methods of risk management. This study describes the application of the Failure Mode and Effect Analysis (FMEA) in order to enhance the safety and quality of the RT treatment delivery process. Materials and Methods Following the FMEA multidisciplinary approach, a mono-institutional group of 4 RTTs, 1 RTT student, 1 radiation oncologist and 2 medical physicists was set up and met on a weekly basis from May to October 2022. FMEA was applied to the treatment delivery proceeding as follows: 1) identification of the single steps (phases and activities), based on previously performed process analysis and existing documents as part of ISO 9001 Quality System; 2) for each activity, identification of the potential failure modes (FM), together with their causes and effects; 3) for each FM, severity (S), occurrence (O) and detectability (D) were discussed and rated using the AAPM TG-100 radiotherapy specific scales; 4) Risk priority number (RPN) was calculated as the product of S, O, and D (range 1-1000). Additional safety measures, improvements, or mitigations were proposed and considered for FM with a RPN higher than 180. Results Six phases were identified with seventeen activities. A total of 56 FM was recognized with RPN ranging from 27 to 576, 23 of them (41%) characterized by an RPN score higher than 180. The highest RPN (576) was associated to wrong IGRT parameters definition. The solutions proposed to mitigate the O of this FM were the adoption of strict IGRT protocols and an accurate training of the involved users. Other critical RPNs were related to wrong or missing bolus application (450), incorrect assessment of patient’s clinical conditions before starting the treatment (400), wrong evaluation of EPID images (360) and undetected patient’s movements during treatment (320). Effective strategies identified for risk mitigation included: organizational changes, improved communication modes, and new technologies, such as Surface Guided Radiation Therapy systems and EPID in vivo dosimetry. Conclusion The FMEA method proved to be a reliable and effective approach of risk management for the RT treatment delivery process. The presented results were generated by consensus of a multidisciplinary group of professionals following RT specific ranking scales, guaranteeing a critical and shared scoring. A continuous review and update of activities, FM and ratings is mandatory to ensure safety and quality to a process in such rapid and constant evolution. The results could be a useful tool to suggest and support the introduction of novel technologies.

PD-0492 Does rectal volume on pre-radiotherapy scans predict prostate motion during treatment?