ESTRO 2022 - Abstract Book

S391

Abstract book

ESTRO 2022

L. Allex 1 , M. Baumgartl 1 , K. Uher 1 , L. Motisi 1 , C. Linsenmeier 1 , M. Keane 1 , N. Kremer 1 , P. Petric 2

1 University Hospital Zürich, Department of Radiation-Oncology, Zürich, Switzerland; 2 University Hospital Zürich, Department of Radiation-Oncology , Zürich, Switzerland Purpose or Objective Image guided adaptive BT (IGABT) in the context of chemo-radiation (ChRT) improves outcomes when compared with conventional BT of cervical cancer. IGABT implementation requires technological upgrading, process adaptation and personnel training. Systematic clinical oversight is needed for its safe and effective utilisation, but recommendations on this topic are lacking. We aimed to develop and test a clinical quality assurance (cQA) system for cervix cancer ChRT/IGABT. Materials and Methods We identified treatment parameters with established prognostic impact on the outcome of cervical cancer ChRT/IGABT. For each parameter, an evidence-based threshold was determined, indicating the minimal proportion of patients in whom a certain condition should be met for optimal outcome. Based on this framework and the GEC ESTRO-ICRU 89 Report, we developed a system for routine recording and automated reporting of parameters. The system was tested on the first 4 consecutive cervical cancer patients treated with ChRT/IGABT at our department. Results We established 17 key performance indicators (KPIs) and a minimal required set of 6 dose-volume checkpoints for patient- specific cQA. KPIs were selected to probe 4 domains of treatment performance: overall ChRT schedule, IGABT procedure, doses to organs at risk and doses to target volumes. Patient-specific checkpoints were designed to track the total reference air kerma (TRAK) and relation between the D90 for high-risk clinical target volume and D2cc for rectum, bladder, sigmoid colon, bowel, and vagina. The automated reporting system was proven feasible for routine clinical use: cQA for the first 4 patients is presented in Figure 1.

Figure 1. (A) 17 KPIs. Red lines: literature benchmarks. (B) Patient-specific cQA. Red solid and dotted line: soft and hard constraint for high-risk clinical target volume (CTV-HR), respectively. Horizontal lines: dose constraints for respective organs at risk (OAR). Crossed squares: conventional BT; Circles: optimized IGABT. Each new patient is benchmarked against the population treated at the department up to that time. Cases with post-optimization location outside right lower quadrant warrant justification of deviation or re-optimization. (C) TRAK (presented as curie-seconds) as a function of CTV HR size. TRAK of each new patient is benchmarked to the experience of department up to that time. Conclusion Our cQA system enables standardized, automated and evidence-based oversight of ChRT/IGABT, real-time treatment adaptations, literature-benchmarking and continuous streamlining of clinical pathways. The system has been proven feasible and was implemented in routine clinical practice at our department.

OC-0448 Scintillator-based in vivo dosimetry during pulsed dose rate brachytherapy for cervical cancer