ESTRO 37 Abstract book

S116

ESTRO 37

selected for protons are included in a prospective observational cohort study, in which the performance of the photon-based NTCP-models are continuously tested on model performance using the closed testing procedure. The closed testing procedure is a method to assess whether NTCP-model adjustment is required and to what level, varying from no adjustment, recalibration- in-the-large, recalibration, model refit or model revision. This approach requires Rapid Learning Health Care systems. Conclusion The model-based approach is an alternative evidence- based methodology to select patients for protons therapy and to test if the new technology eventually results in lower rates of radiation-induced side effects SP-0219 EPTN WP2: Dosimetry and quality assurance S. Safai 1 , O. Jäkel 2 , S. Menkel 3 1 Paul Scherrer Institute PSI, Center for Proton Therapy, Villigen PSI, Switzerland 2 Deutsches Krebsforschungszentrum, Medical Physics in Radiation Oncology, Heidelberg, Germany 3 Universitätsklinikum Carl Gustav Carus, Proton Therapy Center, Dresden, Germany Abstract text WP2 is the second work package of the European Particle Therapy Network (EPTN) referred to as “WP2: dose assessment, quality assurance, dummy runs and technology inventory”. The focus of this work package is on dosimetry and quality assurance in particle therapy. As of today 14 centres of 8 different countries are represented in WP2. During the WP2 workshop held in March 2017 in Brussels six working groups within WP2 have been created to cover different aspects of dosimetry as listed below. This abstract contains extracts from the ESTRO newsletter No. 113 (July – August 2017) pertain to WP2. The 6 working groups (WG) 1) Quality assurance/equipment survey : a questionnaire has been prepared and distributed across the centres in Europe to collect information on the dosimetric quality assurance tests performed on particle machines, including the type of test, the frequency, the tolerance, the duration, the resources required, the level of satisfaction and the equipment used. The aim is to become aware of the spectrum of approaches used in the different centres, to learn from the experience of such centres and to encourage discussions targeted to harmonize the QA program in Europe. The survey will also help to better identify the dosimetry areas in which WP2 could contribute to. 2) Reference dosimetry : the current standards (code of practice) on reference dosimetry do not cover in a satisfactory way the particular needs of particle scanning machines with regard to reference dosimetry and primary monitor calibration. We are therefore glad that other committees outside of EPTN are currently addressing and updating the definition of such standards. The role for this working group is to gather the experience from different centres by sharing the results on this topic to provide valuable inputs to the existing committees. We are therefore closely following the update of the Technical Reports Series (TRS), where members of the WG are involved. The WG, among others, will propose well-defined tests for a better interpretation of the results across the institutes. 3) Audits : the aim is to create a network of centres interested in participating in reference dosimetry audits and end-to-end audits. Similar to “Reference dosimetry” this working group is defining standard tests to be performed with an anthropomorphic phantom, which can be shared between centres. 4) Patient specific verification : this WG aims at understanding how patient specific verification is

Gaining a basic understanding of Big Data and technologies based in it, including their strengths and weaknesses, is the overall aim of this teaching lecture. Specifically, the lecture addresses the following questions: - What is the rationale behind using Big Data for data driven medicine and what is the relation to evidence base medicine? - What is Big Data in (radiation) oncology? What types of data are there? How big is the data really? And where is it? - How do you deal with privacy protection? - What is the quality of Big Data? - How can you get access to Big Data? How does one learn from Big Data? - How do you critically appraise and apply Big Data results into daily practice? The teaching lecture is suitable for a wide audience, and targeted to practicing radiation oncologists, medical physicists and RTTs who wish to get an overview on the topic.

Symposium: European Particle Therapy Network (EPTN)

SP-0218 EPTN WP1: Clinical trial designs to assess the benefit of protons H. Langendijk 1 1 UMCG University Medical Center Groningen, Department of Radiation Oncology, Groningen, The Netherlands

Abstract text Background

Randomized controlled trials (RCT’s) are considered the gold standard of evidence-based medicine. This is certainly true if new radiation technologies like protons are introduced to improve efficacy in terms of local tumor control and/or overall survival. However, most new radiation technologies are clinically introduced to further reduce the unintended dose to the normal tissues primarily aiming at reduction of radiation-induced side effects. There is growing recognition that for such purpose, RCT’s are probably not the most ideal study design, given major variability in performance between centers, rapid technological developments and variability in the level of expected clinical benefit for individual patients. Therefore, alternative evidence-based methods are needed and available. Model-based approach The model-based approach is an alternative evidence- based methodology developed to select patients for proton therapy and to clinically validate the added value of new radiation-induced technologies aiming at reduction of radiation-induced side effects. Model-based selection Model-based selection consists of 3 steps. Step 1 includes the selection of high quality NTCP-models. Step 2 includes a planning comparative study for each individual patient comparing photon with proton plans to assess the difference in dose volume histogram (DVH) parameters derived from the NTCP-model (DDose). Step 3 includes the integration of the results of the individual planning comparative study into the NTCP-model selected to translate DDose to DNTCP. The level of DNTCP can then be used for selection of patients. Model-based validation The principle of model-based validation is to test the hypothesis that the observed rate of radiation-induced side effects obtained with the new technology (i.e. protons) is lower than the average NTCP expected from the old technology (i.e. photons). To this end, patients