ESTRO 38 Abstract book

S3 ESTRO 38

important for RT planning. A baseline pre-treatment PET/CT is recommended. Smaller nodes that are not FDG- avid but seen on CT adjacent to FDG-avid nodes should be included. In masses seen on CT with partial FDG-uptake the entire mass should be included. Breathing control techniques are recommended for mediastinal treatment to reduce the doses to the critical structures. Teaching Lecture: The role of postoperative radiotherapy in endometrial cancer: what have we learned of the PORTEC trials? SP-0005 The role of postoperative radiotherapy in endometrial cancer: what have we learned of the PORTEC trials? C. Creutzberg 1 1 Leiden University Medical Center LUMC, Department of Radiotherapy, Leiden, The Netherlands Abstract text In this presentation, the current evidence and recent developments in risk-based adjuvant treatment for endometrial cancer will be discussed, reviewing the data from the PORTEC-1 and PORTEC-2 trials which have been pivotal in determining the role of radiation therapy, especially vaginal brachytherapy, in (high)intermediate risk endometrial cancer. The PORTEC-3 trial focused on the 15-20% of women with high-risk endometrial cancer (stage IB grade 3 and stage II-II endometrial cancers, and stage I-III non-endometrioid cancers), investigating the efficacy of combined adjuvant chemotherapy and radiation therapy, showing that radiation therapy alone is still standard treatment for stage I-II disease, while combined adjuvant treatment should be considered for women with stage III disease and those with serous cancers. Data on toxicity and quality of life from these trials are essential for shared decision making. The PORTEC-4a trial builds on the recent knowledge on molecular characteristics of endometrial cancer and investigates the role of an integrated molecular profile to determine adjuvant treatment in high-intermediate risk disease, aiming to reduce overtreatment by sparing the expected 50% with a favourable profile adjuvant brachytherapy, while optimizing outcomes for the 5-10% with an unfavourable profile by using pelvic radiotherapy. Results of the pilot phase have shown the determination of the molecular factors within 2 weeks to be feasible in clinical practice. The PORTEC-results will be put into perspective of results from other recent randomised trials, and future developments will be discussed. SP-0006 Gating and breath-hold techniquess in Radiation Therapy M. Aznar 1 1 The University of Manchester, Division of Cancer Sciences, Manchester, United Kingdom Abstract text This teaching lecture will summarise the upcoming ACROP guidelines on the practical implementation of breath hold techniques in different clinical sites (breast, lung, lymphoma, abdomen). The similarities and differences with gating approaches will be highlighted and special focus will be given to image guidance procedure (for planning purposes as well before treatment and during treatment). Teaching Lecture: Gating and breath-hold techniquess in Radiation Therapy

Teaching Lecture: Technology for precision small animal radiotherapy research: Optimal use and challenges

SP-0007 Technology for precision small animal radiotherapy research: Optimal use and challenges F. Verhaegen 1 , A. Vaniqui 1 , S. Van Hoof 1 , I.P. Almeida 1 , B. Van Der Heyden 1 , P. Granton 2 , J. Theys 3 , M. Vooijs 3 , L. Dubois 3 1 Maastricht Radiation Oncology Maastro, Clinical Physics Research, Maastricht, The Netherlands ; 2 Smart Scientific Solutions Bv, Maastricht, The Netherlands ; 3 Maastricht Radiation Oncology Maastro, Maastro Lab, Maastricht, The Netherlands Abstract text Two major recent developments have boosted radiobiology research in in vivo systems: (1) the development of high-precision image-guided photon irradiation platforms including treatment planning software, and (2) the development of ever more realistic disease models. These platforms have been developed mostly for cancer research, but can also be used for the study of other diseases e.g. in cardiology or neurology. To guide the users towards optimal use of this new technology, recently ESTRO issued ACROP (Advisory Committee on Radiation Oncology Practice ) guidelines 1 . These guidelines identified several challenges including: (1) what are the key technologies required to downscale clinical treatments into small animal models, (2) how to deal with target motion, (3) which imaging modalities should be integrated into the radiation platforms, (4) what are the optimal irradiation margins, (5) what is the accuracy and precision of small field dosimetry, (6) which methods should be developed to verify the dose distribution, (7) which imaging modalities should be used for treatment planning, given the evolving clinical scenarios, (8) what is the difference between high and low-energy photon irradiation. These novel platforms combine capabilities for precision irradiation with very small fields (e.g. in an arc), with various modalities of integrated onboard high resolution imaging. The platforms enable for the first time irradiation studies at the mouse/rat level, similar to the clinical standard of image-guided radiotherapy. These platforms include imaging modalities such as micro-cone beam CT, bioluminescent imaging (BLI), advanced targeting capabilities and a dedicated treatment planning system (e.g. SmART-ATP 2 ). Further developments at the research stage include orthotopic tumor models, novel BLI targeting, novel CT contrast media, dual-energy CT imaging, spectral CT imaging, phase-contrast imaging, intravital microscopy, microbeam technology, motion- gated therapy, motion-dependent dose calculations, dose painting, margin recipes, autodelineation of anatomical structures, non-coplanar beams, dynamic field collimators, dose verification systems, advanced phantoms, and a preclinical data warehouse. Furthermore, the first studies on precision irradiation of rodent models with proton beams have been published 3 . From the overview to be given in this lecture it is clear the research platforms are reaching a level of maturity which will facilitate translational research. Many more developments are expected in the near future. 1. Verhaegen et al. ESTRO ACROP: Technology for Precision Small Animal Radiotherapy Research: optimal use and challenges. Radiother Oncol, 126/3, 471-78, 2018 2. van Hoof et al. Development and Validation of a Treatment Planning System for Small Animal Radiotherapy: SmART-Plan . Radiother Oncol, 109, 361-6, 2013 3. Almeida et al. Exploring the feasibility of a clinical