ESTRO 37 Abstract book

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ESTRO 37

currently performed and which tools and criteria are used for comparison between planned and measured dose in order to understand the needs in this area. The EPTN WP5 on treatment planning system is addressing this topic as well and a dedicated questionnaire has been prepared. As such WP2 will not include patient specific verification questions on its survey but will profit from the results of WP5. 5) Dosimetry tools : as a results of the QA/equipment survey a database for dosimetry equipment used in particle therapy will be created and maintained. 6) Ocular treatments : dedicated working group on the dosimetry aspects of ocular treatments. The aims and status of activities of each working group will be presented with particular attention to the preliminary results of the QA/equipment survey. SP-0220 EPTN WP4: Image Guidance in Particle Therapy A. Hoffmann 1 , A. Bolsi 2 , M. Peroni 2 1 OncoRay - Center for Radiation Research in Oncology, Medical Radiation Physics, Dresden, Germany 2 Paul Scherrer Institute, Centre for Proton Therapy, Villigen, Switzerland Abstract text The finite range of a particle beam makes the dose delivered by particle therapy (PT) more sensitive to morphological (i.e. geometric and anatomical) variations than for photon therapy (XT). To reduce this range uncertainty, PT can benefit from incorporating image- guidance techniques in the treatment delivery phase. Currently, imaging guidance in particle therapy (IGPT) lags behind photon therapy (IGXT) as the translation of imaging tools and techniques from XT to PT is not always straightforward. At present, clinical IGPT mainly involves daily orthogonal kilovoltage (kV) X-ray imaging, which lacks soft-tissue contrast. Consequently, CT scans have been included to assess the impact of anatomical changes during the course of therapy (with schedules varying on a centre-by-centre basis). In some centres, in-room CT imaging is available both for positioning and for offline monitoring of anatomy changes. Recently, the ability to perform on-board cone-beam CT (CBCT) has come available on some systems. Although CBCT has been widely implemented for IGXT, for IGPT it is nowhere near a standardized approach. Moreover, the value of in-room CT versus CBCT has to be established. Given the lack of standardized procedures, most PT centres have developed their own strategies for IGPT, which is based on to their available infrastructure, technical implementation and delivery strategy. The need to cooperate among centres and exchange knowledge on IGPT as an integral part of modern image- guided radiation therapy has been acknowledged as being of importance to bring PT forward. Within ESTRO’s EPTN Task Force, the goal of working group on “ Image Guidance in Particle Therapy ” is to assess the current status of IGPT in clinical practice, to identify bottlenecks and challenges of IGPT, and to drive harmonization through guidelines based on consensus between the European centres. Moreover, an inventory of current research activities in IGPT will be provided, with the intent of facilitating translation of innovative techniques into clinical practice. Furthermore, a strategy proposal for future IGPT research that would require a European network of PT centres will be developed. As a first step, contact persons interested to participate in the IGPT-WP have been identified within 19 participating European PT centres. A survey on the status and future perspectives of IGPT has been filled out by all of these centres in February 2016. Topics covered in the survey include: patient immobilization, imaging for treatment planning, patient positioning and dose delivery, imaging for moving targets, research activities

and future perspectives of IGPT. Secondly, a first workshop of the IGPT-WP has been organized in 2017 with representatives of 12 PT centres. During this meeting, three sub-working groups have been defined based on body site: 1) brain, head and neck, 2) thorax, 3) abdomen and pelvis. The coordinators for the sub-working groups have participated in the analysis of the results of the questionnaire relevant to their field. A detailed evaluation of imaging requirements and methods for five workflow steps: a) simulation and planning, b) image guidance, c) treatment verification, d) treatment evaluation and adaptation, e) 4D imaging for moving targets is on-going work in each of the sub-working groups. In this contribution, the results of the survey will be summarized and the roadmap for the IGPT-WP will be presented. SP-0221 EPTN WP5: Treatment planning systems T. Lomax PSI, Switzerland Abstract text Particle therapy (PT) as cancer treatment, using protons or heavier ions, can provide a more favourable dose distribution compared to x-rays. While the physical characteristics of particle radiation have been the aim of intense research, less focus has been on the actual biological responses particle irradiation gives rise to. One of the biggest challenges for the radiobiology is the RBE, with an increasing concern that the clinical proton RBE of 1.1 is an oversimplification, as RBE is a complex quantity, depending on both biological and physical parameters, such as dose, LET, cellular and tissue radiobiological characteristics, and the endpoints studied. Most of the available RBE data is in vitro data, with very limited in vivo data available, especially in late-reacting tissues which provide the main constraints and influence the quality of life endpoints in radiotherapy. There is a need for systematic, large-scale studies to thoroughly establish the biology of particle radiation in a number of different experimental models in order to refine biophysical mathematical models that can potentially be used to guide PT. The aim of the EPTN WP6 is to form a network of research and therapy facilities. This would aim to standardise the radiobiological experiments, obtain more accurate predictive parameters than in the past. Coordinated research is required in order to deliver the most suitable experimental data. Abstract not received SP-0222 EPTN WP6: Radiobiology B.S. Sørensen 1 1 Aarhus University Hospital, Exp. Clin. Oncology, Aarhus C, Denmark

On behalf of the coordinators of WP6

Symposium: Mouse Cancer Clinic: models and modalities for precision imaging and radiotherapy in small animal models

SP-0223 State of the art and future developments of small animal imaging and radiotherapy platforms F. Verhaegen 1 , S. Van Hoof 1 , L. Schyns 1 , S. Yahyanejad 2 , B. Van der Heyden 1 , A. Vaniqui 1 , P. Granton 1 , L. Dubois 2 , M. Vooijs 2 1 Maastricht Radiation Oncology MAASTRO, Radiotherapy, Maastricht, The Netherlands