ESTRO 36 Abstract Book

S158 ESTRO 36 2017 _______________________________________________________________________________________________

well as diffusion weighted (DW) and dynamic contrast enhanced (DCE) MR imaging. Voxel-based and regional correlation analysis of mutual parameter pairs showed moderate to low parameter correlations. However, on a patient-to-patient basis large variations were observed for most parameter correlations. Consequently, robust and accurate workflows and image acquisition protocols need to be identified in order to use multi-parametric functional PET/MR imaging in the future for adapted RT concepts in a clinical context. SP-0308 Metabolic and functional MRI integration for glioblastoma dose-painting trial. A. Laprie 1 1 Institut Claudius Regaud, Toulouse Cedex 09, France The ongoing spectro-glio trial (NCT01507506) is a phase III multicentric randomized trial for newly diagnosed glioblastoma. It has included 165 patients among the 220 planned. It compares arm A : STUPP protocol ( 60 GY + TMZ) with arm B that includes an additional SIB targeted at MR spectroscopic abnomalities ( CHO/NAA>2)+tumor bed at a dose of 72Gy/2.4Gy In this presentation we will discuss the original modalities, the difficulties met and the solutions found for the particularity of this trial : multicentric use of 3D MR spectroscopic imaging developement of an innovative technique of integration of MR spectroscopic imaging to RT-scan centralized delineation of arm B patients - online quality control of dosimetry in arm B patients database developement - analysis techniques of this large prospective database of anatomic, perfusion, diffusion and spectroscopic imaging of glioblastoma.( follow-up every 3 months until relapse) -preliminary imaging results SP-0309 Plan of the day and dose-escalation for bladder cancer (RAIDER Trial) H. McNair 1 1 The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, Sutton, United Kingdom The major challenge in delivering accurate radiotherapy to the bladder is to compensate for the daily variation in organ size, shape and position. This change is mainly due to differing degrees of bladder filling and can be influenced by change in rectal volume. The plan of the day approach has the potential to improve outcomes by improving target coverage and decrease the dose to bowel. However the unpredictable nature of bladder filling and changes in organ dimensions require confident and timely decision making for treatment delivery. This is of particular importance when the does to the tumour bed is escalated. This presentation will discuss the importance of achieving a representative reference image and the practicalities of the patient maintaining a consistent drinking protocol. Clinical examples will be used to illustrate common imaging problems with appropriate decision making, in particular when not to proceed to treatment. The importance of staff training and maintaining competency to achieve consistent image selection will also be discussed. Acknowledgements: Emma Hall, Robert Huddart and Shasita Hafeez and the RAIDER trials team. Radiotherapy Trials Quality Assurance (RTTQA) team. We also acknowledge funding to the NIHR Biomedical Research Centre at The Royal Marsden and The Institute of Cancer Research. Research at The Institute of Cancer Research is also supported by Cancer Research UK under Programme C33589/A19727. In addition the national trial (RAIDER) was funded by Cancer Research UK (CRUK/14/016)

Conclusion In sum, independently of PBS delivery scenario, the treatment of liver tumours under free-breathing conditions is not recommended for motions over 10mm, even when applying large numbers of rescans. However, re-gating (LS5+GW5) is predicted to be sufficient to achieve acceptable 4D plan quality for all scenarios, even though synchrotron based delivery could have a significant added time cost in comparison to cyclotron based systems.

Symposium: Focus on ART: the clinical difficulties

SP-0307 Multi-parametri c functional PET/MR imaging for RT individualisation D. Thorwarth 1 1 University of Tübingen, Sectio n for Biomedical Physics- Department of Radiation Oncology, Tübingen, Germany Multi-parametric functional imaging using combined positron emission tomograph y and magnetic resonance (PET/MR) imaging may be highly beneficial for the assessment of tumour stage, size, therapy response and functional information before and during radiotherapy (RT) in order to guide not only geometrical but also biological adaptation during the course of RT treatment. This talk will discuss a number of issues, which might compromise the use of multi-parametric functional imaging in a clinical setting. In order to register functional PET/MR image data to the planning CT of an individual patient, tailored patient positioning devices and dedicated algorithms for PET attenuation correction with respect to the hardware components of the positioning aids are required. Furthermore, robust and accurate deformable registration strategies may be required to match PET/MR data acquired during RT to baseline imaging data. In addition, first results of a multi-parametric PET/MR imaging study in head-and-neck cancer (HNC) patients will be discussed. Here, [18F]FDG PET/CT images were acquired in addition to functional PET/MR data consisting of [18F]FMISO PET, anatomical T1- and T2-weighted as