ESTRO 37 Abstract book

S1196

ESTRO 37

EP-2160 A practical method of undertaking QA for single Isocenter stereotactic treatment of Oligometastases. A. Jaganathan 1 , S. Fazlic 1 , H. D'Souza 1 , H. Weatherburn 1 1 Cancer Centre London, Physics, London, United Kingdom Purpose or Objective In this study we demonstrated a practical method of implementing Accurate QA for single Isocenter stereotactic radiosurgery (SRS) treatment of multiple metastases using an Octavius 1500 array detector. This is an alternate to using SRS 1000 array detector with the Octavius 4D system. Material and Methods The OCTAVIUS 4D system is designed to accommodate variable arrays such as Octavius 729, 1500 & 1000 SRS. The SRS 1000 is widely used for smaller lesions in SRS and SABR treatment for its highest spatial resolution in irregular field and the regions in steep dose gradients. However the maximum field size for this detector array is 10x10cm 2 which is not practical for multiple metastases with single isocenter where the two lesions spaced more than 10cm. As an example here, a single isocentre plan (Figure.1) has been produced in Monaco v5.1 treatment planning system (TPS). In conjunction with PTW verisoft merge function, Octavius 1500 array system has been used as a pre- treatment QA for single isocenter stereotactic treatment of multiple metastases. The measurements were performed on Elekta VersaHD linear accelerator equipped with high-definition MLC, using 6MV dynamic conformal arc therapy (DCAT). Furthermore, the accuracy of the results has been verified with EBT3 Gafchromic film. The film is sandwiched between the rotational unit and the polystyrene plate (replacement for detector unit) to fit in the system with reproducible geometry.

Conclusion The Octavius 1500 array system is good tool for the single Isocentric with multiple metastases pre-treatment verification for the SRS/SABR treatments without compromising the quality of plan evaluation. The single isocentre treatment considerably reduces the treatment time when compared to two isocentre plans. EP-2161 Optimizing preclinical research by using a data management platform L. Persoon 1 , S.J. Van Hoof 2 , P.V. Granton 2 , H. Beunk 1 , J.W. Doosje 1 , F. Verhaegen 3 1 ICT Group N.V., Healthcare, Eindhoven, The Netherlands 2 SmART Scientific Solutions B.V., N/A, Maastricht, The Netherlands 3 MAASTRO clinic, Department of Radiation Oncology, Maastricht, The Netherlands Purpose or Objective Radiobiological preclinical in vivo research is rapidly gaining interest as recent technological advances have produced equipment which can precisely irradiate targets and use advanced onboard image-guidance, mimicking a clinical environment. The goal of preclinical studies is to translate the result to clinical applications/trials. However, one of the main impediments is the data management of small animal research studies. This was recognized by an ESTRO ACROP workgroup, which recently advised that advanced data management platforms are necessary for preclinical research. Currently these data management platforms are absent. Such a platform should be capable of: 1) handling large volumes of data from many different sources; 2) integrating with preclinical systems (e.g. treatment planning systems); 3) supporting plug-ins for outcome prediction models; 4) managing the workflow of animal experiments, 5) reporting of the study results 6) track the animals during preparation and the entire project. The work presented here describes the development of a data management platform for pre-clinical research. Material and Methods A platform is developed implementing an adapted DICOM RT 2 nd gen. course model, capable of storing both DICOM and non-DICOM data. Furthermore the DICOM suppl. 187 for storing small animal acquisition context is supported. Figure 1 shows a schematic overview of the architecture of the platform. The platform entails:1) a study workflow manager, researchers should be able to create a custom study time-line to plan and prepare their experiment; 2) a data manager keeping track of all the data produced throughout the study; 3) a storage manager, keeping track of the physical location of the data produced. For each study, a simple workflow consisting of the following steps: 1) CT image acquisition; 2) treatment planning; 3) treatment delivery was created. The imaging data and treatment delivery was executed on an image-guided precision irradiation platform (X-Rad 225Cx; PXi, CT, USA), while the treatments plans were produced by SmART-ATP (PXi & SmART Scientific Solutions, Maastricht, NL). For the storage of the study data the platform supports a cloud based solution.

Results For analysis, 3D gamma function was accessed with 3mm/3% and 2mm/3% tolerance limits with a low dose threshold of 10%. Dosemap from the TPS was compared with single and merged measurements. In 3mm/3% criteria the percentage of passing points for merged compared to single measurement was 98.0% to 97.1% and for the 2mm/3% criteria the percentage of passing points was 93.5% to 93.3%. Although there is no significant difference in these g function, while evaluating dose levels (80-100%) the 80% of voxels has not met the passing criteria. For merged measurement the overall passing rate of voxels is significantly higher 81.1% to 70.3 % for 85% isodose level for 2mm/3% (Graph.1) and it gives more information about dose gradient. The measured fluence in coronal plane is compared with the film and shows a good agreement with the planned dose distributions.