ESTRO 36 Abstract Book

S938 ESTRO 36 2017 _______________________________________________________________________________________________

prostate one, and chamber cavity volume is taken into account more carefully which enables to keep tight tolerances. Results Centres which participated in the previous run did not perform better than centres which participated for the first time in prostate audit. However, results were sufficient in all cases. There was not significant improvement in results with installations of new linac and TPS. Better MLC performance was observed but CT number to RED was still the problematic point. Differences in planning approaches can be seen. Weakest point for the head audit was the phantom positioning on the couch (despite using IGRT). Tolerances for film evaluation depend on the dose gradient in the direction perpendicular to the film plane. We use 95% or 90% (4%/3mm) for gamma index for prostate/ H&N or brain plans respectively. In future, pseudo-3D gamma analysis will be implemented. Conclusion It is not straighforward to identify the causes of deviations, especially when they lie within tolerance limits. Nevertheless, it is possible to identify systematic errors which might be vendor dependent, user dependent, or TPS dependent. These can help to optimise the national quality standard in radiotherapy. We recommend not to use rigid marks on phantom but let the centre apply their own fixation and positioning procedure. We recommend to include CT scanning process and identical „patient“ set- up procedure employing RTTs. When designing audit methodology, it is necessary to analyze pilot run results first and then optimise procedure dependent tolerances. This work has been supported by the project No. TB04SUJB001 and by the Ministry of Interior of the Czech Republic, project No. MV-25972-53/OBVV-2010. EP-1732 Treatment planning of dose escalation for anal cancer in the PLATO trial N.L. Abbott 1 , D. Christophides 2 , M. Robinson 3 , J. Copeland 4 , R. Adams 5 , M. Harrison 6 , M. Hawkins 3 , R. Muirhead 3 , D. Sebag-Montefiore 2 1 Velindre Cancer Centre, National Radiotherapy Trials QA group, Cardiff, United Kingdom 2 University of Leeds, Leeds Cancer Centre- St James University Hospital & Leeds CRUK Centre, Leeds, United Kingdom 3 University of Oxford, CRUK/MRC Oxford Institute for Radiation Oncology, Oxford, United Kingdom 4 University of Leeds, Clinical Trials Research Unit, Leeds, United Kingdom 5 Velindre Cancer Centre, Cardiff, United Kingdom 6 The Hillingdon Hospital NHS Foundation Trust, Uxbridge, United Kingdom Purpose or Objective P ersona L ising A nal cancer radiotherapy d O se (PLATO) is a complex integrated protocol, including ACT5 for high risk patients. ACT5 compares standard and dose escalated radiotherapy. As part of trial development a planning study was carried out by lead centres to determine the impact of dose escalation on OAR sparing. Following this study a benchmark planning case was selected and sent to fifteen UK centres as part of the radiotherapy quality assurance programme (RT QA), co-ordinated by the national QA group. These centres will randomsie the first 60 patients in a pilot phase of the trial. We report the results of the planning study and benchmark planning case with respect to achievable OAR sparing with ACT5 dose escalation.

Figure 2 screenshots of the app that will be released to our pilot group of patients in November 2016. Conclusion We have developed Opal, a smartphone app and web portal, for oncology patients at our comprehensive cancer centre. Opal provides patients with access to their PHI, appointment schedules, waiting room management, relevant just-in-time educational material and patient- reported outcomes questionnaires. Development is currently in the closed beta phase with testing provided by volunteers with fake electronic health records. We will release the app to a pilot group of radiation oncology patients in November 20 17, followed by general release to all radiation oncology patients in early 2017. Release of the app to all oncology patients is planned for the spring of 2017. EP-1731 What can reveal onsite end-to-end audit? The experience of national dosimetry audit group I. Koniarova 1 , I. Horakova 1 , V. Dufek 1 1 National Radiation Protection Institute, Department of Radiotherapy and X-ray Laboratory, Praha, Czech Republic Purpose or Objective National Radiation Protection Institute performs on-site audits in the Czech Republic. In total, 53 on-site end-to- end audits for prostate and 16 for H&N/brain radiotherapy were performed. Prostate case was verified in the national run for all centres using IMRT in 2013 and repeated for majority of centres with upgrade/installation of new linacs in 2014-2016. There was a pilot run with head phantom in 2016. Majority of results were within tolerances. All results were analysed to describe the most interesting findings and the weakest points. Material and Methods Absorbed doses with ionisation chambers and plane doses with EBT3 films were measured in the pelvic or head phantom. Following aspects can be assessed: unit calibration, TPS model accuracy for reference field, MLC accuracy, CT numbers to RED conversion in terms of its influence to dose, phantom geometrical offset at the couch, optimisation constraints, radiobiological plan parameters calculated from DVHs. Anthropomorphic phantoms (pelvic and head) with benchmark PTVs and OARs were used. Three sets of audit results were analysed: prostate audit national run, repeated prostate audit, H&N/brain audit pilot run. Methodology is applicable to C- arm linacs, Tomotherapy, Leksell Gamma Knife, and proton beams. H&N/brain audit is more complex than