ESTRO 36 Abstract Book

S398 ESTRO 36 _______________________________________________________________________________________________

worldwide use of IORT including patient selection criteria and treatment modalities and could represent a basis to design future clinical trials. PO-0755 Implementation of structural patient reported outcome registration in clinical practice I. Nijsten - van Riesen 1 , L. Boersma 2 , M. Brouns 1 , A. Dekker 3 , K. Smits 4 1 MAASTRO Clinic, Projectmanager Datacentre Maastro Clinic DCM, Maastricht, The Netherlands 2 MAASTRO Clinic, Director of Patient Care, Maastricht, The Netherlands 3 MAASTRO Clinic, Manager Research and Education, Maastricht, The Netherlands 4 MAASTRO Clinic, Manager of Datacentre Maastro Clinic DCM, Maastricht, The Netherlands Purpose or Objective Over the last years there has been an increasing focus on registration and national audits of quality indicators, with the assumption that insights into the quality of a certain treatment will increase outcomes. Within our radiotherapy (RT) institute we have set-up a structural outcome registration, where we first focussed on registration of toxicity, both reported by the doctor and by the patient. The reported toxicity was stored in a data warehouse including dashboards to evaluate toxicity on a population level, and to identify potential targets for improvements in the quality of care. The current study was done to investigate how we can directly improve individual patient care by re-directing the patient- reported outcome measures (PROMs) to the responsible radiation oncologist (RO). Material and Methods

discussing the high score in regular follow-up contact with the patient, to referring the patient to the GP, to making a note in the EPF. 90 Out of the 137 (66%) QNRs concerned symptoms between baseline to 3 months after RT; the other 34% concerned late toxicity. The time used by the RO to undertake action varied from 1 - 20 minutes, with an average of 5,8 and a SD of 4 minutes. Conclusion We found that re-directing the patient-QNRs to the responsible RO improved patient related quality of care, since actions were taken based on information the RO formerly did not acquire. However, the workload for the RO can significantly be diminished by only re-directing QNRs that are returned from 3 months after treatment, since most patients have their follow-up in the referring hospitals. Here PROMs have a substantial added value. The next step is to have the DWH automatically send an alert to the responsible RO. Poster: Physics track: Basic dosimetry and phantom and detector development PO-0756 Characterizing tissue equivalent materials used for an end-to-end QA phantom for MR-guided RT A. Steinmann 1 , D. Followill 1 1 UT MD Anderson Cancer Center Radiation Physics, Radiation Physics, Houston- TX, USA Purpose or Objective Tissue equivalent (TE) materials currently used to simulate tumor and surround tissues for IROC-Houston’s anthropomorphic head and thorax QA phantoms cannot be visualized on MR. The purpose of this study was to characterize “dual MR/CT compatible” TE materials that can be used in an end-to-end QA phantom for MR guided radiotherapy (MRgRT) modalities. Material and Methods Four materials were characterized for use as TE materials in a QA phantom for MRgRT modalities and were examined based on MR/CT visualization and dosimetric properties. These materials included soft tissue, lung and two potential tumor substitute alternatives. Materials were scanned on Siemens’ 1.5T using four sequences, which showed the materials visual contrast between T1 and T2 weighted images. Material’s attenuation data were collected using GE’s CT Simulator. Dosimetric properties were examined by constructing a 10x10x20 cm 3 PDD phantom that was divided into three sections: anterior, middle, and posterior. Anterior and posterior pieces were composed of polystyrene, whereas the middle section was substituted with the testing materials. EBT3 film was inserted into the phantom’s midline and was irradiated using Elekta’s Versa 6 MV beam with a prescription of 6 Gy at 1.5 cm and varying field size of: 10x10 cm 2 , 6x6 cm 2 , and 3x3 cm 2 . Relative film measurements were compared with a treatment plan. Two mini-phantoms were constructed out of the four previously studied materials that represented interfaces between tumor/soft-tissue and tumor/lung. Theses phantoms were fabricated into a 15x15x15 cm 3 cube, where the center-most represented a tumor with dimensions of 3x3x5 cm 3 . Two TLDS were inserted inside the tumor and EBT3 was inserted in the sagittal plane. With a prescription of 6 Gy at 1.5 cm, beam profiles were collected with and without a magnetic field from a 1.5T MR-Linac. Results The tested TE materials provided great contrasts amongst T1 and T2 weighted images, additionally, they showed attenuation comparable to their respective organ sites. MR/CT compatible lung and soft TE materials had HUs of - 685, and 20, respectively, whereas the two potential tumor alternatives showed HU values of -160 and 30. PDD curves were compared with IROC-Houston’s conventional lung and soft tissue substitutes. Soft

In our regular outcome registration, we score acute toxicity both by the RO and patient, whereas late toxicity is mainly scored by the patient. For the PROMs we handout validated – tumor group specific - questionnaires (QNRs) at baseline. Subsequently we sent out the QNRs at 3 weeks after the end of RT, 3, 6 and 12 months after RT, and thereafter yearly until 5 years after RT. For the current study we manually selected all QNRs scoring ≥ grade 3 symptoms on any item during 2 months. The selected QNRs were sent to the responsible RO by e-mail. The RO reported his/her subsequent actions: 1) Making a note in the Electronic Patient File (EPF); 2) contacting the patient to decide whether analysis and/or treatment of the symptoms was required, or 3) no action. Finally, the RO reported how much time the actions had taken. The type of undertaken actions and the required time was analysed per time-point of the QNR, and per tumor type. Results All received QNRs during the set period, in total 459, were screened; in 137 (30%) ≥ grade 3 symptoms were reported on any item, which varied between the tumor groups (figure). In 20% of the cases, spread evenly (relatively) between short term and later time points, the RO undertook some additional action, which varied between