ESTRO 38 Abstract book

S301 ESTRO 38

treated with VMAT between February and July 2018 were analyzed. These orders were categorized based on the following criteria: change of body contour, gap between skin and bolus (when used), tumor progression or inflammation of healthy tissue, tumor regression, shift of the target, tracheotomy performed after the reference computed tomography (CTref) images, teeth extraction after the CTref, second opinion on matching or other. For these criteria, frequency and follow-up action (i.e. no action required, new CT and plan adaptation) were scored.

Abstract text Purpose

The study assessed the impact of incorporation radiation therapist (RTT) into radiation oncologist RO team in Radiotherapy Wards. We intended to estimate the efficiency of workflow improvement and to investigate whether this would reduce the time gap between the preparation and the start of treatment. Material and Methods For one year RTT worked as a member of interdisciplinary team in two independent Wards. During the first six months selected RTT had worked strictly with RO at Radiotherapy Ward 1 (WR1) and focused on coordination and treatment preparation of patients with oesophagus, stomach, prostate and H&N cancer. In the second half of the year RTT managed patients with H&N and prostate cancer in the Radiotherapy Ward 2 (WR2). The main responsibilities were as follows: 1.participation in the morning report, 2. making an appointment and educating the patient, 3. coordinating the different phases of preparation for radiotherapy (RT) including: initial simulation, initial computed tomography (iCT) and virtual simulation, contouring of organs at risk (OAR), initial verification of treatment plans. Results Mean reduce of time from iCT to intent order was 1 day comparing to period without RTT. Mean time from intent order to initial simulation was > 4 days and from intent order to beginning of the treatment > 5 days. There was no statistically significant time reduction at that point. Average contouring time of OAR’s for RTT was 92 min for stomach 115 min for oesophagus case and 81min for prostate and 129 min for H&N cases. In the period when RTT coordinated and managed the radiotherapy pathway the number of treated patients increased by 23% and 11% in WR1 and WR2, respectively. Conclusions Cooperation with RTT results in reduced time of patient's preparation for radiotherapy and increased number of treated patients. PV-0574 Evaluation of a clinical decision support protocol during radiotherapy for H&N cancer patients F. Rodrigues Sousa 1 , Y. Jourani 2 , M. Somoano 1 , T. Dragan 1 , S. Beauvois 1 , D. Van Gestel 1 1 Institut Jules Bordet - Université Libre de Bruxelles, Radiotherapy, Brussels, Belgium ; 2 Institut Jules Bordet - Université Libre de Bruxelles, Medical Physics, Brussels, Belgium Purpose or Objective During radiotherapy (RT) treatment, variations such as patient weight loss, tumor regression and diminution of the volume of organs at risk (OARs) are likely to occur. These variations may result in changes in the dose distribution with a risk of overdose to the OARs which cannot be compensated for by a simple rigid repositioning. In order to more easily prioritize these variations according to their potential impact, an action level protocol (ALP) has been put into practice as a clinical decision support system (CDSS). In this study we analyze whether the used ALP criteria are adequate and clinically useful for adaptive planning and whether further optimization of the protocol can reduce the workload. Material and Methods An ALP (Figure 1) based on online provided papers was designed in an in-house developed informatics tool through collaboration between physicians, physicists and RTTs. All CBCT review orders from head and neck patients Poster Viewing: Poster viewing 11: Novel strategies in IGRT

Results In the 50 patients, our protocol resulted in 397 review orders: the majority (372; 94%) did not require any further action after investigation; in 17 cases (4%), a new CT scan was made; and in 7 cases (2%), a plan adaptation was done. The latter was seen in categories R5, R8, R9, R12, R13 and R14 (Figure 2). Clinically relevant indicators of potential adaptation were mostly found in time, i.e. in the OAL rather than in the RAL. CBCT review orders regarding shift of the target (within the PTV; R7) were most often reported, but required hardly any further action. Therefore we could safely decrease the action level of this criterion from an orange action level (OAL) to a yellow action level (YAL; Figure 1), reducing the radiation oncologists (ROs) workload by 57%.

Conclusion Our action level protocol has been proven adequate for identifying patients in need of adaptive re-planning, but it also led to many false alerts. The revised and optimized protocol leads to a reduction of 57% in the workload. PV-0575 Is diaphragm dome or bone fusion adequate to IGRT in liver-SBRT compare to fiducial markers? C. De la Pinta Alonso 1 , D. Sevillano 2 , R. Colmenares 2 , M. Martín 1 , C. Vallejo 1 , E. Fernández-Lizarbe 1 , S. Barrio 3 , V. Pino 3 , J.A. Rojo 3 , S. Sancho 1 1 Hospital Ramon y Cajal, Radiation Oncolo gy, Madrid, Spain; 2 Hospital Ramon y Cajal, Medical Physics, Madrid, Spain; 3 Hospital Ramon y Cajal, Radiotherapist, Madrid, Spain Purpose or Objective Stereotactic body radiotherapy (SBRT) in liver tumours is increasingly being used to treat primary and metastatic tumours. The purpose of this study was to compare the liver motion variability between using implanted fiducial markers as surrogates and alternatives methods with diaphragm dome or bone registration. We analyzed in this abstract our preliminary results. Material and Methods