ESTRO 38 Abstract book

S607 ESTRO 38

lost, ensuing repeated CT simulations and planning, incurring treatment delays, increased costs and impact on logistics and manpower. An invisible ultraviolet (UV) tattoo ink has been used as an alternative to tattoos. Landeg et al. [1] previously reported no significant inter-fraction setup reproducibility deviation and improved patients’ personal body image. However, the acceptability and reproducibility of UV tattoo ink on Asians who differ in skin pigmentation and cultural sensitivity as compared to Caucasians is unknown. We conducted a pilot study to assess the feasibility of replacing Indian ink with UV ink in our female breast cancer patients undergoing RT. Material and Methods 5 patients were enrolled in this prospective study. Each patient was given 2 conventional dark ink and 2 invisible UV ink tattoos. During treatment, the given tattoos were used to align to setup treatment field borders. Routine X- ray verification was used to confirm RT position. The visibility of UV tattoos were assessed during each RT fraction. A body image survey [2] was used to assess patients' acceptance of each ink type. This was administered at 3 time points (CT simulation, last week of RT and 6 weeks post-RT). An in-house staff satisfaction survey was administered once to the Radiation Therapists (RTTs) to assess their perception of the UV tattoos and their use in RT positioning. Results At ‘CT simulation’, 3 out of 5 (60%) patients were apprehensive about the impact of the tattoos on their body image and felt conscious about their appearance. However, post-RT, 100% of the patients were satisfied with the appearance of the UV tattoos and did not feel less attractive physically/sexually or less feminine. At post-RT, 4 out of 5 (80%) patients were satisfied with their body with respect to the UV tattoo and did not feel conscious about their appearance, found no difficulties looking at their naked self and did not intentionally avoid people. The UV tattoo ink posed minimal risk of infection or allergy as none of these events were observed. 12 RTTs responded to the staff satisfaction survey. All of them found it easy to locate the UV tattoos and recommended its use in future breast cancer patients. Although 92% of RTTs felt that UV tattoos did not affect the total time taken for patient setup, 42% indicated more time is needed to locate them. Nonetheless, most commented that invisible ink is aesthetically acceptable and can improve patients’ confidence. In addition, some felt that it would be valuable for patients with darker skin pigmentation. Conclusion From this feasibility study, we conclude that the invisible ink is well accepted by the breast cancer patients and RTTs. PO-1094 Use of an individual abdominal corset in patients with upper-GI tumors treated with proton therapy J. Thiele 1 , S. Schneider 2 , C. Valentini 3 , F. Lohaus 3 , S. Sarah 4 , D. Haak 1 , M. Krause 5 , A. Hoffmann 6 , E. Troost 5 1 University Hospital and Faculty of Medicine Carl Gustav Carus- Technische Universität Dresden- Dresden- Germany, Department of Radiotherapy and Radiation Oncology, Dresden, Germany ; 2 University Hospital and Faculty of Medicine Carl Gustav Carus- Technische Universität Dresden- Dresden- Germany, OncoRay - National Center for Radiation Research in Oncology- Dresden- Germany- Helmholtz-Zentrum Dresden - Rossendorf- Institute of Radioo, ; 3 University Hospital and Faculty of Medicine Carl Gustav Carus- Technische Universität Dresden- Dresden- Germany, Department of Radiotherapy and Radiation Oncology- OncoRay - National Center for Radiation Research in Oncology- Dresden- Germany, Dresden, ; 4 University Hospital and Faculty of Medicine Carl Gustav Carus- Technische

Universität Dresden- Dresden- Germany, OncoRay - National Center for Radiation Research in Oncology- Dresden- Germany- Helmholtz-Zentrum Dresden - Rossendorf- Institute of Radioo, ; 5 University Hospital and Faculty of Medicine Carl Gustav Carus- Technische Universität Dresden- Dresden- Germany, Department of Radiotherapy and Radiation Oncology- OncoRay - National Center for Radiation Research in Oncology- Dresden- Germany- Helmholt, ; 6 University Hospital and Faculty of Medicine Carl Gustav Carus- Technische Universität Dresden- Dresden- Germany, Department of Radiotherapy and Radiation Oncology- OncoRay - National Center for Radiation Research in Oncology- Dresden- Germany- Helmholt, Purpose or Objective The irradiation of tumors, which are subject to respiration-induced motion is challenging for pencil beam scanning (PBS) based proton therapy due to the interplay effect and the temporally varying tissue densities along the beam path. Here, we report on the feasibility, tolerability and setup reproducibility of an individualized immobilization device for patients with tumors in the upper abdomen, who are treated with PBS. Material and Methods Since January 2018, nine patients with tumors in the upper abdomen (pancreas, liver and gall bladder) have been treated with PBS at our department. All patients eligible for this study underwent the following procedure within 10-days: (1) intra-tumoral implantation of three fiducial markers for target localization, (2) design of an individualized abdominal corset for motion reduction by abdominal compression, (3) abdominal MRI scan with intravenous contrast agent (c.a.) for target volume definition and tumor motion quantification, and (4) 4D-CT scan with c.a. for treatment planning. CT simulation and irradiation was performed with a vacuum mattress (Fig.1). Before each treatment fraction, the position of the target volume was verified with orthogonal X-ray imaging. First, a 2D/2D match with the DRRs was performed and then the position of the fiducial markers was verified (tolerance level: 3-5mm). In case this tolerance level was exceeded, a CT scan was performed in-room and the dose distribution was recalculated for plan comparison; in case of clinically relevant changes in the dose distribution, a new plan was calculated.