ESTRO 36 Abstract Book

S982 ESTRO 36 2017 _______________________________________________________________________________________________

Seventy-four H&N cancer patients were randomized to three different types of immobilized pillow: 28 for routine pillow (Silver Headrests, CIVCO, medical solution), 23 for home-made customized alpha cradle pillow and 23 for Moldcare pillow. On–board images (OBIs) during the first 23 treatment fractions were registered and fused with the digitally reconstructed radiographs (DRRs). The angular displacement of first to fifth cervical vertebrae were recorded. Results There was no significant difference of the C1-C5 angular displacement in three different types of pillows with 2.79 ± 1.72 degrees in the routine pillow group, 2.54±1.68 degrees in home-made customized alpha cradle pillow group, 3.17±2.32 degrees in Moldcare pillow group. Conclusion The patients in home-made customized alpha cradle pillow group had smallest neck angular displacement. However there were no significant difference and the reproducibilities of all three pillow types were good. Further evaluation about the clinical use of customized pillows is needed. EP-1817 Breast set-up: Assessing two immobilization systems V. Lancellotta 1 , A.M. Tini 1 , S. Saccia 1 , S. Trinari 1 , S. Dazzini 1 , G. Verzini 1 , N. Mearelli 1 , V. Bini 1 , A. Cavalli 1 , E. Perrucci 1 , C. Aristei 1 1 Ospedale Santa Maria della Misericordia, Radiation Oncology, Perugia, Italy Purpose or Objective In breast cancer radiotherapy, an optimal patient set- up is essential to reduce the gap between personalized treatment planning and uncertainties in irradiation administration. In fact, several factors worsen reproducibility, with the most important being poor patient immobilization and lack of a quality assurance system at all steps of the radiotherapy procedure.The aim of our study was to investigate whether the breast board or the arm shuttle provided the best support for a correct patient set-up during irradiation to for breast cancer. Material and Methods Between November 2012 and December 2014, 28 women, median age 62 years (range 34-88) underwent RT to breast/chest wall plus level III and IV lymph nodes (2 Gy single dose in 25 fractions for a total dose of 50 Gy ). Each patient was placed in the same position i.e. supine with arms raised. Thirteen were supported by a non-inclined breast board and 15 by an arm shuttle. The breast board has several adjustable features to allow for the manipulation of patients arms, wrists, head and shoulders. Furthermore, the presence of head and neck supports in different heights and contours to attain the desired head angulation and/or neck position. Multiple head rest positions in the arm-shuttle provided flexible positions for the head and arms without different heights and contours to attain the desired head angulation and/or neck position. Helical tomotherapy was used to treat all patients. HT planning parameters were: 5 cm field width (FW), 0.287 pitch, and 2.7 - 3 modulation factor (MF). Daily use of CT-MV image-guided RT corrected set- up errors. For each patient, we reported the pitch, yaw and roll values and the x, y and z axis displacements. Statistical analysis used the Mann-Witney test. Results Table 1 reports pitch, yaw and roll averages and the average displacement on the X, Y and Z axes with the breast board and arm shuttle as well as the significant differences which emerged from the statistical analysis. Conclusion Compared with the arm shuttle, the breast board provided a better set-up in breast cancer patients undergoing HT irradiation to the breast/chest wall plus draining

nodes .Since these results are linked to breast board configuration , its use is now standard in our RT Centre.

Electronic Poster: RTT track: Imaging acquisition and registration, OAR and target definition

EP-1818 The rate of a doctor’s progress in a learning curve in delineation of hippocampus M. Konopka-Filippow 1,2 , E. Sierko 1,2,3 , D. Hempel 1 , R. Maksim 1 , T. Filipowski 1 , E. Rożkowska 1 , S. Jelski 4 , B. Kasprowicz 4 , E. Karbowska 4 , N. Samołyk 1 , M.Z. Wojtukiewicz 3 1 Comprehensive Cancer Center in Bialystok- Poland, Department of Radiotherapy, Bialystok, Poland 2 Medical University of Bialystok- Poland, Department of Oncology, Bialystok, Poland 3 Comprehensive Cancer Center in Bialystok- Poland, Department of Clinical Oncology, Bialystok, Poland 4 Comprehensive Cancer Center in Bialystok- Poland, Department of Radiology, Bialystok, Poland Purpose or Objective Brain radiotherapy (RT) is associated with damage of neural progenitor cells situated in subgranular zone of the hippocampus, which causes neurocognitive decline. Sparing hippocampus during cranial RT could avoid this complication in the group of cancer patients and improve their quality of life (QoL). Accurate hippocampus contouring is an essential for appropriate brain RT planning with sparing this structure and its an prerequisite of quality assurance in RT. Material and Methods Ten doctors (7 radiation oncologist and 3 radiologists) delineated left and right hippocampus (LH and RH, respectively) on the 10 patient’s virtual axial images of CT brain fusion with the T1 sequence of MRI (1mm) according to the RTOG 0933 atlas recommendations. Two hundred contours of hippocampus were achieved. Deviations in the spatial localization of the structure were described in the three directions: right-left (X), cranio-caudal (Y), forward- backward (Z) in relation to the most adequate contoured hippocampus according to RTOG atlas references, which was delineated by an experienced radiation oncologist. Results Variability of hippocampus body contouring concerned: the spatial localization, shape, volume and the dimension of the hippocampus in the X, Y and Z axes. The largest differences were noted in the first three contoured cases: the Z-axis deviation exceeded 5 mm in more than half of hippocampus contours and hippocampal volume were larger than in later defined seven cases. The volume of LH in more than half hippocampus contours was slightly bigger than the RH (1.9 cm 3 vs. 1.8 cm 3 ). Most differences in contouring of hippocampus ware observed in the area of posterior horn of the lateral ventricle. Contrary, a large number of hippocampal outlines overlapped with each other near brainstem and anterior horn of the lateral ventricle. The average dimension of the hippocampus were 1.7 cm and 0.9 cm in the Z and X axes, respectively. Conclusion The proper contouring of hippocampus is difficult for the beginner’s physicians. The training in delineating this organ at risk under the supervision of experienced radiation oncologist is strongly needed to achieve optimal results in hippocampus sparing procedure, which in consequence would result in improving QoL of the patients.