ESTRO 36 Abstract Book

S546 ESTRO 36 2017 _______________________________________________________________________________________________

used for radiotherapy and to eliminate the errors caused by curvature change. Material and Methods With the agreement of institutional review board, 71 head and neck patients were enrolled and randomly assigned to use different pillow for either primary or postoperative RT. The three different pillows including conventional pillow (CP, Silverman Headrests, CIVCO, medical solution), customized pillow with alpha cradle (AC, Smithers Medical Products, Inc. ), and Moldcare Head Cushion pillow (MP, Alcar Co, Inc.). All patients used head and shoulder mask for fixation. Daily on-board image (OBI) was acquired for evaluation and correction of set-up error. Change of curvature was measured by the movement of the vertebral body of first (C1) and 5 th (C5) cervical spine, comparing to the location on digital reconstructed image from CT simulation. Results Of all patients accrued, 34 patients received surgery and postoperative radiotherapy, and 13, 11, and 10 patients used CP, AC, and MP respectively. Thirty-seven patients received primary radiotherapy without surgery, and 14, 11, and 12 of them used CP, AC, and MP respectively. There were 1633 OBI acquired. In postoperative RT group, the absolute movement of C1 were 0.07±0.03 cm, 0.07±0.03 cm, and 0.09±0.03 cm, when CP, AC, and MP was used, respectively (p> 0.05). In RT group, the absolute movements of C1 were 0.07±0.03 cm, 0.06±0.02 cm, and 0.08±0.08 cm, when CP, AC, and MP were used, respectively (p> 0.05). In comparison the movement of C5, the absolute movements were 0.15±0.04, 0.21±0.07, and 0.16±0.72, when CP, AC, and MP was used in postoperative RT group, respectively (p> 0.05). In primary RT group, the absolute movements were 0.23±0.09, 0.14±0.05, and 0.15±0.03, when CP, AC, and MP was used, respectively. The movements of C5 in patients who used AC (p = 0.048) or MP (p = 0.05) were significant lower than patients who used CP in primary RT group. Conclusion Customized pillow could reduce setup error in patients who received primary radiotherapy but not postoperative radiotherapy. PO-0999 Control of rectal volume with Kampo formula during prostate radiotherapy: A prospective study J. Kobayashi 1 , T. Tahara 2 , Y. Matsuzaki 1 , Y. Ono 1 , J. Matsumoto 1 , H. Sato 1 , K. Onko 1 , Y. Kishimoto 1 , T. Tanino 2 , H. Sakaguchi 2 , N. Uchida 2 1 Tottori University Hospital, Radiology, Yonago, Japan 2 Tottori University Hospital, Radiation Oncology, Yonago, Japan Purpose or Objective During intensity-modulated radiation therapy (IMRT) for prostate cancer, volume and position of the prostatic gland, bladder and rectum should be kept stable to minimize adverse events such as radiation proctitis or rectal bleeding. For this purpose, keeping the rectal volume small is essential. Daikenchuto (DKT) is a traditional Japanese herbal (Kampo) formula used to treat patients with abdominal bloating or constipation and is reported to increase intestinal motility. DKT is composed of three medical herbs (ginger, ginseng radix, Japanese pepper) and maltose powder. The purpose of this study was to investigate the effect of DKT on rectal volume during prostate IMRT prospectively. Material and Methods The institutional review board approved this study and written informed consent was obtained from all patients. We divided consecutive 30 non-metastatic (cT1cN0 to cT3bN0) prostate cancer patients into two groups. 15 patients were orally administered 15 grams of DKT per day from one month before IMRT until the last day of the treatment (DKT group). The remaining 15 were not administered DKT (non-DKT group). The prescribed

radiation dose was 78 Gy in 39 fractions for 7.5 weeks to the prostatic gland and proximal one-third or entire seminal vesicle according to their stratified recurrence risk. Kilo-voltage computed tomographic image (KV-CT) by linear accelerator (Trilogy, Varian Co.) was taken for three-dimensional matching set-up before each treatment session. Each KV-CT was sent to a radiation treatment planning workstation (Pinnacle 3, Phillips Medical Systems Co.) and rectal volume of anal-sided 8cm length was then measured. Calculated rectal volumes of the DKT group were compared to those of the non-DKT group. Administration of laxative agent, tubal gas suction or colon irrigation was done depending on residual rectal content before radiation. Results Total of 1,170 KV-CT were evaluated. Rectal volumes of DKT and non-DKT groups were 48.79-63.46 (mean 54.69 +/- 4.00) cm 3 and 52.41-142.57 (mean 81.37 +/- 16.36) cm 3 , respectively (p < 0.01). Adverse effects associated with DKT use such as appetite loss, liver dysfunction or interstitial pneumonia were not noted.

Conclusion DKT appears to be useful in reducing rectal volume and intra-fractional volume variance which would help prevent radiation proctitis or rectal bleeding in prostate curative radiotherapy. Longer follow-up with a larger patient population is desired. PO-1000 Immobilisation systems for brain treatment: are individual head supports needed for stable fixation? S. Meessen 1 , F. De Beer 1 , P. Van Haaren 1 , D. Schuring 1 1 Catharina Hospital Eindhoven, Department of Radiation Oncology, Eindhoven, The Netherlands Purpose or Objective For stereotactic treatment of brain metastases, good fixation of the patient is necessary to enable the use of small PTV margins and reduce the volume of healthy brain tissue receiving high doses. These fixations should prevent significant intrafaction movement, and reduce the interfraction rotations. The purpose of this study was to compare three different fixation systems, two with individual head supports and one with standard head support, and to evaluate which of these systems was best suited for stereotactic brain treatments. Material and Methods Patients receiving brain RT were treated with either one of three different fixation systems (Orfit Industries, see figure 1): a hybrid mask combined with (a) an individual head support vacuum bag (n=20); (b) a Thermofit individual head support(n=17); (c) a standard 3D head support with cranial stop (n=10). All patients received a correction protocol and were imaged at least 3 times during the treatment course using an Elekta XVI CBCT, both before and at the end of the treatment fraction. All scans were registered on bony anatomy and translations and rotations were recorded and analysed. For the three