Abstract book - ESTRO meets Asia

S84 ESTRO meets Asia 2018

final optimization parameters. Plan isocenter is always placed at the GTV center of mass. The SBRT prescription was for 1800 x 3 cGy with goals and constraints per RTOG 1021 verified automatically using Radformation ClearCheck software. VMAT planning was performed with Varian Eclipse for TrueBeam delivery with Standard Imaging LinacView log-based monitoring. Planning review including Sun Nuclear ArcCHECK measured patient specific quality assurance were easily completed before scheduled treatment. Repeat imaging (Img_i) is scheduled for each treatment fraction i = 1, 2, 3. Varian Velocity Deformable Image Registration (DIR) software from Img_0 to Img_i is used to create GTV_i. Remaining structures are created using expansion or auto contouring tools. Daily treatment plan Pln_i optimization is performed using the same constraints as for Pln_0. Minor adjustments can be made after automated ClearCheck review. The acceptable plan undergoes pre-treatment LinacView QA and the patient treatment can begin immediately. Results As shown in the attached figure there was a 15% change in right lung volume with clinically significant changes in both position and shape of the GTV. DIR of Img_0 to Img_1 applied to GTV_0 was able to correctly contour the new target. Similarly other relevant structures were also identified and expanded to create the required planning regions of interest.

intensity projection (MIP), with organ at risk contoured on average intensity projection (AIP), and 5mm margin added for PTV. Patients were treated on linear accelerator (Varian, Novalis TX, USA), with no respiratory gating. Patients had CBCT verification prior to each arc. Tolerance for set up was set at 2 mm. Dose given was 50-60Gy in 5-8 fractions of 7.5-11Gy treat alternate days for 5 patients. Patients had a CT prior to treatment as well as a follow up CT one month later, and assessment for toxicity. Results Average metastasis volume was 6.42 cm 3 pre-treatment and the average one month post treatment volume was 2.13cm 3 . 2 patients missed the appointment for CT, but instead had the CT reassessment done in 3-4 months, and the average volume was 1.55cm 3 . Overall, there was no acute toxicity reported at one month post-treatment. With the median follow up period of 18 months from the date of SBRT, all the lesions that have received SBRT are still in remission. However, 2 patients have disease progression at the region out of SBRT field. The other 3 patients are still progression-free. All the patients that have received SBRT, none reported any SBRT related complications up to the date of last follow up. Conclusion From our early experience, SBRT is a safe and effective method to treat oligometastatic lung tumour, and the study will be pursued PO-208 High dose radiotherapy improved local progression free in patients with inoperable stage III NSCLC Y.I. Kim 1 , C. Moon-june 1 , K. Jun-Sang 1 , K. Sub 1 , K. Ki- Hwan 1 1 Chungnam National University Hospital, Radiation Oncology, DaeJeon, Korea Republic of Purpose or Objective Local failure is common after concurrent or sequential chemo-radiation therapy for non-small cell lung cancer (NSCLC). Hypothesizing that a higher dose of radiation to the gross tumor volume (GTV) might increase local control of advanced NSCLC. We investigated whether high-dose radiation improved local control in patients with stage III NSCLC. Material and Methods Sixty-four patients with stage III NSCLC were treated with three-dimensional conformal radiation therapy. Clinical target volume (CTV) contains GTV, plus a margin which is determined to consider the anatomic structure. Elective nodal irradiation had not been allowed. Patients with NSCLC were received high dose radiotherapy, 74Gy at CTV. The volume of lung receiving at least 20Gy (V20) is restricted to 25% because of lung toxicity. Acute and late toxicities were scored per the Common Terminology Criteria for Adverse Events version 4.0. The primary endpoint was overall survival (OS) and local progression free survival (LPFS) the length of time during and after the treatment of a disease that a patient lives with the disease but it does not get worse. All analyses were done by intention-to-treat. Results Between Feb. 08, 2011 and Feb. 22, 2016, 64 patients received high dose radiotherapy and/or chemotherapy. 8 patients (12.5%) did not complete full dose radiotherapy. 3 patients stopped treatment voluntarily, 3 patients due to tumor progression during radiotherapy, and 2 patients dropped out of the treatment side effects – 1 neutropenia, 1 general weakness. Median follow-up was 14.6 months (1.2-51.6). Median OS was 20.0 months (1.2-65.6, and 3- year OS was 50.5%. Median LPFS was 15.7 months (1.2- 57.0), and 3-year LPFS was 54.5%, retrospectively. Only one patient (1.6%) had grade 5 radiation induced

Application of the original Plan_0 dose volume constraints on daily Img_1 GTV_1, PTV_1, and ring structures resulted in an acceptable plan within one iteration. Only minor improvements were possible with repeated optimizations. Conclusion Since there is a high probability of geometric changes in SBRT lung patients with pleural effusion we have developed a comprehensive strategy encompassing an easily adaptable primary plan combined with scheduled imaging suitable for rapid treatment at each fraction. PO-207 SBRT for Patients with Lung Oligometastasis at University Malaya Medical Centre-An Early Experience F.Y. HENG 1 , X.Y. Ee 1 , J. Zulaikha 1 , W.L. Jong 1 , A. Adlinda 1 , G.F. Ho 1 1 Clinical Oncology Dept. University of Malaya Medical Ce ntre, Clinical Oncology, Kuala Lumpur, Malaysia Purpose or Objective We retrospectively evaluated the clinical outcomes of 5 patients with oligometastatic lung tumours who underwent stereotactic body radiotherapy (SBRT). 2 patients had primary tumour at rectum, 1 uterine cervix, 1 malignant thymoma and 1 from lung. Material and Methods Patients underwent 4D CT with GE 64-slice CT scanner, with respiratory motion sensor (Philips, Brilliance CT Big Bore, Netherlands), intravenous contrast were given. Internal target volume was contoured on maximum