Abstract book - ESTRO meets Asia

S87 ESTRO meets Asia 2018

the superior border of the PBT. Contour variations may be large enough to influence clinicians’ assessment of tumour centrality; i.e. patients’ eligibility for SABR treatments. Interventions to reduce observer variations in contouring the PBT, such as clear consensus guidelines and/or reliable automated methods, are highly recommended to ensure more consistent assessment of tumour centrality. PO-213 Stereotactic body radiotherapy using a real-time tumor tracking system and fiducial markers. Y. Hiroshima 1 , Y. Tamaki 1 , T. Saitoh 1 , T. Ohno 2 , K. Shinoda 1 , K. Nitta 1 1 Ibaraki Prefectural Central Hospital, Radiation Oncology, Kasama, Japan 2 Dokkyo Medical University, Radiology, Koshigaya, Japan Purpose or Objective A fluoroscopic real-time tumor tracking system SyncTraX FX4 (Shimadzu Co. Kyoto, Japan) enables that transmits an irradiation permission signal to a treatment device while a fiducial marker is within a target position, and stops transmission when it comes off. Using this system, we can reduce the irradiation volume of normal tissue while guaranteeing the positional accuracy of the tumor even under free breathing, and improve the patients’ burden and adverse events. We report the safety and the feasibility of the stereotactic radiotherapy using this system. Material and Methods A total of 6 patients and 7 sites treated in our institute between October 2017 and April 2018 were retrospectively reviewed. This study included 5 men and 1 woman, whose age ranged from 66 to 83 years (median 71 years). Treated organs were lung: liver was 3: 3, and 3 primary tumors and 3 metastatic tumors each. Fiducial markers were inserted before the treatment planning CT scan; namely Visicoil (SCETI MEDICAL LAB, Tokyo, Japan) to the liver and Disposable Gold Marker (Olympus Co. Tokyo, Japan) to the lung. TrueBeam STX was used as the treatment device, and irradiation method was fixed multiple irradiation, 3DCRT. Prescribed dose was 55.0 Gy/ 4 fr or 66.0 Gy/ 10 fr (D 95 prescription), planned with Raystation. Results Tumor volume and PTV volume were ranged 4.29 cc – 45.37 cc (median 16.32cc), and 9.82 cc- 87.44 cc (median 31.84 cc), respectively. The conformity index (CI) in each irradiation field was 0.82 - 0.9, and the median value of CI was 0.85. Follow-up period was 0.8 - 6.1 (median 1.2 ) months, and no serious adverse events related to radiotherapy and inserting fiducial markers were observed during the period. Although a treatment was based on free breathing, it was able to shorten patient radiation exposure and treatment time by using in combination with respiratory holding system. In the liver, because of difficulty to follow fiducial markers depending on the perspective direction, there was a case which needed a change of treatment plan.

Conclusion Stereotactic body radiotherapy using a real-time tumor tracking system and fiducial markers was a safe and less burdensome treatment. PO-214 “Liquid Withdarw” technique prominently improved the feasibility of CT-guided lung biopsy. R. Li 1 , W. Lifeng 1 , W. Ren 1 , P. Jiang 1 , Y. Yan 1 , Z. Xia 1 , R. Jiang 1 , B. Liu 1 1 Drum Tower Hospital Affiliated to Medical School of Na njing University, The Comprehensive Cancer Center, Nanjing, China Purpose or Objective CT-guided cutting needle lung biopsy is important for the diagnosis of lung cancer. It has become more and more important with the development of SBRT as a curative option for early stage NSCLC. The co-axial method is now widely used in CT-guided lung biopsy. However, co-axial method failed to decrease the incidence of pneumothorax. In this reported, we retrospectively studied 90 patients undergoing CT-guided cutting needle lung biopsy to investigate the role of this technique in reducing complications and promoting biopsy effevtiveness.

Material and Methods From Jan 1 st , 2014 to Nov 30 th , 2016, we retrospectively studied 92 CT-guided percutaneous lung biopsy using co- axial and liquid withdraw techniques in 90 patients. During the biopsy procedure, a 19-gauge guiding needle was inserted into the lesion over the inducer needle. Then, multiple specimens (mostly 4-6) were obtained with an 18- gauge biopsy gun. The pathologies (cytology, histology and EGFR mutation status) and complications secondary to biopsy procedure (pneumothorax and bleeding) were noted. Pneumothorax and bleeding was graded as mild (mild and very mild), moderate, and severe. Results 88 cases was diagnosed out of 92 biopsies (95.7%), of which 60 cases were adenocarcinoma (52 patients consented EGFR mutation test, and 36 cases had EGFR