Abstract book - ESTRO meets Asia

S120 ESTRO meets Asia 2018

Material and Methods The programs, results and performance evaluations are presented and analyzed over six-year operational period. Several parameters such as Percentage Depth Dose (PDD), Quality Index (QI), Beam Flatness and Symmetry, and Output Factor (OF) including consistency of ionization chamber factor and participation of IAEA/WHO TLD inter- comparison program. The program is designed according to the policy of the center as well as regulation imposed by Bangladesh Atomic Energy Regulatory Authority (BAERA). The chamber are calibrated on yearly basis from Secondary Standard Dosimetry Laboratory (SSDL), Bangladesh Atomic Energy Commission that traceable to the IAEA standard laboratory. Results The results of the evaluation show reproducibility in all quality assurance procedures with an average photon for monthly output factor found 0.988±0.011, 0.989±0.010 and 1.005±0.006 for 4 MV, 6 MV and 15 MV respectively. The maximum variation of calibration factors of the chambers for last six consecutive years between the manufacturer values and new calibration coefficient lies within ±0.56 to ±0.94% with an uncertainty of ±1.1% (k=1) .In the participation of postal dose inter-comparison program organized by IAEA/WHO found the deviation of stated dose to measured dose for photon beams 4 MV, 6 MV (2 beams) and 15 MV (2 beams) lies between 0.0- 3.3%with a uncertainty of±1.8% ( k=1 ). This shows in agreement set-forth by the IAEA (±5%) Conclusion The result shows an excellent agreement of calibration coefficient of ionization chamber which have a good consistency. The QA of dosimetry by inter-comparison program meets good in agreement with international standard. Under the QA program, reproducibility of all other parameters over the 24-month period for both the Linacs, as well as the accuracy and repeatability of the treatment plans generation and dose delivery were excellent. PO-291 An overview of a certified program for stereotactic radiotherapy in a Japanese general hospital M. Akimoto 1 , Y. Sonoda 2 , K. Kondo 2 , S. Itasaka 1 1 Kurashiki Central Hospital, Department of Radiation Oncology, Kurashiki, Japan 2 Kurashiki Central Hospital, Department of Radiological Technology, Kurashiki, Japan Purpose or Objective Stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) differ from conventional radiotherapy in the usage of a high radiation dose and few fractions. To ensure a treatment delivery with the highest standard of clinical practice, SRS and SBRT require sufficient equipment, specialized personnel and well- established documents. The Novalis Standard is a certified program which specifies best practice in SRS and SBRT. Our hospital is the second center that has received a certification from the Novalis Standard in Japan. We presented an overview of the Novalis Standard Certification in our hospital. Material and Methods Our hospital was established in 1923 and is contributing to health care in the community of Japan. We maintain high quality and safe medical care system with worldwide standard and are now officially accredited by Joint Commission International. The hospital has approximately 3000 staffs, including 490 physicians of 26 departments. Among these staffs, 4 oncologists, 5 medical physicists (4 of 5 are working as radiation therapists), 4 nurses, and 12 radiation therapists engage in radiation therapy. In 2017, approximately 850 new radiotherapy patients including around 70 SRS/SBRT patients were treated, and the patients are increasing. We have three machines: CLINAC

21EX, CLINAC iX, and TrueBeam STx (Varian). SRS/SBRT are provided using TrueBeam STx with Novalis Radiosurgery (BRAINLAB). Brain SRS is performed using a frameless mask system and lung or liver SBRT using a custom immobilization system. SBRT requires motion management strategies such as breath-hold, gating, and motion encompassing techniques using the RPM system (Varian) and inserted gold markers. Results The Auditors in the Novalis Standard summarized that the equipment, commissioning, machine QA and patient QA followed the guidelines and that the procedures were well documented. However, they pointed out one required action in chart review and six recommendations in staff training, the quality management program, and the QA procedures of equipment/systems. The certified program allowed improvement of staff skill specializing in SRS/SBRT and well-documentation of conference and training records in radiotherapy. Conclusion The Novalis Standard is a unique international peer review program that can assess the quality of SRS/SBRT and its safety. Our results suggest that institutions which implement SRS/SBRT would benefit from the Novalis Standard program to ensure the treatment delivery with highest standard. PO-292 Brachytherapy help reduce the dose to DARS in head and neck cancer? – A Clinical experience V. Pareek 1 , R. Bhalavat 1 , M. Chandra 1 , L. Nellore 1 , K. George 1 , D. Borade 1 , K. Kalariya 1 , N. Reddy 1 , P. Bauskar 1 , N. Kumar 1 1 Jupiter Hospital, Radiation Oncology, Mumbai, India Purpose or Objective Dysphagia/ Aspiration related structures (DARS) receiving the brachytherapy dose has been gaining importance. However, role of brachytherapy to spare these structures has not been explored yet. In this study, we evaluate role of brachytherapy in sparing DARS Material and Methods From January 2009 to Dec 2016, 35 patients with oropharyngeal cancers were evaluated, DARS structures were delineated including superior, middle and inferior constrictors and larynx. The parameters noted were structure volume, maximum dose to structure at a given point (Dmax) and total volume as a whole (MDTV) along with dose to 30%, 50% and 95% of the volume (D30, D50, D80 and D95). Toxicities assessed as per the swallowing performance status scale. Results Brachytherapy dose per fraction was 4Gy (Range 3.5 – 4.5Gy). Volume of the DARS was 23.5 cc of superior constrictor (SC), 5.6 cc of middle constrictor (MC), 3.9 cc of inferior constrictor (IC) and 29.8 cc for larynx (L). The MDTV, Dmax, D30 and D80 for SC was 65%, 118%, 78% and 66%; for MC was 61%, 70%, 63%, 60%; for IC was 55%, 59%, 57%, 55%; for L was 58%, 99%, 66%, 62%. After a median follow up of 20 months, 15% patients had Grade III status and 25% had Grade II status. Conclusion Brachytherapy has important impact, both clinically and dosimetrically to preserve DARS. In our country, application of brachytherapy as a boost or radical approach can be a better substitute for IMRT boost which is not easily available across all centers. Physics: Brachytherapy

Physics: Other

PO-293 Heterogeneity of primary and lymphoma tumors in non- small cell lung cancer based on texture of PET