ESTRO 36 Abstract Book

S950 ESTRO 36 2017 _______________________________________________________________________________________________

for cancer patients worldwide. This program is administered through five RT and DI core support services: site qualification, trial design support/assistance, credentialing, pre- and post-case review data management, and case review. IROC also provides educational efforts to improve the understanding of the protocols by participating institutions. IROC monitors over 2000 participating institutions that include nearly 100 participating institutions outside of North America. Results IROC currently provides core support for 172 NCTN trials with RT, DI and RT/DI components. Many of these trials were legacy trial from the previous cooperative group program. IROC monitors nearly 1800 RT photon and 20 proton institutions. Over 28,000 beams outputs were monitored with 8% of the sites requiring repeat audits due to beam out of criteria. As part of credentialing, 950 QA phantoms have been irradiated, 515 imaging modalities evaluated and almost 4000 credentialing letters have been issued. In just year 2, 5290 RT and 4934 DI patient datasets were received (many using TRIAD) by IROC QA Centers to be prepared for review. During the past 2 years, a total of 6300 RT cases and 19,000 DI image sets were reviewed by IROC technical staff. To date, IROC has published 36 manuscripts. Conclusion The QA services provided by IROC are numerous and are continually being evaluated for effectiveness, harmonized across all NCTN Groups and administered in an efficient and timely manner to enhance accurate and per protocol trial data submission. These efforts increase each NCTN Group’s ability to derive meaningful outcomes from their clinical trials. EP-1750 Enhanced radiotherapy by novel class of radiosensitizers based Bismuth and Gadolinium nanoparticles S. Farahani 1 , N. Riyahi alam 1 , E. Gorji 2 , R. Rahnamafar 3 , S. Fazli 4 , H. Khosravi 5 , M. Pakravan 1 , V. Shahabian 6 , S. Haghgoo 2 1 Tehran University of Medical Sciences Radiation On, Department of Medical Physics, Tehran, Iran Islamic Republic of 2 Food & Drug Organization, Pharmaceutical Department- Food & Drug Laboratory Research Center, Tehran, Iran Islamic Republic of 3 Kashan University, Chemistry Department- Faculty of Sciences, Kashan, Iran Islamic Republic of 4 Science and Research Branch- Islamic Azad University, Nuclear Engineering Department, Tehran, Iran Islamic Republic of 5 Tarbiat Modares University, Department of Medical Physics, Tehran, Iran Islamic Republic of 6 Tehran University of Medical Sciences Radiation On, Sina Specialized and subspecialty Hospital, Tehran, Iran Islamic Republic of Purpose or Objective Recently, the use of nanoparticles with a high atomic number as a new class of radiation sensitizers, to increase the tumor dose and sparing normal tissues has become a hot topic in radiotherapy treatments. Meanwhile, Bismuth and Gadolinium based nanoparticles, can not only be used in CT and MRI as contrast agents, but also can be feasible radiosensitizers in radiotherapy. Hence they are attractive candidates for multimodal dose enhancement studies. In this study, the ability of dose enhancement of these nanoparticles using MAGIC-f polymer gel under the internal Iridium-192 and the external Cobalt-60 radiotherapy practices were investigated. Material and Methods The Bi2O3-NPs less than 40 nm in diameter and 0.1 mM concentration were synthesized. To increase the precision of the gel dosimetry a Plexiglas phantom was designed and made, all of the gel filled vials (with and without the

nanoparticles) were irradiated to an Ir-192 radioactive source simultaneously. Also, Irradiation was carried out with a Co-60 teletherapy unit. Results The maximum dose enhancement factors under the internal Iridium-192 radiotherapy were 31% and 22% in the presence of Bi2O3-NPs and Gd2O3-NPs, respectively, whereas these amounts were reduced to 1% in external radiotherapy by Co-60 photons. Conclusion The results of our research approves the use of Bismuth and Gadolinium based nanoparticles in brachytherapy. Additionally, the polymer gel dosimetry can be a feasible material for verification and estimation of dose enhancements in the presence of nanoparticles. EP-1751 A comparison of tools for Delivery Quality Assurance in TomoTherapy T. Santos 1 , T. Ventura 2 , J. Mateus 2 , M. Capela 2 , M.D.C. Lopes 2 1 Faculty of Sciences and Technology, Physics Department, Coimbra, Portugal 2 IPOCFG- E.P.E., Medical Physics Department, Coimbra, Portugal Purpose or Objective A TomoTherapy HD unit has recently been installed in our hospital. The purpose of the present work is to establish an accurate and efficient method of patient specific delivery quality assurance (DQA). Four available tools (EBT3 Grafchromic film, Dosimetry Check –DC –, ArcCHECK TM and RadCalc®) have been tested and compared. Material and Methods Standard patient plan verification in TomoTherapy is done through film dosimetry in the Cheese Virtual Water TM phantom. Also point dose measurements can be performed inserting ionization chambers in this phantom. A well- established film absolute dosimetry methodology using EBT3 Gafchromic film and applying a multichannel correction method was developed in-house, adapting the standard approach in the DQA Tomo station. The treatment plans of the first 21 patients were retrospectively verified using also Dosimetry Check software (Math Resolutions, LLC) and ArcCHECK TM (Sun Nuclear). A beta version of RadCalc®6.3 (LifeLine Software Inc.) for TomoTherapy has been used for independent treatment time calculation. DC uses the MVCT detector sinogram to reconstruct the 3D dose distribution. In this work it was used in pre-treatment mode with the couch out of the bore. The transit dose mode where the patient delivered dose reconstruction is obtained was not assessed in this work. ArcCHECK TM records the signal of 1386 diodes embedded as a helical grid on a cylindrical phantom, enabling 4D volumetric measurements. The Gamma passing rate acceptance limit was 95% using a 3%/3 mm criterion in all cases. Results All the used QA tools showed a good agreement between measured and planned doses. Film and DC achieved similar results with mean Gamma passing rates of 98.8±1.6% (1SD) for EBT3 film and 97.9±1.6% (1SD) for DC. Moreover, a correlation was found between those results: when passing rates using film were poorer (<97%), the same happened with DC, while passing rates over 97% for DC corresponded to the same range using film. This correspondence was not verified with ArcCHECK TM where Gamma passing rates were always close to 100% (99.6±0.7% (1SD)). Concerning the independent treatment time verification with Radcalc®, the percentage difference to the Tomo TPS calculation was 0.2±2.5% (1SD), on average. Conclusion