Abstract book - ESTRO meets Asia

S122 ESTRO meets Asia 2018

Results The average Dice coefficient of cord, brainstem, left parotid, right parotid were 0.606 ± 0.343, 0.569 ± 0.371, 0.520 ± 0.344, 0.532 ± 0.349, respectively. In spite of the low soft- contrast, soft-tissue regions could be segmented only from treatment planning CT information. Figure1 shows an example of segmentation result.

Results The conformity index average of all patients followed by standard deviation (x̄ ± s x̄ ) of the JT-IMRT, SJ-IMRT, JT- VMAT and SJ-VMAT were 1.72 ± 0.56, 1.67 ± 0.57, 1.83 ± 0.65 and 1.85 ± 0.64 and homogeneity index were 0.059 ± 0.05, 0.064 ± 0.05, 0.064 ± 0.04 and 0.064 ± 0.05. In low dose volume JT-IMRT shows a 4.69% (p-value < 0.001) overall reduction in volume receiving at least 5 Gy (V5) compare to SJ-IMRT, whereas 2.75% reduction in V5 volume in JT-VMAT compare to SJ-VMAT. JT-IMRT shows significant mean reduction in right parotid and left parotid shows of 7.64% (p-value < 0.001) and 7.45% (p-value < 0.001) compare to SJ-IMRT, while only 0.59% and 0.55% reduction were observed between JT-VMAT and SJ-VMAT. JT-IMRT plans also shows considerable dose reduction to thyroid, inferior constrictors, spinal cord and brainstem compared to the SJ-IMRT plans. Patient specific quality assurance performed using gamma evaluation method with 3 mm distance to agreement (DTA) and 3% dose difference criteria and shows a good agreement between the measured and the calculated fluence. Gamma analysis showed greater than 97% of pixels were passed for all the plans and this shows the difference between dose calculation and measurements are within the tolerance. Conclusion Jaw tracking resulted in decreased dose to critical structures in IMRT and VMAT plans. But significant dose reductions were observed for critical structure in the JT- IMRT compared to SJ-IMRT technique. In JT-VMAT plans dose reduction to the critical structure were not significant compared to the SJ-IMRT due to relatively lesser monitor units. PO-297 Enhancement of radio sensitization by gold-silica shell- core NPs in MCF7 breast cancer cells G. Darfarin 1 , S. Roya 1,2 , A. Effat 3 , N.M. Behnam 4 , A. Abolfazl 5,6 , F. Ali Reza 1,7,8 1 Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran Islamic Republic of 2 Department of Medical Nanotechnology- Faculty of Adva nced Medical Sciences-, Tabriz University of Medical Science, Tabriz, Iran Islamic Republic of 3 Department of Medical Biotechnology- Faculty of Advan ced Medical Science-, Tabriz University of Medical Sciences, Tabriz, Iran Islamic Republic of 4 Department of Radiation Oncology, Tabriz Valiasr Hospital, Tabriz, Iran Islamic Republic of 5 Tuberculosis and Lung Disease Research Center of Tabri z-, Tabriz University of Medical Sciences, Tabriz, Iran Islamic Republic of 6 Department of Chemical Engineering, North- eastern University, Boston, USA 7 Imam Reza University Hospital- Radiotherapy Departme nt, Tabriz University of Medical sciences, Tabriz, Iran Islamic Republic of 8 Department of Medical Physic- Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran Islamic Republic of Purpose or Objective This study aimed to take advantage of gold-silicon oxide shell-core nanoparticle to evaluate radiation dose enhancement effect in megavoltage radiotherapy of MCF7 cells. Material and Methods In this work gold-silicon oxide shell-core nanoparticles (NPs) were synthesized by conjugation of gold nanoparticle with amine or thiol functionalized silica nanoparticles (AuN@SiO2 and AuS@SiO2). The prepared nanoparticle was characterized by FTIR and TEM. The NPs treated cells were irradiated by using 6 and 18 MV x-rays.

Figure 1 Segmentation result. This figure shows a part of CT image, ground truth and predict image. Conclusion Our preliminary results showed a feasibility of automatic segmentation using DCNN in head and neck cancer radiotherapy. PO-296 Influence of Jaw tracking in IMRT and VMAT radiotherapy for Head and Neck Cancers: A Dosimetric Study S. Ahmed 1 , K. Raj Mani 2 , R.U. Nabi 2 , M.A. Bhuiyan 2 , H. Khondokar Anamul 2 , S. Ashim kumar 2 1 United Hospital Ltd., Oncology, Dhaka, Bangladesh 2 United Hospital Ltd., Oncology, Dhaka, Bangladesh Purpose or Objective To Study the dosimetric advantage of the Jaw tracking technique in Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) for Head and Neck Cancers. Material and Methods We retrospectively selected ten previously treated head and neck cancer patients stage (T1/T2, N1, M0) in this study. All the patients were planned for IMRT and VMAT with simultaneous integrated boost (SIB) technique to deliver a differential dose per fraction to the high, intermediate and low risk volume using a single plan. We intend to deliver 70 Gy to the high-risk volume, 64 Gy to the intermediate risk volume and 56 Gy to the low risk volumes in 35 fractions. All the plans were planned with 6MV photons using Millennium 120 MLC. IMRT and VMAT plans were performed with jaw tracking (JT) and with static jaw (SJ) technique by keeping the same constraints and priorities for the target volumes and critical structures for a particular patient. Plans were normalized at the target mean of the high-risk volumes. All the plans were accepted with the criteria of parotid glands mean dose < 25 Gy and spinal cord maximum point dose < 45 Gy without compromising the target volumes. Target conformity, dose to the critical structures and low dose volumes were recorded and analyzed for IMRT and VMAT plans with and without jaw tracking for all the patients.