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Dosimetric Impact of Intratreatment Displacement in Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT) for the High-Grade Glioma

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T Kato

T Kato*, K Hirose , T Harada , K Arai , T Motoyanagi , R Shimokomaki , Y Takai , Southern Tohoku BNCT Research Center, Koriyama, Fukushima


SU-I-GPD-T-208 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To evaluate the dosimetric impact of intratreatment displacement quantitatively in accelerator-based boron neutron capture therapy (AB-BNCT) for the high-grade glioma using Simulation Environment for Radiotherapy Applications (SERA), a currently available BNCT treatment planning.

Methods: Newly installed AB-BNCT system (Sumitomo Heavy Industries, Ltd.) was used in this study. 3 patients with the high-grade glioma on their temporal or parietal lobe were selected. First, based on Gd contrast-enhanced T1-weighted imaging, tumor (GTV) and organs at risk were delineated, next, based on FLAIR-weighted imaging, the area of high signal intensity on FLAIR (FLAIR-high area) was delineated. After calculations using SERA, the maximum, minimum, and mean doses for the GTV and the FLAIR-high area were evaluated. To clarify the impact of intratreatment displacement for the doses of the GTV and the FLAIR-high area, simulations were performed in conditions that the irradiation fields shifted 2, 5 and 10 mm to the directions of RL, AP and SI in each respective patient.

Results: For the deviation of irradiation field in the directions of RL and SI, the maximum, minimum and mean doses for the GTV and the FLAIR-high area tended to become lower than that in original plan. A maximum dose reduction of over 25 % in GTV minimum dose was noticed for 10 mm shifted to the RL and SI directions. One of 3 patients had unacceptable coverage as defined dose reduction within 10 % compared with the original plan for 5 mm shifted to the RL and SI directions.

Conclusion: Intratreatment displacement had a significant impact on the dose for the target, so translational positioning error was needed to be maintained below 5 mm even in BNCT. Pretreatment evaluation for the degree of deviation that can compensate therapeutically effective dose should be performed in each patient treatment.

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