Browsing by Author "Hamato, A"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    P219 / #908 - advancements in NCEPT: animal study outcomes and technological developments toward clinical application
    (Elsevier, 2024-06) Hirayama, R; Tashima, H; Hamato, A; Howell, NR; Sierro, F; Kielly, M; Caracciolo, A; Franklin, DR; Guatelli, S; Yamaya, T; Rosenfeld, AB; Fiorini, C; Carminati, M; Safavi-Naeini, M
    Background and aims: Neutron Capture Enhanced Particle Therapy (NCEPT) represents a promising advancement in cancer treatment, utilising neutron capture agents (NCAs) to enhance therapeutic efficacy of proton/heavy ion radiation. This work focuses on animal experiments and concurrent technological developments aimed at translating NCEPT into clinical practice. Methods: Animal studies were conducted to assess the therapeutic impact of NCEPT. Baseline dose response of U87MG xenograft Balb/c nu/nu mice to 12C and 4He ion radiation was evaluated at HIMAC (February 2021, January 2022). NCEPT dose-response experiments with 10B-BPA as the NCA and using the same animal model were conducted in two campaigns in 2023. 200 mice were irradiated with helium or carbon ions across four dose levels (0 Gy, 5 Gy, 10 Gy, and 15 Gy, n = 6 mice/ion/dose); tumour growth was measured at different time points. In parallel, a scintillator-based detector for measurement of photon spectrum changes due to neutron capture was developed and evaluated in simulations and experiments with boron-loaded PMMA targets irradiated by helium/carbon ion beams. Results: Baseline experiments showed expected dose-response relationships, with tumour response and measured neutron fluence informing the NCEPT study protocol. NCEPT experiments demonstrated significant tumour volume reductions (33%/46% for helium/carbon ion irradiation, respectively) and delays in tumour growth relative to baseline. The prototype detector measured increases in the area of the 478 keV peak by 26%/45% for helium/carbon beams, respectively, compared to simulation-based values of 57%/45%. >65% of these photons originated from 10B captures in the detector's PCB, highlighting the need for neutron shielding and boron-free materials in detector construction. The linear increase in neutron capture photons at 10B concentrations up to 20000 ppm, with potential for detection down to 100 ppm using temporal windowing, paves the way for a SPECT-like neutron capture imaging system, crucial for NCEPT quality assurance. Conclusion: The combined animal study outcomes and technological advancements underscore the potential of NCEPT as a highly effective cancer therapy. The progress in dosimetry and imaging techniques mark significant steps toward the clinical translation of NCEPT, promising improved patient outcomes in cancer treatment. © 2024 Elsevier B.V. Open Access under a CC-BY-NC-ND 4.0 licence
  • Thumbnail Image
    Item
    A quantitative assessment of Geant4 for predicting the yield and distribution of positron-emitting fragments in ion beam therapy
    (IOP Publishing, 2024-06-21) Chacon, A; Rutherford, H; Hamato, A; Nitta, M; Nishikido, F; Iwao, Y; Tashima, H; Yoshida, E; Akamatsu, G; Takyu, S; Kang, HG; Franklin, DR; Parodi, K; Yamaya, T; Rosenfeld, AB; Guatelli, S; Safavi-Naeini, M
    Objective. To compare the accuracy with which different hadronic inelastic physics models across ten Geant4 Monte Carlo simulation toolkit versions can predict positron-emitting fragments produced along the beam path during carbon and oxygen ion therapy. Approach. Phantoms of polyethylene, gelatin, or poly(methyl methacrylate) were irradiated with monoenergetic carbon and oxygen ion beams. Post-irradiation, 4D PET images were acquired and parent 11C, 10C and 15O radionuclides contributions in each voxel were determined from the extracted time activity curves. Next, the experimental configurations were simulated in Geant4 Monte Carlo versions 10.0 to 11.1, with three different fragmentation models—binary ion cascade (BIC), quantum molecular dynamics (QMD) and the Liege intranuclear cascade (INCL++) - 30 model-version combinations. Total positron annihilation and parent isotope production yields predicted by each simulation were compared between simulations and experiments using normalised mean squared error and Pearson cross-correlation coefficient. Finally, we compared the depth of the maximum positron annihilation yield and the distal point at which the positron yield decreases to 50% of peak between each model and the experimental results. Main results. Performance varied considerably across versions and models, with no one version/model combination providing the best prediction of all positron-emitting fragments in all evaluated target materials and irradiation conditions. BIC in Geant4 10.2 provided the best overall agreement with experimental results in the largest number of test cases. QMD consistently provided the best estimates of both the depth of peak positron yield (10.4 and 10.6) and the distal 50%-of-peak point (10.2), while BIC also performed well and INCL generally performed the worst across most Geant4 versions. Significance. The best predictions of the spatial distribution of positron annihilations and positron-emitting fragment production along the beam path during carbon and oxygen ion therapy was obtained using Geant4 10.2.p03 with BIC or QMD. These version/model combinations are recommended for future heavy ion therapy research. © 2024 The Author(s). Published on behalf of Institute of Physics and Engineering in Medicine by IOP Publishing Ltd - Open Access - Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.