Abstract
AB013. Image reconstruction with limited-view-angle projection data for boron neutron capture therapy-single-photon emission computed tomography—establishment of the mock-up system and validation of the response function
Fan Lu, Kouki Okuda, Haruka Inamoto, Shingo Tamaki, Sachie Kusaka, Isao Murata
Division of Sustainable Energy and Environmental Engineering, Department of Engineering, Graduate School of Engineering, Osaka University, Osaka, Japan
Correspondence to: Isao Murata, PhD. Division of Sustainable Energy and Environmental Engineering, Department of Engineering, Graduate School of Engineering, Osaka University, Yamada-oka 2-1, Suita, Osaka 565-0871, Japan. Email: murata@see.eng.osaka-u.ac.jp.
Background: Boron neutron capture therapy (BNCT) is expected to be a new radiation therapy, and research on various issues is still in progress. One of the unsolved issues is the development of a new system to measure the treatment effect of BNCT in real-time, and there are high expectations for a method to measure gamma-rays emitted promptly via boron-neutron capture reaction from outside of a human body and to reconstruct the images in a single-photon emission computed tomography (SPECT)-like manner (BNCT-SPECT). The objective of the present study is to develop a new mock-up system so as to reproduce the accuracy of the real BNCT-SPECT for validation of the response function.
Methods: In a typical SPECT system, in which the projection angle range of the detector array is up to about 360 degrees at most. Nevertheless, in BNCT-SPECT, we must set up the patient’s body on the surface of the neutron exit wall, and the angle available for the radiation measurement is limited to less than 180 degrees. Therefore, Fourier image reconstruction methods that require projections from at least 180-degree directions cannot be applied to BNCT-SPECT. To solve this problem, we are trying to develop a new successive approximation image reconstruction method based on Bayesian estimation, which is valid even under severe conditions specific to BNCT-SPECT and finally demonstrates the BNCT-SPECT. In this study, we perform mock-up experiments and MCNP (a general Monte Carlo N-particle transport code) simulations to obtain limited-view-angle projection data and the response function with which we can reconstruct images successfully.
Results: We have been developing the image reconstruction method with Bayesian estimation to solve the problem that artifact is seen in the reconstructed images compared with the true images. We constructed a mock-up system to investigate the experimental specifications for the BNCT-SPECT system development, in order to validate the response function of the measurement system of the BNCT-SPECT evaluated by MCNP5. However, the mock-up system cannot reproduce the actual accuracy of a real BNCT-SPECT system because the source intensity in the mock-up experiment is too weak compared to the real one, if we measure with designed detectors shooting from the moving angle we decided. So, we had to establish the experimental system that has the same statistical accuracy and signal-to-noise ratio as the real BNCT-SPECT system. For this purpose, the mock-up system was modified by setting and changing a gamma-ray source to adjust the background intensity so as to reproduce the actual accuracy of the designed BNCT-SPECT.
Conclusions: We have established an experimental mock-up system that can reproduce the actual accuracy and the response function was verified with the mock-up system. We then finally develop a reliable image reconstruction system for BNCT-SPECT.
Keywords: Boron neutron capture therapy-single-photon emission computed tomography (BNCT-SPECT); image reconstruction; limited-view-angle projection; mock-up system; response function
Acknowledgments
None.
Funding: None.
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tro.amegroups.com/article/view/10.21037/tro-25-ab013/coif). The authors have no conflicts of interest to declare.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Ethical approval was not required for this study because it did not involve human or animal participants, nor did it entail the use of personal data.
Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the noncommercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.
doi: 10.21037/tro-25-ab013
Cite this abstract as: Lu F, Okuda K, Inamoto H, Tamaki S, Kusaka S, Murata I. AB013. Image reconstruction with limited-view-angle projection data for boron neutron capture therapy-single-photon emission computed tomography—establishment of the mock-up system and validation of the response function. Ther Radiol Oncol 2025;9:AB013.
