First optical observation of 10B-neutron capture reactions using a boron-added liquid scintillator for quality assurance in boron neutron capture therapy

Nohtomi, Akihiro; Maeda, Hideya; Sakamoto, Naoya; Wakabayashi, Go; Takata, Takushi; Sakurai, Yoshinori

doi:10.1007/s12194-021-00645-z

Cited by 3 publications

(7 citation statements)

References 11 publications

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“…The camera system used was the same as that used in our previous paper 14 : a cooled CCD camera (SBIG-8300 M, SBIG, California, USA) with a 16-bit monochrome image sensor and an optical lens with an fnumber of 0.95 (Xenon25 F/0.95, Schneider, Germany). The camera was cooled to −5 • C during the experiment to suppress dark current noise and operated in a pixel binning mode of 5 × 5, such that the resolution of the images was 670 × 506 pixels.…”

Section: Phantom Preparation and Camera Systemmentioning

confidence: 99%

“…In contrast, in our preliminary experiments at the E-3 port of KUR, the luminescence of the 0 wt% phantom was less than 2 % of that of the 1 wt% phantom. 14 We assumed that the major origin of the present high background luminescence might be the presence of water around the phantom. Owing to 1 H(n, γ) 2 H reaction, 2.2 MeV gamma rays with a long mean free path are generated.…”

Section: Background Luminescence Of the 0 Wt% Phantommentioning

confidence: 99%

“…observation of the boron-dose distribution was successfully conducted under a neutron irradiation time of 600 s. 14 It should be noted that the neutron field characteristics of the E-3 port facility are significantly different from those of a typical accelerator based clinical BNCT facility, as summarized in Table 1. In a clinical BNCT neutron field, a short irradiation time (approximately a few seconds) is sufficient to acquire clear images because of the intensive thermal neutron flux.…”

Section: Introductionmentioning

confidence: 99%

“…We conducted a preliminary experiment using a thermal neutron beam at the E‐3 port facility of the Kyoto University Research Reactor (KUR). The first optical observation of the boron‐dose distribution was successfully conducted under a neutron irradiation time of 600 s 14 …”

Section: Introductionmentioning

confidence: 99%

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Feasibility study of optical imaging of the boron‐dose distribution by a liquid scintillator in a clinical boron neutron capture therapy field

Maeda,

Nohtomi,

et al. 2023

Medical Physics

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BackgroundEvaluation of the boron dose is essential for boron neutron capture therapy (BNCT). Nevertheless, a direct evaluation method for the boron‐dose distribution has not yet been established in the clinical BNCT field. To date, even in quality assurance (QA) measurements, the boron dose has been indirectly evaluated from the thermal neutron flux measured using the activation method with gold foil or wire and an assumed boron concentration in the QA procedure. Recently, we successfully conducted optical imaging of the boron‐dose distribution using a cooled charge‐coupled device (CCD) camera and a boron‐added liquid scintillator at the E‐3 port facility of the Kyoto University Research Reactor (KUR), which supplies an almost pure thermal neutron beam with very low gamma‐ray contamination. However, in a clinical accelerator‐based BNCT facility, there is a concern that the boron‐dose distribution may not be accurately extracted because the unwanted luminescence intensity, which is irrelevant to the boron dose is expected to increase owing to the contamination of fast neutrons and gamma rays.PurposeThe purpose of this research was to study the validity of a newly proposed method using a boron‐added liquid scintillator and a cooled CCD camera to directly observe the boron‐dose distribution in a clinical accelerator‐based BNCT field.MethodA liquid scintillator phantom with 10B was prepared by filling a small quartz glass container with a commercial liquid scintillator and boron‐containing material (trimethyl borate); its natural boron concentration was 1 wt%. Luminescence images of the boron‐neutron capture reaction were obtained in a water tank at several different depths using a CCD camera. The contribution of background luminescence, mainly due to gamma rays, was removed by subtracting the luminescence images obtained using another sole liquid scintillator phantom (natural boron concentration of 0 wt%) at each corresponding depth, and a depth profile of the boron dose with several discrete points was obtained. The obtained depth profile was compared with that of calculated boron dose, and those of thermal neutron flux which were experimentally measured or calculated using a Monte Carlo code.ResultsThe depth profile evaluated from the subtracted images indicated reasonable agreement with the calculated boron‐dose profile and thermal neutron flux profiles, except for the shallow region. This discrepancy is thought to be due to the contribution of light reflected from the tank wall. The simulation results also demonstrated that the thermal neutron flux would be severely perturbed by the 10B‐containing phantom if a relatively larger container was used to evaluate a wide range of boron‐dose distributions in a single shot. This indicates a trade‐off between the luminescence intensity of the 10B‐added phantom and its perturbation effect on the thermal neutron flux.ConclusionsAlthough a partial discrepancy was observed, the validity of the newly proposed boron‐dose evaluation method using liquid‐scintillator phantoms with and without 10B was experimentally confirmed in the neutron field of an accelerator‐based clinical BNCT facility. However, this study has some limitations, including the trade‐off problem stated above. Therefore, further studies are required to address these limitations.

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Section: Phantom Preparation and Camera Systemmentioning

confidence: 99%

Section: Background Luminescence Of the 0 Wt% Phantommentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Feasibility study of optical imaging of the boron‐dose distribution by a liquid scintillator in a clinical boron neutron capture therapy field

Maeda,

Nohtomi,

et al. 2023

Medical Physics

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“…The final-selection committee, comprising the Editor-in-Chief and seven Deputy Editors, then made the final decisions. On behalf of the Editorial Board, the Editor-in-Chief nominated three first authors of the best original papers [1][2][3]: Takayuki Okamoto for Medical Imaging, Yuma Iwao for Nuclear Medicine and Magnetic Resonance Imaging, and Akihiro Nohtomi for Radiation Therapy to the awarding societies.…”

mentioning

confidence: 99%

Announcement of nominations for the Radiological Physics and Technology awards 2022

Kanematsu

Araki

Kodera

et al. 2023

Radiol Phys Technol

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Feasibility Study of Optical Imaging of the Boron-dose Distribution by a Liquid Scintillator in a Clinical BNCT field

Maeda,

Nohtomi,

et al. 2023

2023 IEEE Nuclear Science Symposium, Medical Imaging Conference and International Symposium on Room-Temperature Semiconductor D

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First optical observation of 10B-neutron capture reactions using a boron-added liquid scintillator for quality assurance in boron neutron capture therapy

Cited by 3 publications

References 11 publications

Feasibility study of optical imaging of the boron‐dose distribution by a liquid scintillator in a clinical boron neutron capture therapy field

Feasibility study of optical imaging of the boron‐dose distribution by a liquid scintillator in a clinical boron neutron capture therapy field

Announcement of nominations for the Radiological Physics and Technology awards 2022

Feasibility Study of Optical Imaging of the Boron-dose Distribution by a Liquid Scintillator in a Clinical BNCT field

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