First measured optical image of Cerenkov-light in water during irradiation of neutron beam from boron neutron capture therapy (BNCT) system

Yabe, Takuya; Yamamoto, Seiichi; Hu, Naonori; Kanai, Yasukazu; Tanaka, Hiroki; Ono, Koji

doi:10.1016/j.radmeas.2021.106633

Cited by 3 publications

(4 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Section: Discussionsupporting

confidence: 53%

“…One possible reason for this discrepancy is the contribution of the water luminescence, as shown in Figure 10. This luminescence is thought to be due to Cerenkov light as reported by Yabe et al 13 Figure 11 illustrates that approximately 30 % of the total pixel values of the 0 wt% phantom observed around the three peaks may be due to the contribution of Cerenkov light generated in the surrounding water. Usually, Cerenkov light is far weaker than the scintillation light; however, it can be detected as a certain signal because the volume of water irradiated with neutrons is larger than that of the scintillator,as previously mentioned.…”

Section: Background Luminescence Of the 0 Wt% Phantommentioning

confidence: 99%

“…[9][10][11] Recently, in a clinical BNCT facility, Yamamoto et al and Yabe et al reported the optical imaging of thermal neutron distribution and Cerenkov radiation distribution, which originated from 2.2 MeV gamma rays owing to the 1 H(n, γ) 2 H reaction. 12,13 Motivated by these previous studies, we attempted direct optical observation of the boron-dose distribution using a 10 B-added liquid scintillator and a charge-coupled device (CCD) camera. We conducted a preliminary experiment using a thermal neutron beam at the E-3 port facility of the Kyoto University Research Reactor (KUR).…”

Section: Introductionmentioning

confidence: 99%

“…and Yabe et al. reported the optical imaging of thermal neutron distribution and Cerenkov radiation distribution, which originated from 2.2 MeV gamma rays owing to the 1 H(n, γ) 2 H reaction 12,13 . Motivated by these previous studies, we attempted direct optical observation of the boron‐dose distribution using a 10 B‐added liquid scintillator and a charge‐coupled device (CCD) camera.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionsupporting

confidence: 53%

Section: Background Luminescence Of the 0 Wt% Phantommentioning

confidence: 99%