CO6-1

Design and Synthesis of Boron-containing Compounds for Effective Accumulaionin Tumor Tissues and Detection by Boron Magnetic Resonance Imaging

S. Aoki1, T. Tanaka1, Y. Hisamatsu1, Y. Sawamoto1, Rikita
Araki2, Takaomi Saido3, T. Suzuki4, K. Horie4, Ryo Abe4,
S. Masunaga5, N. Kondo5, Y. Sakurai5, and K. Ono5
1

Faculty of Pharmaceutical Sciences, Tokyo University of
Science2
Bruker Biospin K. K.
3

RIKEN Brain Science Institute4

Research Institute of Biomedical Sciences, Tokyo University of Science
5
Research Reactor Institute, Kyoto University
INTRODUCTION: Boron neutron capture therapy(BNCT) is one of powerful therapies for local tumor control in the treatment of brain tumor, melanoma, and so on[1]. Our object in this work is to develop new methods
for the tumor-specific accumulation of boron-containing
compounds and the real-time detection of B concentrations in local tumor tissues. In this study, we have designed and synthesized new boron compounds appended
with glucose moiety and metal chelators for BNCT and B
NMR (nuclear magnetic resonance) or MRI (magnetic
resonance imaging) [2].

Fig 1. Deboronation reaction of carborane derivatives 1
and 2, induced by Cu(II) in aqueous solutions.
EXPERIMENTS and RESULTS:
B NMR and MRI change of carborane derivatives
by decomposition reaction promoted by copper(II).
Decomposition reaction of 1 and 2 was by 11B NMR
and MRI. Interestingly, the probe 2 undergoes fasterdecomposition than that of 1 at 37 oC and neutral pH,
which was successfully detected on 11B NMR and MRI[3,4].
1128004

Concice and versatile synthesis of natural productderivatives that possess B-cluster parts
Sulfoquinovosyl acylpropanediol (SQAP) has beenreported to show a variety of biological activities, including accumulation in tumor cells and the inhibitionof tumor cell growth. We developed a new concise
and versatile synthesis of SQAP itself and derivatives
bearing iodoaryl groups and boronclusters (5) startingfrom compound 3 via the selective acylation at C1
position of the intermediate 4 [5].

Fig 2. The synthetic route for preparing SQAP derivatives in this study
Design and synthesis of new carriers of boron-containing compounds.
The aforementioned results prompted us to designand synthesize new carrier compounds of B-containing
compounds. It was found that uptake of the conjugate
compounds of our new carriers and B-containing compounds is almost similar to boronylphenylalanine (BPA)(these structures are not shown in this paper, because they
will be submitted to the patent in due course).
.
REFERENCES:[1] a) R. F. Barth et al., Clin. Cancer Res., 11 (2005)
3987-4002. b) R. F. Barth et al. Rad. Oncol. 7 (2012)
146-166.
[2] a) G. W. Kalbalka, et al. J. Neuro-Oncol. 33 (1997)
153-161. b) P. Bendel, NMR in Biomed. 18 (2005) 74-82.
[3] T. Tanaka et al., Eur. J. Inorg. Chem. 1819-1834(2016).
[4] T. Tanaka et al., Eur. J. Inorg. Chem. 3330-3337(2016).
[5] T. Tanaka et al., Chem. Pharm. Bull. 65, 566-572(2017).

CO6-2

Study of Localization Estimation of Abasic Sites in
DNA Irradiated with Ionizing Radiation

K. Akamatsu, N. Shikazono and T. Saito1
Irreparable DNA Damage Analysis Research Group,
Quantum Beam Science Research Center, Japan Atomic
Energy Agency (JAEA)
1
Research Reactor Institute, Kyoto University
INTRODUCTION:
DNA lesions induced by ionizing radiation andchemicals can cause mutation and carcinogenesis. In
particular, “clustered damage” site, that is a DNA region
with multiple lesions within one or two helical turns, isbelieved to hardly be repaired. This damage is considered
to be induced, e.g., around high-LET ionizing radiation
tracks. However, detail of the damage is not known. We
have already developed a method for estimating degreeof localization of abasic sites (APs) in DNA using Förster
resonance energy transfer occurred between different
fluorescence probes (“hetero-FRET” using Alexa350 andAlexa488) [1] . The results showed that 12C5+ beam produced close APs within a track: the apparent distancecalculated was approximately 17 base pairs [2]. Thisfinding indicates that direct radiation effect of 12C5+ beamnear the Bragg peak produces clustered DNA damage.
We have recently applied the method to DNA in acell-mimetic radical scavenging condition. However,there are some problems of the complex protocol and of
the sensitivity due to the low extinction coefficient of
Alexa350. We have, therefore, developed “homo-FRET”
occurred between two or more Alexa488 molecules. We
will obtain magnitude of FRET also from “fluorescenceanisotropy” of homo-FRET between Alexa488 molecules.
The new protocol using homo-FRET enables us to estimate DNA damage localization without any enzymes andimproves sensitivity to detect a clustered damage.
EXPERIMENTS:●Sample preparation and irradiation
The plasmid DNA digested by Sma I was used (linear
form). The DNA was dissolved to be 0.1 g/L in 0.2 M
Tris-HCl buffer (pH 7.5) which is a cell-mimetic condition in relation to radical scavenging capacity. Twenty
microliters of the DNA solution was transferred to a microtube (0.5-mL size), and was irradiated with 60Co
-rays (LET: ~0.2 keV/m; Kyoto University Research
Reactor Institute: KURRI) as a standard radiation source.
Moreover, the DNA solution was irradiated with carbon
ion beam (LET: ~ 90 keV/m) at HIMAC (National Institute of Radiological Sciences, QST).
●Preparation of fluorophore-labeled irradiated DNA andthe FRET observation
The irradiated DNA (10 L in water) and 10 L of
100 mM Tris-HCl (pH 7.5) were mixed in a microtube.
Two microliters of Alexa488/DMSO was added to the
DNA solution and was incubated for 24 h at 35°C. The
fluorophore-labeled DNA was purified by ethanol-precipitation followed by ultrafiltration. The fluores-

28019

cence anisotropy was measured at 525 nm (ex. 470 nm).
The anisotropy, < r >, is defined as follows:r 

IVV  G IVH ,IVV  2G IVH

where IVV is the fluorescence intensity when the excitation and emission polarizers are both vertically oriented.
IVH is one when the excitation/emission polarizers arevertically/horizontally oriented. G is the grating factor
defined as IHV/IHH.
RESULTS AND DISCUSSION:

Fig. 1. Relationship between AP average density (the numberof APs per kilo base pairs) and fluorescence anisotropy for 60Co
-rays () and carbon ion beam (HIMAC) (●).

In general, fluorescence anisotropy decreases withincreasing FRET [3]. As shown in Fig.1, there was a little difference between the -ray data points and a theoretical curve based on exponential distribution. Thisfinding suggest that APs produced by the -rays arelikely to be localized compared to those randomly distributed. This tendency is similar to the hetero-FRET
results as shown previously [2]. A radiation “spur” on or
nearby DNA might sometimes produces clustereddamage. On the other hand, the anisotropy curve(points) for carbon ion beam was slightly lower thanthat for the -rays, whereas that for carbon ion beam to
dry DNA was much lower than these experiment toaqueous DNA (data not shown). This implies that clustered DNA damage mainly occurs by direct radiation
effect.
REFERENCES:[1] K. Akamatsu, N. Shikazono, Anal. Biochem. 433(2013) 171-180.
[2] K. Akamatsu, N. Shikazono, and T. Saito, Radiat.
Res. 183 (2015) 105-113.
[3] L. W. Runnels, and S. F. Scarlata, Biophys. J. 69(1995) 1569.

CO6-3Age-related Stresses Induce Asp Isomerizations of αA-crystallin in Lens

T. Takata1,2 and N. Fujii2
1

Tokyo University of Pharmacy and Life Sciences2
Research Reactor Institute, Kyoto University

INTRODUCTION: The passive chaperone lens
α-crystallin (α-Crys), a small heat shock protein, is composed of two subunits (~ 20 kDa) αA- and αB-crystallin(αA-Crys and αB-Crys), which form a hetero-oligomericand polydisperse complex with molecular mass of ~ 600
kDa in the vertebrate lenses. Recent studies by
LC/MS/MS analysis have shown that many aspartyl residues (Asp) in αA-Crys inverted to isomers (Lβ-Asp,
Dα-Asp, Dβ-Asp) with age (1-2). However, it is not wellunderstood whether Asp isomers in native polymeric
αA-Crys are different from those in dissociated αA-Crys.
In the present study, we examined to clarify the isomerized Asp in dissociated αA-Crys, which may contributeto abnormal lens protein subunit-subunit interactions inaged lens.
EXPERIMENTS: Lens of four different ages (42, 54,
69 and 83 years old) were homogenized, centrifuged, andthe soluble fraction was applied to size-exclusion chromatography (Fig. 1). The polymeric and monomeric
αA-Crys fractions were independently obtained, and thendigested by trypsin. Each tryptic peptide was applied tomass spectrometry equipped with nano-scale liquid
chromatography to extract each of αA-Crys-derived peptides containing Asp isomers. The ratio of Asp isomers
was determined by the comparison of peak area from four
Asp isomer containing peptide.

RESULTS: αA-Crys was identified as a polymeric andmonomeric state in the soluble fraction of aged lens. The
isomerization of Asp 58, Asp 84 and Asp 151 of αA-Crys
were highly detectable in the monomeric fraction, but not
those in the polymeric one. These results showed that the
distribution of Asp isomers is different between the dissociated and aggregated states of α-Crys in aged lens.
Furthermore, The ratios of Asp isomers at the residues,
58, 84 and 151 in monomeric αA-crystallin were
age-dependent and similar to the previously reported ratio
in αA-crystallin from the water-insoluble fraction of agedlens (Fig. 2). Thereby, age-dependent Asp isomerizationin α-Crys is likely to contribute to the solubility of lensprotein in aged lens. Age-dependent isomerization of Asp
is also stress dependent. The more damage in lens, themore isomerization would be presented in lens Crys evenin the same age. In future study, we will add various
stresses into lens Crys such as UV, γ-ray and neutron
beam to cause oxidative damage, and quantitated isomerization. From current study, our conclusion is that theisomerization of Asp as well as many other modifications
would reduce the normal subunit-subunit interaction of
α-Crys with aging, resulting in senile cataract formation.

Fig. 2. Age-dependent isomerization of Asp 58 in
αAT6 from the monomeric crystallin fraction.
The isolated monomeric fraction was further digested by trypsin and applied for LC-MS/MS
analysis. Top panel; 42-year-old lens monomeric
crystallin fractions. Bottom panel; 69-year-old
lens monomeric crystallin fractions.
Fig. 1. Experiment design. This is typical size exclusion chromatograms from aged lens soluble fraction.
The αA-Crys hetero-oligomer was eluted at earlytime. The αA-Crys monomeric fraction should beeluted at later in aged lens. Each fraction was measured by absorbance at 280 nm during chromatography, fractionated and applied for D/L analysis independently.

28024

REFERENCES:[1] N. Fujii et al., J Biol Chem. 287 (2012) 39992-40002.
[2] H, Sakaue, et al., Biochimica et biophysica acta. 1854(2015), 1-9.

CO6-4

LC–MS/MS Analysis of Post-translational Modifications of Lens Protein in
Patients with Retinitis Pigmentosa

Y. Ikeda, I. Kim1, S. Nakatake, Y. Murakami and N.
Fujii1
Department of Ophthalmology, Graduate School Medical Sciences, Kyushu University
1
Research Reactor Institute, Kyoto University
INTRODUCTION: Retinitis pigmentosa (RP) is a groupof inherited retinal degeneration diseases resulting fromphotoreceptor cell death and are frequently associatedwith cataract. We previously showed that chronic inflammation plays a role in the pathology of RP and could
pose a risk of the development of cataract formation.
The aim of this study was to identify the
post-translational modifications that occur in lens protein of RP patients during inflammatory process.

EXPERIMENTS: Lens samples were collected duringcataract surgery. This study was approved by the Institutional Review Board of Kyushu University Hospital(Fukuoka, Japan) and was conducted in accord with thetenets of the Declaration of Helsinki on Biomedical Research Involving Human Subjects. Informed Consent for
the research was obtained from all patients. Sample
preparation was performed as described in our previous
study [1]. Samples were homogenized in 50 mM sodium
phosphate buffer (pH 7.4), 150 mM NaCl, 1 mM phenylmethylsulfonyl fluoride (PMSF), 1 mM EDTA byultrasonication and fractionated into water-soluble (WS)and water-insoluble (WI) fractions by centrifugation at
12,000 × g for 20 min at 4 °C. The WI proteins weredissolved in 8 M urea, and the urea concentration was

28045

then diluted to less than 1 M in the same buffer before
the enzymatic digestion. The WS proteins were digested
with trypsin for 17 h at 37 °C in 50 mM sodium phosphate buffer (pH 7.4), 150 mM NaCl at an enzyme-to-substrate ratio of 1:50 (mol/mol). The WI proteins were digested with trypsin for 17 h at 37 °C in 50
mM sodium phosphate buffer (pH 7.4), 150 mM NaCl, 1
M urea, 1 mM CaCl2 at an enzyme-to-substrate ratio of
1:50 (mol/mol). A nano-flow HPLC system was used
for liquid chromatography (LC). Mass spectrometry(MS) was performed on an ion trap system. Peptides(500 ng) resulting from digestion with trypsin were separated by nano-flow HPLC using a C18 column(L-column, 0.1 × 150 mm) with a linear gradient of
5%–60% acetonitrile in the presence of 0.1% formic acidat a flow rate of 0.5 µL/min over 120 min and analyzed
by Proteome Discoverer 1.0 software. MS analysis was
carried out by alternating between full MS and MS/MS
scans. The MS/MS scan used the collision-induced dissociation (CID) mode with dynamic exclusion function.
RESULTS: Post-translational modifications including
oxidation and deamidation was detected in several lensproteins, such as α- and β-crystallins in patients withRP.
REFERENCE:[1] Kim I, et al . Site specific oxidation of amino acidresidues in rat lens γ-crystallin induced by low-dose
γ-irradiation. Biochem Biophys Res Commun. 466(2015) 622-628.

CO6-5

Purification, Crystallization, and X-ray Diffraction Study of Lysozyme in D2O
and H2O Solution.

T. Chatake, S. Fujiwara1, I. Tanaka2
Research Reactor Institute, Kyoto University
1
Quantum Beam Science Research Directorate, National
Institutes for Quantum and Radiological Science andTechnology
2
Faculty of Engineering, Ibaraki University
INTRODUCTION: Neutron scattering length of hydrogen (H) and its isotope deuterium (D) are remarkably
different, and such isotope effect is widely utilized inneutron experiments. In particular, the contrast analysis
between deuterated and non-deuterated sample is themain method in small angle neutron scattering (SANS)
for biology, because H content of biomacromolecule isabout half of all atoms in the molecule. In SANS, deuteration is used for labeling arbitrarily a part of macromolecular complex, simultaneously it decrease backgroundnoise of neutron scattering. In previous studies, we developed deuterium/hydrogen (D/H) contrast technique forneutron protein crystallography (NPC) [1]. This technique has great advantages in determining and evaluatinghydrogen atoms, especially, it is very powerful for visualizing water molecules (D2O/H2O) surrounding proteins.
The hydration structure is very important for folding andfunction of protein. In order to compare hydration structures of various kinds of proteins, we are crystallizing theproteins and carried out preliminary diffraction studies
using X-ray.
Here, we report purification, crystallization, and X-ray
diffraction study of lysozyme in D2O and H2O solution.
EXPERIMENTS: Hen egg white lysozyme (Sigma
Aldrich) was purified prior to crystallization. 100 mg
lysozyme power was solved in 3 mL of 50 mM sodium
acetate (NaAc) buffer (pH5.0). The lysozyme solution
was 0.22 mm-filtered, and then applied on GE Hiscreen
CatopSP Impres ion-exchange column (CV:4.7 mL), lysozyme was eluted by graduation from 0 M to 1 M NaClin the 50 mM NaAc buffer (pH 5.0). The eluted lysozyme
solution was dialyzed against 50 mM NaAc buffer (pH4.5) overnight, and then concentrated to be 40 mg/mL bycentrifuge concentration.
Crystallization for preliminary X-ray diffraction experiment was carried out sitting drop vapor diffusion method.
Reservoir solutions contained 0.8, 1.0, or 1.2 M NaCl in
the NaAc buffer (pH4.5). Each droplet was prepared bymixing 20 µL of 40 mg/mL lysozyme solution and 20 µL
of reservoir solution. Crystallization plates were stored at
20 °C. The same crystallization was performed using
D2O solution, in which deuteration was carried out therepeats of buffer exchange from H2O buffer to D2O buff-

28046

er.
Preliminary X-ray diffraction experiments were carriedout at beamline NW12 of the synchrotron facility in
Photon Factory. Deuterated and non-deuterated crystals
were sealed in glass capillaries with each buffer, respectively, and synchrotron experiments were carried out atroom temperature (300K). X-ray diffraction images werecollected by the helical scanning method in order to avoid
serious radiation damage on the crystals. 200 oscillation
images were taken with Δω = 1° and t = 1 sec. Since considerable numbers of low-resolution diffractions weresaturated on the detector, two data sets were taken foreach of D2O- and H2O-crystals with and without attenuator. Diffraction spots on the images were indexed, integrated, and merged by the program HKL2000.
RESULTS: After two weeks one or few large crystals
emerged in droplets with the reservoir solution of 0.8 or
1.0 M NaCl. The side-length of these crystals were atleast larger than 0.7 mm, and sometimes larger than 1.0
mm. In the present study, purification process seems to
improve crystal size of lysozyme.

Fig. 1. Lysozyme crystal used for X-ray experiments. H2O-crystal (right) and D2O-crsytal (left)
was sealed in a capillary with a diameter of ~ 1 mm.
Both crystals belong to the same space group P43212,
with the similar cell dimensions (a=b=79.2 Å, c=38.0 Å
for H2O crystal, a=b=79.2 Å, c=37.9 Å for the D2O crystal), suggesting the isomorphousness between the two
crystals. For the H2O crystal, 1.35 Å X-ray data could beobtained with the completeness and Rmerge of 99.9% and6.9%, respectively. Meanwhile, for the D2O crystal, 1.45
Å X-ray data could be obtained (completeness and Rmerge
were 99.8% and 6.90%). In order to compare the two
crystal structures, structure determinations are in progress.
REFERENCE:[1] T. Chatake and S. Fujiwra, Acta Crystallogra. D72(2016) 71-82.

CO6-6

Measurement of Transmittance Spectra of a Cryo-Sectioned Tissueof Brain Tumor C6 Model in the Sub-Terahertz Reagion-IV

T. Takahashi and N. Miyoshi1
Research Reactor Institute, Kyoto University
1
National University of Kyoto Institute of Technology

INTRODUCTION: The accelerator-based radiation
source in the millimeter and terahertz wave region hasvery attractive feature for the spectroscopy. Coherent
transition radiation (CTR), which has been emitted fromthe short bunches of electrons at the KURRI-LINAC, hasbeen used to observe the transmittance spectra of a sectioned tissue of raw brain tumor C6 model as a collaborate study in the research reactor institute, Kyoto university. The absorption spectra in the sub-terahertz region
had been not so clear for the raw tumor tissue although
Ashworth-PC. et al. [1] had reported for the excised human breast cancer by a terahertz pulsed spectroscopy
observed at 320 GHz, which was estimated a longer relaxation time component of the induced electricity forwater molecules [2-3] in the raw tumor tissue for three
years at the linear analysis.
We also estimated what kind of water molecules become
dominant in the viable and necrotic cancer regions by thedifferent measurement method as an aim of 2D mapping
study.
EXPERIMENTS: (1) Instrument of Near-field intera-hertz region: The experiment was performed at thecoherent radiation beamline [4] at the 40-MeV L-band
linac of the Research Reactor Institute, Kyoto University.
The THz-wave source was CTR emitted from an aluminum foil with 15-μm thickness. The radiation was detected by a liquid helium cooled Si bolometer. The conical cone with an aperture 260 μm in diameter was used as
the illumination probe and its F-number was 2.5. The
spectrum of CTR was measured by a Martin-Puplett typeinterferometer.
(2) Sample preparation: A cryo-sectioned (thickness=100m) tissue was prepared from the raw C6 glial tumor
model using a Cryo-section (C) Maker (Leica) and wassealed sandwich-type with polyvinylidene chloride(PVDC) film (thickness=10 m), under freezing condition (-20 C) before the measurements. The rest large
block of the tumor tissue was fixed with 10% formaldehyde for 1 week and was made of paraffin block to sliceof 50 m film sample (P) with PVDC film.
RESULTS: The absorbance of the raw tissue at 16 cm-1
was larger than 0.1 comparing the paraffin sample which
was decreased of water contents by formaldehyde effectas shown in Figs. 1 and 2. Especially, the water contents
were distributed in the necrotic area (white area in28059

cryo-section). On the other hand, the absorbance at 19
cm-1 was distributed also in the necrotic area of the tumor
tissues which looks like paraffin contents (lipid). In conclusion, lipid and water contents were distributed lich in
the necrotic area of tumor tissue by this sub-THz LINAC
beam analysis. It was found the absorbance at 16 and 19
cm-1 were belonged as the water and lipid components,
respectively in tumor tissue. The condition of watercomponents should be more cleared in future, a clustermodel of the water molecules and the other absorbance inthis sub-THz region.

Fig. 1 Linear analysis of Cryo (C) and Paraffin (P)-sectioned samples.

Fig. 2 2D-Mapping Images of Cryo- and Paraffin-sectioned samples at 16 and 19 cm-1, respectively.
REFERENCES:[1] Phillip C. Ashuworth, et. al., Optics Express, 17(14):12444-12454 (2009).
[2] Toshiko Fukasawa, et al., Phys. Rev. Let., 95: 197802(2005).
[3] Hiroyuki Yada, et al., Chem. Phys. Let., 464: 166-170(2008).
[4] T. Takahashi, et al., Rev. Sci. Instrum. 69 (1998)
3770.

CO6-7 The Study for Development and Application of Tissue Equivalent Neutron Dosimeter
M. Oita, T. Kamomae1, T. Takada2 and K. Sakurai2
Graduate School of Health Sciences, Okayama University
1

Graduate School of Medicine, Department of Radiology,
Nagoya University
2

Research Reactor Institute, Kyoto University

INTRODUCTION: Recent years, the clinical application of boron neutron capture therapy (BNCT) has been
expected to make significant contributions to treatment for
intractable cancer such as glioblastoma multiforme andmelanoma. In BNCT, the boron (n,α)-reaction of theisotope 10B has a high cross section toward thermal
neutrons, and the produced alpha and lithium particles
have a short range on the micrometer scale. However, theneutron spectrum always spans a broad energy range,
which results in different dose components and biologicaleffects in tissue. Therefore, there are some difficulties ofneutron dosimetry in clinical practice.
A radiochromic film (RCF) is one of the most usefuldevices for the QA of radiotherapy equipment. The advantages of RCFs are their high spatial resolution, smallenergy dependence, tissue equivalence, andself-development without processing in a darkroom1. A
reflective-type RCF, e.g., GAFCHROMIC® EBT3, hasbeen developed for qualitative dosimetry such as stereotactic irradiation (STI) and intensity modulated radiotherapy (IMRT)2,3. In this work, the authors investigated the response of reflective-type RCF for neutron beam
as a tissue equivalent dosimeter.
EXPERIMENTS:
A reflective-type RCF, GAFCHROMIC® EBT3 (Ashland Inc., Wayne, NJ, USA)using an Americium–Beryllium (241Am–Be) neutron
source (74 GBq, 5×106 neutrons.s-1) with a cylindricaldesign (20 mm diameter by 30 mm long) made of thecorrosion-resistant alloy was evaluated in this study.
The RCFs were handled by the recommendation outlinedin the American Association of Physicists in Medicine
Task Group No. 55 report1.
For irradiation, 6.0 × 6.0 cm2 pieces of the RCF wereplaced at 1 cm, 4 cm, and 7 cm from just beneath thesource with slit window along one direction, and withbehind 1 mm acrylic plate along opposite direction in air(Fig.1). The RCF pieces were irradiated 180 min by thesource, respectively.
RESULTS: Fig.1 shows the geometry of irradiation of
RCFs by the 241Am-Be neutron source. Fig.2 shows thechange of pixel values of RCFs irradiated by the
241

Am–Be neutron source. There was significance difference of pixel values of irradiated RCFs by the neutron

28083

source. The change of pixel value of RCF piece between 1 cm and 4 cm was 1811, while the value with theacrylic plate was attenuated by 1513. The dose in former converted by X-ray calibration of the RCF in the air
were 36.2 cGy. Similarly, the dose of using a NaI scintillation survey meter was 15.3 cGy. Besides neutrons,
the RCFs were exposed to gamma rays coming fromevents taking place in the source itself and the surrounding moderator. Further analysis was needed of the response of RCFs with neutron spectrum and contributionsof gamma rays using Monte Carlo simulation. However,
the results suggested that the dosimetry using RCFs isimportant for a better knowledge of fast neutron flux distribution with the 241Am–Be source. Moreover, it would
be feasible for BNCT dosimetry in medical application.

Fig. 1. The geometry of irradiation of RCFs by the241
Am-Be neutron source.

Fig. 2. The change of pixel values of the RCFs irradiatedby the 241Am-Be neutron source.

REFERENCES:[1] Niroomand-Rad, Azam, et al. Medical physics
25 (1998), 2093-2115.
[2] Borca, Valeria Casanova, et al. Journal of appliedclinical medical physics 14 (2013).
[3] Fiandra, Christian, et al. Medical physics 40 (2013).