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iBNCTProject
H. Kumada, K. Takada, T. Aihara, A. Matsumura
H. Sakurai, T. Sakae
Proton Medical Research Centre, University of Tsukuba
Verification of dose estimation for Monte-
Carlo based treatment planning system
for boron neutron capture therapy
iBNCTProjectProgress of boron neutron capture therapy (BNCT)
Boron neutron capture therapy (BNCT) is based on the nuclearreaction that occurs when boron-10 is irradiated with neutrons of theappropriate energy to produce high-energy alpha particles and recoilinglithium-7 nuclei. Therefore BNCT is categorized to external beamtherapy using neutron beam. Clinical trials for BNCT is being performedusing research rectors so far. However in recent years, manyaccelerator-based neutron sources for BNCT are being developed.In Japan in particular, some devices have been generated enoughneutrons, and two facilities are already being carrying out clinicaltrials using cyclotron-based neutron source for BNCT.
University of Tsukuba is also developing a linac-base BNCT device.
Kyoto University
Research Reactor
Institute (Osaka)
National Cancer Center
Hospital (Tokyo)
Southern Tohoku BNCT Research
Center (Fukushima)University of Tsukuba (Ibaraki)
BNCT facilities in Japan
iBNCTProjectDevelopment of Peripheral Equipment for BNCT
【RFQ+DTL Type Linac for BNCT】
【Treatment Management System】
《B
ea
m T
ran
sp
ort
Syste
m》
《Patient Positioning System》《PG-SPECT》
《Neutron Monitor》
Proton BeamNeutronBeam
《Neutron Generator》
《Beryllium
Target》
スペクトル可変機構
中性子ターゲット
中性子
即発γ線検出器
10Bと中性子反応で生じる即発γ線
即発γ線SPECTベース・リアルタイム3D線量モニター
中性子遮蔽壁
陽子線
【Treatment Planning System】
Not only neutron generator with accelerator but also peripheral devices
which are needed to perform BNCT, are being developed.
Monte-Carlo based treatment planning system
Patient positioning system by using motion capture technology
Real-time neutron monitor, PG-SPECT etc.
Treatment room
Linac
iBNCTProjectDose estimation process with Tsukuba-Plan
Monte-Carlo Calculation
Set Material Set Region of Interest Set Irradiation
Condition
Dosimetry Mode
iBNCTProjectFeatures of Tsukuba-Plan
Tsukuba-Plan has employed “PHITS” as the dose calculation engine.PHITS is multi-purpose MC transport code, and it can determinedoses for neutrons, photons as well as protons, heavy ions.Therefore Tsukuba-Plan with PHITS enables to perform doseestimation for not only BNCT but also for external beam therapiesas particle therapy and X-ray therapy. And it is also adaptable tobrachytherapy.
➡ Dose estimation/treatment planning for each radiotherapy➡ Treatment planning for combined radiotherapy➡ Dose estimation for total dose given to a patient
And Tsukuba-Plan allows to estimate incidental dose caused bysecondary neutrons in particle therapy.
Furthermore, PHITS has “MKM” which can perform micro-dosimetry.Thus Tsukuba-Plan can determine equivalent dose based onmicro-dosimetry in addition to conventional way as “RBE xPhysical dose”
iBNCTProjectApplication of Tsukuba Plan to Proton therapy and X-ray therapy
1st
scatterer
MLC
Middle
collimator
BolusRidge filter
2nd
scatterer
Head phantom
Dose estimation for proton therapyProton therapy in University
of Tsukuba Hospital
X-ray Therapy 6 MVIrradiation field: 5 cm×5 cm
0.0%
20.0%
40.0%
60.0%
80.0%
100.0%
120.0%
0.0 100.0 200.0R
ela
tiv
e d
os
e
Depth in water (mm)
Measured data
PHITS calculation
0.0%
20.0%
40.0%
60.0%
80.0%
100.0%
120.0%
-80.0-60.0-40.0-20.0 0.0 20.0 40.0 60.0 80.0
Re
lati
ve
do
se
Distance from the beam axis(mm)
Measured data
PHITS calculation
Comparison results of PDD and OCR for 6-MV beam
Target
Region
X-ra y Bea mD i r e c t i o n
Two-field fractionated X-ray irradiation
Proton
Therapy
0%
20%
40%
60%
80%
100%
120%
-50 -40 -30 -20 -10 0 10 20 30 40 50
Re
lati
ve
do
se
(%
)
Distance from the beam axis (mm)
Snout 120, MD 90 (Center of SOBP)
Measurement
PHITS calculation
Measure Depth:90 mm SOBP:40 mm
0.0%
20.0%
40.0%
60.0%
80.0%
100.0%
120.0%
0.0 50.0 100.0 150.0
Re
la t
ive
do
se
Depth in water (mm)
Measurement data
PHITS calculation
2D dose distribution
Target
Region
Poster No. 124: H. Kumada, et al., “Application expansion of the Monte-Carlo based treatment planning system for BNCT to particle radiotherapy and X-ray therapy.”
Secondary neutron dose estimation in Proton therapy
Proton dose distributions Secondary neutron dose distributions
Poster No. 125: K. Takada, et al., “Fundamental study for practical application of radiotherapy treatment planning system capable of evaluation neutron dose generated by various radiotherapy beams.”
iBNCTProject
Verification for the dose estimation
performance of Tsukuba Plan for
boron neutron capture therapy (BNCT)
iBNCTProject
Tsukuba Plan
Southern Tohoku Hospital, BNCT Center
National Cancer Center Hospital
Irradiation roomAccelerator
Kyoto University KUR, BNCT facility
University of Tsukuba, iBNCT Facility
Verification in all BNCT facilities in Japan
iBNCTProject
JRR-4 in JAEA
Create three neutron source for BNCT
iBNCT accelerator-based neutron source for BNCT in University of Tsukuba
Water phantomBeam Port
Water Phantom
KUR in Kyoto University Research Reactor
Water Phantom
Thermal neutron flux distributions in a cylindrical water phantom
0.0E+00
5.0E+08
1.0E+09
1.5E+09
2.0E+09
2.5E+09
3.0E+09
3.5E+09
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0T
he
rma
l N
eu
tro
n F
lux (
n/c
m2s
)
Depth from phantom surface (cm)
グラフタイトル
Experimental Values
Tsukuba Plan Calculations
iBNCTProjectVerification (2) in iBNCT accelerator-based neutron source
Experiments in iBNCT facility
in Univ. Tsukuba
Water phantom experiments
0.0E+00
2.0E+07
4.0E+07
6.0E+07
8.0E+07
1.0E+08
1.2E+08
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
熱中性子束
(n
/cm
2 ・s)
Phantom 表面からの深さ (cm)
陽子電流:平均0.09mA 水ファントム実験結果
金箔実験値
LiCAF実験値
モンテカルロ計算値
Experimental values for
thermal neutron flux
To confirm characteristics of neutron
beam emitted from beam aperture,
several experiments with a water
phantom had been carried out.
For measurement of thermal neutron
flux distribution, some gold wires and
gold foils were set inside the phantom,
and the distributions were measured.
Some scintillators detectable thermal
neutrons were also located in the
phantom.
For gamma-ray dose distribution,
many TLDs were set in the phantom,
and measured the gamma-ray dose
distribution.
Dose estimations by using Tsukuba Plan
3D-Model of water phantom
Thermal neutron flux distributions
Calculation Model
Compare
iBNCTProjectComparison with Tsukuba-Plan Calculations and Experiments
Calculation time
Intel Xeon E5
32 Core Workstation X 3
= 90 Core parallel computing
Calculation time : about 18 min.
(statistical errors around target
region < 5% )
Co
mb
ina
tion
Thermal neutron flux distributions
0.0E+00
1.0E+08
2.0E+08
3.0E+08
4.0E+08
5.0E+08
6.0E+08
7.0E+08
8.0E+08
9.0E+08
0.0 2.0 4.0 6.0 8.0 10.0
Th
erm
al N
eu
tro
n F
lux
(n/c
m2s)
Depth from surface (cm)
Calculations
Measurements
0.0E+00
5.0E+07
1.0E+08
1.5E+08
2.0E+08
2.5E+08
3.0E+08
3.5E+08
4.0E+08
4.5E+08
5.0E+08
0.0 2.0 4.0 6.0 8.0 10.0
Therm
al N
eutr
on F
lux
(n/c
m2s)
Distance from center (cm)
Calculations Surface
Measurements Surface
Calculations Depth 0.5cm
Meaurements Depth 0.3cm
Beam central axis
Lateral distributions
surface
Depth from surface: 0.5cm
0.0E+00
5.0E+07
1.0E+08
1.5E+08
2.0E+08
2.5E+08
3.0E+08
3.5E+08
4.0E+08
4.5E+08
5.0E+08
0.0 2.0 4.0 6.0 8.0 10.0
Therm
al N
eutr
on F
lux
(n/c
m2s)
Distance from center (cm)
Calculations Surface
Measurements Surface
Calculations Depth 0.5cm
Meaurements Depth 0.3cm
surface
Depth from surface: 0.5cm
Normalization point:
Depth: 5cm
0.5
Gamma-ray dose rate distributions
0.0E+00
5.0E-01
1.0E+00
1.5E+00
2.0E+00
2.5E+00
3.0E+00
3.5E+00
4.0E+00
0.0 2.0 4.0 6.0 8.0 10.0
Ga
mm
a-r
ay
do
se r
ate
(G
y/h)
Depth from surface (cm)
Calculation
Measurements
0.0E+00
5.0E-01
1.0E+00
1.5E+00
2.0E+00
2.5E+00
3.0E+00
3.5E+00
4.0E+00
0.0 2.0 4.0 6.0 8.0 10.0
Gam
ma-r
ay d
ose rate
(G
y/h
)Distance from center (cm)
Calculation Surface
Measurements Surface
Calculation Depth 2cm
Measurements Depth 2cm
Calculation Depth 2cm
Measurements 10cm
Beam central axis
Lateral distributions
surface
Depth: 2cm
Depth: 10cm
10
iBNCTProject
Calculation models Calculation Results
Set irradiation conditionsSet ROI and target point
Dose estimation for realistic human model
iBNCTProject
0
10
20
30
40
50
60
70
80
90
100
0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0
グラフ タイト ル
iBNCT Left Brain
KUR Left Brain
JRR-4 Left Brain
JRR412cmBeam Left Brain
iBNCT Tumor
KUR Tumor
JRR-4 Tumor
JRR412cmBeam Tumor
Vo
lum
e(%)
Dose(Gy-Eq)
iBNCT Source・Tumor
KUR Source・Tumor
JRR4, 10cm port・Tumor
JRR4, 12cm port・Tumor
Influence for difference for beam sources, D.V.H.
iBNCTProjectFutures: Estimation for whole body exposure
Dose estimation
for whole body
exposure using
Tsukuba-Plan
Near future
Measurement for whole
body exposure in
BNCT using a whole
body phantomDose estimation for whole body exposure
in BNCT irradiation using PHITS
(a)人体ファントム照射シミュレーションモデル
(b)熱中性子束2次元分布計算結果
人体ファントム
ビーム孔
At the moment
iBNCTProject
University of Tsukuba is being developed the Monte Carlo based
treatment planning system “Tsukuba-Plan” for BNCT.
Tsukuba-Plan has employed PHITS as a MC dose calculation engine.
Tsukuba-Plan enables to perform dose estimation/ treatment planning
for not only BNCT but also particle therapy, X-ray therapy. And the
system is also applicable to the dose estimation for brachytherapy.
Incidental doses caused by secondary neutrons in radiation
therapy are also able to be estimated.
Conclusions
At present, several verification in BNCT dosimetry for Tsukuba-
Plan are being carrying out.
In comparison between measurements from water phantom
experiments and calculations, distributions for thermal neutron flux
and gamma-ray dose in the phantoms were in good agreement.
Further verifications are planned in order to put into practical use of
BNCT treatment and to get license for pharmaceutical approval.
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