Energy calibration
Energy calibration
Energy calibration
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TEPC for Boron Neutron<br />
Capture Therapy<br />
Hsiu-Wen Hsiao<br />
934534<br />
May 2, 2007
• Introductions<br />
- BNCT<br />
Outline<br />
- Mixed radiation field dosimetry<br />
• Materials and Methods<br />
- The dual counter microdosimteric technique<br />
- Gas-filled and Measurement system<br />
- <strong>Energy</strong> <strong>calibration</strong>s<br />
• Results<br />
• Future works
BNCT (Boron Neutron Capture Therapy)<br />
thermal<br />
neutron<br />
10 B 11B<br />
7 Li<br />
nucleus<br />
4 He nucleus<br />
(α particle)<br />
γ-ray
BNCT facilities operating in the world<br />
• FiR-1 reactor Finland<br />
• HFR Petten<br />
• R2-0 reactor at Studsvik Sweden<br />
• RA-6 reactor Argentina<br />
• KUR/JRR4 Japan<br />
• MITR-II research reactor USA<br />
• LCR-I Czech Republic<br />
THOR (Tsing-Hua Open-pool Reactor), Taiwan
Mixed radiation field dosimetry<br />
• Mixed field<br />
– Fast neutron<br />
– Epithermal neutron<br />
–Photon<br />
–Dfast n – recoil protons<br />
–Dthermal n – 14N(n,p) 14C –Dphoton – 1H(n,γ) 2H – from mixed field photon <br />
– 10B(n,α) 7 The Dual Counter Microdosimetric technique<br />
-- paired low-pressure TEPC<br />
Dn Li<br />
• Within patient<br />
–D BNC
Microdosimetric Parameters<br />
Lineal energy (y)<br />
<br />
d<br />
Medium<br />
ε<br />
y =<br />
<br />
(J/m, keV/μm)<br />
ε = energy imparted<br />
= mean chord length<br />
= 4V/A = (2/3)d
Materials and Methods
The dual counter<br />
microdosimetric technique<br />
• Paired low-pressure TEPC<br />
- Boron-loaded A-150 TE counter<br />
- Non Boron-loaded A-150 TE counter<br />
Diameter = 2.5 cm<br />
Wall = 2.5 mm<br />
A-150 plastic<br />
with/ without<br />
boron loaded<br />
• Spectrum Boron-loaded - Spectrum NonBoron-loaded<br />
Spectrum BNC<br />
D BNC
The appearances of TEPC<br />
Boron concentration<br />
of wall<br />
0 ppm<br />
50 ppm<br />
commercial
TEPC<br />
• Anode<br />
– Material:Copper/Beryllium (Cu 98% / Be 2%)<br />
– Diameter:0.025 mm<br />
0.046 mm<br />
• Wall<br />
– Material: A-150 TE plastic ( and B 2 O 3 )<br />
– Thickness:2.5 mm<br />
1.25 mm<br />
• Cavity<br />
– Diameter:2.5 cm<br />
1.25 cm
Gas-filled system at NSRRC<br />
Valves<br />
TEPCs<br />
Vacuum pump<br />
manometer<br />
A gas cylinder with<br />
propane-based TE gas
The TEPC measurement system<br />
Oscilloscope<br />
H.V.<br />
Amplifier<br />
preAmp<br />
TEPC<br />
MCA
Operating condition<br />
<strong>Energy</strong> <strong>calibration</strong><br />
THOR50c beam<br />
Flow chart<br />
Microdosimetry spectrum<br />
Dose analysis<br />
Gas pressure<br />
Operating voltage<br />
Proton edge<br />
Alpha edge<br />
Gamma ray field<br />
TE (0 ppm、commercial)<br />
TE+B (50 ppm)
Operating condition<br />
<strong>Energy</strong> <strong>calibration</strong><br />
THOR50c beam<br />
Flow chart<br />
Microdosimetry spectrum<br />
Dose analysis<br />
Gas pressure<br />
Operating voltage<br />
Proton edge<br />
Alpha edge<br />
Gamma ray field<br />
TE (0 ppm、commercial)<br />
TE+B (50 ppm)
Simulation of small volumes-1<br />
Δx t<br />
E t<br />
a cell<br />
(tissue)<br />
Δx g<br />
E g<br />
counter<br />
Propane-based<br />
TE gas<br />
55% C 3 H 8 ,<br />
39.6%CO 2 ,<br />
5.4%N 2<br />
(TEPC)
Simulation of small volumes-2<br />
E t<br />
Δx t<br />
(tissue)<br />
E g<br />
Δx g<br />
(TEPC)<br />
⎪<br />
⎪<br />
⎩<br />
⎪<br />
⎪<br />
⎨<br />
⎧<br />
ΔΧ<br />
⎟<br />
⎠<br />
⎞<br />
⎜<br />
⎝<br />
⎛<br />
=<br />
ΔΧ<br />
⎟<br />
⎠<br />
⎞<br />
⎜<br />
⎝<br />
⎛<br />
=<br />
g<br />
g<br />
g<br />
g<br />
t<br />
t<br />
t<br />
t<br />
dx<br />
dE<br />
1<br />
E<br />
dx<br />
dE<br />
1<br />
E<br />
ρ<br />
ρ<br />
ρ<br />
ρ<br />
g<br />
g<br />
g<br />
t<br />
t<br />
t<br />
dx<br />
dE<br />
1<br />
dx<br />
dE<br />
1<br />
ΔΧ<br />
⎟<br />
⎠<br />
⎞<br />
⎜<br />
⎝<br />
⎛<br />
=<br />
ΔΧ<br />
⎟<br />
⎠<br />
⎞<br />
⎜<br />
⎝<br />
⎛<br />
ρ<br />
ρ<br />
ρ<br />
ρ<br />
g<br />
g<br />
t<br />
t<br />
ΔΧ<br />
=<br />
ΔΧ ρ<br />
ρ<br />
g<br />
g<br />
g<br />
g<br />
t<br />
t<br />
t<br />
t<br />
T<br />
P<br />
ΔΧ<br />
ρ<br />
T<br />
P<br />
ΔΧ<br />
ρ =<br />
t<br />
t<br />
g<br />
g<br />
t<br />
g<br />
t<br />
g<br />
P<br />
T<br />
T<br />
ΔΧ<br />
ΔΧ<br />
ρ<br />
ρ<br />
P =
Simulation of small volumes-3<br />
ρ ΔΧ T<br />
P P<br />
t t g<br />
g =<br />
t<br />
ρg ΔΧg Tt<br />
ρ g = 1.826 x 10 -3 g/cm 3 at P t = 760 torr, T g = 293 o K<br />
ΔX t = 1 μm;ΔX g = 2.5 cm<br />
ρ t = 1 g/cm 3 ; T t = 310.5 o K<br />
1 0.0001 293<br />
Pg= × × × 760<br />
0.0018 2.5 310.5<br />
= 16.87 torr ~<br />
17 (torr)
Operating condition<br />
<strong>Energy</strong> <strong>calibration</strong><br />
THOR50c beam<br />
Flow chart<br />
Microdosimetry spectrum<br />
Dose analysis<br />
Gas pressure<br />
Operating voltage<br />
Internal alpha source<br />
Proton edge<br />
Alpha edge<br />
TE (0 ppm、commercial)<br />
TE+B (50 ppm)
Internal alpha source <strong>calibration</strong><br />
– commercial TEPC<br />
internal alpha source<br />
-- Cm-244
• Spectrum of alpha<br />
from ICRU Report 36<br />
Low -energy<br />
delta rays<br />
Calibrations<br />
128 (keV/μm)<br />
straggling<br />
y<br />
= ×<br />
h<br />
p<br />
y h<br />
p<br />
constant
Operating condition<br />
<strong>Energy</strong> <strong>calibration</strong><br />
THOR50c beam<br />
Flow chart<br />
Microdosimetry spectrum<br />
Dose analysis<br />
Gas pressure<br />
Operating voltage<br />
Internal alpha source<br />
Alpha edge<br />
Proton edge<br />
TE (0 ppm、commercial)<br />
TE+B (50 ppm)
<strong>Energy</strong> Calibration — alpha edge<br />
• Simulation:<br />
Boron<br />
~ 50 ppm<br />
Cell membrane<br />
B-10 drugs<br />
A-150 TE plastic<br />
Propane-based<br />
TE gas<br />
cytoplasm<br />
nucleus
<strong>Energy</strong> Calibration — alpha edge<br />
10 B (n,α) 7 Li<br />
10 B (n,α) 7 Li
counts<br />
<strong>Energy</strong> Calibration — alpha edge<br />
700<br />
600<br />
500<br />
400<br />
300<br />
200<br />
100<br />
1um<br />
0<br />
0.1 1 10 100 1000<br />
y (keV/um) 386 keV/μm<br />
counts<br />
6000<br />
5000<br />
4000<br />
3000<br />
2000<br />
1000<br />
6 um<br />
0<br />
0.1 1 10 100 1000<br />
y (keV/um) 216 keV/μm
Operating condition<br />
<strong>Energy</strong> <strong>calibration</strong><br />
THOR50c beam<br />
Flow chart<br />
Microdosimetry spectrum<br />
Dose analysis<br />
Gas pressure<br />
Operating voltage<br />
Internal alpha source<br />
Alpha edge<br />
Proton edge<br />
TE (0 ppm、commercial)<br />
TE+B (50 ppm)
<strong>Energy</strong> Calibration — proton edge<br />
• According to papers:<br />
Proton edge<br />
Simulated<br />
diameter<br />
(μm)<br />
Proton edge<br />
(keV/μm)<br />
1 6<br />
146 105
Operating condition<br />
<strong>Energy</strong> <strong>calibration</strong><br />
THOR50c beam<br />
Flow chart<br />
Microdosimetry spectrum<br />
Dose analysis<br />
Gas pressure<br />
Operating voltage<br />
Internal alpha source<br />
Alpha edge<br />
Proton edge<br />
TE (0 ppm、commercial)<br />
TE+B (50 ppm)
Measurements of spectrum<br />
• Epithermal neutron beam of THOR<br />
Dual counter<br />
(TE, TE+B)<br />
In air: at beam exit 7 cm<br />
In phantom<br />
Same depth but different air gap<br />
Different depths
Results
<strong>Energy</strong> Calibration —<br />
Internal alpha source<br />
• Commercial TEPC<br />
• Spectrum of <strong>calibration</strong> -- 1 μm<br />
counts<br />
200<br />
150<br />
100<br />
50<br />
0<br />
0 200 400 600 800 1000 1000<br />
channel (ch)<br />
1.8 hrs<br />
8 hrs<br />
Shift ~15 channels<br />
128 keV/μm
<strong>Energy</strong> Calibration —<br />
detector drift characteristics<br />
• The possible reasons are as follows,<br />
- Outgassing of the plastic<br />
- Temperature shift<br />
- The plastic absorbs some of the gas after it has<br />
been in the vacuum.<br />
improved by filling it and waiting for a<br />
few hours before using it.
<strong>Energy</strong> Calibration —<br />
Internal alpha source<br />
• Calibration curve for alpha edge shift :<br />
channel of alpha edge (ch)<br />
520<br />
polynomial fit:<br />
y = 499.77796 + 4.58089X - 0.22175X^2<br />
500<br />
0 2 4 6 8 10<br />
time interval after filling TE gas (hrs)
yf(y)<br />
0.5<br />
0.4<br />
0.3<br />
0.2<br />
0.1<br />
Spectrum of Pu-239 source<br />
• Commercial TEPC -- 6 μm<br />
• Measurement time = 2 hrs<br />
1H(n, γ)H2<br />
0.0<br />
0.1 1 10 100 1000<br />
y (keV/um)<br />
Pu-239 source<br />
Recoil proton<br />
yd(y)<br />
0.5<br />
0.4<br />
0.3<br />
0.2<br />
0.1<br />
Pu-239 source<br />
1H(n, γ)H2<br />
0.0<br />
0.1 1 10 100 1000<br />
y (keV/um)<br />
Recoil proton<br />
Proton edge<br />
105 keV/um
Future works
Future works<br />
Operating condition<br />
<strong>Energy</strong> <strong>calibration</strong><br />
THOR50c beam<br />
Microdosimetry spectrum<br />
Dose analysis<br />
Gas pressure<br />
Operating voltage<br />
Internal alpha source<br />
Alpha edge<br />
Proton edge<br />
TE (0 ppm、commercial)<br />
TE+B (50 ppm)
References<br />
C. S. Wuu et al., Microdosimetry for Boron Neutron<br />
Capture Therapy. Rad. Res. 130, 355-359, 1992.<br />
Hsiao-Jay Huang, Microdosimetry Study of Neutrons using the<br />
Tissue Equivalent Proportional Counter, NTHU. 2004.<br />
Anthony J. Waker, Miniature tissue-equivalent proportional<br />
counters for BNCT and BNCEFNT dosimetry, Med. Phy., Vol.<br />
28, No. 9, Sep. 2001.<br />
Srdoc, D. Experimental Technique of Measurement of<br />
Microscopic <strong>Energy</strong> Distribution in Irradiated Mater using<br />
Rossi Counters. Rad. Res. 43, 302-319, 1970.<br />
David Tattam and T. Derek Beynon, Use of low-pressure<br />
tissue equivalent proportional counters for the dosimetry of<br />
neutron beams used in BNCT and BNCEFNT, Med. Phy.,<br />
Vol. 27, No. 3, March 2000.
Thanks for your attention~☺
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