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Han Rim Lee1, Jong Hoon Park1, Young-su Kim1,
Won Gyun Jung2, Chan Hyeong Kim1
1Department of Nuclear Engineering, Hanyang University 2Heavy-ion Clinical Research Division, Korean Institute of Radiological &
Medical Sciences
Development of Data Acquisition Systems for Gamma Vertex Imaging System for Proton Dose Verification
53rd Annual Conference of the Particle Therapy Co-Operative Group
2
Gamma vertex imaging
C. H. Kim, J. H. Park, H. Seo, and H. R. Lee, Med. Phys. vol. 39, no. 10,
pp. 1001-1006, 2012.
3
Performance estimation with Geant4 simulation
Geant4 simulation
Simulation condition
• Primary particles: 1.2 × 109
• Phantom: soft tissue (30 cm × 30 cm × 40 cm)
• Incident position(d): 5 cm
• Energy window: 4-10 MeV
• Proton energy: 80, 150, 200 MeV
Proton beam
4
Proton beam
5
Research objectives
Develop the prototype gamma vertex imaging (GVI)
system
- Electronic read-out system for hodoscope
- Electronic read-out system for calorimeter
- DAQ and image reconstruction system
Test the performance of the prototype system
- Energy resolution and Vrms of hodoscopes
- Energy calibration of calorimeter
- 2D image for beta source
- 2D image for gamma source
- 2D image for 4.4 MeV gamma of Am-Be source
6
Hodoscope (double-sided silicon strip detector)
Double-sided silicon strip detector
(DSSD)
Electron
converter
Hodoscope
Hodoscope
Calorimeter e
e
Source
e
Specification of DSSD
- Detector type: W1-type (Micron Semiconductor Ltd., UK)
- Active area: 5 × 5 cm2
- Strip number: 16 for each side (strip pitch: 3.125 mm)
- Detector thickness: 1st DSSD (145 μm), 2nd DSSD (300 μm)
- Bias voltage: 20 V (145 μm), 30 V (300 μm)
7
CSP Slow amplifier
Fast amplifier LED
Primary
encoder
Multiplexer
Position DAC
Energy
DSSD
signal
(16 ch)
CR-110
(Cremat Inc.,
MA) for p-side
eV-5094 (eV
products, PA)
for n-side
Electronic read-out system for hodoscope (DSSD)
In-house system
8
Development of shaping amplifier
Shaping Amplifier
• Amplify and shape the signals in the form of Gaussian
• CR differentiator + active filter (2nd-order Sallen-key low pass filter)
• Shaping time= 100 (for trigger), 250 (for energy) ns, Gain= 10
Board layout
Shaping amplifier Circuit design
9
Development of multiplexing system
Board layout
Circuit design
Multiplexing system
10
Amplification Shaping
amplifier
Multiplexing system
(P-side)
Multiplexing system
(N-side)
CR-110(P-side)
eV-5094(N-side)
Developed electronic read-out system
11
Electronic read-out system for calorimeter (plastic scintillation detector)
Scintillator: EJ200 (thickness: 2cm, Eljen technology)
Photomultiplier (9102, ET Enterprises Ltd)
- Quantum eff. : 28% @ 400 nm - Gain: 2 × 104 @ 750 V
Voltage divider
Preamplifier (AMP-1000 Preamplifier)
- Pulse fall time: ~ 50 µs - Maximum signal height: ±10 V
Amplifier (in-house shaper, 250 ns)
SCIONIX(NL) Electron converter
1st DSSD
2nd DSSD
Calorimeter e
e
Source
e
12
Developed prototype imaging system
1st DSSD
2nd DSSD
Electronic read-
out system for
DSSD
Beryllium
converter
Plastic
scintillation
detector
13
DAQ and image reconstruction system
Data analysis and image
reconstruction system
1. Digitizer control and data acquisition
2. Determination of energy and time
3. Check time and energy window
PXI based data acquisition system
Controller (PXIe-8133)
- Inter Core I7-820QM quad-core
processor (1.73 GHz)
Chassis (PXIe-1082)
Digitizer (PXI-5105)
- Input number: 8 channel
- Sampling rate: 60 MS/s per channel
- Input range: ±25 mV - ±15 V
- Resolution: 12-bit 4. Image reconstruction
14
Test results
15
Performance test: energy resolution of hodoscopes
Energy resolution of hodoscopes (DSSD)
- First DSSD P-side: 28.8% ± 0.20%p (59.5 keV), 13.3% ± 0.12%p (122 keV)
- First DSSD N-side: 30.8% ± 0.27%p (59.5 keV), 14.0% ± 0.22%p (122 keV)
- Second DSSD P-side: 20.6% ± 0.15%p (59.5 keV), 8.9% ± 0.08%p (122 keV)
- Second DSSD N-side: 25.2% ± 0.22%p (59.5 keV), 11.0% ± 0.17%p (122 keV)
241Am (59.5 keV) 57Co (122 keV)
First DSSD (145 μm) P-side
16
Performance test: Vrms of DSSD
Vrms (V) Vrms (keV) 0.153 3.35 0.160 4.53 0.145 3.58 0.152 3.60 0.143 3.15 0.151 3.80 0.157 3.42 0.152 2.98 0.149 3.47 0.156 3.59 0.138 3.45 0.147 4.19 0.142 3.51 0.148 2.62 0.142 3.16 0.149 3.53
Vrms (V) Vrms (keV) 0.162 5.16 0.148 3.90 0.154 3.77 0.153 3.45 0.148 3.82 0.153 4.00 0.157 3.99 0.146 4.14 0.158 4.27 0.144 3.93 0.159 4.00 0.148 3.88 0.149 4.30 0.156 3.66 0.151 3.48 0.168 5.05
P-side N-side
First DSSD (145 μm)
3.50 ± 0.44 keV 4.05 ± 0.48 keV
Vrms (V) Vrms (keV) 0.128 5.05
0.124 5.58
0.113 5.98
0.119 3.97
0.121 4.55
0.115 3.98
0.123 4.64
0.122 3.79
0.117 5.10
0.118 4.53
0.116 4.48
0.121 4.36
0.118 3.63
0.111 4.16
0.115 3.68
0.115 4.43
P-side N-side
Second DSSD (300 μm)
4.49 ± 0.17 keV
Vrms (V) Vrms (keV) 0.160 4.61
0.151 6.97
0.149 5.79
0.157 6.45
0.158 5.24
0.150 6.78
0.159 6.52
0.153 5.85
0.158 4.93
0.155 6.27
0.157 5.66
0.148 6.43
0.158 4.34
0.151 5.45
0.151 5.34
0.161 5.17
5.73 ± 0.20 keV
Minimum energy deposition of Compton electron to DSSD
- First DSSD: 50.68 keV
- Second DSSD: 104.85 keV
17
Energy calibration using Compton edges
Y(channel) = 0.84 × X(energy) + 2.3
Adj. R-square = 0.998
18
Test results for beta source
19
2D image for beta point source
90Sr (Beta, 0.546 and 2.284 MeV)
Position: 1.8 mm, -3.5 mm
Original position (2.0 mm, -3.5 mm)
FWHM: 17.8 mm
Converter: none
Source to 1st DSSD distance: 26.5 mm
Source activity: 0.9 µCi
Measurement time: 30 min
Energy threshold: 1 MeV
20
2D image for beta point source
90Sr (Beta, 0.546 and 2.284 MeV)
Position: 16.9 mm, -21.1 mm
Original position (17.0 mm, -22.0 mm)
FWHM: 19.4 mm
Converter: none
Source to 1st DSSD distance: 26.5 mm
Source activity: 0.9 µCi
Measurement time: 30 min
Energy threshold: 1 MeV
21
2D image for beta point source
90Sr (Beta, 0.546 and 2.284 MeV)
Position: 0.5 mm, -17.8 mm
Original position (0.0 mm, -18.0 mm)
FWHM: 18.6 mm
Converter: none
Source to 1st DSSD distance: 26.5 mm
Source activity: 0.9 µCi
Measurement time: 30 min
Energy threshold: 1 MeV
22
Test results for gamma source
23
2D image for gamma point source
60Co (gamma, 1.173 and 1.332
MeV)
Position: -0.9 mm, -1.4 mm
Original position (-1.0 mm, -1.5 mm)
FWHM: 34.7 mm
Converter: Be 1.08 mm
Source to 1st DSSD distance: 30 mm
Source activity: 4.2 µCi
Measurement time: 30 min
Energy threshold: 0.1 MeV
24
2D image for gamma point source
60Co (gamma, 1.173 and 1.332
MeV)
Position: -17.9 mm, -16.5 mm
Original position (-18.0 mm, -17.0 mm)
FWHM: 35.1 mm
Converter: Be 1.08 mm
Source to 1st DSSD distance: 30 mm
Source activity: 4.2 µCi
Measurement time: 30 min
Energy threshold: 0.1 MeV
25
2D image for gamma point source
60Co (gamma, 1.173 and 1.332
MeV)
Position: -2.4 mm, -13.6 mm
Original position (-2.5 mm, -14.0 mm)
FWHM: 33.8 mm
Converter: Be 1.08 mm
Source to 1st DSSD distance: 30 mm
Source activity: 4.2 µCi
Measurement time: 30 min
Energy threshold: 0.1 MeV
26
Test results for high energy
gamma source
27
2D image for high energy gammas
Am-Be source (Gamma, 4.44
MeV)
Converter: Be 1.08 mm
Source to 1st DSSD distance: 45 mm
Source cup: 2.54 cm(outer diameter),
3.81 (length)
Source activity (4.44 MeV): 221.5 µCi
Measurement time: 30 min
Energy threshold: 1.5 MeV
28
2D image for high energy gammas
Am-Be source (Gamma, 4.44
MeV)
Converter: Be 1.08 mm
Source to 1st DSSD distance: 45 mm
Source cup: 2.54 cm(outer diameter),
3.81 (length)
Source activity (4.44 MeV): 221.5 µCi
Measurement time: 30 min
Energy threshold: 1.5 MeV
29
2D image for high energy gammas
Am-Be source (Gamma, 4.44
MeV)
Converter: Be 1.08 mm
Source to 1st DSSD distance: 45 mm
Source cup: 2.54 cm(outer diameter),
3.81 (length)
Source activity (4.44 MeV): 221.5 µCi
Measurement time: 30 min
Energy threshold: 1.5 MeV
30
Conclusion
In the present study, the prototype gamma
vertex imaging (GVI) system was constructed
and tested.
The developed prototype imaging system
shows satisfactory results for electron and
gamma sources.
The experiments using the therapeutic proton
beams will be performed in a near future.
Thank you for your attention