Development of Data Acquisition Systems for Gamma Vertex

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

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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.

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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

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Proton beam

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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

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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)

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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

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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

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Development of multiplexing system

Board layout

Circuit design

Multiplexing system

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Amplification Shaping

amplifier

Multiplexing system

(P-side)

Multiplexing system

(N-side)

CR-110(P-side)

eV-5094(N-side)

Developed electronic read-out system

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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

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Developed prototype imaging system

1st DSSD

2nd DSSD

Electronic read-

out system for

DSSD

Beryllium

converter

Plastic

scintillation

detector

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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

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Test results

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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

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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

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Energy calibration using Compton edges

Y(channel) = 0.84 × X(energy) + 2.3

Adj. R-square = 0.998

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Test results for beta source

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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

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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

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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

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Test results for gamma source

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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

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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

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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

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Test results for high energy

gamma source

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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

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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

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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

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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