Development of Data Acquisition Systems for Gamma Vertex Imaging System for Proton Dose Verification

Development of Data Acquisition Systems for Gamma Vertex Imaging System for Proton Dose Verification Han Rim Lee 1, Jong Hoon Park 1, Young-su Kim 1, Won Gyun Jung 2, Chan Hyeong Kim 1 1 Department of Nuclear Engineering, Hanyang University 2 Heavy-ion Clinical Research Division, Korean Institute of Radiological & Medical Sciences 53 rd Annual Conference of the Particle Therapy Co-Operative Group

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. 2

Performance estimation with Geant4 simulation Simulation condition Primary particles: 1.2 10 9 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 Geant4 simulation Proton beam 3

Proton beam 4

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 V rms 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 5

Hodoscope (double-sided silicon strip detector) Hodoscope Hodoscope e e e Calorimeter Source Electron converter Double-sided silicon strip detector (DSSD) Specification of DSSD - Detector type: W1-type (Micron Semiconductor Ltd., UK) - Active area: 5 5 cm 2 - Strip number: 16 for each side (strip pitch: 3.125 mm) - Detector thickness: 1 st DSSD (145 μm), 2 nd DSSD (300 μm) - Bias voltage: 20 V (145 μm), 30 V (300 μm) 6

Electronic read-out system for hodoscope (DSSD) DSSD signal (16 ch) CSP Slow amplifier Multiplexer Energy DAC Position Fast amplifier LED CR-110 (Cremat Inc., MA) for p-side ev-5094 (ev products, PA) for n-side Primary encoder In-house system 7

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 Circuit design Shaping amplifier Board layout 8

Development of multiplexing system Circuit design Multiplexing system Board layout 9

Developed electronic read-out system Amplification Shaping amplifier CR-110(P-side) Multiplexing system (P-side) ev-5094(n-side) Multiplexing system (N-side) 10

Electronic read-out system for calorimeter (plastic scintillation detector) 1 st DSSD 2 nd DSSD e e e Calorimeter Source Electron converter SCIONIX(NL) Scintillator: EJ200 (thickness: 2cm, Eljen technology) Photomultiplier (9102, ET Enterprises Ltd) - Quantum eff. : 28% @ 400 nm - Gain: 2 10 4 @ 750 V Voltage divider Preamplifier (AMP-1000 Preamplifier) - Pulse fall time: ~ 50 µs - Maximum signal height: ±10 V Amplifier (in-house shaper, 250 ns) 11

Developed prototype imaging system Beryllium converter 1 st DSSD Electronic readout system for DSSD 2 nd DSSD Plastic scintillation detector 12

DAQ and image reconstruction system PXI based data acquisition system Data analysis and image reconstruction system 1. Digitizer control and data acquisition 2. Determination of energy and time 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 3. Check time and energy window 4. Image reconstruction 13

Test results 14

Performance test: energy resolution of hodoscopes 241 Am (59.5 kev) 57 Co (122 kev) First DSSD (145 μm) P-side 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) 15

Performance test: V rms of DSSD First DSSD (145 μm) P-side V rms (V) V rms (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 N-side V rms (V) V rms (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 Second DSSD (300 μm) P-side V rms (V) V rms (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 N-side V rms (V) V rms (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 3.50 ± 0.44 kev 4.05 ± 0.48 kev 4.49 ± 0.17 kev 5.73 ± 0.20 kev Minimum energy deposition of Compton electron to DSSD - First DSSD: 50.68 kev - Second DSSD: 104.85 kev 16

Energy calibration using Compton edges Y(channel) = 0.84 X(energy) + 2.3 Adj. R-square = 0.998 17

Test results for beta source 18

2D image for beta point source 90 Sr (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 1 st DSSD distance: 26.5 mm Source activity: 0.9 µci Measurement time: 30 min Energy threshold: 1 MeV 19

Test results for gamma source 22

2D image for gamma point source 60 Co (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 1 st DSSD distance: 30 mm Source activity: 4.2 µci Measurement time: 30 min Energy threshold: 0.1 MeV 23

Test results for high energy gamma source 26

2D image for high energy gammas Am-Be source (Gamma, 4.44 MeV) Converter: Be 1.08 mm Source to 1 st 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 27

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. 30

Thank you for your attention