Title Page
Contents
ABSTRACT 22
CHAPTER I. INTRODUCTION 24
1.1. Beam Range Uncertainty in Proton Therapy 24
1.2. State-of-the-Art Methodology for Proton Beam Monitoring 29
1.2.1. Positron Emission Tomography Imaging 29
1.2.2. Prompt Gamma Imaging 30
1.2.3. Other Methods 36
1.3. Gamma Electron Vertex Imaging 38
1.4. Objectives and Scopes of This Study 41
CHAPTER II. DEVELOPMENT OF SIGNAL PROCESSING SYSTEM FOR COMPONENT DETCTOR 43
2.1. Component Detectors 44
2.1.1. Hodoscope: Double-sided Silicon Strip Detector 44
2.1.2. Calorimeter: EJ-200 Plastic Scintillation Detector 46
2.2. Signal Processing System 48
2.2.1. Signal Processing System: DSSD 48
2.2.2. Signal Processing System: Plastic Scintillation Detector 63
2.3. Detector Characterization 65
2.3.1. Energy Resolution of DSSD 65
2.3.2. Noise (Vrms) of DSSD(이미지참조) 72
2.3.3. Energy Calibration using Compton Edges for Plastic Scintillation Detector 78
2.3.4. Timing Resolution of Plastic Scintillation Detector 85
2.3.5. Timing Resolution of DSSD 88
2.4. P-/N-side Coincidence Measurement for Noise Reduction 92
CHAPTER III. PROOF-OF-PRINCIPLE OF GAMMA ELECTRON VERTEX IMAGING 96
3.1. Proof-of-Principe System for GEVI Method 97
3.1.1. Configuration of Imaging System 97
3.1.2. Coincidence System 100
3.1.3. Data Acquisition System and Image Reconstruction Program 102
3.1.4. Performance Estimation 106
3.2. 2D Imaging Measurements: Low Energy Gamma Source 111
3.3. 2D Imaging Measurements: High Energy Gamma Source 117
3.4. 2D Prompt Gamma Image Measurements for 45 MeV Proton Beam 122
3.5. 2D Prompt Gamma Measurements for Therapeutic Proton Beams 128
CHAPTER IV. DEVELOPMENT OF PROTOTYPE GAMMA ELECTRON VERTEX IMAGING (GEVI) SYSTEM 133
4.1. Field-of-view Extension of Imaging System 134
4.1.1. Configuration of DSSD Array 134
4.1.2. Configuration of Plastic Detector 136
4.1.3. Detector Characterization: Energy Resolution and Noise of DSSD 141
4.1.4. Detector Characterization: Energy Calibration of Plastic Detector 142
4.2. FPGA-based Fast DAQ System 144
4.2.1. Specification 144
4.2.2. Peak Detection Algorithm 147
4.2.3. Performance Test 150
4.3. Baseline Restorer 152
4.4. Coincidence System 157
4.5. Real-time Image Reconstruction Program 159
4.6. Mechanical Structure 161
CHAPTER V. IMAGING EXPERIMENTS FOR THERAPEUTIC PROTON BEAMS 163
5.1. Methodology for Determination of Distal Falloff Position 164
5.2. Prompt Gamma Measurement for Therapeutic Proton Beams 166
5.3. Consistency Study between Falloff Position and Beam Range 176
5.4. Imaging Experiments for variation of Incident Beam Position 182
CHAPTER VI. CONCLUSIONS AND FUTURE WORK 190
6.1. Summary and Conclusions 190
6.2. Suggestions for Future Work 194
REFERENCES 196
국문요지 200
Table 2.1. The Vrms values of the first DSSD (thickness: 145 ㎛)(이미지참조) 76
Table 2.2. The Vrms values of the second DSSD (thickness: 300 ㎛)(이미지참조) 77
Table 4.1. The geometric efficiency of the imaging system... 138
Table 5.1. The imaging sensitivity, the 50% distal falloff position, and its... 172
Table 5.2. The 50% distal falloff position and its uncertaingy of the prompt... 180
Table 5.3. The imaging sensitivity, the 50% distal falloff position, and its... 189
Fig. 1.1. Typical depth dose curve of mono-energetic proton beam... 26
Fig. 1.2. Variation in dose distribution of spread-out Bragg peak due to the beam... 27
Fig. 1.3. Typically applied range uncertainty margins to the prescribed range in... 28
Fig. 1.4. Relative production of the prompt gamma-ray as a function of proton... 33
Fig. 1.5. Energy spectrum of prompt gamma-rays generated by the proton... 34
Fig. 1.6. Cross sections of proton nuclear interactions with 16O (upper) and ¹²C (lower)...(이미지참조) 35
Fig. 1.7. The principle of the gamma electron vertex imaging (GEVI) for high... 40
Fig. 2.1. The double-sided silicon strip detector (DSSD) for tracking the... 45
Fig. 2.2. The EJ-200 plastic scintillation detector to determine the energy of the... 47
Fig. 2.3. The block diagram of the 16 channel signal processing system for one... 53
Fig. 2.4. The circuit diagram (a), the layout design (b), and the constructed PCB... 54
Fig. 2.5. The output signals (blue lines) from the shaping amplifier module with... 55
Fig. 2.6. Energy spectra of 137Cs (662 keV gamma-ray) source measured with the...(이미지참조) 56
Fig. 2.7. The block diagram of the multiplexing system to reduce the data... 57
Fig. 2.8. The circuit diagram (left) and the layout design (right) of the... 58
Fig. 2.9. The multiplexing system developed in the present study... 59
Fig. 2.10. Energy spectra of 137Cs (32 and 662 keV, 8.4 μCi), ¹³³Ba (31, 80 and...(이미지참조) 60
Fig. 2.11. The waveforms (upper) and histograms (lower) of the position signals... 61
Fig. 2.12. The signal processing system composed of the commercial preamplifier... 62
Fig. 2.13. The circuit diagram (a), the layout design (b), and the constructed PCB... 64
Fig. 2.14. Energy spectra of ²⁴¹Am (59.5 keV) source measured 66
Fig. 2.15. Energy spectra of 57Co (122.1 keV) source measured by the first DSSD...(이미지참조) 67
Fig. 2.16. Energy spectra of ¹³³Ba (31 keV) source measured by the first DSSD... 68
Fig. 2.17. Energy spectra of ²⁴¹Am (59.5 keV) source measured by the second... 69
Fig. 2.18. Energy spectra of 57Co (122.1 keV) source measured by the second...(이미지참조) 70
Fig. 2.19. Energy spectra of ¹³³Ba (31 keV) source measured by the second DSSD... 71
Fig. 2.20. Deposit energy of converted electrons in the 145 ㎛ (left) and 300 ㎛... 74
Fig. 2.21. LabVIEW-based Vrms calculation program to estimate the noise of...(이미지참조) 75
Fig. 2.22. The energy spectra of ²²Na (511 and 1275 keV) (a), 137Cs (662 keV)...(이미지참조) 81
Fig. 2.23. Energy spectra calculated by the Monte Carlo simulation and the... 82
Fig. 2.24. The energy calibration method applied in the present study. The... 83
Fig. 2.25. The correlation between the energy and the detector channel for... 84
Fig. 2.26. The experimental setup (upper) and black diagram (lower) of the... 86
Fig. 2.27. The time difference spectrum measured with the coincidence detection... 87
Fig. 2.28. The experimental setup (center) and block diagram of the electronic... 90
Fig. 2.29. The time difference spectra measured with the coincidence detection... 91
Fig. 2.30. The schematic diagram of the detection principle of the DSSD. When... 93
Fig. 2.31. Energy spectra of ¹³³Ba (31 keV) source measured with the first DSSD... 94
Fig. 2.32. Energy spectra of ¹³³Ba (31 keV) source measured by the second DSSD... 95
Fig. 3.1. The Beryllium plate for the conversion of the incident gammas to... 98
Fig. 3.2. The mechanical structure of the proof-of-principle GEVI system. To... 99
Fig. 3.3. The block diagram (a), the circuit diagram (b), the layout design (c), and... 101
Fig. 3.4. The data acquisition system for the proof-of-principle system. The... 104
Fig. 3.5. Customized program of 2D Image reconstruction for the proof-of-... 105
Fig. 3.6. The schematic diagram for the 2D image measurement of the beta... 108
Fig. 3.7. Deposited energy spectra of the electrons in the first (145 ㎛) and second... 109
Fig. 3.8. 2D images (upper) and projection distributions (lower) of 90Sr beta source with respect to...(이미지참조) 110
Fig. 3.9. The schematic diagram for the 2D image measurement of the gamma... 113
Fig. 3.10. Deposited energy spectra of the electrons in the first (145 ㎛) and... 114
Fig. 3.11. The measured 2D image (left) and calculated one (right) using the GEVI... 115
Fig. 3.12. Measured 2D images of 60Co gamma-ray source (1173 and 1332 keV)...(이미지참조) 116
Fig. 3.13. Energy level diagram of the 9Be(α,n)¹²C reaction in the...(이미지참조) 119
Fig. 3.14. 2D images obtained from the GEVI system for the Am-Be source (Eγ... 120
Fig. 3.15. Deposited energy spectra of the electrons in the first (145 ㎛) and... 121
Fig. 3.16. Experimental setup for the measurement of the prompt gamma... 125
Fig. 3.17. Prompt gamma distributions imaged by the proof-of-principle system... 126
Fig. 3.18. Longitudinal projection distributions imaged from the GEVI system... 127
Fig. 3.19. Experimental setup for the measurement of the prompt gamma... 131
Fig. 3.20. 2D images and longitudinal projection distributions of prompt gammas imaged by the GEVI system with... 132
Fig. 4.1. The configuration of the DSSD array. The active area of... 135
Fig. 4.2. The distributions of the geometric efficiency of the imaging system... 139
Fig. 4.3. The EJ200 plastic scintillation detector. The area of the scintillator... 140
Fig. 4.4. The correlation between the energy and the detector channel for Compton... 143
Fig. 4.5. The FPGA-based fast data acquisition system. The system consists of 16... 145
Fig. 4.6. The data acquisition program for the developed DAQ system 146
Fig. 4.7. Digitized signal at the input channel of the FPGA-based DAQ system for... 148
Fig. 4.8. The DSSD's position signals acquired by the FPGA-based DAQ system... 149
Fig. 4.9. Energy spectra of 137Cs (662 keV, activity: 8.18 μCi), ²²Na (511 and 1275...(이미지참조) 151
Fig. 4.10. The circuit diagram (a), the layout design (b), and the constructed PCB... 154
Fig. 4.11. The waveforms of output signals of the shaping... 155
Fig. 4.12. The signal amplitude variation with respect to the count rate for the... 156
Fig. 4.13. The block diagram (a), the circuit diagram (b), the layout design (c),... 158
Fig. 4.14. The real-time image reconstruction program using the MATLAB. 160
Fig. 4.15. The mechanical structure of the prototype GEVI system. To convert... 162
Fig. 5.1. Methodology for the determination of distal falloff region of prompt... 165
Fig. 5.2. Experimental setup for the measurement of prompt gamma distributions... 170
Fig. 5.3. 2D prompt gamma image and longitudinal projection distributions obtained by the prototype... 171
Fig. 5.4. Calculated and measured 2D prompt gamma images for 150 MeV proton... 173
Fig. 5.5. 2D prompt gamma images according to the number of protons of 150... 174
Fig. 5.6. Distal falloff position determined by the prototype imaging system for... 175
Fig. 5.7. Prompt gamma images for 126 (beam range: 116 ㎜), 132 (126 ㎜), 138 (136 ㎜), 144 (147 ㎜), 150... 179
Fig. 5.8. 50% distal falloff positions of measured prompt gamma distributions... 181
Fig. 5.9. Schematic diagram of experimental setup for 2D prompt gamma... 185
Fig. 5.10. 2D prompt gamma images obtained by the prototype system according... 186
Fig. 5.11. Distal falloff position of measured prompt gamma... 187
Fig. 5.12. 2D prompt gamma images obtained by the prototype system according to the vertical movement of incident... 188