Louisiana State University LSU Digital Commons LSU Master's Theses Graduate School 2002 Characterization of an in vivo diode dosimetry system for clinical use Kai Huang Louisiana State University and Agricultural and Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_theses Part of the Physical Sciences and Mathematics Commons Recommended Citation Huang, Kai, "Characterization of an in vivo diode dosimetry system for clinical use" (2002). LSU Master's Theses. 2765. https://digitalcommons.lsu.edu/gradschool_theses/2765 This Thesis is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Master's Theses by an authorized graduate school editor of LSU Digital Commons. For more information, please contact [email protected]. CHARACTERIZATION OF AN IN VIVO DIODE DOSIMETRY SYSTEM FOR CLINICAL USE A Thesis Submitted to Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the Requirements for the degree of Master of Science in The Department of Physics and Astronomy by Kai Huang B.S., Sichuan University, China, 1990 M.S., University of Miami, FL, 2000 December 2002 Acknowledgments To begin with, I am deeply grateful to my advisor, Dr. Oscar Hidalgo-Salvatierra, for the invaluable guidance and encouragement throughout the thesis project. I am especially grateful to Dr. William Bice without whose invaluable guidance and infinite discussions I would have been lost. I would like to express my sincere appreciation to the members of my thesis examining committee: Dr. M. L. Williams, Dr. E. Sajo, and Dr. S. Johnson for kindly agreeing to serve on my examining committee. I am deeply grateful to the professional and dedicated faculty of the Louisiana State University Nuclear Science Center for providing the foundation of knowledge necessary. I am deeply grateful to the entire staff at Mary Bird Perkins Cancer Center, especially the physicists, dosimetrists, and therapists for their guidance and contribution to my preparation for entering into the medical physics profession. Special thanks go to Dr. T. Kirby and Ms. A. Stam for their valuable guidance and support. Finally I am deeply grateful to the physicians at Mary Bird Perkins Cancer Center for the clinical knowledge they provided. ii Table of Contents ACKNOWLEDGMENTS .................................................................................................. ii LIST OF TABLES............................................................................................................. iv LIST OF FIGURES ............................................................................................................ v ABSTRACT.....................................................................................................................viii CHAPTER 1. INTRODUCTION ....................................................................................... 1 CHAPTER 2. LITERATURE REVIEW ............................................................................ 8 CHAPTER 3. MATERIALS AND METHODS .............................................................. 15 CHAPTER 4. RESULTS AND DISCUSSIONS ............................................................. 27 I. PHOTONS..................................................................................................................... 27 II. ELECTRONS............................................................................................................... 51 CHAPTER 5. SUMMARY AND CONCLUSION .......................................................... 58 REFERENCES ................................................................................................................. 62 APPENDIX A. 600C (BR, S/N 039) MEASUREMENTS .............................................. 65 APPENDIX B. 21EX (BR, S/N 1412) MEASUREMENTS............................................ 69 APPENDIX C. 21C (BR, S/N 090) MEASUREMENTS ................................................ 82 APPENDIX D. 21EX (COV, S/N 1251) MEASUREMENTS......................................... 91 APPENDIX E. 2000CR (HAM, S/N 951) MEASUREMENTS ...................................... 98 APPENDIX F. THE FORTRAN PROGRAM FOR CALCULATING DCF ................ 105 APPENDIX G. LAYOUT OF THE DIODE CALCULATION WORKSHEET [33] ... 118 VITA............................................................................................................................... 119 iii List of Tables Table 3.1 Linacs, modalities and energies at MBPCC. ................................................... 19 Table 3.2 Diode correction factors data collection table for open fields of photons, where 5 x 5 is the field size in cm2 , and 70 is the SSD in cm. ........................................... 20 Table 3.3 The field sizes used for wedged fields............................................................. 20 Table 3.4 Data collection table used for electrons, where 6x6 is the cone size in cm2 and 105 is the SSD in cm................................................................................................. 21 Table 4.1 Parameters for field size correction for each photon diode. ............................. 40 Table 4.2(a)(b)(c) Parameters for wedge correction for each photon diode..................... 41 Table 4.3 Coefficients of fitting polynomials for each photon diode............................... 43 Table 4.4 Parameters for field size correction for compiled 6MV and 18MV. ................ 43 Table 4.5(a)(b) Parameters for wedge correction for compiled 6MV and 18MV. ........... 44 Table 4.6 Coefficients of fitting polynomials for compiled 6MV and 18MV.................. 44 Table 4.7 Diode factors for each energy of each electron diode. ..................................... 56 Table 4.8 Coefficients of fitting polynomials for electrons.............................................. 57 iv List of Figures Figure 1.1 Sensitivity variation with pre-irradiation dose with 20 MeV electrons for an n type (•) and a p type (°) diode detector [3]................................................................. 5 Figure 2.1 Determination the exit calibration factor for the diode ..................................... 9 Figure 3.1 IVD Model 1131.............................................................................................. 15 Figure 3.2 QED diodes and Isorad-p diodes..................................................................... 16 Figure 4.1 Diode correction factors as a function of the source to surface distance, SSD, for entrance measurements. All data in this figure are for open fields with field size 10 x 10 cm2. .............................................................................................................. 27 Figure 4.2 DCF as a function of the field size, FS, for entrance measurements. All data in this figure are for open fields with SSD 100 cm....................................................... 28 Figure 4.3 DCF of 6MV QED diode of 20CR(Ham) as a function of the field size, FS, for entrance measurements. All data in this figure are for SSD 100 cm. ....................... 30 Figure 4.4 DCF of 18MV Isorad-p diode of 21C(BR) as a function of the field size, FS, for entrance measurements. All data in this figure are for SSD 100 cm. ................. 31 Figure 4.5 DCF as a function of the wedge angle for entrance measurements. All data in this figure are for SSD 100 cm and FS=10x10 cm2, and only for narrow and upper wedges....................................................................................................................... 31 Figure 4.6 Diode correction factors as a function of the SSD for entrance measurements. All data in this figure are for field size 10 x 10 cm2. (6MV QED photon diode of 20CR(Ham)). ............................................................................................................ 32 Figure 4.7 Diode correction factors as a function of the SSD for entrance measurements. All data in this figure are for field size 10 x 10 cm2. (15MV QED photon diode of 20CR(Ham)). ............................................................................................................ 32 Figure 4.8 Wedge factors for diode as a function of the SSD for entrance measurements. All data in this figure are for field size 10 x 10 cm2 (QED 6MV photon diode at 21EX(COV))............................................................................................................. 33 Figure 4.9 SSD dependence of QED 6MV photon diode of 21EX(COV) for different FSs (all for 60 degree wedged fields). ............................................................................. 34 Figure 4.10 FS dependence of QED 6MV photon diode of 21EX(COV) for different SSDs (all for 60 degree wedged fields). ................................................................... 34 v Figure 4.11 The SSD dependence for upper and lower wedged beams with 10x10 cm2 field size. The diode is 4MV QED photon diode at 21EX(BR). .............................. 36 Figure 4.12 The fitted curve and polynomial of 6MV QED diode at 600C(BR). ............ 37 Figure 4.13 The fitted curve and polynomial of 4MV QED diode at 21EX(BR). ........... 37 Figure 4.14 The fitted curve and polynomial of 10MV QED diode at 21EX(BR). ......... 38 Figure 4.15 The fitted curve and polynomial of 6MV Isorad-p diode at 21C(BR).......... 38 Figure 4.16 The fitted curve and polynomial of 18MV Isorad-p diode at 21C(BR)........ 38 Figure 4.17