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Generation and Modeling of Radiation for Clinical and Research Applications Bishwambhar Sengupta Clemson University, [email protected]

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Generation and Modeling of Radiation for Clinical and Research Applications Bishwambhar Sengupta Clemson University, Bishwambharsengupta@Gmail.Com Clemson University TigerPrints All Dissertations Dissertations 8-2019 Generation and Modeling of Radiation for Clinical and Research Applications Bishwambhar Sengupta Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_dissertations Recommended Citation Sengupta, Bishwambhar, "Generation and Modeling of Radiation for Clinical and Research Applications" (2019). All Dissertations. 2440. https://tigerprints.clemson.edu/all_dissertations/2440 This Dissertation is brought to you for free and open access by the Dissertations at TigerPrints. It has been accepted for inclusion in All Dissertations by an authorized administrator of TigerPrints. For more information, please contact [email protected]. Generation and Modeling of Radiation for Clinical and Research Applications A Dissertation Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Physics by Bishwambhar Sengupta August 2019 Accepted by: Dr. Endre Takacs, Committee Chair Dr. Delphine Dean Dr. Brian Dean Dr. Jian He Abstract Cancer is one of the leading causes of death in todays world and also accounts for a major share of healthcare expenses for any country. Our research goals are to help create a device which has improved accuracy and treatment times that will alleviate the resource strain currently faced by the healthcare community and to shed some light on the elementary nature of the interaction between ionizing radiation and living cells. Stereotactic radiosurgery is the treatment of cases in intracranial locations using external radiation beams. There are several devices that can perform radiosurgery, but the Rotating Gamma System is relatively new and has not been extensively studied. It has much flexibility as it uses fewer radiation sources which are capable of moving around the patient, unlike other systems that employ virtually static sources. We propose two new working modes of the RGS that will enable it to further extend its operational capabilities. We have studied the operation of an RGS device at the Rotating Gamma Institute in Debrecen, Hungary and have developed a Monte Carlo model of the same. The simulation results of the normal modes of operation are in close agreement with clinical results, thus validating our model. We have then used this model to propose the Intensity Modulated Radiosurgery (IMRS) and the Speed Modulated Radiosurgery (SMRS) mode of the RGS. In both modes, we can see that the penumbra falls off sharply along one axis which is required for treating cases near critical organs. While the IMRS has a disadvantage of longer treatment times, it is absent from the SMRS mode. Current governing bodies state that any amount of radiation, with no threshold amount, is harmful and must be avoided at any cost. While this assumption is safe for radiation safety considerations, there is growing scientific evidence that the situation is more complex at low doses. In the modern day, we are continually exposed to low-dose radiation. Diagnostic imaging is one of the major contributors for exposure to low-dose ionizing radiation with over 70 million scans ii performed annually in the US. This calls for the study of the effect that low-dose radiation has on cells. The scientific community is currently divided on the effect that low-dose radiation has on living cells as experiments have not been able to provide conclusive results. We have designed an incubator cabinet which allows the study of the effect of low-dose x-ray radiation on cells in a temperature- and atmospheric-composition-controlled, radiation-safe environment. We use bremsstrahlung radiation to excite quasi-monochromatic, fluorescent x-rays of a metal plate to act as a source that is used to irradiate biological samples. We have also installed a photon-counting detector to characterize the radiation incident on the cell cultures. By changing the tube current or by switching out the metal plates we are able to effectively change the dose rate, and the energy of the radiation, giving us the control to perform different experiments. Here, we have presented our device along with calculations that prove the capabilities of our device. We hope that future research will shine some light through the fog that currently engulfs radio-biology research in this radiation regime. iii Dedication I would like to dedicate this work to my family; Ma, Baba and Madhu. iv Acknowledgments I would like to start by thanking my advisor Dr. Endre Takacs. When I joined Dr. Takacss lab in the summer of 2016 I did not have much idea about Medical Physics. Yet, he accepted me as his Ph.D. student and has nurtured me into what I am today. I thank him for his patience as I stumbled through my research, for his kind encouragement and for his belief in me that I could succeed in my graduate career. Also for giving me the freedom to pursue projects in my way and for granting me several opportunities to explore new avenues in research. I have learned from him, both academic and life-lessons that would be valuable throughout my life. I also thank him for giving me the freedom to pursue my non-academic interests at Clemson. These activities have been my refuge from and helped me survive the grad school grind. Thank you, Dr. Takacs, for ensuring that I have a positive grad school experience. I wish to express my gratitude to my Ph.D. committee members, Dr. Delphine Dean, Dr. Jian He, and Dr. Brian Dean. Thank you for your support and advice throughout my Ph.D. and for spending so many of your valued hours on my work and for providing counsel for my research career. You always made yourself available whenever I knocked on your door with any questions for which I shall remain forever grateful. Many thanks to the Department of Physics and Astronomy and Clemson University for providing numerous grants for travelling to professional conferences and workshops. Attending these meetings have exposed me to my peers working in this field and has helped build my professional network. A special shout out to Dr. Daniel Thompson for being a great supervisor and for working with the TA's schedule in mind. Thank you for looking out for us. I am grateful for the help and support from my lab mates: Leon Zheng, Donald Medlin, Justin Napolitano and Jaclyn D'Avanzo for making my experience at Clemson something that I will fondly remember forever. Thank you for volunteering to go through my work and screening for v errors, for the numerous questions that helped in my better understanding of the subject and most importantly, thank you for your friendship. It was a great experience working beside you and I wish you all the best and know that you will do well. I would also like to thank the team at Medikai Innovacio Kft, especially David, Peter, and Tibor for their support and contribution towards this project. Thank you Dr. Filep for being a great mentor and for showing me around Debrecen. It was great chatting with you after work and thank you for sharing your experiences. I would also like to thank Laszlo Gulyas and Tamas Hollo from the Rotating Gamma Institute. Thank you for patiently answering my barrage of questions and for sharing your experiences working on the RGS. I could not have completed the project without your help and contribution. I had a great time working with yall. K¨osz¨on¨om!I would also like to thank Dr. Josef Dobai and Dr. Imre Fedorcsak for sharing their clinical experiences with me and for being available to answer several of my questions. I am highly obliged to Mr. Dan Pass of Moxtek Inc., for providing the experimental tube. Without your help, this project would not have been possible. I would also like to thank Shawn Chin for providing technical support for the detector and the tube from Moxtek. I would like to thank my friends Mihiri, Abhishek, Puspal, Arghya, Kanishka and Samalka for their love and support and especially for enduring through my physics jokes and for helping in preserving my sanity. A special thanks to Paryatan Mandali for being there and making things happen and for the pearls of wisdom from Dr. Paliya which were really helpful. Thank you, Wren, for introducing me to Bojangles and many other important things in life. Thank you, Ethan, Andy, Chris, Amy, Yongchang, Yunhui, Gezhou, Fanchen, Yamei, Matt and Andrew for making the initial years and 310 more bearable. Lastly and most importantly I would like to thank my family for their love, support, and understanding. To my parents, without your encouragement, it would not have been possible to come this far. Thank you for nurturing my curiosity and for giving me your blessings to pursue the path less traveled. To Madhu, for being the best sister and my biggest fan. Thank you! vi Table of Contents Title Page ............................................ i Abstract ............................................. ii Abstract ............................................. ii Dedication............................................ iv Dedication............................................ iv Acknowledgments ....................................... v List of Tables ..........................................viii List of Figures.......................................... ix 1 Introduction......................................... 1 1.1 Cancer: Cells with Super Powers? ............................ 2 1.2 Research Objectives .................................... 7 2 The Physics of Radiation ................................. 9 2.1 Electromagnetic
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