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Skin Dose in Longitudinal and Transverse Linac-MRIs using Monte-Carlo and realistic 3D MRI field models

  • Author / Creator
    Keyvanloo Shahrestanaky, Amirmohamad
  • The integration of a clinical linear accelerator (linac) with a magnetic resonance imaging (MRI) system would provide real-time tumor tracking. The magnetic fields of linac-MR systems modify the path of contaminant electrons in photon beams, which alters patient skin dose. In this work, we used Monte Carlo calculations that incorporate realistic 3D magnetic field models of longitudinal and transverse linac-MR systems to accurately quantify the changes in skin dose. The results show that fringe fields of realistic 3D B-fields decay rapidly and have a very small magnitude at the linac’s head. As a result, for longitudinal linac-MR systems only a small increase in the entrance skin dose is predicted. For transverse linac-MR systems, changes to the entrance skin dose are small for most scenarios. On the exit side, however, a fairly large increase is observed for perpendicular beams due to the electron return effect, but significantly drops for large oblique angles of incidence.

  • Subjects / Keywords
  • Graduation date
    2013-06
  • Type of Item
    Thesis
  • Degree
    Master of Science
  • DOI
    https://doi.org/10.7939/R38W22
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
    English
  • Institution
    University of Alberta
  • Degree level
    Master's
  • Department
    • Department of Oncology
  • Specialization
    • Medical Physics
  • Supervisor / co-supervisor and their department(s)
    • Dr. Warkentin, Brad (Oncology-medical Physics)
    • Dr. B. Falllone, Gino (Oncology-medical Physics)
  • Examining committee members and their departments
    • Dr. Warkentin, Brad (Oncology-medical Physics)
    • Dr. Marchand, Richard (Physics)
    • Dr. Rathee, Satyapal (Oncology-medical Physics)
    • Dr. B. Falllone, Gino (Oncology-medical Physics)