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

  • Monte-Carlo
  • Linac-MR
  • Skin Dose

• Graduation date

  Spring 2013

• 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.