Development of an Absorbing Radio Frequency Shield for Safe Magnetic Resonance Imaging

In this dissertation, we propose a design for an absorbing radio frequency shield (ARFS) that helps to reduce the RF-induced heating effects at the tip of a deep brain stimulation (DBS) lead. We first review the transfer function method used to evaluate RF-induced temperature rise at a DBS lead tip, including both theory and measurements. Next, an ARFS shell is designed for a generic head-trunk human model for basic electromagnetic full-wave and thermal validations. A multi-layered ARFS shell structure is proposed, which consists of a highly conducting layer (HCL) embedded in a thick absorbing conductive layer (ACL) and an insulating layer. Furthermore, a similar ARFS shell is applied to an anatomically-correct human model with implanted DBS leads. The temperature rise at the lead tip is calculated and the shielding effectiveness of the proposed ARFS is analyzed. A total number of 297 lead-pathways are investigated. A head-only ARFS is also discussed for higher flexibility. Finally, the lead-tip temperature rise is measured inside a phantom for seven typical lead trajectories, in order to validate the methodology and the effectiveness of the proposed ARFS. The proposed ARFS structure is demonstrated to effectively reduce the temperature rise at the DBS lead tip for the trajectories studied in this dissertation. The average percentage reduction is 49.0% from the experimental results and 55.6% from the corresponding simulation results.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Electrical Engineering

Grantor

University of Houston

Year dc:date.issued

2017

Author dc:creator

• Li, Lintong

Advisor dc:contributor.advisor

• Chen, Ji

Committee members dc:contributor.committeemember

• Jackson, David R.
• Chen, Jiefu
• Benhaddou, Driss
• Zouridakis, George

• ARFS
• RF-induced heating
• Transfer function method
• DBS lead

Statement dc:rights

• The author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/10657/2877

OAI identifier oai:identifier

oai:uh-ir.tdl.org:10657/2877