Optically controlled magnetic resonance imaging compatible active needle
Abstract/Contents
- Abstract
- An active needle is proposed for the development of magnetic resonance imaging (MRI) guided percutaneous procedures. The needle uses internal laser heating, conducted via optical fibers, of a shape memory alloy (SMA) actuator to produce bending in the distal section of the needle. Active bending of the needle as it is inserted into an organ allows it to reach small targets while overcoming the effects of interactions with surrounding tissue, which can otherwise deflect the needle away from its ideal path. The active section is designed to bend preferentially in one direction under actuation, and is made from SMA for its combination of MR- and bio-compatibility and its superelastic bending properties. A prototype, with a size equivalent to a standard 16 gauge biopsy needle, exhibits significant bending in the air with a tip rotation of more than 10 degree. For this slender, 1.67 mm diameter, MR-compatible active needle, a distributed, side optical actuation method is presented. A prototype, with multiple side heating regions made by chemical etching, demonstrates faster initial response than prototypes that use fiber tip heating for a given optical power. A gold coating captures light that would otherwise be lost and redirects it back to the SMA wire for higher efficiency and greater safety in tissue. A single-ended optical sensor with a gold reflector at the tip is also developed to measure the curvature independently of temperature as a function of optical transmission loss. Preliminary tests with the sensor prototype demonstrate approximately linear response and a repeatable signal, independent of the bending history. The optical sensor is intended for closed-loop control of the bend angle, using a presented opto-thermo-mechanical model. The needle performance was studied in tissue phantoms mimicking human prostate. The experimental results show that this needle can compensate for the usual targeting error during prostate biopsy. For future versions, a more flexible needle design is suggested to increase the steerability and bending speed. In addition, because human tissue works as a large heat sink, resulting in fast heat dissipation from the wire, it is suggested to use a wire with a lower transition temperature. Ideally, the wire should have a transition temperature starting only slightly above body temperature. This modification would also reduce the required optical power. A feasibility study of the fabrication of such a wire is presented, combining the standard annealing technique for coarse tuning with pre-stressing for fine tuning of the transition temperature.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2012; 2013 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Ryu, Seok Chang |
|---|---|
| Associated with | Stanford University, Department of Mechanical Engineering |
| Primary advisor | Cutkosky, Mark R |
| Thesis advisor | Cutkosky, Mark R |
| Thesis advisor | Daniel, Bruce (Bruce Lewis) |
| Thesis advisor | Okamura, Allison |
| Advisor | Daniel, Bruce (Bruce Lewis) |
| Advisor | Okamura, Allison |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Seok Chang Ryu. |
|---|---|
| Note | Submitted to the Department of Mechanical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2012. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2012 by Seok Chang Ryu
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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