Applications of optics in PET : fast timing, multiplexing, and PET/MRI
Abstract/Contents
- Abstract
- This thesis presents the development and experimental evaluation of promising new PET (positron emission tomography) techniques which are made possible through the use of optical technologies. The large number of detector channels in modern PET scanners poses a challenge in terms of readout electronics complexity, and the preservation of fast timing information is especially important for time-of-flight (ToF) PET. A new multiplexing scheme based on encoding detector interaction events using a series of extremely fast overlapping optical pulses with precise delays has been developed. Encoding events in this way potentially allows many detector channels to be simultaneously encoded onto a single optical fiber that is then read out by a single digitizer. A two channel SiPM-based prototype utilizing this optical delay encoding technique along with a new circuit that implements dual threshold time-over-threshold is demonstrated. This prototype optical encoding and multiplexing system achieves a coincidence time resolution of 160 ps FWHM and an energy resolution of 13.1% FWHM at 511 keV with 3×3×5 mm³ LYSO crystals. All interaction information for both detectors, including timing, energy, and channel identification is encoded onto a single optical fiber with little degradation. Optical delay encoding and multiplexing technology could lead to ToF PET scanners with reduced electronics complexity and simplified data acquisition systems. Additionally, a brain sized RF (radio frequency)-penetrable PET insert has been designed for simultaneous operation within whole body MRI (magnetic resonance imaging) scanners. This system takes advantage of electro-optical coupling and battery power to enable the PET detector to electrically float relative to the MRI ground, permitting RF signals to be transmitted and received through the PET ring. The PET insert uses non-magnetic silicon photomultipliers (SiPMs) in conjunction with a compressed sensing signal multiplexing scheme and telecommunications lasers coupled to optical fibers to transmit analog PET detector signals out of the MRI room to a custom data acquisition system for decoding, processing, and reconstruction. The PET insert was placed within a 3T whole body MRI, and PET phantom images were successfully acquired under continuous pulsing from different MR imaging sequences. MR phantom images were successfully acquired from RF signals transmitted through the RF-penetrable PET ring using only the built in MR body coil, suggesting that simultaneous imaging is possible without significant mutual interference. These results show promise for this technology as an alternative to costly fully integrated PET/MR scanners, as a PET insert that is compatible with any existing clinical MRI system could greatly expand the availability of combined PET/MR. The performance of a commercial whole body ToF integrated PET/MR scanner was also evaluated.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2015 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Grant, Alexander M |
|---|---|
| Associated with | Stanford University, Department of Bioengineering. |
| Primary advisor | Levin, Craig |
| Thesis advisor | Levin, Craig |
| Thesis advisor | Graves, Edward (Edward Elliot), 1974- |
| Thesis advisor | Pelc, Norbert J |
| Advisor | Graves, Edward (Edward Elliot), 1974- |
| Advisor | Pelc, Norbert J |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Alexander M. Grant. |
|---|---|
| Note | Submitted to the Department of Bioengineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2015. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2015 by Alexander Michael Grant
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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