Abstract
One challenge for PET-MR hybrid imaging is the correction for attenuation of the 511 keV annihilation radiation by the required RF transmit and/or RF receive coils. Although there are strategies for building PET transparent Tx/Rx coils, such optimised coils still cause significant attenuation of the annihilation radiation leading to artefacts and biases in the reconstructed activity concentrations. We present a straightforward method to measure the attenuation of Tx/ Rx coils in simultaneous MR-PET imaging based on the natural Lu-176 background contained in the scintillator of the PET detector without the requirement of an external CT scanner or PET scanner with transmission source. The method was evaluated on a prototype 3T MR-BrainPET produced by Siemens Healthcare GmbH, both with phantom studies and with true emission images from patient/ volunteer examinations. Furthermore, the count rate stability of the PET scanner and the x-ray properties of the Tx/Rx head coil were investigated. Even without energy extrapolation from the two dominan gamma energies of Lu-176 to 511 keV, the presented method for attenuation correction, based on the measurement of Lu-176 background attenuation, shows slightly better performance than the coil attenuation correction currently used. The coil attenuation correction currently used is based on an external transmission scan with rotating Ge-68 sources acquired on a Siemens ECAT HR + PET scanner. However, the main advantage of the presented approach is its straightforwardness and ready availability without the need for additional accessories.
Original language | English |
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Article number | 035039 |
Number of pages | 16 |
Journal | Physics in Medicine and Biology |
Volume | 63 |
Issue number | 3 |
DOIs | |
Publication status | Published - 6 Feb 2018 |
Externally published | Yes |
Keywords
- 3D PET
- COMPATIBILITY
- INSERT
- Lu-176 background
- MR-PET
- PET/MRI SYSTEMS
- POSITRON-EMISSION-TOMOGRAPHY
- QUANTIFICATION
- SCANNER
- SURFACE COILS
- TIME-OF-FLIGHT
- TRANSMISSION
- Tx/Rx coil
- attenuation correction