A high-resolution head insert device for a clinical PET/CT scanner

Abstract

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Objectives: To develop a prototype PET insert device that can be attached to a clinical PET/CT scanner to improve resolution of head and neck images.

Methods: The device consists of 28 detector modules arranged into 2 half-rings. Each detector consists of 13x13 LSO crystals (2x2x5 mm³ each), a custom light guide, and a multi-channel PMT. The device can be precisely positioned in the gantry opening or completely retracted via a 3D positioning system. Signals from the insert are fed to scanner electronics through 7 active switch boards that select between scanner detectors and insert detectors. Coincidence events between the insert and the scanner can be extracted from the list mode data. A maximum-likelihood expectation-maximization algorithm combines coincidence events between all detectors to jointly estimate the images. Initial tests were focused on the compatibility of insert detector and system electronics, functionality of the switch board, and correctness of image reconstruction algorithm.

Results: Insert detectors are compatible with scanner electronics except that its signal arrives 10 ns ahead of scanner detectors. With 1.8-meter long cables connecting the insert to the scanner, the signals are now synchronized. The switch boards properly select and transmit the signals without distortion. Image reconstruction algorithm is fully tested using data from an animal PET insert device. Construction of the head insert device is complete, while the positioning system is being finished.

Conclusions: Functionality of individual components has been fully validated. Evaluation of the full system is being conducted. Initial images will be presented. The device is expected to provide higher resolution PET images for head and neck imaging applications.

Research Support: NIH (CA110011) and Susan G. Komen for the Cure (BCTR0601279)