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A Robotic Multi-Pinhole SPECT System for Onboard and Other Region-Of-Interest Imaging


J Bowsher

J Bowsher*, S Yan, J Roper, W Giles, F Yin, Duke University, Durham, NC

TU-A-BRA-1 Tuesday 8:00:00 AM - 9:55:00 AM Room: Ballroom A

Purpose: Radiation therapy beam guidance and modulation at treatment time could be substantially supported by onboard molecular and functional imaging capability. Currently there is very little range of technology available for this. Herein we propose and investigate a robotic multi-pinhole SPECT system for this purpose.

Methods: A 49-pinhole system is designed with 7 pods and 7 pinholes per pod. Pod geometry is such that the full target region-of-interest (ROI) is within the FOV of all 7 pinholes for all pod distances exceeding a minimum distance from the ROI. Motion of the pods relative to one another can involve just 1 or 2 degrees of freedom per pod. Motion of the entire, composite 49-pinhole system is provided by a robot. This design enables all 49 pinholes to view the full ROI throughout detector trajectories that can achieve sampling objectives, e.g. on line integrals measured, while also providing good resolution and sensitivity via close proximity to the ROI. The design is evaluated through computer simulation studies in which 7 and 10 mm diameter structures of 6-to-1 radiotracer uptake are added to the XCAT phantom. Results are compared to imaging with a compact parallel-hole collimated detector, which is utilized as a reference for conventional SPECT imaging configurations.

Results: For the 7 cm-diameter target region of interest, the 49-pinhole system shows markedly improved imaging as compared to the reference, parallel-hole collimated detector. Most 7 mm and 10 mm diameter structures are readily visualized with 4 minute scans.

Conclusions: In only a few minutes of scan time, the designed multi-pinhole SPECT system can provide molecular and functional information about the target region as patients are in position for radiation therapy.

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