Purpose: To validate a dual readout, scintillating fiber-based non-invasive positron detector, hereinafter called NID, developed to determine the arterial input function (AIF) for dynamic positron emission tomography against a previously validated microfluidic positron detector.
Methods: The NID consists of a plastic scintillating fiber with each end coupled to optical fiber cables for scintillation light transmission. The optical fiber cables are connected to photomultiplier tubes in a dual readout setup. The scintillating fiber is enclosed inside a plastic cylindrical shell, placed in a light-tight box. A polyethylene phantom is constructed to simulate a patientâ€™s wrist, with drilled radial artery and placed in the shell. . For the performed measurements, a closed loop system was created using a polyethylene tube through the NID, the microfluidic detector, a pump and liquid reservoir. Each scan started with 30 seconds of water circulation followed by an almost instant tracer injection. Two minutes after the radiotracer injection, 6 mL of water over one minute was added. Total scan duration was 10 minutes. Six scans were performed, one set with clinically relevant concentrations and another below clinically relevant concentrations for 18F, 11C and 68Ga. The high concentrations were 5.6, 13.4 and 10.3 MBq/mL respectively. The low concentrations were 2.0, 1.9 and 1.5 MBq/mL respectively. The data was normalized to the output of the microfluidic detector.
Results: The clinically relevant scans show a good agreement between the two detectors. The signal to noise ratio (SNR) for 18F, 11C and 68Ga were 5.16, 22.16 and 15.38 respectively. At high concentrations, the NID is capable of accurately detecting activity concentration changes in the system.
Conclusion: At clinically relevant concentration levels and using a phantom model, the NID provided a good SNR and agreed with the microfluidic detector using three radionuclides showing that it could be suitable for clinical use.
Funding Support, Disclosures, and Conflict of Interest: This work was supported by the Collaborative Health Research Projects (grant #523394-18), and Natural Sciences and Engineering Research Council (grant #241018) and CFI JELF (grant #34987)..