Technical Note: Nuclear imaging with an x-ray flat panel detector: A proof-of-concept study.

Purpose: Interventional procedures involving radionuclides (e.g., radioembolization) would benefit from single-photon emission computed tomography (SPECT) performed in the intervention room because the activity distribution could be immediately visualized. We believe it might be possible to perform SPECT with the C-arm cone beam computed tomography (CBCT) scanner present in the intervention room by equipping the x-ray flat panel detector with a collimator. The purpose of this study is to demonstrate the approach and to investigate the achievable SPECT reconstruction quality.

Methods: A proof-of-concept experiment was performed to evaluate the possibility of nuclear imaging with an x-ray flat panel detector. The experiment was digitally replicated to study the accuracy of the simulations. Three flat panel configurations (with standard hardware and reconstruction methodology, with sophisticated reconstruction methodology, and with expected future hardware) and a conventional gamma camera were evaluated. The Jaszczak and the NEMA IQ phantom (filled with Tc) were simulated and assessed on resolution and contrast-to-noise ratio (CNR).

Results: The proof-of-concept experiment demonstrated that nuclear images could be obtained from the flat panel detector. The simulation of the same configuration demonstrated that simulations could accurately predict the flat panel detector response. The CNR of the 37 mm sphere in the NEMA IQ phantom was 22.8 ± 1.2 for the gamma camera reconstructions, while it was 11.3 ± 0.7 for the standard flat panel detector. With sophisticated reconstruction methodology, the CNR improved to 13.5 ± 1.4. The CNR can be expected to advance to 18.1 ± 1.3 for future flat panel detectors.

Conclusions: The x-ray flat panel detector of a CBCT scanner might be used to perform nuclear imaging. The SPECT reconstruction quality will be lower than that achieved by a conventional gamma camera. The flat panel detector approach could, however, be useful in providing a cost-effective alternative to the purchase of a mobile SPECT scanner for enabling interventional scanning.