Collimator-based Coincidence Imaging for Double Photon Emitting Nuclides

We have proposed a new concept of time/position correlation type tomographic method based on a directionality-sensitive gamma camera, which can identify incident γ-ray direction. This method utilizes the correlation between two γ-ray photons and provides the radioactivity concentration in the body with a high resolution and a high signal-to-noise ratio. 111In is known as a cascade γ-ray emitting nuclide. Besides 111In, we have explored new candidates and found some other nuclides with different lifetimes. A focused lead collimator was designed and coupled to a pixelated detector array for this new coincidence imaging modality. The method shows a significant background rejection and an improved spatial resolution in comparison with the single-photon analysis.