Poster - Thur Eve - 14: The effect of fluence and detector size on image quality in multi-projection compton scatter...

To assess how radiation dose and size of energy sensitive detectors affects image quality in multi-projection Compton scatter tomography.

A Compton scatter tomography system was simulated in Maltab. The system consists of a point source generated x-ray fan beam and energy sensitive photon counting detectors, placed along a line with the source outside the periphery of the primary beam. Single scattered photons from a low contrast phantom simulating breast tissues were simulated. Simulation parameters are dose-limited and closely matched to typical breast CT. Poisson distributed noise was added to simulate quantum noise.

We have successfully reconstructed electron density images in a clinical fan-beam breast CT system, in the presence of noise. The reconstruction illustrates accurate spatial alignment of the structures of interest in the phantom. The increase in MSE due to noise was ∼11%. The optimal detector size of 2 × 2 mm² is a trade off between the increased noise, that is present when smaller detector sizes are used, and the blurring of the image that occurs as larger detectors are employed.

For breast CT dose of 4-12 mGy, the optimal detector size for a Compton scatter reconstruction using 360 projections and 1000 eV energy resolution was found to be 2 × 2 mm² . The ability to visualize large low contrast (9%) and small (2 mm diameter) high contrast objects was demonstrated.