The cross-section of an X-ray phase shift image is a thousand times greater than that of X-ray attenuation in soft tissue over the diagnostic energy range implying phase imaging can achieve a much higher signal-to-noise ratio and substantially lower radiation dose than attenuation-based X-ray imaging. Grating interferometry is a state of the art X-ray imaging approach, which can simultaneously acquire information of X-ray phase-contrast, dark-field, and linear attenuation. This imaging modality can reveal subtle texture of tissues.
Time of flight PET (TOF-PET) is an advance over traditional PET that uses the time difference in detection of the two photon events. TOF information provides better localization of the annihilation event along the line formed by each detector pair, resulting in an overall improvement in signal to noise ratio (SNR) of the reconstructed image. This technology uses a direct estimation of the sinogram only from TOF PET data.