NOISE REDUCTION IN LOW-DOSE COMPUTER TOMOGRAPHY

摘要

1. A system comprising: a source that rotates around the examination area and emits radiation that crosses the examination area; a radiation-sensitive detector matrix that detects radiation crossing the examination area and generates projection data indicative of the detected radiation; and a noise reduction device in the projection data that reduces the noise level in the projection data, wherein the noise reduction device reduces the noise level in the projection based on the number of detected photons for the projection. 2. The system of claim 1, wherein the noise reduction apparatus comprises: a photon estimator that estimates the number of detected photons for each projection, wherein the noise reduction apparatus in the projection data reduces the noise level in the projection data based on the estimated number of detected photons. The system of claim 2, wherein the estimated number of detected photons is a smoothed moving average of the estimated number of detected photons. The system of claim 1, wherein the noise reduction device in the projection data further comprises: a noise reduction device that reduces noise in the projections based on minimizing a cost function including at least two members, a first member of the total variation and the second term of the weighted least squares, and the estimated number of detected photons. 5. The system of claim 1, wherein the noise reduction device in the projection data further comprises: a noise reduction device that reduces the noise level in the projection by giving preference�