View sampling requirements in fan beam computed tomography.

It is known that good CT reconstructions require that many views of the scanned object be obtained, where each view consists of many rays which traverse the patient. It is known that the required number of views depends on the diameter of the region reconstructed and the spatial resolution achieved. We present a new analysis of this question, valid for reconstruction from fan beam views, which shows that larger fan angles will require more views. Computer simulations, using a fan beam reconstruction algorithm, confirmed the predicted fan angle dependence and demonstrated that streak artifacts will result if too few views are used. The effect is also demonstrated experimentally by a phantom scan on a clinical CT scanner. Implications for clinical CT scanning are discussed.