Simulating noise in computed tomography reconstruction In the research of the computed tomography (CT) reconstruction, one needs to simulate the noise during CT projection and capturing. Then, my questions are:


How about the proper noise type? 
How to add the noise, in the sinogram domain or the frequency domain? 


Any reference materials are also preferred.
The easiest, and probably most straight forward way, seems to add the noise in the measurement domain, hence the sinogram.