Notations
| g | Vector of projection data |
| f | Vector of image data |
| A | Matrix such that g = Af |
| aij | Value of element located at ith row and jth column of matrix A |
| i | Projection subscript |
| j | Pixel subscript |
| gi | Number of counts in ith bin of a projection dataset |
| ḡi | Mean value of gi, assuming gi is a Poisson random variable |
| fj | Number of disintegrations in jth pixel of a slice |
| f̄j | Mean value of fj assuming fj is a Poisson random variable |
| m | Number of pixels |
| n | Number of bins |