The circle phantom

The development of reconstruction algorithms is greatly eased by using standard phantoms with know properties. The simplest possible phantom consists of a circle centered at the origo of the image. The projection of this phantom is readily understood, and it is suitable for the first testing of a reconstruction algorithm. An image of the phantom is shown below.

A Matlab function has been made that can generate projection data for this phantom. The file can be found at the ftp-server in the directory:

It is possible to generate images of different sizes and vary the number of projections generated. Instruction are found by writing help pht_circle at the Matlab prompt. The function can also easily be modified for generating off-centered circles and ellipses.