Computational simulations of the influence of noise in optical CT reconstruction

In 3D radiation dosimetry with optical CT scanning readout, projections of transmitted light are recorded in either lines or planar. The projections are then transferred to optical density maps by use of filtered back-projection. Absolute dose maps can be derived from the optical density maps by calibration of the optical absorption coefficient to dose values. The transmission profiles will be subject to a certain level of detector noise and noise arriving from fluctuations in the light source. Different reconstruction filters in the frequency domain can be applied in the image reconstruction procedure. The noise level in the final reconstructed images is determined by the noise in the projections, the spatial resolution and the reconstruction algorithm. The reconstruction filters may also have an effect on the geometrical precision as a spatial frequency filter may also affect the spatial resolution. We here propose an easy method to assess both the noise sensitivity and the performance in terms of mapping dose distributions with various theoretical dose gradients.