A technique for dose reduction using prior image constrained compressed sensing (DR-PICCS) in computed
tomography (CT) is proposed in this work. In DR-PICCS, a standard FBP reconstructed image is forward
projected to get a fully sampled projection data set. Meanwhile, it is low-pass filtered and used as the prior
image in the PICCS reconstruction framework. Next, the prior image and the forward projection data are
used together by the PICCS algorithm to obtain a low noise DR-PICCS reconstruction, which maintains the
spatial resolution of the original FBP images. The spatial resolution of DR-PICCS was studied using a Catphan
phantom by MTF measurement. The noise reduction factor, CT number change and noise texture were studied
using human subject data consisting of 20 CT colonography exams performed under an IRB-approved protocol.
In each human subject study, six ROIs (two soft tissue, two colonic air columns, and two subcutaneous fat)
were selected for the CT number and noise measurements study. Skewness and kurtosis were used as figures of
merit to indicate the noise texture. A Bland-Altman analysis was performed to study the accuracy of the CT
number. The results showed that, compared with FBP reconstructions, the MTF curve shows very little change
in DR-PICCS reconstructions, spatial resolution loss is less than 0.1 lp/cm, and the noise standard deviation
can be reduced by a factor of 3 with DR-PICCS. The CT numbers in FBP and DR-PICCS reconstructions agree
well, which indicates that DR-PICCS does not change CT numbers. The noise textures indicators measured
from DR-PICCS images are in a similar range as FBP images.