this directory has various data files used in the examples,
including George Zubal's phantom from http://noodle.med.yale.edu/zubal/

and one slice of the NCAT phantom from UNC (or maybe now JHU)
ncat,256,slice,140,ct,dens.fld
see:
@a segars:02:sot ieee-t-ns 49 3 675-679 jun 2002
W P Segars  B M W Tsui
Study of the efficacy of respiratory gating in myocardial SPECT using the new 4-D NCAT phantom

and a T1 weighted image from the brainweb site
http://www.bic.mni.mcgill.ca/cgi/brainweb1
