For processing and visualizing of CT and MRT images I often needed to read Dicom data. At the beginning I used a python Volume VOP in VTK to read the volumes but I was looking for a native Houdini way to do this.
Now I ended with a FBio definition which uses a standard windows installation of imagemagick (x64/16bit) and I have to admit it works like a charm.
Maybe someone could point me to a way to make these lines work in windows and in linux ..

# Dicom reading through imagemagick
#.dcm “convert %s /tmp/$$.hdr ; icp /tmp/$$.hdr stdout ; rm -f /tmp/$$.hdr” “icp stdin /tmp/$$.hdr ; convert /tmp/$$.hdr %s ; exec rm -f /tmp/$$.hdr”
.dcm “convert %s t:\Temp\$$.hdr ; icp t:\Temp\$$.hdr stdout ; rm -f t:\Temp\$$.hdr ” “”

# Jpeg2000 support through imagemagick
.jp2 “convert %s t:\Temp\$$.hdr ; icp t:\Temp\$$.hdr stdout ; rm -f t:\Temp\$$.hdr ” “”

just install imagemagick and append those lines to your FBIO file and have fun visualizing your dicom data.