  The primary objective is to enhance muon-tomographic image reconstruction
capability by providing distinctive information in terms of deciding on the
properties of regions or voxels within a probed volume "V" during any point of
scanning: threat type, non-threat type, or not-sufficient data. An algorithm
(MTclear) is being developed to ray-trace muon tracks and count how many
straight tracks are passing through a voxel. If a voxel "v" has sufficient
number of straight tracks (t), then "v" is a non-threat type voxel, unless
there are sufficient number of scattering points (p) in "v" that will make it a
threat-type voxel. The algorithm also keeps track of voxels for which not
enough information is known: where p and v both fall below their respective
threshold parameters. We present preliminary results showing how the algorithm
works on data collected with a Muon Tomography station based on gas electron
multipliers operated by our group. The MTclear algorithm provides more
comprehensive information to a human operator or to a decision algorithm than
that provided by conventional muon-tomographic reconstruction algorithms, in
terms of qualitatively determining the threat possibility from a probed volume.
This is quite important because only low numbers of cosmic ray source muons are
typically available in nature for tomography, while a quick determination of
threats is essential.
