A method of security inspection by a security inspection system comprising ultra-wideband transmitters and receivers , the method comprising: scanning a walk-through inspection space along with an inspected person passing there through to yield collected data informative of scattered signals in association with respective channels, each channel characterized by the respective ultra-wideband transmitter, receiver and their polarization states, wherein the ultra-wideband transmitters and receivers are arranged at both sides of the inspection space; upon dividing the inspection space into a plurality of subspaces such that each voxel in the inspection space belongs to one and only one subspace , providing image reconstruction separately for each subspace of the plurality of the subspaces , wherein image reconstruction for voxels residing in a given subspace is provided using collected data corresponding to a set of channels selected for the given subspace in accordance with predefined rules; and using image reconstruction results to detect a concealed object; further comprising, for each given subspace: calculating one or more parameters of specular points of channels reflected by a virtual equi-area tessellated sphere co-centric with a given subspace ; identifying channels with the calculated one or more parameters matching channel-dropping criteria defined to the given subspace thereby giving rise to omitted channels ; and generating a set of channels selected for the given subspace, the generating comprising excluding the omitted channels from further processing for image reconstruction . scanning a walk-through inspection space along with an inspected person passing there through to yield collected data informative of scattered signals in association with respective channels, each channel characterized by the respective ultra-wideband transmitter, receiver and their polarization states, wherein the ultra-wideband transmitters and receivers are arranged at both sides of the inspection space; upon dividing the inspection space into a plurality of subspaces such that each voxel in the inspection space belongs to one and only one subspace , providing image reconstruction separately for each subspace of the plurality of the subspaces , wherein image reconstruction for voxels residing in a given subspace is provided using collected data corresponding to a set of channels selected for the given subspace in accordance with predefined rules; and using image reconstruction results to detect a concealed object; further comprising, for each given subspace: calculating one or more parameters of specular points of channels reflected by a virtual equi-area tessellated sphere co-centric with a given subspace ; identifying channels with the calculated one or more parameters matching channel-dropping criteria defined to the given subspace thereby giving rise to omitted channels ; and generating a set of channels selected for the given subspace, the generating comprising excluding the omitted channels from further processing for image reconstruction . calculating one or more parameters of specular points of channels reflected by a virtual equi-area tessellated sphere co-centric with a given subspace ; identifying channels with the calculated one or more parameters matching channel-dropping criteria defined to the given subspace thereby giving rise to omitted channels ; and generating a set of channels selected for the given subspace, the generating comprising excluding the omitted channels from further processing for image reconstruction . <EOS>