and then the carriages are displaced vertically as the subject is scanned from at least two sides in a single pass as a new subject enters the portal for scanning the carriages can begin scanning the subject from their current position as they are displaced vertically in the opposite direction of displacement performed in the previous scan for example one subject is scanned as the carriages are displaced in a vertical direction decreasing in elevation and after the scan is completed and the next subject enters the next subject may be scanned as the carriages are displaced in a vertical direction increasing in elevation in another embodiment of the present invention each carriage may include a source without any detectors coupled to the moveable carriage for example carriages 100 and 110 may each be provided without any of detectors 104 105 106 114 115 and 116 in this example stationary detectors may be provided that detect transmission and or scatter radiation as the carriages are displaced and the sources alternate activation the stationary detectors in this example may still be configurable the stationary detectors may also be provided for example in an array that extends approximately the length of travel of the carriages thereby allowing them to detect radiation similar to the detectors attached to the carriages illustrated in fig1 while fig1 generally illustrates each carriage as.