A method for collecting data for use in image reconstruction of an object being scanned, comprises providing a plurality of detectors disposed in an arc around the object being scanned to detect light passing through the object; impinging a laser beam at a point on the object; integrating the output of each detector at a number of successive time intervals, each time interval being longer than the previous time interval; digitizing the integrated output from each time interval; successively digitizing multiple times the integrated output from the longest time interval and averaging the results; orbiting the detectors and laser beam to another point on a circle; and repeating the above steps until a complete circle has been traversed.