A high energy X-ray computed tomography using silicon semiconductor detectors

Second- and third-generation high energy industrial X-ray computed tomography systems using silicon semiconductor detectors were developed. Both systems consist of a high energy X-ray source using an electron linear accelerator with the maximum energy of 6 MeV and an array detector unit using silicon semiconductor detectors. This unit also includes a collimator with slits 0.2 mm wide and 1.4 mm high, located in front of the detectors. To increase sensitivity, detector elements were placed parallel to the X-ray beams, The third-generation system had 512 detector elements arrayed with 1.3 mm pitch. To reduce detector pitch, each detector chip was mounted on a tungsten base plate using a thin film circuit board. The plate acts as shield to absorb incoming scattered X-rays and secondary electrons generated at neighbor detectors. Performance tests were carried out in the second- and third-generation systems. The spatial resolution of 0.30 mm was confirmed for an iron test piece of 70 mm diameter using the second-generation system. The scans for a slice were completed within less than 10 seconds in the third-generation system.