Advantages of Response Function Change in a transXend Detector with Various Scintillators as Substrates of Segment Detectors

Abstract

To enable practical computed tomography (CT) that uses the energy information of X-rays, the ''transXend detector'' was developed to provide energy information about incident X-rays by measuring them as an electric current. The transXend detector requires a spectrum survey method in the unfolding process for measuring the energy distribution of incident X-rays, when the response functions of segment detectors have nearly the same behavior. When employing various scintillators with different effective atomic numbers and densities as the substrates of the segment detectors, better convergence is obtained in the unfolding process by using only one initial guess spectrum. Additionally, less dose exposure is possible when using the transXend detector with various segment detectors, compared with the transXend detector that consists of the segment detectors with the same substrate.

Using energy-resolved X-ray computed tomography with a current mode detector to distinguish materials

“…Employing different kinds of scintillators gave the desired range of the response functions. 10) The same effect was obtained by inserting an absorber, such as tin filter, between the segment detectors made of the same material. 11) With inserting a tin filter, the responses of segment detectors in front of and behind the filter would change much to the effect of X-ray absorption by iodine: the behind segment detector would not be sensitive to iodine, because the X-rays above 29.2 keV (K-edge of tin) in energy would be absorbed by the tin filter, whether the X-rays passed through iodine or not.…”

“…The initial guess thickness of iodine was kept zero: it was demonstrated that the initial guess X-ray spectrum without iodine gave proper output, when response functions had variety with using different substrate for segment detectors or inserting an absorber between the segment detectors with the same substrate. 10) The X-ray path length was estimated by a current measurement CT image, which was always available in the measurement with the transXend detector as shown in Fig. 6.…”