Low-dose energy-resolved X-ray computed tomography using a filter-changing two-dimensional transXend detector

A novel detector system 'transXend' detector, which measured X-rays as electric current and output the energy distribution of X-rays after analysis, has been developed by the authors. With computed tomography (CT) by using the transXend detector, CT image was given in the absolute value of linear attenuation coefficient as a function of X-ray energy and the effective atomic number distribution in a subject was obtained. For the X-ray CT of a large object such as a human body, the development of a two-dimensional transXend detector is necessary and the authors proposed a filter-changing transXend detector previously. The exposure dose to the subject, however, increased due to the multiple inspections with various X-ray spectra tailored by each filter. To reduce the exposure dose, a method is proposed to synchronize filter changes with changes of the inspection angle of the subject. With this method, the exposure dose can be reduced nearly 50% compared to a conventional electric current measurement CT.