Application of charge-injection devices for digital X-ray imaging using a planar gas-type X-ray detector

We have developed a planar gas-type detector, based on a charge injection device; this device can be used for digital X-ray imaging. Previously, in order to obtain X-ray images, a planar gas-type detector utilized a line-scanning module based on a one-dimensional readout system; however, that technology suffered from a limitation such as a long readout time, not suitable for a fluoroscopy or a moving imaging acquisition. In this study, a readout module based on charge-injection devices was used in conjunction with the planar gas-type detector to acquire signals and two-dimensional digital images. In the original design, two orthogonally cross-shaped top electrodes, called X address and Y address, played important roles in transferring and collecting the generated charges using electrical potential. During the optimization process, the shape of these top electrodes was modified into a honeycomb shape to increase the efficacy of charge collection. A mixture of gas and dielectric layers were selected to make an efficient gas-type detector for digital X-ray imaging. From the result, the electrical properties of the detector were investigated and the effectiveness of its geometrical design was proved. Measurements demonstrated the linearity of X-ray detection, and the successful movement and collection of charge using electrical potential. Thus, this modified planar gas-type detector and charge readout module using a charge-injection device made it possible to obtain two-dimensional images without using a scanning mode.