We designed hybrid x-ray detector and simulated using Monte Carlo method. Hybrid x-ray detectors consist of scintillator coupled photoconductor structure. In the hybrid structure, x-ray photons are converted into the light photon in the scintillator layer and light photons are converted into the electric charge in the semiconductor layer. The electric charges can be generated from directly x-ray absorption in the semiconductor material. We design the columnar CsI:Na as scintillator layer and a-Se as photoconductor material. When x-ray photon incident the scintillator layer, the photons are distributed through the scintillator, and then generated light photon influence the semiconductor material. We study the light photon distribution according to the scintillator layer thickness and the detector pixel size which have influence on image resolution.
In this paper, we investigated electrical characteristics of the X-ray detector of mercuric iodide (HgI2) film fabricated by PIB(Particle-In-Binder) Method with thicknesses ranging from approximately 200μm to 240μm. In the present study, using I-V measurements, their electrical properties such as leakage current, X-ray sensitivity, and signal-to-noise ratio (SNR),were investigated. The results of our study can be useful in the future design and optimization of direct active-matrix flat-panel detectors (AMFPD) for various digital X-ray imaging modalities.
There has been considerable recent progress in II-IV semiconductor materials and in methods for improving performance of the associated digital x-ray detectors. Cd1-xZnxTe is known as promising medical x-ray detector material. The CdTe and Cd1-xZnxTe (x=0.15,0.25,0.3) detectors were fabricated by vacuum thermal evaporator for the large area deposition. First, the stoichimetric ratio and the x-ray diffraction of the deposited (Cd,Zn)Te films were analyzed by EPMA and XRD. Secondly, leakage current, x-ray sensitivity, SNR, and linearity were measured to analyze the x-ray detection effect of Zn in (Cd,Zn)Te film. Experimental results showed that the increase of Zn concentration rates in Cd1-xZnxTe detectors reduced the leakage current and improved the x-ray detection performance.
Nowadays, large area, flat panel solid state detectors are being investigated for digital radiography. In this paper, development and evaluation of a selenium-based flat-panel digital x-ray detector are described. The prototype detector has a pixel pitch of 139μm and a total active imaging area of 7"× 8.5", giving a total of 1.9 million pixel.
This detector include a x-ray imaging layer of amorphous selenium as a photoconductor which is evaporated in vacuum state on a TFT flat panel, to make signals in proportion to incident x-ray. The film thickness was about 500μm. To evaluate the imaging performance of the digital radiography (DR) system developed in our group, sensitivity, linearity of the response of exposure, the modulation transfer function (MTF) and detective quantum efficiency (DQE) of detector was measured. The measured sensitivity was 4.16 x 106 ehp/pixel•mR at the bias field of 10 V/μm: The beam condition was 41.9 KeV. Measured MTF at 2.5 lp/mm was 52%, and the DQE at 1.5 lp/mm was 75%. And the excellent linearity was showed where the coefficient of determination (r2) is 0.9693.