The improvements of the accuracy of mixture synthesis in X-ray imaging using noise correction per pixel was aimed in this study. Direct conversion type detectors with semiconductors were used, and image correction was performed for each pixel. The entire image was synthesized in each energy band, and the results were compared to the image as energy integrated type. The imaging corrected using shot noise showed better contrast for both low and high atomic number areas, synthesizing multiple mixtures in a single image data without compromising contrast. This result could lead to higher accuracy in X-ray imaging for detecting mixed materials.
We have reported on the growth of single-crystal diamond and its application to radiation detectors. This time, we report on the measurement of an imager with a photon-charge counting read out integrated circuit (ROIC) connected to a single-crystal diamond. The single crystal diamond was 3.0 x 3.0mm x 0.5mm thick. The bump connection area of our test ROIC is a 3.2mm x 3.2mm area with 40 x 40 pixels pads with 80µm pitch. Silver-based bumps were formed on short-crystal diamond using a super inkjet printer and bumped to the ROIC using flip chip bonders.
The imaging experiment was conducted by irradiating X-rays at 90 kV and 0.2 mA at 30cm distance. The results showed that the X-ray transmission image with a clear contrast between the area shielded by 2 mm thick lead and the unshielded area was captured, demonstrating a prototype single-crystal diamond-type X-ray imager.
We have developed X-ray imaging sensors of the photon-charge counting type that can discriminate X-ray energy, and also developed conventional energy-integrating X-ray imaging sensors. X-ray imaging started in the medical field, but in recent years, it has become necessary to support high-energy X-rays for applications such as nondestructive testing and security inspection. X-ray has a white spectrum, and its maximum energy is determined by the acceleration voltage and the number of photons is determined by the current. When high output is desired for high-throughput imaging, it is common to increase the voltage as well as the current, and good images have been obtained by the skill of the imaging technician. In this study, we discuss the influence of X-ray energy on imaging in terms of the imaging target and the type of X-ray detector, and argue that energy-differentiated imaging with X-rays is important not only for high-performance imaging but also for simple transmission imaging.
Demand for 3D X-ray CT inspection (in the medical, nondestructive testing, and security fields) is increasing year by year, and AR (Augmented Reality), VR (Virtual Reality), and MR (Mixed Reality) are being used for displaying internal structure of object. Although, these applications can display surface-rendered or volume-rendered objects, but have not been developed to accurately represent and spatially help the observer understand the point he or she wants to see. In this research, the representation method and system were proposed that 2D image output from DICOM is superimposed on the cross-section of a surface-rendered model, and by using a motion sensor, an object imaged with a 3D X-ray CT can be freely manipulated in the virtual space using the human hand, just as if the object were actually moved in real space, so the cross-section of the point to be checked can be viewed in any direction. By using the stencil buffer function, a shader function on Unity, unnecessary areas other than the cross-section can be hidden, so the object itself is not hidden in the 2D image. This system can be performed with either spatial reality display, VR device, or AR glasses. The results show that the proposed method is effective as a useful 3D representation in 3D X-ray CT, which is voxel data containing internal information, and as a method that allows viewing tomographic images in CT images and easily representing specific locations.
This study demonstrates a result of polarization effect of an X-ray imager that uses TlBr detectors with silver small electrodes. Although TlBr detectors are suitable for X-ray imaging applications because of the associated large attenuation coefficients and direct conversion behavior, realizing a flat-panel detector with TlBr involves developing processes. The demonstrated imager is constructed utilizing a combination of existing technologies; it comprises a plate electrode containing thallium metal to suppress the polarization phenomenon, pixelated silver electrodes with 80 µm pitch, and a photon-counting-type readout integrated circuit that can work in the hole as well as electron collection modes. As a result, it was reconfirmed that the polarization phenomenon is a serious problem for small electrodes as well as for large electrodes. In addition, the polarization could have accelerated by high X-rays flux. This result can motivate the development of polarization-tolerant small electrodes for TlBr detectors.
We have reported CdTe FPDs with high resolution imaging and energy distinguish for multi energy spectral CT X-ray imaging, and it can acquire high amount of information. This study developed a system that aggregates and 3DCT-Xray data with boundary extraction function for high speed data communication. In the medical and industrial field, it is necessary to narrow down the desired information and confirm it quickly for mobile devices. The developed system enables to divide high volume information imaging data into multiple low data 3D object data by surface rendering technique. The imaged data were rendered only by host PC and selectively transferred to client device such as smartphone so that user want to check.
Augmented Reality (AR) is a new form of human-machine interaction that superimposes digital information on the real-world environment. AR technology has the ability to organize much of the digital information from X-ray CT imaging. This paper proposes a new system that user can project 3D-Xray AR CT image on the screen of the device such as smartphone and tablets. In the future, the system will be combined with pseudo 3D color display technology by photon counting X-ray CT imaging.
A new photon counting X-ray imager with a 4-sided buttable structure is proposed. The imager consists of a stacked structure of a semiconductor detector such as Cadmium Telluride detector and a Si-based Read-Out Integrated Circuit (ROIC). The imager can be arranged in two dimensions with small gaps of less than 100 μm, because input/output pads of the ROIC are located on the back using through silicon via technology. In addition, daisy-chaining between imagers extends the number of tilings without increasing the number of external connections. This allows to connect small imagers to achieve a larger imaging area.
We already reported TlBr X-ray imager by using our original designed ROIC “photon and charge counting type ROIC”. The silver bumps were used in this imager device for connecting TlBr and ROIC, and this silver bumps were also behaved as silver electrode on TlBr. It is difficult to operate TlBr radiation detector for long time, and Hitomi et.al. reported that the long-time operation could achieved by switching the bias voltage polar for the detector and/or using thallium (Tl) electrode. In our TlBr imager, we designed the ROIC input circuit using bipolar amplifier. In this paper, we use bias polar switching method for long time operation of TlBr X-ray imager, because it is not easy to adapted photo-lithography process of Tl metal for making pixelized TlBr sensor. We use the silver electrode (as also bumping material), and the device structure was TlPb(common electrode)/TlBr/Ag(pixel electrodes and bump material)/ROIC. We will discuss about long time operations in this imager.
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