Using DR photography

Imaging principle: DR and CR both convert analog information into digital information, and the difference between them mainly lies in the different ways of X-ray acquisition and image conversion. CR is an indirect X-ray conversion technology, which uses IP as X-ray medium. After IP is irradiated by X-rays, the intensity change of X-rays is recorded as a latent image. The intensity of the latent image signal decreases with time. The laser scanner generates red laser or near infrared laser. When the laser beam gradually scans the IP surface, the latent image signal is converted into visible light by the laser (photoluminescence effect). The fluorescence emitted by each point on IP is coupled to the photomultiplier tube through a special optical system. The photomultiplier tube converts optical signals with different intensities at each point into electrical signals, which are amplified and sampled, then sent to an analog-to-digital converter for quantization, and then sent to a computer for imaging. DR directly converts X-ray photons into digital signals by using flat panel detector or fluorescent CCD camera, which has fewer conversion links and reduces noise. The loss of X-ray photon signal is minimized and the image quality is high. DR has no IP transport link, which reduces mechanical failures, improves efficiency and reduces labor intensity. CR system mainly uses IP detector, commonly known as IP board, which is the carrier to collect and record image information. The imaging principle of CR is that IP board has a kind of light-excited phosphor, which can absorb and store X-ray energy when X-rays shine on it. Then, the captured energy can be released under the excitation of additional laser energy with appropriate wavelength. The release process requires a special CR reader. The released energy is converted into voltage by photomultiplier tube, and the voltage is amplified and then input into analog-to-digital converter, converted into digital, sampled and quantized, and stored in computer. Finally, after reading the image, the data on the IP board is eliminated by applying strong light irradiation so that it can be reused. DR generally refers to digital photography based on charge coupled device (CCD) technology, and cesium iodide crystal is commonly used as detector material. After the cesium iodide crystal is irradiated by X-rays, X-ray photons can be directly converted into visible light, and the visible light excites the photodiode under the cesium iodide layer, so that the photodiode generates current, which is then stored in the diode's own capacitance. Then, the electric signal is read out by the reading circuit and quantized into a digital signal. Finally, it is transmitted to the image processor through the communication interface and stored in the computer.