Differentiation of impact intensifiers and flat panel detectors

Image intensifier: The x-ray inspection image intensifier consists of an image intensifier tube, a tube container, a power supply and a bracket. The image intensifier tube is the core component, which is supported by a bracket and fixed in a tube container with anti-magnetic properties. The image intensifier tube is a large-scale high-vacuum tube. The front end of the tube is a large input screen, and the photocathode PC is close to the input screen. The tube wall has focusing electrodes G1, G2, and G3, and the tail has a small area. The output screen has an accelerating electrode A (anode) at the front of the output screen, and each electrode is supplied with the required working voltage by an external circuit. The X-ray passing through the object is projected on the input screen to generate a photon image, and the photocathode generates electrons corresponding to the brightness of the photon image to form an invisible electronic image. The image is focused by an electrostatic lens under the action of the anode electric field. It accelerates towards the anode and projects it on the output screen, producing a visible fluorescent image.
advantage:
High conversion efficiency;
Wide dynamic range;
High spatial resolution;
High X-ray absorption in the low-resolution region (because its atomic number is higher than that of amorphous selenium);
Strong adaptability to the environment;
shortcoming:
Relatively slightly lower than the amorphous selenium type flat panel detector;
The image will be deformed to a certain extent;
Over time, the image will decay to some extent.
After the image is replaced by the CCD for the second time, there will be a certain deviation;
Low resolution accuracy (it is easy to see complete penetration in some places and incomplete penetration in some places);
Small differences cannot be discerned.
Digital flat panel detection: The photoconductive semiconductor directly converts the received X-ray photons into electric charges, and then the electrical signals are read out and digitized by the thin film transistor array.
Specific principle:
1. X-ray incident photons excite electron-hole pairs in the amorphous selenium layer;
2. The electrons and holes move in opposite directions under the action of the applied electric field, generating a current. The magnitude of the current is proportional to the number of incident X-ray photons; 3. These current signals are stored on the interelectrode capacitance of the TFT, and each The TFT and the capacitor form a pixel unit.
advantage:
1. High conversion efficiency of digital transmission;
2. Wide dynamic range;
3. High spatial resolution;
4. The clarity is very good;
5. The image has no deformation;
The image has a strong sense of hierarchy; small differences can be discerned.
long lasting.
shortcoming:
Low absorption rate of X-rays (with the improvement of the process, the image brightness is no different from the image intensifier or even exceeds);
The selenium layer is sensitive to temperature (currently, some workshops and laboratories are relatively stable in temperature; and within the normal temperature range, it will not be affected by images);
The image intensifier was originally born to compensate for the low brightness of the digital flat panel detector. At present, the brightness of the digital flat panel is bright enough (under the same conditions of KV and UA). Image intensifiers are starting to exit the market. At present, many well-known xray devices use digital flat panel detectors. The advantages of flat panel detection cannot be replaced by image intensifiers. And some of the shortcomings of image intensifiers are irreparable.

Author:Image Intensifier