What is a DR film?

DR film is a direct digital X-ray photography system.

It consists of electronic cassette, scanning controller, system controller and image monitor. It directly converts X-ray photons into digital images through electronic cassette, which is a generalized direct digital X-ray photography.

In a narrow sense, direct digital photography (DDR) usually refers to digital radiography using the image direct conversion technology of flat panel detector, which is a real direct digital X-ray photography system.

The similarity between DR and CR is that X-ray image information is converted into digital image information, and its exposure latitude has some advantages compared with ordinary screen-increasing film system: the dynamic range of CR and DR is wide, and the exposure latitude is large, which allows technical errors in photography, even in some parts where exposure conditions are difficult to grasp; CR and DR can perform various image post-processing according to clinical needs, such as various image filtering, window width and window level adjustment, zoom roaming, image mosaic and distance, area and density measurement, etc., which provide technical support for detailed observation, before and after comparison and quantitative analysis in image diagnosis. The performance comparison between them is as follows:

1, imaging principle: DR is a direct X-ray conversion technology, and selenium is used as an X-ray detector, so there are few imaging links; CR is an indirect X-ray conversion technology. Using an image board as an X-ray detector, there are more imaging links than DR.

2. Image resolution: DR system has no image blur caused by optical scattering, and the clarity is mainly determined by the pixel size; Because of its own structure, when the CR system is irradiated by X-rays, the phosphorus particles in the image plate scatter X-rays and cause the latent image to be blurred. In the process of reading the latent image, the excitation light of the laser scanner scatters when it passes through the deep part of the image plate, forming stimulated fluorescence along the optical path, blurring the image and reducing the resolution of the image. Therefore, the shortcomings of the current CR system are mainly the poor time resolution, which can not meet the display of dynamic organs and structures.

3.DR is the future development direction, but at present, the structure of DR electronic cassette is14 in×17 in (1in = 2.54 cm). Due to technical limitations, the joints of each piece cannot be seamless. Once one piece is damaged, four pieces must be replaced.

4.CR system is more suitable for X-ray plain film photography, and its non-dedicated model can be matched with many conventional X-ray cameras, which is more suitable for X-ray photography of complex parts and postures; DR system is more suitable for fluoroscopy, spot lighting and various contrast checks. Due to the flux limitation of single machine, it is not easy to use multiple machines to work at the same time to replace conventional X-ray equipment in large hospitals, but it is more suitable for small medical units and clinics to use one machine for multiple purposes. In fact, CR and DR systems will be a pair of parallel systems for a long time.