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computed radiography
Computed radiography (CR) uses very similar equipment to conventional radiography except that in place of a film to create the image, an imaging plate (IP) made of photostimulable phosphor is used. The imaging plate is housed in a special cassette and placed under the body part or object to be examined and the x-ray exposure is made. Hence, instead of taking an exposed film into a darkroom for developing in chemical tanks or an automatic film processor, the imaging plate is run through a special laser scanner, or CR reader, that reads and digitizes the image. The digital image can then be viewed and enhanced using software that has functions very similar to other conventional digital image-processing software, such as contrast, brightness, filtration and zoom.
==Differences from Direct Radiography==
Computed radiography (CR) is often distinguished from Direct Radiography (DR). CR and DR have many similarities. Both CR and DR use a medium to capture x-ray energy and both produce a digital image that can be enhanced for soft copy diagnosis or further review. Both CR and DR can also present an image within seconds of exposure. CR generally involves the use of a cassette that houses the imaging plate similar to traditional film-screen systems, whereas DR typically captures the image directly onto a flat panel detector without the use of a cassette. Image processing or enhancement can be applied on DR images as well as CR images due to the digital format of each. There are many different types of DR detectors in use in medicine and industry. Each type has its own merits and distinctions and may be applied to certain imaging requirements based on these attributes.
CR and DR should not be confused with fluoroscopy, where there is a continuous beam of radiation, and the images appear on the screen like on a TV. This is the system many people are familiar with, where the image of the article being x-rayed is viewed in real time on a monitor or display. Many people think airports use fluoroscopes for baggage inspection, when in fact LDAs (Linear Diode Arrays) are universally used to generate static images of luggage content. LDAs are also used in a wide variety of other screening and imaging applications, and are also presented in a digital format. Fluorosopes until recently have used a device called an image intensifier to enhance the analog output of the real time x-ray image from a fluorescent screen, viewing the I.I output with a video or CCD camera and digitally enhancing the video to reduce the noise inherent in the system; the latest fluroscopes now use flat detectors read at up to 60 frames per second to yield a real-time image via a dedicated imaging computer.A
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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