Digital Radiography Computed radiography, CR Direct radiography or direct digitalradiography, DR Digital subtraction angiography, DSA
Computed Radiography (CR)is the generic term applied to an imaging systemcomprised of:★Photostimulable Storage Phosphorto acquire the x-ray projection image★ CR Readerto extract the electronic latent image★ Digital electronicsto convert the signals to digital form
Computed Radiography (CR) uses verysimilar equipment to conventionalradiography except that in place of a film tocreate the image, an imaging plate (IP) isused. The imaging plate is placed under theobject to be examined and the x-rayexposure is made.
instead of taking an exposed film into adarkroom for developing in chemical tanks oran automatic film processor, the imagingplate is run through a special laser scannerto read and digitize the image.
The CR imaging plate containsphotostimulable storage phosphors, whichstore the radiation level received at eachpoint in local electron energies. When theplate is put through the scanner, thescanning laser beam causes the electrons torelax to lower energy levels, emitting lightthat is detected by a photo-multiplier tube(PMT), which is then converted to anelectronic signal.
The digital image can then be viewedand enhanced using software that hasfunctions very similar to otherconventional digital image-processingsoftware, such as contrast, brightness,filtration and zoom.
GA GT GC GS RN RT RE影像 A 1.2 E 1.6 -0.14 4 R 0.5影像 B 0.9 A 1.6 -0.42 4 R 4.0
GA GT GC GS RN RT RE影像 A 1.0 F 0.7 0.38 4 R 0.5影像 B 1.0 A 0.7 0.10 4 R 5.0
GA GT GC GS RN RT RE影像 A 1.4 0 1.6 0.7 4 Q 1.1影像 B 0.9 A 0.8 0.0 4 Q 5.0
GA GT GC GS RN RT RE影像 A 0.6 0 0.6 0.63 5 T 0.5影像 B 0.9 A 0.6 0.20 5 T 5.0
GA GT GC GS RN RT RE影像 A 0.9 E 1.6 -0.16 4 R 0.5影像 B 0.7 A 1.5 -0.58 4 R 5.0影像 C -1.3 A 1.5 0.66 4 R 5.0
Disadvantages Imaging plates (IPs) are quite expensiveand can be easily damaged, if thesystem being used requires manualhandling of the IPs. Theoretically, IPsmay be reused thousands of times, butconstant use will always result indamage to the IP and image artifacts.