![]() ![]() Ancillary but necessary components include a high-voltage generator, a patient-support device (table or couch) and hardware to allow positioning of the X-ray source assembly and the image receptor assembly relative to the patient.įigure 1. ![]() The key components include an X-ray tube, spectral shaping filters, a field restriction device (aka collimator), an anti-scatter grid, an image receptor, an image processing computer and a display device. IntroductionĪ schematic of an image-intensified fluoroscopy system is shown in Figure 1. This convention is derivative of the appearance of the early non-intensified fluoroscopic screens, and it has been retained in the digital age even though the capability now exists to digitally reverse the grayscale. To achieve high frame rates while keeping cumulative radiation dose to a reasonable level, the radiation dose to the image receptor per image (i.e., per frame) must be kept quite low, about 0.1% of the dose used in radiography.įluoroscopic images appear with an inverted grayscale (black/white is reversed) compared with standard radiographs. At these frame rates, the human visual system cannot distinguish frame-to-frame variation and motion appears to be continuous, without visible flicker. Electronic fluoroscopy systems create this perception by capturing and displaying images at a high frame rate, typically 25 or 30 frames per second. ![]() Patients receive less radiation dose as well, because of the amplification and overall efficiency of the imaging system.įluoroscopy differs from most other X-ray imaging in that the images produced appear in real-time, allowing evaluation of dynamic biological processes and guiding interventions. This results in a substantial reduction in radiation dose to the fluoroscopist. One benefit of the modern system compared to the earlier approach is that the fluoroscopist need not stand in close proximity to the fluorescent screen in order to observe the live image. In modern systems, the fluorescent screen is coupled to an electronic device that amplifies and transforms the glowing light into a video signal suitable for presentation on an electronic display. After passing through the patient, the remnant beam impinged upon the fluorescent screen and produced a visible glow, which was directly observed by the practitioner. Early fluoroscopes consisted simply of an X-ray source and a fluorescent screen, between which the patient was placed. Fluoroscopy, or real-time projection X-ray imaging, has been in clinical use since shortly after Roentgen’s discovery of X-rays. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |