Chapter 1 Introduction to Digital Radiography in addition to PACS Objectives Define the ter
Milk, Bobby, Host, All Things Considered has reference to this Academic Journal, PHwiki organized this Journal Chapter 1 Introduction to Digital Radiography in addition to PACS Objectives Define the term digital imaging. Explain latent image as long as mation as long as conventional radiography. Describe the latent image as long as mation process as long as computed radiography. Objectives Compare in addition to contrast the latent image as long as mation process as long as indirect capture digital radiography in addition to direct capture digital radiography. Explain what a PACS (picture archiving in addition to communication system) is in addition to how it is used. Define digital imaging in addition to communications in medicine.
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Key Terms Computed radiography DICOM (digital imaging in addition to communications in medicine) Digital imaging Digital radiography Direct capture DR Indirect capture DR PACS Teleradiology Conventional Radiography Method is film-based. Method uses intensifying screens. Film is placed between two screens. Screens emit light when x-rays strike them. Film is processed chemically. Processed film is viewed on lightbox. Digital Imaging Digital imaging is a broad term. Term was first used medically in 1970s in computed tomography (CT). Digital imaging is defined as any image acquisition process that produces an electronic image that can be viewed in addition to manipulated on a computer. In radiology, images can be sent via computer networks to a variety of locations.
Historical Development of Digital Imaging CT coupled imaging devices in addition to the computer. Early CT scanners required hours to produce a single slice. Reconstruction images took several days to produce. First CT scanners imaged the head only. First scanner was developed by Siemens. Historical Development of Digital Imaging Magnetic resonance imaging (MRI) became available in the early 1980s. Lauterbur paper in 1973 sparked companies to research MRI. Many scientists in addition to researchers were involved. Advancements in fluoroscopy occurred in the 1970s as well. Analog-to-digital converters allowed real-time images to be viewed on TV monitors. Historical Development of Digital Imaging Fluoroscopic images could also be stored on a computer. Ultrasound in addition to nuclear medicine used screen capture to grab the image in addition to convert it digitally. Eventually, mammography converted to digital as long as mat.
Digital Radiography Development Concept began with Albert Jutras in Canada in the 1950s. Early PACS systems were developed by the military to send images between Veterans Administration hospitals in the 1980s. Development was encouraged in addition to supported by the U.S. government. Digital Radiography Development Early process involved scanning radiographs into the computer in addition to sending them from computer to computer. Images were then stored in PACS. Computed in addition to digital radiography followed. Computed Radiography Uses storage phosphor plates Uses existing equipment Requires special cassettes Requires a special cassette reader Uses a computer workstation in addition to viewing station in addition to a printer
Computed Radiography Storage phosphor plates are similar to intensifying screens. Imaging plate stores x-ray energy as long as an extended time. Process was first introduced in the United States by Fuji Medical Systems of Japan in 1983. First system used a phosphor storage plate, a reader, in addition to a laser printer. Computed Radiography Method was slow to be accepted by radiologists. Installation increased in the early 1990s. More in addition to more hospitals are replacing film/screen technology with digital systems. Digital Radiography Cassetteless system Uses a flat panel detector or charge-coupled device (CCD) hard-wired to computer Requires new installation of room or retrofit
Digital Radiography Two types of digital radiography Indirect capture DR Machine absorbs x-rays in addition to converts them to light. CCD or thin-film transistor (TFT) converts light to electric signals. Computer processes electric signals. Images are viewed on computer monitor. Digital Radiography Direct capture DR Photoconductor absorbs x-rays. TFT collects signal. Electrical signal is sent to computer as long as processing. Image is viewed on computer screen. Digital Radiography First clinical application was in 1970s in digital subtraction. University of Arizona scientists applied the technique. Several companies began developing large field detectors.
Digital Radiography DR used CCD technology developed by the military in addition to then used TFT arrays shortly after. CCD in addition to TFT technology developed in addition to continues to develop in parallel. No one technology has proved to be better than the other. Comparison of Film to CR in addition to DR For conventional x-ray film in addition to computed radiography (CR), a traditional x-ray room with a table in addition to wall Bucky is required. For DR, a detector replaces the Bucky apparatus in the table in addition to wall st in addition to . Conventional in addition to CR efficiency ratings are about the same. DR is much more efficient, in addition to image is available immediately. Comparison of Film to CR in addition to DR Latent image as long as mation is different in CR in addition to DR. Conventional film/screen Film is placed inside of a cassette that contains an intensifying screen. X-rays strike the intensifying screen, in addition to light is produced. The light in addition to x-ray photons interact with the silver halide grains in the film emulsion.
Comparison of Film to CR in addition to DR An electron is ejected from the halide. Ejected electron is attracted to the sensitivity speck. Speck now has a negative charge, in addition to silver ions will be attracted to equal out the charge. Process happens many times within the emulsion to as long as m the latent image. After chemical processing, the sensitivity specks will be processed into black metallic silver in addition to the manifest image is as long as med. Comparison of Film to CR in addition to DR CR A storage phosphor plate is placed inside of CR cassette. Most storage phosphor plates are made of a barium fluorohalide. When x-rays strike the photosensitive phosphor, some light is given off. Some of the photon energy is deposited within the phosphor particles to create the latent image. The phosphor plate is then fed through the CR reader. Comparison of Film to CR in addition to DR CR, continued Focused laser light is scanned over the plate, causing the electrons to return to their original state, emitting light in the process. This light is picked up by a photomultiplier tube in addition to converted into an electrical signal. The electrical signal is then sent through an analog-to-digital converter to produce a digital image that can then be sent to the technologist review station.
Comparison of Film to CR in addition to DR DR No cassettes are required. The image acquisition device is built into the table in addition to /or wall st in addition to or is enclosed in a portable device. Two distinct image acquisition methods are indirect capture in addition to direct capture. Comparison of Film to CR in addition to DR DR, continued Indirect capture is similar to CR in that the x-ray energy stimulates a scintillator, which gives off light that is detected in addition to turned into an electrical signal. With direct capture, the x-ray energy is detected by a photoconductor that converts it directly to a digital electrical signal. Image Processing Conventional radiography Image is determined by the film itself in addition to the chemicals. CR in addition to DR Image processing takes place in a computer. For CR, the computer is located near the readers. For DR, the computer is located next to x-ray console, or it may be integrated within the console, in addition to the image is processed be as long as e moving on to the next exposure.
Exposure Latitude or Dynamic Range Conventional radiography Based on the characteristic response of the film, which is nonlinear. Radiographic contrast is primarily controlled by kilovoltage peak. Optical density on film is primarily controlled by milliampere-second setting. Exposure Latitude or Dynamic Range CR in addition to DR Contain a detector that can respond in a linear manner. Exposure latitude is wide, allowing the single detector to be sensitive to a wide range of exposures. Kilovoltage peak still influences subject contrast, but radiographic contrast is primarily controlled by an image processing look-up table. Milliampere-second setting has more control over image noise, whereas density is controlled by image-processing algorithms. Scatter Sensitivity It is important to minimize scattered radiation with all three acquisition systems. CR in addition to DR can be more sensitive to scatter than screen/film. Materials used in the many CR in addition to DR image acquisition devices are more sensitive to low-energy photons.
PACS Uses Orthopedic workstations are available as long as the following: Surgeons can plan joint replacement surgery. Specialized software allows matching of best replacement as long as patient with patient anatomy. System saves time in addition to provides better fit.
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