Digital%20Radiography

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Digital Radiography

• Chapter 22

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History of Digital Radiography

• Slower process of conversion because no pressing
  need to convert to digital radiography.
• Requires a large amount of digital data.

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Overview

• Primary difference is that digital radiographs
  are electronically captured, recorded and viewed
  at a computer terminal which replaces the
  radiographic film and the view box.
• Screen and cassette is replaced by a reusable
  image receptor or detector.
• Receptor receives x-rays and exposes a digital
  plate that transforms light to an electrical
  image.
• Hardware is essentially same (X-ray tube, stand,
  etc).

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• Once digital radiographic image is made, it is
  transferred to a dedicated digital radiography
  computer for image processing.
• Image can then be adjusted, rotated, etc.

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Limitations of Conventional Screen-film
Radiography

• Limitations
• Require fairly narrow exposure factors to produce
  a diagnostic quality radiograph.
• Radiographic image can not be adjusted once it is
  made.
• Requires physical handling and storage.

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Advantages of Digital Radiography

• The image
• Image can be adjusted after exposure.
• Need for re-takes are minimized.
• Computer manipulation of the digital image is
  possible.
• Able to see soft tissue and bony detail in single
  image.
• Studies show that digital films are equal or
  better than traditional film for evaluating most
  body parts.

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• Time
• Reduces time takes to produce image.
• Reduces time taken in re-takes.
• Reduces processing time.
• Time to correctly label and store.

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• Image storage and Transport
• Stored in computer and not physically stored in
  clinic.
• Quick access to digital image.
• Ease of transfer of image.

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• Cost Savings and Increasing Profits
• Overall initial cost is higher, but due to saving
  time and materials, actually will be cheaper in
  the long term.
• Digital improves quality of imaging studies,
  which leads to better diagnosis.
• Follow-up Radiography
• Comparison to previous radiographs is easier.
• Not worried about lost or misplaced radiographs.

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Disadvantages of Digital Radiography

• Training and Learning Curve
• Must learn machinery, technology and positioning.
• Must still adhere to good technique for acquiring
  images.
• Equipment cost
• Initial cost is high compared with traditional
  radiography.
• Other technology costs associated with digital
  radiology (computers, servers, etc).

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Image Management Software and Image Processing

• Some digital radiology machines have pre-set
  selections based on species, body part of
  interest, and radiographic view to further
  identify the study type.
• Images will be sent to workstation or printed on
  transparent film for viewing.

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Analog-to-Digital Radiographic Signal Conversion

• Conventional radiograph is produced by a series
  of analog signals, from x-ray formation and
  interaction with the patient, to capture of
  x-rays by the intensifying screen, which converts
  to light which produces image on the film.
• Digital x-ray converts the analog signal of the
  light to a digital signal. Converts the waves to
  a digital signal.

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Digital Computers

• Digital waveform is represented numerically by
  binary numbers.
• Computer memory and storage consist of bits
  (binary digits).
• Eight bits become one byte.

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Pixels and Image Matrix

• X-ray beam is converted into a electronic form
  that is digitized and converted to squares of
  information known as pixels.
• The smaller the pixel, the better the image
  quality.

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Viewing Digital Images

• Display Monitors
• Consideration given to size and type
• Film and Paper
• Should be printed on high-quality, transparent
  laser film and can be viewed on viewbox.

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Digital Receptors Available in Veterinary Medicine

• Computed Radiography (CR)
• Similar to traditional radiography where CR
  cassette is exposed, opened and image is removed
  from CR plate, then plate is erased and returned
  to cassette for reuse.
• Flat Panel Detectors
• Detectors in a panel that is hard wired to a
  computer.
• Charged Coupled Device (CCD)
• Small flat panel that is capable of producing
  images from visible light.

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Digital Artifacts

• Image plate artifacts
• Cracks and bends in plates
• Image processing artifacts
• Halo effects, computer artifacts

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