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Digital Radiography

Digital Radiography. Anas Athar, DDS. Digital Image. Definition: A digital image is made up of binary language of 0s and 1s arranged in rows and columns called an image matrix. Principle of Film Based Imaging. Film-based image consists of:

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Digital Radiography

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  1. Digital Radiography Anas Athar, DDS

  2. Digital Image Definition: A digital image is made up of binary language of 0s and 1s arranged in rows and columns called an image matrix.

  3. Principle of Film Based Imaging Film-based image consists of: • X-ray interaction with electrons in film emulsion • Production of latent image • Chemical processing • Transformation of latent image into visible image.

  4. Principle of Digital Imaging Digital Image consists of: • X-ray interaction with electrons in electronic sensor pixel • Conversion of analog data to digital data • Computer processing • Display of image on computer screen

  5. Matrix Pixel

  6. Analog Image

  7. Analog to Digital Converter(ADC) ADC transforms analog data into numerical data based on the binary number system

  8. Analog to Digital Converter(ADC) Energy (x-rays) absorbed by each pixel is measured and assigned a number from 0 (black) to 255 (white) according to the intensity of energy absorbed. These numerical assignments translate into 256 shades of gray. *human eye can detect only 32 shades of gray

  9. Image Display

  10. Classification of Digital Image Receptors

  11. Classification of Digital Image Receptors Direct: 1) Charge Couple Device (CCD) 2) Complementary Metal Oxide Semiconductor (CMOS) Indirect: 1) Storage Phosphor Plates

  12. Direct Digital(Solid State Detector) • Solid-state detector composed of an array of x-ray sensitive pixels. • Each pixel consists of electron well into which x-ray energy is deposited upon exposure. • The signals from each pixel is transferred to ADC to display image on monitor.

  13. Direct Digital

  14. Direct Digital

  15. Indirect Digital(SPP) • SPP consist of polyester base coated with crystalline emulsion (europium-activated barium fluorohalide compound). • When these plates are exposed, x-radiation is converted into stored energy. • This energy is released as blue light when plates are exposed to helium-neon laser beam. • This emitted light is intensified in photomultiplier and then converted into digital data.

  16. Indirect Digital(SPP)

  17. Direct Digital Indirect Digital Comparison ExposureLower Higher Image Generation Computer Laser Scanner, Computer Image Viewing Real Time Delayed Resolution8-10 lp/mm 6-8 lp/mm

  18. QUIZ!!!!Name the Radiologist in Picture

  19. Advantages • Instant image viewing • Elimination of photographic process and dark room • Improved gray scale resolution. • Less radiation exposure to the patient. • Teleradiography • Better diagnostic efficacy • Patient education

  20. Disadvantages • High initial investment • Image quality • Sensor size • Infection control • Legal Issues

  21. THANK YOU

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