Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Digital Radiography


Published on

Presentation for a Radiographic Exposure class.

Published in: Technology, Business

Digital Radiography

  1. 3. <ul><li>Computed radiography (CR) which is cassette based. </li></ul><ul><li>Direct Digital Radiography (DR) which is cassette-less. </li></ul><ul><ul><li>Charge-coupled Devices </li></ul></ul><ul><ul><li>Indirect Conversion </li></ul></ul><ul><ul><li>Direct Conversion </li></ul></ul>
  2. 4. <ul><li>Uses photostimulable storage phosphor imaging plates </li></ul><ul><li>Uses existing tube equipment setup </li></ul><ul><li>Needs special cassettes </li></ul><ul><li>Uses a special cassette reader </li></ul><ul><li>Has a computer workstation, viewing station, and if hard copies are needed, a printer </li></ul>
  3. 5. <ul><li>Protective layer </li></ul><ul><ul><li>Insulates IP from handling trauma </li></ul></ul><ul><li>Phosphor layer </li></ul><ul><ul><li>Holds the photostimulable phosphor </li></ul></ul><ul><li>Support layer made of polyester </li></ul><ul><ul><li>The base on which the other layers are coated </li></ul></ul><ul><li>Conductor layer </li></ul><ul><ul><li>Grounds the IP eliminating electrostatic problems </li></ul></ul><ul><li>Light shield layer </li></ul><ul><ul><li>Prevents light from erasing data on the IP </li></ul></ul>
  4. 8. <ul><li>Is a cassette-less system </li></ul><ul><li>Uses a flat panel detector, or a charge-coupled device connected to a computer </li></ul><ul><li>Needs new equipment installation. </li></ul>
  5. 9. <ul><li>This is one type of indirect DR </li></ul><ul><li>It uses Gadolinium Oxysulfide as its X-ray scintillator </li></ul><ul><li>It uses optical lenses to input the light from the scintillator screen onto the CCD </li></ul>
  6. 10. <ul><li>Uses Cesium Iodide or Gadolinium Oxysulfide as the X-ray scintillator </li></ul><ul><li>Uses an amorphous Silicon photodiode to capture light and convert it into an electrical signal </li></ul>
  7. 11. <ul><li>This is a portion of an X-ray detector’s a-Si thin film transistor. </li></ul>
  8. 12. <ul><li>Uses a micro-plated electrode </li></ul><ul><li>Uses an amorphous Selenium photoconductor </li></ul><ul><li>Uses a hydrogenated amorphous silicon (a-Si:H) thin film transistor </li></ul>
  9. 13. <ul><li>Image Processing </li></ul><ul><li>Toleration of Overexposure </li></ul><ul><li>Sensitivity </li></ul><ul><li>Data Clipping </li></ul><ul><li>Spatial Frequency Processing </li></ul><ul><ul><li>Edge enhancement </li></ul></ul><ul><ul><li>Image blurring </li></ul></ul><ul><li>Collimator Edge Identification </li></ul>
  10. 14. <ul><li>A histogram is generated by dividing a scanned area into pixels and determining the signal intensity for each pixel </li></ul><ul><li>The histogram will be compared to the look-up table </li></ul>
  11. 15. <ul><li>CR and DR Imaging plates do not have the typical D log E curve, rather they have a straight line characteristic curve </li></ul><ul><li>The processing computer compares the image receiver data to the look-up table, and is able to compensate for overexposure </li></ul><ul><li>This opens the door for ALARA violations if a tech is purposely setting higher than necessary techniques </li></ul>
  12. 16. <ul><li>Manufacturers have designated a means to ensure adequate IP exposure levels </li></ul><ul><li>The unit of measurement differs from manufacturer to manufacturer </li></ul><ul><li>Fuji uses an S# and a S# of 200 equals 1mR of exposure </li></ul><ul><li>Kodak’s system is the exposure index and 2000 equals 1mR of exposure </li></ul><ul><li>Agfa uses a log median exposure (LgM) and a speed class </li></ul>
  13. 17. <ul><li>In most cases, the IP has more information stored on it than the display system allows </li></ul><ul><li>Exposure data that falls above and below useful levels can be left out </li></ul><ul><li>Also, data which the system deems as clinically irrelevant can be left out </li></ul>
  14. 18. <ul><li>EDGE ENHANCEMENT </li></ul><ul><li>IMAGE BLURRING </li></ul><ul><li>At times, a post-processing algorithm can be used on high noise images to blur the mottled noise into the background. </li></ul>
  15. 19. <ul><li>Artifacts unique to CR / DR can occur during Acquisition, Post-Acquisition, or Display </li></ul><ul><li>This is an example of an image taken with an Agfa cassette backwards. </li></ul>
  16. 20. <ul><li>Phantom images can result from incomplete IP erasure </li></ul><ul><li>Scratches from damaged plates </li></ul><ul><li>Light spots caused by dust </li></ul><ul><li>Fogging due to CR plates being more sensitive to scatter than film </li></ul><ul><li>Quantum mottle </li></ul><ul><li>Heat blur </li></ul><ul><li>Dropout artifacts </li></ul>
  17. 21. <ul><li>Algorithm artifacts </li></ul><ul><li>Dropout artifacts from laser imaging and other laser artifacts </li></ul><ul><li>Histogram errors </li></ul>
  18. 22. <ul><li>Density / Brightness adjustments </li></ul><ul><li>Contrast window width adjustments </li></ul><ul><li>Electronic magnification adjustments </li></ul><ul><li>Image enhancement artifacts </li></ul>