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Digital Radiography

Digital Radiography. Fall 2012. filmless’ radiology departments. Diagnostic radiographers have traded their film and chemistry for a computer mouse and monitor advance for Rad Sci Prof, 8/9/99. Digital imaging is the acquisition of images to a computer rather than

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Digital Radiography

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  1. Digital Radiography Fall 2012

  2. filmless’ radiology departments Diagnostic radiographers have traded their film and chemistry for a computer mouse and monitor advance for Rad Sci Prof, 8/9/99

  3. Digital imaging is the acquisition of images to a computer rather than directly to film. What Is Digital Imaging?

  4. New Technology • Has impacted everyone: • Practicing radiologic technologist • Educators • Administrators • Students in the radiologic sciences.

  5. Computed Radiography Fundamentals of Computerized Radiography

  6. Radiology 1895Radiology 2001

  7. CR SYSTEM COMPONENTS • CASSETTES (phosphor plates) • ID STATION • IMAGE PREVIEW (QC) STATION • DIGITIZER • VIEWING STATION

  8. History of CR INDUSTRY • Theory of “filmless radiography” first introduced in 1970 • 1981 Fugi introduced special cassettes with PSP plates (replaces film) • Technology could not support system • First clinical use in Japan - 1983

  9. Predictions • 1980 – Bell Labs believed that Unix would be the worlds dominant operating system • 1982 – Bill Gates thought 640K of main memory would suffice for workplace operating systems ( This presentation is 80,000 kb) • 1984 – IBM predicted that personal computers would not amount to anything

  10. History of CR • By 1998 – over 5,000 CR systems in use nationwide • 1998 – Local area hospitals begin to incorporate CR systems in their departments • (Riverside Co. Hosp builds new hospital in Moreno Valley) – completely CR system – 1st generation equipment

  11. TERMINOLOGY • F/S - Film/Screen (currently used method) • CR - Computed Radiography • DR - Digital Radiography • DDR - Direct to Digital Radiography

  12. IMAGE CREATION • SAME RADIOGRAPHY EQUIPMENT USED • THE DIFFERENCE IS HOW IT IS • CAPTURED • STORED • VIEWED • And POST -PROCESSED

  13. Conventional vs. Digital Imaging • Conventional X-ray imaging systems • Produce an analog image (radiographs, & fluoroscopy). • Using x-ray tube with films & cassettes

  14. Conventional vs. Digital Imaging • Digital radiography systems require that the electronic signal be converted to a digital signal – • Using x-ray tube – • CR cassettes with phosphor plate (PSP) • DR systems with transistors (TFT)

  15. COMPUTED RADIOGRAPHY & DIRECT RADIOGRAPHY& FILM SCREENIMAGE CAPTURE FS - Film inside of cassette CR – Photostimuable Phosphor Plate (PSP) DR(DDR) - Thin Film Transitor (TFT)

  16. Cassette with film CR with PSP

  17. Directed Digital Radiography(DDR) Directed digital radiography, a term used to describe total electronic imaging capturing. Eliminates the need for an image plate altogether.

  18. Amorphous Selenium detector technology for DR Direct Radiography

  19. IMAGE CAPTURE • CR • PSP – photostimulable phosphor plate • Replaces film in the cassette • DR – No cassette- • Photons captured directly onto TFT • Sent directly to a monitor

  20. CR PSP in cassette Digital image Scanned & read- CR reader COMPUTER Image stored on computer Viewed on a Monitor Hard copy (film) can be made with laser printer FILM Film in cassette loaded in a darkroom Processed in a processor FILM Hard copy image – stores the image Viewboxes – view the images CR vs. FS

  21. CR BASICS • Eliminates the need for film as a recording, storage & viewing medium. • PSP Plate – receiver • Archive Manager – storage • Monitor - Viewing

  22. General Overview CR • PSP cassette exposed by conventional X-ray equipment. • Latent image generated as a matrix of trapped electrons in the plate.

  23. CR – PSP plate • Photostimulable phosphor (PSP) plate • Captures photons • Stored in traps on plate (latent image) • PLATE scanned in CR READER

  24. CR – PSP plate • Stimulated by a RED LIGHT • Energy is RELEASED in a form of BLUE light • LIGHT captured by photomultiplier tube (PMT) • Changed to a digital signal

  25. How CR works • Blue released light is captured by a PMT (photo multiplier tube) • This light is sent as a digital signal to the computer • The intensity (brightness) of the light – correlates to the density on the image

  26. CR “PROCESSORS”

  27. Densities of the IMAGE • The light is proportional to amount of light received • Digital values are then equivalent (not exactly the same) to a value of optical density (OD) from a film, at that location of the image

  28. ERASING PLATE • After image is recorded • Plate is erased with high intensity white light • Cassettes are reused

  29. CR VS. DR (slide 41) • CR -Indirect capture where the image is first captured on plate and stored = then converted to digital signal • DDR -Direct capture where the image is acquired immediately as a matrix of pixels – sent to a monitor

  30. Digital Radiography Direct Capture Indirect Capture Computed Radiography (CR) Direct-to-Digital Radiography (DDR)

  31. DIRECT RADIOGRAPHY • Uses a transistor receiver (like bucky) • Captures and converts x-ray energy directly into digital signal • Images seen immediately on monitor • Sent to PACS/ printer/ other workstations FOR VIEWING

  32. CR Imaging plate Processed in a Digital Reader Signal sent to computer Viewed on a monitor DR Transistor receiver (like bucky) Directly into digital signal Seen immediately on monitor CR vs DR

  33. ADVANTAGE OF CR/DR • Can optimize image quality • Can manipulate digital data • Improves visualization of anatomy and pathology • AFTER EXPOSURE TO PATIENT

  34. ADVANTAGE OF CR/DR • Changes made to image after the exposure • Can eliminate the need to repeat the exposure

  35. ADVANTAGE OF CR/DR vs FS • Rapid storage • Retrieval of images NO LOST FILMS! • PAC (storage management) • Teleradiology - long distance transmission of image information • Economic advantage - at least in the long run?

  36. CR/DR VS FILM/SCREEN • FILM- these can not be modified once processed • If copied – lose quality • DR/CR – print from file – no loss of quality

  37. “No fault” TECHNIQUES F/S: RT must choose technical factors (mAs & kvp) to optimally visualize anatomic detail CR: the selection of processing algorithms and anatomical regions controls how the acquired latent image is presented for display • HOW THE IMAGE LOOKS CAN BE ALTERED BY THE COMPUTER – EVEN WHEN “BAD” TECHNIQUES ARE SET

  38. DR • Initial expense high • Very low dose to pt – • Image quality of 100s using a 400s technique • Therefore ¼ the dose needed to make the image

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