1. DIGITAL RADIOGRAPHY

2. DIGITAL PROJECTION RADIOGRAPHY DEPENDS ON COMPUTER TECHNOLOGY TO PRODUCE DIGITAL RADIOGRAPHIC IMAGE

3. DIGITAL RADIOGRAPHY
REFERS TO THE USE OF DETECTORS THAT CONVERT X-RAY ENERGY TO ELECTRICAL ENERGY THAT IS DELIVERED TO A COMPUTER WHERE THE ANATOMICAL IMAGE IS DIGITALLY PROCESSED AND DISPLAYED.

4. DIGITAL RADIOGRAPHY vs COMPUTED RADIOGRAPHY

5. X-RAYS DR
DETECTORS
ADC

6. X-RAYS CR
CR PLATE
SCANNER
ADC

7. DIGITAL PROJECTION RADIOGRAPHY
COMPUTED RADIOGRAPHY (CR)
DIGITAL RADIOGRAPHY (DR)

8. ELECTRONIC DETECTORS
INDIRECT TECHNIQUE CLASS
DIRECT TECHNIQUE CLASS

9. INDIRECT TECHNIQUE INDIRECT CONVERSION FLAT PANEL DETECTORS
INDIRECT CONVERSION CHARGED COUPLE DEVICE DETECTORS

10. INDIRECT CONVERSION FLAT PANEL DETECTORS
USE THIN LAYERS OF SILICON COMBINED WITH THE ARRAYS OF PHOTODIODES. P.D. IS COATED WITH CESIUM IODIDE OR RARE EARTH MATERIAL- WHEN STRUCK BY REMNANT X-RAYS THEY EMIT LIGHT.
ADVANTAGE: HIGH QDE
DISADVANTAGE: LIGHT DIVERGENCE

11. PHOTODIODE

13. INDIRECT CONVERSION CHARGE COUPLED DEVICE DETECTORS
USE CCD ARRAYS TO RECORD THE VISIBLE LIGHT EMITTED BY A SCINTILLATION CRYSTAL THAT HAS ABSORBED THE ENERGY. AN OPTICAL COUPLING SYSTEM DEMAGNIFIES THIS LIGHT AND SENDS IT TO THE CCD ARRAY.

14. OPTICAL COUPLING

15. CCD

16. DIRECT TECHNIQUE
DIRECT CONVERSION FLAT PANEL DETECTORS

17. DIRECT CONVERSION FLAT PANEL DETECTORS
USE AN AMORPHOUS SELENIUM COATED THIN FILM TRANSISTOR ARRAY THAT DIRECTLY CONVERTS X-RAY ENERGY INTO ELECTRICAL SIGNAL. REMNANT X-RAYS ARE ABSORBED IN THE SELENIUM WHERE THEY FORM ELECTRON-HOLES. CAPACITORS COLLECT THE CHARGE.
ADVANTAGE: NO LIGHT DIVERGENCE

18. READY - The 17"x17" amorphous selenium-based sensor is electrically sensitized and readied for exposure.
                                                                           
EXPOSE - Incident X-ray photons are converted into electron-hole pairs. A transverse electric field separates the electrons and holes and creates a charge image precisely corresponding to the X-ray image.
READOUT - The microplasma line scanner sweeps across the sensor in less than 2 seconds causing readout of the charge image and sensor reset.

19. DR vs CR COMPARISON DR SYSTEM ADVANTAGE DISADVANTAGE IMMEDIATE REDOUT
CASSETTE FREE OPERATION
GOOD FOR HIGH VOLUME RADIOGRAPHY
CAN BE USED FOR MAMMOGRAPHY
DETECTORS CAN BE RE-EXPOSED IMMEDIATELY
MORE EXPENSIVE
CAN NOT BE USED IN PORTABLE RADIOGRAPHY??????
NOT COMPATIBLE WITH EXISTING TABLES

21. PORTABLE????

22. PORTABLE CT???!!

24. 4K MONITORS USED IN MAMMOGRAPHY
MONITORS IN DR 1K 2K 4K
1,000 X 1,000 PIXELS
2,000 X 2,000 PIXELS
4,000 X 4,000 PIXELS
4K MONITORS USED IN MAMMOGRAPHY
AND CHEST RADIOGRAPHY

25. DR TERMS TO KNOW PIXEL VOXEL SPATIAL RESOLUTION DYNAMIC RANGE
CONTRAST RESOLUTION
IMAGE NOISE

26. PIXEL

27. VOXEL sometimes easier to think of a voxel as a volume pixel element.
                                                                                                                  
VOXEL
The formation

28. Spatial resolution of a digital image is related to pixel size
Spatial resolution of a digital image is related to pixel size. The smaller the pixel size the greater the spatial resolution. Therefore, a 1024 x 1024 matrix will provide better resolution than a 512 x 512 matrix. The picture to the left demonstrates the dynamic range of gray that can be achieved with each pixel to form the digital image.

30. CONTRAST RESOLUTION
ABILITY OF A SYSTEM TO RESOLVE ADJACENT STRUCTURES HAVING SIMILAR MASS DENSITY

31. NOISE
Signal          Useful image formation   =    Noise           Erratic Information

33. High SNR, or low system noise, is therefore key to capturing the greatest proportion of useful image information

34. QDE
DQE especially affects one's ability to view small, low-contrast objects.

35. DYNAMIC RANGE
1 BIT
2 BIT

36. DIGITAL IMAGE POSTPROCESSING
WINDOWING
EDGE ENHANCEMENT
IMAGE STITCHING
DYNAMIC RANGE CONTROL

37. WINDOWING

38. EDGE ENHANCEMENT

39. IMAGE STITCHING

40. IMAGE INVERSION