This document discusses digital radiography (DR) and computed radiography (CR). It describes the key components of DR imaging systems, including the capture element, coupling element, and collection element. Common collection elements are photodiodes, CCDs, and TFTs. CR uses an imaging plate that stores x-ray energy as latent images, which are then read by a CR reader/digitizer and processed into digital images. Direct and indirect DR differ in whether they use a scintillator to convert x-rays to light or use a photoconductor to directly convert x-rays to electron-hole pairs.

1. Digitalradiography
Presented by;
Swastik Sagar Poudel
IOM ,MMC

2. INTRODUCTION

4. ADVANTAGE

5. ADVANTAGE

6. DISADVANTAGE

7. Terms related to DR
DR imaging systems has —
1. Capture element : in which the X- ray is captured. In CR, it is PSP & in DR it
may be CsI., GsOS or a-Se
2. Coupling element :The coupling element is that which transfers the x-ray–
generated signal to the collection element.The coupling element may be a
lens or fiber optic assembly, a contact layer, or a-Se.
3. Collection element: The collection element may be a photodiode, a (CCD),
or (TFT).The photodiode and the CCD are light-sensitive devices that collect
light photons.TheTFT is a charge sensitive device that collects electrons.

9. SCANNED PROJECTION RADIOGRAPHY

10. Contd…

11. A scanned projection radiography of the entire of the
body obtained in computed tomography
(Courtesy,Colin Bray,Baylor College Of Medicine))

12. CHARGED COUPLED DEVICE

14. CHARGED COUPLED DEVICE

15. WORKING OF CCD

17. ADVANTAGE

18. DISADVANTAGE

19. PMT

21. PHOTODIODE

22. NEWER COLLECTION ELEMENTS

23. SUBSTRATE(BODY)
DRAINSOURCE
GATE
(Polysilicon)
INSULATOR(SiO)
G
DS
N-MOS
SUBSTRATE(BODY)
(p-type)
DRAIN
(n-type)
SOURCE
(n-type)
GATE
(Polysilicon)
INSULATOR(SiO)
G
DS
B
SUBSTRATE(BODY)
(n-type)
DRAIN
(p-type)
SOURCE
(p-type)
GATE
(Polysilicon)
INSULATOR(SiO)
G
DS
P-MOS
B
BASIC DESIGN OF MOSFET

24. P-type
N-type
N-type
N-type P-type P-type
GATE
(Polysilicon)
INSULATOR(SiO)
GATE
(Polysilicon)
INSULATOR(SiO)
G
G
G
D
D
S
SDS
N-MOS P-MOS
C-MOS

25. CMOSVS CCD

26. Contd…

27. FLAT PANEL DETECTORS

29. COMPUTED RADIOGRAPHY(CR)
CR cassette with Imaging Plate(IP) Conventional Cassette with Screen-Film
IP
Screen
Film

30. COMPUTED RADIOGRAPHY(CR)

31. IMAGING PLATE

32. IMAGING PLATE

33. CR: Principle

34. What happens in the IP???

36. CR READER(DIGITIZER)

37. MECHANICAL FEATURES

38. OPTICAL FEATURES

39. OPTICAL FEATURES

40. COMPUTER CONTROL

41. What happens inside the CR reader???

43. INSIDE DIGITIZER

44. Advantages of CR

45. Disadvantage

46. DDR

47. DDR
Indirect
Conversion
CsI,GdOS
scintillator
Thin film transistor
CsI
Charge coupled
device
Direct
Conversion
Photoconductor
a-Se

48. Direct DR
Indirect DR
a-Si photodiode/CCD
(CsI/
GdOs)
Basic Difference of Direct DR and
Indirect DR

49. INDIRECT CONVERSION

50. Contd…
CsI

51. Contd…

53. DIRECT CONVERSION

54. Contd…

60. REFERENCES