1. Overview of CR and DR Gyeongsang National University Hospital
10/11/2018
Overview of CR and DR
Gyeongsang National University Hospital
Department of Diagnostic Radiology
Radiation Technologist: You Dai In

2. Direct Radiography (DR)
Overview of DR systems
CCD based systems
TFT + Phosphor
TFT + Photoconductor

3. Detector technology:CCD based systems
A. Lens Coupling
B. Fiber optic coupling
C. multiple detectors
A phosphor screen converts X-rays into visual light that is projected onto a CCD or onto a CCD-array

4. CCD based systems Mature technology
10/11/2018
CCD based systems
Mature technology
Mostly dedicated applications: mammography, chest
FDA approved except for mammography

5. Detector technology:TFT + Phosphor
Phosphor screen
converts X-ray photons
into visual photons.
Phosphor
Photodiode converts
visual photons into electrons
Electrons are stored on
capacity of switching element

6. TFT + Phosphor GOS systems: available on the market
10/11/2018
TFT + Phosphor
GOS systems: available on the market
CsI systems: limited availability
FDA approved

7. Detector technology:TFT + Photoconductor
Charge transport in photoconductor
Electrons migrate to surface electrode
Electrons are stored on
capacity of switching element

8. Experimental except Hologics
10/11/2018
TFT + Photoconductor
Experimental except Hologics

9. Weaknesses of TFT systems
Low yield of TFT array fabrication
Ghost images
Charge trapping in amorphous semiconductors
Clustering of Tl+ dopant in CsI needles
Limited dynamic range (a- Se) due to high dark current
Image deformation beyond w>Nyquist due to aliassing (a-Se)
Electronic noise in low dose applications
Detector damage at high dose (capacitor overload)

10. Principle of CR Galvanometer Photomultiplier Electrical Signal Laser
Light
guide
A/D
Storage phosphor plate
Digitisation
Rollers I 00

11. Computed Radiography Mature and robust technology
10/11/2018
Computed Radiography
Mature and robust technology
FDA approved and clinically accepted for all applications except mammography

12. CR and DR: Economics Flat Panel Investment $250-300K for one room
$100K to replace damaged detector DR 20% higher productivity
6 pat./h x 2exp./pat. x 10h/day x 200 days/yr = exp/yr
1 room = exp./yr
Amortisation 5 yrs = exp.
$ / exp. = $2.90/exp. CR
Investment $150K for 3 to 4 rooms
$1K to replace damaged detector CR productivity ~conventional
5 pat./h x 2exp./pat. x 10h/day x 200 days/yr = exp/yr
3 rooms = exp./yr
Amortisation 5 yrs = exp.
$ / exp. = $0.50/exp.

13. CR/DR world market evolution 1996-2005

14. 10/11/2018
Assumptions
Penetration of digital acquisition in the x ray rooms will evolve from 2.5% in 1999 to 11% in 2005
Within this digital segment, DR will substitute CR differently according to the application:
Mobile: 100% retention of CR by 2005
Chest: 0% retention of CR
General Rad high end: 70% retention of CR
General Rad low end: 85% retention of CR

15. New flat panel digital detectors are compact,
10/11/2018
CR and DR
New flat panel digital detectors are compact,
offer fast image acquisition and promise excellent image quality CR
In the last 10 years new technologies to make digital radiographic images have emerged. These technologies have developed into systems that are market ripe today. The common name for these new systems is direct radiography systems, or shortly, DR systems.
Whithin the DR systems, especially flat-panel systems may be a threat to CR. Flat-panel detectors are very compact and offer fast image acquisition. In DR, no cassette handling is needed, which for some applications, is an advantage. DR
Flat panel

16. Evolution of Digital Radiography Detector

17. Innovation in Plate technology
10/11/2018
Innovation in Plate technology
more absorption
higher sharpness
higher image quality
“state of the art CR”
Powder Phosphor BaFBr
Needle Phosphor CsBr

18. New CsBr:Eu PhosphorHigher image quality
Cubic crystal facilitates needle growth
Equivalent specific X-ray absorption: ( =4.44 vs. 5.1 g/cm3)
Efficient stimulation with diode laser (stimulation 685 nm)
Efficient detection with PMT or CCD (emission 450 nm)
Excellent storage phosphor:
Conversion efficiency > BaFBr:Eu
(more light / absorbed X-ray)
Lower stimulation energy
 Read-out requires 3 times less laser power

19. DQE, 2,5 µGy (SC 400) 70 kV, 0.5mm Cu-Filter

20. Scanhead line scanner:Higher throughput
Fast acquisition (5s scan, 20s cycle)
QE CCD > QE PMT  Higher gain
Flying Spot Scanhead
 Scan: pixel per pixel  Scan: line per line
 Detector: Photomultiplier  Detector: CCD
Photo
Detector
Fiber Optic
Phosphor Image Plate
Galvo
Light Beam
Collimator
Laser
Scan-Head
SHT
Phosphor Image Plate

21. Scanhead - Scanning Principles
Laser Diode Array
CCD Sensor
CCD Sensor
Optics
Optics
Image Plate
Image Plate
Laser Diode
Array
Front-Stimulation
ADC Stratus
Back-Stimulation
CR Panel

22. Scanhead - 17” Front stimulation
10/11/2018
Scanhead - 17” Front stimulation

23. Scanhead - 17” Prototype(Back-Stimulation)

24. Scanhead, the unifying technology
10/11/2018
Scanhead, the unifying technology CR
(DR)
simple
mature
robust
economic
multi-application
Scanhead
Phosphor Image Plate
fast
compact
integrated
higher image quality
AGFA - Patent

25. 10/11/2018
Ideal DR System

26. DR Detector Technologies

27. CR and DR DQE

28. DQE

30. Conclusions The different technologies will coexist
Best choice will depend on application
CR potential is promising
The difference between CR and DR technology will become less relevant