Download presentation
Presentation is loading. Please wait.
Published byLora Oliver Modified over 6 years ago
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
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.