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 2018-11-10

Direct Radiography (DR) Overview of DR systems CCD based systems TFT + Phosphor TFT + Photoconductor 2018-11-10

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 2018-11-10

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

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 2018-11-10

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 2018-11-10

Detector technology:TFT + Photoconductor Charge transport in photoconductor Electrons migrate to surface electrode Electrons are stored on capacity of switching element 2018-11-10

Experimental except Hologics 10/11/2018 TFT + Photoconductor Experimental except Hologics 2018-11-10

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) 2018-11-10

Principle of CR Galvanometer Photomultiplier Electrical Signal Laser Light guide A/D Storage phosphor plate Digitisation Rollers I 00 2018-11-10

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 2018-11-10

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 = 24 000 exp/yr 1 room = 24 000 exp./yr Amortisation 5 yrs = 120 000 exp. $350 000 / 120 000 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 = 20 000 exp/yr 3 rooms = 60 000 exp./yr Amortisation 5 yrs = 300 000 exp. $150 000 / 300 000 exp. = $0.50/exp. 2018-11-10

CR/DR world market evolution 1996-2005 2018-11-10

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 2018-11-10

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 2018-11-10

Evolution of Digital Radiography Detector 2018-11-10

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 2018-11-10

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 2018-11-10

DQE, 2,5 µGy (SC 400) 70 kV, 0.5mm Cu-Filter 2018-11-10

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 2018-11-10

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 2018-11-10

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

Scanhead - 17” Prototype(Back-Stimulation) 2018-11-10

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 2018-11-10

10/11/2018 Ideal DR System 2018-11-10

DR Detector Technologies 2018-11-10

CR and DR DQE 2018-11-10

DQE 2018-11-10

2018-11-10

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 2018-11-10