1. Elements of DR Imaging Systems
Capture element
The element/material used to capture the x-ray photon
Coupling element
Transfers the x-ray generated signal to the collection element
Fiber optics, lens, contact layer, or a-Se
Collection element
Photodiode, CCD, TFT, CMOS
Photodiodes, CCDs, and CMOS are light sensitive devices that collect light photons
TFT collect electrons

2. Digital Radiography Type CR Indirect DR Direct DR Capture Element
Barium fluorohalide
CsI
CsI – cesium iodide/GdOD gadolinium oxysulfide
CsI – cesium iodide
a-Se amorphous selenium
Coupling element
Lens or fiber optics
a-Si
Amorphous silicon
Fiber optics or lens
a-Se
Collection element
CMOS
TFT
CCD

3. Indirect w/ CCD and fiber optics
Multiple detectors
Single detector
CCD
Fiber
optic
coupling
CsI capture element

4. Indirect w/CMOS and lens

5. Indirect TFT
a-Si
Coupling
element

6. Direct TFT

7. Review of Indirect DR
Basically there are three types of indirect systems
CCD
A multitude of small CCD (charged coupled devices) receive light from the cesium iodide scintillator.
TFT
The light from scintillator is recorded by a TFT (thin film transistor) that is also called a flat panel detector.
CMOS (complementary metal oxide semiconductor)
A lens focuses light on the CMOS chip

8. Flat panel technology (TFT) indirect and direct DR applications