Ch. 22- Digital Radiography Flat Panel Detector Systems

Question 1

What are the flat-panel detector types?

Answer 1

-Indirect (two step process)
Uses scintillator

-Direct
Direct

Question 2

2. What are the critical elements used in the flat-panel detectors, direct detectors?

Answer 2

Direct dectectors
uses a photoconductor, which is capable of converting light into an electronic signal,

Question 3

What are the critical elements used in the flat-panel detectors, indirect dectotors?

Answer 3

indirect
-Use a scintillator, which converts incoming x-rays photons to light,
-then onversion of light photons to an electronic signal using a photodetector,
amorphous silicon (a-Si:H) layer
-Electrical signal collected by two possible method: (Charge Coupe device (CCD)
and Thin Film Transistor (TFT))

Question 4

2.2 What are two scintillation material types ?

Answer 4

Cesium iodide (CsI)
Gadolinium oxysulfide (Gd2O2S)

Question 5

2.3 What is a CCD?

Answer 5

• These are the light to electronic converters for indirect flat panel detectors,
  in other words, analog-to-digital converter (ADC)
  -light produced from x-ray interactions must be optically coupled to the CCD sensor chip by lenses or fiber optics.

Question 6

2.4 What is a TFT?

Answer 6

• These are the light to electronic converters for indirect flat panel detectors,
  in other words, analog-to-digital converter (ADC)
  -inside of both direct and indirect flat panel detectors
  -Signal collected by detector elements (DEL) or (DEXEL), Size expressed in micrometers

Question 7

2.5 What is DEL comprised of?

Answer 7

-sensing area
-sginal amplifier and switching mechanism
capacitive storage

Question 8

3. What are the difference in image acquisition between Indirect and Direct
   digital radiography (DR) systems? (Indirect)

Answer 8

-A scintillator must first convert incoming x-rays to light photons, which then strike the amophous silicon photocathode and are converted into an electronic signal. This electronic signal is stored as a latent image in the TFT array

Question 9

3.1 3. What are the difference in image acquisition between Indirect and Direct
digital radiography (DR) systems? (direct)

Answer 9

CONSTRUCTED W/ THE AMOPHOUS SELENIUM LAYER POSITIONED OVER THE AMORPHOUS silicon (ignore the all caps) TFT array, w/ an electric field between th etwo layers. This electric field is responsible for interacting w/ the electronic signal fthat x-ray photons were converted into , and moving it to the TFT array, where they are stored as a latent image, and electronic circuitry completes the readout porcess of the latent image

Question 10

4. What are the flat-panel tech features ?

Answer 10

-Portable
Wireles
-sophisticated piece of electronics

-Manufactuers continue to impove features
weight , durability, patient load capacity, etc.

Question 11

5. What is auto-detection panel technology?

Answer 11

-Panels are wireless
- No true generator interface
Presence of x-radiation hitting panel “triggers” TFT to collect
signal
- Exposure terminated by manual timing or automatic
exposure control (AEC)
- Data read-out completed and panel recharges for next
exposure

Question 12

6. What are DR Panel Precautions?

Answer 12

More sophisticated than a cellphone
Damaged panels sent to manufacturer for analysis (“autopsy”)
fluid invasion
weight load restrictions and bending
avoid panel dropping
clean panels according to manufactuer
newer panels have less weight and more durability
Its your responsibility to know and understand manufactuer protocols