X-Ray Image Processing
Physics: AQA A Level, topic 10.5.2
Flat Panel (FTP) Detector
Flat panel detectors are used to detect X-rays and produce images.
How it works
- Flat panel (FTP) detectors contain a layer of scintillator material which converts the X-rays into light.
- Behind the scintillator layer is a detector array similar to a TV LCD display.
- Millions of pixels in the display each contain a photodiode which generates an electrical signal.
- The signals from the photodiodes are amplified and read by electronic scanning to produce an accurate representation of the x-ray image.
Benefits of FTP detectors
- The FTP detector is more sensitive and faster than film.
- This allows for a lower dose of radiation.
- The image can also easily be viewed on a tablet computer.
X-Ray Image Enhancement and Detection
X-ray images can be enhanced by a contrast material. Photographic detectors are also used.
Contrast enhancement
- Where there is little difference in contrast between structures being imaged, a contrast material can be supplied.
- For example, a 'barium meal' to give contrast to parts of the intestines.
Photographic detection
- An x-ray image intensifier converts X-rays into visible light.
- Such intensifiers are used to allow low-intensity X-rays to be converted to a bright visible light.
- The device contains an input fluorescent screen, photocathode, electron optics, output fluorescent screen and output window.
Photographic detection cont.
- These parts are all mounted in a high vacuum.
- This allows the viewer to more easily see the structure of the object being imaged than fluorescent screens alone.
- It requires lower doses due to the more efficient conversion of x-ray quanta to visible light.
Test yourself on X-Ray Image Processing
Flat Panel (FTP) Detectors
Why are FTP detectors used instead of photographic film?
What is the role of the scintillator material in an FTP detector?
Why are some patients given a 'barium meal' before they have an X-ray scan?
What is the role of an x-ray image intensifier?