Carter - Ch. 6

CCD’s

• Oldest indirect conversion

• SEQUENCE:

  • X-ray interact with scintillation material

  • Sent to capacitors which convert light into electrical charge

  • Charge sent to ADC

• Structure - silicon chip

• Cesium Iodide-structured phosphor (similar to a TFT) reducing light spread

• Lenses or fiber optics focus light onto chip

• Used in fluoro, C-arms for trauma or forensic and stereotactic breast biopsy

CMOS

Complementary metal oxide semiconductor

• Highly efficient and inexpensive

• More susceptible to noise so lower quality, lower resolution and lower sensitivity as compared to CCD’s

• Convert light into electrons-stored in capacitors within the pixel then to ADC

Binning

Binning allows charges from adjacent pixels to be combined on the sensor before the charge is readout through the amplifier, the dominant noise source on a CCD.

-Part of CCD

dont need