Image Characteristics
- Contrast Resolution
- Spatial Resolution
- Detector Latitude
- Detector Sensitivity
- Signal to noise ratio
CONTRAST RESOLUTION
- Contrast resolution is the ability to distinguish different densities in the radiographic image.
- Current digital detectors capture data at 8-, 10-, 12-, or 16-bit depths.
- The bit depth is a power of 2.
- Spatial resolution is the capacity for distinguishing fine detail.
- The theoretical limit of resolution is a function of picture element (pixel) size for digital imaging systems.
Film based IOPA – 20 lp / mm.
Digital receptors 7 lp / mm.
Film > CCD > PSP
Detector Latitude
It is the ability of the image receptor to capture a range of x-ray exposures as different densities.
- The latitude ofCCD and CMOS detectors is similar to film
Photostimulable phosphor receptors have larger latitudes and have a linear response to five orders of magnitude of x-ray exposure.
Detector Sensitivity
- Sensitivity of a detector is its ability to respond to small amounts of radiation. Intraoral film sensitivity is classified according to speed.
- High resolution CCD and CMOS systems achieve less dose reduction than lower resolution PSP systems. CCD and PSP systems or extraoral imaging require exposures similar to those needed for 200-speed screen-film systems.
REFERENCE-WHITE AND PHAROAH 5TH EDITION
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