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

• 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