Radiographic density Flashcards
The degree of overall blackening on a radiographic image
DENSITY
CONTROLLING FACTOR AFFECTING RADIOGRAPHIC DENSITY
- MilliAmperage-Second (mAs)
- Determines the number of photons produced by the x-ray tube
- (mA) x (exposure time)
- If mAs is doubled, the radiographic density will double
- If mAs is halved, the radiographic density will be halved
- 1 mAs = 1 Density
mAs and radiographic density have a directly proportional relationship
The intensity of radiation at a given distance from the point source is inversely proportional to the square of the distance (INVERSE SQUARE LAW)
DISTANCE - can affect (no. of e) quantity
- Measurement of the blackness of a film → Densitometer
- Defined as the based 10 logarithm of the opacity
OPTICAL DENSITY (FILM DENSITY)
the ratio of light incident on the film (I0) to the light transmitted by the film (It)
Opacity
5 Basic Radiographic Densities
- AIR
- FAT
- SOFT TISSUE/FLUID
- MINERAL (BONE)
- METAL
The study of how film emulsion respond to radiographic exposure
SENSITOMETRY
a graph which illustrates the manner to which a film or film-screen system responds to different levels of exposure. It is plot with the Log of Exposure on the horizontal axis and the Optical Density on the vertical axis
Characteristic Curve
- Done by exposing different parts of the film to the same intensity of radiation but varying the
- duration of exposure (TIME-SCALE SENSITOMETRY)
- Intensity of radiation (INTENSITY.
SCALE SENSITOMETRY)
EXPOSED & PROCESS THE FILM