FILM FACTORS Flashcards
• The study of the relationship between the intensity of exposure of the
film and the blackness after processing is called
sensitometry
6 types of FILM FACTORS
SPEED, PROCESSING TIME, PROCESSING TEMPERATURE, LATITUDE, DENSITY, CONTRAST
The two principal measurements involved in sensitometry are the
____ and ______
the processed film.
exposure to the film and the percentage of light transmitted through
The two principal measurements involved in sensitometry are the
____ and ______
the processed film.
exposure to the film and the percentage of light transmitted through
It describe the relationship between OD and radiation exposure.
H & D curve
Hurter and Driffield
– low radiation exposure level
Toe
– intermediate radiation exposure level
– the region in which a properly exposed
radiograph appears
Straight line portion
– high radiation exposure level
Shoulder
Apparatus that are needed to construct a characteristic curve:
- Optical step wedge / sensitometer
- Densitometer - a device that measures OD
Apparatus that are needed to construct a characteristic curve:
- Optical step wedge / sensitometer
- Densitometer - a device that measures OD
The degree of blackening on the radiograph.
• It is a logarithmic function.
• Has a precise numeric value that can be calculated if the level of
light incident on a processed film (Io) and the level of light
transmitted through that film (It
) are measured.
OPTICAL DENSITY
is attributable to the composition of the base and the tint
added to the base to make the radiograph more pleasing to the eye.
Base density
Base density has a value of approximately .
0.1
results from inadvertent exposure of film during storage,
undesirable chemical contamination, improper processing, and a
number of other influences.
Fog density
Fog density on a processed radiograph should not exceed .
0.1