-
Milliamperage (ma) is a major factor in
determining the
quantity of x-rays produced and is, therefore, a good indication of the type of
examination that can be performed with a machine.
-
The m A-s Factor ( time
× milliamperes ) affects film density by
governing the amount of X-ray photons which reach the film emulsion. This,
however only affects film contrast in a negative way, by reducing the contrast
when the mA-s factor is incorrect. If the quantity of X-rays reaching the film
is too low, the film will be pale.
-
The
relationship between ma and time is a direct one. Therefore, a higher ma setting
allows for a corresponding decrease in required exposure time. A second
advantage of a high-ma setting is that
the greater amount of radiation
produced permits examination of thicker portions of the horse.
-
Radiographs
obtained with a setting of 0.1 sec and 100 ma are identical to those obtained
with a setting of 1.0 sec and 10 ma,
assuming that all other factors remain constant. The product of
milliamperage and time is called
milliamperseconds (mas); equal mas settings will produce radiographs of
equal density or contrast. This relationship can be seen in two examples:
-
1.01 sec x ma = 10 mas
-
1.0 sec 10 x ma = 10 mas
-
2.0.05 sec 30 x ma = 1.5 mas
-
0.1 sec 15 x ma = 1.5 mas
-
0.15 sec 10 x ma = 1.5 mas
-
0.3 sec 5 x ma = 1.5 mas
