It is essential that radiographs taken in practice should be of diagnostic quality to enable accurate evaluation for the presence of disease/pathology.
Whether you are working with companion animals, horses, farm or exotic species, it is important to properly restrain the patient and position them for optimal exposure of the region of interest and radiographic projection (view).
The beam should be centred over the primary region of interest and the collimation should always be adjusted to the region of interest.
Time in seconds (s)
Focal spot/film distance (FFD)
Object-film distance (OFD)
Object/area of interest (hand) farther away from ‘film/cassette’ (wall) – shadow cast is magnified with blurred edges.
Object/area of interest (hand) near to the ‘film/casette’ (wall) – shadow cast is of nearly equal size with sharp edges.
|Too low||Too high|
|mAs||Image too ‘light’ (underexposed)||Image too ‘dark’ (overexposed)|
|kV||Image with high contrast (too black and white – soft tissue may be lost)||Image with low contrast (too uniformly grey – difficult to distinguish individual structures)|
|FFD||Image overexposed (if other settings unchanged)||Image underexposed (if other settings unchanged)|
|OFD||Cannot be too low!||Image magnification and blurring of edges|
Remember that increasing either mAs or kV will cause the film to be darker, therefore a correctly exposed radiograph relies on both an appropriate mAs and kV setting to be used.
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