3. Theory of Focal Spot Reproduction
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Why measure the focal spot?
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RTI Slit Camera User’s Manual
Figure 3–3 The tube filament.
To make it possible to view small details of an image, it shall be as clear as possible
with high resolution. There are a number of things that cause blurring of the X-ray
radiograms.
1. Geometrical blurring
a. Focal spot size
b. Object to picture distance
2. Movement blurring
3. Material blurring
Of these things the focal spot size is the only one directly connected to the X-ray
equipment. The other depends on how you perform the imaging.
The Figure 3–4 and Figure 3–5 gives a description of what the size and shape of the
focal spot mean for the reproduction of objects.
Tube filament