Cause 1: Are the X-ray focus setting values appropriate?
Corrective Measures 1: Adjust the focus values.
Click here for "(SMX-225CT) Replacing the Filament - focus".
Cause 2: Is the target rotated regularly?
Corrective Measures 2: Rotate the target.
Click here for "(SMX-225CT) Rotating the X-ray Tube Head Tungsten Target".