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5. Word List
Slit Measurement Using Digital Image
RTI Slit Camera User’s Manual
1.0B
5.
Word List
Word
Explanation
Actual
focal spot
”Area on the surface of the TARGET that that intercepts
the beam of accelerated particles.”
(From the IEC 60788
standard) The TARGET for an X-ray tube is the same as
the anode.
Depiction
An image or reproduction of an object, e.g., as seen trough
a slit as in this case.
Effective
focal spot
”Perpendicular projection of the ACTUAL FOCAL SPOT on
the REFERENCE PLANE.”
(From the IEC 60788 standard)
Enlargement
factor
The factor that enlarges the true focal spot to the
reproduction in the REFERENCE PLANE through the
SLIT.
Denoted by ”E”.
E=
n
m
Focal spot
The same as ”effective focal spot”.
FWFM
Full Width Fifth Maximum.
For a bell shaped curve, distance parallel to the abscissa
axis between the points where the ordinate has one fifth of
its maximum value.
(Analogous to FWHM and FWTM from
the IEC 788 standard)
Length
For measurements over the length of the FOCAL SPOT,
the direction of evaluation shall be parallel to the
longitudinal axis of the X-RAY TUBE ASSEMBLY. If the X-
RAY TUBE ASSEMBLY does not have an identifiable
longitudinal axis, a longitudinal axis shall be specified
together with the FOCAL SPOT characteristics.
(Adapted
from the IEC 60336 standard)
The length is normally parallel to the perpendicular
projection of the anode cathode axis on the REFERENCE
PLANE.
LSF
“
Line Spread Function. In an imaging system, distribution
of the intensity from a line source along a straight line in a
specified image plane where the straight line is normal to