FIFTH CANADIAN CONFERENCE ON NONDESTRUCTIVE ... - IAEA

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SENSITOMETRIC VALUES FOR INDUSTRIAL RADIOGRAPHY
W.E.3. UcK.Lnne.ij
E.I. Vu Font Vz Ne.mou.ii, ä Co., Inc.
Wilmington, Vzta.wa.ne.
U.S.A.
SENSITOMETRIC VALUES FOR INDUSTRIAL RADIOGRAPHY
ABSTRACT
In measuring sensitometric values of different film products, or in the use
of sensitometry as a quality control tool, several methods may be used. This
paper discusses indicated versus calculated values. Examples are given of
the various calculated values.
INTRODUCTION
In NOT Quality Control, it is often necessary to produce film that meets
specific sensitometric values. Perhaps more important is to log the values
of test films and to monitor the trends so as to insure consistency. Trend
charts may be constructed frcm indicated or calculated values as outlined
below.
SPEED
o Indicated: Read the density of the step closest to Density 2.00 If
one step reads D 1.85 and the next higher step reads D 2.20,
choose the higher step as standard. Remember this "value"
is influenced by base plus fog. Indicated speed may also be
derived by "eye-balling" (visual comparative analysis).
o Calculated: Locate the coordinate of D 2.00+B+F on the H&D curve. Draw
a line down from this point to intercept the Bit speed calculation
bar*. If your graph paper lacks the calculator set
one up beginning at Step 11 = 16.0 Bits, Step 9 = 17.0 Bits,
etc. A Bit Speed of 16.0 = Arithmetic Speed of 100; 17 = 200;
15 = 50. Alternately, if Step 11 represents a 100 speed, then
Step 12 is a 41% increase in energy or about 20% slower speed.
Step 13 represents half the speed of Step 11 or 50.
*Du Pont H&D Graph Paper.