exposure charts

1. M.KARTHIKEYAN
ASSISTANT PROFESSOR
DEPARTMENT OF MECHANICAL ENGINEERING
AAA COLLEGE OF ENGINEERING & TECHNOLOGY, SIVAKASI
karthikeyan@aaacet.ac.in
ME8097 NON DESTRUCTIVE
TESTING AND EVALUATION

2. UNIT V RADIOGRAPHY (RT)
1. Principle, interaction of X-Ray with matter,
2. imaging, film and film less techniques,
3. types and use of filters and screens,
4. geometric factors, Inverse square, law,
5. characteristics of films - graininess, density, speed, contrast,
6. characteristic curves, Penetrameters,
7. Exposure charts, Radiographic equivalence.
8. Fluoroscopy- Xero-Radiography,
9. Computed Radiography, Computed Tomography

3. RADIOGRAPHY: EXPOSURE CHARTS
Introduction
• X-ray exposure charts are individual to the x-ray machine,
intensifying screen, film and developing combination.
• An exposure chart for one x-ray machine cannot be transferred
to another machine even if it is identical.
• Exposure charts are important to:
– Provide consistent results.
– Reduce number of exposures (important for radiation safety
and cost).
– Allows direct comparison between films taken on different
dates in the same animal.

4. • When compiling an exposure chart as many variable as possible
should be kept constant:
– Film focal distance.
– Object film distance.
– Processing.
– Film type.
– Intensifying screen type.
– Use of grid.
– Line mains compensation.
• Several charts may be needed for different film/screen
combinations and different species.

5. Radiographic Equivalence Factors
 It is that factor by which the thickness of the material should be
multiplied in order to determine what thickness of a standard
material shall have the same attenuation.
 This may be used :
 a) To determine the practical thickness limits for radiation
sources for metals other than the standard materials, and
 b) To determine exposure factors for one metal from exposure
charts compiled for other metals.