Abstract:
Garareagraphy which is a part of radiography, is one of the important and effective methods in nondestructive tes%ing and determination of exposure time in gamrnagraghy has a special importance from the point of view ofcradiographic results. The aim of this study is to evaluate the methods of expssiase time determination (ETD) then, after choosing the most reliable method, to construct ETD tables for workers in this field, There are several methods used in determination of exposme time in gammagraphy. In this study tiexposure charte method which is an experimental method and a theoretical approach is used, The theoretical method is modified by using build up factors and improved as an "alternativew method, The reason for the choice of these methods is that they are very appropriate for computer analysis so that a realistic comparison of the methods could be done, The study can be divided into two main parts, In the first step, all ETD methods were computerized for several gamma sources, films, film densities, arid materials and the results were compared. Then, in the next step, which is the experimental past of the study, some radiographs were taken with aBOUN%he methods by using a 30 Curies Cobalt-60 source and the methsd giving the best result was determined, The results obtained from the computer analysis and experiments showed that the alternative method has given the best radiographs among the other ETD methods.
