The Research on the Inverse Square Law in Diagnostic Radiography

Abstract

The inverse square law is considered to be valid in measuring characteristic curves virtually governed by this law. But this law is not perfectly applicable to the tube voltage range for conventional radiography. In inverse square law, x-ray intensity is proportional to 1/rm (r means source detector distance)and the value of m is usually 2.0. In the report, the value of m with the ionization chamber and the fluorescent detector is studied.
The value of m measured by the ionization chamber detector changes from 2.1 to 2.0 when the tube voltage alters from 60 kVp to 140 kVp. However, the value of m obtained by the fluorescent screen detector remains at 2.1 in the same tube voltage range