Determination of total activity and its distribution in cathetron source pencils

High intensity remote-controlled afterloading devices such as Cathetron, employ tiny source elements which facilitate free movement through the curvature of the guide tubes. As the activities involved are in the curie level and a number of sources are assembled together in the form of a pencil, conventional methods cannot be employed for determining the activity of individual sources. This paper deals with the determination of the total activity of a source pencil from the measured exposure rate and an autoradiographic method used to determine the activity of individual sources.