Radiation measurements utilising collimated source and detector systems inv
ariably result in a target volume described by the overlap of their fields
of view. When these collimators are cylindrical, this is derived from the v
olume of intersection of two cones. In general, analysis of this volume doe
s not lend itself to a direct analytical process. Here, numerical methods o
f estimating the common volume of two intersecting right cones are presente
d. These include methods which employ, (a) a sequential scanning of an elem
ental volume with a predetermined size across a defined space containing th
e volume of interest and (b) a Monte Carlo technique. The accuracy obtainab
le and the execution time in the first type of algorithm depend on the size
of the elemental volume (bin-size). On the other hand, these two parameter
s are independent of the bin-size but dependent on the number of histories
sampled, for the Monte Carlo technique. At 0 degrees angle of inclination,
where an analytical estimation is easily obtained, the three algorithms con
sidered here resulted in values with a precision better than 0.1% when comp
ared to the analytically calculated one. (C) 2000 Elsevier Science Ltd. All
rights reserved.