The delta-volume method for 3-dimensional cobalt-60 dose calculations has been implemented on a VAX 11/780 computer. Dose is calculated as the sum of the primary, augmented first scatter and residual multiple scatter doses to each volume element. The first two components are calculated by 'ray-tracing' where density information along the photon paths are used to adjust the corresponding dose values in water. The multiple scatter dose is approximated by an empirical function. The present algorithm accounts for primary beam variations, external contours, internal inhomogeneities and backscatter effects in the ray-trace procedures. Comparisons of the calculated and measured exit-dose distribution provide a direct means to verify the implementation of a treatment plan. Extension to higher photon energy is straightforward.
|Title of host publication||Unknown Host Publication Title|
|Number of pages||5|
|State||Published - Dec 1 1984|