CONV--convolution for responses to a finite diameter photon beam incident on multi-layered tissues.

A convolution program (CONV) solving responses to a collimated finite diameter photon beam perpendicularly incident on a multi-layered tissue has been coded in ANSI Standard C, hence, the program can be executed on various computers. The program, employing an extended trapezoidal rule for integration, convolves the responses to an infinitely narrow photon beam computed by a companion program (MCML). Dynamic data allocation is used for CONV as well as MCML, therefore, the number of tissue layers and grid elements of the grid system can be varied at run time. The potential error due to not scoring the first photon-tissue interactions separately is illustrated. The program, including the source code, has been in the public domain since 1992 and can be downloaded from the web site at http:(/)/biomed.tamu.edu/-lw.