ECE532 Biomedical Optics © 1998 Steven L. Jacques, Scott A. Prahl Oregon Graduate Institute

Steady-State Monte Carlo

A minimal program, "mc321.c".

A simple program called "mc321.c" is listed here for compilation by the student. It is written in ANSI Standard C and should compile on any platform. Students will need a C compiler on their own computer.

The following pages discuss the various sections of "mc321.c":

• Introduction to the basic program
• Header statements
• Definitions of variables and arrays
• User settings for optical properties, etc.
• Launching photon
• Moving a photon through tissue
  • Photon hops to new position where photon-tissue interaction occurs
  • Photon drops some photon weight in local bin arrays due to absorption
  • Photon spins into new trajectory due to scattering
  • Terminating a photon by "roulette" method
• Save bin arrays as output file for graphical plotting
• Example figure produced by the program

Students are encouraged to modify the program. Some example modifications are listed:

• Launching a collimated narrow photon beam.
• Launching a collimated finite-diameter beam of uniform irradiance.

This minimal program as written does NOT consider an air/tissue surface or other mismatched boundaries. The program models an infinite unbounded medium with absorption and scattering properties.

The "mc321.c" program was used in writing the published report: S. L. Jacques: "Light distributions from point, line, and plane sources for photochemical reactions and fluorescence in turbid biological tissues," Photochem. Photobiol. 67:23-32, 1998.