martijneppenga / Monte_Carlo_radiation_transport

Monte Carlo simulation of radiative dose deposition

The fourth and final project of the computational physics course is about radiative dose deposition. Monte Carlo techniques are used to simulate the path of many 'photons', dropping dose and scattering as they travel.

Getting Started

In order to run the simulation, copy all the .py files in the repository to your working directory. Change the input constants in constants.py, save the file, then start the simulation from the simulation module, and use the results to do the processing, as follows:

import importlib
import simulation
import data_processing

importlib.reload(simulation)
results = simulation.start()
importlib.reload(data_processing)
data_processing.start(*results)

Or, simply run launcher.py which does all of the above steps.

Options for constants

The following inputs can be adjusted in constants.py

Simulation constants

• Nbins The number of bins in each direction. This constant decides what your resolution will be
• L The size of the volume in units of length in which the photon travel will take place.
• treshold The fraction of photon remaining at which it will undergo the "Terminate?" routine.
• p_term The probability of terminating a photon reaching a weight below threshold value

Material constants

• mu_a Absorption coefficient
• mu_s Scattering coefficient
• g Anisotropy of scattering
• n1 Refractive index inside volume
• n2 Refractive index outside volume and inside cavity

Beam properties

• N Number of photons to trace
• a Radius of the circular beam
• mode Type of beam. Options are "single" for a single beam pointing in the z-direction, or "multiple"
• nbps Number of beams per side in case "multiple" was chosen for mode

Cavity properties

• cavity Enables the cavity when set to 'True'
• cavcent Coordinates of the center of the cavity
• cavr Radius of the cavity

Tissue properties

• t_c Coordinates of the center of the tumor
• t_r Radius of the tumor
• spine_c Coordinates of the axis of the cylindrical spine
• spine_r Radius of the spine

Obtained results

The output of the simulation contains:

• A Matrix of Nbins x Nbins x Nbins, containing the energy absorped in each bin, in units of photon weights
• dose_t Total photons weights absorbed in tumor
• dose_spine Total photon weights absorbed in spine

Authors

• Martijn Eppenga
• Richard Faasse
• Cyrus Tirband