rayTracing

matRad_rayTracing(stfElement, ct, V, rot_coordsV, lateralCutoff)

matRad visualization of two-dimensional dose distributions on ct including segmentation

call

[radDepthV, radDepthCube] = matRad_rayTracing(stf,ct,V,rot_coordsV,lateralCutoff)

Input:

  • stfElement – matRad steering information struct of single(!) beam

  • ct – ct cube

  • V – linear voxel indices e.g. of voxels inside patient.

  • rot_coordsV coordinates in beams eye view inside the patient

  • lateralCutoff – lateral cut off used for ray tracing (optional)

matRad_siddonRayTracer(isocenterCube, resolution, sourcePoint, targetPoint, cubes)

siddon ray tracing through 3D cube to calculate the radiological depth according to Siddon 1985 Medical Physics. The raytracer expects the isocenter in cube coordinates!

call

[alphas,l,rho,d12,vis] = matRad_siddonRayTracer(isocenter, …

resolution, … sourcePoint, … targetPoint, … cubes)

Input:

  • isocenterCube – isocenter in cube coordinates [mm]

  • resolution – resolution of the cubes [mm/voxel]

  • sourcePoint – source point of ray tracing

  • targetPoint – target point of ray tracing

  • cubes – cell array of cubes for ray tracing (it is possible to pass multiple cubes for ray tracing to save computation time)

Output:

  • alphas – relative distance between start and endpoint for the intersections with the cube

  • l – lengths of intersections with cubes

  • rho – densities extracted from cubes

  • d12 – distance between start and endpoint of ray tracing

  • ix – indices of hit voxels

References

[1] http://www.ncbi.nlm.nih.gov/pubmed/4000088

Copyright 2015-2026 the matRad development team.

This file is part of the matRad project. It is subject to the license terms in the LICENSE file found in the top-level directory of this distribution and at https://github.com/e0404/matRad/LICENSE.md. No part of the matRad project, including this file, may be copied, modified, propagated, or distributed except according to the terms contained in the LICENSE file.

class matRad_RayTracerSiddon(cubes, grid)

Bases: matRad_RayTracer

matRad_RayTracerSiddon Ray tracer using Siddon’s algorithm

Implements ray tracing through a CT volume using Siddon’s algorithm, which analytically computes the exact intersection lengths of a ray with each voxel by tracking parametric alpha values at which the ray crosses each set of parallel CT planes (x, y, z).

This class overrides traceRays() from matRad_RayTracer with a vectorized implementation that handles multiple rays simultaneously, significantly improving performance over the default loop.

References:

Siddon RL (1985), “Fast calculation of the exact radiological path for a three-dimensional CT array”, Med. Phys. 12(2):252-5.

Usage example:

tracer = matRad_RayTracerSiddon(cubes, grid); [alphas, l, rho, d12, ix] = tracer.traceRays(isocenter, sourcePoints, targetPoints);

Copyright 2026 the matRad development team.

This file is part of the matRad project. It is subject to the license terms in the LICENSE file found in the top-level directory of this distribution and at https://github.com/e0404/matRad/LICENSE.md. No part of the matRad project, including this file, may be copied, modified, propagated, or distributed except according to the terms contained in the LICENSE file.

Property Summary
vectorized = true

Uses vectorization instead of looping through rays

Method Summary
traceRay(this, isocenter, sourcePoint, targetPoint)
traceRays(this, isocenter, sourcePoints, targetPoints)
class matRad_RayTracer(cubes, grid)

Bases: handle

matRad_RayTracer Base class for ray tracing through a patient CT volume

This class provides the infrastructure for ray tracing in beam’s-eye-view (BEV) coordinates to compute radiological depths along rays from a radiation source through a patient CT grid.

Subclasses must implement the abstract method:
traceRay() - trace a single ray and return path segment lengths,

density values, and intersected voxel indices

Subclasses can optionally override:
traceRays() - trace multiple rays in a vectorized or otherwise accelerated manner

(default: loop over traceRay)

Usage example:

tracer = matRad_SomeRayTracerSubclass(cubes, grid); [radDepthsV, radDepthCube] = tracer.traceCube(stfElement, V);

Copyright 2026 the matRad development team.

This file is part of the matRad project. It is subject to the license terms in the LICENSE file found in the top-level directory of this distribution and at https://github.com/e0404/matRad/LICENSE.md. No part of the matRad project, including this file, may be copied, modified, propagated, or distributed except according to the terms contained in the LICENSE file.

matRad_RayTracer Construct a ray tracer instance cubes - cell array of density/material cubes to trace through grid - CT grid struct with fields x, y, z and resolution

Property Summary
lateralCutOff
forcePrecision = []

override precision (double or single), otherwise inherited

enableGPU = false

whether to use GPU arrays for ray tracing (if supported by subclass implementation)

Method Summary
traceRays(this, isocenter, sourcePoints, targetPoints)
traceRay(this, isocenter, sourcePoint, targetPoint)
traceCube(this, stfElement, voxelIndices, rotCoordsV)