Voxel Objects

A voxel object is how the program represents a material in the phantom. By utilising the voxel object, we can create different shapes of within your phantom.

voxel_object

Purpose

The voxel object is a class that is used to represent a material in the phantom. It contains a function to determine if a point is inside the object or not and a function to determine the linear attenuation coefficient of the material.

Properties

All of these properties are immutable, therefore they cannot be changed after the object is created.

is_in_object

(function) A function that takes a set of points (x, y, z) and returns a list of logical values indicating if the point is inside the object or not.

material

(material_attenuation) The material of the object.

get_mu

(function) A function that takes an energy and returns the linear attenuation coefficient of the material at that energy.

Functions

voxel_object(is_in_object, material)

Returns a voxel object with the given is_in_object function and material. get_mu is an anonymous function that returns the linear attenuation coefficient of the material at the given energy.

Parameters:

  • is_in_object (function) – A function that takes a set of points (x, y, z) and returns a list of logical values indicating if the point is inside the object or not.

  • material (material_attenuation) – The material of the object.

Returns:

obj - An instance of the voxel object class.

Return type:

voxel_object

Functions to create voxel objects

There are several functions that can be used to create a voxel object. These are:

voxel_cylinder(centre, radius, width, material)

Returns a voxel object that represents a cylinder with the given centre, radius, width and material.

Parameters:

  • centre (1x3 double) – The centre of the cylinder.

  • radius (double) – The radius of the cylinder.

  • width (double) – The width of the cylinder.

  • material (material_attenuation) – The material of the cylinder.

Returns:

obj - An instance of the voxel object class.

Return type:

voxel_object

voxel_cube(cube_centre, cube_size, material)

Returns a voxel object that represents a cube with the given cube_centre, cube_size and material.

Parameters:

  • cube_centre (1x3 double) – The centre of the cube.

  • cube_size (double) – The size of the cube.

  • material (material_attenuation) – The material of the cube.

Returns:

obj - An instance of the voxel object class.

Return type:

voxel_object

voxel_ellipsoid(centre, a, b, c, material)

Returns a voxel object that represents an ellipsoid with the given centre, a, b, c and material.

Parameters:

  • centre (1x3 double) – The centre of the ellipsoid.

  • a (double) – The semi-axis of the ellipsoid in the x-direction.

  • b (double) – The semi-axis of the ellipsoid in the y-direction.

  • c (double) – The semi-axis of the ellipsoid in the z-direction.

  • material (material_attenuation) – The material of the ellipsoid.

Returns:

obj - An instance of the voxel object class.

Return type:

voxel_object

voxel_ellipsoid_rotated(centre, a, b, c, angle, material)

Returns a voxel object that represents an ellipsoid rotated about the z-axis with the given centre, a, b, c, angle and material.

Parameters:

  • centre (1x3 double) – The centre of the ellipsoid.

  • a (double) – The semi-axis of the ellipsoid in the x-direction.

  • b (double) – The semi-axis of the ellipsoid in the y-direction.

  • c (double) – The semi-axis of the ellipsoid in the z-direction.

  • angle (double) – The angle of rotation about the z-axis.

  • material (material_attenuation) – The material of the ellipsoid.

Returns:

obj - An instance of the voxel object class.

Return type:

voxel_object