Computes projection matrix elements for VoxelsOnCartesianGrid images by using a Length of Intersection (LOI) model. More...

#include "stir/recon_buildblock/ProjMatrixByBinUsingRayTracing.h"

Inheritance diagram for stir::ProjMatrixByBinUsingRayTracing:

[legend]

Public Member Functions
	ProjMatrixByBinUsingRayTracing ()
	Default constructor (calls set_defaults())

void	set_up (const shared_ptr< const ProjDataInfo > &proj_data_info_ptr, const shared_ptr< const DiscretisedDensity< 3, float >> &density_info_ptr) override
	Stores all necessary geometric info. More...

ProjMatrixByBinUsingRayTracing *	clone () const override

If a cylindrical FOV or the whole image will be handled
bool	get_restrict_to_cylindrical_FOV () const

void	set_restrict_to_cylindrical_FOV (bool)

How many rays will be traced in tangential direction for one bin
int	get_num_tangential_LORs () const

void	set_num_tangential_LORs (int)

If interleaved sinogram coordinates are used or not.
bool	get_use_actual_detector_boundaries () const

void	set_use_actual_detector_boundaries (bool)

Which symmetries will be used
bool	get_do_symmetry_90degrees_min_phi () const

void	set_do_symmetry_90degrees_min_phi (bool)

bool	get_do_symmetry_180degrees_min_phi () const

void	set_do_symmetry_180degrees_min_phi (bool)

bool	get_do_symmetry_swap_segment () const

void	set_do_symmetry_swap_segment (bool)

bool	get_do_symmetry_swap_s () const

void	set_do_symmetry_swap_s (bool)

bool	get_do_symmetry_shift_z () const

void	set_do_symmetry_shift_z (bool)

Public Member Functions inherited from stir::RegisteredParsingObject< ProjMatrixByBinUsingRayTracing, ProjMatrixByBin, ProjMatrixByBin >
std::string	get_registered_name () const override
	Returns Derived::registered_name.

std::string	parameter_info () override
	Returns a string with all parameters and their values, in a form suitable for parsing again.

Public Member Functions inherited from stir::ProjMatrixByBin
const DataSymmetriesForBins *	get_symmetries_ptr () const
	get a pointer to an object encoding all symmetries that are used by this ProjMatrixByBin

const shared_ptr< DataSymmetriesForBins >	get_symmetries_sptr () const
	get a shared_ptr to an object encoding all symmetries that are used by this ProjMatrixByBin

void	get_proj_matrix_elems_for_one_bin (ProjMatrixElemsForOneBin &, const Bin &) const
	The main method for getting a row of the matrix. More...

void	enable_cache (const bool v=true)

void	store_only_basic_bins_in_cache (const bool v=true)

bool	is_cache_enabled () const

bool	does_cache_store_only_basic_bins () const

void	clear_cache () const
	Remove all elements from the cache.

Public Member Functions inherited from stir::ParsingObject
	ParsingObject (const ParsingObject &)

ParsingObject &	operator= (const ParsingObject &)

void	ask_parameters ()

bool	parse (std::istream &f)

bool	parse (const char *const filename)

Public Member Functions inherited from stir::TimedObject
void	reset_timers ()
	reset all timers kept by this object

void	stop_timers () const
	stop all timers kept by this object More...

void	start_timers (bool do_reset=false) const
	start all timers kept by this object More...

double	get_CPU_timer_value () const
	get current value of the CPU timer (since first use or last reset)

double	get_wall_clock_timer_value () const
	get current value of the wall-clock timer (since first use or last reset)

Static Public Attributes
static const char *const	registered_name = "Ray Tracing"
	Name which will be used when parsing a ProjMatrixByBin object.

Additional Inherited Members
Static Public Member Functions inherited from stir::RegisteredParsingObject< ProjMatrixByBinUsingRayTracing, ProjMatrixByBin, ProjMatrixByBin >
static ProjMatrixByBin *	read_from_stream (std::istream *)
	Construct a new object (of type Derived) by parsing the istream. More...

Static Public Member Functions inherited from stir::RegisteredObject< ProjMatrixByBin >
static ProjMatrixByBin *	read_registered_object (std::istream *in, const std::string &registered_name)
	Construct a new object (of a type derived from Root, its actual type determined by the registered_name parameter) by parsing the istream. More...

static ProjMatrixByBin *	ask_type_and_parameters ()
	ask the user for the type, and then calls read_registered_object(0, type) More...

static void	list_registered_names (std::ostream &stream)
	List all possible registered names to the stream. More...

Protected Types inherited from stir::RegisteredObject< ProjMatrixByBin >
typedef ProjMatrixByBin (	RootFactory) (std::istream *)
	The type of a root factory is a function, taking an istream* as argument, and returning a Root*.

typedef FactoryRegistry< std::string, RootFactory, interfile_less >	RegistryType
	The type of the registry.

Protected Member Functions inherited from stir::ProjMatrixByBin
	ProjMatrixByBin ()
	default ctor (calls set_defaults()) More...

Succeeded	get_cached_proj_matrix_elems_for_one_bin (ProjMatrixElemsForOneBin &) const
	The method that tries to get data from the cache. More...

void	cache_proj_matrix_elems_for_one_bin (const ProjMatrixElemsForOneBin &) const
	The method to store data in the cache.

Protected Member Functions inherited from stir::ParsingObject
virtual void	set_key_values ()
	This will be called before parsing or parameter_info is called. More...

Static Protected Member Functions inherited from stir::RegisteredObject< ProjMatrixByBin >
static RegistryType &	registry ()
	Static function returning the registry. More...

Protected Attributes inherited from stir::ProjMatrixByBin
shared_ptr< DataSymmetriesForBins >	symmetries_sptr

bool	cache_disabled

bool	cache_stores_only_basic_bins

bool	tof_enabled
	If activated TOF reconstruction will be performed.

shared_ptr< const VoxelsOnCartesianGrid< float > >	image_info_sptr
	We need a local copy of the discretised density in order to find the cartesian coordinates of each voxel.

shared_ptr< const ProjDataInfo >	proj_data_info_sptr
	We need a local copy of the proj_data_info to get the integration boundaries and RayTracing.

Protected Attributes inherited from stir::ParsingObject
KeyParser	parser

Detailed Description

Computes projection matrix elements for VoxelsOnCartesianGrid images by using a Length of Intersection (LOI) model.

Currently, the LOIs are divided by voxel_size.x(), unless NEWSCALE is #defined during compilation time of ProjMatrixByBinUsingRayTracing.cxx.

It is possible to use multiple LORs in tangential direction. The result will then be the average of the various contributions. Currently all these LORs are parallel. For a very high number of LORs, the result approximates a strip integral (in tangential direction).

If the z voxel size is exactly twice the sampling in axial direction, 2 or 3 LORs are used, to avoid missing voxels. (TODOdoc describe how).

If use_actual_detector_boundaries is set (currently only possible for non-arccorrected data, without mashing and/or axial compression), the detectors are assumed to be on a cylinder. If only a single LOR in tangential direction is used for ray tracing, the centre of those detectors is used, which is slightly different from the 'usual' LOR (due to interleaving of the sinogram). When multiple LORs are used, the actual detector sizes are used, such that the resulting strip is twice as wide.

It is possible to use a cylindrical or cuboid FOV (in the latter case it is going to be square in transaxial direction). In both cases, the FOV is slightly 'inside' the image (i.e. it is about 1 voxel at each side smaller than the maximum possible).

Symmetries

For the azimuthal angle phi, the following angles are symmetry related for a square grid: {phi, 180-phi, 90-phi, 90+phi}. The boolean parameters "do symmetry 90degrees min phi", "do symmetry 180degrees min phi" allow to select if all 4 angles should be considered as related.

Enabling more symmetries (from DataSymmetriesForBins_PET_CartesianGrid) means that less memory is needed to store the matrix (when caching), less time to compute it, but using the matrix might be slightly slower. By default, as many symmetries as possible are enabled.

Parsing parameters

The following parameters can be set (default values are indicated):

Ray Tracing Matrix Parameters :=
; any parameters appropriate for class ProjMatrixByBin
restrict to cylindrical FOV := 1
number of rays in tangential direction to trace for each bin := 1
use actual detector boundaries := 0
do symmetry 90degrees min phi := 1
do symmetry 180degrees min phi := 1
do_symmetry_swap_segment := 1
do_symmetry_swap_s := 1
do_symmetry_shift_z := 1
End Ray Tracing Matrix Parameters :=

Implementation details

The implementation uses RayTraceVoxelsOnCartesianGrid().

Warning: After calling any of the set functions or parsing, you have to call setup(), otherwise using the matrix will result in a call to error().; Only appropriate for VoxelsOnCartesianGrid type of images (otherwise error() will be called).; Care should be taken to select the number of rays in tangential direction such that the sampling is at least as small as the x,y voxel sizes.; Current implementation assumes that z voxel size is either smaller than or exactly twice the sampling in axial direction of the segments.

Bug:: Currently, strange things happen if the z voxel size is not exactly equal to half the ring spacing of the scanner.

Member Function Documentation

◆ set_up()

void stir::ProjMatrixByBinUsingRayTracing::set_up	(	const shared_ptr< const ProjDataInfo > &	proj_data_info_ptr,
		const shared_ptr< const DiscretisedDensity< 3, float >> &	density_info_ptr
	)

overridevirtual

Stores all necessary geometric info.

Note that the density_info_ptr is not stored in this object. It's only used to get some info on sizes etc.

Implements stir::ProjMatrixByBin.

References stir::error(), stir::info(), and stir::warning().

The documentation for this class was generated from the following files:

/home/sirfuser/devel/STIRdistrib/STIR/src/include/stir/recon_buildblock/ProjMatrixByBinUsingRayTracing.h
/home/sirfuser/devel/STIRdistrib/STIR/src/recon_buildblock/ProjMatrixByBinUsingRayTracing.cxx

Public Member Functions

Static Public Attributes

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ set_up()