halflife.c File Reference

Functions for processing isotope half-life and decay correction. More...

#include "libtpcmisc.h"

Go to the source code of this file.

Functions
char *	hlIsotopeCode (int isotope)
double	hlFromIsotope (char *isocode)
double	hl2lambda (double halflife)
double	hlLambda2factor (double lambda, double frametime, double framedur)
float	hlLambda2factor_float (float lambda, float frametime, float framedur)
char *	hlCorrectIsotopeCode (char *isocode)
int	hlIsotopeFromHalflife (double halflife)

Detailed Description

Functions for processing isotope half-life and decay correction.

Author

Vesa Oikonen, Kaisa Liukko

See also

branch.c

Definition in file halflife.c.

Function Documentation

hl2lambda()

double hl2lambda

(

double

halflife

)

Calculates the isotope lambda from specified halflife.

Parameters

halflife

halflife time value

Returns

A negative value is returned in case of error.

Definition at line 84 of file halflife.c.

                                  {
  if(halflife>0.0) return(M_LN2/halflife); else return(-1.0); // M_LN2=log(2.0)
}

Referenced by atnMake(), dftDecayCorrection(), img2sif(), imgDecayCorrection(), imgSetDecayCorrFactors(), and noiseSD4Simulation().

hlCorrectIsotopeCode()

char * hlCorrectIsotopeCode

(

char *

isocode

)

Check that isotope code, e.g. F-18, is in valid format, containing '-' and in this order. Returns the correct isotope code.

Parameters

isocode

Pointer to string "C-11", "11c" etc; contents of this string is not changed, and this is not returned in any case

Returns

pointer to correct isotope code, and NULL if it was not valid and could not be corrected.

Definition at line 141 of file halflife.c.

                                          {
  int i, ok=0, n, mass_nr=0, ic_mass_nr=0;
  char *cptr, atom[3], ic_atom[3];
 
  /* Check, if isocode can be found in the list */
  i=ok=0;
  while(isotope_code[i]!=0) {
    if(strcasecmp(isotope_code[i], isocode)==0) {
      ok=1;
  break;
    }
    i++;
  }
  if(ok==1) return(isotope_code[i]);
 
  /* Try to figure out what it is */
  /* Separate the atom name and mass number */
  n=strcspn(isocode, "-1234567890");
  if(n>2) { /* cannot be */
    return(NULL);
  } else if(n>0) { /* start with atom name */
    strncpy(atom, isocode, n); atom[n]=(char)0;
    mass_nr=atoi(isocode+n); if(mass_nr<0) mass_nr=-mass_nr;
  } else { /* starts with mass number */
    mass_nr=atoi(isocode);
    cptr=isocode; while(isdigit((int)cptr[0])) cptr++;
    if(strlen(cptr)>2) return(NULL);
    strcpy(atom, cptr); 
  }
  /* Check if it matches any of the listed isotopes */
  i=ok=0;
  while(isotope_code[i]!=0) {
    /* Separate the atom name and mass number from the listed isotope */
    n=strcspn(isotope_code[i], "-1234567890");
    strncpy(ic_atom, isotope_code[i], n); ic_atom[n]=(char)0;
    ic_mass_nr=atoi(isotope_code[i]+n+1);
    /* Check the atom name */
    if(strcasecmp(ic_atom, atom)!=0) {i++; continue;}
    /* Check the mass number, if given */
    if(mass_nr>0 && ic_mass_nr!=mass_nr) {i++; continue;}
    /* Match was found! */
    ok=1; break;
  }
  if(ok==1) return(isotope_code[i]); else return(NULL);
}

Referenced by hlFromIsotope(), and sif2dft().

hlFromIsotope()

double hlFromIsotope

(

char *

isocode

)

Identify the isotope from the specified isotope code string and return the halflife (min). This function checks the validity of the isotope string using hlCorrectIsotopeCode(), but does not change it in any way.

Returns

A negative value is returned in case of error.

Parameters

isocode

Pointer to string "C-11", "18f" etc. This argument is not changed.

Definition at line 55 of file halflife.c.

  {
  char *corrected_isocode;
  int i = 0;
  int ok = 0;
 
  /* Validate the isotope string */
  corrected_isocode=hlCorrectIsotopeCode(isocode);
  if(corrected_isocode==NULL) return(-1.0);
 
  /* Determine the isotope and return the half-life */
  while(isotope_code[i]!=0) {
    if(strcmp(isotope_code[i], corrected_isocode)==0) {ok=1; break;}
    i++;
  }
  if(ok==1) return(isotope_halflife[i]);
  else return(-2.0);
} 

Referenced by dftDecayCorrection(), imgReadAnalyzeHeader(), imgReadModelingData(), imgReadNiftiHeader(), noiseSD4SimulationFromDFT(), and sif2img().

hlIsotopeCode()

char * hlIsotopeCode

(

int

isotope

)

Isotope code as a string, based on isotope list number.

Parameters

isotope

index of PET isotope in the list in halflife.c

Returns

pointer to static string or "unknown".

Definition at line 36 of file halflife.c.

                                 {
  static char unknown_isotope[]="unknown";
  int n=0;
  
  while(isotope_code[n]!=0) n++;
  if(isotope<0 || isotope>n-1) return(unknown_isotope);
  else return(isotope_code[isotope]);
}

Referenced by dftDecayCorrection(), and imgIsotope().

hlIsotopeFromHalflife()

int hlIsotopeFromHalflife

(

double

halflife

)

Identify the isotope based on its halflife (in minutes).

Parameters

halflife

Half-life in minutes

Returns

the isotope list number, or negative value if not identified.

Definition at line 195 of file halflife.c.

                                           {
  int i=0, ok=0;
  if(halflife<=0.01) return(-1);
  while(isotope_halflife[i]>0.0) {
    if( fabs(halflife/isotope_halflife[i]-1.0)<0.05 ) {ok=1; break;}
    i++;
  }
  if(ok==1) return(i);
  else return(-2.0);
}

Referenced by dftDecayCorrection(), imgBranchingCorrection(), and imgIsotope().

hlLambda2factor()

double hlLambda2factor	(	double	lambda,
		double	frametime,
		double	framedur )

Calculate the decay correction factor for specified isotope lambda.

Parameters

lambda	Negative lambda removes decay correction
frametime	Frame start time, or mid time if framedur<=0
framedur	If unknown, set <0 and give mid time for frametime

Returns

A negative value is returned in case of error.

Definition at line 98 of file halflife.c.

                                                                         {
  double cf, ff;
 
  if(frametime<0) return(-1.0);
  cf=exp(lambda*frametime);
  if(framedur>1.0E-5) {
    ff=fabs(lambda)*framedur/(1.0-exp(-fabs(lambda)*framedur));
    if(lambda<0.0) cf/=ff; else cf*=ff;
  }
  return(cf);
}

Referenced by atnMake(), dftDecayCorrection(), img2sif(), and noiseSD4Simulation().

hlLambda2factor_float()

float hlLambda2factor_float	(	float	lambda,
		float	frametime,
		float	framedur )

Calculate the decay correction factor for specified isotope lambda. Version for floats (mainly image data).

Parameters

lambda	Negative lambda removes decay correction
frametime	Frame start time, or mid time if framedur<=0
framedur	If unknown, set <0 and give mid time for frametime

Returns

A negative value is returned in case of error.

Definition at line 118 of file halflife.c.

                                                                           {
  float cf, ff;
 
  if(frametime<0) return(-1.0);
  cf=exp(lambda*frametime);
  if(framedur>1.0E-5) {
    ff=fabs(lambda)*framedur/(1.0-exp(-fabs(lambda)*framedur));
    if(lambda<0.0) cf/=ff; else cf*=ff;
  }
  return(cf);
}  

Referenced by imgDecayCorrection(), and imgSetDecayCorrFactors().