fit_feng - tpcclib 0.8.0 © 2023 by Turku PET Centre
Non-linear fitting of the exponential based function suggested by
Feng et al (1993) to the PET plasma or blood time-activity curve (TAC).
when t<=dt : f(t) = 0
when t>dt : f(t) = (p1*(t-dt)-p3-p5)*exp(p2*(t-dt))
+ p3*exp(p4*(t-dt)) + p5*exp(p6*(t-dt))
Usage: fit_feng [Options] tacfile [parfile]
Specify the constraints for function parameters;
This file with default values can be created by giving this
option as the only command-line argument to this program.
Without file name the default values are printed on screen.
Given datafile contains the AUC of TAC as function of time.
Weight by sampling interval.
The nr of exponential functions; A=determined automatically.
Default is 3; changing the default may lead to a bad fit.
Function approaches steady level; last exponent term is a constant,
i.e. either p6 or p8 is 0.
Delay time (dt) is constrained to specified value (>=0).
Error is returned if MRL check is not passed.
-fast or -safe
Speed up the fitting but increase the chance of failure, or
increase the reliability at the cost of computing time
Fitted parameters are also written in result file format.
Fitted and measured TACs are plotted in specified SVG file.
Initial part of fitted and measured TACs are plotted in SVG file
Lower part of fitted and measured TACs are plotted in SVG file
Fitted TACs are written in TAC format.
Display usage information on standard output and exit.
Display version and compile information on standard output and exit.
-d[n], --debug[=n], --verbose[=n]
Set the level (n) of debugging messages and listings.
Suppress displaying normal results on standard output.
Suppress displaying anything except errors.
TAC file must contain at least two columns, sample times in the first,
and concentrations of TACs in the following columns.
To obtain a good fit, TAC should be corrected for physical decay and any
Function parameters (p1, ..., dt) will be written in the parfile.
1. Feng D, Huang S-C, Wang X. Models for computer simulation studies of input
functions for tracer kinetic modeling with positron emission tomography.
Int J Biomed Comput. 1993;32:95-110.
See also: fit2dat, fit_sinf, fit_exp, fit_dexp, fit_ratf, extrapol
Keywords: curve fitting, input, modelling, simulation