fit_feng 1.4.1 © 2001-2011 by Turku PET Centre
Non-linear fitting of the model suggested by Feng et al (1) to PET plasma
time-activity curves.
Function:
when t<=tau : y(t) = 0
when t>tau: y(t) = (p1*(t-tau)-p3-p5)*exp(p2*(t-tau))
+ p3*exp(p4*(t-tau)) + p5*exp(p6*(t-tau))
Usage: fit_feng [Options] <Datafile> <FIT file>
Options:
-integ[ral]
Given datafile represents the integral of fitted function
-wf
Weight by sampling interval
-ext[ended] or -simpl[ified]
Apply extended model (one extra exponential term with two more
parameters) or simplified model (p5 and p6 fixed to zero)
-ss
Function approaches steady level; last exponent term is a constant,
i.e. either p6 or p8 is 0
-delay=<<value>|mean|median>
Delay time (tau) is constrained to specified value or to mean or median
of all TACs
-fast or -safe
Speed up the fitting but increase the chance of failure, or
increase the reliability at the cost of computing time
-cst=<Sample time>
Earlier samples are not used in setting parameter constraints
(but all samples are used in fitting); 0 by default
-fit=<Filename>
Fitted TACs are written in DFT format
-svg=<Filename>
Fitted and measured TACs are plotted in specified SVG file
-h or --help
Print this message and exit
--version or --build
Print software build information and exit
--silent
Program works silently, printing only error and warning messages
--verbose
Program prints more information about what it is doing
Datafile can be any DFT file (2) which can include weights.
Program writes the fit start and end times, nr of points, WSS/n,
and parameters (p1, p2, p3, p4, p5, p6, tau) of the fitted function
to the FIT file (3).
Example 1: Fit function to plasma TAC and compute fitted curve
between 0 and 60 min at 0.1 min intervals:
fit_feng p455ap.kbq p455ap.fit
fit2dat -c=0,60,0.1 p455ap.fit p455ap_new.kbq
Example 2: Fit function to plasma TAC and plot fitted and measured TACs
in SVG format:
fit_feng -svg=p455apfit.svg p455ap.kbq p455ap.fit
References:
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.
2.
http://www.turkupetcentre.net/analysis/doc/format_dft.html
3.
http://www.turkupetcentre.net/analysis/doc/format_fit.html
See also:
fit2dat,
fit_sinf,
fit_exp,
fit_ratf,
fit_hiad
Keywords: DFT, input, modelling, simulation
This program comes with ABSOLUTELY NO WARRANTY. This is free software, and
you are welcome to redistribute it under GNU General Public License.
