tacweigh - tpcclib 0.7.8 © 2022 by Turku PET Centre
Add or remove the sample (time frame) weighting information to TAC file for
parameter estimations and curve fitting using formula (Mazoyer et al, 1986):
weight=(frame duration)^2 / (decay corrected trues in a frame)
TACs are assumed to be corrected for decay, and SIFs not corrected.
The relative weights are adjusted using a scan information file (SIF),
or TACs in the file (volume weighted average of all TACs or given TAC);
in the latter case the units in TAC file must be set correctly.
Usage: tacweigh [Options] tacfile [sif | tacname]
Existing weights are removed.
Weights are not calculated, but existing weights are printed on screen.
Return code is non-zero if data does not contain weights.
-wf | -wfd
With -wf Weights are based only on frame length or sampling interval.
With -wfd the late frames are given less weight by using formula:
weight=(frame duration)*exp(-t*ln(2)/halflife) (Thiele et al, 2008).
Isotope, for example C-11, in case it is not found inside SIF or TAC
file. Isotope is only needed with SIF, and with option -wfd.
Weights are moderated by limiting the ratio of maximum and minimum
weights to the given ratio (100 by default). Weights that are lower
than maximum/ratio are set to maximum/ratio. Enter zero to not
moderate the weights. Otherwise ratio must be larger than one.
SIF data based on TAC file is written in given file; cannot be used
if SIF is given as argument.
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.
Note that absolute weights cannot be calculated. Relative weights are
scaled so that average weight is 1.0 for frames that have weight above 0.
1. Mazoyer BM, Huesman RH, Budinger TF, Knittel BL. Dynamic PET data
analysis. J Comput Assist Tomogr 1986; 10:645-653.
2. Thiele F, Buchert R. Evaluation of non-uniform weighting in non-linear
regression for pharmacokinetic neuroreceptor modelling.
Nucl Med Commun. 2008; 29:179-188.
See also: sifcat, sifisot, taclist, imgweigh, tacframe, imghead, tacdecay
Keywords: TAC, SIF, modelling, weighting, fitting