DFT TAC file format
DFT is a multi-purpose ASCII data file format for regional tissue time-activity curves (TTACs), blood or plasma TACs (PTACs, BTACs), and fractions of authentic tracer and its metabolites in plasma. Analysis tools developed in TPC can read DFT files (as well as a few other TAC formats, including PMOD CRV files). Tools for processing TAC files in DFT and other formats are downloadable in TPC download pages.
Datafile can contain one or more lines, which represent the separate samples (time points); lines end with line feed character. First one or two columns contain the sample time or frame start and end times, respectively. The next one or more columns contain the numerical sample values measured at the specified time. Columns are separated with any number of spaces or with a single tabulator (TSV format). File must contain only a single type of column separator.
Missing values or strings are represented with a single “.” (period), or in TSV format also an empty field represents missing value. Data column widths can be varied.
There are no restrictions for the name of file, but for clarity, extensions
.dft are recommended.
Four (4) title lines include information about names and sizes of regions and the measurement units.
As an identifier of file type, DFT files must start with string
After the identifier, the first title line contains the names of regions.
The second title line contains an identification string for the study, e.g. study number, which may be maximally 8 characters long. Following that, hemisphere or other secondary name for each (region) curve must be specified (specified as missing, if necessary).
The third title line contains the unit of measured numerical values
kBq/mL), followed by the planes (slices) where regions were drawn, or
other preferred type of description for the regions.
If spaces are used as column separator, the name fields obviously cannot contain any space characters; additionally the name fields should be maximally 6 characters long.
Fourth title line starts with the string “Times”, if frame start and end times are stored
(PET data), or “Time”, if only sample measurement times (plasma data) or mid times of PET frame
After that, time unit is provided in parenthesis, as
(s). And after that, the volumes of regions in units mm3 (= uL). Alternatively, strings
Time can be replaced by
Distance, and the units with strings
these are mainly used for technical purposes, e.g. in FWHM determination.
Columns which have been named as
weight are not processed as other TAC columns, but
are considered to contain relational weights for different time frames in model calculations and
in fitting of mathematical functions to data.
All programs must be able to read also files with no title lines, containing only sample time (or mid time of PET frame) and the numerical values (usually blood or plasma data, or parent fractions). In this case, programs should assume that times are minutes, unless units are given as comments.
File name extension
.kbq can be used to specify that radioactivity concentrations
are in units kBq/mL.
TAC files may contain comment lines starting with character ‘#’. These lines may also contain useful, or outdated, information on data units etc. In bash the comment lines can be removed with command:
sed '/^#/ d' < input.dat > output.dat
, or using program rmcmnts.
It is recommended, that all programs preserve old comment lines.
DFT file containing frame start and end times, with spaces as column separator:
DFT putam putam cereb exam0001 dx sin . kBq/ml pl18 pl18 pl29 Times (min) 675.2 712.8 9167.1 0.00 0.25 0.00e+00 -9.18e-03 2.98e-04 0.25 0.50 1.24e+00 1.11e+00 1.43e+00 0.50 0.75 4.68e+00 4.71e+00 5.22e+00 0.75 1.00 1.21e+01 1.15e+01 9.87e+00 1.00 1.50 1.89e+01 1.97e+01 1.03e+01 1.50 2.00 2.12e+01 2.56e+01 9.36e+00 2.00 3.00 2.45e+01 2.87e+01 8.69e+00 3.00 4.00 2.37e+01 2.67e+01 8.57e+00 4.00 5.00 2.68e+01 2.92e+01 6.99e+00 5.00 10.0 2.56e+01 . 7.05e+00 10.0 15.0 2.66e+01 2.80e+01 6.54e+00 # Example data for testing purposes
The same data with mid frame times, and tabulators as column separator:
DFT1 putam putam cereb exam0001 dx sin . kBq/mL pl18 pl18 pl29 Time (min) 6.752000e+02 7.128000e+02 9.167100e+03 0.125 0.00e+00 -9.18e-03 2.98e-04 0.375 1.24e+00 1.11e+00 1.43e+00 0.625 4.68e+00 4.71e+00 5.22e+00 0.875 1.21e+01 1.15e+01 9.87e+00 1.250 1.89e+01 1.97e+01 1.03e+01 1.750 2.12e+01 2.56e+01 9.36e+00 2.500 2.45e+01 2.87e+01 8.69e+00 3.500 2.37e+01 2.67e+01 8.57e+00 4.500 2.68e+01 2.92e+01 6.99e+00 7.500 2.56e+01 . 7.05e+00 12.500 2.66e+01 2.80e+01 6.54e+00 # Example data for testing purposes
Plasma and blood data is typically stored in the simple format. As an example, the plasma TAC, based on arterialized venous blood sampling, in a [18F]FDG PET study is given below in this simple format:
# Injection time: 10.05.2019 10:12:58 # Isotope: F-18 # Activity units: kBq/mL # Time units: min 0.333 3.222 0.850 33.467 1.233 19.928 1.667 16.322 2.050 14.923 3.250 12.470 5.367 9.910 9.117 6.685 19.000 3.071 24.367 2.277 29.083 1.753 34.017 1.399 49.300 0.725 69.100 0.455 82.967 0.354
- CRV format
- FIT TAC file format
- Result format
- ANC format
- Units of radioactivity in PET data
- Radioactivity measurement of blood samples
- PET data
- Simulation of PET time frames
- Plotting TACs
Updated at: 2019-12-21
Created at: 2007-01-10
Written by: Vesa Oikonen