File format of Allogg ABSS on-line detector raw data (Allogg2)
This document applies to our second generation Allogg device used with software developed by Allogg. The first generation Allogg device is used with in-house developed software and it produces a different file format.
The data collected using the Allogg ABSS (Allogg AB, Mariefred, Sweden, http://www.allogg.se/) on-line detectors ("blood pumps") is saved in ASCII files with extension *.txt. The format is mainly specified by the manufacturer of the device, except for the additional header line containing the background radiation level (cps) as the first line; this line is written by in-house programs.
Example of an Allogg raw data file:
//Average background counts 03/02/2010 : 2.9 //Heading System ID: ABSS09282 User name: hr+ Run number: is731dy1 Patient ID: 090675 HalfTime: 2.05 Tube length: Pump speed: DeadTimeSingles: 2.0E-6 DeadTimeCoincidents: 2.0E-6 DiscriminatorSingles: 130 DiscriminatorCoincidents: 280 EffectivitySingles: 3.483992636336913 EffectivityCoincidents: 0.4276085411957362 //Data Absolute time Time after start [s] Singles [cnt] Coincidents [cnt] Singles count rate [kBq/ml] Coincidents count rate [kBq/ml] Singles count rate DTC [kBq/ml] Coincidents count rate DTC [kBq/ml] Singles DTC&decay [kBq/ml] Coincidents DTC&decay [kBq/ml] 2010-05-17 12:31:37 0.0 6 4 0.04872721840822661 0.2646739619196592 0.04872738624114015 0.2646789137181051 0.04872738624114015 0.2646789137181051 2010-05-17 12:31:38 1.0 3 1 0.024363609204113304 0.0661684904799148 0.024363651162269427 0.06616879996297508 0.024501336278680105 0.06654273648279217 2010-05-17 12:31:39 2.0 8 4 0.06496962454430213 0.2646739619196592 0.06496992291426876 0.2646789137181051 0.06570632056398783 0.26767890080827605 ...
Calibration of data
Each measurement line is calibrated to units kBq/ml by following this procedure. Note that this does not contain correction for physical decay or dispersion. Normally, absscal (or its old version blo2kbq) can be used for this purpose.
- Take the value of coincidents counts on 4th data column
- Divide it by measurement duration in seconds (difference of times on column 2 in seconds)
- If the background activity was specified in the header lines, subtract it from counts-per-sec value (outcome of the previous step)
- Read the two calibration coefficients from
calibration coefficient file:
- selected detector specific detector-to-gamma counter calibration coefficient: “pump4(HRRT)”
- read also the last column, gamma counter-to-pet coefficient, which is common to all on-line detectors
- select calibration that is made just before or on the same day as the blood measurement
- Multiply the two calibration coefficients with each other
- Divide the calibration coefficient by the branching ratio of the radioactive label isotope (isotope can be identified based on halftime in the headers)
- Multiply the count-per-second value from step #3 by the combined calibration coefficient
- Correct the data for physical decay to the zero time.
Sample time for each measurement is calculated by adding (measurement duration)/2 to the sample measurement start time.
Created at: 2012-01-31
Updated at: 2016-11-29
Written by: Vesa Oikonen, Harri Merisaari, Tuula Tolvanen