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.

Specifications

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.

  1. Take the value of coincidents counts on 4th data column
  2. Divide it by measurement duration in seconds (difference of times on column 2 in seconds)
  3. If the background activity was specified in the header lines, subtract it from counts-per-sec value (outcome of the previous step)
  4. 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
  5. Multiply the two calibration coefficients with each other
  6. Divide the calibration coefficient by the branching ratio of the radioactive label isotope (isotope can be identified based on halftime in the headers)
  7. Multiply the count-per-second value from step #3 by the combined calibration coefficient
  8. 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.



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Updated at: 2016-11-29
Created at: 2012-01-31
Written by: Vesa Oikonen, Harri Merisaari, Tuula Tolvanen