European Journal of Nuclear Medicine

, Volume 28, Issue 1, pp 81–89

Characteristics of a new fully programmable blood sampling device for monitoring blood radioactivity during PET

Authors

  • Ronald Boellaard
    • Clinical PET Centre, University Hospital Vrije Universiteit, P.O. Box 7057, 1007 MB, Amsterdam
  • Arthur van Lingen
    • Clinical PET Centre, University Hospital Vrije Universiteit, P.O. Box 7057, 1007 MB, Amsterdam
  • Suzette C.M. van Balen
    • Clinical PET Centre, University Hospital Vrije Universiteit, P.O. Box 7057, 1007 MB, Amsterdam
  • Bas G. Hoving
    • Clinical PET Centre, University Hospital Vrije Universiteit, P.O. Box 7057, 1007 MB, Amsterdam
  • Adriaan A. Lammertsma
    • Clinical PET Centre, University Hospital Vrije Universiteit, P.O. Box 7057, 1007 MB, Amsterdam
Original Article

DOI: 10.1007/s002590000405

Cite this article as:
Boellaard, R., van Lingen, A., van Balen, S. et al. Eur J Nucl Med (2001) 28: 81. doi:10.1007/s002590000405

Abstract.

The first performance tests of a new fully programmable blood sampling device for monitoring blood radioactivity during positron emission tomography (PET) are described. Blood is withdrawn through 1-mm internal diameter tubing using an infusion pump which can be operated at rates varying from 0 to 600 ml/h. Activity in blood is measured by a 6-cm-thick bismuth germanate crystal connected to a photomultiplier tube and multichannel analyser (MCA) which are positioned within 6 cm lead shielding. Positioning of the tubing is an exact and simple procedure. The minimal readout time of the MCA is 1 s. Two independent energy windows can be set. Operation of the pump and MCA is fully controlled by a PC, i.e. sampling time, interval time and pump rate can be varied at any time during the PET scan by user-defined scripts. A number of characteristics of the new system were studied, such as sensitivity, dead time, linearity, effect of background radiation and pump rate as a function of input pressure. In addition, dispersion was measured as a function of pump rate. Finally, first clinical results were compared with manual samples. The sensitivity equalled 0.7 and 0.2 cps/Bq for 511- and 1022-keV 30% energy windows, respectively, and the system dead time was 500 ns. The system remained linear within 2% with activity concentrations up to 2.5 MBq/cc. Short-term reproducibility was better than 3% for a 1-h period. Long-term reproducibility was about 5% (1SD), which was mainly caused by variation in the diameter of the tubing. If the device was positioned in such a way that maximum shielding was directed towards the patient, the effects of background radiation from the patient on the measured activity concentration for clinically relevant conditions was minimal (<3%). Pump rate varied with input pressure, but remained constant for a given pressure. Dispersion constants smaller than 0.14 s–1 were observed for pump rates higher than 300 ml/h, indicating that the system dispersion is small. Clinical data showed an excellent agreement to within 3% (1SD) between the results obtained with the new system and manual samples. With the continuous blood sampler radioactivity in blood can be measured accurately during the entire course of the PET scan. Furthermore, the system is fully programmable allowing adjustment of all parameters during a single PET scan.

Positron emission tomography Arterial blood radioactivity Input function

Copyright information

© Springer-Verlag 2000