RESUMO
OBJECTIVE: The aim of this work is to determine the calibration factor for Sm-153 and evaluate the influence of the geometry in the activity measurements in order to administer accurately the activity to the patient. METHODS: The calibration factor for Sm-153 was determinated using the Sm-153 sources commonly used in clinical practice and the calibrator response in a known calibration setting. The geometry correction factor for the vial and the plastic syringe was calculated using the real activity indicated by the manufacturer and the activity measured in the vial and in the plastic syringe. RESULTS: The calibration factor obtained is 239 +/- 4 and the correction factor which takes in consideration the geometry is 0,87 +/- 0,07. The activity measured in the syringe is eighteen percent higher to activity measured in the vial. CONCLUSION: This method allows to measure accurately the activity of Sm-153 in vial and syringe applying this geometry correction factor to determine accurately the activity administered to the patient.
