Methodology for correcting the nonlinear response of radionuclide calibrators

Daniel Da Silva Quaresma,Paulo Gonçalves Da Cunha,Antônio Eduardo De Oliveira,Akira Iwahara

doi:10.15392/bjrs.v9i2.1686

Abstract

Due to constructive and operational issues, the response of a radionuclide calibrator used in Nuclear Medicine can behave in a non-linear manner, especially in the transition of scales. Although the deviations from linearity are small, they may be important for standard secondary or reference radionuclide calibrators used in calibration laboratories. In the document TRS 454 - IAEA it is proposed that the deviation from linearity for these instruments should be in the range of ± 2%. However, calibration laboratories may have some difficulty meeting the requirement. This article proposes an easy-to-implement methodology to correct the response of reference radionuclide calibrators from calibration laboratories, in order to meet the requirement of ± 2% for the linearity parameter recommended by the IAEA.

Highlights

In nuclear medicine, it is important to measure the activity of radiopharmaceuticals before they are injected into patients to certify that the activity is the same as the one prescribed [1]
The values of Mtc (t) obtained by eq 1 are shown in figures 1 and 2 for the CRC-25R and CRC15R radionuclide calibrator, respectively
The results indicate that the nonlinearities of the studied radionuclide calibrator have less impact when compared to the levels of tolerance proposed by the IAEA [5] for Nuclear Medicine Services

Summary

Introduction

It is important to measure the activity of radiopharmaceuticals before they are injected into patients to certify that the activity is the same as the one prescribed [1]. The instruments used to perform these measurements are radionuclide calibrator. The range of activities employed for diagnostic and therapeutic purposes is quite wide, ranging from a few MBq to the order of GBq. The range of activities employed for diagnostic and therapeutic purposes is quite wide, ranging from a few MBq to the order of GBq These activities generate currents in ionization chambers [2] ranging from fA to μA. An electrometer associated with an ionization chamber must be capable of processing eight orders of magnitude of current. It is necessary for the electrometer to adjust its scales automatically. Discontinuities in the responses of the electrometers may occur in the transitions between scales [1]

Methods

Results

Conclusion