Stability of Calibration Factors of Survey Meters: A Five-Year Comparative Study

Document Type : Original Paper

Authors

1 Ghana Atomic Energy Commission, Radiation Protection Institute, health Physics Centre

2 1. Radiation Protection Institute, Ghana Atomic Energy Commission, PO Box LG80, Legon, Accra, Ghana 2. Department of Nuclear Safety and Security, Graduate School of Nuclear and Allied Sciences, University of Ghana, PO Box AE1, Kwabenya, Accra, Ghana

3 Radiation Protection Institute, Ghana Atomic Energy Commission, PO Box LG80, Legon, Accra, Ghana

4 Department of Basic Sciences, School of Basic and Biomedical Sciences, University of Health and Allied Sciences, Private Mail Bag 31, Ho, Ghana

5 Department of Physics, Kwame Nkrumah University of Science and Technology, Private Mail Bag, Kumasi, Ghana

6 Department of Physics, University of Cape Coast, Cape Coast.

7 Department of Nuclear Safety and Security, Graduate School of Nuclear and Allied Sciences, University of Ghana, PO Box AE1, Kwabenya, Accra, Ghana

10.22038/ijmp.2025.78361.2385

Abstract

Introduction: Analysis of historical calibration data can reveal a lot about survey meters. The study aims to analyse a five-year historical calibration data of selected survey meters for the stability of indication or otherwise.
Material and Methods: A 1000-cc Physikalisch-Technische-Werkstaetten (PTW) spherical ionisation chamber coupled to a PTW UNIDOS Electrometer was used as the reference dosimeter to determine ambient dose equivalent in a 137Cs radiation beam. Ten survey meters were calibrated every year by the substitution method for five continuous years. The yearly calibration results were analysed. These survey meters are used in border and port control, extractive mining industry, non-destructive testing industry, and health care delivery.
Results: Analysis revealed that there are deviations in the calibration factors (CFs) from their initial year 2019 values for all devices. The percentage deviations in the CFs in the year 2020 and beyond from year 2019 values ranged from -34% to 24%. Averagely, each device overestimated its indication of ambient dose equivalent by 0.075 ± 0.009 mSv/h within the five years and underestimated the ambient dose equivalent by an average of 0.163 ± 0.019 mSv/h.
Conclusion: The stability of calibration factors of the survey meters degraded with time and usage. Survey meters that are out of calibration produce inaccurate measurements. To help detect the instability early, it is suggested that users of survey meters resort to counting statistics on their measured data at regular intervals.

Keywords

Main Subjects

References

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Iranian Journal of Medical Physics
Volume 22, Issue 3 - Serial Number 3
May and June 2025
Pages 156-164

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History

  • Receive Date: 26 February 2024
  • Revise Date: 24 July 2025
  • Accept Date: 26 July 2025

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