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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #342368
Title: Longitudinal monitoring of whole body counter NaI(TI) detector efficiency

Author
item SHYPAILO, ROMAN - Children'S Nutrition Research Center (CNRC)

Submitted to: Applied Radiation And Isotopes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/4/2017
Publication Date: 4/5/2017
Citation: Shypailo, R.J. 2017. Longitudinal monitoring of whole body counter NaI(TI) detector efficiency. Applied Radiation And Isotopes. 125:74-79.

Interpretive Summary: Whole body gamma counters (WBC) are used in body composition research for measuring total body potassium (TBK). TBK represents the metabolically active portion of fat-free mass. The WBC in our Center uses a large number (54) of NaI(Tl) detectors. It seems to be well accepted that detectors such as ours can degrade with age, and can lose counting efficiency. Yet insights into the magnitude of such changes are hard to find. We examined the long-term performance of our WBC. We updated calibration factors for each of our 54 detectors annually over several years. We looked at how these factors changed from year to year, and compared them to baseline levels. The data show that the WBC measurement efficiency has declined (-1.9%) over the past three years. The rate of the decline seems to be increasing. Tracking the detector calibration factors annually allows us to correct for this decline. More detailed system monitoring helps us maintain system integrity and accuracy. Having more specific performance data on individual components can make system maintenance and repair more straightforward and efficient.

Technical Abstract: Assessing accuracy of radiation counting systems over time is critical. We examined long-term WBC performance in detail. Efficiency factors for 54 detectors were updated annually over several years. Newer efficiency values were compared with baseline and with annual values. Overall system efficiency has declined (-1.9% over 3 yrs) and appears to be doing so at an increasing rate. Having more specific performance data on individual components can make the process of system maintenance and repair more straightforward and efficient.