Steve A Allen

Publications (3)4.28 Total impact

• Article: Recalibration of the Cameco mobile lung counter.

  Gary H Kramer, Barry Hauck, Steve A Allen
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  ABSTRACT: The Cameco lung counter has been recalibrated using the Lawrence Livermore National Laboratory torso phantom using an extended lung set (i.e., longer than the original set). The previous calibration had used the Japanese Atomic Energy Research Institute torso phantom. The new calibration had lower counting efficiencies and, as a result, higher minimum detectable activities. The recalibrated Cameco lung counter was used to measure an extended lung set that had the volume reduced by using modified planar inserts for the sliced lungs as the extended lung set has a lung volume that is larger than Reference Man. This work has shown that sliced lungs can be used to alter the characteristics of the phantom's lung inserts substantially and provide flexibility in measurements previously not recognized.
  Health physics 07/2009; 96(6):675-81. · 0.92 Impact Factor
• Article: Problems encountered during the calibration of the new Cameco mobile lung counter: detector size or phantom limitation?

  Gary H Kramer, Steve A Allen, Dave Groff
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  ABSTRACT: This paper describes the calibration of the new Cameco mobile lung counter and, more importantly, the problems encountered with recommendations for their long-term solution. The new Cameco lung counting system, which is based on an array of four 80-mm-diameter Canberra BeGe detectors, has used the JAERI phantom for its primary calibration as it more closely resembles ICRP reference data for lung dimensions compared with the LLNL phantom. Although the JAERI phantom's lung dimensions offer advantages over the LLNL phantom's lungs, this phantom is still not ideal. The work described in this paper leads to the conclusion that the LLNL be modified to more closely resemble the ICRP reference data if large area germanium detectors comprise the lung counter. Overlay plate stacking was necessary to achieve the range of chest wall thicknesses found within the Cameco work force (2-8 cm) when using the JAERI phantom. This technique has proved to be robust and is useful for extending the calibration range. Cameco is using group monitoring, which adds spectra to simulate very long counting times (10-20 h), and it is essential that all materials be low background. This was not initially the case here as found from overnight background counts.
  Health Physics 01/2004; 85(6):751-8. · 1.68 Impact Factor
• Source

  Available from: Bernardo Maranhão Dantas

  Article: Lung counting: summing techniques to reduce the MDA.

  Gary H Kramer, Barry M Hauck, Steve A Allen, Bernardo M Dantas, Ana Letícia A Dantas, Adelaide M G F Azeredo
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  ABSTRACT: The new dose limits recently adopted in Canada (and elsewhere in the world) have made it more difficult to detect some radionuclides by in vivo counting at the average dose limit of 20 mSv. This is particularly true for natural uranium. Two techniques have been developed by the Human Monitoring Laboratory to reduce the Minimum Detectable Activity (MDA) for the lung counting of this nuclide. The first technique, developed in collaboration with Cameco, is to either sum sequential counts of an individual or to sum spectra of a group of workers similarly occupationally exposed. This technique offers a reduction in the MDA of up to a factor of three. The second technique, developed in collaboration with CNEN, involves the summing of photopeaks within an individual spectrum and offers a reduction in the MDA of up to a factor of two.
  Health Physics 09/2003; 85(2):220-7. · 1.68 Impact Factor