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G H Kramer

Publications and source records attributed to G H Kramer.

46 records · Page 3Linked to original sources
PubMed1994

The Canadian National Calibration Reference Centre for In-Vivo Monitoring: thyroid monitoring. Part V: Minimizing placement error in a thyroid monitoring system.

This article is the last of a five-part series covering various aspects of occupational thyroid monitoring. This part describes the techniques for minimizing errors due to improper placement of the detector. The impact of counting time and minimum detectable activity as a function of detector position are also discussed. The importance of minimum detectable activity is exemplified by showing how it can be used to ensure that the thyroid monitoring system can detect an amount of radioactivity below the derived investigation level.

Calibration↗
PubMed1994

The Canadian National Calibration Reference Centre for In-Vivo Monitoring. Part II: Sources of errors in thyroid monitoring of occupationally exposed personnel.

This article, the second of a five-part series covering various aspects of occupational thyroid monitoring, addresses the sources of error that can affect the final result obtained from thyroid monitoring, such as geometry effects (thyroid size, thyroid depth, precision and accuracy of the detector placement, and neck-detector distance). The article also suggests ways in which these errors can be minimized and identifies those errors that are difficult to quantify.

Adult↗
PubMed1993

The Canadian National Calibration Reference Centre for In-Vivo Monitoring: thyroid monitoring. Part I: The national inter-comparison programme.

This article is the first part of a five-part series covering various aspects of occupational thyroid monitoring. The Canadian National Calibration Reference Centre for In-Vivo Monitoring conducts a thyroid inter-comparison programme that now includes more than 100 facilities. The scope of the programme, begun in 1988, has greatly expanded in the last two years following a considerable effort to locate and inform facilities. This article presents the details of the programme, its results, and the lessons learned. Subsequent articles will discuss sources of errors, methodology, instrumental configuration, and counting geometry optimization.

Calibration↗
PubMed1992

Evaluation of the Lawrence Livermore National Laboratory (LLNL) torso phantom by bone densitometry and x-ray.

The recent Workshop on Standard Phantoms recommended that the LLNL torso phantom be adopted as a calibration standard for the quantitation of in vivo radioactivity. This phantom was designed for the calibration of systems for the detection of x-rays of less than 20 keV. The anthropomorphic characteristics and tissue substitute composition of the phantom were assessed with techniques using photons of higher energy. Dual photon absorptometry at 42 and 100 keV showed that the phantom was representative of in vivo tissue composition. Chest radiography showed that the phantom was representative of a human even though the stomach, GI tract and the scapulae were not present and air gaps were observed at organ boundaries.

Absorptiometry, Photon↗
PubMed1991

The BRMD BOMAB phantom family.

The Human Monitoring Laboratory (HML) has used the International Commission on Radiological Protection's Report on Reference Man and Canadian anthropomorphic data as guidance to design and construct a family of phantoms corresponding to Reference Man (PM), Reference Woman (PF), Reference Ten-Year-Old (P10), Reference Four-Year-Old (P4), Ninety-five Percentile Man (PM95), and Five Percentile Man (PM5). The PM series also has an accessory chest section (PMacc) to better simulate lung depositions. The phantoms are constructed from high-density polyethylene and fitted with end-recessed filling caps to minimize leakage problems. This paper describes the methodology of construction and presents data so that the phantoms can be reproduced. The phantoms have been used in Canada's National in-vivo Intercomparison Program, and results show that all Canadian in-vivo counting facilities have size-dependent calibrations. Selected data are presented to exemplify this dependence.

Adult↗
PubMed1984

The optimization of the analysis of 63Ni in urine.

A method has been developed that separates 63Ni from urine. The subsequent estimation of activity is by liquid scintillation counting. The urine is wet-ashed by a new procedure which is much faster than conventional ashing methods. Interfering phosphates are removed before a precipitation of Ni as the dimethylglyoxime complex. The effects of the carrier weight, the pH of the phosphate removal step and the pH of the dimethylglyoxime precipitation have been investigated and optimized to give a mean recovery of 97 +/- 8% for 63Ni. The detection limit as defined by Currie (1968) is estimated to be 4.0 pCi (147 mBq) per sample.

Humans↗
PubMedDate not supplied

Assessment of health risks from fallout radiocesium in a hunting and food-gathering society.

Hunting and food-gathering societies are particularly vulnerable to the effects of fallout, since these people are often at the head of natural food chains which can bioaccumulate toxic substances. This paper describes a study on the effects of fallout radiocesium in caribou consumers of northern Canada. Portable whole body counting equipment was transported into five Arctic communities in 1989-90 and used to measure radiocesium body burdens in over 1100 people. The results were compared with a similar survey carried out in 1967-68. The mean body burden for adults in each community had decreased by a factor of 20 to 30 since the earlier survey. It was possible to derive an effective half time of about 4.5 years for the decrease of Cs-137 body burdens in the Arctic. The mean lifetime dose from the ingestion of radiocesium since 1967 amounted to not more than 12 mSv, with possibly an equal contribution from the period before 1967. The current radiation doses are much less than natural background and it is possible to reassure northern residents that caribou meat remains a safe and nutritious food source.

Adolescent↗