Publications by authors named "Jeroen W Thompson"

3 Publications

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Deterministic Effects to the Lens of the Eye Following Ionizing Radiation Exposure: is There Evidence to Support a Reduction in Threshold Dose?

Health Phys 2018 03;114(3):328-343

Ionizing radiation exposure to the lens of the eye is a known cause of cataractogenesis. Historically, it was believed that the acute threshold dose for cataract formation was 5 Sv, and annual dose limits to the lens were set at 150 mSv. Recently, however, the International Commission on Radiological Protection has reduced their threshold dose estimate for deterministic effects to 0.5 Gy and is now recommending an occupational limit of 20 mSv per year on average. A number of organizations have questioned whether this new threshold and dose limit are justified based on the limited reliable data concerning radiation-induced cataracts. This review summarizes all of the published human epidemiological data on ionizing radiation exposure to the lens of the eye in order to evaluate the proposed threshold. Data from a variety of exposure cohorts are reviewed, including atomic bomb survivors, Chernobyl liquidators, medical workers, and radiotherapy patients. Overall, there is not conclusive evidence that the threshold dose for cataract formation should be reduced to 0.5 Gy. Many of the studies reviewed here are challenging to incorporate into an overall risk model due to inconsistencies with dosimetry, sample size, and scoring metrics. Additionally, risk levels in the studied cohorts may not relate to occupational scenarios due to differences in dose rate, radiation quality, age at exposure and latency period. New studies should be designed specifically focused on occupational exposures, with reliable dosimetry and grading methods for lens opacities, to determine an appropriate level for dose threshold and exposure limit.
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http://dx.doi.org/10.1097/HP.0000000000000810DOI Listing
March 2018

New radiometric ages for the BH-1 hominin from Balanica (Serbia): implications for understanding the role of the Balkans in Middle Pleistocene human evolution.

PLoS One 2013 6;8(2):e54608. Epub 2013 Feb 6.

School of Geography and Earth Sciences, McMaster University, Hamilton, Ontario, Canada.

Newly obtained ages, based on electron spin resonance combined with uranium series isotopic analysis, and infrared/post-infrared luminescence dating, provide a minimum age that lies between 397 and 525 ka for the hominin mandible BH-1 from Mala Balanica cave, Serbia. This confirms it as the easternmost hominin specimen in Europe dated to the Middle Pleistocene. Inferences drawn from the morphology of the mandible BH-1 place it outside currently observed variation of European Homo heidelbergensis. The lack of derived Neandertal traits in BH-1 and its contemporary specimens in Southeast Europe, such as Kocabaş, Vasogliano and Ceprano, coupled with Middle Pleistocene synapomorphies, suggests different evolutionary forces acting in the east of the continent where isolation did not play such an important role during glaciations.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0054608PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3566111PMC
December 2013

Optically stimulated luminescence dosimetry with gypsum wallboard (drywall).

Radiat Prot Dosimetry 2010 Sep 6;141(1):1-9. Epub 2010 May 6.

Department of Medical Physics and Applied Radiation Sciences, McMaster University, 1280 Main St West, Hamilton, ON, Canada L9H 6L6.

Gypsum wallboard (drywall) represents an attractive target for retrospective dosimetry by optically stimulated luminescence (OSL) in the event of a radiological accident or malicious use of nuclear material. In this study, wallboard is shown to display a radiation-induced luminescence signal (RIS) as well as a natural background signal (NS), which is comparable in intensity to the RIS. Excitation and emission spectra show that maximum luminescence intensity is obtained for stimulation with blue light-emitting diodes (470 nm) and for detection in the ultraviolet region (290-370 nm). It is necessary to decrease the optical stimulation power dramatically in order to adequately separate the RIS from the interfering background signal. The necessary protocols are developed for accurately measuring the absorbed dose as low as 500 mGy and demonstrate that the RIS decays logarithmically with storage time, with complete erasure expected within 1-4 d.
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http://dx.doi.org/10.1093/rpd/ncq143DOI Listing
September 2010