Publications by authors named "H Cullings"

Purpose: Epidemiological studies of stochastic radiation health effects such as cancer, meant to estimate risks of the adverse effects as a function of radiation dose, depend largely on estimates of the radiation doses received by the exposed group under study. Those estimates are based on dosimetry that always has uncertainty, which often can be quite substantial. Studies that do not incorporate statistical methods to correct for dosimetric uncertainty may produce biased estimates of risk and incorrect confidence bounds on those estimates.

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In this article we review the history of key epidemiological studies of populations exposed to ionizing radiation. We highlight historical and recent findings regarding radiation-associated risks for incidence and mortality of cancer and non-cancer outcomes with emphasis on study design and methods of exposure assessment and dose estimation along with brief consideration of sources of bias for a few of the more important studies. We examine the findings from the epidemiological studies of the Japanese atomic bomb survivors, persons exposed to radiation for diagnostic or therapeutic purposes, those exposed to environmental sources including Chornobyl and other reactor accidents, and occupationally exposed cohorts.

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In radiation risk estimation based on the Radiation Effects Research Foundation (RERF) cohort studies, one common analysis is Poisson regression on radiation dose and background and effect modifying variables of an aggregate endpoint such as all solid cancer incidence or all non-cancer mortality. As currently performed, these analyses require selection of a surrogate radiation organ dose, (e.g.

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Article Synopsis
  • The DS02 dosimetry system, used to assess cancer risks among atomic bomb survivors, employs three simplified body models but lacks accurate representation for fetal organ doses, relying instead on the uterine wall of an adult phantom.
  • To improve accuracy, the RERF Working Group has developed the J45 series of high-resolution voxel phantoms that include various body types from newborns to adults, along with four pregnant female models at different gestational ages.
  • Recent comparisons show that organ doses calculated using these new J45 phantoms, especially in realistic postures like kneeling and lying down, reveal that the DS02 system may overestimate doses by up to 1.45 times for certain exposure scenarios.
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Article Synopsis
  • Scientists learned about the effects of radiation on unborn babies by studying women who were pregnant during the atomic bomb explosions in Hiroshima and Nagasaki.
  • They used special models called phantoms to estimate how much radiation the babies inside these women received at different pregnancy stages.
  • The study found that the previous estimates of radiation exposure were too high, especially for the babies' brains later in pregnancy.
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