The Importance of Dosimetry Standardization in Radiobiology

Abstract

Radiation dose is central to much of radiobiological research. Precision and accuracy of dose measurements and reporting of the measurement details should be sufficient to allow the work to be interpreted and repeated and to allow valid comparisons to be made, both in the same laboratory and by other laboratories. Despite this, a careful reading of published manuscripts suggests that measurement and reporting of radiation dosimetry and setup for radiobiology research is frequently inadequate, thus undermining the reliability and reproducibility of the findings. To address these problems and propose a course of action, the National Cancer Institute (NCI), the National Institute of Allergy and Infectious Diseases (NIAID), and the National Institute of Standards and Technology (NIST) brought together representatives of the radiobiology and radiation physics communities in a workshop in September, 2011. The workshop participants arrived at a number of specific recommendations as enumerated in this paper and they expressed the desirability of creating dosimetry standard operating procedures (SOPs) for cell culture and for small and large animal experiments. It was also felt that these SOPs would be most useful if they are made widely available through mechanism(s) such as the web, where they can provide guidance to both radiobiologists and radiation physicists, be cited in publications, and be updated as the field and needs evolve. Other broad areas covered were the need for continuing education through tutorials at national conferences, and for journals to establish standards for reporting dosimetry. This workshop did not address issues of dosimetry for studies involving radiation focused at the sub-cellular level, internally-administered radionuclides, biodosimetry based on biological markers of radiation exposure, or dose reconstruction for epidemiological studies.

Keywords: dosimetry; dosimetry protocols; dosimetry standards; radiobiology; radiobiology protocols; radiobiology standards.

Fig. 1

Accuracy indicates proximity of measurement results to the true (target) value, while precision indicates the repeatability, reproducibility or spread of the measurement.

Fig. 2

An example of a typical dose-response relationship for total-body-irradiated (TBI) non-human primates. The 60-day mortality dose-response relationship is presented as probit percent mortality versus TBI dose (Gy) on a linear scale.

Fig. 3

High dependence of cell survival on dose for different cell types. [Provided by Elizabeth Travis, personal communication.]

Fig. 4

Dose variation in a Cs-137 irradiator shown with a) dose color wash and b) isodose mapping of the +25 % and −15 % variation in dose throughout the irradiation volume [2].

Fig. 5

Energy dependence of thermoluminescent dosimeter (TLD) response [9].

Fig. 6

Variation of dose in water, muscle, bone and fat per unit of air kerma (proportional to exposure) at various energies. [Provided by William Hanson, personal communication.]