Standard Guide for Estimation of Measurement Uncertainty in Dosimetry for Radiation Processing

Importancia y uso:

4.1 Standards such as ISO 11137-1 (radiation sterilization of health care products) and ISO 14470 (irradiation of food) contain requirements that dosimetry used in the development, validation, and routine control of the process shall have measurement traceability to national or international standards and shall have a known level of uncertainty. The magnitude of the measurement uncertainty is important for assessing the results of the measurement system.

4.1.1 This guide provides information on how to meet the fundamental requirement to determine a known level of uncertainty associated with a dose measurement, how to calculate the overall uncertainty, and how the uncertainty may differ depending on the application (e.g., OQ and PQ dose measurements, routine dose measurement, determination of minimum absorbed dose (D_min) or maximum absorbed dose (D_max) from the monitoring location dose (D_mon)). Information is provided on how to identify and calculate different components of uncertainty used to establish an uncertainty budget.

4.2 Information on the range of achievable uncertainty values for specific dosimetry systems is given in the ASTM standards for the specific dosimetry systems. While the uncertainty values given in specific dosimetry standards are achievable, it should be noted that both smaller and larger uncertainty values might be obtained depending on measurement conditions and instrumentation. For more information, see also ASTM 52628.

4.3 This guide uses the methodology adopted by the GUM for estimating uncertainties in measurements (see 2.3). Therefore, components of uncertainty are evaluated as either Type A uncertainty or Type B uncertainty.

4.3.1 Quantifying individual components of uncertainty may assist the user in identifying actions to reduce the combined measurement uncertainty.

4.4 Although this guide provides a framework for assessing uncertainty, it cannot substitute for critical thinking, intellectual honesty, and experience. The evaluation of uncertainty depends on detailed knowledge of the nature of the measurand and of the measurement method and procedure used. The utility of the uncertainty quoted for the result of a measurement therefore ultimately depends on the understanding, critical analysis, and integrity of those who contribute to the assignment of its value (GUM 3.4.8 JCGM 100:2008).

Subcomité:

E61.01

Referida por:

G0213-17R23

Volúmen:

12.02

Número ICS:

17.240 (Radiation measurements)

Palabras clave:

absorbed dose; accuracy; component of uncertainty; dosimeter; dosimetry; e-beam; electron beam; error; gamma radiation; probability density function (pdf); probability distribution; radiation processing; Type A evaluation; Type B evaluation; uncertainty; uncertainty budget; variability; X-radiation; X-ray;