Terminology

...   Commonly Used Dosimetry Terms (see ASTM E-170 for a comprehensive list of terms).
Dose 

A quantity of ionizing radiation energy imparted per unit mass of a specified material. #test

Dosimetry

A practice of using dosimeters and dosimetry systems to quantify absorbed-dose from sources of ionizing radiation.

Dosimeter

A device that, when irradiated, exhibits a quantifiable change in some property of the device that can be related to absorbed dose in a given material using appropriate analytical instrumentation and techniques.

Discussion: The term “device” is used in order to describe both large dosimeters such as a calorimeter as well as small dosimeters fabricated from pieces of material such as PMMA chips, alanine films and pellets or radiochromic film pieces. The packaging materials and conditioned environment surrounding the dosimeter comprise a complete dosimeter. Since we cannot measure the actual dose absorbed the irradiated materials and materials interfaces themselves, dosimeter are used as surrogates and must be of a size and composition approximately equivalent to the materials and interfaces they represent.

Dosimetry System

System used for measuring absorbed dose, consisting of (a.) dosimeters, (b.) measurement instruments and their associated reference standards, and (c.) procedures for use of the system.

Reference Dosimetry System

A dosimetry system generally having the highest metrological quality available at a given location or in a given organization, from which measurements made there are derived.

Routine Dosimetry System

A dosimetry system calibrated against a reference standard dosimetry system and used for routine absorbed dose measurements, including dose mapping and process monitoring.A dosimetry system used for day-to-day monitoring and control of an industry irradiation process

Dosimeter System Characterization

A determination of performance characteristics, such as useful dose range, reproducibility and the effects of influence quantities, for a dosimeter/dosimetry system under defined conditions. Discussion: Characterization is carried out in order to determine the practices and procedures necessary to control the influence quantities or factors that effect dosimetry results such that the dosimetry system produces results within a normally expected range of performance.

Calibration (of a dosimetry system )

Set of operations that establish, under specified conditions, the relationship between values of quantities indicated by a measuring instrument or measuring system, or values represented by a material measure or a reference material, and the corresponding values realized by (dose) standards.

Calibration Curve

Mathematical expression of the relation between dosimeter response and corresponding value of dose certified traceable to a national or international standard dose.

Traceability

A property of the result of a measurement or the value of a standard whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparison, all having stated uncertainties. Discussion: The unbroken chain of comparisons is called a ‘traceability chain’. Traceability is a requirement of any measurement management system.

Uncertainty (of dose estimate )

A parameter associated with the result of a calculation (“dose estimate”) that characterizes the spread of values that could reasonably be attributed to the derived quantity (“dose”).

Note: A statement of uncertainty is required in order to provide meaning to a dose measurement. An uncertainty statement defines the quality of a measurement in terms of calculated limits (typically ±4-7% for a routine dosimetry system) within which the “true” value of the estimated dose is expected to be found with a specified level of confidence (typically approximately 95% or =2). Refer to the ISO/ASTM 51705 uncertainties document for guidance.