Standards Development

Scope

This International Standard specifies the performance requirements of radiotherapy dosimeters (3.111), intended for the measurement of absorbed dose to water (3.4) or air kerma (3.8) (and their rates and spatial distributions) in photon (3.98), electron (3.39), proton or light and heavy ion radiation fields (3.105) as used in radiotherapy (3.110).

Specificly, the document outlines general and specific performance requirements for detector assemblies (3.29) (ionization chambers (3.64) and solid-state detectors (3.136)), measuring assemblies (3.75), and stability check devices (3.141). These requirements cover aspects such as stability, leakage current, radiation quality dependence, and more.

The following devices are outside the scope of this document and therefore not covered here:

–        Dose monitoring systems (3.35) incorporated in radiotherapy (3.110) treatment machines

–        Re-entrant (also known as well-type) ionization chambers (3.64) used for brachytherapy source calibration

–        constancy check devices

This document is applicable to the following types of dosimeter:

a)      Dosimeters, classified as reference-class dosimeters (3.122) , normally used for

1)      kerma (3.67) or dose determination under reference conditions;

2)      the calibration of field-class dosimeters (3.50) ;

NOTE 1 reference-class dosimeters (3.122) may be used as field-class dosimeters (3.50).

b)      Dosimeters, classified as field-class dosimeters (3.50), normally used for

1)      the measurement of kerma (3.67) or dose in a radiation beam (3.104), either in air or in a phantom (3.97);

2)      relative dose distribution measurements with a scanning system (3.130) such as an automatic water phantom (3.97).

NOTE 2 In this document, field-class dosimeters (3.50) and reference-class dosimeters (3.122) employ ionization chambers (3.64) as detector (3.28)

c)      Solid-state dosimeters (3.138), where the solid-state detector (3.136) is intended for operation at zero bias voltage, normally used for

1)      relative dose distribution measurements with a scanning system (3.130) such as an automatic water phantom (3.97);

2)      point-dose measurements in a solid-state phantom (3.97) or automatic water phantom (3.97).

NOTE 3 Solid-State detectors that are intended for In-Vivo dosimetry applications are outside the scope of this document.

The object of this documentis:

–        to establish requirements for a satisfactory level of performance for radiotherapy dosimeters (3.111);

–        to standardize methods for the determination of compliance with this level of performance.

Three levels of performance are specified:

–        a lower level of performance applying to field-class dosimeters (3.50);

–        a higher level of performance applying to reference-class dosimeters (3.122);

–        a specific level of performance applying to dosimeters where at least one detector assembly is a Solid-state detector (3.136). This may also be designated as solid-state class