1.1.1 This standard applies to ionization chambers, and instruments using ionization chambers, which are intended for the measurement of exposure, exposure r?te or related quantities in electromagnetic radiation as used in radiotherapy having characteristics within these limits:
— photon energies corresponding to X-radiation generated at voltages between 10 kV and 3 MV and energies of gamma-radiation between 5 keV and 3 MeV;
— exposure r?tes from approximately 3 uA/kg (10~2 R/s) to 30 mA/kg (102 R/s);
— exposures from approximately 0.3 mC/kg (1 R) to 3 C/kg (104 R).
1.1.2 Instruments to which this standard applies are for example:
— REFERENCE INSTRUMENTS intended for the calibration of FIELD INSTRUMENTS;
— FIELD INSTRUMENTS intended for skin surface or intracavitary measurements of exposure on patients;
— FIELD INSTRUMENTS intended for the measurement of exposure in a radiation beam either in air or in a phantom.
1.1.3 A complete exposure meter or exposure-rate meter contains the following components:
— one or more IONIZATION CHAMBER ASSEMBLIES;
— a MEASURING ASSEMBLY (including possibly a separate display device); and may include one or more STABlLi ty CHECK DEVICES.
1.1.4 At the time of writing this standard, dosimeters for use in radiotherapy are customarily cali-brated in terms of the quantities exposure or exposure r?te. Any future change to a related quantity will not invalidate this standard.