1.1 This practice covers the procedures for preparation,
testing and using the acidic aqueous ferrous ammonium sulfate
solution dosimetry system to measure absorbed dose to water
when exposed to ionizing radiation. The system consists of a
dosimeter and appropriate analytical instrumentation. The
system will be referred to as the Fricke dosimetry system. The
Fricke dosimetry system may be used as either a reference
standard dosimetry system or a routine dosimetry system.
1.2 This practice is one of a set of standards that provides
recommendations for properly implementing dosimetry in
radiation processing, and describes a means of achieving
compliance with the requirements of ISO/ASTM Practice
52628 for the Fricke dosimetry system. It is intended to be read
in conjunction with ISO/ASTM Practice 52628.
1.3 The practice describes the spectrophotometric analysis
procedures for the Fricke dosimetry system.
1.4 This practice applies only to gamma radiation,
X-radiation (bremsstrahlung), and high-energy electrons.
1.5 This practice applies provided the following are satisfied:
1.5.1 The absorbed dose range shall be from 20 to 400 Gy
(1).2
1.5.2 The absorbed-dose rate does not exceed 106 Gy·s−1
(2).
1.5.3 For radioisotope gamma sources, the initial photon
energy is greater than 0.6 MeV. For X-radiation
(bremsstrahlung), the initial energy of the electrons used to
produce the photons is equal to or greater than 2 MeV. For
electron beams, the initial electron energy is greater than 8
MeV.
NOTE 1—The lower energy limits given are appropriate for a cylindrical
dosimeter ampoule of 12 mm diameter. Corrections for displacement
effects and dose gradient across the ampoule may be required for electron
beams (3). The Fricke dosimetry system may be used at lower energies by
employing thinner (in the beam direction) dosimeter containers (see ICRU
Report 35).
1.5.4 The irradiation temperature of the dosimeter should be
within the range of 10 to 60°C.
1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appropriate
safety and health practices and determine the applicability
of regulatory limitations prior to use.