Standard Guide for Performance Qualification (PQ) Dose Mapping in Gamma Irradiation Processing Facilities

Importancia y uso:

4.1 This guide is one of a set of guides and practices that provide recommendations for properly implementing dosimetry when performing PQ dose maps using gamma radiation.

4.1.1 To understand and effectively use this guide, read Practice 52628, which describes the basic requirements that apply when making absorbed dose measurements in accordance with the ASTM International Committee E61 series of dosimetry standards. In addition, Practice 52628 provides guidance on the selection of dosimetry systems and directs the user to other standards that provide information on individual dosimetry systems, calibration methods, uncertainty estimation, and radiation processing applications.

4.2 Radiation processing is carried out under fixed path conditions where: (1) a process load is automatically moved through the radiation field by mechanical means, or (2) a process load is irradiated statically by manually placing product at predetermined positions before the process is started. In both cases, the process is controlled in such a manner that the process load position(s) and orientation(s) are reproducible within specified limits.

Note 2: Static irradiation encompasses irradiation using either manual rotation, no rotation, or automated rotation of the process load.

4.3 Some radiation processing facilities that use a fixed conveyor path for routine processing can also characterize a region within the radiation field for static radiation processing, sometimes referred to as “off-carrier” processing.

4.4 Many radiation processing applications require a minimum absorbed dose (to achieve a desired effect or to fulfill a legal requirement) and a maximum absorbed dose (to ensure that the product, material, or substance still meets functional specifications or to fulfill a legal requirement).

4.5 PQ dose mapping is used to determine the magnitudes and locations of the minimum and maximum doses and their relationships to the absorbed doses at monitoring locations.

4.6 Information from the dose mapping is used to:

4.6.1 Characterize the irradiation process and assess its reproducibility;

4.6.2 Determine the spatial distribution of absorbed doses and the zone(s) of maximum and minimum absorbed doses throughout a process load, which can consist of an actual or simulated product;

4.6.3 Establish the relationship between the dose at a routine monitoring position(s) and the dose within the minimum and maximum dose zones established for a process load (see Practice 51261); and

4.6.4 Provide validation for mathematical dose calculation methods (see Guide E2232):

4.6.4.1 A validated mathematical model can provide information on dose distribution in devices, including in locations where there are large dose gradients, or it is difficult or impossible to place a dosimeter. This information can contribute to the assessment of dose distribution in a device and irradiated process load following the PQ dose mapping.

4.7 ISO 11137 Part 1 forms the fundamental requirements for health care product sterilization, but it does not stipulate the minimum number of PQ dose mapping (DM) irradiation containers. ISO 11137 Part 3 and Guide 52303, both guidance documents, provide clear guidance regarding a minimum number of PQ DM irradiation containers.

4.7.1 Within Part 1, the definition of dose mapping includes the determination of “dose distribution and variability in material.” Similarly, Part 1 states that, “Dose mapping shall be carried out on a sufficient number of irradiation containers to allow determination of the distribution and variability of dose between irradiation containers.” While the use of one PQ dose map irradiation container will determine dose distribution, it will not determine dose variability.

Subcomité:

E61.03

Volúmen:

12.02

Palabras clave:

absorbed dose; dose distribution; dose mapping; dose zone; dosimetry; gamma radiation; irradiator characterization; maximum dose; minimum dose; operational qualification; performance qualification; photons; radiation processing; routine process monitoring; sterilization; uncertainty;