HPS ANSI/HPS N13.32 PDF

Specifications are given in this standard for test categories, test irradiation ranges, and acceptable models with associated levels of performance. A test is conducted when dosimeters are sent from the facility that normally processes or reads the dosimeters (i.e., the “processor”) to a testing organization that facilitates the irradiation of the dosimeters under controlled conditions specified in this standard. The dosimeters are returned to the processor for evaluation. The results of dosimeter processing are returned to the testing laboratory for evaluation under the criteria given in this standard.

The standard applies to dosimetry systems used to assess personal dose equivalent at a depth of 0.07 mm in International Commission on Radiation Units and Measurements (ICRU) tissue in extremities; specifically, hand, elbow, arm below the elbow, foot, knee, leg below the knee. As such, the standard applies to the performance of dosimeters worn on fingers and on wrists or ankles. Because the basis of the performance test is the personal dose equivalent at a depth of 0.07 mm, this standard does not apply to dosimeters used to assess the dose to the lens of the eye or the personal dose equivalent to the whole body. As in the last versions of this standard, no consideration is given to administrative aspects of dosimetry programs such as adequacy of dosimeter identification, detailed formats of reports, field calibrations, placement of dosimeters on extremities, or the assessment of dose from the placement of multiple extremity dosimeters.

The basis of absorbed dose and dose equivalent in this standard is the personal dose equivalent at 0.07 mm specified by both the International Commission of Radiological Protection (ICRP) and the ICRU. Specifically, factors that convert air kerma in photon fields to personal dose equivalent for rod and pillar phantoms are given in ISO 4037-3 [2].

The standard applies to the evaluation of dosimetry performed for radiation protection under low-dose and high-dose level conditions in photon and beta fields. The tests for accident dosimetry are approximately represented by the high-dose category.

As in the earlier standards, N13.32-1995 [1] and N13.32-2008 [3], neutron exposure of the extremities still presents a special problem. The committee reviewed this issue and found no compelling evidence to implement a neutron dose equivalent test for extremity dosimeters at this time. Quoting from the 1995 standard:

“Current neutron fluence-to-dose-equivalent conversion factors specified in recommendations of the NCRP [National Council on Radiation Protection and Measurements] are derived from the maximum value of dose equivalent in a 30- cm diameter cylindrical torso phantom. These values include secondary charged particles from neutron interactions as well as contributions from gamma rays from the absorption of neutrons by hydrogen atoms. The use of data (including the quality factors) from the cylindrical torso phantom model is not applicable for the extremities. Therefore, neutron test categories are not included in this standard. This issue should be reexamined in future revisions of this document or when appropriate fluence-to-dose equivalent conversion factors are established.”

Purpose

This standard establishes standardized testing conditions and criteria to evaluate the performance of personnel extremity dosimetry services.