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ANSI/HPS N13.32

2008 Edition, January 1, 2008

Complete Document

Performance Testing of Extremity Dosimeters



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Product Details:

  • Revision: 2008 Edition, January 1, 2008
  • Published Date: January 2008
  • Status: Active, Most Current
  • Document Language: English
  • Published By: Health Physics Society (HPS)
  • Page Count: 51
  • ANSI Approved: Yes
  • DoD Adopted: No

Description / Abstract:

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 ICRU tissue in extremities, specifically, hands or feet and forearms or legs. 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 previous version 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 in both the International Commission of Radiological Protection (ICRP) and the International Commission on Radiation Units and Measurements (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 (ISO 1999).

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

As in the earlier standard, N13.32-1995 (ANSI/HPS 1995), 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 previous standard:

Current neutron fluence-to-dose-equivalent conversion factors specified in recommendations of the NCRP 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.

A concerted effort has been made in this standard to segregate type-testing issues, typically performed once in the lifetime of a dosimeter system, from periodic performance testing issues. As such, there is no specific requirement to conduct a one-time evaluation of dosimeter performance under conditions of nonperpendicular angular incidence. Neither is there a requirement to conduct a study to evaluate the lower limit of detectability.These tests are important in the interpretation of dosimeter results but should be addressed in a type-testing standard.

The methodology and criteria presented in this standard provide the basis for evaluating the performance of extremity dosimeter systems. Section 2 comprises a list of terms and definitions used in the standard. Section 3 ANSI/HPS N13.32-2008 2 comprises the testing procedures, testing categories, specifications of testing fields, specification of testing phantoms, specification of irradiation geometries, selection of irradiation levels, and the assignment of shallow dose equivalent. Section 4 describes the criteria by which performance is judged to be acceptable.

Following the example set in the standard for testing whole-body personnel dosimeter systems, N13.11-2001 (ANSI/HPS 2001), ancillary information to clarify and support the positions in this standard is included in the appendices.

The scope of this standard is sufficiently comprehensive that satisfactory performance implies that a dosimetry processor or provider is competent to assess personal extremity dose under a broad range of field conditions using the tested dosimetry system.

Purpose

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