HPS ANSI/HPS N13.32

Specifications are given in this standard for test categories,test irradiation ranges, and acceptable models with associatedlevels of performance. A test is conducted when dosimeters are sentfrom the facility that normally processes or reads the dosimeters(i.e., the “processor”) to a testing organization that facilitatesthe irradiation of the dosimeters under controlled conditionsspecified in this standard. The dosimeters are returned to theprocessor for evaluation. The results of dosimeter processing arereturned to the testing laboratory for evaluation under thecriteria given in this standard.

The standard applies to dosimetry systems used to assesspersonal dose equivalent at a depth of 0.07 mm in ICRU tissue inextremities, specifically, hands or feet and forearms or legs. Assuch, the standard applies to the performance of dosimeters worn onfingers and on wrists or ankles. Because the basis of theperformance test is the personal dose equivalent at a depth of 0.07mm, this standard does not apply to dosimeters used to assess thedose to the lens of the eye or the personal dose equivalent to thewhole body. As in the previous version of this standard, noconsideration is given to administrative aspects of dosimetryprograms such as adequacy of dosimeter identification, detailedformats of reports, field calibrations, placement of dosimeters onextremities, or the assessment of dose from the placement ofmultiple extremity dosimeters.

The basis of absorbed dose and dose equivalent in this standardis the personal dose equivalent at 0.07 mm specified in both theInternational Commission of Radiological Protection (ICRP) and theInternational Commission on Radiation Units and Measurements(ICRU). Specifically, factors that convert air kerma in photonfields to personal dose equivalent for rod and pillar phantoms aregiven in ISO 4037-3 (ISO 1999).

The standard applies to the evaluation of dosimetry performedfor radiation protection under low-dose and high-dose conditions inphoton and beta fields. The tests for accident dosimetry areapproximately represented by the high-dose category.

As in the earlier standard, N13.32-1995 (ANSI/HPS 1995), neutronexposure of the extremities still presents a special problem. Thecommittee reviewed this issue and found no compelling evidence toimplement a neutron dose equivalent test for extremity dosimetersat this time. Quoting from the previous standard:

Current neutron fluence-to-dose-equivalent conversion factorsspecified in recommendations of the NCRP are derived from themaximum value of dose equivalent in a 30-cm diameter cylindricaltorso phantom. These values include secondary charged particlesfrom neutron interactions as well as contributions from gamma raysfrom the absorption of neutrons by hydrogen atoms. The use of data(including the quality factors) from the cylindrical torso phantommodel is not applicable for the extremities. Therefore, neutrontest categories are not included in this standard. This issueshould be reexamined in future revisions of this document or whenappropriate fluence-to-dose equivalent conversion factors areestablished.

A concerted effort has been made in this standard to segregatetype-testing issues, typically performed once in the lifetime of adosimeter system, from periodic performance testing issues. Assuch, there is no specific requirement to conduct a one-timeevaluation of dosimeter performance under conditions ofnonperpendicular angular incidence. Neither is there a requirementto conduct a study to evaluate the lower limit ofdetectability.These tests are important in the interpretation ofdosimeter results but should be addressed in a type-testingstandard.

The methodology and criteria presented in this standard providethe basis for evaluating the performance of extremity dosimetersystems. Section 2 comprises a list of terms and definitions usedin the standard. Section 3 ANSI/HPS N13.32-2008 2 comprises thetesting procedures, testing categories, specifications of testingfields, specification of testing phantoms, specification ofirradiation geometries, selection of irradiation levels, and theassignment of shallow dose equivalent. Section 4 describes thecriteria by which performance is judged to be acceptable.

Following the example set in the standard for testing whole-bodypersonnel dosimeter systems, N13.11-2001 (ANSI/HPS 2001), ancillaryinformation to clarify and support the positions in this standardis included in the appendices.

The scope of this standard is sufficiently comprehensive thatsatisfactory performance implies that a dosimetry processor orprovider is competent to assess personal extremity dose under abroad range of field conditions using the tested dosimetrysystem.

Purpose

This standard establishes standardized testing conditions andcriteria to evaluate the performance of personnel extremitydosimetry services.

Edition:

08

Published:

01/01/2008

ANSI:

ANSI Approved

Number of Pages:

51