ANSI HPS N13.11-2009 Personnel Dosimetry Performance - Criteria for Testing.pdf

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1、 American National Standard ANSI/HPS N13.11-2009 (R2015) Personnel Dosimetry Performance Criteria for Testing Approved 13 January 2009 Reaffirmed 12 March 2015 American National Standards Institute, Inc. ii Published by Health Physics Society 1313 Dolley Madison Blvd. Suite 402 McLean, VA 22101 Copy

2、right 2015 by the Health Physics Society. All rights reserved. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior written permission of the publisher. Printed in the United States of America ANSI/HPS N13.11-2009 (R2015) ANSI/HPS N

3、13.11-2009 iii This standard was consensus-balloted and approved by the ANSI-accredited HPS N13 Committee on September 9, 2008. At the time of balloting, the HPS N13 Committee had the following membership: Chairperson Tracy Ikenberry American College of Occupational and Environmental Medicine Bryce

4、Breitenstein American Industrial Hygiene Assoc. Irene Patrek American Iron and Steel Institute Anthony LaMastra American Mining Congress Scott C. Munson American Nuclear Insurers Bob Oliveira American Nuclear Society Nolan E. Hertel Conference of Radiation Control Program Directors Shawn Seeley Coun

5、cil on Ionizing Radiation Msmts dosimeter vendors; government, military, and national standards laboratories; and the nuclear power industry. The group held eight meetings over a period of three years to create this third revision of the original standard. At the first meeting of this working group,

6、 members and experts from outside the group were invited to make presentations about concerns with the 2001 version of the standard. As a result of these presentations and initial discussions, about a dozen major issues were identified that were considered in the writing of this version of the stand

7、ard. The following paragraphs describe how the group resolved many of the issues. Some of these items are treated in detail in the appendices. Historically, N13.11 has been somewhat of a hybrid of a type test and a periodic test. This version can also be generally perceived in that way. Most critici

8、sms of such a hybrid test concern the high cost to test participants. It is suggested that if there were two separate tests (i.e., type and periodic), there would likely be a high “front-end“ cost and a lowering of periodic costs. The working group was sensitive to the cost issue and has helped the

9、situation by reducing the number of test categories from six to five. The group endeavored to reduce the number of dosimeters required for testing while making the test comprehensive enough for the needs of both DOELAP and NVLAP. The six categories in HPS N13.11-2001 have been reduced to five in thi

10、s standard by combining the two photon categories, thereby embedding mixtures within the photon category. The 58 x-ray beam codes approved for use in HPS N13.11-2001 have been reduced to 33 in this standard. To accommodate the increased complexity of the new photon mixtures category, the number of d

11、osimeters used in this category has been raised from 15 to 21. The narrow-spectrum series (i.e., 241Am, 137Cs, and 60Co), particularly appropriate for DOE facilities, remains as an option in the photon category. ANSI/HPS N13.11-2009 viiiThe beta category has been modified to make 85Kr the sole low-e

12、nergy beta-particle source; 204Tl has been eliminated. While functionally similar, the 85Kr half-life is longer, and its available activities are greater than for 204Tl. In addition, testing with uranium in a slab geometry has been added as a special subcategory. The performance criteria have been c

13、hanged to be consistent with ANSI/HPS N13.32-2008. The tolerance equation is now B2+ S2 L2, where B is the bias, S is the standard deviation, and L is the tolerance level. The value of L is 0.24 for the accident photon category and 0.3 for all other categories. After much discussion, the performance

14、 quotient limit (PQL) introduced in the previous version of the standard was eliminated. The group concluded that the revised pass/fail criteria and other changes rendered the tests sufficiently challenging. The dose ranges for the accident and non-accident categories have traditionally had a breakp

15、oint at 100 mSv (10 rem). To prevent excessive numbers of dosimeters from being damaged by such high doses, the upper limit of the range for the photon mixture category has been decreased to 50 mSv (5 rem); the group believed that the number better reflected a reasonable upper limit on routine occup

16、ational doses. The lower limit of the range for the photon mixture category has been changed to 0.5 mSv (50 mrem) because no single photon personal dose equivalent is allowed to be less than 0.25 mSv (25 mrem). Since the regulatory limit for the shallow dose equivalent is a factor of 10 higher than

17、for deep dose equivalent, the upper limit of the beta and photon/beta mixture categories has been increased to 250 mSv (25 rem). Similarly, the lower limit of the beta category has been raised to 2.5 mSv (250 mrem) and the photon/beta mixture category lower limit for shallow dose equivalent has been

18、 raised to 3 mSv (300 mrem). The upper limit of the neutron/photon mixture category remains at 50 mSv (5 rem) for practical irradiation time considerations. The lower limit of 1.5 mSv (150 mrem) remains for the neutron/photon mixture category. Limits have been placed on the number of dosimeters that

19、 can be irradiated in certain dose regions: no more than two dosimeters in a test may be irradiated below twice the lower dose limit, and no more than two may be irradiated above half of the upper dose limit. Because so many dosimeters were being irradiated at non-perpendicular angles under the prev

20、ious version of the standard, limits have been placed on the number of non-perpendicular irradiations in the photon category. Finally, in the beta/photon category, the shallow dose equivalent:deep dose equivalent ratio has been modified such that the ratio of the photon Hp(0.07) to the beta particle

21、 Hp(0.07) is restricted to be in the range of 1:1 to 1:6, inclusive, to better reflect some workplace environments. The conversion coefficients for photons used in this standard are unchanged from the previous version of the standard. However, after much discussion, the working group decided to chan

22、ge the neutron fluence to personal dose equivalent conversion coefficients to those currently promulgated by the International Organization for Standardization (ISO). Because the ISO coefficients were calculated for a slab phantom making use of the latest alpha and proton stopping power information,

23、 such a change results in technical consistency with the coefficients for the other types of radiation used in this standard. For practical purposes, the polymethyl methacrylate (PMMA) phantom will continue to be used in this standard, but with the addition of a specification for phantom backscatter

24、. Also, the reference dose point (RDP) will continue to be on the phantom surface (i.e., the current NVLAP practice). However, the irradiating laboratory (IL) may adjust the absorbed dose or personal dose equivalent at the sensitive elements of the dosimeter, if the test participant desires it and s

25、upplies the distance between the surface of the phantom and the sensitive elements. Finally, the test schedule has been tightened by requiring that the IL return dosimeters to the test participant within 15 calendar days from the completion of each round of testing. In addition, this standard recomm

26、ends that the test participant report results within 15 calendar days from receipt of the dosimeters from the IL. Suggestions for improvement of this standard will be welcome. They should be sent to the Health Physics Society, 1313 Dolley Madison Boulevard, Suite 402, McLean, VA 22101. ANSI/HPS N13.

27、11-2009 1 AMERICAN NATIONAL STANDARD ANSI/HPS N13.11-2009 American National Standard for Dosimetry Personnel Dosimetry Performance Criteria for Testing 1.0 Purpose and Scope 1.1 Purpose This standard establishes the test conditions and performance criteria for evaluating personnel dosimetry systems.

28、 1.2 Scope This standard applies to dosimetry systems used to determine personal dose equivalent for occupational conditions and absorbed dose for accident conditions. Tests are conducted under controlled conditions and include irradiation with photons, beta particles, neutrons, and selected mixture

29、s of these radiations. The range of delivered absorbed doses or personal dose equivalents and tolerance levels are based on considerations of radiation protection expressed in current publications of the National Council on Radiation Protection and Measurements (NCRP 1993), the International Commiss

30、ion on Radiation Units and Measurements (ICRU 1992), and the International Commission on Radiological Protection (ICRP 1991, 1997). Organizations should be tested in those categories that best represent the dosimetry services they provide or use. The tests outlined in this standard may be used to te

31、st the suppliers of dosimetry services (processors). The standard integrates angular testing using photon fields incident at various angles to the plane of the dosimeter. Such tests provide the test participant with: a method to continuously evaluate long-term changes in dosimeter construction, and

32、information for improving absorbed dose or personal dose equivalent estimation under field conditions. Several dosimetry uses and radiological conditions are outside the scope of this standard because of dosimeter design, limitations of dosimetry systems, and practical considerations of testing equi

33、pment and sources. These include: thermal neutrons, high-energy neutrons ( E 3 MeV), and extremity dosimeters (covered in ANSI/HPS N13.32-2008). The scope of this standard is sufficiently comprehensive that satisfactory performance implies that a dosimetry processor or user is competent to assess pe

34、rsonal dose under a broad range of field conditions using the tested dosimetry system for those categories for which they were tested. 2.0 Definitions Absorbed dose, D: The quotient of d by dm, where d is the mean energy imparted by ionizing radiation to matter of mass dm, thus: mDdd=Unit: J kg1Note

35、 1: The special name for the unit of absorbed dose is gray (Gy). The special unit of absorbed dose, rad, is 102Gy. Note 2: The definition of the absorbed dose, D, as a point function, allows the specification of the spatial variations of D as well as the distribution of the absorbed dose in linear e

36、nergy transfer at the point of interest. (Eq. 1) ANSI/HPS N13.11-2009 2 EENEEENEEEEEd)(d)(maxminmaxmin=Note 3: Shallow absorbed dose is defined as the absorbed dose at a depth of 0.07 mm in ICRU tissue and is denoted by D(0.07). Deep absorbed dose is defined as the absorbed dose at a depth of 10 mm

37、in ICRU tissue and is denoted by D(10). Air kerma, Ka: The quotient of dEtrby dm, where dEtris the sum of the initial kinetic energies of all electrons liberated by photons in a volume element of air of mass dm, thus: (Eq. 2) Note: The unit of the air kerma is gray, which has units of joules per kil

38、ogram (J kg1) Average energy, E : The fluence-weighted average energy of a field of photons, beta-particles, or neutrons calculated as: where N(E) is the fluence with energy between E and E + dE, Emaxis the maximum energy present in the spectrum, and Eminis the minimum energy considered for the aver

39、age. Bias, B: The mean value of the performance quotient, Pi, of a set of dosimeter test results: where the sum is extended over all n values of Pifor a particular test in a given radiation category (or subcategory), and for a particular phantom depth (shallow or deep), and where n is the number of

40、test dosimeters included in the test for that category and depth. Calibration: The quantitative determination, under a controlled set of standard test conditions, of the reading given by a dosimeter as a function of the value of the quantity to be measured. Conventional quantity value: The quantity

41、value attributed by agreement to a quantity for a given purpose. Note 1: The conventional quantity value is the best estimate of the value of the quantity to be measured, determined by a primary standard or a transfer standard that is traceable to a primary standard. Within an organization, the resu

42、lt of a measurement obtained with a secondary standard instrument may be taken as the conventional value of the quantity to be measured. Note 2: A conventional quantity value is, in general, regarded as being sufficiently close to the true quantity value for the difference to be insignificant for th

43、e given purpose. Conversion coefficient: The quotient of personal dose equivalent, Hp(d,), by the quantity for which the field is calibrated (“field quantity“), air kerma or fluence, averaged over the field spectrum, thus: where for photons d is 0.07 mm in ICRU tissue for the shallow depth and 10 mm

44、 for the deep depth, and is the angle of radiation incidence. Note 1: The unit of the conversion coefficient is Sv Gy1(rem rad1) for photons and Sv m2(rem m2) for neutrons. Note 2: For the purposes of this standard, photon conversion coefficients for ISO techniques are taken from ICRU (1998) and for

45、 the NIST techniques from Soares and Martin (1995). For neutrons, values for the conversion coefficients are taken from ISO (1998). Note 3: For beta particles, because the field quantity is absorbed dose and the quality factor is unity, the conversion coefficient is unity. Dosimeter: A device to ass

46、ess the absorbed dose or personal dose equivalent from ionizing radiation received by a person. The dosimeter consists of radiation-sensitive elements and their surrounding packaging. =niiPnPB1)/1(ap,),(KdHcdK=np)(10Hc =mEKddtra=(Eq. 4) (Eq. 3) for photons (Eq. 5) for neutrons (Eq. 6) ANSI/HPS N13.1

47、1-2009 3 Equivalent dose, HT,R: The product of DT,Rand wR, where DT,Ris the mean absorbed dose in an organ or tissue and wRis the radiation weighting factor for the radiation incident on the body, thus: HT,R= wRDT,RNote 1: The unit of the equivalent dose is joules per kilogram (J kg1) with the speci

48、al name sievert (Sv). The special unit of equivalent dose, rem, is 102Sv. Note 2: For the purposes of this standard, for photon and beta radiation, the radiation weighting factor has the value unity. Full width at half-maximum, FWHM: The width of a continuum spectrum at half of its maximum value, ne

49、glecting any monoenergetic lines. Half-value layer: The thickness of material that reduces the air kerma of a radiation beam by one half. Homogeneity coefficient: The ratio of the first and second half-value layers times 100. ICRU tissue: A tissue-equivalent (TE) material defined in ICRU Report 33 (ICRU 1980) having a density of 1 g cm3and a composition by mass of 76.2% oxygen, 10.1% hydrogen, 11.1% carbon, and 2.6% nitrogen. Irradiating laboratory, IL: A laboratory possessing radiation sources, calibration e