ANSI HPS N13.41-2011 Criteria for Performing Multiple Dosimetry.pdf

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1、 American National Standard ANSI/HPS N13.41-2011 Criteria for Performing Multiple Dosimetry Approved December 1996 Revised and Approved October 17, 2011 American National Standards Institute, Inc. Published by Health Physics Society 1313 Dolley Madison Blvd. Suite 402 McLean, VA 22101 Copyright 2011

2、 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 N13.41-2011 iii This standard was develo

3、ped under the authority of the Health Physics Society Accredited Standards Committee (ASC) N13, Radiation Protection. The Working Group responsible for this standard had the following members: Carol D. Berger, Chairperson (Integrated Environmental Management, Inc.) Libby Brateman (University of Flor

4、ida, College of Medicine, Department of Radiology) Paul M. Neeson (U. S. Department of Energy) Kathryn H. Pryor (Pacific Northwest National Laboratory) Dennis A. Stevenson (Medical College of Georgia) R. Craig Yoder (Landauer) iv This standard was consensus balloted and approved by the ANSI-accredit

5、ed HPS N13 Committee on 20 June 1996. It was revised and approved on 29 July 2011. At the time of balloting, the Committee had the following membership: Chairperson Tracy A. Ikenberry Vice Chairperson Michelle L. Johnson American Association of Physicians in Medicine (AAPM) Robert A. Phillips Americ

6、an College of Occupational and Environmental Medicine Lynne Fairobent (alt.)* Bryce Breitenstein American Industrial Hygiene Association (AIHA) Ray Johnson American Iron and Steel Institute Anthony La Mastra American Mining Congress Scott C. Munson American Nuclear Insurers Bob Oliveira American Nuc

7、lear Society (ANS) Nolan E. Hertel Conference of Radiation Control Program Directors (CRCPD) Earl Fordham Council on Ionizing Radiation Measurements and Standards (CIRMS) Chris Soares Council on Radionuclides and Radiopharmaceuticals, Inc. (CORAR) Leonard Smith Health Physics Society (HPS) Sandy Per

8、le Institute of Electrical and Electronic Engineers (IEEE) Greg Komp (alt.) Mike Unterweger Institute of Nuclear Materials Management Vacant National Council on Radiation Protection and Measurements (NCRP) David Schauer National Registry of Radiation Protection Technologists (NRRPT) Dwaine Brown Nuc

9、lear Energy Institute (NEI) Ralph L. Andersen US Department of Commerce Thomas J. McGiff US Department of Energy Thomas OBrien (alt.) Joel Rabovsky US Department of Defense Peter OConnell (alt.) Timothy Mikulski US Department of Homeland Security John Cuellar (alt.) Don Potter US Environmental Prote

10、ction Agency Mike Boyd US Nuclear Regulatory Commission Donald A. Cool US Navy Luis A. Benevides Individual members Joseph P. Ring L. Max Scott Toshihide Ushino A. N. Tschaeche *Alternate v Contents Forward vi 1.0 Introduction . 1 2.0 Scope . 1 3.0 Definitions of Terms . 2 4.0 Criteria for When to U

11、se Multiple Dosimeters 4 5.0 Implementing Multiple Dosimeter Program Requirements . 5 5.1 Dosimeter Type . 6 5.2 Dosimeter Placement . 6 5.3 Number of Dosimeters Needed 6 5.4 Calibration Considerations for Multiple Dosimeters . 7 5.5 Alternatives to the Use of Multiple Dosimetry. 7 5.6 Program Evalu

12、ation . 7 6.0 Effective Dose Determination from Multiple Dosimetry 8 6.1 Compartment Factors for Effective Dose Assignment . 8 6.2 Methodology for Effective Dose Assignment . 8 7.0 Uncertainties in Results . 10 8.0 Records . 10 9.0 References 10 Annex A: Derivation of Compartment Factors . 12 vi For

13、eword (This foreword is not part of American National Standard ANSI/HPS N13.41-2011.) Normal practice for monitoring personnel for exposure to radiation originating outside of the body is to locate a single dosimeter at a location that gives a reasonably accurate but conservative estimate of the dos

14、e received. To do so, the dosimeter is placed at the location of maximum exposure. However, this practice can greatly overestimate the effective dose to the individual. Therefore, the use of more than one dosimeter should be considered in order to arrive at a more realistic effective dose. Whereas i

15、t may be necessary to use multiple dosimeters throughout an individuals monitoring period, a more likely practice may be to use multiple dosimeters for specific operations or activities. The results obtained are then added to the personal dose equivalent measured during the remainder of the monitori

16、ng period with the single dosimeter for determination of compliance. This standard provides criteria for when and how to use multiple dosimeters under conditions incident to routine activities in the presence of ionizing radiation. It also contains the recommended methodology for determining the eff

17、ective dose from external sources when the use of multiple dosimeters has been deemed necessary by radiation protection professionals. In 2007, the International Commission on Radiological Protection (ICRP) released Publication 103, “2007 Recommendations of the ICRP.” The concepts regarding effectiv

18、e dose contained in ICRP Publication 103 form the basis for the recommendations in this standard. However, provisions for application under ICRP Publications 60 and 26 guidance are included as well. Suggestions for improvement of this standard are welcome. Suggestions should be sent to the Health Ph

19、ysics Society, 1313 Dolley Madison Boulevard, Suite 402, McLean, VA 22102. AMERICAN NATIONAL STANDARD ANSI/HPS N13.41-2011 1 Criteria for Performing Multiple Dosimetry 1.0 Introduction For uniform external exposures of the whole body, the International Commission on Radiological Protection (ICRP) ac

20、knowl-edges the use of personal dose equivalent as determined by means of dosimeters worn on the torso of the body as an acceptable means of determining the effective dose from external radiation sources. However, radiation fields may vary spatially as a result of job- or location-specific condition

21、s. Conditions that may contribute to this variability include source geometry (e.g., point sources, line sources, plane sources, or non-uniform deposition patterns), source-to-worker distance and general orientation of the worker with respect to the source, and the presence of equipment or other bar

22、riers that may provide non-uniform radiation shielding of the worker. Other pertinent factors are the energy and/or composition of the radiation field and changes in these as a result of interactions of radiation with matter in the working environment. Data from radiation surveys are essential for a

23、ssessing how these factors affect radiation field variability with respect to a worker and for determining the need for more than one dosimeter. The following are just a few ex-amples of conditions that may indicate such a need: 1. Work in close proximity to point or line sources of radiation that p

24、resents greater exposure potential for the hands and varying exposure potential over the torso; 2. Maintenance work at facilities where variation in source geometry or partial local shielding exist as a result of structures, equipment, and other barriers; 3. Operations performed in the vicinity of r

25、adiation shielding leaks (e.g., pin-holes, cracks), or work involving the use of partial (shadow) shields; 4. Work on reactor, accelerator, and laboratory components, or handling of radioactive waste when the materials in question contain radioactivity that is not uniformly distributed; or 5. Work w

26、hile using protective clothing or leaded garments that may result in non-uniform exposures between pro-tected and unprotected parts of the body. “Multiple dosimetry” is the practice of placing more than one dosimeter on an individuals body to determine the doses at various regions of the torso, head

27、, arms, and legs. This practice may be implemented for a number of reasons, including demonstration of compliance with federal and state regu-lations or administrative requirements, iden-tification of the location of highest exposure, evaluating the effectiveness of radiation control measures before

28、 and after a par-ticular activity, other circumstances when a single measurement may not provide sufficient information for dose control purposes, or to estimate the effective dose from external sources. Multiple dosimeters may be used to monitor different areas of the body when variations in the ra

29、diation field result in significant variations in personal dose equivalent over the body. The significance of exposure to a variable radiation field is dependent upon the exposure to each organ (e.g., blood-forming organs, lens of the eye) and the applicable regulatory dose limits. The criteria pres

30、ented in this standard provide guidance on when to monitor with multiple dosimeters and where to place such dosimeters when their use is deemed necessary, and the interpretation and recording of results after the dosimeters are processed or evaluated. 2.0 Scope The final decision on whether to use m

31、ultiple dosimeters for external dosimetry purposes instead of a strategically placed single dosimeter is left to the judgment of radiation ANSI/HPS N13.41-2011 2 protection professionals. Once multiple dosimeter use has been deemed appro-priate, this standard contains criteria applicable to routine

32、occupational activities on when and how to use them to monitor the body and extremities of individuals exposed to external sources of ionizing radiation. Such conditions may be encountered at medical, research, commercial, weapons disposition, fuel processing, power reactors and other sites. In addi

33、tion, recommen-dations for selecting dosimeter types, placement of dosimeters on the body, interpretation of multiple dosimeter results, and recording of dose information are presented. A program that is compliant with this standard shall include the requirements of the standard, but not necessarily

34、 its recommendations. This standard does not address the cases of internal deposition of radioactive materials, external contamination of the body, or working conditions that do not permit job pre-planning. Sudden or unexpected chan-ges in the radiation environment as might occur during accidents ar

35、e also beyond the scope of this standard. Fetal monitoring is not addressed because it represents a special case not necessarily related to non-uniform irradiation. (Fetal monitoring is for the purpose of estimating the dose to a separate entity, the fetus, and demonstrating an appropriate rate of e

36、quivalent dose accumulation for the period of gestation. Since it is not an example of multiple dosimetry, it is not addressed herein.1) Skin exposures where the area of irradiation is less than 10 cm2(e.g., from a hot particle) are not addressed.2Finally, the recom-mendations of this standard do no

37、t super-cede specific regulations or license requirements. This standard assumes that dosimeter assemblies worn for multiple dosimetry 1The dose to the fetus from external sources is often assessed by mounting a dosimeter on the abdomen of the pregnant worker. 2The National Council on Radiation Prot

38、ection and Measurements, in NCRP Report No. 106, Limit for Exposure to “Hot Particles” on the Skin, provides guidance on assessing the radiation exposure of small skin areas (NCRP 1999). purposes are calibrated and processed to provide an estimate of equivalent dose. Specific guidance on dosimeter p

39、rocessing methodologies, calibrations, and perfor-mance criteria are included only by ref-erence. 3.0 Definitions of Terms In this standard, definitions given by the American Nuclear Society (1986), the International Commission on Radiation Units and Measurements (1980, 1993), the Inter-national Com

40、mission on Radiological Protection (1984, 1991, 2007), and the National Council on Radiation Protection and Measurements (1985) apply, sup-plemented by those given below.3Absorbed Dose: Mean energy imparted to matter by ionizing radiation per unit mass of irradiated material at the place of interest

41、 in that material. The unit of absorbed dose is the gray (Gy) or rad. One rad is equal to 0.01 Gy. Compartments: Areas of the body that are of dosimetric importance for purposes of multiple dosimetry and for which the dose is assumed to be generally uniform. Compartment Factors (WC): Factors used to

42、 weight the results from dosimeters placed over various compartments in order to relate the fractional risk to the organs in the compartment to the total risk from uniform irradiation of the whole body. Dosimeter: A wearable package of absor-bers and radiation-sensitive elements used to estimate per

43、sonal dose equivalent received by an individual over a specific time period. Dosimetry System: A system used to as-sess personal dose equivalent from external radiation. This system includes the selec-tion, placement, and processing of the 3Throughout this standard, the terms “dose” and “effective d

44、ose” may be used interchangeably. For the sake of clarity, several examples have made use of conventional units, such as the “rem.” ANSI/HPS N13.41-2011 3 dosimeters; interpretation and recording of results; and the means by which the quality of results is ensured. Effective Dose (E): The tissue-wei

45、ghted sum of equivalent doses in all specified tissues and organs of the body. It is the sum of the products of the equivalent dose in an organ or tissue (HT) and the tissue weighting factor (wT). Or: Hw= ETT Equivalent Dose (HT): The dose in a tissue or organ, T, given by: RTRTDw = H,where DT,Ris t

46、he mean absorbed dose from radiation, R, in a tissue or organ, and wRis the radiation weighting factor. The unit of equivalent dose is the sievert (Sv) or the rem. One rem is equal to 0.01 Sv. Extremity: The hand, the arm below the elbow, the leg below the knee, or the foot. The extremity compartmen

47、t thus includes the left hand, the right hand, the left arm below the elbow, the right arm below the elbow, the left leg below the knee, the right leg below the knee, the left foot and the right foot. Lens of the Eye: A tissue of concern from a dosimetric and regulatory point of view because of the

48、potential for radiation-in-duced cataracts. The lens of the eye is located at a depth of 300 mg cm2. The lens of the eye constitutes a separate compart-ment. Limiting Value: A user-defined dose quantity of interest for which limits have been established to control radiation exposures. Examples of li

49、miting values may include regulatory limits, ALARA (As Low As Reasonably Achievable) goals, admini-strative limits, Planned Special Exposure limits, or others. Multiple Dosimetry: The practice of using more than one dosimeter to monitor different areas of the body when variations in the radiation field result in significant variations in personal dose equivalent. (Also known as “multiple badge dosimetry” or “multibadg-ing.”) Personal Dose Equivalent (Hp(d): The dose equivalent in soft tissue at an appropriate depth, d, below a specified point