ASTM D7282-21e1

Standard Practice for Setup, Calibration, and Quality Control of Instruments Used for Radioactivity Measurements

SIGNIFICANCE AND USE
5.1 This practice is consistent with a performance-based approach wherein the frequency of recalibration and instrument testing is linked to the results from continuing instrument quality control. Under the premise of this practice, a laboratory demonstrates that its instrument performance is acceptable for analyzing sample test sources.  
5.2 When a laboratory demonstrates acceptable performance based on continuing instrument quality control data (that is, control charts and tolerance charts), batch QC samples (that is, blanks, laboratory control samples, replicates, matrix spikes, and other batch QC samples as may be applicable) and independent reference materials, traditional schedule-driven instrument recalibration is permissible but unnecessary.  
5.3 When continuing instrument QC, batch QC, or independent reference material sample results indicate that instrument response has exceeded established control or tolerance limits, instrument calibration is required. Other actions related to sample analyses on the affected instruments may be required by the laboratory QM.  
5.4 The data obtained while following this practice will likely be stored electronically. The data remain in electronic storage, where they are readily available to produce plots, graphs, spreadsheets, and other types of displays and reports. The laboratory QM should specify the frequency and performance of data storage backup.
SCOPE
1.1 This practice covers consensus criteria for the setup, calibration, and quality control of nuclear instruments. Setup establishes the operating parameters of the instrument—for example, voltage or discriminator settings. Calibrations determine the instrument’s response characteristics—for example, its counting efficiency or gain. Quality control ensures that the performance of the instrument remains acceptable for its intended use and consistent with the performance at the time of calibration.  
1.2 This practice addresses four of the most commonly used types of nuclear counting instruments: alpha-particle spectrometer, gamma-ray spectrometer, gas proportional counter, and liquid scintillation counter.  
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions that are provided for information only and are not considered standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 14-May-2021
• ICS: 17.240 - Radiation measurements
• Technical Committee: D19 - Water
• Drafting Committee: D19.04 - Methods of Radiochemical Analysis

Relations

• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM D7902-20 - Standard Terminology for Radiochemical Analyses
• Effective Date: 01-May-2020
• Refers: ASTM E2586-19e1 - Standard Practice for Calculating and Using Basic Statistics
• Effective Date: 01-Apr-2019
• Refers: ASTM D7902-18 - Standard Terminology for Radiochemical Analyses
• Effective Date: 01-Feb-2018
• Refers: ASTM D7283-17 - Standard Test Method for Alpha and Beta Activity in Water By Liquid Scintillation Counting
• Effective Date: 01-Jun-2017
• Refers: ASTM D7902-16 - Standard Terminology for Radiochemical Analyses
• Effective Date: 01-Feb-2016
• Refers: ASTM E2586-14 - Standard Practice for Calculating and Using Basic Statistics
• Effective Date: 01-Jun-2014
• Refers: ASTM D7902-14e1 - Standard Terminology for Radiochemical Analyses
• Effective Date: 15-Jan-2014
• Refers: ASTM D7902-14 - Standard Terminology for Radiochemical Analyses
• Effective Date: 15-Jan-2014
• Refers: ASTM E2586-13 - Standard Practice for Calculating and Using Basic Statistics
• Effective Date: 01-Oct-2013
• Refers: ASTM D7283-13 - Standard Test Method for Alpha and Beta Activity in Water By Liquid Scintillation Counting
• Effective Date: 01-Feb-2013
• Refers: ASTM E2586-12b - Standard Practice for Calculating and Using Basic Statistics
• Effective Date: 01-Oct-2012
• Refers: ASTM E2586-12a - Standard Practice for Calculating and Using Basic Statistics
• Effective Date: 15-Feb-2012
• Refers: ASTM E2586-12 - Standard Practice for Calculating and Using Basic Statistics
• Effective Date: 01-Jan-2012
• Refers: ASTM D3648-04(2011) - Standard Practices for the Measurement of Radioactivity
• Effective Date: 01-Jan-2011

Overview

ASTM D7282-21e1 is an international standard developed by ASTM for laboratories performing measurements of radioactivity using nuclear instruments. This practice provides comprehensive criteria for the setup, calibration, and ongoing quality control of nuclear counting devices, including alpha-particle spectrometers, gamma-ray spectrometers, gas proportional counters, and liquid scintillation counters. This performance-based approach is designed to ensure that instrument calibration and testing schedules are linked directly to quality control data, enhancing analytical reliability while also optimizing operational efficiency.

By following this standard, laboratories can consistently demonstrate that their radioactivity measurement instruments remain accurate and reliable for their intended analytical applications. The procedures help ensure that data generated for regulatory compliance, environmental monitoring, or scientific research meet international quality expectations and traceability requirements.

Key Topics

• Instrument Setup: Guidelines for configuring nuclear counters to establish operational parameters (e.g., voltage, discriminator settings) based on manufacturer instructions and laboratory protocols.
• Calibration: Procedures for determining instrument-specific response characteristics, such as counting efficiency or gain, using sources that are traceable to the International System of Units (SI).
• Quality Control: Ongoing QC programs using control charts, tolerance charts, and batch QC measurements to monitor instrument performance and ensure consistency with original calibration.
• Performance-Based Recalibration: The frequency and necessity of recalibration are determined by ongoing QC and test results, enabling laboratories to reduce unnecessary recalibration intervals while maintaining data integrity.
• Electronic Record-Keeping: Emphasis on electronic data management for calibration records, QC results, and backups, supporting efficient data retrieval, reporting, and auditing.

Applications

ASTM D7282-21e1 is widely applicable in any laboratory or testing facility where accurate radioactivity measurement is required. Practical uses include:

• Environmental Monitoring: Ensuring reliable measurements of radionuclides in air, water, soil, and sediment for regulatory compliance and public health safety.
• Drinking Water Analysis: Supporting regulatory testing of alpha and beta activity in water by maintaining instrument accuracy and documented traceability.
• Industrial Quality Assurance: Verifying radioactive contamination or content in products, components, or waste streams.
• Academic and Research Laboratories: Providing robust frameworks for instrument calibration and quality assurance in radioanalytical studies or nuclear research.
• Medical and Radiopharmaceutical Testing: Supporting measurements of radioisotopes in diagnostic or therapeutic products.
• Nuclear Power and Fuel Cycle Operations: Assuring process control, safety, and environmental impacts through validated radioactivity measurements.

By implementing this standard, organizations can reduce risk, improve measurement reliability, and fulfill the quality and documentation expectations of regulatory bodies and accreditation agencies.

Related Standards

Laboratories using ASTM D7282-21e1 can benefit from familiarity with the following related standards for broader quality management and measurement assurance:

• ISO/IEC 17025 - General requirements for the competence of testing and calibration laboratories.
• ANSI N42.22 - Traceability of radioactive sources to the National Institute of Standards and Technology (NIST).
• ANSI N42.23 - Measurement and associated instrumentation quality assurance for radioassay laboratories.
• ANSI/HPS N13.30 - Performance criteria for radiobioassay.
• ASTM D3648 - Practices for the measurement of radioactivity.
• ASTM D7283 - Test methods for alpha and beta activity in water by liquid scintillation counting.
• JCGM 100:2008 - Guide to the expression of uncertainty in measurement.

Integrating ASTM D7282-21e1 with these standards enhances laboratory compliance, improves traceability, and supports the production of globally accepted, high-quality analytical data in the field of radioactivity measurements.

Keywords: radioactivity measurement, instrument calibration, nuclear counting quality control, ASTM D7282, alpha spectrometer, gamma spectrometer, liquid scintillation counter, ISO 17025, electronic records, instrument setup.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
´1
Designation: D7282 − 21
Standard Practice for
Setup, Calibration, and Quality Control of Instruments Used
for Radioactivity Measurements
This standard is issued under the fixed designation D7282; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Editorially corrected Fig. X1.1, Fig. X3.1, and Fig. X4.1 in December 2022.
1. Scope 2. Referenced Documents
1.1 This practice covers consensus criteria for the setup, 2.1 ASTM Standards:
calibration, and quality control of nuclear instruments. Setup D1129Terminology Relating to Water
establishes the operating parameters of the instrument—for D3648Practices for the Measurement of Radioactivity
example, voltage or discriminator settings. Calibrations deter- D7283TestMethodforAlphaandBetaActivityinWaterBy
mine the instrument’s response characteristics—for example, Liquid Scintillation Counting
its counting efficiency or gain. Quality control ensures that the D7902Terminology for Radiochemical Analyses
performance of the instrument remains acceptable for its E2586Practice for Calculating and Using Basic Statistics
intendeduseandconsistentwiththeperformanceatthetimeof
2.2 Other Standards:
calibration.
ANSI N42.22Traceability of Radioactive Sources to the
National Institute of Standards and Technology (NIST)
1.2 Thispracticeaddressesfourofthemostcommonlyused
and Associated Instrument Quality Control
types of nuclear counting instruments: alpha-particle
ANSI N42.23Measurement andAssociated Instrumentation
spectrometer, gamma-ray spectrometer, gas proportional
Quality Assurance for Radioassay Laboratories
counter, and liquid scintillation counter.
ANSI/HPS N13.30Performance Criteria for Radiobioassay
1.3 The values stated in SI units are to be regarded as
ISO/IEC 17025General Requirements for the Competence
standard. The values given in parentheses are mathematical
of Testing and Calibration Laboratories
conversions that are provided for information only and are not
JCGM 100:2008Evaluation of Measurement Data – Guide
considered standard.
to the Expression of Uncertainty in Measurement
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 Definitions:
priate safety, health, and environmental practices and deter-
3.1.1 For definitions of terms used in this standard, refer to
mine the applicability of regulatory limitations prior to use.
Terminologies D1129 and D7902 and Practice E2586.
1.5 This international standard was developed in accor-
3.2 Definitions of Terms Specific to This Standard:
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
mendations issued by the World Trade Organization Technical
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Barriers to Trade (TBT) Committee. Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
This practice is under the jurisdiction ofASTM Committee D19 on Water and 4th Floor, New York, NY 10036, http://www.ansi.org.
is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemical Available from International Organization for Standardization (ISO), 1 rue de
Analysis. Varembé, Case postale 56, CH-1211, Geneva 20, Switzerland, http://www.iso.ch.
Current edition approved May 15, 2021. Published December 2021. Originally Available from Bureau International des Poids et Mesures (BIPM), Pavillon de
approved in 2006. Last previous edition approved in 2014 as D7282–14. DOI: Breteuil F-92312 Sèvres Cedex France, http://www.bipm.org/en/publications/
10.1520/D7282-21E01. guides/gum.html.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D7282 − 21
3.2.1 acceptable verification ratio (AVR), n—ratio of the 3.2.14 measurement quality objective (MQO),
absolute difference between the measured value of the verifi- n—quantitative or qualitative statement of a performance
cation sample and the known value added to the verification objective or requirement for a particular method performance
sample to the square root of the sum of the squares of their characteristic (1).
associated combined standard uncertainties.
3.2.15 normalized residual, ζ,n—quotient of a residual, e,
i i
3.2.1.1 Discussion—See Eq 15 in 16.2.15.
and its combined standard uncertainty, u (e)
c i
3.2.15.1 Discussion—See Appendix X5 for the calculation
3.2.2 background subtraction count (BSC), n—a source
and use of ζ.
count used to determine the background to be subtracted from i
the sample test source count.
3.2.16 operating parameter, n—any of the configurable
settings of a nuclear counting instrument, such as a detector
3.2.3 calibration, n—determination of an instrument’s re-
operating voltage, amplifier gain, or energy discriminator
sponse to a known amount of radioactive material.
setting.
3.2.3.1 Discussion—Instrument calibrations may include
3.2.17 quality manual (QM), n—a document stating the
calibrations for counting efficiency, gain, and resolution.
management policies, objectives, principles, organizational
3.2.4 calibrationsource,n—aknownquantityofradioactive
structureandauthorities,accountability,andimplementationof
material, prepared and configured for calibrating nuclear in-
a laboratory’s quality system, to assure the quality of its data.
struments.
3.2.17.1 Discussion—The quality manual shall document
3.2.4.1 Discussion—Acalibration source used for efficiency
the process by which appropriate analytical methods are
calibration must have quantity values and uncertainties with
selected, their capability is evaluated, and their performance is
documented traceability to the SI.
documented. The analytical methods manual and standard
3.2.5 certified calibration source (CCS), n—a calibration
operating procedure manuals shall be part of but not necessar-
source (see 3.2.4) accompanied by a certificate that provides ily included in the quality manual. The quality manual or
the values, uncertainties, and reference date of the source’s
standard operating procedures, or both, shall also include
primary radioactive constituents, with documentation of met-
instructionsthatprescribecorrectiveaction,forexample,inthe
rological traceability to the SI.
event of a failure of an instrument check source (ICS),
3.2.5.1 Discussion—ANSI N42.22 describes the required
instrumentcontaminationcheck(ICC),orbackgroundsubtrac-
content of the certificate and presents criteria for ensuring
tion count (BSC).
traceability of radionuclide sources to NIST.
3.2.18 relative residual, %∆,n—quotient of a residual, e,
i i
3.2.6 continuing instrument quality control, n—activities and the corresponding predicted value, ɛˆ, typically expressed
i
as a percentage.
conducted to ensure that an instrument continues to respond in
the same manner after its calibration.
3.2.19 relative standard deviation (RSD), n—ratio of the
standard deviation to the mean (also known as coeffıcient of
3.2.7 instrument check, n—a test of the response of a
variation).
nuclear counting instrument, typically using an instrument
3.2.19.1 Discussion—See Practice E2586.
check source (see 3.2.8) and including some combination of
tests of efficiency, energy calibration, and peak resolution as
3.2.20 residual, n—difference between the observed value
appropriate for the instrument type.
of the dependent variable, ɛ, and the corresponding predicted
i
value, ɛˆ.
3.2.8 instrument check source (ICS), n—a radioactive i
source,notnecessarilytraceabletoanystandard,thatisusedto 3.2.21 sample test source (STS), n—a sample or sample
test the response of a nuclear instrument. aliquot prepared or configured for measurement of its emitted
radiation.
3.2.9 instrument contamination check (ICC), n—a measure-
3.2.22 tolerance limit, n—a limit established to evaluate the
ment to determine if a nuclear instrument is contaminated with
acceptability of a monitored process parameter.
radioactive material.
3.2.23 working calibration source (WCS), n—a calibration
3.2.10 instrument control chart, n—a chart used to monitor
source (see 3.2.4) diluted or prepared by the laboratory from
and evaluate the performance of an instrument using predeter-
radioactive reference materials.
mined statistically based limits.
3.3 Acronyms:
3.2.11 instrument tolerance chart, n—a chart used to moni-
3.3.1 ADC—analog-to-digital converter
tor and evaluate the performance of an instrument using
tolerance limits appropriate to the method, scope of work, and
3.3.2 AVR—acceptable verification ratio
data quality requirements.
3.3.3 BIPM—Bureau International des Poids et Mesures
3.2.12 known value (KV), n—accepted true value of the (English: International Bureau of Weights and Measures)
analyte activity added to a verification sample.
3.3.4 BSC—background subtraction count
3.2.12.1 Discussion—See Eq 13 in 16.2.13.
3.3.5 CCS—certified calibration source
3.2.13 measured value (MV), n—result of a measurement
performed on a verification sample.
The boldface numbers in parentheses refer to the list of references at the end of
3.2.13.1 Discussion—See Eq 11 in 16.2.11. this standard.
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D7282 − 21
3.3.6 DF—decay factor 5.4 The data obtained while following this practice will
likely be stored electronically. The data remain in electronic
3.3.7 FWHM—full width at half maximum
storage, where they are readily available to produce plots,
3.3.8 ICC—instrument contamination check
graphs, spreadsheets, and other types of displays and reports.
3.3.9 ICS—instrument check source
The laboratory QM should specify the frequency and perfor-
3.3.10 KV—known value mance of data storage backup.
3.3.11 LCS—liquid scintillation counter
6. Hazards
3.3.12 MV—measured value
6.1 The vendor-supplied safety instructions and laboratory
3.3.13 MQO—measurement quality objective
safety regulations should be consulted before using electronic
3.3.14 NIST—National Institute of Standards and Technol-
and electrical equipment.
ogy
6.2 Corrosive, flammable, reactive, and toxic materials may
3.3.15 NMI—National Metrology Institute
beusedwhenperformingsomestepsinthispractice.Beaware
3.3.16 QC—quality control ofhazardsinvolvedwithallmaterialsandprocessesemployed,
and comply with any and all applicable health and safety
3.3.17 QM—quality manual
procedures, plans, and regulations. Safety data sheets are a
3.3.18 RSD—relative standard deviation
source of information.
3.3.19 STS—sample test source
INSTRUMENT SETUP
3.3.20 WCS—working calibration source
7. Scope
4. Summary of Practice
7.1 Instructions are provided for initial setup of instruments
4.1 This practice summarizes information and guidance for
usedforactivitymeasurements.Theseinstructionsmayalsobe
setup, calibration, and quality control for nuclear counting
applied when the operating parameters of an instrument are
instruments. The procedure is divided into four main sections:
being reestablished.
Introduction Sections 1 through 6
Instrument set-up Sections 7 through 9
8. Significance and Use
Initial instrument quality control Sections 10 through 13
Calibration Sections 14 through 19
8.1 Successful setup of an instrument and its subsequent
Continuing instrument quality control Sections 20 through 25
routine use depend, at least in part, on how well the manufac-
4.2 Specific information about setup, calibration, and qual-
turer’s instructions are written and followed. Thus, the manu-
ity control for the four types of instruments is presented in the
facturer’srecommendationsareanintegralpartofthisprocess.
sections listed below.
Success also depends on how well the laboratory has planned,
Quality
developed, and documented its own protocol for instrument
Instrument Type Setup Calibration
Control
use and how well personnel are trained.
Gas proportional counter 9.1 16 22
Gamma-ray spectrometer 9.2 17 23
Alpha-particle spectrometer 9.3 18 24
9. Instrument Setup Procedures
Liquid scintillation counter 9.4 19 25
9.1 Gas Proportional Counter Setup:
5. Significance and Use
9.1.1 Upon initial setup, after major repair or service, or
when QC results indicate the need to adjust operating param-
5.1 This practice is consistent with a performance-based
eters for an instrument, measure a suitable radioactive source
approach wherein the frequency of recalibration and instru-
asspecifiedinthelaboratoryQMormanufacturer’sprotocolto
menttestingislinkedtotheresultsfromcontinuinginstrument
confirm that the instrument responds according to QM or
qualitycontrol.Underthepremiseofthispractice,alaboratory
manufacturer’s specifications. The instrument setup and cali-
demonstrates that its instrument performance is acceptable for
bration records should be maintained per applicable record
analyzing sample test sources.
requirements. ISO/IEC 17025 includes information regarding
5.2 When a laboratory demonstrates acceptable perfor-
the type of records to retain.
mance based on continuing instrument quality control data
9.1.2 Iftheinstrumentbeingconfiguredhaspreviouslybeen
(that is, control charts and tolerance charts), batch QC samples
used to generate sample test source results, the “as-found”
(that is, blanks, laboratory control samples, replicates, matrix
instrumentsettings(thatis,operatingvoltageanddiscriminator
spikes, and other batch QC samples as may be applicable) and
settings) should be recorded and compared to previous “as-
independent reference materials, traditional schedule-driven
left” parameters to ensure that instrument configuration has
instrument recalibration is permissible but unnecessary.
been maintained. If the instrument configuration has changed,
5.3 When continuing instrument QC, batch QC, or indepen- an investigation into the potential impact of the changes shall
dent reference material sample results indicate that instrument be conducted and appropriate corrective action taken.
response has exceeded established control or tolerance limits, 9.1.3 Set the appropriate instrument operating parameters
instrument calibration is required. Other actions related to for the intended measurements. For example, acquire voltage
sample analyses on the affected instruments may be required plateaus and establish the alpha or beta, or both, plateau
by the laboratory QM. operating voltages, and alpha or beta, or both, discriminator
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D7282 − 21
settings (that is, adjust for crosstalk). The instrument configu- instrument settings (for example, detector bias) should be
ration should be optimized for the intended applications. For recorded and compared to previous “as-left” parameters to
example, when measuring evaporated sample solids deposited ensure that instrument configuration has been maintained. If
ina50.8mm(2-inch)diameterplanchet,itmaybedesirableto the instrument configuration has changed, an investigation into
perform voltage plateaus and optimize discriminator settings
the potential impact of the changes shall be conducted and
using a geometry and radionuclide similar to those that will be appropriate corrective action taken.
used for subsequent measurements (for example, a 50.8 mm
9.3.3 Establish the energy range for the spectrometer to
diameter Th source rather than a point source contain-
includeallalphaemissionenergiesofinteresttothelaboratory.
ing Po). If setup procedures deviate from those recom-
Adjust the amplifier gain andADC range, or equivalent digital
mended by the manufacturer, the procedures shall be specified
spectrometer settings, to establish the desired energy per
indetailinthelaboratoryQM.Operatingparametersshouldbe
channel relationship. When the instrument operating param-
set to produce consistency in performance across multiple
eters are satisfactorily established, record the instrument set-
detectors used for a common application.When the instrument
tings for future reference.
operating parameters have been established, record the “as-
9.4 Liquid Scintillation Counter Setup:
left” instrument settings for future reference.
9.4.1 Upon initial setup, after major repair or service, or
9.2 Gamma-Ray Spectrometer Setup:
when QC results indicate the need to adjust operating param-
9.2.1 Upon initial setup, after major repair or service, or
eters for an instrument, measure a suitable radioactive source
when QC results indicate the need to adjust operating param-
asspecifiedinthelaboratoryQMormanufacturer’sprotocolto
eters for an instrument, measure a suitable radioactive source
confirm that the instrument responds according to QM or
asspecifiedinthelaboratoryQMormanufacturer’sprotocolto
manufacturer’s specifications (for example, detector efficiency,
confirm that the instrument responds according to QM or
background for region of interest for beta or alpha applica-
manufacturer specifications (for example, full-width-at-half-
tions). The instrument setup and calibration records should be
maximum resolution, peak-to-Compton ratio, and detector
maintainedperapplicablerecordrequirements.ISO/IEC17025
efficiency). The instrument setup and calibration records
includes information regarding the type of records to retain.
should be maintained per applicable record requirements.
9.4.2 Iftheinstrumentbeingconfiguredhaspreviouslybeen
ISO/IEC 17025 includes information regarding the types of
used to generate sample test source results, the “as-found”
records to retain.
instrument settings (for example, counting channels or energy
9.2.2 Iftheinstrumentbeingconfiguredhaspreviouslybeen
windows) should be recorded and compared to previous
used to generate sample test source results, the “as-found”
“as-left”parameterstoensurethatinstrumentconfigurationhas
instrument settings (that is, detector bias, amplifier gain,
been maintained. If the instrument configuration has changed,
analog-to-digital converter (ADC) range, or equivalent digital
an investigation into the potential impact of the changes shall
spectrometer settings) should be recorded and compared to
be conducted and appropriate corrective action taken.
previous “as-left” parameters to ensure that instrument con-
figuration has been maintained. If the instrument configuration
9.4.3 Set the instrument operating parameters for the in-
has changed, an investigation into the potential impact of the
tended measurements according to the manufacturer’s recom-
changes shall be conducted and appropriate corrective action
mendations. For example, establish the photomultiplier oper-
taken.
ating voltage, discriminator settings, and energy-range
9.2.3 Settheenergyrangeforthespectrometertoincludeall
windows as applicable to the measurements to be performed.
gamma emission energies of interest to the laboratory. Adjust
When the instrument operating parameters are satisfactorily
the amplifier gain,ADC range, or equivalent digital spectrom-
established, record the instrument settings for future reference.
eter settings to produce the desired energy per channel rela-
INITIAL INSTRUMENT QUALITY CONTROL
tionship. When the instrument operating parameters are satis-
factorily established, record the instrument settings for future
10. Scope
reference.
9.3 Alpha-Particle Spectrometer Setup:
10.1 Quality control should be initiated before or during
9.3.1 Upon initial setup, after major repair or service, or instrument calibration to confirm the instrument’s operability
when QC results indicate the need to adjust operating param- and stability and to establish the continuing quality control
eters for an instrument, measure a suitable radioactive source parameters. The purpose of the instrument quality control is to
asspecifiedinthelaboratoryQMormanufacturer’sprotocolto
verify that the instrument’s metrological characteristics are (1)
confirm that the instrument responds according to QM or acceptable for analysis of sample test sources and (2) equiva-
manufacturer’s specifications (for example, bias voltage
lent to those that existed during calibration. Continuing instru-
setting, full-width-at-half-maximum resolution, detector effi- ment quality control results are compared to control limits or
ciency and background). The instrument setup and calibration
tolerance limits or are evaluated by other statistical tests to
records should be maintained per applicable record require- establish acceptability. Instrument quality control uses perfor-
ments.ISO/IEC17025includesinformationregardingthetype
mance checks that include, but are not limited to, background
of records to retain. stability, detector response (count rate) reproducibility with a
9.3.2 Iftheinstrumentbeingconfiguredhaspreviouslybeen known ICS, gain stability, and peak resolution stability, as
used to generate sample test source results, the “as-found” appropriate to each type of instrument.
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D7282 − 21
11. Significance and Use 12.1.2 LiketheICS,theICCdoesnotreflecteverycounting
configuration on an instrument used for different tests. It
11.1 Guidanceisprovidedinthissectionforestablishingthe
should be configured, however, to ensure effective identifica-
manner in which instrument performance parameters shall be
tion of gross contamination of the instrument.
monitored. These performance parameters should be estab-
12.1.3 The BSC must be closely matched to its associated
lished prior to or concurrent with counting calibration samples
sample test source configuration to ensure that the measure-
and shall be established before counting sample test sources.
ments used for background subtraction accurately reflect con-
Two primary tools for monitoring instrument performance are
ditionswhencountingsampletestsources.TheBSCiscounted
the control chart and the tolerance chart. Instrument quality
to determine the value to use for subtraction from the sample.
controlprotocolsshallbeclearlydefinedinthelaboratoryQM.
The BSC should be counted as long as or longer than the
11.2 Instrument control charts are used to monitor those
longest sample test source count. Although the BSC and ICC
continuing instrument performance parameters where statisti-
may be counted in the same test source configuration for the
cal control is necessary to ensure the quality of the reported
same length of time, the ICC is a holder for the sample test
sample test source result. For those performance parameters
sourcethatisfreeoftheanalyte(thatis,emptyplanchetforgas
where statistical control is not necessary but where exceeding
proportional counting or a sample holder with a filter for alpha
athresholdvaluemayimpactthequalityorusabilityofsample
spectrometry or an empty chamber or Marinelli beaker for
test source results, a tolerance chart may be used. The
gamma spectrometry), which is counted for a shorter time than
laboratoryQMshallindicatetheappropriatetool,controlchart
the BSC. The laboratory’s QM shall specify the frequency and
ortolerancechart,formonitoringeachperformanceparameter.
protocol for the ICC and BSC.
11.3 The limits for any chart that is used to test for changes
12.1.4 Radioactive isotopes in the container or sample
in a calibrated parameter, such as counting efficiency or gain,
mounting materials may contribute to the overall method
should be established at the time of calibration. The limits
background and must be accounted for to ensure accurate
should not be changed afterwards except for decay correction
background correction.
when appropriate, or as described in 12.1.5, 12.2, and 12.3,
12.1.5 The false-alarm rates for control charts can vary
unless the calibrations are repeated.
significantly if the control limits are based on small data sets.
11.4 Instrument QC is linked to measurement uncertainty.
If the laboratory has a large number of such control charts,
(1)Any assumptions made about the instrument’s performance
evenifalltheinstrumentsareequallystable,itwilllikelyseem
forQCpurposes,suchasassumptionsaboutcountingstatistics,
that some charts remain consistently in control while others go
variability of backgrounds, efficiencies, or reproducibility of
out of control frequently. For this reason, if the initial data set
source placement, should be consistent with those made when
is small, the limits should be updated when more data points
evaluating measurement uncertainties. (2) The rigor of the QC
are available. Such an update should be performed at most
regimen should be appropriate for the required uncertainty of
once per chart and as soon as practical after the required
sample measurements or other measurement quality objectives
number of points are obtained.
(MQOs).Forexample,thechoiceofcontrolchartsortolerance
12.1.6 AlthoughsomeQCsoftwaresystemsprovideoptions
chartsmaybebasedpartlyontheuncertaintyrequirements.(3)
for continually updating control limits, these options should
Instrument QC provides a large body of data that may often be
not be used when monitoring calibrated parameters, since
used to evaluate uncertainty components that might otherwise
doing so could allow instrument performance to drift after
be difficult to estimate—for example, variability of back-
calibration without ever triggering an alarm.
grounds or efficiencies.
12.2 Calculate the mean and standard deviation of the
12. Establishing the Control Chart
measured parameter using equations appropriate for the ex-
12.1 Using the appropriate ICS or ICC, perform at least 7
pected type of distribution. For example, if the counting
measurements of the performance parameter to be monitored,
statistics are believed to be approximately Poisson and the
ensuring that the measurement conditions are reproducible and
parameter is based on a radionuclide that will decay measur-
match the sample analysis conditions as closely as possible.
ably during the life of the chart, calculate a mean decay-
These measurements may be performed sequentially over a
ˆ
corrected count, C, and estimate the mean, µˆ , and standard
C
short period of time but should span at least a 24 h period. In
deviation, σˆ , for a future measurement of the same source as
C
each case, the ICS or ICC should be removed from the
follows.
instrument between measurements and re-inserted so that the
n
control chart reflects variability in sample positioning.
C
( i
i51
12.1.1 Foreachinstrumentperformanceparameterthatuses
ˆ
C 5 (1)
n
a radioactive source, accumulate sufficient net counts to obtain
DF
( i
i51
a relative standard counting uncertainty <1% (10000 net
counts minimum). Since a single instrument can be used for
ˆ
µˆ 5 C·DF (2)
C
manydifferenttests,theICSusedtomeasuredetectorresponse
99 2
=
σˆ 5 µˆ 1~ξ µˆ ! (3)
may be dissimilar to calibration sources (for example, Tc
C C r C
source for gas proportional counting units, unquenched tritium
where:
foraliquidscintillationcounter,oramulti-nuclidepointsource
ˆ
C = estimated mean decay-corrected count,
for gamma spectrometry systems).
´1
D7282 − 21
eters and be able to compare individual observations with the
n = number of measurements used to set up the chart,
established warning and control limits and advise the operator
C = observed count during the ith measurement,
i
of performance warnings and failures. The software must be
DF = decay factor for the ith measurement,
i
µˆ = estimated mean count for the future measurement, documented as specified in the laboratory QM.
C
DF = decay factor for the future measurement,
13. Instrument Tolerance Charts
σˆ = estimated standard deviation for the future
C
measurement, and
13.1 Thepurposeoftolerancechartsistocompareobserved
ξ = tolerable additional non-Poisson relative standard de-
r
instrument performance to acceptable performance limits. A
viation (consistent with the uncertainty model for
tolerance may be expressed as a percent (%) deviation of an
sample measurements—may be zero).
observed parameter from a nominal value, which might be an
estimated mean, calibrated value, or other assumed target
12.2.1 If the initial limits are based on fewer than 15
value. There may be different tolerances for values above and
(preferably 20) measurements, update the limits when 15 (or
belowthenominalvalue.Thebasisforthetolerancesmayalso
20) data points have been obtained.
betakenfromtheMQOsassociatedwithaprojectorstatement
12.3 If Poisson statistics cannot be assumed, one may
of work.
estimate the mean and standard deviation as follows.
13.2 Tolerance limits differ from control limits in that they
n
¯
are not based on statistical measures, but instead are based on
µˆ 5 C 5 C (4)
C i
(
n
i51
acceptance criteria appropriate to the method and scope of
n
work. (The QM shall define the basis and manner by which
n 2 0.75 1
‾ 2
σˆ 5 Œ ~C 2 C! (5)
C ( i tolerance limits are established for each performance param-
n 2 1 n 2 1
i51
eter).Atolerancechart,similartoacontrolchart,isagraphical
12.3.1 If the initial limits are based on fewer than 20
tool that can be used to evaluate instrument performance and
(preferably 30) measurements, update the limits when 20 (or
trending of instrument parameters. In Reference (1), Chapter
30) data points have been obtained.
18, several examples are given for the use of tolerance limits,
one of which is monitoring the resolution of a high-purity
12.4 An alternative estimator for the standard deviation is
germanium detector. In addition, it may be appropriate to
given by:
establish “warning limits” when using a tolerance chart to
n21
=π
ensure appropriate actions are taken before a tolerance limit is
σˆ 5 C 2 C (6)
C ( ? i11 i?
2~n 2 1!
i51 crossed.
13.3 For each performance parameter to be charted, estab-
12.4.1 The estimator given by Eq 6 is somewhat less
lishthetolerancelimits.Thetolerancelimitsshouldbeselected
sensitive to outliers than the one given by Eq 5. For normally
so that operation of the instrument just within the limits will
distributed data without outliers, Eq 5 tends to outperform Eq
not adversely affect the performance of the test or method.
6.
Account for radioactive decay as appropriate when evaluating
12.5 Create a control chart with the observed result on the
parameters based on short-lived radionuclides.
vertical axis and the observation number or date on the
13.4 Performastatisticalanalysisofaseriesofobservations
horizontal axis. Draw a horizontal line or a sloping (decay-
of the parameter to ensure that the tolerance limits are
corrected)curveonthecharttorepresentthepredictedmeanof
achievable. If the standard deviation of the observed values
theobservedvalues.Drawlinesorcurvesforthecontrollimits
exceeds one-third of the required tolerance, either improve the
at three standard deviations above and below the mean.
measurementprecisiontoanacceptablelevel,orreconsiderthe
Additional lines or curves for “warning limits” should also be
size of the tolerance itself. The consequence of not doing so
drawn, typically at two standard deviations above and below
wouldbeanexcessivefrequencyofout-of-tolerancesituations.
themean.Thequalitycontroldatashouldbeevaluatedtocheck
that they follow the expected distribution—for example, Pois-
13.5 Createatolerancechartwiththeobservedresultonthe
son or normal—and that there are no outliers. Appendix X6
vertical axis and the observation number or date on the
describesproceduresthatmaybeusedtotesttheassumptionof
horizontalaxis.Drawahorizontallineonthecharttorepresent
Poissoncountingstatistics.Reference (1)includesadiscussion
the nominal value of the observed parameter, and draw
forpursuingroot-causeanalysisofexcursions(departuresfrom
horizontal lines for the tolerance limits above and below the
the expected condition). Practices D3648 and Reference (1),
nominal value. It can also be informative to draw horizontal
Chapter 18, present information on the preparation and inter-
lines for the 3-sigma statistical control limits, although these
pretation of control charts.
3-sigma limits will not be used to accept or reject observed
parameter values. The 3-sigma limits may be used instead to
12.6 Many instruments are provided with operation and
provide early warnings of trends that might eventually impact
analysis software that may include performance check and QC
data quality.
chartingcapabilities.Standalonechartingsoftwaremayalsobe
used. It is not necessary that the software use exactly the same 13.6 Many instruments are provided with operation and
terminologyorgraphicalfeatures.However,ifsoftwareistobe analysis software which may include performance check capa-
used for continuing instrument quality control, it must support bilities. It is not necessary that the software use exactly the
the statistical evaluation of the necessary performance param- same terminology or graphical features. However, if the
´1
D7282 − 21
software is to be used for continuing instrument tolerance 16.2.4 Ablanksampleshallalsobeprocessedinassociation
checks, it must be able to compare individual observations to withtheWCSs.Theblanksampleresultshouldbecomparedto
the established tolerance limits and indicate out-of-tolerance the performance criteria stated in the laboratory’s QM.
conditions. Standalone charting software can also be used for 16.2.5 The activity of each WCS should be selected to
this purpose.The software must be documented as specified in
produce a count rate not exceeding 5000 counts per second
–1
the laboratory QM. (s ). It is essential that the count rate of the WCS be low
enough to avoid instrument dead time that would result in lost
CALIBRATION
counts.
–1
NOTE 1—The limitation of 5000 counts per second (s ) was based on
14. Scope
typical usage and may vary according to instrument type and manufac-
14.1 The calibration process establishes the response of an turer. Users should consult the manufacturer’s specifications.
instrument to calibration sources. The calibration sources shall
16.2.6 The laboratory QM shall state the uncertainty re-
have values (with uncertainties) that are traceable to the SI via
quirements for the measurement. The WCS should be counted
a national metrology institute. When working calibration
long enough to obtain a relative standard counting uncertainty
sources are used, they shall be prepared from certified SI-
<1% (10000 net counts minimum).
traceable radionuclide standards.
16.2.7 CorrecttheWCSactivityforradioactivedecay(from
the reference time to the time of the measurement). Calculate
15. Significance and Use
the counting efficiency, ε , using the equation defined in the
WCS
laboratory QM or with example Eq 7.
15.1 Calibration of a gas proportional counter, gamma
spectrometer,alphaspectrometer,andliquidscintillationcoun-
R 2 R
a b
ε 5 (7)
WCS
ter is addressed in the following sections.
A ·Y ·DF
WCS WCS
15.2 Consult Practices D3648 for information regarding the
where:
use of instruments for performing radioanalytical measure-
ε = single point efficiency of WCS (counts per second
WCS
ments. –1 –1
per becquerel (s Bq ),
–1
R = count rate (s ) of WCS,
15.3 Efficiency calibration acceptance criteria are provided
a
–1
R = count rate (s ) of instrument background,
in this practice for gas proportional counting, gamma b
A = activity (Bq) of the WCS at the reference date and
WCS
spectrometry, alpha spectrometry, and liquid scintillation
time of the calibration source,
counting instruments. Achievement of performance like that
Y = chemical yield of the WCS, if applicable,
WCS
specified in standards such as ANSI N42.23, ANSI/HPS
DF = decay factor for the calibrating radionuclide
N13.30, and References (1) and (2) is more likely when the
2λ t 2t
~ !
1 0
e ,
calibration acceptance criteria in this practice are met or
λ = ~ln 2! ⁄ T , where T denotes the half-life of cali-
1/2 1/2
exceeded.
brating radionuclide (half-life units must match
those used for the difference t –t ),
1 0
16. Gas Proportional Counter Instrument Calibrations
t = reference date and time of the calibrating radionu-
16.1 Refer to the guidance in Sections 7 to 13 for counting
clide activity value, and
t = start of WCS count (date and time).
the ICS and ICC at instrument setup in preparation for
calibration.Forthoseinstrumentsalreadyinuse,counttheICS
16.2.7.1 Eq 7 accounts for the total efficiency of the
and ICC samples as prescribed in Section 22.
radionuclide even when the probability of alpha or beta
16.2 Single-Point Effıciency or Constant Test Mass for a emission per decay is less than 1.0 (less than 100%).
Specific Radionuclide: 16.2.7.2 Calculate the combined standard uncertainty
u ε , using the equation defined in the laboratory QM or
~ !
16.2.1 Instructions for a single-point efficiency calibration c WCS
with example Eq 9.
of a gas proportional counter are provided below. A single-
pointefficiencyisusedwhentheefficiencychangeisnegligible
R ⁄ t 1R ⁄ t
a a b b
u ~ε ! 5
over the expected mass range for the test. F
c WCS 2
~A ·Y ·DF!
WCS WCS
(8)
16.2.2 The guidance below assumes the use of working 2 2 1⁄2
u A u Y
~ ! ~ !
WCS WCS
2 2
1ε 1 1φ
calibration sources (WCSs). To control possible bias due to S DG
WCS 2 2 G
A Y
WCS WCS
non-representative calibration sources, the preparation method
where:
of the WCSs should produce sources that are as equivalent as
practicable to the sample test sources. Since the preparation u (ε ) = the combined standard uncertainty of the single
c WCS
typically involves chemical procedures, with opportunities for point efficiency ε ,
WCS
loss of analyte, it is essential that the procedure be designed t = duration of count for WCS,
a
t = duration of count for the background,
andperformedcarefullytoensureitsquantitativenatureandto
b
u(A ) = the standard uncertainty of A ,
preserve traceability to the SI. WCSs shall be prepared from WCS WCS
u(Y ) = the standard uncertainty of Y , and
WCS WCS
certified SI-traceable radionuclide standards.
φ = relative standard deviation of the efficiency due
G
16.2.3 A minimum of three WCSs (or one CCS) shall be
to source-to-source variability.
used.
´1
D7282 − 21
NOTE 2—The other symbols are as defined for Eq 7.
2 2
R ⁄t 1R ⁄t u ε u Y
~ ! ~ !
a a b b
u MV 5Π1MV 3 1 (11)
~ ! S D
c 2 2 2
16.2.7.3 Correction for decay during counting may be made
~ε ·Y·DF! ε Y
by multiplying DF by the value, DF , obtained using Eq 10.
a
where:
2λt
a
1 2 e sinh λt ⁄2
~ !
a
2λt ⁄2 u (MV) = the combined standard uncertainty of the mea-
a
DF 5 5 e (9) c
a
λt λt ⁄2
a a
sured value, in Bq,
t = duration of count for the verification sample,
where: a
t = duration of count for the background,
b
λ = decay constant of the radionuclide, and
u(ε) = the standard uncertainty of ε, and
t = duration of count.
a
u(Y) = the standard uncertainty of Y.
NOTE 3—The two expressions above for DF are theoretically equiva-
a
NOTE 4—The other symbols are as defined for Eq 11.
lent; however, the second expression involving the hyperbolic sine
function,sinh,shouldgivemoreaccuratefloating-pointresultswhen λt is
a
16.2.12.1 TheuncertaintycomponentsincludedinEq12are
very small, in which case DF is also approximated very well by the
a
expected to be potentially significant. Other components such
−λt
a/2
simpler factor e .
as those due to WCS preparation, reagent preparation, and
16.2.8 See Appendix X5 for guidance on the calculation of
radionuclide half-life should be included whenever they are
aweightedaverageanditsuncertainty,andforassessingthefit
consideredsignificant.Furthermore,itisrecommendedthatthe
ofthecalibrationdata.Thetotalcalibrationuncertaintyshallbe
user evaluate the possibility that there may be correlations
included in the combined standard uncertainty of each sample
between some input estimates, which affect the combined
result.
standard uncertainty. For additional information on the evalu-
16.2.9 Verify the single-point efficiency calibration before
ation and expression of measurement uncertainty refer to
use by analyzing one sample that contains the same radionu-
JCGM 100:2008 or Reference (3).
clide prepared from a second certified SI-traceable standard. If
16.2.13 Calculate the known value, KV, using the equation
obtaining a second certified standard is impractical, a separate
defined in the laboratory QM or with Eq 13.
dilutionoftheoriginalradionuclidestandardshallbeused,and
KV 5 AC·V (12)
thisfactshallbedocumentedappropriately.ThelaboratoryQM
shall state the uncertainty requirements for the verification
where:
measurement. See 16.2.5 and 16.2.6 for additional limits on
KV = known value of the activity added to the verification
count rate and counting uncertainty.
sample,
16.2.10 A blank sample should be analyzed with the veri-
AC = activity concentration in becquerels per litre (Bq/L) of
fication sample. Compare the blank sample result to the
the radioactive reference material used to prepare the
performance criteria stated in the laboratory QM.
verification sample (or massic activity in becquerels
16.2.11 Calculatetheverificationsampleactivity,MV,using
per gram), and
the equation defined in the laboratory QM or with example Eq
V = volume (or mass) of the reference material used.
11.
16.2.14 Calculate the combined standard uncertainty,
R 2 R
a b
u (KV)usingtheequationdefinedinthelaboratoryQMorwith
c
MV 5 (10)
ε·Y·DF
Eq 14.
where:
2 2 2 2
=
u ~KV! 5 V u ~AC!1AC u ~V! (13)
c
MV = measured value (Bq) of the verification sample,
–1
where:
R = count rate (s ) of verification sample,
a
–1
R = count rate (s ) of instrument background, (the net u (KV) = combined standard uncertainty of the activity (Bq)
b c
count rate of the blank sample should be subtracted
added to the verification sample (KV),
u(AC) = standard uncertainty of the activity concentration
alsoifitissignificantwhenevaluatedaccordingtothe
laboratory’s performance criteria), of the radioactive reference material used to pre-
ε = detection efficiency (see Eq 7 and 16.2.7), pare the verification sample, in becquerels per litre
Y = chemical yield of the verification sample, if
(Bq/L), and
applicable,
u(V) = standarduncertaintyofthevolumeofthereference
2λ~t 2t !
1 0
DF = decay factor for the calibrating radionuclide e ,
material used.
λ = (ln 2)/T , where T denotes the half-life of calibrat-
1/2 1/2 NOTE 5—The other symbols are as defined in Eq 13.
ingradionuclide(half-lifeunitsmustmatchthoseused
16.2.14.1 Refer to the statement on uncertainty in 16.2.12.1
for the difference t –t ),
1 0
after Eq 12.
t = referencedateandtimeofthecalibratingradionuclide
16.2.15 The calculated (measured) value of this sample
activity value, and
should agree with the known value of the sample within the
t = start of verification sample count (date and time).
uncertainty of the known and the uncertainty of the sample
16.2.11.1 To correct for decay during counting, refer to Eq
(including the calibration uncertainty) using Eq 15, the accept-
10.
able verification ratio (AVR):
16.2.12 Calculate the combined standard uncertainty
KV 2 MV
? ?
u ~MV!, using the equation defined in the laboratory QM or
c
AVR 5 #2.0 (14)
2 2
with example Eq 12. =u KV 1u MV
~ ! ~ !
c c
´1
D7282 − 21
where: Calculate the individual WCS efficiencies (ε ) using the
WCS
equation defined in the laboratory QM or with example Eq 16.
KV = known value of the activity added to the verifica-
tion sample,
R 2 R
a b
ε 5 (15)
MV = measured value of the verification sample as WCS
A ·Y ·DF
WCS WCS
calculated with Eq 11,
where:
u (KV) = combined standard uncertainty of the known
c
–1
ε = single-point measured efficiency of the WCS (s
value, and
WCS
–1
u (MV) = combined standard uncertainty of the measured
Bq ),
c
–1
R = count rate (s ) of WCS,
value.
a
–1
R = count rate (s ) of instrument background,
NOTE 6—This equation is similar to the one used in Reference (1),
b
Chapter 18, to assess results from laboratory control samples.A“z” value
A = activity (Bq) of the WCS at the reference date and
WCS
of 2 is typical; however other “z” values may be used.
time of the calibration source,
Y = chemical yield of the WCS, if appropriate,
WCS
16.2.15.1 Refer to the statement on uncertainty in 16.2.12.1
DF = decay factor for the calibrating radionuclide,
...