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Hopewell Designs, Inc.
Calibration of Radiation Instruments
Overview, Practical Techniques, Irradiators Illustrated
by
Robert Rushton
Hopewell Designs, Inc.
Hopewell Designs, Inc.
OVERVIEW
• Calibration of Instruments
• Irradiators Illustrated
• Chain of Traceability
• NIST
• International Standards
Hopewell Designs, Inc.
Calibration of Instruments
• Steps in a Typical Calibration Procedure
• What Is Important in a Calibration
• Features that Help Improve Calibrations
Hopewell Designs, Inc.
Steps in a Typical Calibration
• Receive instrument and log into system
• Perform as found set of readings, typically 20% & 80% full scale, all scales
• If required, repair instrument
• Calibrate and adjust until it falls within specifications, typically within 10%
• Record to database, prepare report
• Prepare for shipment, log out of system
Hopewell Designs, Inc.
Elements of a Calibration Program
• Equipment
• Personnel
• Training
• Database, Records Keeping
• Procedures
• QA Program
• Traceability and Accreditation
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Why they are important …
• Procedures – drive the overall program
• QA – keeps the program on track
• Training – people make it happen, training shows them how
• Records – documents what is done
Hopewell Designs, Inc.
Calibration on an Irradiator
• Set up irradiator for exposure rate
– Track position
– Source & attenuator selection
– Expose source
• Record data and/or adjust instrument
• Go to next step in procedure
Hopewell Designs, Inc.
Irradiator Control Screen
• System Status
• Exposure Control
• Time
• Setup
• Positioning
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Exposure Rate Linked to Position
• Exposure rate calculates distance, or• Enter desired distance & exposure rate
calculated• Based on polynomial equation
from irradiator calibration
Hopewell Designs, Inc.
Position Instrument on Platform
Box Calibrator Gamma Beam Irradiator
Hopewell Designs, Inc.
One Button Setup
• PROCEDURE – defined by user
• STEPS • Pull-down menu• Can move to any step
in any order
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Control Screen with Instrument Viewing
Hopewell Designs, Inc.
Record Data to Database
• Record As Found / As Left readings & comments
• Use separate database or irradiator’s built-in function
• At completion, print out calibration report
Hopewell Designs, Inc.
Features that Improve Calibration
• Automation helps with:– Control of Irradiator– Automation of Procedures– Data Collection and Analysis– Database Links
• Benefits Include– Improved Accuracy– Higher Throughput– Audit Trail for Records
Hopewell Designs, Inc.
Irradiators Illustrated
• An Overview of Irradiators – from Sterilization to Calibration
• Calibration Irradiators – Types and Isotopes
• A Detailed Look at 2 Types of Irradiators – LSI and GBI at SRS
Hopewell Designs, Inc.
An Overview of Irradiators – from Sterilization to Calibration
Hopewell Designs, Inc.
NAS Radiation Source Use and Replacement Report
• Radiation Sources: Uses and Origins• Radiation Source Risk• Accelerator and Detector Technology• Self-Contained Irradiators• Panoramic Irradiators• Radiotherapy• Industrial Radiography• Well Logging• Implementation Options to Encourage
Replacement of Sources with Alternatives
Hopewell Designs, Inc.
Sterilization Irradiators
• 7 million Ci Co-60
• Electron Beam
• High Dose, High Throughput
• Medical, Increasingly Food
• Approx. 200 worldwide
Hopewell Designs, Inc.
Blood Irradiators
• Prevents transfusion associated graft versus host disease
• Located at most major hospitals
• 100’s in operation
• Self-contained, simple to operate
• Majority use Cs-137
Hopewell Designs, Inc.
X-Ray Blood and Research Irradiators
• No Security Req’d
• Lower Energy Beam
Hopewell Designs, Inc.
Research Irradiators
• Cs-137 irradiation for medical research, Co-60 for higher doses– Cancer research, – Immunology, – DNA damage/repair, – Materials degradation– Space research.
Hopewell Designs, Inc.
Calibration Irradiators
• Calibration of radiation instruments
• Smallest segment of irradiator types in terms of qnty and total isotope activity
• Wide variety of designs and isotopes
Hopewell Designs, Inc.
Calibration Irradiators• Gamma• Box• X-Ray• Neutron
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Gamma Free In Air
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Gamma Beam & Panoramic Irradiators
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Panoramic Dosimeter Irradiator
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Box Calibrator
• Self-contained
• Typical dual source with attenuator set
• 6 orders of magnitude of exposure rates
• Built in security (but must be fed)
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Well Irradiator
• Good for production calibration
• No exposure room req’d
• 9m travel & X100 attenuator give range of 4 orders of magnitude
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Gamma Well & Control Station
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Small Gamma Irradiator
• For EPDs, PICs, Instrument Probes
• 3 Attenuators – 0 to1000X
• Self contained
• 5 Ci Cs-137 source
X3 8/ 4
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Am-241 Irradiator
• Low energy gamma beam
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Neutron Free In Air
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Pneumatic Neutron/Gamma Irradiator & 4 Positioning Tracks
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Pneumatic Transfer System
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Neutron Well Irradiator
Hopewell Designs, Inc.
X-Ray Beam Irradiator
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Beta Beam Irradiator
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A Detailed Look at 2 Types of Irradiators –
LSI and GBI at SRS
• Mechanical & Electrical Design
• Sources and Ranges
• Control System
• Automated Irradiator Software
• Irradiator Calibration, Automated
Hopewell Designs, Inc.
Low Scatter Irradiator
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LSI - 4 tracks, below ground source storage
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LSI Basement
• Below ground shield for 7 sources
• Staircase to basement
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Gamma Beam Irradiator
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Source Transfer Tube for GBI -
curved to prevent radiation shine
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Source Holders - “Rabbits”
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Major Functions of Automation
• Control of Irradiator
• Automation of Procedures
• Data Collection and Analysis
• Database Links
Hopewell Designs, Inc.
Computer Control
• 1 Button Setup
• Exposure Rate Calculation
• Automated Irradiator Calibration
Hopewell Designs, Inc.
Safety Systems
• Fail-Safe Design
• Indicator Lights
• Search & Evict Process
• Door Interlocks
• Emergency Off Switch
• Error Monitoring
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CALIBRATION OF IRRADIATOR• Ion chamber traceable to NIST used to
measure exposure rate
• Measurements made over full range of track for each source/attenuator
• Data reviewed for accuracy and consistency
• Actual data fit to polynomial equation for exposure rate vs. distance.
Hopewell Designs, Inc.
Calibration Set Up
Ion Chamber in Beam Centerline
Electrometer Linked to Computer
Software for Data Collection
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Irradiator Calibration
• Set up parameters• Ion Chamber• Electrometer• Calibration Points• Exposure
Hopewell Designs, Inc.
Positioning Track Set Up
• Number of Distances to Measure• Geometric/Linear• Range
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Automated Irradiator Operation
• Track position set• Electrometer
polled• Exposure
controlled• Data recorded
Hopewell Designs, Inc.
Data Analysis
• Data is fit to polynomial curve
• Parameters and equation stored to database.
Hopewell Designs, Inc.
Chain of Traceability
• Instrument Calibration Labs
• Secondary Level Calibration Labs
• Primary Calibration Labs
Hopewell Designs, Inc.
Secondary Calibration Labs• High level of precision, accuracy, and
error checking
• Single tier traceability to national standard
• In the United States– Univ. of Wisconsin– K&S Associates
• International– Many countries do not maintain primary
standards
Hopewell Designs, Inc.
National Institute of Standards and Technology
• Overview of the Ionizing Radiation Division
• A Detailed Look at the X-Ray Calibration Ranges
• Free Air Chamber – the Primary Standard for 50 to 300 kV X-Rays
Hopewell Designs, Inc.
• Develops, maintains, and disseminates the national measurement standards for the dosimetry of x rays, gamma rays, and electrons
• Engages in research on radiation interactions and effects to meet requirements for new standards and to address the needs of industry, medicine, and government.
Radiation Interactions and Dosimetry Group
Hopewell Designs, Inc.
Control Station for Dual X-ray Sets
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300 kV X-Ray Range
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An Instrument Calibration atNIST X-Ray Calibration Lab
• 100 kV Range
• 300 kV Range
• Mammography Range
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Instrument Calibration Set Up
Free Air Chamber (NIST National
Standard)
Customer’s Ion Chamber
Hopewell Designs, Inc.
Data Collection and Analysis
• 10-15 Readings Taken per Ion Chamber
• Mean and Standard Deviation Calculated
• Correction Factors Calculated & Applied
• Air Kerma, Exposure Rate Calculated for FAC
• R/C Calculated for Ion Chamber
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Report for Ion Chamber
• Shows Raw Data
• Beam Code
• Chamber Settings
• Air Kerma
• Calibration Factor
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Overall Uncertainty Reduced by
• Up to 15 correction factors calculated and applied
• Measurements confirmed via multiple paths
• Precision positioning
• High precision, ultra stable equipment
Hopewell Designs, Inc.
Results in Uncertainties of:
• Primary calibration labs ± 1%
• Secondary labs ± 2-3%
• Calibration labs > 3%
Hopewell Designs, Inc.
National StandardsCanada’s X-Ray Free Air Chamber
Hopewell Designs, Inc.
IAEA Co-60
Ion Chamber
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NIST Wide Angle Free Air Chamber
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International Standards
• A Look at Calibration Labs Around the World
• Intercomparison and Other International Programs
Hopewell Designs, Inc.
A Bit of Background
• About 20-25% of Hopewell Designs work is international
• We researched international calibration and dosimetry programs
• This presentation gives an overview of what we found, and
• Reviews some of the laboratories where we supplied equipment.
Hopewell Designs, Inc.
Primary Standards Laboratories (PSL)
• France
• Germany
• Canada
• Australia
• Austria
• Hungary• Netherlands
• New Zealand
• Russia
• Spain
• USA
• Italy
• Japan
• United Kingdom
• (plus others)
Hopewell Designs, Inc.
Secondary Standards Labs (SSL)
AlgeriaArgentinaBangladeshBelarusBolivia BrazilBulgariaChileColombiaCuba
CyprusCzech RepublicDenmarkEcuadorEgyptEthiopiaFinlandGeorgiaGhanaGreeceGuatemala
HungaryIndiaIndonesiaIranIrelandIsraelKoreaKuwaitLatviaLibyaMadagascar
MalaysiaMexicoNorwayPakistanPeruPhilippinesPolandPortugalRomaniaSaudi ArabiaSerbiaSingapore
Slovak RepublicSloveniaSouth AfricaSudanSwedenSyriaTanzaniaThailandTunisiaTurkeyUruguayVenezuelaVietnam
Hopewell Designs, Inc.
The Bureau International des Poids et Mesures (BIPM)
• Ensures world-wide uniformity of measurements and traceability to International System of Measurements
• Via Convention of the Metre
• Intercomparison Programs
• Measurement Related Research
Hopewell Designs, Inc.
A Brief History – Dosimetry and Nuclear Medicine
• 1950’s – Co-60 teletherapy introduced
• 1960’s – Recognized need for uniform radiation measurements
• 1970’s – Several networks and programs established in int’l arena
• 1980’s – Ongoing support for calibration, training, new program development
Hopewell Designs, Inc.
International Traceability
• PSLs and BIPM provide 1st link in chain of international measurement system
• Direct comparison with PSL’s standards
• BIPM and PSLs provide calibration services to SSLs & others
Hopewell Designs, Inc.
Services for Radioactivity Measurements
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Intercomparison Results – One Example
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Primary Uses of Radiation - Worldwide
• Nuclear Power
• Industrial Processing, Primarily Sterilization
• Medical Diagnostic and Treatment
Hopewell Designs, Inc.
Medical Treatment
• Largest Segment: Cancer Treatment
• Most new cancer cases in developing countries
• On going effort by WHO and others to support nuclear medicine programs
Hopewell Designs, Inc.
Major Role of SSL
• Help assure accurate dosimetry thru:
– Instrument calibration – traceable to a primary standard
– Dosimetry programs: Calibration & QA audits
Hopewell Designs, Inc.
Work of the SSLs
• Maintain Radiation Dosimetry Standards
• Collaborate with hospitals and end users
• Provide services to end users
Hopewell Designs, Inc.
A Short Tour of Recent Work
• Institut Rudjer Boskovic, Croatia
• Institute of Nuclear Physics, Albania
• Kazakhstan Atomic Energy Committee
• Ministry of Health, Kuwait
• Institute of Public Health, Romania
• Radiation Protection Institute of Ireland
Hopewell Designs, Inc.
Institut Rudjer Boskovic, Croatia
• Institute – nuclear research for over 50 yrs
• Provides dosimetry services
• Setting up instrument calibration
Hopewell Designs, Inc.
Co-60 Teletherapy Calibration
Hopewell Designs, Inc.
X-Ray Techniques,Cs-137 Protection Level Cal.
Hopewell Designs, Inc.
Institute of Nuclear Physics, Albania
• Nuclear research
• Dosimetry program
• Instrument calibration program being implemented
Hopewell Designs, Inc.
X-Ray and Cs-137
Calibrations
Hopewell Designs, Inc.
Kazakhstan Atomic Energy Committee
Hopewell Designs, Inc.
Ministry of Health, Kuwait
Hopewell Designs, Inc.
Institute of Public Health, Romania
• Active dosimetry and instrument calibration for over 30 years
• Upgrade Equipment• Adding to Capabilities
Hopewell Designs, Inc.
Radiation Institute of
Ireland
Hopewell Designs, Inc.
Thanks from Hopewell Designs
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