- Количество слайдов: 92
Hopewell Designs, Inc. Calibration of Radiation Instruments Overview, Practical Techniques, Irradiators Illustrated by Robert Rushton 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 Hopewell Designs, Inc.
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 Hopewell Designs, Inc.
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 Hopewell Designs, Inc.
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 Hopewell Designs, Inc.
Gamma Free In Air Hopewell Designs, Inc.
Gamma Beam & Panoramic Irradiators Hopewell Designs, Inc.
Panoramic Dosimeter Irradiator Hopewell Designs, Inc.
Box Calibrator • Self-contained • Typical dual source with attenuator set • 6 orders of magnitude of exposure rates • Built in security (but must be fed) Hopewell Designs, Inc.
Well Irradiator • Good for production calibration • No exposure room req’d • 9 m travel & X 100 attenuator give range of 4 orders of magnitude Hopewell Designs, Inc.
Gamma Well & Control Station Hopewell Designs, Inc.
Small Gamma Irradiator • Self contained • 5 Ci Cs-137 source • For EPDs, PICs, Instrument Probes • 3 Attenuators – 0 to 1000 X Hopewell Designs, Inc.
Am-241 Irradiator • Low energy gamma beam Hopewell Designs, Inc.
Neutron Free In Air Hopewell Designs, Inc.
Pneumatic Neutron/Gamma Irradiator & 4 Positioning Tracks Hopewell Designs, Inc.
Pneumatic Transfer System Hopewell Designs, Inc.
Neutron Well Irradiator Hopewell Designs, Inc.
X-Ray Beam Irradiator Hopewell Designs, Inc.
Beta Beam Irradiator Hopewell Designs, Inc.
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 Hopewell Designs, Inc.
LSI - 4 tracks, below ground source storage Hopewell Designs, Inc.
LSI Basement • Below ground shield for 7 sources • Staircase to basement Hopewell Designs, Inc.
Gamma Beam Irradiator Hopewell Designs, Inc.
Source Transfer Tube for GBI curved to prevent radiation shine Hopewell Designs, Inc.
Source Holders - “Rabbits” Hopewell Designs, Inc.
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 Hopewell Designs, Inc.
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 Hopewell Designs, Inc.
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 Hopewell Designs, Inc.
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 k. V X-Rays Hopewell Designs, Inc.
Radiation Interactions and Dosimetry Group • 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. Hopewell Designs, Inc.
Control Station for Dual X-ray Sets Hopewell Designs, Inc.
300 k. V X-Ray Range Hopewell Designs, Inc.
An Instrument Calibration at NIST X-Ray Calibration Lab • 100 k. V Range • 300 k. V Range • Mammography Range Hopewell Designs, Inc.
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 Hopewell Designs, Inc.
Report for Ion Chamber • • • Shows Raw Data Beam Code Chamber Settings Air Kerma Calibration Factor Hopewell Designs, Inc.
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 Standards Canada’s X-Ray Free Air Chamber Hopewell Designs, Inc.
IAEA Co-60 Ion Chamber Hopewell Designs, Inc.
NIST Wide Angle Free Air Chamber Hopewell Designs, Inc.
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 Hopewell Designs, Inc. Russia Spain USA Italy Japan • United Kingdom • (plus others)
Secondary Standards Labs (SSL) Algeria Argentina Bangladesh Belarus Bolivia Brazil Bulgaria Chile Colombia Cuba Cyprus Czech Republic Denmark Ecuador Egypt Ethiopia Finland Georgia Ghana Greece Guatemala Hungary India Indonesia Iran Ireland Israel Korea Kuwait Latvia Libya Madagascar Malaysia Mexico Norway Pakistan Peru Philippines Poland Portugal Romania Saudi Arabia Serbia Singapore Hopewell Designs, Inc. Slovak Republic Slovenia South Africa Sudan Sweden Syria Tanzania Thailand Tunisia Turkey Uruguay Venezuela Vietnam
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 1 st 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 Hopewell Designs, Inc.
Intercomparison Results – One Example Hopewell Designs, Inc.
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, Inc.