Calibration of Radiation InstrumentsOverview, Practical Techniques, Irradiators IllustratedbyRobert 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 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 • STEPS • Pull-down menu • Can move to any step in any order • PROCEDURE – defined by user 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 • 9m travel & X100 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 to1000X 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.