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Routine Process Control. A Radiation processing facility should have the following vital components. Radiation processing facility. Good management . Qualified and experienced operators. Processing record. Quality Manual. Processing record. Should contain information of
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A Radiation processing facility should have the following vital components Radiation processing facility Good management Qualified and experienced operators Processing record Quality Manual
Processing record • Should contain information of • Reception and inspection of product • Unique code identifying each product • Storage environment • Scheduling the irradiation • Loading the product onto the irradiator system • Unloading the irradiated product from the system • Inspection • checking of routine dosimetry, process parameters • Sign-off of any non-conformances • Approval for release and dispatch • Dispatch to the customer
Specifications of the process • The product covered by the specification • The product pattern and relationship between dose at the monitoring position and the dose at the maximum and minimum dose position • The routine dosimeter monitoring position(s) • For gamma irradiation, the relationship between product density, dose and source strength • For electron beam, the relationship between characteristics, conveyor speed, product configuration and dose
Description of the product • The dimensions and density of package • A description of the irradiation container • A description of the conveyor path
Process Control Receipt and inspection of the product Product Storage Routine Dosimetry Product Processing Product Release Post irradiation Inspection
Receipt and inspection of the product • Check for any obvious signs of damage. • Check that the identity of the product matches • the description in the documentation • Check that the amount of material to be • irradiated matches with the amount described in • the paperwork (purchase orders or delivery • note). • Check the product that has been sent for • routine irradiation has been validated for • that process.
Product Storage • Store unirradiated product in an area isolated • from any irradiated product. • Physical separation such as barrier is most • appropriate. • Keep storage conditions appropriate for the • product being irradiated • Pest control if required • Record the storage environment as a part of • the processing records for the product
Product processing-Documentation • Document should be maintained for each • consignment of product and it should be signed • off at each stage of processing through the irradiator • for • Reception and inspection of product • Scheduling the irradiator • Loading the product onto the irradiator system • Unloading the irradiated product form the system • Final inspection including checking of routine • dosimetry and other stored process parameters • Recording of any non-conformances • Approval for release and dispatch • Dispatch to the customer or their courier.
Product loading for irradiation • Use approved loading configurations specified in • approved and documented procedures • Place controlled identification labels • location • date of processing, • Unique codes identifying the irradiation • conditions and batch/lot numbers.
Use of Radiation sensitive indicators • Radiation sensitive indicators may be used to • show that the product containers have been • irradiated. • Radiation sensitive indicators should be used as • only qualitative indicators of irradiation. • Routine dosimetry of each and every run is • essential in order to certify the dose to the • product.
Placement of Routine dosimeters • Place routine dosimeters at predetermined • routine monitoring position • Place routine dosimeters at least at the beginning, • end of an irradiation lot, in order that it may be • demonstrated that the irradiation process was • under control • The frequency of dosimeter placement should be • sufficient to verify that the process is in control.
For Gamma Irradiator • Dosimeters are typically placed at the • beginning and at the end of each run of a • particular processing category. • Additionally, dosimeters may be placed so at • least one dosimeter is within the irradiator • cell at all times.
For Electron beam irradiator • Dosimeters are typically placed at the • beginning and at the end of each run of a • particular category utilizing a specific set of • processing parameters.
Bulk-flow irradiators • For fluids and grains continuously flow during • irradiation, add several dosimeters to the product • stream at the beginning and during the production • run. • From the statistical distribution of the dose • measurements, the absorbed dose is estimated • with statistical confidence.
Product Processing • Process control • Process interruptions • Dose monitoring • Analysis
Process control • For gamma irradiators, • Record date and time of processing • Set the operating parameters as established during process • qualification • Control and record the dwell time and conveyor speed of • the product
Process control • For Electron Beam irradiators, • Record date and time of processing • Set the operating parameters as established during • process qualification • Measure and record machine variables • beam current • scan width • conveyor speed • Beam energy
Process interruptions • If the parameters deviate outside the • processing limits prescribed from process • qualification, interrupt the process to • evaluate and correct the cause of the • deviations • Effect on the quality of the product
Dose monitoring • The dose measurements at the routine • monitoring position provides a measure of the • process that is independent of any other control • or measurement system of the irradiator. • The minimum frequency of dose measurement • should be chosen based on the particular • requirement of the irradiator or process
Separate location for irradiated product • The identification as irradiated may best be • achieved by ensuring that product is • unloaded from an irradiator to a separate • location from the one which is used for • unirradiated product. This, together with the • use of unique identification labels, ensures a • full trail of traceable records for the product.
Dosimetry • The key quantity that determines the process is • the absorbed dose. • Dosimeters are the devices that are capable of • providing a quantitative and reproducible • measurement of dose. • Various dosimetry techniques are available for • measuring absorbed dose in a quantitative • manner. • Relevant ISO/ASTM standard practices and • guides are available for dosimetry in radiation • processing facilities
Dose Measurement • It has to be demonstrated that • Dose measurement is traceable to a national or • international standard. • The uncertainty of measurement is known. • The Influence of temperature, humidity and • other environmental considerations on • dosimeter response is known and taken into • account
Dosimetry Standards – Measurement • ASTM E2628 “Standard Practice for Dosimetry in Radiation Processing” • ASTM E2701 “Standard Guide for Performance Characterization of Dosimeters and Dosimetry Systems for Use in Radiation Processing” • ISO/ASTM 51261 “Standard Guide for Selection and Calibration of Dosimetry Systems for Radiation Processing” • ISO/ASTM 51707 “Standard Guide for Estimating Uncertainties in Dosimetry for Radiation Processing”
Dosimetry Standards - Application • ISO 11137-3:2006 “Sterilization of health care products – Radiation – Part 3:Guidance on dosimetric aspects” • ASTM E2303 “Standard Guide for Absorbed Dose Mapping in Radiation Processing Facilities” • ISO /ASTM 51608 “Standard Practice for Dosimetry in an X-ray (Bremsstrahlung) Facility for Radiation Processing” • ISO/ASTM 51649 “Standard Practice for Dosimetry in an Electron BeamFacility for Radiation Processing at Energies Between 300 keV and 25MeV” • ISO/ASTM 51702 “Standard Practice for Dosimetry in Gamma Irradiation Facilities for Radiation Processing”
Dosimetry Standards - individual dosimetry system • ISO/ASTM 51205 Practice for Use of a Ceric-Cerous Sulfate Dosimetry System • ISO/ASTM 51275 Practice for Use of a Radiochromic Film Dosimetry System • ISO/ASTM 51276 Practice for Use of a PolymethylmethacrylateDosimetry System • ISO/ASTM 51310 Practice for Use of a Radiochromic Optical Waveguide Dosimetry System • ISO/ASTM 51401 Practice for Use of a Dichromate Dosimetry System • ISO/ASTM 51538 Practice for Use of the Ethanol-ChlorobenzeneDosimetry System
Dosimetry Standards - individual dosimetry system • ISO/ASTM 51540 Practice for Use of a Radiochromic Liquid Dosimetry System • ISO/ASTM 51607 Practice for Use of the Alanine-EPR Dosimetry System • ISO/ASTM 51631 Practice for Use of Calorimetric Dosimetry Systems for Electron Beam Dose Measurements and Dosimeter Calibrations • ISO/ASTM 51650 Practice for Use of Cellulose Acetate Dosimetry Systems • ISO/ASTM 51956 Practice for thermoluminescenceDosimetry (TLD) Systems for Radiation Processing • ASTM E1026 Practice for Using the Fricke Reference Standard Dosimetry System • ASTM E2304 Practice for Use of a LiF Photo-Fluorescent Film Dosimetry System
Dosimetry Standards - any process deviation • ISO/ASTM 51707 Guide for Estimating Uncertainties in Dosimetry for Radiation Processing • ASTM E2232 Guide for Selection and Use of Mathematical Methods for Calculating Absorbed Dose in Radiation Processing Applications
Analysis of the dose measurement • Dosimetric measurements are subject to sizeable uncertainties • Calibration of the dosimetry system • Reproducibility of individual dosimeters • Reproducibility of the positions of dosimeters in dose mapping • experiments, and of the product being irradiated near those • dosimeters; • Stability of the irradiator (beam current, beam energy, • scanning width, conveyor speed for electron beams; variations • in tote properties for gamma irradiators, or in positioning of • product within the totes, for gamma irradiators) • Effects of influence quantities such as temperature, humidity, • dose rate, time between irradiation and measurement the • dosimeters.
For a controlled process • For a process under control, the measured values • of the routine dose will be distributed statistically • about a target dose value. • Use statistical process control techniques to • confirm that the process delivered to the product • meets the conditions established during the • validation exercise.
The irradiated product • The radiation process is mainly governed by the • minimum absorbed dose achieved in the dose • distribution within a given product. • If the required minimum is not applied, the • intended effect may not be achieved. • There are also situations where high dose would • damage the quality of the product
Post irradiation inspection • Inspect if the product suffered any damage as a • result of the process • Irradiation damage (discoloring as a result of a • significant overdose) • Machine damage (tearing of the cartons on the • irradiation conveyor system) • Examine and report routine dosimetry results • If any product cartons suspected of receiving a • non-conforming process are stored in the • segregated area, isolated from the rest of the • product.
Post irradiation inspection • Any cartons identified from the irradiation • records as having had a non-conforming • irradiation (for example, with interruption to the • process) should be held and only released once • investigations have confirmed the process was • under control. • Routine dosimetry obtained along with records of • the machine variable during the irradiation • process are compared with expected and • validated range.
Non Conforming product As a result of • Routine dosimetry measurement indicating the • process was not correct • Evident damage to the carton.
PRODUCT RELEASE Once the product, irradiation process records including routine dosimetry, and other records from the manufacturing process have been approved as conforming to the requirements, the product may be released.
References • Guidelines for the Development, Validation and • Routine Control of Industrial Radiation Process. • IAEA Radiation Technology Series No.4 (2013) • Trends in radiation Sterilization of Health Care • Products. IAEA, STI/PUB/1313 (2008) • ISO 11137:2006 “Sterilization of Healthcare • Products – Radiation” • Part 1: Requirements for development, validation and routine control of a sterilization process for medical devices • Part 2: Establishing the sterilization dose • Part 3: Guidance on dosimetric aspects