ASSESSMENT OF OCCUPATIONAL EXPOSURE DUE TO INTAKES OF RADIONUCLIDES

1. ASSESSMENT OF OCCUPATIONAL EXPOSURE DUE TO INTAKES OF RADIONUCLIDES Quality Assurance and Quality Control

2. Quality Assurance and Quality Control – Unit Objectives The objectives of this unit is to outline the principles of quality assurance, quality control and quality assessment as they relate to the internal dose assessment programme, and to stress the importance of effective quality assurance to internal dosimetry. At the completion of this unit, the student should understand the basic concepts of quality assurance, and how to apply them in the workplace.

3. Quality Assurance and Quality Control – Unit Outline • Quality Assurance • Quality Control • Operational Considerations • Quality Assessment

4. Quality Assurance

5. The BSS require, inter alia, the establishment and implementation of quality assurance programmes to ensure that protection and safety requirements are met. Requirement for Quality Assurance

6. Quality System includes several elements • Appropriate management support. • Development, implementation and management of QA/QC system. • Clear documentation of quality methods, procedures and test results. • Quality awareness and training of personnel. • Proof or certification of QA from equipment suppliers.

7. Quality System includes several elements • Acceptance and testing of new materials. • Appropriate maintenance and testing of equipment, materials and processes. • Calibration, and verification of the calibration facilities. • Reliable testing of the system performance. • Periodic performance testing of the system.

8. Quality Assurance - planned and systematic actions necessary to provide adequate confidence that a dosimetry product or service will satisfy given requirements for quality. • Examples of QA: • type testing, performance testing, and quality audits required by a regulatory body. • blind testing and quality audits of the dosimetry service provider performed by the user of the service. Quality Assurance

9. Technical specifications may not in themselves guarantee that a customer's requirements will be consistently met, if there happen to be any deficiencies in the specifications or in the organizational system to design and produce the service. Why Quality Assurance?

10. What is Quality? • A high standard or level. • Degree of excellence. • Distinguishing feature. • Faculty, skill, accomplishment. • Satisfaction of a customer’s needs or requirements. Quality is “totality of characteristics of an entity that bear on its ability to satisfy stated and implied needs”.

11. Quality assurance requirements • Registrants and licensees should be responsible for establishing the quality assurance programme required by the principal requirements of the applicable standards. • The quality assurance programme should be designed in relation to the magnitude and the likelihood of potential workplace exposures.

12. QA programme should be consistent with; • Number of workers monitored • Magnitude and likelihood of exposures • Number of individuals monitored • Type of monitoring provided • Direct measurements • Indirect measurements • Choice of monitoring periods

13. ISO 9000 Series of Quality Assurance standards • First published in 1987. • Brought international harmonization. • Supported quality as a factor of international trade. • Embodies comprehensive quality management concepts and guidance.

14. ISO/IEC 17025 GENERAL REQUIREMENTS FOR THE COMPETENCE OF TESTING AND CALIBRATION LABORATORIES

15. A complete QA program needs: • Compliance with operational requirements stated in accepted written criteria, • Clear and complete documentation of the in-house QA program, • Periodic performance evaluations, • Documented procedures and Q.A. program for services provided to customers, • Adequate training program for the staff.

16. A Quality Assurance programme should provide for: Planned and systematic actions to provide adequate confidence that requirements for monitoring occupational exposure are satisfied, including provisions for feedback of operational experience;

17. A Quality Assurance programme should provide for: A framework for the structuring and analysis of tasks, development of methods, establishment of norms and identification of necessary skills for the execution of the monitoring program; and

18. A Quality Assurance programme should provide for: Validation of designs, manufacturing and supply of equipment and materials, as well as operating, maintenance, inspection and testing procedures.

19. Quality Control

20. Quality Control • Quality Control - The operational techniques and activities that are used to fulfil requirements for quality. • Examples of QC: • routine (i.e. daily) use of irradiated control dosimeters, • various statistical analyses used to verify continued system performance.

21. Quality Control demands, • Procedures and protocols for proper management of the dosimetry program. • Dosimetry system calibration. • Routine verification of proper instrument performance. • Detailed documentation of all measurement, evaluation and reporting procedures. • Data recording and archiving.

22. Quality Control procedures • Should be carried out at appropriate intervals • Should cover the following: • Documentation of the required performance criteria • Identification of the person responsible for operation and maintenance of equipment • Use of traceable radionuclide reference standards • Performance checks of measurement systems

23. Quality Control procedures • Quality Control procedures should also cover: • Instrument calibration, • Participation in interlaboratory-comparison programs, • Computational checks, • Periodic review of procedures, specifications and operating records, • Observation of operations and evaluation of quality control data,

24. Quality Control procedures • Finally, Q.C. procedures should cover: • Evaluation of compliance with the performance criteria of appropriate standards • Evaluation of quality control data to ensure the long‑term consistency of analytical results • Verification of determinations of minimum detectable activities

25. Documentation of methods, procedures and test results • Methods used and procedures set up to control the various processes within the service, should be well documented. • This is important for inspection of the service by official authorities as part of an approval system.

26. Documentation of methods, procedures and test results • Quality Handbook • covers all aspects of the quality system in a concise and practical way. • uses other documents as references as needed. • Appropriate parts of the documentation should be made available to staff members • It may even be useful to display operational instructions "on the spot".

27. Dosimetry staff needs to be properly trained • Basic philosophy and strategy of individual monitoring. • Principles and methods used. • Detailed procedures. • Technicalities and potential problems of the processes.

28. Training is a basic QA requirement • Training is essential for direct and indirect measurement staff • Personnel responsible for: • operation • calibration • interpretation of data, and • equipment maintenance

29. Staff training should include: • Basic philosophy and strategy of internal dose assessment • Principles and details of the methods used • Technical details and potential problems of the processes in which they are involved • Recognition and reporting of problems that arise

30. Staff training should include: • Relationship of their work with other parts of the process • Trouble shooting • Knowledge of the overall quality system and its objectives • Their particular responsibility within the quality system

31. Various sources of training are available • Training can be provided through • On-the-job training • Formal classroom sessions • Technologist certification programs • Participation in intercomparison programmes • International fellowship programmes

32. Operational Considerations

33. QA for indirect measurements includes: • Unique labelling which identifies the sample and the person concerned throughout the process from sampling to the recording of the measurement results • Chain of custody of all samples to preclude loss, contamination, tampering or incorrect analysis • Empty and full sample containers should be sealed and transfer of containers should be documented at each stage of the operation

34. QA for indirect measurements includes: • Quality requirements for the acquisition of all chemicals, equipment and other materials used in monitoring • Regularly scheduled calibration of all chemical procedures and detection systems, and frequent background monitoring • Calibration and background measurements should typically represent 10% or more of all measurements performed by each method of analysis

35. Direct measurement issues • Assurance that a direct measurement program achieves the required level of quality requires attention to practical operational issues • Two practical issues should be addressed: • Control of contamination and other extraneous sources of radiation, and • Reproducible subject positioning.

36. Subject positioning • Procedures should specify measurement reference points used for subject positioning for each type of measurement • It is necessary to maintain the validity of the calibrations and the reproducibility of subsequent measurements for biokinetics • Required repositioning accuracy depends on the measurement objectives, and, to some degree, the geometry used for measurement

37. Subject positioning • For example, when counting 238Pu in the lungs with a phoswich detector, variations in detector placement of 1 cm from the optimum position can result in changes of 10-20 percent in the 17-keV peak count rate • Repositioning sensitivity is much less severe for radionuclides that emit higher energy photons and are distributed through the body

38. Subject positioning • Select anatomical references that are unambiguous and identified with the degree of accuracy necessary for the measurement • For example, when performing lung counting, the notch at the top of the sternum can be detected quite easily with light pressure of the finger and is a commonly used reference • Other easily identifiable and reproducible body references can be used

39. Subject positioning • When whole-body measurements are made with a bed geometry system, the top of the head, or bottom of the feet are references that offer adequate accuracy • The important points are reproducibility and clear specification of the references.

40. Contamination control • Contamination and extraneous radiation sources must be prevented from entering counter or counting room • Equipment and supplies entering the counting room or detector area should be minimized • Items necessary for facility operation should be monitored with counting equipment before entering the shielded portion of the facility

41. Contamination control • Particular attention should be given to external contamination or extraneous radiation sources carried by the individuals to be counted • Individuals should remove watches and jewelry that could have radioactive gemstones • Clothing or skin of individuals can be contaminated and should be monitored • Hair is often a particular site for contamination

42. Contamination control • It may be necessary to provide clothing change or even shower facilities for use prior to measurement • It may be practical to take such steps routinely to avoid the additional effort to check for external contamination • Routine use of shoe covers is often prudent • They can either be reusable or disposable.

43. Internal contamination • Internal contamination not related to the measurement objective can be a concern • On occasion, individuals who are to be measured for radiation protection purposes may have had recent administration of radiopharmaceuticals for medical purposes • It is good practice to confirm that such medical procedures have not been performed in a time frame that could cause problems

44. Internal contamination • Radon and thoron daughter products are inadvertent sources of internal contamination • These can result in elevated radionuclide levels of individuals who work or live in locations where high levels are natural • Levels of radioactivity decrease fairly rapidly when the individual leaves the high level area • However, retained internal contamination can cause interferences that can be misinterpreted

45. QA of the sources or phantoms • Validation of the amount of radioactivity – sources and source materials should be traceable to a national standard • Establish the uniformity of the radioactive material distribution in whole body or organ phantoms • Verify that those physical dimensions important to the determination of the radiation transmission and emission from the source or phantom are proper

46. Quality Assessment

47. Quality Assessment includes: • Accreditation • Audits • Intercomparisons

48. Accreditation – Independent assessment • It is important to establish independent methods to assess the quality of internal dosimetry programmes • Accreditation is a formal recognition that an organization is competent to carry out specific activities • National programs are being developed to address internal dosimetry • Accreditation is conducted through on-site audits, as well as use of standardized sources, samples and phantoms for comparison

49. Accreditation – Independent assessment Accreditation programmes address the full range of laboratory quality assurance components, including; • Procedures • Documentation • Training • Calibration • Maintenance • Corrective actions, and • Measurement accuracy and precision

50. Audits • The objective of audits is to enhance the effectiveness and efficiency of the internal dosimetry programme • Audits should be conducted by: • People who are technically competent, but • Do not have any direct responsibility for those activities