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12. Medical exposure: Quality assurance (2,359 KB)



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  • 1. Radiation Protection in Radiotherapy Part 12 Quality Assurance IAEA Training Material on Radiation Protection in Radiotherapy
  • 2. QUALITY as a goal
    • “ The totality of features or characteristics that bear on our ability to satisfy the stated or implied goal of effective patient care.”
    • Comprehensive QA for Radiation Oncology,
    • AAPM Task Group 40, 1994
    • To ensure the goal is reached requires a fully implemented Quality Assurance program throughout the facility.
  • 3. What is Quality Assurance?
    • “ All those planned and systematic actions necessary to provide confidence that a product or service will satisfy given requirements for quality.”
    • ISO 9000
  • 4. Quality Assurance
    • In the BSS seen in the context of medical exposure as essential for radiation protection of the patient
    • Quality Assurance and Control is also important to assess the overall effectiveness of protection and safety measures
  • 5. Objectives
    • To be familiar with the concepts of Quality Assurance as a multidisciplinary activity and its interrelation with radiation protection in radiotherapy.
    • To be familiar with Quality Assurance procedures as a tool for reviewing and assessing the overall effectiveness of a radiation protection program.
    • To be able to understand the need for and role of specific tests in the context of Quality Control and be able to identify appropriate national and international protocols for this task
    • To be aware of the need for involvement of professionals in a Quality Assurance program and for radiation protection
  • 6. Contents
    • 1. Quality Assurance and the BSS
    • 2. QA systems
    • 3. Quality Control in radiotherapy
      • External Beam RT
      • Brachytherapy
    • 4. QA and radiation protection
  • 7. 1. Quality Assurance and the BSS (Managerial Requirements)
    • BSS 2.29. “Quality assurance programmes shall be established that provide, as appropriate:
      • (a) adequate assurance that the specified requirements relating to protection and safety are satisfied; and
      • (b) quality control mechanisms and procedures for reviewing and assessing the overall effectiveness of protection and safety measures. ”
  • 8. QA and QC
    • Quality Assurance is the overall process which is supported by Quality Control activities
    • Quality Control describes the actual mechanisms and procedures by which one can assure quality
  • 9. Quality Assurance and Medical Exposure
    • BSS appendix II.22. “Registrants and licensees, in addition to applying the relevant requirements for quality assurance specified elsewhere in the Standards, shall establish a comprehensive quality assurance programme for medical exposures with the participation of appropriate qualified experts in the relevant fields, such as radiophysics or radiopharmacy, taking into account the principles established by the WHO and the PAHO.”
    You must establish a QA program!
  • 10. Relevant for radiotherapy
    • WORLD HEALTH ORGANIZATION, Quality Assurance in Radiotherapy, WHO, Geneva (1988).
    • PAN AMERICAN HEALTH ORGANIZATION, Publicación Cientifica No. 499, Control de Calidad en Radioterapia: Aspectos Clínicos y Físicos , PAHO, Washington, DC (1986).
  • 11. BSS appendix II.23
    • “ Quality assurance programmes for medical exposures shall include:
      • (a) measurements of the physical parameters of the radiation generators, imaging devices and irradiation installations at the time of commissioning and periodically thereafter;
      • (b) verification of the appropriate physical and clinical factors used in patient diagnosis or treatment; …”
    Check machine and data!
  • 12. Consequences for radiotherapy
    • A good acceptance testing and commissioning program is fundamental for any QA activities
    • QA activities are typically a subset of the tests and procedures used for the commissioning of a unit
    • QA applies to both physical and clinical aspects of the treatment
  • 13. BSS appendix II.23
    • “Quality assurance programmes for medical exposures shall include:
      • ...
      • (c) written records of relevant procedures and results;
      • (d) verification of the appropriate calibration and conditions of operation of dosimetry and monitoring equipment; .…”
  • 14. Consequences for radiotherapy
    • Treatment records must be kept of all relevant aspects of the treatment - including
      • Session and Summary Record information
      • Records all treatment parameters
      • Dose Calculations
      • Dose Measurements
    • Particular emphasis is placed on QA of dosimetry
  • 15. Treatment records
    • Must contain all relevant information
    • Can be in electronic format
  • 16. BSS appendix II.23
    • “Quality assurance programmes for medical exposures shall include:
      • ...
      • and
      • (e) as far as possible, regular and independent quality audit reviews of the quality assurance programme for radiotherapy procedures”
  • 17. Consequences for radiotherapy
    • A QA system itself and its outcomes must be critically reviewed
    • External audits are recommended to verify that the checks are not only done but that they also achieve what they are supposed to do
    • Every good system requires an independent look at times
  • 18. 2. QA systems
    • Many QA systems exist - one important example is the ISO 9000 system
    • They are highly successful in manufacturing industry because they do improve productivity and avoid costly mistakes
  • 19. Good QA systems in radiotherapy
    • Improves work practices
    • Would have prevented most of the major accidents
  • 20. ISO 9000
    • Comprehensive set of standards for QA (mainly in manufacturing and service industry)
    • Adapted e.g. by ESTRO to the radiotherapy environment
        • European Society for Therapeutic Radiology and Oncology (ESTRO) Advisory Report to the Commission of the European Union for the 'Europe Against Cancer Programme'. Quality Assurance in radiotherapy. Radiother. Oncol. 35: 61-73; 1995.
  • 21. Quick note aside: How to get ISO 9000 certified… implementation steps
    • Application
    • Preliminary
    • Pre-audit
    • System audit
    • Certification - registration
    • Surveillance audits
  • 22. A Comprehensive Quality Assurance Program
    • The details of such a program are often wrapped up in a “Code of Practice”.
      • “ Quality Assurance in Radiotherapy”, ESTRO Advisory Report, 1995
      • “ Comprehensive QA for Radiation Oncology: Report of AAPM Radiation Therapy Committee Task Group 40”, 1994
      • “ Quality Assurance in Radiotherapy”, WHO, 1988
  • 23. A Comprehensive QA Program typically comprises
    • Quality Assurance Committee
    • Policies and Procedures Manual
    • Quality Assurance team
    • Quality audit
    • Resources
  • 24. QA Committee Membership
    • Must represent the many disciplines within the department
    • Should be chaired by the Head of Department
    • As a minimum must include a medical doctor, a physicist, a radiotherapy technologist and an engineer responsible for service and maintenance
    • Must be appointed and supported by senior management
    • Must have sufficient depth of experience to understand the implications of the process
    • Must have the authority and access to the resources to instigate and carry out the QA process
  • 25. Quality Assurance Committee
    • Should ‘represent’ the department
    • Should be ‘visible’ AND accessible to staff
    • Oversees the entire Quality Assurance program
    • Writes policies to ensure the quality of patient care
    • Assists staff in tailoring the program to meet the needs of the Department (using published reports as a guide)
    • Monitor and audit the program to ensure that each component is being performed and documented
  • 26. Quality Assurance Committee
    • Set agreed “Action Levels”
    • Example: Physics is given the authority to ensure correct accelerator output
    • For the daily output check two “Action Levels” are set
      • For any daily measurement which exceeds 2% but less than 4%, treatment may continue but the Senior Physicist responsible must be notified (immediately)
      • For any daily measurement which exceed 4%, treatment must STOP immediately and the problem investigated by the Senior Physicist responsible
  • 27. Action levels
    • Are quantitative
    • Reflect the required outcome
    • Are informed by the achievable outcome
    • Must be unambiguous
    • Should be easy to understand
  • 28. QA Committee review
    • Where “Action Levels” have been exceeded
    • Where set procedures have been discovered to be faulty
    • After a review, recommendations must be formulated in writing for improving the QA program
    • When errors are discovered the fault often lies in the process rather than in the action of individuals
  • 29. Documentation for the Quality Assurance Committee
    • Terms of Reference
    • The Committee must meet at established intervals and retain for audit purposes the minutes of its meetings, actions recommended and the results attained.
    • In short, there is a QA program for the QA Committee
  • 30. Policies and Procedures Manual
    • This manual contains clear and concise statements of all the policies and procedures carried out in the Department
    • Reviewed (typically) yearly
    • Updated as procedures change
    Policies and Procedures Manual
  • 31. Policies and Procedures Manual
    • As a minimum, sections should exist for
      • Administrative procedures
      • Clinical procedures
      • Treatment procedures
      • Physics procedures
      • Radiation safety
  • 32. Policies and Procedures Manual
    • It must be “signed off” by the Head of Department and appropriate section heads
    • It is important that all staff have “ownership” to the manual - it should reflect the opinions of all and be agreed to by all
    • A list of all copies of the Manual and their locations must be kept to ensure that each copy is updated
  • 33. Quality Assurance Team
    • Includes all disciplines
    • Well defined responsibility and reporting structure
    • Each member of the team must
      • Know his/her responsibility
      • Be trained to perform them
      • Know what actions are to be taken should a test or action be outside the preset “action levels”
  • 34. Responsibility Chart Leer Area Professional
  • 35. Quality Assurance Team
    • Each member of the team must also
      • Have at least some understanding of the consequences when tests or actions are outside the “action levels”
      • Maintain records documenting the frequency of performance, the results and the corrective action taken if necessary
  • 36. Quality Audit
    • “ A systematic and independent examination and evaluation to determine whether quality activities and results comply with planned arrangements and whether the arrangements are implemented effectively and are suitable to achieve the objectives.”
    • “ Quality assurance in radiotherapy.”, Radiother. Oncol., 1995
    Do you do what you say you do?
  • 37. Quality Audit
    • Ideally performed by someone outside of the organisation
    • Examples
      • IAEA/WHO TLD program for check of dose in therapy units
      • EQUAL program in Europe
      • Audits of clinical trials participation
  • 38. Quality Assurance does not stop here! The Quality Assurance Committee and the Quality Assurance team must continuously monitor new information and implement this in their procedures
  • 39. Continuous Quality Improvement
    • CQI - many other acronyms are available for this
    • Part of virtually all QA systems
    • Improved methods on cancer patient management are documented in clinical trial reports.
    • Quality assurance protocols are continuously under development in many countries
    • Regular Quality Assurance meeting for all members of a Section
    • Continuing education - lectures, workshops, journal clubs and must be available for all staff
  • 40. And finally: QA is not a threat, it is an opportunity
    • It is essential in a QA program that all staff feel free to report errors
    • A non threatening environment must exist
    • Reward honesty with encouragement
    • Education is the key, not punishment
  • 41. 3. Quality Control in radiotherapy
    • Many documents exist that specify what QC activities should be performed in radiotherapy…
  • 42. QC should ensure every step in the treatment chain... e.g. : check source activity e.g. : hand calculation of treatment time
  • 43. Radiother. Oncol. 1992: > 50 occasions of data transfer from one point to another for each patient! If one of them is wrong - the overall outcome is affected
  • 44. QC activities in radiotherapy
    • Three general areas:
      • Physical dosimetry
      • Treatment planning (dealt with part 10 lecture 3C of the course)
      • Patient treatment
  • 45. QC activities
    • Must be planned prospectively
      • daily
      • weekly
      • monthly
      • annually
      • whenever needed…
    • The following is only a suggestion!
  • 46. A collection of forms
    • Constantinou C.: Protocol and procedures for quality assurance of linear accelerators. Brockton: Constantinou; 1994. Available from Medical Physics Publishing, Madison.
  • 47. External Beam Radiotherapy Examples for daily QC
    • Safety
      • door and other interlocks
      • radiation warning lights
      • audiovisual
      • radiation area monitor
    • Radiation constancy check
    • Mechanical/optical “pointers”
    PTW Linacheck
  • 48. Test of optical components
    • Used for patient set-up
    • Essential
    • Easy to perform
    • Jigs available
    RMI test tool
  • 49. Alignment of lasers for patient set-up
    • Should point to the isocentre
    • Check also line width
    • Check line alignment at least 20cm beyond isocentre
    Gammex laser and test tool
  • 50. Quality Control - Weekly
    • Check of source positioning (cobalt 60)
    • Couch movements (lateral, vertical, longitudinal)
  • 51. Example for weekly QC summary
    • From Constantinou 1992
  • 52. Quality Control - Monthly
    • Dosimetry
      • Output constancy
      • Backup monitors
      • Central axis %DD constancy
      • Flatness/symmetry constancy
      • Timer end effect
  • 53. Quality Control - Monthly
    • Safety interlocks
      • emergency
      • wedge etc
    • Light/ radiation field coincidence
    • Scales
    • Isocentre position
    • Cross hair position
  • 54. Quality Control - Monthly
    • Field size indicators
    • Distance measuring indicators
    • Jaw symmetry
    • Latching of wedges, trays etc.
    • Wedge position (factors etc.)
  • 55. Quality Control - Annual
    • Dosimetry
    • Safety
    • Mechanical These checks are a scaled down version of the commissioning checks. It is a major QC exercise and is intended to validate the unit for another twelve months.
  • 56. How to decide on frequency for tests?
    • Likelihood of failure
    • Severity of the consequences if something goes wrong
    • Ease of the test - resources required
    • This depends on local circumstances!!!
  • 57. Time requirements for QC
    • External beam per megavoltage unit
      • daily: 30 minutes
      • weekly: 2 hours
      • monthly: > 4 hours
      • annual: 2 days +
    • These are estimates only - a qualified expert must decide on the actual requirements for a particular treatment unit
    Siemens Primus Linac
  • 58. QC for Brachytherapy Sources
    • The following QC should be done on receipt of the sources and documented
      • Physical/chemical form
      • Source encapsulation
      • Radionuclide distribution and uniformity
        • Autoradiograph
        • Uniformity of activity amongst seeds
        • Visual inspection of seeds in ribbons
  • 59. QC for Brachytherapy Sources
    • Calibration
      • Do on receipt and document
      • Ideal - every source
      • Long half-life sources ( e.g. Cs 137)
        • All
      • Short half-life sources ( e.g. I 125)
        • If only a few, do them all
        • If a large number, do a sample e.g. 10%
  • 60. QC for Brachytherapy Sources- multiple seeds
    • Suggested calibration tolerances
      • Ideal
        • mean of batch (3%)
        • Deviation from mean (5%)
      • Practical
        • Review manufacturer’s documentation for tolerances
    • Review ALL the manufacturer’s documentation
  • 61. QC for Remote Afterloading
    • Before each treatment day
      • Room safety door interlocks
      • Lights and alarms
      • Radiation monitor
      • Console functions
      • Visual inspection of source guides
      • Verify accuracy of ribbon preparation
  • 62. QC for Remote Afterloading
    • Weekly
      • Accuracy of source and dummy loading
      • Source positioning
    • At each source change or quarterly
      • Calibration
      • Timer function
      • Accuracy of source guides and connectors
  • 63. QC for Remote Afterloading
    • Annual
      • Dose calculation algorithm
      • Simulate emergency conditions
      • Verify source inventory
  • 64. QC Documentation
    • Forms shall be established to guide the process
      • easy to follow (even late in the evening after normal treatment has finished)
      • diagrams useful
  • 65. Examples for forms
  • 66. Forms are useful for all tests Simple ticks may be sufficient Empty space for comments and drawings
  • 67. Special equipment and procedures
    • All equipment and all procedures should be tested
    • To design a QC protocol, one needs to fully understand the goals and all steps of the procedure
    • Requires a qualified expert
    • Action levels should be set
  • 68. A note on action levels
    • Not too tight - one must be realistic about what can be achieved
    • Not too lax - one must identify unsatisfactory practice
    • As the practice improves, the action levels may be tightened
  • 69. Not only treatment units require QC: Simulator
    • Appropriate sections from the QC activities for a treatment unit
    • kVp and mAs calibration
    • Image intensifier quality checks
    • Automatic exposure control if applicable
    • Film processor
  • 70. CT scanner
    • Image quality
    • Scaling and deformation
    • Transfer of data
    • Transfer of patient (is positioning OK, is couch on CT and linac identical?)
    Gammex RMI CT test tool
  • 71. QC for Dosimetry Equipment
    • Local standard
      • 2 yearly calibration
    • Field instruments
      • yearly calibration
    • Linearity
    • Leakage
    • Recombination
  • 72. QC for Measuring Equipment
    • Automated scanners
      • Positional accuracy
      • Alignment
      • Accuracy of data analysis
    • Accessories
      • Thermometer
      • Barometer
  • 73. Clinical QC
    • Not only physics and dosimetry must be subject to QC, also clinical management
    • A good way to do this are ‘chart rounds’
  • 74. Chart Rounds
    • Regular review of patients
    • Can be all patients or randomly selected patients
    • Should include all patients with unexpected severe complications
  • 75. Treatment Verification - do not check individual links in the chain but verify the overall outcome Treatment verification
  • 76. Treatment Verification
    • Checks large parts of the treatment chain at once – one detects if something is wrong but not necessarily what the problem is.
    • Good strategy when things are mostly OK and within tight tolerances
    • Allows to follow complex processes
  • 77. Example for verification: WHO/IAEA photon dose intercomparison TLD capsules Level 1 Intercomparison: Dose in Reference Conditions
  • 78. Treatment verification
    • May be suitable for external audits
    • Should verify localization of the radiation beam AND the dose delivered
    • Could include in vivo dosimetry
  • 79. 4. QA and radiation protection
    • Quality assurance is essential for a functioning system of radiation protection
    • The BSS identifies the following areas in particular:
      • Requirements for Practices
      • Safety of Sources
      • Medical Exposure
      • Occupational Exposures
  • 80. QA in medical exposures
    • Physical QA as discussed before
    • Process QA
  • 81. QA Program: Arrangements to be required from the licensee
    • Procedures to establish patient identity
    • Procedures to ensure accordance with prescription by a medical practitioner
    • Procedures to ensure that radiation sources, including equipment can only be purchased from manufacturers and distributors authorized by the Regulatory Authority
  • 82. Also the radiation protection program itself requires QA
    • Check that the program meets its objectives
    • Document improvements
    • Document and rectify deficiencies
    • Raise awareness
  • 83. The cost of QA
    • Dedicated staff - qualifications, training and numbers
    • Equipment - include allowance for redundancy
    • Time - commissioning, QA, reports, meetings, training
  • 84. What do we get? Yes, correct - lots of documentation. But there are other benefits...
  • 85. The benefits of QA
    • Benefits for the department
      • improved management system
      • improved communication
      • improved safety
      • less duplication and waste
    • Benefits to patients
      • optimized procedure
      • re-assurance
  • 86. Additional benefits
    • Credibility
    • Potential to attract funding (and account for it…)
    • Participation in multicenter clinical trials
    • Regular updates and audits to continue the improvements
    • Pride and confidence of staff
  • 87. Involvement of Administration
    • Without the support of the Administration the financial resources will not be made available
    • The AAPM considers this to be so important that in their Quality Assurance policy they make the very first section “Part A: Information for Radiation Oncology Administrators”.
    • “ Educate those who control funding”
    • Comprehensive QA for Radiation Oncology, Task Group 40, 1994
  • 88. But - Beware the Administration “Tick in the Box” syndrome!
    • Administration will agree with QA
    • They may even insist upon it
    • Without education they will not understand what that really means in our environment
    • Most administrators equate QA with an “audit”
    • Many simply require the right boxes get ticked so they can be seen to do have done their job - this is not enough...
  • 89. What do we risk without a Quality Assurance Program?
    • Exeter, UK
      • New cobalt 60 source installed
      • Over the next 5 months, 207 patients were overdosed by 25% due to an incorrect calibration
    • Contributing factors
      • Calibration details not recorded
      • Little documentation or protocols
  • 90. What do we risk without a Quality Assurance Program?
    • Exeter: Contributing factors (cont.)
      • Reduced staffing levels (money)
      • No independent check of calculations
      • No independent check calibration
    • It was detected during a Nation wide survey!
  • 91. Where to get more information
    • AAPM task group 40: Kutcher GJ, Coia L, Gillin M, Hanson W, Leibel S, Morton RJ, Palta J, Purdy J, Reinstein L, Svensson G, et al. Comprehensive QA for radiation oncology: report of AAPM therapy committee task group 40. Med Phys 1994;21:581-618.
    • AAPM task group 53: Fraas, B. et al. Quality assurance for clinical radiotherapy treatment planning. Med. Phys. 25: 1773-1829; 1997.
    • AAPM task group 56: Nath R.; Anderson L.; Meli J.; Olch A.; Stitt J. A.; Williamson J. Code of practice for brachytherapy physics: report of the AAPM Radiation Therapy Committee Task Group No 56. Med. Phys. 24:1558-98; 1997.
    • ACPSEM Position Paper: Millar M, Cramb J, Das R, Ackerly T, Brown G, Webb D. ACPSEM Position Paper: Recommendations for the safe use of external beams and sealed brachytherapy sources in radiation oncology. Aust.Phys.Eng.Sci.Med. 1997; 20 (Supp): 1-35
    • Institute of Physical Sciences in Medicine. Commissioning and quality assurance of linear accelerators, IPSM report 54. York: IPSM; 1988.
    • International Standards Organisation. Quality management and quality assurance standards. ISO 9000 series.
    • PAN AMERICAN HEALTH ORGANIZATION, Publicación Cientifica No. 499, Control de Calidad en Radioterapia: Aspectos Clínicos y Físicos, PAHO, Washington, DC (1986).
  • 92. WHO (World Health Organisation). Quality Assurance in radiotherapy. Geneva 1988.
  • 93. Summary
    • Quality Assurance is an essential part of radiotherapy
    • It affects all aspects including the radiation protection program
    • There are many different standards and guidelines for specific QA activities - it requires a qualified expert to choose the most appropriate for a particular center
    • QA requires and encourages regular external audits
    • QA is a continuous process - it is aimed at achieving improvements not laying blame.
  • 94. Any questions?
  • 95. Question Please give an example for the concept of Continuous Quality Improvement from your practice.
  • 96. Example… just one of many
    • A centre intends to improve treatment set-up. The measure patient positioning using port films on 20 patients e.g. of the prostate. The random variations are of the order of 8mm and the systematic error on average 9mm.
    • The systematic error could at least partially attributed to different couch sag in simulator and treatment unit. This is reflected in update of the procedures.
    • A repeat test shows that not only the systematic but also the random uncertainty have improved (the latter potentially because of heightened awareness). The smaller random variation allows to pick up other systematic errors…
    • In addition to this the positive experience leads to the same tests to be done for other treatment sites...
  • 97. Acknowledgment
    • Lee Collins, Westmead Hospital, Sydney
    • Lyn Oliver, Royal North Shore Hospital, Sydney