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Radiation Protection in Radiotherapy


'The totality of features or characteristics that bear on our ... PAN AMERICAN HEALTH ORGANIZATION, Publicaci n Cientifica No. 499, Control de ... annual: 2 days ... – PowerPoint PPT presentation

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Title: Radiation Protection in Radiotherapy

Radiation Protection in Radiotherapy
IAEA Training Material on Radiation Protection in
  • Part 12
  • Quality Assurance

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.

What is Quality Assurance?
  • All those planned and systematic actions
    necessary to provide confidence that a product or
    service will satisfy given requirements for
  • ISO 9000

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

  • To be familiar with the concepts of Quality
    Assurance as a multidisciplinary activity and its
    interrelation with radiation protection in
  • 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

  • 1. Quality Assurance and the BSS
  • 2. QA systems
  • 3. Quality Control in radiotherapy
  • External Beam RT
  • Brachytherapy
  • 4. QA and radiation protection

1. Quality Assurance and the BSS (Managerial
  • 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.

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

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!
Relevant for radiotherapy
  • WORLD HEALTH ORGANIZATION, Quality Assurance in
    Radiotherapy, WHO, Geneva (1988).
    Cientifica No. 499, Control de Calidad en
    Radioterapia Aspectos Clínicos y Físicos, PAHO,
    Washington, DC (1986).

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

Check machine and data!
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
  • QA applies to both physical and clinical aspects
    of the treatment

BSS appendix II.23
  • Quality assurance programmes for medical
    exposures shall include
  • ...
  • (c) written records of relevant procedures and
  • (d) verification of the appropriate calibration
    and conditions of operation of dosimetry and
    monitoring equipment .

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

Treatment records
  • Must contain all relevant information
  • Can be in electronic format

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

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

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

Good QA systems in radiotherapy
  • Improves work practices
  • Would have prevented most of the major accidents

ISO 9000
  • Comprehensive set of standards for QA (mainly in
    manufacturing and service industry)
  • Adapted e.g. by ESTRO to the radiotherapy
  • 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.

Quick note aside How to get ISO 9000 certified
implementation steps
  • Application
  • Preliminary
  • Pre-audit
  • System audit
  • Certification - registration
  • Surveillance audits

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

A Comprehensive QA Program typically comprises
  • Quality Assurance Committee
  • Policies and Procedures Manual
  • Quality Assurance team
  • Quality audit
  • Resources

QA Committee Membership
  • Must represent the many disciplines within the
  • 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
  • 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

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
  • 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

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
  • For any daily measurement which exceed 4,
    treatment must STOP immediately and the problem
    investigated by the Senior Physicist responsible

Action levels
  • Are quantitative
  • Reflect the required outcome
  • Are informed by the achievable outcome
  • Must be unambiguous
  • Should be easy to understand

QA Committee review
  • Where Action Levels have been exceeded
  • Where set procedures have been discovered to be
  • After a review, recommendations must be
    formulated in writing for improving the QA
  • When errors are discovered the fault often lies
    in the process rather than in the action of

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
  • In short, there is a QA program for the QA

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
Policies and Procedures Manual
  • As a minimum, sections should exist for
  • Administrative procedures
  • Clinical procedures
  • Treatment procedures
  • Physics procedures
  • Radiation safety

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

Quality Assurance Team
  • Includes all disciplines
  • Well defined responsibility and reporting
  • 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

Responsibility Chart
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

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?
Quality Audit
  • Ideally performed by someone outside of the
  • Examples
  • IAEA/WHO TLD program for check of dose in therapy
  • EQUAL program in Europe
  • Audits of clinical trials participation

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

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

And finally QA is not a threat, it is an
  • 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

3. Quality Control in radiotherapy
  • Many documents exist that specify what QC
    activities should be performed in radiotherapy

QC should ensure every step in the treatment
e.g. check source activity
e.g. hand calculation of treatment time
Radiother. Oncol. 1992 gt 50 occasions of data
transfer from one point to another for each
patient! If one of them is wrong - the overall
outcome is affected
QC activities in radiotherapy
  • Three general areas
  • Physical dosimetry
  • Treatment planning (dealt with part 10 lecture 3C
    of the course)
  • Patient treatment

QC activities
  • Must be planned prospectively
  • daily
  • weekly
  • monthly
  • annually
  • whenever needed
  • The following is only a suggestion!

A collection of forms
  • Constantinou C. Protocol and procedures for
    quality assurance of linear accelerators.
    Brockton Constantinou 1994. Available from
    Medical Physics Publishing, Madison.

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
Test of optical components
  • Used for patient set-up
  • Essential
  • Easy to perform
  • Jigs available

RMI test tool
Alignment of lasers for patient set-up
  • Should point to the isocentre
  • Check also line width
  • Check line alignment at least 20cm beyond

Gammex laser and test tool
Quality Control - Weekly
  • Check of source positioning (cobalt 60)
  • Couch movements (lateral, vertical, longitudinal)

Example for weekly QC summary
  • From Constantinou 1992

Quality Control - Monthly
  • Dosimetry
  • Output constancy
  • Backup monitors
  • Central axis DD constancy
  • Flatness/symmetry constancy
  • Timer end effect

Quality Control - Monthly
  • Safety interlocks
  • emergency
  • wedge etc
  • Light/ radiation field coincidence
  • Scales
  • Isocentre position
  • Cross hair position

Quality Control - Monthly
  • Field size indicators
  • Distance measuring indicators
  • Jaw symmetry
  • Latching of wedges, trays etc.
  • Wedge position (factors etc.)

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.

How to decide on frequency for tests?
  • Likelihood of failure
  • Severity of the consequences if something goes
  • Ease of the test - resources required
  • This depends on local circumstances!!!

Time requirements for QC
  • External beam per megavoltage unit
  • daily 30 minutes
  • weekly 2 hours
  • monthly gt 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
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

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

QC for Brachytherapy Sources- multiple seeds
  • Suggested calibration tolerances
  • Ideal
  • mean of batch (3)
  • Deviation from mean (5)
  • Practical
  • Review manufacturers documentation for
  • Review ALL the manufacturers documentation

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

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

QC for Remote Afterloading
  • Annual
  • Dose calculation algorithm
  • Simulate emergency conditions
  • Verify source inventory

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

Examples for forms
Forms are useful for all tests
Simple ticks may be sufficient
Empty space for comments and drawings
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
  • Requires a qualified expert
  • Action levels should be set

A note on action levels
  • Not too tight - one must be realistic about what
    can be achieved
  • Not too lax - one must identify unsatisfactory
  • As the practice improves, the action levels may
    be tightened

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

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
QC for Dosimetry Equipment
  • Local standard
  • 2 yearly calibration
  • Field instruments
  • yearly calibration
  • Linearity
  • Leakage
  • Recombination

QC for Measuring Equipment
  • Automated scanners
  • Positional accuracy
  • Alignment
  • Accuracy of data analysis
  • Accessories
  • Thermometer
  • Barometer

Clinical QC
  • Not only physics and dosimetry must be subject to
    QC, also clinical management
  • A good way to do this are chart rounds

Chart Rounds
  • Regular review of patients
  • Can be all patients or randomly selected patients
  • Should include all patients with unexpected
    severe complications

Treatment Verification - do not check individual
links in the chain but verify the overall outcome
Treatment verification
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

Example for verification WHO/IAEA photon dose
TLD capsules
Level 1 Intercomparison Dose in Reference
Treatment verification
  • May be suitable for external audits
  • Should verify localization of the radiation beam
    AND the dose delivered
  • Could include in vivo dosimetry

4. QA and radiation protection
  • Quality assurance is essential for a functioning
    system of radiation protection
  • The BSS identifies the following areas in
  • Requirements for Practices
  • Safety of Sources
  • Medical Exposure
  • Occupational Exposures

QA in medical exposures
  • Physical QA as discussed before
  • Process QA

QA Program Arrangements to be required from the
  • 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

Also the radiation protection program itself
requires QA
  • Check that the program meets its objectives
  • Document improvements
  • Document and rectify deficiencies
  • Raise awareness

The cost of QA
  • Dedicated staff - qualifications, training and
  • Equipment - include allowance for redundancy
  • Time - commissioning, QA, reports, meetings,

What do we get?
Yes, correct - lots of documentation. But there
are other benefits...
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

Additional benefits
  • Credibility
  • Potential to attract funding (and account for
  • Participation in multicenter clinical trials
  • Regular updates and audits to continue the
  • Pride and confidence of staff

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

But - Beware the Administration Tick in the Box
  • 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...

What do we risk without a Quality Assurance
  • 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

What do we risk without a Quality Assurance
  • 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!

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
  • 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. 241558-98 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.
    Cientifica No. 499, Control de Calidad en
    Radioterapia Aspectos Clínicos y Físicos, PAHO,
    Washington, DC (1986).

WHO (World Health Organisation). Quality
Assurance in radiotherapy. Geneva 1988.
  • Quality Assurance is an essential part of
  • 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
  • QA is a continuous process - it is aimed at
    achieving improvements not laying blame.

Any questions?
  • Please give an example for the concept of
    Continuous Quality Improvement from your practice.

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

  • Lee Collins, Westmead Hospital, Sydney
  • Lyn Oliver, Royal North Shore Hospital, Sydney
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