Radiation Protection Radiation Protection in in Radiotherapy Radiotherapy Part 12 Part 12 Quality Assurance Quality Assurance IAEA Training Material on Radiation Protection in Radiotherapy
Transcript
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, Publicacin Cientifica No.
499, Control de Calidad en Radioterapia: Aspectos Clnicos y Fsicos
, 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
PTW
54. Quality Control - Monthly
Field size indicators
Distance measuring indicators
Jaw symmetry
Latching of wedges, trays etc.
Wedge position (factors etc.)
RMI
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
Mentor
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%
Nucletron
60. QC for Brachytherapy Sources- multiple seeds
Suggested calibration tolerances
Ideal
mean of batch (3%)
Deviation from mean (5%)
Practical
Review manufacturers documentation for tolerances
Review ALL the manufacturers 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
Gammasonics
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
PTW
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
Leer
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, Publicacin Cientifica No.
499, Control de Calidad en Radioterapia: Aspectos Clnicos y Fsicos,
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...