Transcript 01 IAEA, BSS and DRLs Uganda 2013

IAEA, the BSS and DRLs
Regional Meeting on the Establishment and Utilization of Diagnostic Reference Levels
Kampala, Uganda, 14-18 February, 2013
John Le Heron
Radiation Protection of Patients Unit
Radiation Safety and Monitoring Section
Division for Radiation, Transport and Waste Safety
IAEA
International Atomic Energy Agency
Outline
• Background & current issues
• The BSS and radiation protection in medical
exposures
• IAEA activities & resources in TSA 3
• DRLs and the BSS
IAEA
Medical exposures – current usage
Every year, throughout the world, ionizing radiation is used in*:
• 4.000.000.000 diagnostic procedures
• 35.000.000 nuclear medicine procedures
• 8.000.000 radiotherapy treatment courses
These bring huge
benefit to healthcare
* An expanding activity worldwide
Diagnostic procedure
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Nuclear medicine procedure
Radiotherapy procedure
*UNSCEAR 2008
Increasing use of radiation in medicine
• More machines, etc
• New technologies and techniques
Single slice CT → Multi-Detector CT
Film → Computed & Digital Radiography
Hybrid imaging, PET-CT
Image-guided interventional procedures
Virtual procedures
• New roles
E.g. Changes in the role of imaging:
First “port of call”
A move towards “screening”, in all its guises
• Increasing complexity in the planning
& delivery of the radiation
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E.g. IMRT, IGRT, etc.
Is this increasing use of radiation in medicine
cause for concern?
What are some of the current issues
in imaging?
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Patient doses – a perspective
• Depends on the radiological procedure
Whole body dose
• E.g. Radiology:
• Radiation therapy
• Many tens of Gy (but only to target vol)
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LD50 3000 - 5000 mSv
X ray exams
• Radiography
• A few μSv to a few mSv, per procedure
• CT
• A few mSv to tens of mSv
• Image-guided interventional procedures
• A few mSv to tens of mSv
• Skin doses up to several 1000 mSv
NBR, 2.4 mSv
Radiography
• Doses to the patient are typically low
• Effective dose – a few μSv to a few mSv
• But variation by a factor of 20 more
• Many exams lack proper justification and/or
optimization
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Image-Guided Interventional Procedures
• Increase continues, in some countries doubling
every 2 - 4 years
• Doses can be high
• Effective doses
• Can exceed 20 mSv
• Peak skin doses
• Can exceed several Gy
• Repeat procedures – not insignificant
• Health professionals involved may not have had
radiation protection training
• Optimization often lacking
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CT
Level I - UNSCEAR 2008
• Usage increasing
• More scanners
• Quicker to use
• Can do more with them
• But issues with:
• Justification
• Unnecessary exams
• Self-referral
• Pressure for
“screening”
• Optimization
• Children
• Multiple follow-up
examinations
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43%
47%
CT
Nuclear Medicine
Interventional
Conventional Rad/fluoro
4%
6%
A need for radiation protection of the patient
Radiation dose
Achieve clinical purpose
• ICRP principles of radiation protection
• Justification
• Net benefit for the patient
• Optimization
• Achieve clinical purpose with appropriate dose
management
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RP regulatory framework for medical exposure
• The old BSS and the new BSS
• The BSS sets out the requirements for Medical Exposure
• Medical Exposure often called “TSA 3” in IAEA projects
• Thematic Safety Area 3
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IAEA projects and TSA 3
• Directed at end-users – medical radiation facilities
• All hospitals and medical centres in a Member State
where radiation is used in medical applications
• i.e. From large teaching hospitals to small rural units
• All modalities, as applicable
• Diagnostic radiology
• Radiography, fluoroscopy, CT, mammography, dental, DEXA
• Image guided interventional procedures
• Nuclear medicine
• Radiation therapy
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TSA 3 – for each medical radiation facility:
• Appropriate persons are in place to take the
relevant responsibilities
• Radiological medical practitioners
• Medical radiation technologists
• Medical physicists
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TSA 3 – for each medical radiation facility:
• The radiation protection principle of
justification is being applied
• In particular, “Level 3” for individual justification
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TSA 3 – for each medical radiation facility:
• The principle of optimization of protection is
being applied to every exposure
• Design considerations for equipment
• Operational considerations
• Calibration
• Dosimetry of patients
• DRLs
• Quality assurance for medical exposures
• Dose constraints
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TSA 3 – for each medical radiation facility:
• Unintended and accidental medical
exposures are being addressed
• Means for minimizing their likelihood
• If they occur:
• Appropriate investigations
• Appropriate corrective actions
• Written records
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Some IAEA activities to help Member States
with radiation protection of the patient
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Dedicated website
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Dedicated website – rpop.iaea.org
Updated monthly
Information for
• Health
professionals
• Member States
• Patients
Additional resources
• Publications
• Safety
Standards
• Training material
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Developing Standards
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The new BSS
• Basis for RP in medical exposures
• Safety Guide
• RP in medical facilities (being developed)
• Safety Report Series
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•
•
•
Newer medical imaging techniques
Guidelines for the release of patients after radionuclide therapy
Establishing guidance levels in X ray guided medical
interventional procedures
All available from RPoP website
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Promoting Education and Training
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Promoting Education and Training
• Development of standard packages for training in
the application of the safety standards
Approved Training Package
IAEA Training Material on
Radiation Protection in Cardiology
• Approved training packages on:
• Radiation protection in:
• Diagnostic and interventional radiology
• Nuclear medicine
• Radiotherapy
• Cardiology
• PET/CT
• Paediatric radiology
• Prevention of accidental exposure in radiotherapy
Lessons from injured patients:
Cumulative buildup
of dose for steeply
angled high-dose
beam through large
patient not
recognized.
Threshold
Preventable
Lesion required grafting.
Physical factors and challenges to
radiation management
Factors affecting patient
doses (I)
THE USE OF
THE
ANTISCATTER
GRID
improper filtering
proper filtering
in collaboration with
Version: April 2009
Training material also available for free download from
http://rpop.iaea.org
• Dissemination of training material
• Downloadable from RPoP website or available as CD
• Organization of training courses
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Thicker tissue masses absorb more
radiation
INCREASES
PATIENT
ENTRANCE
DOSE BY A
FACTOR OF 2
TO 6
Technical Assistance
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Technical Cooperation
• Through regional and national projects:
• Procurement for Member States
• QC kits, phantoms, dosimeters, publications, etc
• Fellowships & Scientific Visits
• Expert missions
• Regional & national training courses
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Diagnostic Reference Levels & the BSS
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120
The advent of DRLs
100
Abdomen AP – NZ, 1983
Number
80
60
40
20
0
0-
1.0 -
2.0 -
3.0 -
Effective dose (m Sv)
• Large variations in patient doses for the same
exam have been long documented
• Many factors influence patient dose and image quality
• The need for improvement long recognized
• Various approaches advocated in 70s, 80s
• E.g. Patient exposure guides (USA)
• International recommendations
• ICRP first mentioned “DRLs” in Publication 60, 1990
• Elaborated in Publication 73, 1996
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4.0 -
> 5.0
The IAEA and DRLs
• The International BSS, 1996
• Introduced Guidance Levels for medical exposure
• Concept same as DRLs
• Revised International BSS, 2011
• DRLs continue as an important tool for
optimization of patient radiation protection in
imaging
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What does the new BSS require?
• 2 aspects
• Establishing (national) DRLs
• Using the DRLs
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Establishing national DRLs - BSS
• Who?
• Government as the
facilitator
• Health Authority
• Professional Bodies
• Regulatory Body
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Establishing national DRLs - BSS
• For what procedures?
• Medical imaging
• Including image guided interventional procedures
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Using national DRLs - BSS
• The (radiation protection) Regulatory Body
mandates the use of the nationally
established DRLs
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Using national DRLs - BSS
• At each medical radiation facility
• Local assessments of typical doses for common
procedures
• Results compared with relevant DRLs, and if:
• Exceed the relevant DRLs; or
• Substantially below the relevant DRL and images
not of diagnostic quality
• Review of adequacy of optimization of patient
radiation protection
• Corrective action, if indicated
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How DRLs work – a trigger for review
• National DRLs have been established
• Typical doses at a facility are
DRL based on 75th
percentile
periodically compared with the
relevant DRLs
• If exceeds DRL, or
• If significantly below DRL and there are IQ
problems
• Investigate and if needed improve
optimization
Average ESD
Room AA = 4.4 mGy
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Average ESD
Room BB = 6.9 mGy
Note: if below DRL, still may not be optimized
What are the features of DRLs?
• Applicable to a country or region within a country
• Values established, in consultation, by
• Professional bodies, Health Authority, RP Regulatory Body
• For common examinations
• In setting values, the following must be considered
•
•
•
•
•
•
Clinical requirements – general or specific
Adequate image quality
Use of easily measured dose quantities
Data from wide-spread surveys
Standardised patient or phantom
Need for revision as technology and techniques improve
All of these will be discussed many times this week
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In setting DRLs
• Adequate image quality
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Example – Image Quality & Mammography
• 1990s, MGD increased
• Image quality demands,
including
• Need for higher contrast
• New film developed, higher
density needed
• Clinical requirements must be the
driver
• DRLs must not be an impediment
to such developments
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* D Spelic, et al. Biomed Imaging and Interv 2007; 3(2):e35
Setting a DRL value for a procedure performed
with different technologies and techniques
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Example – Dental intra-oral radiography
• Most common dental
exam is the posterior
“bitewing” view
• Direct exposure film
• D-speed
• E/F-speed
• Digital imaging
• DR (mainly)
• CR
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www.michigan.gov/mdch/0,1607,7-132-27417_35791_35798-46657--,00.htm
M Alcaraz et al. Radiation Protection Dosimetry (2010) 140(4),391-5
Dental doses – intra-oral
• Depends on the image receptor
• Depends on the kVp, etc.
• Factor of 5 in the example
• Should the setting of DRLs
accommodate all current practice
or be technology specific?
• National DRLs are based on
wide-spread surveys
• Blunt instrument
• In parallel, the professional
bodies must take the initiative
• e.g. American Dental Association
•
Dentists should use E/F-speed film
• In time, DRLs would reflect this
professional body guidance
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http://www.michigan.gov/mdch/0,1607,7-132-27417_35791_35798-46657--,00.html
• DRLs reflect immediate-past practice in a
given country, “warts and all”, applied
prospectively
• Therefore, the periodic review of DRLs is
very important
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Patient size
• The concept of a DRL is based on a typical patient,
either:
• A phantom, or
• Patients selected on basis of some criteria
• Does “looking after” this standardised patient
ensure that all patients are ok?
• Does an adult DRL help ensure optimization for a child?
• Experience has shown that the answer is “No”
• There is a need for a range of “standardised patients”
• E.g. several paediatric sizes
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Setting DRL values – not all exams are equal
• DRLs for projection radiography are relatively easy
• But with other modalities it is more difficult
• Image Guided Interventional Procedures (IGIPs)
• Factors include
•
•
•
•
•
Operator skill and experience
Patient size and anatomy
Complexity of the task
Equipment
Routine versus emergency
• DRLs for IGIPs need to reflect the overall system
• DRLs for IGIPs are not appropriate for deterministic effects
• DRLs are not used for individual patients
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DRL values and the new BSS
• The new BSS gives no values
• The old BSS did (Schedule III)
• The new Safety Guide will discuss values of
DRLs in use
• Preference is for each country (or region in a
country) to have their own
• Based on the practice in their country
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Do DRLs work – Trends with time
• UK has > 20 years of experience with DRLs
• Reviews in 1995, 2000, 2005 and 2010
• 2010 review showed for radiography:
• On average about 16% lower than 2000 review
• Typically less than 50% of original DRLs
Trend due to better
optimization, including
regular monitoring of patient
doses
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HPA-CRCE-034, Health Protection Agency, UK, 2012
Implementation around the world
• Still a long way to go
• Many countries have introduced DRLs, but the
level of utilization varies widely
• Between countries, and within countries
• IAEA regional projects in patient protection
• Developing Member States in:
• Africa, Asia, Europe, Latin America
• Includes setting up DRLs
• Level of achievement to date is low
At RAF9044 RCM, DRLs were identified as the number 1 priority
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Regional meeting, Kampala, 18-22 Feb
• Aim
• To describe, using teaching, practical work and
group discussion, the concepts and
methodologies that will enable participants to
facilitate in their own countries the:
• Establishment (and periodic review) of national DRLs,
and
• Application and use of DRLs in their country’s
hospitals
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Summary
• BSS sets out the requirements for patient radiation
protection
• Optimization of protection is a cornerstone of
patient radiation protection
• DRLs are an important tool for optimization
• Need to be established
• Need to be used
• Need to be reviewed periodically
IAEA