1. Radiation Protection of Patients Unit
IAEA, the BSS and DRLs Regional Meeting on the Establishment and Utilization of Diagnostic Reference Levels Kampala, Uganda, February, 2013
John Le Heron
Radiation Protection of Patients Unit
Radiation Safety and Monitoring Section
Division for Radiation, Transport and Waste Safety

2. Outline Background & current issues
The BSS and radiation protection in medical exposures
IAEA activities & resources in TSA 3
DRLs and the BSS

3. Nuclear medicine procedure Radiotherapy procedure
Medical exposures – current usage
Every year, throughout the world, ionizing radiation is used in*:
diagnostic procedures
nuclear medicine procedures
radiotherapy treatment courses
* An expanding activity worldwide
These bring huge benefit to healthcare
Diagnostic procedure
Nuclear medicine procedure
Radiotherapy procedure
*UNSCEAR 2008

4. Increasing use of radiation in medicine
More machines, etc
New technologies and techniques
New roles
Increasing complexity in the planning & delivery of the radiation
Single slice CT → Multi-Detector CT
Film → Computed & Digital Radiography
Hybrid imaging, PET-CT
Image-guided interventional procedures
Virtual procedures
E.g. Changes in the role of imaging:
First “port of call”
A move towards “screening”, in all its guises
These changes since the early 1990s provide a backdrop to the current use of radiation in medical applications.
The reality is that the use of radiation in medical applications is increasing worldwide – more hardware, and more techniques and uses.
This is accompanied by an increasing complexity in how the radiation is delivered. Computer control is becoming the default, with a consequent de-coupling between the operator and the amount of radiation being used. Accidental medical exposures can and do occur.
All of these issues must be addressed in the revised BSS.
E.g. IMRT, IGRT, etc.

5. Is this increasing use of radiation in medicine cause for concern?
What are some of the current issues
in imaging?

6. Patient doses – a perspective
Depends on the radiological procedure
E.g. Radiology:
Radiography
A few μSv to a few mSv, per procedure CT
A few mSv to tens of mSv
Image-guided interventional procedures
Skin doses up to several 1000 mSv
Radiation therapy
Many tens of Gy (but only to target vol)
NBR, 2.4 mSv
LD mSv
Whole body dose
X ray exams

7. 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

8. Image-Guided Interventional Procedures
Increase continues, in some countries doubling every 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

9. CT Usage increasing But issues with: 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

10. 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

11. 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

12. 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

13. 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

14. TSA 3 – for each medical radiation facility:
The radiation protection principle of justification is being applied
In particular, “Level 3” for individual justification

15. 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

16. 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

17. Some IAEA activities to help Member States with radiation protection of the patient

18. Dedicated website

19. Dedicated website – rpop.iaea.org
Updated monthly
Information for
Health professionals
Member States
Patients
Additional resources
Publications
Safety Standards
Training material

20. Developing Standards

21. The new BSS Basis for RP in medical exposures Safety Guide
RP in medical facilities (being developed)
Safety Report Series
Newer medical imaging techniques
Guidelines for the release of patients after radionuclide therapy
Establishing guidance levels in X ray guided medical interventional procedures

22. All available from RPoP website

23. Promoting Education and Training

24. Promoting Education and Training
Development of standard packages for training in the application of the safety standards
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
Dissemination of training material
Downloadable from RPoP website or available as CD
Organization of training courses

25. Technical Assistance

26. 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

27. Diagnostic Reference Levels & the BSS

28. The advent of DRLs
Abdomen AP – NZ, 1983
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

29. 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

30. What does the new BSS require?
2 aspects
Establishing (national) DRLs
Using the DRLs

31. Establishing national DRLs - BSS
Who?
Government as the facilitator
Health Authority
Professional Bodies
Regulatory Body

32. Establishing national DRLs - BSS
For what procedures?
Medical imaging
Including image guided interventional procedures

33. Using national DRLs - BSS
The (radiation protection) Regulatory Body mandates the use of the nationally established DRLs

34. 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

35. How DRLs work – a trigger for review
National DRLs have been established
Typical doses at a facility are 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
DRL based on 75th percentile
Average ESD
Room AA = 4.4 mGy
Average ESD
Room BB = 6.9 mGy
Note: if below DRL, still may not be optimized

36. 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

37. In setting DRLs
Adequate image quality

38. 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
* D Spelic, et al. Biomed Imaging and Interv 2007; 3(2):e35

39. Setting a DRL value for a procedure performed with different technologies and techniques

40. 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
M Alcaraz et al. Radiation Protection Dosimetry (2010) 140(4),391-5

41. 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

42. DRLs reflect immediate-past practice in a given country, “warts and all”, applied prospectively
Therefore, the periodic review of DRLs is very important

43. 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

44. 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

45. 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

46. 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
HPA-CRCE-034, Health Protection Agency, UK, 2012

47. 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

48. 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

49. 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