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IAEAInternational Atomic Energy Agency
RADIATION PROTECTION INDIAGNOSTIC AND
INTERVENTIONAL RADIOLOGY
L 01. Overview of Radiation Protection in Diagnostic & Interventional Radiology
Motivation for the Course
IAEA Training Material on Radiation Protection in Diagnostic and Interventional RadiologyAdapted for Regional Training Course on RP of Patients for Radiographers
Accra, Ghana, 11-15 July 2011
IAEA Introduction to Radiation Protection in Diagnostic Radiology 2
Introduction
• An overview of medical uses of radiation• Radiation protection issues in diagnostic &
interventional radiology
IAEA Introduction to Radiation Protection in Diagnostic Radiology 3
Current use of radiation in medicine
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
- An expanding activity worldwide
- Impacts on large portion of global population
Diagnostic procedure Nuclear medicine procedure Radiotherapy procedure
These bring huge benefit to healthcare
*UNSCEAR 2010
IAEA Introduction to Radiation Protection in Diagnostic Radiology 4
Increasing use of radiation in medical applications worldwide• More machines, etc
• New technologies and techniques
• New roles
• Increasing complexity in the planning & delivery of the radiation
Single slice CT → Multi-Detector CTFilm → Computed & Digital RadiographyHybrid imaging, PET-CT
Image-guided interventional proceduresVirtual procedures
E.g. Changes in the role of imaging: First “port of call”
A move towards “screening”, in all its guises
E.g. IMRT, IGRT, etc.
IAEA 5
UNSCEAR UNSCEAR 19931993
GlobalGlobal annual per caput effective dose annual per caput effective dose
Increasing medical exposure
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UNSCEAR UNSCEAR 20002000
GlobalGlobal annual per caput effective dose annual per caput effective dose
Increasing medical exposure
IAEA 7
UNSCEAR UNSCEAR 20082008
GlobalGlobal annual per caput effective dose annual per caput effective dose
Increasing medical exposure
IAEA 8
NCRP160 NCRP160 20092009
U.S.U.S. annual per caput effective dose annual per caput effective dose
Increasing medical exposure
IAEA Introduction to Radiation Protection in Diagnostic Radiology 9
Collective dose from medical exposures
Relative contribution – Level I versus USA
Relative contribution to collective dose
0%
10%
20%
30%
40%
50%
60%
CT Nuclear Medicine Interventional ConventionalRad/fluoro
Per
cen
tag
e
USA
Level I
IAEA Introduction to Radiation Protection in Diagnostic Radiology 10
Context – another reality
However, However, reports continuereports continue to appear on: to appear on:
• Accidental and unintended exposures
• Unnecessary exposures
Advertisement for radiological screening gift certificatesNewspaper report on recent radiotherapy accident
IAEA Introduction to Radiation Protection in Diagnostic Radiology 11
Is this increasing use of radiation in medicine cause for concern?
How do patient doses compare with other sources of exposure?
IAEA Introduction to Radiation Protection in Diagnostic Radiology 12
Radiation from Natural Sources
• Normally 1-3 mSv/year
• Global average is estimated to be 2.4 mSv per year (UNSCEAR)
• In areas of high background, > 10 mSv/year
IAEA Introduction to Radiation Protection in Diagnostic Radiology 13
Patient effective doses
• Depends on the radiological procedure
• E.g. • Radiography
• A few μSv to a few mSv
• 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 mSvNBR, 2.4 mSv
LD50 3000 - 5000 mSv
Whole body dose
X ray exams
IAEA Introduction to Radiation Protection in Diagnostic Radiology 14
What are some of the RP issues in diagnostic and interventional radiology?
IAEA Introduction to Radiation Protection in Diagnostic Radiology 15
What are the issues - radiography?
Staff doses are typically very low• < 1 mSv per year
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
Hospital ADose = X
Hospital CDose = 10X
Hospital BDose = 2X
IAEA Introduction to Radiation Protection in Diagnostic Radiology 16
Radiography
• Diagnostic reference levels (DRLs)• Very effective tool in optimization
• Concept introduced in the 1990s
• Implementation in Member States is very uneven• How many African countries have
• Established DRLs; and
• Use them in practice?
IAEA Introduction to Radiation Protection in Diagnostic Radiology 17
In radiographic practice, does it happen?
• Unjustified exposures - Yes
• Wrong patient - Yes
• Wrong body part - Yes
• Lack of optimization - Yes • Lack of calibration – Yes
• Lack of QA – Yes
• DRLs not used - Yes
IAEA Introduction to Radiation Protection in Diagnostic Radiology 18
Fluoroscopic examinations - diagnostic
• Staff doses are typically low
• Doses to the patient are typically a few mSv
• But variation through lack of optimization
IAEA Introduction to Radiation Protection in Diagnostic Radiology 19
Image-Guided Interventional Procedures
• Increase in use continues, in some countries doubling every 2 - 4 years
• Who are the patients?• Mostly adults, > 40 years old
• But also children, ~ 5 %
• Doses can be high• Effective doses
• Can exceed 20 mSv
• Peak skin doses• Can exceed several Gy
IAEA Introduction to Radiation Protection in Diagnostic Radiology 20
Number of procedures per
patient1 2 3 4 5 6 7 >7
Number of patients
1967
940 194 138 41 29 14 9
Nearly 6% of patients had 3 or more interventions
Udine, Italy – Cardiac Interventions Analysis of > 3000 patients
Repeat procedures – not insignificant
IAEA Introduction to Radiation Protection in Diagnostic Radiology 21
Induced lens opacities
Reference: Vañó E et al, BJR 1998; 71, 728-733
Image-Guided Interventional Procedures
• Staff issues
IAEA Introduction to Radiation Protection in Diagnostic Radiology 22
Image-Guided Interventional Procedures
• Increasing frequency
• High doses
• Paediatric patients
• Repeat rate not insignificant
• Radiation protection issues for staff
IAEA Introduction to Radiation Protection in Diagnostic Radiology 23
CT
• Usage increasing• More scanners• Quicker to use• Can do more with them
• Staff doses low at console, but hand doses of concern in CT fluoroscopy
• Patient doses• Effective doses 1 – 10 mSv• But can exceed 20 mSv
• Many patient dose reduction tools now available• But optimization often not happening
Level I - UNSCEAR 2008
43%
6%4%
47% CT
Nuclear Medicine
Interventional
Conventional Rad/f luoro
IAEA Introduction to Radiation Protection in Diagnostic Radiology 24
CT
• But issues with:• Justification
• Unnecessary exams
• Self-referral
• Pressure through media for “screening”
IAEA Introduction to Radiation Protection in Diagnostic Radiology 25
CT
• Issues with:• Multiple follow-up examinations
Hospital in Boston - 22 years of CT
Number of CT exams:
33% of patients - 5 or more CT exams
5% - between 22 & 132 CT exams
Cumulative doses:
15 % - greater than 100 mSv
4 % - between 250 & 1375 mSv
IAEA Introduction to Radiation Protection in Diagnostic Radiology 26
CT
• Issues with children• Increasing number of children
undergoing CT examinations• E.g. in USA (Mettler, 2000)
• 1989 ~ 4 % of all CT scans
• 1993 ~ 6 %
• 2000 ~ 11 %
• Optimization not always implemented
IAEA Introduction to Radiation Protection in Diagnostic Radiology 27
Deterministic Effects in CT?
Stroke protocol plus angiography caused temporary hair loss in this study
CT dose 2-3 Gy; angiography dose?
Yoshimasa Imanishi et al Eur Radiol (2005) 15:41–46
IAEA Introduction to Radiation Protection in Diagnostic Radiology 28
Principles of radiation protection
• Justification
• Optimization
• Dose limitation (not for patients)
In Practice:
• Unjustified examinations are ≈ 20-50%
• Optimization can bring down patient doses by about 50%
IAEA
Radiographers make a difference
Introduction to Radiation Protection in Diagnostic Radiology 29
The radiographer's attention to imaging details, such as chamber positioning, mAs and kVp settings, have helped reduce radiation exposure during lumbar x-ray studies at the Haukipudas Health Center in northwest Finland.
Radiographers reduce radiation exposure in Finland – 2011 ECR
April 18, 2011 – Radiographers have an important role to play in monitoring patient radiation exposure and adjusting x-ray equipment settings when rates rise, according to Finnish researchers.
IAEA Introduction to Radiation Protection in Diagnostic Radiology 30
Summary
1. Medical uses of radiation are increasing, bringing great benefit
2. But there is a need to reduce unnecessary exposures
3. Radiographers have a key role to play