lecture 01 overview rp in dr and ir rtc accra 2011

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


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


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.

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UNSCEAR UNSCEAR 19931993

GlobalGlobal annual per caput effective dose annual per caput effective dose

Increasing medical exposure

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NCRP160 NCRP160 20092009

U.S.U.S. annual per caput effective dose annual per caput effective dose



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


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


Is this increasing use of radiation in medicine cause for concern?

How do patient doses compare with other sources of exposure?


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


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


What are some of the RP issues in diagnostic and interventional radiology?


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


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?


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


Fluoroscopic examinations - diagnostic

• Staff doses are typically low

• Doses to the patient are typically a few mSv

• But variation through lack of optimization


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


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


Induced lens opacities

Reference: Vañó E et al, BJR 1998; 71, 728-733


• Staff issues



• Increasing frequency

• High doses

• Paediatric patients

• Repeat rate not insignificant

• Radiation protection issues for staff


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


CT

• But issues with:• Justification

• Unnecessary exams

• Self-referral

• Pressure through media for “screening”


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


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


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


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%

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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.


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

lecture 01 overview rp in dr and ir rtc accra 2011

Documents

caput effective dose

interventional radiology

diagnostic radiology

radiation protection

ct issues

diagnostic

exceed 20 msv

diagnostic