BEIR VII Implications of the Report for the Future of Medical Imaging G. Donald Frey, Ph.D. Department of Radiology Medical University of South Carolina

BEIR VII-Key Results The report supports the LNT model. The radiations risk values are “similar” to previous reports and other groups like UNSCEAR and ICRP. The uncertainties have been reduced for lower dose.

Radiation Dose from Medical Imaging “The Historical View” The radiation dose from medical imaging was low and a small fraction of the dose from natural sources. Imaging was viewed as being done only when clearly needed so it was well justified. The data on radiation effects was seen as uncertain at doses that would overlap the range of common medical procedures.

Dose Risk

Dose Risk Medical Imaging

Dose Risk Medical Imaging

Dose Risk Medical Imaging Recently - Doses from Imaging Have Increased

Dose Risk Medical Imaging BEIR VII - The Degree of Uncertainty Has Decreased

BEIR VII Suggests We need to pay more attention to the justification of medical imaging. Practitioners should be well informed about #The medical aspects of the procedure so that it can be justified, #The radiation risks from the procedure, and #The medical physics aspects of the procedure so it can be optimized.

BEIR VII Suggests We need to pay more attention to ALARA to insure that properly justified procedures are properly done #Optimization of the dose-image quality tradeoff #Robust quality assurance techniques to insure high quality images

Recent Developments In Imaging Great increases in the number of imaging studies Increased use of higher dose techniques #Computed Tomography #Fluoroscopy

Change in the Number of Imaging Procedures Maitino et al Radiology 2003;227:

Levin JACR 2006;3: % +29% Rate Changes

Dose and Collective Dose CT accounts for 15% of procedures CT accounts for 75% of the total effective dose Wiest et al Sem in US, CT & MRI 2002, 23;

US Exposures NCRP 93

Huda-Frey Estimate 2.8 mSv

Levin JACR 2006;3:90-95 Unacceptable Image Quality: Pennsylvania Blue Shield Study How Well is Imaging Done?

Are Practitioners Knowledgeable About Radiation Dose and Dose Effects?

Changes in the Medical Imaging Environment The uncertainties about radiation effects have decreased. The number of imaging procedures have increased. The increase has been highest in the high dose studies (CT). It is not obvious that all studies are well justified.

How Are These Issues Addressed? Federal Law & Regulation Federal Payment Structure State Law & Regulation Professional Societies Business and Insurance Public

Professional Societies The AAPM and ACR have undertaken a number of initiatives to address these problems #Accreditation programs #Task Group Reports CTDI Values DR Exposure Index

Professional Society – Regulatory Partnership Cooperation between the regulatory community and professional societies can work to reduce the effects of these many problems.

Some Suggested Approaches & Some Current Activities

Practitioners Practitioners who use fluoroscopy or direct CT examinations should be able to demonstrate knowledge of: #Radiation effects #Radiation risks #Basic physics of the modality #Image optimization

Practitioners Regulation like that used to determine status as an authorized user in Part 35 would be prudent and relevant.

Medical Physicists Medical physicists play a key roles in: #Radiation protection #Image optimization #Definition and supervision of quality assurance Many state regulations are based on obsolete roles for diagnostic medical physicists.

Medical Physicists Limitations in existing State regulations mean that individuals who act as medical physicists can often lack the knowledge to #Properly optimize image quality #Design and specify proper quality assurance programs

Medical Physicists Existing State regulations have created a group of “diagnostic physicists” who can only deal with prescriptive regulations But cannot #Optimize image quality #Provide effective quality assurance programs

Medical Physicists State Regulations should require that medical physicists should be able to demonstrate competence. The AAPM definition of a qualified medical physicist should form the basis of standards which would be used to define the competence of a medical physicist.

Medical Physicists New regulations should concentrate on establishing the competence of medical physicists and then allow medical physicists to exercise their professional judgment in many areas Prescriptive regulations cannot keep up with the rapid changes in medical equipment so professional judgment is required

Equipment Regulations Difficult because of rapid changes in equipment Also regulations have to encompass both new and old equipment

Current Regulation Stresses testing of details of equipment performance #There is frequently little or no evidence that specific items in these regulations protect the public in an effective way #They may create a false sense of security

False Sense of Security Equipment that meets regulations but produces poor images Equipment that meets regulations but is used poorly Reliance on CTDI values that significantly underestimate actual patient doses significantly distorts the situation

Issues with Current Regulations CT as an Example Dose testing is highly prescriptive but does not set standards Image quality does not set standards

CT as an Example Dose Measurement in SSR #Use phantom that underestimates the dose for most most body studies #Require measurements for each head, body or whole body scan #Do not set limitations for the measured values

CT Scanning Current SSR require image quality testing. However there is no minimum performance that is required. There is no definition of the phantom that is used.

How Might Regulation Be Improved? (CT as an Example) Dose testing should relate to national and international standards for reference doses. Testing should be done to insure an acceptable level of image quality. The image quality should be determined by reference to a national standard.

European Union Guidelines ExaminationCTDIw mGyDLP mGy-cm Routine Head601,050 Face & Sinus35360 Routine Chest30650 High Res Chest Routine Abdomen European Guidelines on quality criteria for CT (EUR 16262EN)

ACR CT Accreditation ExaminationCTDIw mGy Routine Head60 Adult Abdomen 35 Pediatric Abdomen 25

I Negus – Berreford Hospital, Plymouth, GD

Improved Regulation Image Quality Testing National Standard for Performance National Phantom This is commonly done for mammography and should be adopted for CT.

Image Quality Testing ACR accreditation testing National standard for performance

Quality Assurance Regulations cannot keep up with the rapid changes in imaging equipment. Qualified medical physicists should have some latitude in specifying quality assurance programs and image quality as long as the programs relate to a national standard.

Dose Tracking Trends The NEXT program has long been the standard for determining radiation dose trends. NEXT Data has been of great value in determining trends in use and dose.

NEXT Limitations Equipment has become more complex so it is difficult to make meaningful measurement. The variety of procedures changes rapidly so NEXT data tends to “lag” current practice.

Electronic Monitoring Modern equipment has the ability to collect dose data automatically. The medical and regulator communities should support efforts to collect and analyze this data in an automatic fashion.

Summary BEIR VII suggests we should be more concerned about high dose medical exposure. Recent data suggests that not all medical imaging is well justified or well done.

Summary Professional Societies (AAPM, ACR, etc) are aware of these problems The Regulatory Community (CRCPD) is also aware of these problems A strong partnership between these communities can address these problems in effective ways

Summary Regulatory Philosophies should change: #Insure that medical practitioners and medical physicists are well qualified and stay well qualified #Regulations should become more flexible in detail #Regulations should require testing to a national standard