1. Medical exposure in radiology: Guidance or Reference Levels
Module VIII.3 - Part 4: Guidance levels for the patients

2. Introduction
In general, in medical exposure there are no dose limits or constraints
Dose reference (DRL) or guidance levels are tools to optimize procedures and equipment use
We will see how to establish them and give some examples of values and discuss their usefulness
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

3. Medical exposure framework and reference doses
Topics
Medical Exposure
Medical exposure framework and reference doses
Medical exposure dose constraints for comforters and in research
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

4. Overview Overview of types of radiation exposure
Dose limits, dose constraints
Justification and optimization
Dose guidance/reference level definition
How to establish them
How to use them
Examples of dose reference levels
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

5. Topic 1: Medical exposure framework and reference doses

6. Types of exposure Medical Exposure: Occupational Exposure:
principally the exposure of persons as part of their diagnosis (or treatment)
Occupational Exposure:
exposure incurred at work, and practically as a result of work
Public Exposure:
all other exposures
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

7. What is a medical exposure?
Exposure of persons as part of their diagnosis or treatment
Additionally:
Exposures (other than occupational) incurred knowingly and willingly by individuals such as family and close friends helping either in hospital or at home in the support and comfort of patients
Exposures incurred by volunteers as part of a program of biomedical research
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

8. What is occupational exposure?
All exposures of workers incurred in the course of their work.
[excepted the exposures excluded from the Standards (see Basic Safety Standards) and exposures from practices or sources exempted by the Standards]
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

9. What is exposure of the public?
ALL exposures not falling in the two other categories
effective dose of 1mSv in a year
in special circumstances, effective dose of 5mSv in a single year, provided that the average over five consecutive years in less than 1mSv per year
equivalent dose to lens of the eye 15mSv in a year
equivalent dose to skin of 50mSv in a year
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

10. Overview Dose limits (ICRP60)
Occupational dose limit
Public dose limit
Effective dose
20mSv/y, averaged over 5 y
1 mSv/y
Annual effective dose in:
Lens of eye
150mSv
15mSv
Skin
500mSv
50mSv
Hands and feet -
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

11. Topic 2: Medical exposure framework and reference doses

12. Question 1
Mr. Sharp, I am given to understand that 2 CT examinations performed on me have given me 25 mSv whereas 20 mSv is the safe dose. I want to file legal suit against the doctor.
What do you feel ??
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

13. Question 2
My resident doctor has got 12 mSv in her last badge report as she was wearing the badge while getting her barium study. She wants off from radiation work.
?????
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

14. Medical exposure framework
Justification
Optimization
The use of doses limits is NOT APPLICABLE
As an aid to keep doses as low as reasonably achievable:
Dose constraints and guidance (or reference) levels ARE RECOMMENDED
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

15. Justification: 3 levels
Review benefits and disadvantages !
General level:
Use of radiation in medicine is doing more good than harm
Generic level:
By national professional bodies
Specific procedure with a specific objective: chest radiographs for patients showing relevant symptoms
Individual level:
Application of the procedure to an individual patient
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

16. Sharing responsibility: the referring physician
A useful investigation is one in which the result —positive or negative — will alter management or add confidence to the clinician’s diagnosis.
The chief causes of the wasteful use of radiology are:
Repeating investigations which have already been done
Investigation when results are unlikely to affect patient management
Doing the wrong investigation
Failing to provide appropriate clinical information and questions that the imaging investigation should answer
Doing the wrong investigation.
The responsibility for patient dose is shared by the radiology department AND the referral physician
A useful investigation is one in which the result —positive or negative — will alter management or add confidence to the clinician’s diagnosis. A significant number of radiological investigations do not fulfil these aims and may add unnecessarily to patient irradiation (14). The chief causes of the wasteful use of radiology are:
(1) Repeating investigations which have already been done: e.g. at another hospital, in an
outpatient department, or in the accident and emergency department.
HAS IT BEEN DONE ALREADY? Every attempt should be made to get previous films. Transfer of digital data through electronic links may assist in this respect in future years.
(2) Investigation when results are unlikely to affect patient management: because the
anticipated ‘positive’ finding is usually irrelevant, e.g. degenerative spinal disease (as ‘normal’ as grey hairs from early middle age) or because a positive finding is so unlikely.
DO I NEED IT?
(3) Investigating too often: i.e. before the disease could have progressed or resolved or before the results could influence treatment. DO I NEED IT NOW?
(4) Doing the wrong investigation. Imaging techniques are developing rapidly. It is often helpful to discuss an investigation with a specialist in clinical radiology or nuclearmedicine before it is requested. IS THIS THE BEST INVESTIGATION?
(5)Failing to provide appropriate clinical information and questions that the imaging
investigation should answer. Deficiencies here may lead to the wrong technique being used (e.g. the omission of an essential view). HAVE I
EXPLAINED THE PROBLEM?
(6) Over-investigating. Some clinicians tend to rely on investigations more than others. Some patients take comfort in being investigated.
ARE TOO MANY INVESTIGATIONS BEING PERFORMED?
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

17. Since no dose LIMITS, there is a need for indicator for optimization:
Optimization is usually applied at two levels:
The design and construction of equipment and installations
Day to day radiological practice (procedures)
The optimization means that doses should be “as low as reasonably achievable, economic and social factors being taken into account” compatible with achieving the required objective
The optimization of protection in diagnostic radiology does not necessarily mean the reduction of doses to the patient (ex: antiscatter grid)
Since no dose LIMITS, there is a need for indicator for optimization:
GUIDANCE LEVELS
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

18. What is a guidance or reference level?
A value of dose, dose rate or activity selected by professional bodies in consultation with the Regulatory Authority to indicate a level above which there should be a review by medical practitioners in order to determine whether or not the value is excessive, taking into account the particular circumstances and applying sound clinical judgment (BSS) OR
dose levels in medical radiodiagnostic practices for typical examinations for groups of standard-sized patients or standard phantoms for broadly defined types of equipment; these levels are expected not to be exceeded for standard procedures when good and normal practice regarding diagnostic and technical performance is applied (Med. Direct. EUR97/43)
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

19. Guidance levels The guidance levels are intended:
(a) to be a reasonable indication of doses for average sized patients
(b) to be established by relevant professional bodies in consultation with the local Regulatory Authority
(c) to provide guidance on what is achievable with current good practice rather than on what should be considered optimum performance
(d) to be applied with flexibility to allow higher exposures if these are indicated by sound clinical judgement
(e) to be revised as technology and techniques improve
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

20. Use of the dose reference levels (DRL)
Act as investigation levels, triggering a local investigation if typical dose for specific type of diagnostic procedure is found consistently to exceed the relevant DRL
Simple test for identifying situations where patient doses are becoming unusually high and action is required
Corrective action is compulsory: on the procedure, on the equipment,…
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

21. Other practical aspects
Quantities used as guidance (or reference) levels should be understood by radiologists and radiographers (safety culture)
DRL are not applicable to individual patients. Comparison with DRL shall be only made using mean values of a sample of patients
DRL should be "flexible" (tolerances should be established: different patient sizes, different pathologies, etc). DRL are not a border line between good and bad medicine
The main objective of DRL is their use in a dynamic and continuous process of optimization
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

22. How to set the DRL value?
Pragmatic: use the 3rd quartile value of wide scale surveys
If 75% of X Ray depths can operate satisfactory BELOW
The remaining 25% should be made aware of their less than optimum performance
ICRP73 recommended that:“...initial
DRL values be chosen as a percentile point on the observed distribution of dose to patients.”
The “Nordic Guidance Levels for Patient Dose in Diagnostic Radiology” (1996) uses values closer to the mean value
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

23. When no surveys are available?
Do not reinvent the wheel
Regulating Authority/Professional body can adopt DRL’s from country with similar medical infrastructure
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

24. DRL checks forms part of QA program
Why no LOWER level?
Examinations with very low exposure usually give not enough diagnostic information, why no lower limit?
DRL checks forms part of QA program
Such program will include more than dose criteria
Including image quality and diagnostic efficacy
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

25. Dose quantities for monitoring ESD
Conventional radiology
ESD Entrance surface dose
TLD attached to skin where centre of X Ray beam enters patient
Or calculated from output measurements made in free air with ionization chamber during QA procedures corrected for backscatter (in radiology between )
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

26. Dose quantities for monitoring: DAP
Conventional and fluoroscopy
DAP Dose area product meter
Attached to diaphragm housing
Total DAP value (radiography + fluoroscopy) can be read out per examination or as time sequence
For fluoroscopy DRL are sometimes given in “Dose RATE Guidance Levels”
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

27. Dose quantities for monitoring: CT
Nominal slice width
CTDI
Dose profile
Computed tomography
Weighted CTDI per CT slice (analog to ESD)
Dose-Length product per exam (analog to DAP)
Multiple San Dose Average (MSAD)
Can only be determined on phantoms, not on patients
MSAD
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

28. Examples of guidance levels
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

29. Entrance surface dose per radiograph (mGy)
Guidance or reference levels for diagnostic radiography (typical adult patient)
1.5
Chest LAT
0.4
Chest PA 10
Hip joint AP
Pelvis AP
Entrance surface dose per radiograph (mGy)
Examination
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

30. Entrance surface dose per radiograph (mGy)
Guidance or reference levels for diagnostic radiography (typical adult patient) 5
Dental AP 7
Dental peri-apical 20
Thoracic spine LAT
Thoracic spine AP
Entrance surface dose per radiograph (mGy)
Examination
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

31. Entrance surface dose per radiograph (mGy)
Guidance or reference levels for diagnostic radiography (typical adult patient)
Dose values are in air with backscatter. They are for conventional film-screen combination (200 speed class). For higher speed film-screen combinations ( ), the values should be reduced by a factor of 2 to 3. 3
Skull LAT 5
Skull AP
Entrance surface dose per radiograph (mGy)
Examination
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

32. Dose guidance levels in CT (typical adult patient)
(a) Derived from measurements on the axis of rotation in water equivalent phantoms, 15 cm in length and 16 cm (head) and 30 cm (lumbar spine and abdomen) in diameter. 25
Abdomen 35
Lumbar spine 50
Head
Multiple scan average dose (mGy) (a)
Examination
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

33. Dose guidance levels for mammography
Determined in a 4.5 cm compressed breast consisting of 50% glandular and 50% adipose tissue, for film-screen systems and dedicated Mo-target/Mo-filter mammography units
1 mGy (without grid)
3 mGy (with grid)
Average glandular dose per craniocaudal projection
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

34. Dose rate guidance levels for fluoroscopy (typical adult patient)
(a) In air with backscatter
(b) For fluoroscopes that have an optional 'high level' operational mode, such as those frequently used in interventional radiology
100
High Level (b) 25
Normal
Entrance surface dose rate (mGy/min) (a)
Operation Mode
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

35. DRL’s in Pediatrics, for standard five-year-old patients, for single views
(from EUR-16261)
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

36. Medical exposure dose constraints for comforters and in research
Special cases
Medical exposure dose constraints for comforters and in research

37. Medical exposure dose constraints
For medical exposure normally no dose constraints are used, only guidance levels
Only for the protection of persons exposed for medical research purposes, or of persons, other than workers, who assist in the care, support or comfort of exposed patients dose constraints are applicable
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

38. Helping persons Severely ill patients require assisting persons
Partially cooperating pediatric patients, especially after trauma or with severe pain, need holding persons to stabilize the patient’s position for exact exposure
Ideally, no holding persons should be involved in radiography and fluoroscopy of patients
If at all possible, the helping person should be a technician or a nurse
Parents present can and often will hold their child
If female persons assist the radiographer or the radiologist, they should be asked about a possible pregnancy.
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

39. ( CIOMS: Council for International Organizations of Medical Sciences)
Medical research
The exposure of humans for medical research is deemed to be not justified unless it is:
(a) in accordance with the provisions of the Helsinki Declaration16 and follows the guidelines for its application prepared by CIOMS and WHO;
(b) subject to the advice of an Ethical Review Committee (or any other institutional body assigned similar functions by national authorities) and to applicable national and local regulations.
( CIOMS: Council for International Organizations of Medical Sciences)
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

40. What we learned Medical exposure is not subjected to dose limits
Basic principle is to comply with ALARA, justification and optimization
Dose reference levels are tools to optimize procedures and equipment use
A regular check has to be made of actual given doses with DRL’s
Examples are given of accepted DRL’s for standard patients and common procedures
Dose constraints are applicable for comforters and persons exposed in research
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

41. Where to get more information
International Basic Safety Standards for Protection Against Ionizing Radiation and for the Safety of Radiation Sources. 115, Safety Standards. IAEA, February 1996.
Radioprotection 102. Implementation of the medical Directive 97/43. pp Available at website:
Referral Criteria for Imaging. Radiation Protection 118. Adapted by experts representing European Radiology and Nuclear Medicine. In conjunction with the UK Royal College of Radiologists. Coordinated by the European Commission. Directorate General for the Environment. Luxembourg, Available at:website
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients

42. Where to get more information
ICRP 73. Radiological Protection and Safety in Medicine. Annals of the ICRP, 26(2), 1996.
WORLD HEALTH ORGANIZATION, Use of Ionizing Radiation and Radionuclides on Human Beings for Medical Research, Training and Non-Medical Purposes, Technical Report Series No. 611, WHO, Geneva (1977).
Guidance levelsModule VIII.3 Part 4: Guidance levels for patients