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Development of DRLs in the UK David Sutton  Ninewells Hospital & Medical School  Dundee, UK
Why have Diagnostic Reference Levels ? <ul><li>Radiation is harmful </li></ul><ul><li>Diagnosis is beneficial </li></ul><u...
Perceived image quality is task and reader dependent.
Radiologist A Radiologist  B
<ul><ul><li>What dose is just low enough  </li></ul></ul><ul><ul><li>& what image quality is just good enough  </li></ul><...
<ul><ul><li>It’s easier to decide that if the majority of radiologists agree that a particular dose range  results in imag...
What is a Diagnostic Reference Level ? <ul><li>A dose level for typical examinations for groups of standard-sized patients...
What is a Diagnostic Reference Level ? <ul><li>A level set using an arbitrary (i.e. not scientific) threshold in a distrib...
Historical Perspective
Historical Perspective – What is diagnostic? UK Survey of Patient Dose 1983-5 20 Hospitals 5 37 Pelvis AP 8 88 Abdomen AP ...
UK Survey of Patient Dose 1983-5
RCR “Patient Dose Reduction in Diagnostic Radiology 1990” <ul><li>“Some 1300 man Sv could be saved by persuading the 25% o...
ICRP 60 1991 <ul><li>Consideration should be given to the use of dose constraints or investigation levels selected by the ...
1992 – UK National Protocol  <ul><li>Practical guidance on comparing local performance with National Practice </li></ul><u...
Doses to patients from medical x-ray examinations  in the UK –  1995 review   <ul><li>50 000 patient dose measurements </l...
 
 
NRPB 2000 Review of Patient Doses
NRPB 2000 Review of Patient Doses
Revised EU Medical Exposures Directive (97/43/Euratom) : MED <ul><li>Article 4(2) </li></ul><ul><ul><li>“Members shall pro...
MED in UK Law (1)  <ul><li>-  Revised EU Medical Exposures Directive (97/43/Euratom): UK  Ionising Radiations Regulations ...
MED in UK Law (2)  <ul><li>Revised EU Medical Exposures Directive (97/43/Euratom) : Ionising Radiation(Medical Exposure)Re...
MED in UK Law (3)  <ul><li>UK Department of Health : </li></ul><ul><ul><li>Hospitals can adopt national DRLs for use local...
Diagnostic Reference Levels  <ul><li>A guide to the – indistinct – border between good / normal practice and bad / abnorma...
<ul><li>Most easily understood at National  i.e. – very large sample – level </li></ul><ul><li>75 th  percentile chosen as...
Skull Chest T Spine L spine Abdomen Pelvis Bitewing L Ob Breast UK National Diagnostic Reference Levels 2007 Ba Swallow Ba...
Variation of National DRL with time -  Ba Enema : 75 th  percentile threshold 1984 -2005 1984 2005
DoH Guidance April 2007  <ul><li>“An employer may decide to adopt National DRLs or to set higher OR lower DRLs depending o...
Local Diagnostic Reference Levels  DoH Guidance April 2007   <ul><li>By taking responsibility for establishing and setting...
DRLs The first step <ul><li>You must have a dose monitoring programme in place </li></ul><ul><li>Your dose monitoring prog...
(The second step) <ul><li>IPEM Report 88 : Guidance on the establishment and use of Diagnostic Reference Levels for Medica...
Setting Local DRLs  -or- Choosing DRLs to set locally <ul><li>The establishment of Local DRLs is NOT a precise science. </...
Skull Chest T Spine L spine Abdomen Pelvis Bitewing L Ob Breast UK National Diagnostic Reference Levels 2007 Ba Swallow Ba...
How do you set Local DRLs <ul><li>Adopt  recognised reference / published  levels  </li></ul><ul><li>Adapt  the actual val...
NDRL/ : LDRL A guide to the rather indistinct borderline between ‘good and normal practice’ and  ‘bad and abnormal practic...
Or use your own data to set  Local DRLs <ul><li>One way of doing this is to set a Local DRL as the mean of the distributio...
Criteria for inclusion (1) <ul><li>Examinations must be performed reasonably frequently in the hospital /  department </li...
Criteria for inclusion (2) <ul><li>Ideally include at least one examination performed on each item of equipment that makes...
Criteria for inclusion (3) <ul><li>Ideally cover the work of all groups of operators carrying out radiological procedures,...
<ul><li>Choose examinations that typify the work of the hospital   </li></ul><ul><li>Don’t include more than you have to <...
-The Audit Spiral
How do you audit against  DRLs
How do you audit against  DRLs  <ul><li>If a DRL is consistently exceeded, you need to investigate why that is. What is me...
What do we mean by “greater than” <ul><li>If the  mean  dose exceeds the local DRL by more than a defined proportion (e.g....
What if your doses exceed the drl? ? <ul><li>The outcome of an investigation will be to identify why the DRL has been exce...
What are the most likely factors to consider if a  DRL is consistently exceeded? <ul><li>Measurement Methodology </li></ul...
Outcome of investigation <ul><li>Identify why DRL exceeded </li></ul><ul><li>Identify remedial measures </li></ul><ul><ul>...
What does a DRL  do?  <ul><li>DRL only triggers the first step in the optimisation process. </li></ul><ul><li>But it is a ...
Balancing patient dose and image quality  <ul><li>Which examinations should form the focus of the optimisation effort?. </...
And Finally <ul><li>Diagnostic Image quality is the main concern </li></ul><ul><li>Don’t reduce dose so much that the imag...
THANK YOU FOR YOUR ATTENTION Ninewells Hospital & Medical School
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Sutton Leiden Presentation Dec 2008 Ds4

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Sutton Leiden Presentation Dec 2008 Ds4

  1. 1. Development of DRLs in the UK David Sutton Ninewells Hospital & Medical School Dundee, UK
  2. 2. Why have Diagnostic Reference Levels ? <ul><li>Radiation is harmful </li></ul><ul><li>Diagnosis is beneficial </li></ul><ul><li>Need to use the smallest amount of radiation which will result in the correct diagnosis. </li></ul>
  3. 3. Perceived image quality is task and reader dependent.
  4. 4. Radiologist A Radiologist B
  5. 5. <ul><ul><li>What dose is just low enough </li></ul></ul><ul><ul><li>& what image quality is just good enough </li></ul></ul><ul><ul><li>to achieve the required diagnosis? </li></ul></ul>Why have Diagnostic Reference Levels ?
  6. 6. <ul><ul><li>It’s easier to decide that if the majority of radiologists agree that a particular dose range results in images that are diagnostic then they probably are. </li></ul></ul>Why have Diagnostic Reference Levels ?
  7. 7. What is a Diagnostic Reference Level ? <ul><li>A dose level for typical examinations for groups of standard-sized patients or standard phantoms and for broadly defined types of equipment </li></ul><ul><li>A guide to the – indistinct – border between good / normal practice and bad / abnormal practice. </li></ul>
  8. 8. What is a Diagnostic Reference Level ? <ul><li>A level set using an arbitrary (i.e. not scientific) threshold in a distribution </li></ul><ul><li>A trigger for the first step in the optimisation process </li></ul>‘
  9. 9. Historical Perspective
  10. 10. Historical Perspective – What is diagnostic? UK Survey of Patient Dose 1983-5 20 Hospitals 5 37 Pelvis AP 8 88 Abdomen AP 11 71 L Spine AP 4 43 T Spine AP 11 48 Chest PA 5 19 Skull AP Room Ratio Patient Ratio Examination
  11. 11. UK Survey of Patient Dose 1983-5
  12. 12. RCR “Patient Dose Reduction in Diagnostic Radiology 1990” <ul><li>“Some 1300 man Sv could be saved by persuading the 25% of hospitals with the higher doses for the six exams to change their technique to fall in line with the remaining 75%” </li></ul>
  13. 13. ICRP 60 1991 <ul><li>Consideration should be given to the use of dose constraints or investigation levels selected by the appropriate professional or regulatory agency for application in some common diagnostic procedures. </li></ul>
  14. 14. 1992 – UK National Protocol <ul><li>Practical guidance on comparing local performance with National Practice </li></ul><ul><li>Local performance to be assessed in terms of mean dose in a representative sample of standard sized patients. </li></ul><ul><li>Not a legal requirement. </li></ul>
  15. 15. Doses to patients from medical x-ray examinations in the UK – 1995 review <ul><li>50 000 patient dose measurements </li></ul><ul><li>375 UK hospitals </li></ul><ul><li>Average 30% reduction in mean doses for common x-ray exams since 1984 </li></ul>
  16. 18. NRPB 2000 Review of Patient Doses
  17. 19. NRPB 2000 Review of Patient Doses
  18. 20. Revised EU Medical Exposures Directive (97/43/Euratom) : MED <ul><li>Article 4(2) </li></ul><ul><ul><li>“Members shall promote the establishment and use of diagnostic reference levels for diagnostic examinations in radiology and nuclear medicine and the availability of guidance for this purpose (having regard to European diagnostic reference levels where available)” </li></ul></ul>
  19. 21. MED in UK Law (1) <ul><li>- Revised EU Medical Exposures Directive (97/43/Euratom): UK Ionising Radiations Regulations 1999 </li></ul><ul><li>- Suitable quality assurance programmes for medical imaging equipment should be implemented and should include measurements at suitable intervals to enable the assessment of representative patient doses </li></ul>
  20. 22. MED in UK Law (2) <ul><li>Revised EU Medical Exposures Directive (97/43/Euratom) : Ionising Radiation(Medical Exposure)Regulations 2000 </li></ul><ul><ul><li>Hospital needs to establish DRLs and </li></ul></ul><ul><ul><li>Undertake appropriate reviews when DRLs are consistently exceeded and </li></ul></ul><ul><ul><li>Ensure that corrective action is taken where appropriate. </li></ul></ul>
  21. 23. MED in UK Law (3) <ul><li>UK Department of Health : </li></ul><ul><ul><li>Hospitals can adopt national DRLs for use locally or establish their own based on local practice, if sufficient local data are available </li></ul></ul><ul><ul><li>Quite clear that local DRLs can be established </li></ul></ul>
  22. 24. Diagnostic Reference Levels <ul><li>A guide to the – indistinct – border between good / normal practice and bad / abnormal practice. </li></ul><ul><li>Based on the premise that images are diagnostic in the first place . </li></ul>
  23. 25. <ul><li>Most easily understood at National i.e. – very large sample – level </li></ul><ul><li>75 th percentile chosen as the ‘indistinct border” – No real scientific basis </li></ul>National Diagnostic Reference Levels
  24. 26. Skull Chest T Spine L spine Abdomen Pelvis Bitewing L Ob Breast UK National Diagnostic Reference Levels 2007 Ba Swallow Ba Meal Ba Enema IVU MCU Pyelography Coronary Angio Venography etc CT Head CT Chest CT Abdomen CT CA ChestAbdoPelvis (Paediatric CT and complete exams)
  25. 27. Variation of National DRL with time - Ba Enema : 75 th percentile threshold 1984 -2005 1984 2005
  26. 28. DoH Guidance April 2007 <ul><li>“An employer may decide to adopt National DRLs or to set higher OR lower DRLs depending on the imaging equipment available to them or the patient case mix of the healthcare establishment. </li></ul><ul><li>Local DRLs higher than those set nationally would need to be justified” </li></ul>
  27. 29. Local Diagnostic Reference Levels DoH Guidance April 2007 <ul><li>By taking responsibility for establishing and setting their own DRLs, hospitals (or groups of hospitals) should have the ability to adapt local practice and more effectively optimise exposures. </li></ul>
  28. 30. DRLs The first step <ul><li>You must have a dose monitoring programme in place </li></ul><ul><li>Your dose monitoring programme needn’t just measure dosimetric quantities such as esd, dlp or kap – although preferable. </li></ul><ul><li>Example : screening time during pacemaker insertion. </li></ul>
  29. 31. (The second step) <ul><li>IPEM Report 88 : Guidance on the establishment and use of Diagnostic Reference Levels for Medical X-Ray Examinations. </li></ul>
  30. 32. Setting Local DRLs -or- Choosing DRLs to set locally <ul><li>The establishment of Local DRLs is NOT a precise science. </li></ul><ul><li>You need simple and practical methods to set them. </li></ul><ul><li>You need simple and practical methods to audit them. </li></ul><ul><li>And you don’t need to measure everything! – Typical or representative examinations. </li></ul>
  31. 33. Skull Chest T Spine L spine Abdomen Pelvis Bitewing L Ob Breast UK National Diagnostic Reference Levels 2007 Ba Swallow Ba Meal Ba Enema IVU MCU Pyelography Coronary Angio Venography etc CT Head CT Chest CT Abdomen CT CA ChestAbdoPelvis (Paediatric CT and complete exams)
  32. 34. How do you set Local DRLs <ul><li>Adopt recognised reference / published levels </li></ul><ul><li>Adapt the actual values (potentially downwards) to your own practice . </li></ul>
  33. 35. NDRL/ : LDRL A guide to the rather indistinct borderline between ‘good and normal practice’ and ‘bad and abnormal practice’ Local DRL NDRL
  34. 36. Or use your own data to set Local DRLs <ul><li>One way of doing this is to set a Local DRL as the mean of the distribution of mean room doses that you measure. </li></ul><ul><li>This is OK even if you only have one room. In this case you are monitoring the variation of mean room dose with time. </li></ul>
  35. 37. Criteria for inclusion (1) <ul><li>Examinations must be performed reasonably frequently in the hospital / department </li></ul><ul><li>Data collection must be feasible </li></ul>
  36. 38. Criteria for inclusion (2) <ul><li>Ideally include at least one examination performed on each item of equipment that makes a significant contribution to the workload of the department </li></ul>
  37. 39. Criteria for inclusion (3) <ul><li>Ideally cover the work of all groups of operators carrying out radiological procedures, e.g. - </li></ul><ul><ul><li>Radiographers / technologists </li></ul></ul><ul><ul><li>radiologists </li></ul></ul><ul><ul><li>non-radiological clinicians </li></ul></ul>
  38. 40. <ul><li>Choose examinations that typify the work of the hospital </li></ul><ul><li>Don’t include more than you have to </li></ul>Setting DRLs in your hospital <ul><li>Don’t forget to audit & review them (i.e.close the audit loop) </li></ul>
  39. 41. -The Audit Spiral
  40. 42. How do you audit against DRLs
  41. 43. How do you audit against DRLs <ul><li>If a DRL is consistently exceeded, you need to investigate why that is. What is meant by “consistently”. </li></ul><ul><li>One way assumes that a set of measured patient doses would be considered to be consistently above a DRL if their average was greater than the DRL. Then the problem becomes one of defining what is meant by ‘greater’. </li></ul>
  42. 44. What do we mean by “greater than” <ul><li>If the mean dose exceeds the local DRL by more than a defined proportion (e.g. 20%) and by at least 2 times the standard error of the mean of the local measurement then an investigation is required as to why the DRL has been exceeded. </li></ul>
  43. 45. What if your doses exceed the drl? ? <ul><li>The outcome of an investigation will be to identify why the DRL has been exceeded. </li></ul><ul><li>Remedial measures should be identified and, where possible, acted upon prior to recommencing the dose audit cycle. </li></ul>
  44. 46. What are the most likely factors to consider if a DRL is consistently exceeded? <ul><li>Measurement Methodology </li></ul><ul><li>Case Mix </li></ul><ul><li>Equipment </li></ul><ul><li>Technique </li></ul>
  45. 47. Outcome of investigation <ul><li>Identify why DRL exceeded </li></ul><ul><li>Identify remedial measures </li></ul><ul><ul><li>Investigate ways of reducing doses </li></ul></ul><ul><ul><li>Equipment factors </li></ul></ul><ul><ul><li>Technique change </li></ul></ul><ul><li>Act, prior to recommencing audit cycle. </li></ul>
  46. 48. What does a DRL do? <ul><li>DRL only triggers the first step in the optimisation process. </li></ul><ul><li>But it is a trigger that may tell you where to look and where to prioritise your effort. </li></ul>
  47. 49. Balancing patient dose and image quality <ul><li>Which examinations should form the focus of the optimisation effort?. </li></ul><ul><li>How do we prioritise ? </li></ul>
  48. 50. And Finally <ul><li>Diagnostic Image quality is the main concern </li></ul><ul><li>Don’t reduce dose so much that the images become non diagnostic – dose reduction is NOT a holy grail </li></ul><ul><li>Many dose savings can be made without affecting the image at all </li></ul>
  49. 51. THANK YOU FOR YOUR ATTENTION Ninewells Hospital & Medical School

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