1. European Diagnostic Reference Levels in Paediatric Imaging
Stephen Evans, Head of Medical Physics, Northampton General Hospital, UK
EFOMP Officer, Chair Projects

2. “Children are at a much higher risk compared to adults from developing cancer”

3. It’s not child’s play UNSCEAR (2010) estimates
250 million paediatric radiological examinations (including dental) per annum worldwide
Children may receive substantial radiation doses
in early life
life-threatening disease
Children may develop
childhood leukaemia
breast cancer or
thyroid cancer

4. It’s not child’s play Children need special attention:
diseases specific to childhood
additional risks
Children need special care:
provided by parents and carers
from specially trained personnel
Justification and optimization principles are even more important for children

5. 2013

6. Why so high ? Higher sensitivity to radiation Longer life expectancy
Paediatric doses will exceed adult doses if the same exposure settings are used

7. Paediatric effective dose and risk
Examination
Effective dose (mSv)
Lifetime risk of fatal cancer
Limbs
<0.005
1/few million
Chest (PA)
0.01
1/million
Spine (AP, PA, Lat)
0.07
1/150,000
Pelvis
0.08
1/120,000
AXR
0.10
1/100,000
CT Head 2
1/5,000
CT Body 10
1/1,000 ?
Twice the adult risk
i.e. 10% per Sv.
Cook JV, Imaging, 13 (2001), Number 4

8. Paediatric risk
CHILD
ADULT
Is this sensitive enough?

9. Risk from single CT exam
Not
1 in 1000
1 in 1000
Not
1 in 5000
Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric CT David J. Brenner1, Carl D. Elliston1, Eric J. Hall1 and Walter E. Berdon2,AJR February 2001, Volume 176, Number 2 Read More:

10. What’s the main issue? Estimated about
85% paediatric dose from CT, interventional fluoroscopy and cardiac nuclear medicine
15% paediatric dose from radiography and general fluoroscopy

11. So what have we done about it?

12. Well, we have our Directives…

13. COUNCIL DIRECTIVE 2013/59/EURATOM of 5 December laying down basic safety standards for protection against the dangers arising from exposure to ionising radiation, and repealing Directives 89/618/Euratom, 90/641/Euratom, 96/29/Euratom, 97/43/Euratom and 2003/122/Euratom
(28) …important technological and scientific developments have led to a notable increase in the exposure of patients. …Directive should emphasise the need for justification of medical exposure, … the use of diagnostic reference levels and the availability of dose-indicating devices.

14. COUNCIL DIRECTIVE 2013/59/EURATOM
Art 4 (20) "diagnostic reference levels" means dose levels in medical radiodiagnostic or interventional radiology practices, or, in the case of radio-pharmaceuticals, levels of activity, for typical examinations for groups of standard-sized patients or standard phantoms for broadly defined types of equipment;
Art 22 (iii) where practicable, specific diagnostic reference levels are put in place;
Art Member States shall ensure the establishment, regular review and use of diagnostic reference levels for radiodiagnostic examinations, having regard to the recommended European diagnostic reference levels where available, and where appropriate, for interventional radiology procedures, and the availability of guidance for this purpose.
Art 58 (f) appropriate local reviews are undertaken whenever diagnostic reference levels are consistently exceeded and that appropriate corrective action is taken without undue delay.
Art 53 MPE (a) optimisation of the radiation protection of patients and other individuals subject to medical exposure, including the application and use of diagnostic reference levels;

15. And, we have many many scientific studies and Reports…

16. DRLs typically range x1.5 to upto x7

17. What does all this mean?

18. 1996

19. EUR 16261, 1996
used the 3rd quartile entrance-surface-dose for a standard five-year old child as the reference dose for all paediatric patients

20. EUR 16261, 1996 Good general principles Patient identification!
Quality control of x-ray system
Use of low attenuation materials
Immobilisation
Field size limitation
Good knowledge of paediatric anatomy
Protective shielding
Gonads, breast
Radiographic exposure factors
Number of exposures
NEVER EVENT
DRLs
Good Radiographic Practice
JUSTIFICATION

21. Conclusions of EUR 16261
Every effort should be made to reduce doses for children less than 5 years of age to below the values presented
Strict adherence to all the radiographic technique factors recommended can lead to significant dose reduction
X-ray generators employed in paediatric examinations should be capable of selecting the low mAs values required to ensure that the recommended kV values can be employed

22. 1999

23. "Guidance on diagnostic reference levels DRLs for medical exposure", European Commission Radiation Protection 109 (RP 109), 1999)
exposures requiring the most attention and are of the most importance for the establishment of DRLs are the high-dose medical examinations, especially computed tomography (CT) and interventional procedures (IR)

24. RP 109
“DRLs should be set by Member States …………….. harmonised levels might be feasible and are certainly preferable.”

25. RP-109 - Factors affecting dose
Equipment factors
inappropriate exposure protocols
deterioration of the image chain
Human factors
inattention, indifference or too much work pressure
individual reluctance to accept generally-accepted standard procedures

26. DRLs in practice DRLs can be assessed using:
entrance surface doses, measured with TLD, or
DAP [Gy.cm2]
DAP is more practical because
(i) the whole examination is recorded;
(ii) the position of the patient in the beam is less important
(iii) there is no need to disturb the patient
For CT
Dose Length Product (DLP)

27. DAP DRL issues Disadvantages using DAP
absorbed organ dose needs to be measured
not always a fixed relationship between the DAP and the absorbed dose
where small areas are exposed,
the DAP can be low while the absorbed dose is high
when a large area is exposed,
the DAP can be high but the absorbed dose low
the field size is often changed during fluoroscopy procedure

28. CT DRL issues Disadvantages of using DLP
DLP = scan length (cm) x CTDIvol (mGy)
Depends on height of patient
Equipment characteristics
iterative reconstruction -50%
AEC variable mAs – ?%
might be set too high
dose could be more

29. DLP - Dose

30. Alliance for Radiation Safety in Pediatric Imaging
“Image Gently”
“One size does not fit all...so when we image, let's image gently!“
Alliance for Radiation Safety in Pediatric Imaging 

32. IAEA No. 24, 2013
“… standardized methodologies to determine paediatric dose for all major modalities, such as general radiography, fluoroscopy and computed tomography.” “children can receive doses in excess of those delivered to Adults”

33. IAEA No. 24, 2013 5y old 5y old Weight? Height? 25 kg 115 cm to to
CENTRE FOR DISEASE CONTROL AND PREVENTION, 2000 CDC Growth Charts for the United States: Methods and Development, Vital and Health Statistics, Department of Health and Human Services, Rep. (PHS) , Hyattsville, MD (2002).

34. IAEA No. 24 – Patient size Options Age (v. Poor) Patient thickness
good for projection radiography
not so good for CT
how to measure?
Equivalent Cylindrical Diameter (ECD)
W is weight in gms and H is height
in cm

35. Equivalent Cylindrical Diameter
H2O
H2O
ECD
ECD

36. 2011

37. Size-Specific Dose Estimate - SSDE
CTDIvol for 32 or 16 diameter phantom
SSDE = f32/16 x x CTDIvol
x depends on projection

39. Effective Diameter
Circle of same area A A AP
LAT

40. SSDE
Effective diameter for typical 5 year old = 18.5 cm Conversion Factor for 5 year old (32 cm phantom) ~ 1.9 This means for a given CTDIvol the dose will be twice as much for a typical 5 year old compared to an adult. Q: Can these factors be used to define the required exposure conditions or do we need equivalent cylindrical diameter ?

41. Interventional Fluoroscopy
Equipment should be appropriately designed. Consider:
Beam filter
Beam area
Minimum tube currents
Reduced exposure pulse (need fast for heart)
Removal of the anti-scatter grid
Decreased magnification
Appropriate exposure levels - programming
RIS – PACS, Repeat procedures
Any repeat exposure within the last 60 days should be considered additive

42. Fluoroscopy What DRLs do we need? Incident air kerma Ki (mGy)
Ki = Y(d)Pit(d/dFSD) Y(d) – output at distance d
Pit -- tube loading (mAs)
dFSD – focus to skin distance
Entrance Surface Air Kerma (ESAK) Ke (mGy)
Ke = Ki.B (Backscatter factor)
Kerma-area-product (PKA) (mGy.cm2)
KAP or DAP meter
IAEA No. 24

43. Possibilities DAP ? Field size varies
Is it possible to have DRLs for fluoroscopy?
Probably yes
Skin dose ?
Would not expect for small patients to be high
Obese older patients!!
DAP ?
Field size varies
Sometime bigger (field) is better (visualisation)
Monitor fluoroscopy exposure time + acquisitions runs (images) per procedure ?
May be our best indicator for Optimised systems!
TIME – Timely Intervention of Monitored Event

44. DRLs DRLs show what should be possible
encourage changes in working procedures
Need to be tailored or take account of
Equipment performance
Patient demographics

45. So what more do we need to do?
Identify Equipment factors
Sort out Human factors
Extend the range of DRLs
Base DRLs on individuals
do we use Equivalent Cylindrical Diameter ? or
effective diameter ? or
something else ?
Base DRLs on individuals
Planar CT Floro ?
DAP DLP TIME E E o

46. So what are we going to do?

48. PiDRL - consortium European Society of Radiology, ESR
European Society of Paediatric Radiology, ESPR 
European Federation of Radiographer Societies, EFRS
European Federation of Organisations for Medical Physics, EFOMP
Finnish Radiation and Nuclear Safety Authority, STUK with two sub-contractors:
Helsinki University Hospital, HUS, and
Public Research Centre Henri Tudor

49. PiDRL - objectives
Agree on a methodology for establishing and using DRLs for paediatric imaging, and
Update and extend the European DRLs to cover more procedures and a wider patient age / weight range.

50. PiDRL – Work packages
WP0 - management and general coordination of the project
WP1 - methodology for DRLs, and producing European guidelines
WP2 updating and extending the existing European DRLs
WP 3 organize the European workshop

51. THE END It’s TIME for a change
Diagnostic procedures saves children’s lives
the effects of radiation lasts their lifetime
but remember
We all have a duty as professionals
to make it safer for the children
It’s TIME for a change

52. ICRP Publication 117