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Submitted by Shane Foley, EFRS - European Federation of Radiographer Societies
   Commenting on behalf of the organisation
Document Diagnostic Reference Levels in Medical Imaging
 
Overall, very good document and the steps provided for investigating excessive doses is very beneficial and practical way.

 

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4o) correct grammar ‘from at several different health facilities’

 

 

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4o) Values of DRL quantities from patient examinations are collected from at several different health facilities – Please DEFINE several. Is the intention here to include a specific minimum number of centres nationally to ensure data can be appropriately extrapolated?

 

 

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4o) The 75th percentile value of the distribution of median values (the 50th percentile) of a DRL quantity at healthcare facilities throughout a country is used as the ‘national DRL’.

 

How representative should these facilities be - any advice? Later on mention is made of collecting from large / medium size facilities – perhaps elaborate here. Why are small facilities omitted when often practice in these centres may not be as optimised.

 

 

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4p) When national DRL values exist for many or most countries within a region (e.g. the European Union), regional DRL values may be determined by using the median value of the available national DRL values – DEFINE many or most – PIDRL project has stated a minimum of three countries to allow flexibility for examinations where data (eg paediatric interventional exams) is limited. Can a similar minimum number be recommended?

 

 

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4r) apparent that further optimisation is being achieved locally, ‘Local DRLs’ based on surveys  within that limited area might be introduced to further assist the optimisation process. One example of their use is to account for the substantial dose reduction that could be achieved through the introduction of digital radiography detectors into dental radiography. Another example is the introduction of new methods for post-processing of images. Should local DRLs also be used and more appropriate when local dose values are higher than the national DRL – when justified eg for a tertiary referral centre with more complex case load or perhaps with centres with old equipment who cannot possibly reduce their doses in line with the DRL without a large capital investment

 

 

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Correct grammar ‘Values DRL quantities’

 

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35: the median value to be used as a low dose indicator. Surely this is out of step with the current DRL level which is set at the 75th percentile. Surely if looking for excessively low dose exams impacting on image quality the lower level should be at the 25th percentile, otherwise 50% of the distribution will need to examine their image quality first.

 

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No justification given as to the inclusion of larger or medium size centres for data collection other that they should have a sufficient workload. This could be problematic if smaller centres are not included with possibly more out dated equipment and thus if their data does not contribute to the national DRL value they could be well in excess of the values and unable to reduce as are not in a position to replace technology immediately SEE POINT 77

 

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No justification given as to the recommended sample sizes for data collection – preferably 20 patients, 30 for fluoroscopy and 50 for mammography

 

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There should be standardisation of weight – but how! These needs guidance

 

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The median (the 50th percentile) of the distribution used to set the national DRL may also be used as an additional tool for optimisation – this is conflicting as on the one hand the commission are recommending its use as an Achieveable Dose but on the other stating that below this level image quality needs to be investigated as it could be affected!

 

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Spelling of examinations!

 

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When DRLs exist for many or most – this should be defined further with perhaps a minimum number suggested

 

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In some countries, hospitals or health authorities may set their own local DRLs. These will ideally be based on national values, but can be adjusted to apply to local practices to encourage further optimisation. They can also be used to set lower values for new technologies that allow lower dose levels to be achieved – surely local DRLs should be allowed to be higher also where appropriate and justified, perhaps due to local technology or case mix? This is addressed later on in the document

 

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90: For CT, it is particularly important that appropriately trained medical physicists are involved to provide advice on the optimisation of protection. WHY not also include trained / specialised radiographers as they have important practical experience and knowledge of equipment optimisation.

 

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For fluoroscopy and CT, all of the quantities listed should be recorded if  they are available

 

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If Chest XR examination is to be included, should different DRLs be set for different projections / technique, e.g. PA vs AP vs Mobile??

 

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The term Detector Dose index is inconsistent with recent AAPM and IEC terminology which uses the term Exposure Index

 

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The proposal to have Dg as a DRL quantity for mammography neglects the fact that DRLs should be based on quantities that are easily measured (ICRP, 2007) – given that calculations have to be performed. Suggest this as an alternative quantity only, otherwise it may take from the use of DRLs in mammography

 

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On what basis is the recommendation for a minimum of 30 patients required for CT DRLs using manual paper based surveys? Please provide reference or clarify

 

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Weight bands are recommended for paediatrics in 10kg categories. On what basis is this recommendation made given the non linear growth of paediatrics. Please see the PiDRL recommended weight bands and perhaps seek consensus from both bodies.

 

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Age ranges for paediatric patients is listed but only up to 16 years of age, when paediatrics  are up to 18 years as defined by the WHO!!

 

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On what basis are the paediatric age ranges listed? It appears they are used on the basis of previous and commonly used categories but this has no scientific rationale. Can consensus be achieved with the EU PiDRL project recommendations who used actual clinical data to base their age / weight ranges on?

 

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The short exposures times used for paediatrics means that manual exposures are often used instead of AEC – BUT in fact this is also due to the fact that paediatric body parts are often too small to fully cover an AEC chamber in its entirety, which may result in an underexposure!! Suggest including this clarifying point also

 

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The recommendation for 7 different weight groupings for paediatrics seems excessive and will make the practical establishment and use of DRLs difficult given the paucity of patient numbers esp for less frequent examinations (eg CT, interventional) where DRLs are crucial for optimisation

 

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Please define what ‘consistently exceeded’ means. If a median local dose value exceeds a DRL once – does this constitute consistently exceeded or does this imply that more than one analysis has to be performed?