|Section 6 – Medical exposure of patients
This chapter has not been developed very much since the previous draft. It is regrettable that the impending ICRP Committee 3 report on medical exposures is not yet available. No doubt, further development of ICRP’s recommendations regarding medical exposure will take place once it is.
As in the previous draft (2005), there appear to be no fundamental changes in the recommendations for protecting people from medical exposures compared to those in ICRP60, ICRP62 and ICRP73. Much of this section is still verbatim extracts from ICRP73 but they do not follow a logical order and are a confusing mixture of advice on how patient, public and occupational exposures from medical sources of radiation should be controlled. It would be better if the chapter started with a clear description of what types of exposed individual the term ‘medical exposure of patients’ is meant to include. Simply adding “of patients” to the chapter title has led to further confusion, since it still appears to include individuals who are not being exposed as part of their own diagnosis or treatment (i.e. ‘comforters and carers’, ‘volunteers in biomedical research’ and ‘individuals undergoing medico-legal exposures’). A brief review of the special ways in which the principles of justification and optimisation are to be applied to ‘patients’ could then form the bulk of Section 6, with supplementary sections dealing with the special considerations for ‘comforters and carers’, ‘volunteers in biomedical research’ and ‘individuals undergoing medico-legal exposures’.
The recommended use of generic justification in the absence of individual justification in some circumstances is a departure from the approach adopted in the European Medical Exposure Directive and contrary to the approach in all other medical practices where the needs of the individual patient are paramount.
The recommendations regarding medical exposures have concentrated heavily on diagnostic x-ray procedures with insufficient attention paid to other uses of ionising radiation in medicine (e.g. nuclear medicine and radiotherapy).
Little attention is given to medical exposures in the other chapters of these draft recommendations where general principles of radiation protection and dosimetry are discussed. This is despite their importance as one of the major sources of ‘controllable’ population exposure.
Paragraph 244 – in the 1st sentence: Insert “… by prescribing generic dose limits” after “the limitation of the dose to the individual patient”
2nd sentence: Add to end of sentence – “and on optimisation of protection.” (as in paragraph 172). Rest of paragraph - why are occupational and public exposures mentioned here?
Paragraph 245 - the three issues raised in this paragraph (’Secondly’, ‘Thirdly’ and ‘Finally’) appear to be totally unrelated to each other and the last one has nothing to do with ‘medical exposures’. The reader is left wondering what this apparently random list of issues has to do with ICRP’s recommendations on how medical exposures of patients should be controlled.
Paragraph 246 - “Procedures” would be better than “processes” in the 1st sentence and it is not only the “physicians” that need training but also the technicians (radiographers) that carry out and directly control most of the exposures. It is not clear why the need for training is dependent upon the fact that patient exposures are deliberate. If they were unintentional, there would surely be even more urgent need for training. Surely radiation exposures in medicine are limited by regulatory processes in all those countries that have national regulations dealing with radiation protection of patients. There are no dose limits for medical exposures, but there is regulatory control.
Paragraph 247 - as in paragraph 191, it is not clear whether ICRP intends that the generic justification of a specified radiological procedure and the justification of each individual patient exposure should be applied to all medical exposures of patients or whether there are situations in which only one of them needs to be applied. Clarification of this point should not be left until paragraph 250 (see comment on paragraph 250, below).
4th sentence: Is not the ultimate aim of generic justification to judge that the benefits will usually outweigh the risks, rather than to merely judge that the procedure will usually be of some good, without any consideration of the risks?
5th sentence: Why leave it to this second level of justification before you have to demonstrate more good than harm?
Paragraph 248 - it is not clear what is meant by ‘This procedure’ in the first line – does it refer to the radiological procedure itself or the process of individual justification as described in the preceding paragraph? In addition, the second sentence seems to relate to justification issues for diagnostic exposures, but optimisation issues in therapy.
Paragraph 250 - two levels of justification, generic and individual, were identified in paragraph 247. This paragraph implies that individual justification is only important in ‘complex’ diagnostic and therapeutic procedures and not needed for ‘simple’ diagnostic procedures. This is not consistent with the EC Medical Exposure Directive 97/43/Euratom, which requires that ‘all individual medical exposures shall be justified in advance taking into account the specific objectives of the exposure and the characteristics of the individual involved’ [Art 3 (1)(b)] and which is legally binding for European Member states. It is also contrary to the approach adopted in all other medical practices where the needs of the individual patient are paramount.
The requirement for the individual justification of all medical exposures of patients must be made clear in these recommendations. ‘Generic justification’ of a radiological procedure at the national level by national professional and regulatory bodies (as discussed in paragraph 249) should be additional to and not instead of ‘individual justification’.
It is not clear what is meant by a 'complex diagnostic procedure' (would this include, for example, CT scanning or cardiology procedures) and what about interventional procedures?
Paragraph 251 – change to – “..and consequently somewhat less attention has been given by ICRP to optimisation of...” . Considerable attention has been given by others to the optimisation of medical exposures in recent years.
Paragraph 252 - this paragraph should clearly say that diagnostic reference levels are not a form of ‘dose constraint’ as defined by ICRP for occupational and public exposures.
Paragraph 254 - 1st sentence: Change to – “Diagnostic reference levels apply to medical exposures of patients for diagnostic purposes and not for therapeutic purposes nor to occupational and public exposures from medical radiology.’ In the European Medical Exposure Directive DRLs are defined as for use in ‘medical radiodiagnostic practices’, which are taken to exclude interventional radiology. ICRP might wish to consider and recommend whether DRLs also have a use in interventional radiology.
Paragraph 255 - 1st sentence: Insert “levels” after “reference” and delete “or low” after “are unusually high”. The way in which DRLs are currently set by appropriate national bodies does not indicate when doses are unusually low.
3rd sentence: The diagnostic reference level should surely ‘be expressed as a readily measurable patient dose related quantity’? There are many readily measurable patient-related quantities that are totally unsuitable (e.g. height, weight or inside-leg measurement).
Paragraph 256 - now that DRLs have been established and used in a number of countries for many common types of x-ray examination and most common nuclear medicine procedures, is it still valid to say that “a multiplicity of levels will reduce their usefulness”?
Replace “therapeutic” with “radiotherapy” in second sentence.
The use of reference levels for radiotherapy procedures is dismissed out of hand. Is there not a case for investigating their suitability for helping to optimise the doses to healthy tissues surrounding the treatment volume?
Paragraphs 257-258 - are these paragraphs relevant for a section on DRLs?
Paragraph 260 - what about the risks of cancer induction following prenatal exposures (see paragraph 80)?
Paragraphs 261-262 - whilst the risk of potential harm to a fetus is usually less from those exposures carried out for a diagnostic purpose rather than a therapeutic one, there are still a number of diagnostic procedures where the possibility of pregnancy should be established beforehand. The statement in paragraph 262 regarding the importance of ascertaining pregnancy in a patient prior to radiotherapy implies it may not be important in other areas. Whilst the diagnostic procedure may be medically indicated for the mother, if pregnancy is known steps can be taken to further optimise the dose associated with the procedure and therefore reduce any dose to the fetus. In addition, certain interventional or guiding procedures may deliver a high dose to patient and fetus and these do not seem to be addressed in this section.
Paragraph 263 - add to end of last sentence – “..and the consequent risks of harm to the developing fetus and of cancer in later life.”
Paragraph 265 – suggest that this is deleted as it is repeated in paragraph 266.
Paragraph 266 – HPA-RPD welcomes the recognition that constraints should not be applied rigidly, especially for the treatment of very sick children. The definition in the first sentence should also appear at the beginning of section 6. In the final sentence, should it not be ‘limit’ rather than ‘constraint’?
Paragraph 267- heading should be numbered “6.5”. This is not part of section 6.4. 2nd sentence: Change “radio-elements” to “radionuclides”.
Paragraph 269 - heading should be numbered “6.6”. This paragraph refers only to those exposures carried out for insurance purposes. It is not clear if this is intended to serve as an example or if it is the only type of medico-legal exposure recognised by the ICRP. In the UK, medico-legal exposures are considered to include several other groups of exposures such as chest radiographs for emigration purposes or skeletal surveys to establish evidence of non-accidental injury (either on an injured child or in some cases, its siblings also). An international meeting held in Europe in 2002 demonstrated the variety and breadth of approaches that other countries have in defining medico-legal exposures. Does the ICRP intend this statement regarding the inapplicability of public dose constraints to apply to other examples of medico-legal exposures?
Paragraph 270 - heading should be numbered “6.7”.
Paragraph 271 - the first two sentences do not appear to be related to the release of patients after radiotherapy.
Paragraph 273 - on line 2, clarify that ‘controlled’ means dose limits for the public and dose constraints for comforters and carers.
Amend end of first sentence to ‘although the risk of cancer induction due to the doses received from these patients …’.
Amend third sentence to ‘contamination with radioiodine’.
The meaning of the final sentence is unclear.
Paragraph 276 - which recommendations – these or ICRP 94, or both?