3.2 System and Legislative Framework forRadiationProtection
3.2.1 ICRP System ofRadiationProtection
The system of radiationprotection that is used across Europe and worldwide is based onthe recommendations of: the International Commission forRadiation Protection (ICRP); and the International Commission onRadiation Units and Measurements (ICRU). The conceptualframework adopted by the ICRP in its publication ICRP 60 (ICRP1991) is one of a System of RadiologicalProtection and builds on the System of Dose Limitation centralto earlier ICRP documents such as ICRP 26 (ICRP 1977). ICRPpublication 60 (ICRP 1991) was substantially revised and updatedin 2007 with the publication of ICRP 103 (ICRP 2007).
The ICRP system ofradiation protection isbased on three fundamental principles: justification,optimisation and dose limitation.
The principle of justification requires that any decision thatalters the radiationexposure situation should do more good than harm; in otherwords, the introduction of a radiation source should result insufficient individual or societal benefit to offset thedetriment it causes.
The principle of optimisation requires that the likelihood ofincurring exposures, the number of people exposed and themagnitude of their individual exposure should all be kept as lowas reasonably achievable, taking into account economic andsocietal factors. In addition, as part of the optimisationprocedure, the ICRP recommends that there should be restrictionon the doses to individuals from a particular source and thisleads to the concept of dose constraints.
The third principle of the ICRP’s system of protection is thatof dose limitation. This principle requires that the dose toindividuals from planned exposure situations, other than medicalexposure of patients, should not exceed the appropriate limitsrecommended by the Commission.
As part of the system of protection, ICRP publication 103defines three categories of exposure situations (ICRP 2007),namely: planned exposure situations which involve thedeliberate introduction and operation of sources; emergencyexposure situations, which require urgent action inorder to avoid or reduce undesirable consequences; andexisting exposure situations, which includeprolonged exposure situations after emergencies. By adoptingthis approach, in principle, the ICRP system of protectionshould be able to be applied to any situation ofradiation exposure,including that associated with security screening. Within theICRP system, security screening would be considered to be aplanned exposure.
The ICRP recognises three categories of exposed individuals:workers, patients and members of the public. These categories ofexposure are known as occupational, public and medical exposure.Occupational exposure is generally interpreted asradiation exposureof individuals as a result of their work. However, as radiationis ubiquitous, only those exposures that can reasonably beregarded as the responsibility of the operating management areincluded. Medical exposure is predominantly that of patients butalso includes exposures incurred by those caring for patients,other than as part of their occupation, and exposures incurredby volunteers as part of biomedical research programmes, wherethere is no direct benefit to the volunteer. Public exposurethen incorporates all exposures other than medical andoccupational.
The principles of justification and optimisation applyuniversally to all three categories of exposure situations(planned, emergency and existing), whereas dose limits applyonly to planned exposure situations. The exception to this isplanned exposure situations involving medical exposure wheredose limits do not apply. In the absence of a dose limit, doseconstraints assume a particular importance.
Dose constraints are used as part of the optimisation processfor planned exposures. They represent a level of individual dosewhich should not, in normal circumstances, be exceeded. They areused in the planning process and the chosen value will depend onthe circumstances of the exposure under consideration. They arenot a limit and do not represent a demarcation between safe anddangerous levels ofradiation exposure but areused, prospectively, as a tool for optimisation. For plannedexposures that have a dose limit associated with them, doseconstraints should be lower than the pertinent doselimit.
The term ‘practice’ was first introduced in 1991 in thepublication ICRP 60 (ICRP 1991) to distinguish between an activity that added doses and one thatreduced doses. The latter was known as an intervention. Whilethe ICRP in their more recent publication ICRP 103 (ICRP 2007)have moved to a situation-based approach, as outlined above,they still use the term ‘practice’ to denote an activity thatcauses an increase in exposure toradiation or in therisk of exposure to radiation. It is implicit in the concept ofa practice that the radiation sources that it introduces ormaintains can be controlled directly by action on the source. Itis understood, within the ICRP system of radiation ofprotection, that justification is a prior requirement of any newpractice.
Although the ICRP revised and updated their recommendations onradiationprotection in their 2007 document, ICRP 103, current Europeanlegislation is still based on the recommendations contained intheir earlier document, ICRP 60 (ICRP 1991).
3.2.2 Justification of practices
The justification of practices involving ionisingradiation prior totheir introduction into routine use must demonstrate economic,social or other benefits in relation to the health detrimentthey may cause. Depending on the type of practice underconsideration, this justification process can be complex and mayinvolve consideration of a wide range of societal and economicfactors, in addition to the potential dose detriment. Theconsequences to be considered are not confined to thoseassociated with radiation; they also include other risks as wellas the costs and benefits of the activity. Sometimes theradiation detriment will be a small part of all factorsconsidered and it is important that other types of detriment areconsidered. Similarly, benefit must be determined. Justificationtherefore goes far beyond the scope of radiologicalprotection.
Responsibility for judging the justification of new orexisting practices usually falls on nationalradiation protectionauthorities to ensure an overall benefit in the broadest senseto society although not necessarily to the individual. However,these authorities are likely to need input from otherstakeholders so that a fully informed decision can ultimately bemade in relation to justification. To search for the best of allthe available alternatives is a task beyond the responsibilityof radiological protection authorities (ICRP 2007).
Although the justification process considers the potentialbenefits and detriments to the exposed individual and tosociety, a practice may be considered to be justified even ifthere are no benefits to the individual provided the benefit tosociety is sufficiently strong. Application of the justificationprinciple to a new practice requires that no practice should beintroduced unless it produces sufficient net benefit to theexposed individual or to society to offset theradiation detrimentit causes. The justification may need to be re-examined as newinformation or technology becomes available.
This principle of balancing benefit and detriment is notunique to radiation safetybut while often the balancing is done implicitly, thejustification process will require an explicit demonstration ofa net benefit.
The fact that the doses arising from a practice may be wellbelow the public dose limit does not remove the requirement forjustification or optimisation.
3.2.3 Legislative framework
In the European Union,radiation protectionlegislation relating to ionising radiation derives from theEuratom Treaty. Its common objective is to establish uniformsafety standards to protect the health of workers, patients andof the general public and to ensure that they are applied. Thespecific requirements for radiation protection are laid down inTitle II Chapter 3 "Health and Safety", Articles 30 to 39 of theEuratom Treaty. This system has been embodied in variousEuropean Directives most notably the Basic Safety Standards(BSS, originally adopted in 1959 and last revised by CouncilDirective 96/29/EURATOM) and the Medical Exposure Directive(MED, 97/43/EURATOM).
The BSS lays down the requirements for the protection of thehealth of workers and the general public against the dangers ofionising radiation. Itencapsulates the principles of justification, optimisation anddose limitation and applies them to the regulatory system thatcontrols practices involving ionising radiation. The scope ofthe Directive is wide and incorporates requirements forreporting to the Competent Authorities of a wide range ofpractices involving the use of ionising radiation and for priorauthorisation of many of these practices. The BSS sets doselimits for workers and members of the public and requires thatworkplaces are organised in a way that delineates and controlsareas according to risk of exposure. The dose limitationrequirement does not apply to three distinct groups ofindividuals exposed as a result of the use of ionising radiationin medicine – patients, persons knowingly and willingly helpingpatients (but not as part of their occupation) and volunteers in(bio)medical research. The BSS specifies the dose limit forworkers as 100 mSv in a consecutive five-year period, subject toa maximum effective dose of 50 mSv in any single year. Formembers of the public, the limit is 1 mSv per year.
The Medical Exposure Directive (MED) deals with the healthprotection of individuals against the dangers of ionisingradiation inrelation to medical exposure. This Directive replaced thePatient Directive (84/466/EURATOM) and is the main legalinstrument dealing with the protection of patients undergoingdiagnostic and therapeutic procedures which utilise ionisingradiation.
The MED aims at eliminating the practice of unnecessarymedical exposures and to this end the principle of justificationis central to the Directive. Justification and optimisation areseen as key in implementingradiation protection inmedicine. The scope of the Directive includes not only patientsbut also other individuals exposed either directly orindirectly. This includes those exposed in occupational healthsurveillance, health screening, research and medico-legalprocedures. Passenger security scanning using ionising radiationis not addressed explicitly in the current text of either theBSS or the MED. However, it has been considered in the contextof the revision of the BSS which is currently underdiscussion.
Since the first BSS Directive was adopted, in 1958, it hasbeen updated many times. The latest update was in 1996. Afurther revised and updated version was submitted as aCommission proposal to the European Parliament and the Economicand Social Affairs Committee in September 2011. In addition tothe BSS, the proposal incorporates a revised version of the MEDalong with a number of other Directives which deal withradiation safety.The proposal and the opinions of the bodies mentioned above willbe further considered by the European Council prior to adoptionof a revised Directive. The following section describes thecurrent requirements and the proposed revisions of therequirements are described in section 188.8.131.52.
184.108.40.206 Medico-legal procedures
The MED defines medico-legal procedures as ‘proceduresperformed for insurance or legal purposes without a medicalindication’. In including medico-legal exposures within thescope of the MED Directive, the objective was to ensure thatpersons presenting for medico-legal procedures were afforded atleast the same level of protection as patients.
Medico-legal procedures were originally envisaged to be X-raysfor insurance purposes and X-rays arising as a result of legalproceedings. In fact, the definition of medico-legal proceduresis such that the scope is almost certainly wider. As aconsequence, the range of exposures that might be considered tobe medico-legal is both broad and diverse, extending beyondthose performed for insurance or as a result of legalproceedings. Exposures arising from the use of security scannersfor screening purposes fall under the broad category ofmedico-legal exposures.
Until such time as existing legislation is revised, theprovisions within the Medical Exposure Directive apply. Article5.4 of this Directive requires Member States to ensure thatprocedures are put in place that should be observed in the caseof medico-legal exposures. The Directive also requires thatspecial attention be given to the justification and optimisationof such exposures (Art 3.1 (d)).
Although medico-legal exposures are considered to be a sub-setof medical exposures, unlike medical exposures that are regardedas exposure of individuals as part of their own medicaldiagnosis or treatment, medico-legal exposures are not exemptfrom the public dose limit (96/29/EURATOM, Article 6.4).Therefore the dose limits set out in the BSS, for a member ofthe public, apply and so the limit for effective dose as aresult of medico-legal exposures, such as security scanning, isthat applicable to a member of the public. The categorisation ofexposures to staff that are required to be screened (airlinecrews, airport workers, couriers, and others) as part of theiroccupation is less clear. The current thinking within the ICRPseems to indicate that these will be considered as publicexposures rather than occupational and if this is the case thenthe public dose limit will apply.
220.127.116.11 Legal requirement for justification
The justification of practices involving ionisingradiation prior totheir introduction into routine use is a legal requirementenshrined in the BSS and the MED. The BSS requires Member Statesto ensure that all new types of practices are justified by theireconomic, social or other benefits in relation to the healthdetriment they may cause, in advance of being firstapproved.
In relation to justification, the BSS requires an explicitdemonstration of a positive net benefit before a practice can beauthorized by the regulatory body. As discussed in section3.2.2., justification is likely to be a complex task and MemberStates will require some mechanism to ensure that an appropriatelevel of consultation takes place, commensurate with theradiological and social significance of the type of practice,before it can be considered to be either justified orunjustified.
The justification process may result in particularrequirements being applied to these practices. Screeningtechniques, where the primary focus is security, could also beused to detect other contraband, such as illegal drugs, on aperson. However, in the case for justification, the applicantshould identify the primary purpose for introducing thetechnique to the Justifying Body and address issues that mayarise that are not pertinent to the primary purpose.
The fact that the doses arising from the use of screening forsecurity purposes may be well below the public dose limit doesnot remove the requirement for justification. In addition, forpractices that are justified and subsequently authorised,optimisation measures must be taken so that all exposures are aslow as reasonably achievable (the ALARA principle) for workers,the general public, and the population as a whole.
18.104.22.168 Revision of legislation
The European Commission has undertaken the simplification ofCommunity legislation in the area ofradiation protectionand has proposed the consolidation into a single text of fiveDirectives. The main Directive is the BSS. The remaining fourDirectives cover different specific aspects of radiation safetycomplementary to the overall BSS. This includes healthprotection during medical exposures (97/43/EURATOM), the controlof high activity sealed sources (2003/122/EURATOM),communication issues in an emergency situation (89/618/EURATOM)and the protection of outside workers (90/641/EURATOM).
One of the most significant changes in the revised Directiveis in the way exposures previously classified as medico-legalare dealt with. Those exposures have been redefined as‘non-medical imaging exposure’ and have been put underappropriate regulatory control. The new definition includes ‘anydeliberate exposure of humans for imaging purposes where theprimary motivation for the exposure is not related to the healthor well-being of the individual being exposed’. The need forjustification of such practices, in three stages as for medicalexposures, and for establishing associated conditions, has beenworked out, including the differentiation between proceduresimplemented by medical staff using medical equipment andprocedures implemented by non-medical staff using non-medicalequipment, as in security screening.
The BSS annual dose limit and corresponding constraints forpublic exposure apply, while allowing for some exceptions forsome specific non-medical exposure procedures carried out in amedical environment such as drug searches within thebody.
22.214.171.124 Implications of the Revised Directive forsecurity screening of passengers
The revised Directive requires a system of authorisation fornon-medical imaging exposures, including security screening. Therequirements for justification and optimisation have beenstrengthened. The Directive requires that, in addition to theinitial justification of the practice, each particularapplication of a generally accepted type of practice bejustified in advance. Each justification must also beperiodically reviewed by the Competent Authority. The CompetentAuthority must ensure that requirements for the practice,including criteria for individual implementation, areestablished as appropriate in cooperation with other relevantagencies and professional bodies.
The Competent Authority is required to ensure that doseconstraints are established for security screening and thatthese are set to ensure that annual doses to members of thepublic remain well below 1 mSv (see draft revised BSS, article23.3c). This dose criterion is likely to be readily achievable,even for the most frequently exposed groups (air crews, couriersand frequent flyers). The Directive requires that informedconsent of the individual to be exposed is sought, although itdoes allow for exceptions where law enforcement bodies mayproceed without consent, if that is permitted by nationallegislation. Finally, the revised Directive requires that wherethe exposure is routinely carried out for security purposes thescreened individuals are provided with a choice of analternative technique which does not involve exposure toionising radiation.