This website uses non-intrusive cookies to improve your user experience. You can visit our cookie privacy page for more information.

Radiation Protection Adviser

Issue 2 July 1992


The first issue of The Radiation Protection adviser was successful to the extent that we ran out of copied. We apologise to those of you who did not receive a copy.

It prompted correspondence on critical examination of newly installed dental radiography equipment. This issue therefore contains a further article that looks at critical examinations of installed equipment in general and considers the duties of all the parties involved in the chain of supply. Another article is of the "lessons learnt" type and covers a site radiography incident. The recently published HSE leaflet on radon in the workplace is also mentioned. Further articles cover Regulation 33 guidance, recognition of the qualified expert and the Ionising Radiations Special Entries Committee.

References to IRR 85 or ACOP Parts 1, 2, 3 and 4 are references to the Ionising Radiations Regulations 1985 and the four parts of the Approved Code of Practice supporting the regulations.

Again I would welcome your .views on the newsletter, the material in it, and suggestions for future articles. I would like to thank those of you who have already written to me - your comments have been of interest and value.

Queries and comments should be addressed to the Editor:
Ann Loach,
The Editor,
RPA Newsletter,
Health and Safety Executive
Level 6,
North Wing,
Rose Court,
2 Southwark Bridge,
London SE1 9HS


A few months ago an incident happened during site radiography which could have resulted in the over-exposure of a site radiographer. It happened after non-destructive testing work using mobile radiography equipment.

The employee who had been using the equipment removed the drive cable and started to release the guide tube from the source container when he noticed that the source carrier was still inside the guide tube. He used his emergency training to return the source to the shielded container immediately. Fortunately he only received 11 mSv skin dose and 9 mSv whole body dose. However this dose could have been much higher if the worker had not spotted the detached source when he did.

When the empty source container was examined after the incident it was clear that the drive mechanism had not been properly maintained. Even so, it is unlikely that the employee would have received a significant exposure to ionising radiation as a result of the incident if a safe system of work had been provided and set out in local rules (IRR 85 Regulation 11(1)).

The employer should have set out a proper procedure for site radiography which included obligatory checks for radiation levels after each exposure, using adequately maintained and tested monitoring instruments (IRR 85 Regulation 24). These checks would verify that the source had returned properly to its container (ACOP part 2. paragraph 67).

Any employee required to use monitoring instruments should be trained to use them properly; a battery function check should always be made before the instrument is used. The employer should also have appointed a radiation protection supervisor (IRR 85 Regulation 11(3)) to supervise the work with ionising radiation.

Source disconnection during site radiography is a well recognised problem and has led on a number of occasions to the inadvertent exposure of workers to ionising radiation. RPAs have an important role with respect to site radiography in providing adequate advice about good practice and efficient communications.

[Back to top]


In June HSE published guidance note The fitness of equipment used for medical exposure to ionising radiation, ISBN 011 88631 4, giving advice about the requirements of Regulation 33 IRR 85. The guidance is aimed at employers and others in the health services who may be concerned with the fitness of equipment used in connection with medical exposures to ionising radiation, for the purposes of diagnosis, therapy or as part of scientific research.

The new publication explains the need to ensure. so far as is reasonably practicable, that such equipment is selected, installed and maintained in order that the intended diagnosis, therapy or research can be carried out with the minimum of exposure. It also gives advice about the importance of calibrating radiotherapy equipment and reproduces the recently revised recommendations on this subject by the Institute of Physical Sciences in Medicine.

Guidelines are also given in the publication about the need to notify HSE when it is suspected that an incident has happened in which a fault with radiation equipment has led to a patient or research volunteer receiving an exposure to ionising radiation that is much greater than intended.

Copies of the guidance can be ordered from The Staionery Office (Tel: 0171 873 9090)

[Back to top]


We received a number of letters about the article in the first issue of the newsletter on the appointment of suitably trained and experienced dental equipment engineers as RPAs for the limited purpose of conducting critical examinations on simple installed dental X-ray equipment.

It is important to recognise that the qualifications and experience of an RPA required by IRR 85 should correspond to the scope of advice required by the employer. The functions of a person appointed as an RPA solely for the purpose of undertaking routine critical examinations of installed dental equipment will usually be limited. So it would be unreasonable to expect the appointment to cover many of the matters listed in paragraphs 71 and 75 of ACOP Part 1. However, for most installations the critical examination will usually be sufficiently complex to require the involvement of an appointed RPA who is a specialist in radiation protection matters.

Critical examinations are required by Regulation 32 of IRR 85 and are the responsibility of the erectors or installers. A critical examination should ensure that the installation satisfies the original design criteria or performance standards relevant to the restriction of exposure. Any safety features and warning devices provided must operate correctly and sufficient protection must be provided for those likely to be exposed to ionising radiation when the article is in use.

However, it should not be necessary to consider the intrinsic safety of the equipment as designed and manufactured since this aspect should be dealt with by the supplier under section 6 of the Health & and Safety at Work etc Act 1974 (as modified by Regulation 32(1) IRR 85).

The critical examination must be undertaken with the involvement of an RPA whose scope of appointment includes a advice on the category of equipment. The RPA may either be the installer's own RPA (appointed under Regulation 10 of IRR 85) or the user's RPA. The installer and the user should agree before installation commences whose RPA will be involved with the critical examination.

The responsibility for carrying out the critical examination rests with the erector or installer, not with the RPA or the user. However, the examination should be carried out to a protocol agreed in advance with the RPA who should also accept the results of the examination. The RPA should be satisfied as to the competency of anyone who undertakes, checks or carries out measurements as part of the critical examination. Furthermore, the RPA should be present for at least part of the critical examination; in most cases this will probably be at the final check of the installation.

In addition, everyone involved in the chain of supply must ensure that clear,' unambiguous and comprehensive information is passed along the chain to the user of the article (paragraph 178 of ACOP part 1).

[Back to top]


HSE has published discussion document Radiation protection: recognition of the qualified expert on whether the UK should change its approach to the appointment of RPAS. It describes the current practice and legal position in respect of the recognition of qualified experts in radiation protection in the UK and other EC Member States, takes account of related activities (the Diploma Directives) and offers three possible options for the future. It does not recommend any particular line of action but seeks comment and proposals from interested parties (closing date 31 July 1992).

[Back to top]


Any employer who suspects that the dose received by an employee is much greater than or much less than that shown in the dose record must investigate the circumstances of the exposure in liaison with the RPA. If the investigation confirms any suspicion, the employer must apply to HSE for a special entry to the dose record under Regulation 13(8) IRR 85. HSE is advised on these applications by its Ionising Radiations Special Entries Committee (IRSEC).

In the past there have been some delays or difficulties in the processing of applications because either the employer's investigation was insufficient or HSE was not supplied with adequate information on Which to base a decision. For example, a copy of the individual's dose record for the period in question (and adjacent periods where relevant) should normally be supplied. This is quite often overlooked and requires HSE to make further enquiries which causes delay.

The employer, in consultation with the RPA, should always provide an estimate of the likely dose received during the period in question to replace the recorded dose. Quite often this requires a reconstruction of events, which is helpful in considering the adequacy of a case made for special entry. Evidence from co-workers may also be relevant.

Problems have also occurred where the actual wear period differed from the recorded issue period, because more than one dosemeter had been issued for a particular recording period.

Under normal circumstances, IRSEC is unwilling to consider applications where the proposed change to the recorded dose for one individual is less than 1 mSv if the dose recorded is up to 1 mSv or less than a factor of 2 for recorded doses between 1 mSv and 50 mSv. However IRSEC may also consider applications which concern more than one recording period or which affect a group of workers. IRR 85 does not permit an ADS to alter records unless approved to do so by HSE.

RPAs should remind employers that the first point of contact for applications for special entries is the site inspector or the appropriate HSE area office. Other enquiries of a technical nature should be directed to the Secretariat (IRSEC), Room 405, Technology and Health Sciences Division, Magdalen House, Bootle L20 3LZ.

[Back to top]


Radon is a naturally occurring gas which decays to form tiny radioactive particles which may be breathed into the lungs. Radiation from these particles can cause lung cancer. In certain regions of the country some workplaces are likely to have high indoor radon levels. Because of the risk to the health of employees from exposure to radon, IRR 85 require employers to take action where radon is present above a defined level.

HSE has produced a simple leaflet called Radon in the workplace IND(G)123(L) which draws attention to the risks of radon at the workplace. It is aimed at employers, employees and their representatives. The leaflet has three distinct parts covering:

  1. Background facts about radon;
  2. radon in the workplace; and
  3. sources of information and advice.

[Back to top]

Updated 2017-10-11