IONISING RADIATION REGULATIONS 99

Transcription

1 IONISING RADIATION REGULATIONS 99 & IRMER IONISING RADIATION MEDICAL EXPOSURE REGULATIONS BARBARA LAMB Specialist Radiographer Dental and maxillofacial radiography IRR99 The Ionising Radiations Regulations IRR99 relate principally to the protection of workers and the public relates to occupational exposure addresses the equipment aspects of patient protection Came into force in 1 st Jan 2000 Replace Ionising RadiationsRegulations1985 IRR 85 DOSE LIMITS (IRR99) Annual Dose Limits ( millisieverts msv) 20 msv Classified Workers 6 msv Non Classified workers(dentists) 1 msv Members of the public

2 DOSE CONSTRAINTS Annual Dose Constraints ( millisieverts msv ) 1 msv For employees directly involved with the radiography 0.3 msv For employees not directly involved with the radiography and members of the public Essential Legal requirements IRR99 Authorisation granted by Health and Safety Executive Notification Notification to Health and Safety Executive of routine use of dental x ray equipment and of any material changes to a notification including change of ownership of practice or move to new premises Prior Risk Assessment Must be undertaken before commencement of work Subject to regular review All employees recommended to record findings of risk assessment.this is a requirement with 5 or more employees 5 step approach recommended Identify the hazard ( routine or accidental exposure to x rays) Who might be harmed and how they may be affected Evaluate the risks and whether existing precautions adequate or more needed to be taken. If needed implement additional precautions Record findings of risk assessment Review risk assessment and revise if necessary Restriction of exposure(alarp) Overriding requirement to restrict radiation doses to staff and other persons

3 As Low As Reasonably Practicable Maintenance And Examination Of Engineering Controls Applies particularly to safety and warning features Contingency plans These should arise out of the risk assessment and be provided within the local rules RPA A suitably trained RPA must be appointed in writing and consulted to give advice on IRR99 The RPA should be an expert in radiation protection and will be able to advise on compliance with the Regulations and all aspects of radiation protection including Controlled and designated areas on all equipment Installation of new of modified equipment Periodic examination and testing of engineering controls safety features and warning signals Systems of work Risk assessment Contingency plans Staff training Assessment and recording of doses received QA programmes Information Instruction And Training Must be provided, as appropriate for all persons associated with dental radiography Designated Areas During exposure a controlled area will normally be designated around the x ray set to aid effective control of exposures Area will be defined as within the primary x ray beam until attenuated by distance or shielding and within 1.5 metres of the x ray tube and patient Radiation Protection Advisor New Legal Instigationfrom-1 st Jan 2000

4 Reg 13 of IRR99 no exemptions RPA is mandatory Usually a dentist or senior member of staff should be appointed to ensure compliance withirr99 and Local Rules RPS should be adequately trained and closely involved with the radiography and also have authority to adequately implement their responsibilities LOCAL RULES All practices should have written set local rules in relation to radiation protection measures within that practice applying to all employees including: Name of RPS Identification and description of controlled area Summary of working instructions including names of staff qualified to use the equipment, details of their training and instructions on use of equipment Contingency arrangements for equipment malfunction and/or accidental exposure to radiation Named person with Legal Responsibility Details and results of dose Investigation Levels (Dose constraint of no more than 1mSv for practice staff in a dental practice) Name and contact details of RPA Arrangements for personal dosimitry Arrangements for pregnant staff Reminder of legal responsibilities under IRR99 Name and contact details of RPA Arrangements for personal dosimitry Arrangements for pregnant staff Reminder of legal responsibilities under IRR99 DUTY OF MANUFACTURERS Critical examination and report of all new or significantly modified x-ray equipment CRITICAL EXAMINATION SHOULD INCLUDE Including:

5 A clear and unambiguous description of equipment and its location An evaluation of the acceptability of the location in relation to the operator s position and the rooms warning signs and signals An evaluation of the acceptability of equipment s warning signals The evaluation of the acceptability of the exposure control Confirmation that the equipment safety features are in place and operating correctly e.g. Beam dimensions and alignment, beam filtration and timer operation And overall conclusion as to whether or not the equipment safety features are operating correctly, the installation is providing sufficient protection of persons from exposure to x-rays and whether the user has been provided with adequate information about proper use, testing and maintenance of equipment ACCEPTANCE TEST THIS IS THE USERS RESPONSIBILITY All the equipment must be critically examined and acceptance tested before being put into clinical use and then routinely tested as part of quality assurance program. The acceptance test in addition to the features covered in the critical examination should include Measurements to determine whether the equipment is operating within agreed performance parameters e.g. Kv ma and timer accuracy An assessment of the for typical patient dose for comparison with National diagnostic reference levels A view and record of film, film / screen combinations and processing details and an evaluation of the adequacy of processing. A permanent record should be made of the results and conclusions of all the tests and they should be retained as part of the QA program and all deficiencies should be rectified ALL EQUIPMENT, X-RAY GENERATING AND IMAGE RECEPTORS, SHOULD COMPLY WITH THE GENERAL REQUIREMENTS NAMELY: INTRA ORAL RADIOGRAPHY Tube voltage should not be lower than 50 kv new equipment should operate within the range Kv All equipment should operate within 10% of the stated or selected Kv setting beam diameter should not exceed 60 mm at the patient end of the spacer cone

6 Rectangular collimation should be provided in new equipment and fitted to existing equipment at the earliest opportunity and the beam size should not exceed 40 x 50 mm Total beam filtration should be 1.5 mm of aluminium for sets operating below 70 kv and 2.5 mm of aluminium for sets operating above 70 kv and should be marked on the tube housing The focal spot position should be marked on the outer casing of the tubehead Focal spot to skin distance( FSD) should be at least 100 mm for sets operating below 60 Kv and 200 mm for sets operating above Film speed controls and finally an adjustable exposure time settings should be provided The fastest film available i.e. E F speed that will produce satisfactory diagnostic images should be used PANORAMIC RADIOGRAPHY Equipment should have a range of tube potential settings preferably from 60 to 90 Kv The beam height at the receiving slit of the cassette holder should not be greater than the film in use normally 125 mm or 150 mm in width of the beam should not be greater than 5 mm Equipment should be provided with adequate patient positioning aids incorporating light beam markers New equipment should provide facilities for field limitation techniques. CEPHALOMETRIC RADIOGRAPHY Equipment must be able to ensure the precise alignment of the x-ray beam, cassette and patient The beam should be collimated to include only the diagnostically relevant area To facilitate the imaging of soft tissue an aluminium wedge filter should be provided at the x-ray tube head in preference to one at the cassette All equipment Should have a light on the control panel to show that the mains supply is switched on Should be fitted with a light that gives a clear and visible indication to the operator that an exposure is taking place and audible warnings should also provide the operator with the same information

7 Exposure switches ie timers should only function while continuous pressure is maintained on the switch and terminate if pressure is released Exposure switches should be positioned so that the operator can remain outside the controlled area and at least 2 metres from the x-ray tube and patient Exposure times should be terminated automatically DUTIES OF THE EMPLOYEES e.g. DENTAL CARE PROFESSIONALS Notwithstanding the many and varied responsibilities based on a person legally responsible ie the legal person, IRR99 places overriding responsibilities on the employees such as dental care professionals which includes Not knowingly expose themselves or any other person to x-rays to an extent greater than is reasonably necessary for the purposes of the work To exercise reasonable care when working on any aspect of dental radiography To immediately report to the legal person whenever they have reasonable cause to believe that an incident or accident has occurred with the x-ray equipment and that the or some other person have received an overexposure ROUTINE TESTING Similar content to an Acceptance test Emphasis on Confirmation that no significant changes have been made in relation to equipment,its location and its acceptability of location Attention paid not just to the technical tests but comparison of them in relation to previous tests Identify and rectify trends suggesting possible deterioration

8 IRMER Ionising Radiation (Medical Exposure) Regulations These regulations are concerned with the safety of patients They came into force on 13 MAY 2000 They replace the Ionising Radiation (Protection of Persons Undergoing Medical Examination or Treatment )Regulations 1988 that is IRR 88 Essential Legal requirements IRMER 2000 Duties of Employers-written procedures Written procedures to identify Patients Identification of referrers/practitioners/operators Authorisation and justification of exposures Justification of Medico Legal exposures Identification of pregnant patients Compliance with QA programmes Assessment of patient dose Use of diagnostic levels Carrying out and recording clinical evaluation Reducing probability and magnitude of accidental and unintended doses to patients Provision for clinical audit Written Protocols and guideline exposure settings for every type of standard projection for each item of equipment Procedures for overexposure (not machine malfunction) It is recommended that these employers written procedures and the local rules are kept together as the RADIATION PROTECTION FILE

9 DUTIES OF THE REFERRER PRACTITIONER OPERATOR THE REFERRER A registered doctor or dentist or other health professional entitled to refer a patient to a practitioner for a medical exposure. The referrer is responsible for supplying the practitioner with sufficient information to justify an appropriate exposure Must have been a history and clinical examination previous to the referral Previous radiographs should accompany the patient if relevant Diagnostic information entered in writing THE PRACTITIONER A registered doctor or dentist or other health professional entitled to take responsibility for a medical exposure ( specialist radiographer ). The practitioner must be adequately trained to take decisions and the responsibility for the justification of every exposure THE OPERATOR The person conducting any practical aspect of a medical exposure Practical aspects include: patient identification positioning film, patient or x-ray tubehead Setting of exposure options Pressing the exposure switch to initiate the exposure Processing films Clinical evaluation of exposures Exposing test objects as part of QA programme The operator must be adequately trained for their role in the exposure

10 JUSTIFICATION OF INDIVIDUAL MEDICAL EXPOSURE Before and exposure can take place it must be justified (i.e. assessed to ensure that it will lead to a change in the patient s management and prognosis) by an IRMER practitioner and authorised as the means of demonstrating that it has been justified Every exposure should be justified on the grounds of The availability and/or findings of previous radiographs The specific objectives of the exposure in relation to the history and examination of the patient The total potential diagnostic benefit to the patient The radiation risk associated with radiographic examination The efficacy, benefits and risks of alternative techniques having the same objectives involving no or less exposure to ionising radiation HISTORY AND CLINICAL EXAMINATION ARE THE ONLYACCEPTABLE MEANS OF DETERMINING THAT THE MOST APPROPRIATE OR NECESSARY RADIOGRAPHIC VIEWS ARE REQUESTED OPTIMISATION All doses must be kept as low as reasonably practicable ALARP Apply QA procedures to the optimisation of patient dose CLINICAL AUDIT Provision must be made for clinical audit EXPERT ADVICE Involvement of Medical Physics expert for advice on measurement and optimisation of patient dose usually the RPA can act as the MPE EQUIPMENT Keeping and maintenance of itemised inventory of equipment including: Name of manufacturer Model no Serial no Year of manufacture Year of installation

11 ADEQUATE TRAINING AND CONTINUING EDUCATION OPERATORS AND PRACTITIONERS must have received adequate training and must undertake continuing education and training after qualification Nature of training is in the GUIDANCE NOTES((see below) Recommended publications: Selection Criteria for Dental Radiography Published By: Faculty of General Dental Practitioners (UK) Royal College of Surgeons of England Guidance Notes for Dental Practitioners on the Safe Use of X-Ray Equipment Published by: National Radiological Protection Board Orthodontic Radiographs Guidelines Published by: British Orthodontics Society Guidelines on Radiology Standards for Primary Dental Care