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Dental Radiology. A brief(!) overview. JUSTIFICATION, OPTIMISATION, LIMITATION!. Balance risk against benefit, primary risk of dental radiography is cancer induction Risk is age & tissue dependent X-rays are short wavelength, high frequency EM radiation=high energy=ionisation of atoms
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Dental Radiology A brief(!) overview
JUSTIFICATION, OPTIMISATION, LIMITATION! • Balance risk against benefit, primary risk of dental radiography is cancer induction • Risk is age & tissue dependent • X-rays are short wavelength, high frequency EM radiation=high energy=ionisation of atoms • DNA mutations can be stochastic (chance) or deterministic (due to increased dose-not relevant to dental radiography) • Absorbed (Gy) actual value of radiation • Equivalent (Sv) accounts for type of radiation (x-rays in dentistry) • Effective (Sv) accounts for tissue type which has been irradiated (more damaging to certain tissues) • F-speed film/digital sensor(preferred standard) • Use of holders and paralleling technique • 60-70kV, DC instead of AC is preferred • Rectangular collimator, open ended spacer cone & long FSD (200mm) • Range of available exposure times to account for variations in anatomy of different areas and size of patient to produce adequate image for minimum exposure
Intra-oral films are superior for diagnosing common dental pathoses to panoramic radiography • Routine radiography in absence of clinical signs/symptoms cannot be justified • Panoramic use can be argued in grossly neglected mouth or where severe generalised periodontal disease, instead of full mouth PAs, orthodontic treatment, surgical removal of 3rd molars, mandibular fractures/major trauma • Children: If canines not palpable by age 11 in buccal sulcus- PA radiograph • BWs: in all children of high caries risk, then 6 monthly until no new caries detected, annually for moderate caries risk • Low caries risk, 12-18 monthly in primary dentition, 2 yearly in permanent, can extend interval if continued evidence of low risk **Also, see EAPD approach for child intervals • Recommended bitewing intervals for adults are the same as for children • Pregnancy: no need to delay dental radiography but can be emotional issues so discuss delaying with patient if non-urgent radiographs, record discussion & decision in notes
FGDP Selection Criteria for Dental Radiography 2018: New Adult Patient Assessment
Periodontal radiography • Only take radiographs when clinical examination has been carried out & justifies exposure • BPE 3, 4-5mm pocketing= BWs • BPE 4, >6mm pocketing= vertical BWs, & PAs where bone not visible on vertical BW • Supectedperio-endo lesion=PA • Additional PAs of selected anterior teeth only if likely to change management of patient as result • Evaluate existing radiographs for evidence prior to taking radiographs for periodontal assessment • OPT can also be used if optimal quality, or may require combination of this & PAs, or PAs only
Endodontics/Trauma • Pre-operative diagnostic radiograph & post-operative radiographs essential (PA) • PA after 1 year for follow-up is advised, also taking into account clinical signs/symptoms to assess resolution • Suggested 4 year follow-up by European Society of Endodontology, FGDP guidelines state not essential • Trauma: baseline PA radiograph to be taken, then at 6 months, and annually until root formation complete, no evidence to support exact intervals for retaking radiographs in trauma monitoring
Grading radiographs • 1=No errors in patient preparation, exposure, positioning, processing or film handling (minimum 70% should be grade 1) • 2=Some errors in patient preparation, exposure, positioning, processing or film handling but which do not detract from diagnostic utility of the radiograph (maximum 20% grade 2) • 3=Errors in patient preparation, exposure, positioning, processing or film handling which render the radiograph diagnostically unacceptable (maximum 10% grade 3) • If grade 3 radiograph, reason for grade 3 should be recorded and exposure should be retaken • Representative samples of radiographs should be audited at minimum 12 monthly intervals to ensure quality of radiographs is being maintained
IRMER 2017 • Protects those undergoing exposure to radiation • Local rules should contain all relevant information • Justification-all exposures must be of diagnostic benefit • Optimisation-dose as low as reasonably practicable, maximum information for minimum exposure, DRLs to be recorded in Local Rules • Limitation-equipment, previous radiographs? • Duty holders: Employer, Referrer, Practitioner, Operator (definitions of each) • Clinical audit regularly for QA • Employer must ensure regular maintenance & testing of equipment & evidence of duty-holder training • Written procedures for exposure of a radiograph must be included in Local Rules • RECORD: Justification for exposure, type of radiograph, intended information to be gathered, parameters-only if outwith normal set in Local Rules, then after exposure made, grading of quality of radiograph, report on findings from this
IRMER 2017 Changes • Replaces IRMER 2000 • MPE must be appointed by the practice (approved list available of UK MPE’s) • 3 additional written procedures: • 1. Benefits & risks-procedure where patient(or carer) must receive explanation of benefits & risks prior to exposure • 2. Comforters & Carers- guidance required for those involved in supporting patient during exposure and dose constraints specified for them • 3. Incidents & Accidents-Must have procedure for investigating unintended exposures & referrer, practitioner and person undergoing exposure must be notified of any clinically significant incident & the outcome of the investigation • Non-medical exposures: note if these are carried out and record parameters for justification of this type of exposure if taken in practice • QA programme moved from IRR to IRMER, testing every 3 years for OPT & intra-oral units, annual for hand-held and CBCT, keep records for 2 years • Critical examination-testing of equipment prior to first use
Ionising Radiation Regulations 2017 • Applies to persons working with radiation and those in the environment, not to patients undergoing exposure • Must carry out risk assessment, and ensure radiation exposure of workers and the public is ‘as low as reasonably practicable’ • Local rules to be produced & displayed • Controlled Area to be designated, 1.5m minimum distance from source & out of primary beam • RPA= Radiation Protection Advisor, usually Medical Physicist, advises on doses etc • RPS=Radiation Protection Supervisor, within practice, person in charge of managing local radiation safety, producing local rules & ensuring all staff adhere • Classified workers effective dose limit 20 mSv a year (trainees under 18 <6mSv) • All others effective dose limit 1mSv per year • In pregnant workers, equivalent dose to the foetus is as low as is reasonably practicable & <1 mSv • ensure that an investigation is carried out without delay when the effective dose of ionising radiation received by any of its employees for the first time in any calendar year exceeds 15 mSv
IRR 17 Changes • Replaces IRR 99 • Mandatory registration with HSE prior to commencing using radiation, one off fee £25 (under intermediate risk category, classified as ‘working with radiation generators’) • Estimated annual dose of radiation received by members of the public is to be noted, RPA can advise on this, record in risk assessment, and also annual estimated dose to classified workers • Contingency plan incase of accidents/incidents involving x-rays & investigation must be carried out if these occur. • Records to be kept for 2 years
Resources • http://www.legislation.gov.uk/uksi/2017/1075/pdfs/uksi_20171075_en.pd • http://www.legislation.gov.uk/uksi/2017/1322/contents/made • https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/337178/misc_pub_DentalGuidanceNotes.pdf • file:///C:/Users/Chris%20&%20Jen/AppData/Local/Packages/Microsoft.MicrosoftEdge_8wekyb3d8bbwe/TempState/Downloads/s13%20(1).pdf • https://www.proprofs.com/quiz-school/story.php?title=oral-radiology-practice-examination • www.columbia.edu/itc/hs/dental/sophs/material/quizzes/quiz1.html