TEST GDP DCP. Dental Hygienists and Therapists. Radiography and Radiation Protection. Radiography and Radiation Protection IR(ME)R 2000

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1 Radiography and Radiation Protection IR(ME)R 2000 J Makdissi DDS IQE MMedSc FDSRCS(Eng.) DDRRCR Clinical Senior Lecturer and Honorary Consultant Dental and Maxillofacial Radiology GDP a) Radiation physics b) Risk of ionising radiation c) Radiation doses d) Factors affecting doses e) Radiation protection f) Statutory requirements g) Quality Assurance h) Selection Criteria DCP a) Radiation physics b) Risk of ionising radiation c) Radiation doses d) Factors affecting doses e) Radiation protection f) Statutory requirements g) Quality Assurance h) Selection Criteria Dental Hygienists and Therapists prescribe radiographs take, process and interpret various film views used in general dental practice TEST 1

2 Properties of X-ray 1. Part of the electromagnetic spectrum 2. Travel in straight lines 3. Undetected by human senses 4. All of the above 5. None of the above 1. Tungsten 2. Aluminium 3. Lead Does Filtration use? kv Affects 1. Contrast 2. Degree of blackening 3. Resolution The coolant in X-Ray machine 1. Water 2. Oil 3. Ice 4. CO 2 5. Ethyl Chloride 1. Silver 2. Lead 3. Copper 4. Tin 5. Tungsten The filament is made of Which film needs the least exposure time? 1. C - Speed 2. D - Speed 3. E - Speed 4. F - Speed 5. All of them have same exposure time 2

3 Increase in ma will result in 1. Lighter image 2. Darker image 3. Less contrast Increase kv will result in 1. Better contrast 2. Lesser contrast The UK annual background radiation What % of radiographs should be of Grade 1 quality? Sv ksv msv µsv 1. 10% 2. 20% 3. 50% 4. 70% The recommended frequency of bitewing radiography in high caries risk adults is 1. 3 months 2. 6 months months months The recommended frequency of bitewing radiography in high caries risk children is 1. 3 months 2. 6 months months months 3

4 The recommended frequency of bitewing radiography in low caries risk adults is The recommended frequency of bitewing radiography in low caries risk children is 1. 6 months months months months 1. 6 months months months months In the case of accidental overexposure you should keep the records for 1. 7 years years years years This course is a requirement of 1. IRS IRR IREER IRMER 2000 Somatic deterministic effects 1. Malignancy 2. Cataract Somatic non deterministic effects 1. Malignancy 2. Cataract 4

5 Highest tissue weighting factor 1. Brain 2. Skin 3. Gonads 4. Bone marrow Lowest possible dose from an intra-oral radiograph is 1. 1 sv 2. 1 msv 3. 1 µsv One panoramic radiograph equals a full mouth periapical series approximately One panoramic radiograph equals approximately 1. Return flight to Spain 2. Return flight to the US 3. Return flight to the moon 1. Yes 2. No You should have dosimeters in your practice if your weekly workload is intra-oral or 50 Panoramic intra-oral or 100 Panoramic 3. Whatever your workload is 4. You do not have to have them Follow up radiograph in Endodontics is justified in 1. 1 year 2. 4 year 3. Both 4. No follow up 5

6 Gross caries can justify the taking of a panoramic radiograph? 1. True 2. False What am I interested in? Dose Image quality Manufacturer Variable kv Your X RAY machine X-RAY TUBE kv kv ma Time Variable ma Filtration...mm Cathode Anode Digital option ma AC or DC Collimation Rectangular/Round Date of last service kv mas 50kV 1mA 70kV 5mA 90kV 10mA 6

7 Rectification Aluminium filtration AC DC Rectangular Collimation Equipment log Details of all X-ray equipment in practice Critical examination Acceptance test Routine safety tests Day-to-day checks for safe working of equipment All maintenance records & faults Radiation MECHANISMS OF DAMAGE BY RADIATION Direct damage DNA/RNA Indirect Damage Water Molecules Disruption of nucleic acid bonds Mutation Radiolysis of H 2 0 Free Radicals H 2 and H 2 O 2 7

8 HARMFUL EFFECTS OF RADIATION Somatic deterministic effects Threshold dose Cataract formation Obliterative Endarteritis Somatic Non- deterministic effects NO threshold Malignancy RADIATION ABSORBED DOSE D O S E The amount of ENERGY absorbed from the radiation beam per unit mass of tissue 8

9 EQUIVALENT DOSE Radiation weighting factor EFFECTIVE DOSE Tissue weighting factor W T ICRP 1990 ICRP 2007 X-rays and Gamma rays 1 Neutrons 5-20 Alpha particles 20 Testes and Ovaries Red bone marrow Breast Salivary Glands Not included 0.01 Thyroid Panoramic Dose Including salivary glands in calculations µsv 1 INTRAORAL FILM 0.3 µsv 21.6 µsv used to be NOT including salivary glands in calculations 7 14 µsv 1 µsv 8.3 µsv Radiographic technique Effective dose (µsv) References WHAT CAN I COMPARE THIS RADIATION DOSE WITH? Intra-oral radiograph ,32,33 (bitewing/periapical) Panoramic Radiograph ,21,32-42 Lateral cephalometric radiograph ,36,42-46 Background radiation Flying distance CBCT (small field of view*) ,47-53 CBCT (medium field of view**) ,35,37,42,47-55 CBCT (large field of view***) ,21,35,41,51,52,54-56 CBCT (extended field of view****) ,21,41,42,46,47,54-58 CT scan (mandible) ,36,47,50 CT Scan (mandible and maxilla) ,54,59 9

10 Dose comparison ICRP 1990 ICRP 2007 Large FOV CBCT 37 µsv 806 µsv 68 µsv 1073 µsv Medium FOV CBCT 28 µsv 264 µsv 69 µsv 560 µsv Small FOV CBCT 66 µsv 203 µsv 189 µsv 652 µsv MDCT 285 µsv 453 µsv 534 µsv 860 µsv Justification Dose Reduction Techniques Optimisation Limitation Justification The benefit to the patient from the exposure should outweigh the detriment. Justification The availability and 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 individual The radiation risk associated with the radiographic examination The efficacy, benefits and risk of available alternative techniques having the same objective but involving no, or less, exposure to ionizing radiation. 10

11 Optimisation it is necessary to reduce patient doses to as low as reasonably practicable consistent with the intended purpose Limitation The equivalent dose to individuals shall not exceed the limits recommended by the ICRP Dose Reduction Techniques FSD Equipment Clinical decision Practical technique Diagnostic Interpretation Rectification Aluminium filtration AC DC 11

12 HIGH kv LOW mas Rectangular Collimation 12

13 Dose Is digital less than conventional? VANDENBERGHE et al 2011 The use of digital sensors compared to film allowed 15 90% dose savings Solid-sate sensors allowed radiation dose reductions of approximately 50% compared to PSP FARRIER et al 2009 Lower radiation dose was achieved with CCD Although more repeat was required BERKHOUT et al 2004 The dynamic range (LATITUDE) of phosphor plate systems is wide which could result in higher dose than necessary More retakes were needed when periapical radiography was performed using DR (28%) compared with film (6%) 13

14 Latitude: Conventional Latitude: Digital 5 mas 8 mas 15 mas 5 mas 8 mas 15 mas Dose Reduction Techniques Equipment Clinical decision Practical technique Diagnostic Interpretation REMIT Developing Dentition Caries Diagnosis Periodontal Assessment Endodontics Implant dentistry Good Practice 14

15 Dose Reduction Techniques Equipment Clinical decision Practical technique Diagnostic Interpretation LEAD APRONS There is no justification for the routine use of lead aprons in dental radiography The use of lead aprons during panoramic radiography is positively discouraged Guidelines on Radiology Standards in Primary Dental Care NRPB / RCR Working Party 1994 Female patients of child-bearing age Justification Optimisation Possible delay Lead for psychological reasons Radiation Protection File Local Rules - as required under IRR99 Written procedures - as required under IR(ME)R 2000 The Controlled Area The controlled area in the dental surgery will only exist when x-rays are being taken. In deciding the extent of the controlled area it is usually satisfactory if the controlled area is chosen to be: Within the primary x-ray beam until it has been sufficiently attenuated by distance or Shielding and within 1.5m of the x-ray tube and the patient in any other direction. 15

16 The radiation protection advisor is able to provide advice on the design of the x-ray room or the controlled area. Either the room has to be large enough to allow the operator to stand well outside the controlled area, in other words, preferably 2m or maybe more from the x-ray tube and the patient, and for sure well out of the direction of the primary beam. If distance is not sufficient to provide staff protection it is important to utilise shielding. The correct amount of shielding that is needed to secure the safety of staff within any controlled area is determined by the x- ray beam Ionising Radiations Regulations 1999 IRR st January 2000 Replaced the Ionising Radiation Regulations 1985 Safety of workers and the public Ionising Radiation (Medical Exposure) Regulations 2000 IR(ME)R th May 2000 Replaced the Ionising Radiation (Protection of Persons Undergoing Medical Examination or Treatment) Regulations 1988 Safety of patients Referrer Practitioner IR(ME)R 2000 Operator Employer (Legal Person) 16

17 Installation X-ray machine H&S Executive notification Risk assessment Equipment & maintenance log Contingency plan Radiation Protection Advisor Radiation Protection Supervisor Adequate training for x-ray staff Designate controlled areas Establish a Quality Assurance Programme Unintended Exposure 20X: Which regulation applies? Which authority needs to be informed? Causes Regulations Notifying authority Due to equipment malfunction Due to Clinical error, error of judgement, operator error Ionising Radiation Regulation 1999 (IRR 99) Ionising Radiation (Medical Exposure) Regulations 2000 IR(ME)R 2000 Health and Safety Office IRMER Inspectorate Radiation Protection File Local Rules - as required under IRR99 Written procedures - as required under IR(ME)R 2000 Local Rules RPS RPA Controlled Areas Personal dosimetry arrangements Arrangements for pregnant staff Written procedures QUALITY ASSURANCE Identification of referrers, practitioners, operators QA programme Clinical evaluation of outcome of all exposures 17

18 Aims of QA Programme Procedures To produce diagnostic radiographs of consistently high standard To reduce the radiation dose to patients and staff Image quality Patient dose and x-ray equipment Darkroom, films and processing Working procedures Personnel & training Audits Resolution What is IMAGE QUALITY? Number of pixels Line pairs per mm IMAGE QUALITY Is digital better than conventional? Digital = Conventional Diagnosis of recurrent caries A comparison of the accuracy of digital and conventional radiography in the diagnosis of recurrent caries. Anbiaee N, Mohassel AR, Imanimoghaddam M, Moazzami SM. J Contemp Dent Pract Dec 1;11(6):E

19 CCD = Conventional Accuracy of direct digital radiography for detecting occlusal caries in primary teeth compared with conventional radiography and visual inspection: an in vitro study. Dias da Silva PR, Martins Marques M, Steagall W Jr, Medeiros Mendes F, Lascala CA. Dentomaxillofac Radiol Sep;39(6): PSP ~ Film Comparison of digital systems and conventional dental film for the detection of approximal enamel caries. Pontual AA, de Melo DP, de Almeida SM, Bóscolo FN, Haiter Neto F. Dentomaxillofac Radiol Oct;39(7): Conventional > Digital Image Subjective image quality of digitally filtered radiographs acquired by the Dürr Vistascan system compared with conventional radiographs. Yalcinkaya S, Künzel A, Willers R, Thoms M, Becker J. Oral Surg Oral Med Oral Pathol Oral Radiol Endod May;101(5): PSP > Conventional Intra-oral storage phosphor and conventional radiography in the assessment of alveolar bone structures. Kaeppler G, Vogel A, Axmann-Krcmar D. Dentomaxillofac Radiol Nov;29(6): Digital > Conventional Comparison of two imaging modalities: F- speed film and digital images for detection of osseous defects in patients with interdental vertical bone defects. Jorgenson T, Masood F, Beckerley JM, Burgin C, Parker DE. Dentomaxillofac Radiol Dec;36(8): Film = CCD = PSP = CBCT Diagnostic accuracy of different imaging modalities in detection of proximal caries. Senel B, Kamburoglu K, Uçok O, Yüksel SP, Ozen T, Avsever H. Dentomaxillofac Radiol Dec;39(8):

20 Subjective Assessment Rating Quality 1 Excellent 2 Diagnostically acceptable 3 Unacceptable Targets Rating Percentage 1 Not less than 70% 2 Not greater than 20% 3 Not greater than 10% Preparation, positioning, exposure or processing Audit Rating Recommended Rushton, Horner et al Not < 70% 0.8% 2 Not > 20% 66.2% 3 Not > 10% 33% 1 audit every year by someone within the practice other than the person responsible for QA 1 audit every 3 years by someone external to the practice The quality of panoramic radiographs in a sample of general dental practices. Rushton VE, Horner K, Worthington HV. BDJ (12):630-3 Remit To produce selection criteria which are specific to dental radiography. These criteria should encompass all aspects of radiological practice in dentistry, with a focus on primary dental care 20

21 Justification is both ethical and legal requirement Training 16, 17, 18 Reporting 7 Dentists responsible for CBCT facilities should undergo a period of additional theoretical and practical training that has been validated by an academic institution (University or equivalent). Where national specialist qualifications in DMFR exist, the design and delivery of CBCT training programmes should involve a DMF Radiologist CBCT images must undergo a thorough clinical evaluation ( radiological report ) of the entire image dataset If is has been imaged it must be reported on! JM Reporting 19 Dento-alveolar CBCT images Radiological report should be made by a specially trained DMF Radiologist or, where this is impracticable, an adequately trained general dental practitioner Reporting 20 Craniofacial CBCT images Radiological report should be made by a specially trained DMF Radiologist or by a Medical Radiologist 21

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