Basic guide to dental radiography

Basic Guide to Dental Radiography provides an essential introduction to radiography in the dental practice. Illustrated throughout, this guide outlines and explains each topic in a clear and accessible style. Comprehensive coverage includes general physics, principles of image formation, digital image recording, equipment, biological effects of x-rays and legislation Suitable for the whole dental team Illustrated in full colour throughout Ideal for those completing mandatory CPD in radiography Useful study guide for the NEBDN Certificate in Dental Radiography, the National Certificate in Radiography or the Level 3 Diploma in Dental Nursing Title Page 5 Copyright Page 6 Contents 9 Acknowledgements 10 Chapter 1 General physics 11 ATOMS AND MOLECULES 11 ENERGY 15 ELECTRICAL ENERGY 17 ELECTRIC CURRENT 19 Chapter 2 X-ray production 22 X-RAY TUBE FILAMENT 22 TRANSFORMERS 23 X-RAY TUBE ANODE 25 VOLTAGE RECTIFICATION 25 HALF-WAVE AND FULL-WAVE RECTIFICATION 26 THE PROCESS OF X-RAY PRODUCTION 27 BREMSSTRAHLUNG (CONTINUOUS) SPECTRA 30 PRODUCTION OF LINE SPECTRA 31 FACTORS AFFECTING THE NUMBER OF X-RAY QUANTA PRODUCED 32 THE PROPERTIES OF X-RAYS 33 Chapter 3 X-ray interaction with matter 37 FACTORS AFFECTING ATTENUATION 39 Chapter 4 Principles of image formation 46 IMAGING GEOMETRY 46 THE IDEAL IMAGING SYSTEM 48 EFFECT OF NONPARALLEL RELATIONSHIP 51 DIFFERENTIAL ABSORPTION 51 Chapter 5 Imaging with dental X-ray film 56 DENTAL X-RAY FILM 56 THE CONSTRUCTION OF DENTAL FILM 57 FILM EMULSION 58 FILM CHARACTERISTICS 60 Characteristic curve of a film 60 FILM SPEED 61 FILM CONTRAST 61 Film contrast characteristics 62 FILM LATITUDE 62 Film (latitude) characteristics 63 CONTRAST AND SPEED 63 FILM PROCESSING 64 DEVELOPER 64 Developing faults 66 FIXER 68 Fixer faults 68 WASHING 69 Washing faults insufficient washing 69 DRYING THE FILM 69 Manual processing 69 Chapter 6 Digital imaging recording 71 TYPES OF DIGITAL IMAGE RECORDER 71 Phosphor plates 71 Charge-coupled devices 75 DIGITAL IMAGE RECORDING ADVANTAGES 76 DIGITAL ANALOGUE DETAIL COMPARISON 77 DIGITAL IMAGE DENSITY MANIPULATION 77 CONTRAST MANIPULATION 78 Chapter 7 X-ray equipment 80 INTRA-ORAL 80 DENTAL INTRA-ORAL TUBE HEAD 80 Tube exit port detail 80 Mineral oil 82 Technical features 82 ORTHOPANTOMOGRAPHY 83 Fulcrum points for mandibular tomography 86 Tomographic imaging movement for OPTs 87 Chapter 8 Radiation doses and dose measurement 88 UK POPULATION RADIATION DOSE 88 Medical and dental exposures 89 DOSE MEASUREMENT 89 TYPES OF DOSE METERS 90 THIMBLE IONISATION DOSE METER PICTURE 90 Thermoluminescent dose meter: Thimble chamber 91 Thermoluminescent dose meter 91 READING A TLD RECORD 92 DOSE QUANTITIES 93 Radiation exposure 93 Absorbed dose 93 Dose equivalent 94 Chapter 9 Biological effects of X-rays 96 INDIRECT EFFECTS OF RADIATION DOSES 97 DIRECT BIOLOGICAL EFFECTS OF RADIATION DOSES 98 STOCHASTIC EFFECTS OF RADIATION EXPOSURE 100 DETERMINISTIC OR NON-STOCHASTIC EFFECTS 100 WHO WILL BE AFFECTED 101 DETRIMENT WITH AGE AT EXPOSURE 101 DOSE REDUCTION FOR PATIENTS 102 DOSE REDUCTION FOR STAFF 103 Chapter 10 Legislation: Ionising Radiations Regulations 1999 (IRR 1999) 104 IONISING RADIATIONS REGULATIONS 1999 (STATUTORY INSTRUMENT 3232) 104 Notification of specified work 105 Risk assessment 105 Restriction of exposure 107 Personal protective equipment 107 Dose limitation 108 Contingency plans 109 Radiation protection advisors (RPA) 110 Information and training 111 Designation of controlled areas 111 Controlled areas at below and above 70 kV 111 Advised safe standing area 113 Other consideration for controlled areas 113 Mains isolators 114 Operator’s position 115 Local rules and radiation protection supervisors 115 Radiation protection supervisors 116 Duties of manufacturers 116 Equipment for medical use 116 Chapter 11 Legislation: Ionising Radiation (Medical Exposures) Regulations 2000 (IR(ME)R 2000), Statutory Instrument 1059 118 DUTIES OF THE EMPLOYER 119 DUTIES OF THE PRACTITIONER, OPERATOR AND REFERRER 120 JUSTIFICATION OF MEDICAL EXPOSURES 121 Optimisation 121 Clinical audit 122 Justification 122 Optimisation 123 EXPERT ADVICE 123 TRAINING 123 Chapter 12 Quality assurance 124 STAFF TRAINING 125 FILM STORAGE 126 Ideal film storage conditions 126 Charge coupled devices 127 FILM HOLDERS 127 CASSETTES 128 FILM PROCESSORS 130 Cleaning 130 Temperature 130 CHEMICAL LEVELS 131 Chemical activity 131 Performing the stepped-wedge test 132 Setting up a stepped-wedge test 132 DARKROOM TESTING 133 Setting up the safelight test 134 X-RAY EQUIPMENT QUALITY ASSURANCE 136 Physical checks 136 Electrical safety 136 Radiation safety 137 Chapter 13 Dental intra-oral paralleling techniques 138 PERFORMING THE EXAMINATION 139 INTRA-ORAL PARALLELING TECHNIQUES 140 General rule for positioning film holders 141 THE FILM HOLDERS 141 EXAMPLES OF FILM HOLDERS 142 ASSEMBLING THE FILM HOLDERS 143 THE FILM 143 THE CENTRAL RAY 144 PLACING THE HOLDERS INTO THE PATIENT’S MOUTH 144 UPPER ANTERIOR FILM HOLDER PLACEMENT 144 APPEARANCE OF AN IMAGE OF THE UPPER CENTRAL INCISORS 146 LOWER ANTERIOR FILM HOLDER PLACEMENT 147 UPPER POSTERIOR HOLDER PLACEMENT 149 LOWER POSTERIOR HOLDER PLACEMENT 151 ASSESSMENT OF THE IMAGE 153 RADIOGRAPHIC ASSESSMENT 153 Area 153 Projection 154 ASSESSMENT OF THE VERTICAL ANGLE 155 THE IMAGE 156 ASSESSING THE MESIODISTAL (LATERAL) ANGLE 158 DENSITY ASSESSMENT 160 CONTRAST ASSESSMENT 160 SHARPNESS ASSESSMENT 161 ARTEFACTS 162 BITEWING RADIOGRAPHS 163 BITEWING RADIOGRAPHS: PLACING THE HOLDER INTO THE MOUTH 163 CENTAL LONG-AXIS POSITION FOR BITEWING RADIOGRAPHS 165 ASSESSING THE BITEWING IMAGE 167 Area 167 Projection 167 Density 168 Contrast 168 Sharpness 168 Artefacts 168 Grading 168 Chapter 14 Orthopantomography 169 PERFORMING THE EXAMINATION 169 OPG IMAGE ASSESSMENT 171 Area 171 Projection 172 FRANKFORT PLANE ASSESSMENT 172 MEDIAN SAGITTAL PLANE ASSESSMENT 173 FOCAL TROUGH ASSESSMENT 176 Density 178 Contrast 178 Sharpness 179 Artefacts 179 Chapter 15 Other dental radiographic techniques 180 BISECTING ANGLE PERIAPICAL RADIOGRAPHS 180 Positioning the film 181 The central ray in bisecting angle 182 Bisecting angle guide to central ray positioning 183 Assessment of the bisecting angle image 183 OCCLUSAL RADIOGRAPHS 186 Standard positioning for the upper central occlusal image 187 Upper oblique occlusal imaging 188 Positioning for lower occlusal radiographs 190 Positioning for infero-superior occlusal imaging 190 CEPHALOMETRIC IMAGING 191 Positioning the patient for cephalometry 192 Central ray 192 Assessment of the cephalometric image 192 Lateral cephalometry image assessment 193 RARELY USED TECHNIQUES 195 Parallax projections 195 Lateral oblique mandible (dissociated laterals) 196 Lateral oblique mandible image 198 Appendix A: Adequate training 199 Further reading 200 Appendix B: Image quality troubleshooting 202 Index 211 EULA 218