Radiology: Radiology An Introduction


Learning Objectives: Learning Objectives List the Properties of X-rays Understand the need for radiology Explain Radiation Protection


Introduction: Introduction Discovery of the x-ray X-ray picture/ roentgenograph/radiograph


Radiation, Radiology and Radiography: Radiation, Radiology and Radiography Radiation = Emission of energy in the form of EMR or particulate radiation. Radiography = the techniques involved in producing radiographs. Radiology = interpretation of radiographs and other images.


Dental Radiology: Dental Radiology Dental exams one of most common 1997-8 survey in UK found: 19 million intra-oral radiographs taken 2.9 million panoramic radiographs taken In Sweden 15 millions/y


Properties of x-rays: Properties of x-rays Invisible Have no charge Travel at speed of light Have no mass or weight Travel in straight lines


Properties of x-rays: Properties of x-rays Can cause ionization Can affect photographic film emulsion Can affect living tissue


Properties of x-rays: Properties of x-rays Can penetrate opaque tissues and structures Radiopaque (light) Radiolucent (dark)


Conventional Radiography and Digital Imaging: Conventional Radiography and Digital Imaging Conventional radiography uses radiographic film as the image detector/sensor.


Conventional Radiography and Digital Imaging: Conventional Radiography and Digital Imaging Digital imaging uses a charged coupled device (CCD) as the image detector/sensor.


Advantages of digital imaging: Advantages of digital imaging No use of films, intensifying screens, cassettes etc. Computer hardware and software allows you to view and store images. Multiple images are obtained without changing film holder or using new film. Less exposure to radiation


Why do we take radiographs?: Why do we take radiographs?


Role of radiographs: Role of radiographs Clinical examination phase Diagnosis (confirm / exclude) Treatment planning During treatment Follow up after various treatment procedures


Are all radiographs necessary?: Are all radiographs necessary?


Slide15: Must justify taking any radiographs; not a blanket screening for all patients. Radiographs do have limitations and should never replace a thorough clinical examination. There are disadvantages and risks - must weigh up benefits against risks. Radiographs can indicate the need for further investigation.


The uses of radiographs: The uses of radiographs


General dentistry:: General dentistry: Loss of tooth structure Carious (occlusal, proximal) Non - carious (attrition, abrasion, erosion, fracture) Periodontal disease Endodontic disease Impacted teeth Trauma (root and alveolar fractures, foreign bodies) Other pathology affecting bone


Periodontics:: Periodontics: Alveolar bone height Alveolar bone health Generalised vs localised alveolar bone loss Peri-radicular infection


Orthodontics:: Orthodontics: General growth and development Delayed eruption Ectopic teeth Eruption paths Impacted teeth Supernumerary teeth


Oral medicine and oral surgery:: Oral medicine and oral surgery: Extractions Jaw fractures Tumours Infections Foreign bodies


Endodontics:: Endodontics: Anatomy of the pulp chamber and canal (s) Presence of peri-radicular and peri-apical pathology Resorption of roots Dental trauma Canal length determination Root filling Follow-up/monitor healing (periapical, fracture, resorption)


Radiology: Radiology 3 common dental X-rays: Bitewings Periapical Panoramic (Univ. Manitoba, 2005)


Types of Radiographs: Types of Radiographs Intra-oral Extra-oral Other technologies/imaging modalities


Intra-oral radiography: Intra-oral radiography Radiographic film/detector is exposed whilst inside the patient’s mouth Image of a small area - a few teeth and adjacent supporting structures


Bitewing:: Bitewing: Indications: baseline examination detection of: - dental caries - non-carious tooth loss - monitoring the progress of any loss of tooth structure - assessing existing restorations (defects, contacts) - assessment of periodontal status.


Periapical:: Periapical: Indications: detection of apical infection/inflammation dental trauma (to the tooth and associated alveolar bone) assessment of root morphology endodontic diagnosis, planning, treatment and monitoring


Occlusal:: Occlusal: Indications: presence/absence of developing teeth supernumerary teeth impacted teeth pathology not fully demonstrated in an intraoral view contour of buccal and lingual cortical plate localisation technique (used with another film) when unable to take intra-oral radiographs - limited opening of mouth - uncooperative child.


Occlusal:: Occlusal:


Extra-oral radiography: Extra-oral radiography Radiographic film/detector positioned outside the patient’s mouth. Can image larger areas of the mandible and maxilla, face, skull.


Extra-oral radiography: Extra-oral radiography Skull radiographs: lateral head


Extra-oral radiography: Extra-oral radiography anterio-posterior view lateral oblique jaw


Extra-oral radiography: Extra-oral radiography TMJ


Extra-oral radiography: Extra-oral radiography Tomography Panoramic radiograph orthopantomograph (OPG) TMJ maxillary sinus views Modern OPG machines can do a range of skull views by altering the extent of the tomographic layer used and by altering the shape of the tomographic layer used


Indications for traditional OPG: Indications for traditional OPG Assessment of - wisdom teeth - TMJ pathology - maxillary sinus - jaw bone pathologies - orthodontic diagnosis - jaw bone fractures.


Other Technologies and Imaging Modalities: Other Technologies and Imaging Modalities Computerised tomography (CT) Magnetic resonance imaging (MRI) Ultrasound


Computerised tomography (CT): Computerised tomography (CT) Radiographic cutting of a region/structure into thin slices Fairly high doses Good diagnostic information Used in oral maxillofacial surgery (diagnosis and treatment planning of tumours, fractures and neuropathies)


Magnetic resonance imaging (MRI): Magnetic resonance imaging (MRI) Gives better soft tissue images than CT scans No radiation - uses magnetic field and sound waves Very good diagnostic information Used in oral maxillofacial surgery (diagnosis and treatment planning of tumours, fractures and neuropathies, gold standard for TMJ imaging)


Ultrasound: Ultrasound Limited uses for dental care Salivary gland tumours Possibly TMJ Locating foreign object in soft tissue Soft tissue cysts


Radiation Units: Radiation Units Exposure Absorbed dose Dose Equivalent


Radiation Units: Radiation Units Exposure: amount of radiation in a beam of x-rays ionization in air Coulomb per kg


Radiation Units: Radiation Units Absorbed dose: amount of radiation absorbed by the tissues amount of energy deposited in 1 kg Gray, Gy (1 joule/kg) Rad (radiation absorbed dose) equal to 0.01 J/kg


Radiation Units: Radiation Units Dose Equivalent: amount of radiation absorbed by the tissues x Quality Factor (QF) QF relates to biological damage Sievert, Sv equals 1 Gy


Radiation Protection: Radiation Protection Good technique to avoid re-takes: use of correct film for the view intended use of appropriate film holder correct film placement within film holder correct placement (angulation) of film holder in patient’s mouth correct tube angulation correct exposure time


Radiation Protection: Radiation Protection Protect patient, public and staff Remember dose is cumulative Benefit/risk ratio Dose reduction = time, distance, shielding High speed film Long exp. cable Lead coats to reduced exp. time so dentist steps away stop scatter radiation


Conclusion: Conclusion X-rays is essential in dentistry Dose is cumulative Follow radiation protection principles Each X-ray exam should be justified


References: References Whaites E (1996) Essentials of dental radiography and radiology, 2nd edition, Churchill Livingstone de Lrye and Johnson, Essentials of dental radiography for dental assistants Goaz and White, Oral radiology: Principles and interpretation, CV Mosby