Radiography
Radiography
• Imaging method completing clinical examination of patients
Radiography
Principle:
X- ray radiation going through various materials (tissues) is absorbed.
The absorbtion causes
- image on the film
(a special suspension AgBr - silver bromide) Or
- image on the computer screen (sensor -semiconductor)
Radiography
• Roentgen tube - x- ray tube:
Cathode - Anode - Tension
Catode (heated) - emission of electrons -going against anode - strike - heat and x ray radiation originates . Wavelangth - 0,3 - 0,5 x 10-10 m
Roentgen tube X ray tube
The x-ray picture is monochrome - black and white Light areas - radioopaque (radioopacity) Dark areas - radiolucent (radiolucency)
Extraoral and intraoral radiography
• Extraoral:
The film is placed outside of oral cavity
- OPG (orthopantomograph^)
- Teleradiography
- Skull x-ray posteroanterior
- Skull x-ray half axial
- Skull x-ray side projection (TMJ,mandible)
- CT (computer tomography)
Extraoral and intraoral radiography
Intraoral - the film is placed into the oral Cavity - a special x-ray apparatus.
- Teeth
- Alveolar bone
- Periodontal space
- Fillings
- Caries
- Impacted teeth
- Level of endodontic treatment
Hold up of the tubus
• In vertical plane
• In horizontal plane
Vertical hold up
The size of the picture should conform
to the size of the tooth:
The vertical hold up of the tubus must be correct If yes:
the picture is isometric
If not:
the picture of the tooth is smaller- hypometric or
the picture of the tooth is bigger than the tooth - hypermetric
Parallel technique
The film or sensor is parallel to the long axis of the tooth. The picture is unbiased. The x-ray beam goes in right angle to the plane of the film as well as long axis of the tooth
Technique of halving angle:
Sometimes is impossible to put the film into the holder therefore the technique of halving angle must be used
Film is not parallel with the axis of the tooth.
There is an angle between this axis and the film. Central beam goes in right angle to the plane halving this angle
Technique of halving angle:
Alveolar bone and surrounding tissues
Film
-► The x-ray beam
_The angle between the x-ray beam
*and then plane halving the angle between the long axis of the tooth and the film.
The long axis of the tooth
The tooth
The angle
between the long axis of the tooth and the film
Hypometric and hypermetric picture
Hypometric picture: the picture of the tooth is smaller in comparison to real size the x-ray beam goes in right angle to the tooth
Hypermetric picture : the picture of the tooth is bigger than the tooth The y-ray beam goes in right angle to the film
Intraoral radiography
• Apical projection: the central beam goes through the apex area
• Periodontal projection: the central beam goes through the uper third of the root
• Coronal projection: the central beam goes through the crown.
Orthoradial and excentric projection
• Orthoradial - the central beam goes parallel to interdental septa
• Excentric - goes from distal or mesial
Bitewing
	
	
Hi	M
The film or sensor in special holder, with bite plate, the x-ray beam goes parallel to the interdental septa, upper and lower crowns of teeth can be seen -esp. proximal surfaces. Early stages of dental caries can be recognised and also surrounging alveolar bone can be well seen.