16 Flashcards
o prevents secondary scatter
o lead films
o placed between the patient & film
Grid
Equipment preparation :
- Load the extraoral cassette in the dark room.
Place one extraoral film bet. Two intensifying screens and securely close the cassete - Set the exposure factors
PATIENT PREPARATION:
- Explain to the patients the procedure
- Place the lead apron without the thyroid collar
- Remove all objects from head and neck region
Film parallel to midsagittal plane
Lateral cephalometric
Canthomeatal line at 30 with film
Reverse towne
Cathomeatal line parallel to film
SUBMENTOVERTEX
Canthomeatal line at 37 with film
Waters
Cantomeatal line at 10 with film
Posterioranterior cephalometric
used to examine the posterior region of the mandible
LATERAL JAW RADIOGRAPHS
patients with limited jaw opening due to a fracture or swelling and in patients who have difficulty in stabilizing or tolerating intraoral film placement
LATERAL JAW RADIOGRAPHS
PURPOSE
→ evaluate impacted teeth, fractures, and lesions located in the body of the mandible
→ demonstrates the mandibular premolar and molar regions as well as the inferior border of the mandible
BODY OF THE MANDIBLE PROJECTION
PURPOSE
→ evaluate impacted third molars, large lesions, and fractures
RAMUS OF THE MANDIBLE PROJECTION
can be exposed using a standard intraoral x-ray machine but
most require the use of an extraoral unit and cephalostat
SKULL RADIOGRAPHS
→ used to examine the bones of the face and skull
→ most often used in oral surgery and orthodontics
SKULL RADIOGRAPHS
evaluate facial growth and development, trauma, and disease and developmental abnormalities
→ demonstrates the bones of the face and skull as well as the soft tissue profile of the face
LATERAL CEPHALOMETRIC PROJECTION
is a line extending from the top of the ear canal to the bottom of the eye socket.
The Frankfort plane
→ evaluate facial growth and development, trauma, and disease and development abnormalities
→ demonstrates the frontal and ethmoid sinuses, the orbits, and the nasal cavity
POSTEROANTERIOR PROJECTION
→ evaluate the maxillary sinus area
WATERS PROJECTION
→ identify the position of the condyles, demonstrate the base of the skull, and evaluate fractures of the zygomatic arch
→ demonstrates the sphenoid and ethmoid sinuses and the lateral wall of the maxillary sinus
SUBMENTOVERTEX PROJECTION
if the zygomatic arch is the area of interest, the exposure time is reduce to approximately one-third the normal exposure time
SUBMENTOVERTEX PROJECTION
identify fractures of the condylar neck and ramus area
REVERSE TOWNE PROJECTION
FILM PLACEMENT
cassette placed flat against the patient’s ear and centered over TMJ
TRANSCRANIAL PROJECTION (LINDBLOM TECHNIQUE)
PURPOSE
→ evaluate the superior surface of the condyle and the articular eminence
→ also used to evaluate movement of the condyle when the mouth is opened and to compare the joint spaces (right vs. left)
TRANSCRANIAL PROJECTION (LINDBLOM TECHNIQUE)
film and x-ray tubehead are moved in opposite directions around a fixed rotation point
o the location of this rotation point determines what plane of
the head will be imaged
TEMPOROMANDIBULAR JOINT TOMOGRAPHY
requires a special x-ray unit, such as the Quint Sectograph
TEMPOROMANDIBULAR JOINT TOMOGRAPHY
→ provides the most definitive imaging of the bony components of the TMJ
o the condyle, articular eminence and glenoid fossa can all be examined on a radiograph known as the tomogram
TEMPOROMANDIBULAR JOINT TOMOGRAPHY
→ produce a much better picture of lesions or fractures
CONE BEAM COMPUTED TOMOGRAPHY
refers to the measurement of ionization in air produced by x-rays
EXPOSURE
measures the intensity of the radiation field as opposed to the amount of radiation absorbed
EXPOSURE
the amount of energy absorbed by a tissue
DOSE
measures the total energy absorbed by any type of ionizing radiation per unit of mass of any type of matter
Dose
varies with the type and energy of radiation and type of matter absorbing the energy
Dose
measurement used to compare the biologic effects of different types of radiation
DOSE EQUIVALENT
unit of electrical charge; the quantity of electrical charge transferred by 1 ampere in 1 second
Coulombs
unit of electrical current strength; current yielded by 1 volt against 1 ohm of resistance
Ampere
unit of energy equivalent to 1.0 x 10^-7 joules or to 2.4 x 10^-8 calories
Erg
SI unit of energy equivalent to the work done by the force of 1 newton acting over the distance of 1 meter
Joule
SI unit of force; the force that, when acting continuously on a mass of 1 kg, will impart to it an acceleration
Newton
unit of mass equivalent to 1000 grams or 2.205 pounds
Kilogram
