intro to radiology Flashcards
radiation dose Vs diagnostic benefit
need for information - cannot get in other way
radiation dose
diagnostic yield/benefit - know what you want to get so no unnecessary harm
principles of radiation protection
justification
optimisation - ALARA, ALARP
dose limitation
- for radiation workers and members of the public, not patients
ALARA
as low as reasonably achievable
ALARP
as low as reasonably practicable (now, inc financial constraints)
how safe are X-rays
there is a pt information leaflet , can give out
4 components needed in production of radiographic image
source of X-rays
object
image receptor
processing - conversion of latent image to permanent visible image
source of X-rays
X-ray machine
object in dental X-rays
teeth and jaws
- interaction of X-rays with matter
image receptor in dental X-rays
digital receptors
- direct - panoramic on level 3 and 5, also for endo in op tech on level 2
- indirect - intra orals on level 3 radiololgy
Xray film packets (intra oral)
screen film combinations
operation of X ray machines
use domestic electricity supply - not enough to make X-rays
converts to high voltage
dental machines potential - range of 60 to 70 kV
- panoramic higher (kilo [electron] Volts)
X rays properties
cannot be sensed by person
electromagnetic radiation family
straight line from point of origin, but is also a diverging beam
thus area at end point is larger the further away you travel from the source
- inverse square law
photographic interaction with matter - no effect E.g. air - complete absorption e.g. metals (amalgam and gold) - absorption and scatter white image created useful as makes image but transfer energy to pt
no effect photographic interaction of X rays with object
appear black
e.g. air
complete absorption photographic interaction of X rays with object
almost white
e.g. metals, amalgams
absorption and scatter photographic interaction with object
white-grey image made
makes image
but transfer energy to pt
what is a radiographic image
pictorial representation of a part of the body
a record of the pattern of attenuation * of the X-ray beam after it has passed through matter
- shades – almost white to black (complete absorption to lesser extent/no absorption)
3 classes of dental radiographic views
intra oral
extra oral
cone beam CT (CBCT)
3 types of intra oral X ray
bitewings
periapicals
occlusals
2 extra oral dental Xrays
panoramic (DPT/DPR/OPT)
cephalometric
cone beam CT X ray
cross sectional 3D imaging - very thin slices
bitewing radiograph
side teeth (premolars and molars)
symmetry of upper and lower teeth
minimal overlap of adjacent teeth ***
- reach dentine enamel junction – miss proximal caries
inter-dental bone
bitewing radiograph demonstrates
upper and lower crowns of one side
mesial first premolar contact to most distal
contact point or surface
minimal, overlap of teeth
enamel-dentine junction
coronal pulp morphology
interdental bone
bitewing radiograph key points
shows upper and lower cheek teeth of one side
from distal of canine posteriorly, to include all contact points
take R and L
one per side unless all premolars and molars present
pathology seen in bitewing radiographs
(inter)proximal caries
cervical caries
occlusal, buccal & lingual caries
restorations: ledges, defects
interdental bone changes
periapical radiograph
shows the full length of at least one tooth
peri = around
apical - the apex or tip of the tooth
surrounding anatomical features
pathology seen in periapical radiograph
crown - caries, trauma, other non-carious tooth surface loss
changes related to restorations
pulpal pathology
root
supporting bone
occlusal radiograph types
oblique
- similar to large periapical
- Catch details not shown on normal periapical (unerupted additional tooth and pathological lesion)
true
- cross sectional
- plain view of a section of the mandible of floor of mouth
film packet on occlusal plane
panoramic radiograph
Dental panoramic radiograph DPR
Full view of dentition
An image of a layer, not full thickness of all structures between X-ray source and image receptor
cephalometric radiograph
View of facial bones to enable measurements of dental and skeletal relationships
Usually lateral view (true lateral)
Includes soft tissue profile
- Unusual
- Use special technique
