Radiology and Radiography (2036DOH)

bruh idk what even to dooo

what is radiology?

the specialty concerned with radiation for the diagnosis and management/prediction of disease

bitewing radiographs are also known as…

interproximal radiographs

what is a periapical radiograph?

x-ray that includes the tooth from root to tip

what are the two techniques for the periapical radiograph?

1. paralleling technique

2. bisecting angle technique

what is an x-ray?

a form of electromagnetic radiation with a short wavelength that can cause ionisation and penetrate through solids

what are some characteristics of an x-ray itself?

• high energy waves

• no mass

• neutral charge

• travels at the speed of light

• invisible

• travels in a straight line

• can’t be focused into one point

• causes fluorescence

• harmful to living tissue

what is ALARA? (IMPORTANT)

• as limited as reasonably achieved

• term used for radiation safety

along with ALARA (radiation safety), what are some other key areas to consider when taking a radiograph?

• infection control

• radiographic technique (knowledge and accuracy = correct technique)

name a federal body that regulates radiation

• Australian radiation protection and nuclear safety agency: radiation protection in dentistry

why are radiographs essential in dentistry?
IMPORTANT WILL SHOW UP IN EXAM

• for diagnosis

• treatment planning (eg caries, perio disease, cyst, cracked tooth)

• monitoring (bone graft progression, edodont treatment etc)

no exposure to x-rays can be considered completely risk free, so the use of radiation by dentists is accompanied by…

a responsibility to ensure appropriate protection

no dental examination is complete without…

• dental radiographs

an intraoral full-mouth examination may or may not involve ________ and ________ radiographs based on your judgement for the patient treatment management

• periapical

• bitewing

______ ____ + _________ _______ → ________ → ________

• clinical exam

• radiographic imaging

• diagnosis

• treatment

list some indications for taking a radiograph

IMPORTANT WILL SHOW UP IN EXAM

• primary dental caries

• recurrent dental caries

• periodontal disease

• periapical lesions

• endodontics (root canal)

• extraction/lesions in bone

advantages of taking periapical radiographs

IMPORTANT WILL SHOW UP IN EXAM

• shows entire tooth from top of occlusal surface to 2/3mm below root

• shows bony contour (if bone loss in perio disease eg)

describe the bitewing radiograph

IMPORTANT WILL SHOW UP IN EXAM

• shows the upper and lower teeth in occlusion and the interproximal crestal bone view

• good for detecting interproximal caries

• also shows crestal bone loss

• also shows defect in margins

what does OPG stand for and describe it’s benefit

• orthopantomograph

• overall status of pt (with age, gender)

what is the bitewing radiograph used for?

• examining interproximal surfaces of teeth

• useful for detection of dental caries/alveolar bone levels/restoration contours

flip over for anatomical structures found in a bitewing image

radiolucency = __________

• demineralisation

• radiolucency is the darkening in an x-ray

radiopacity = ____/________ _____

• crown/amalgam filling

• radiopacity means the lighter colour

photostimulable phosphor plates (PSP) - how is the image captured and what sizes are available

• image captured on the plate is analog info - then converted to a digital format when the plate is processed - INDIRECT IMAGING TECHNIQUE

• 2 sizes, 1 (child), 2 (adult)

describe the PSP components

• polyester base coated with crystalline halide emulsion that converts X-radiation into stored energy

• energy in the crystals is released as blue fluoro light when PSP is scanned with helium-neon laser beam

the PSP has two sides, the tube and the tongue side. describe the tube side

• white/blue colour (lighter colour)

• always faces the radiation source (tube head)

what do receptor holders/positioners do?

• hold image receptor in place for exposure in intraoral radiographs

• point of entry for the central ray should be in the middle of the image receptor

pt position for bitewing

• head supported against the headrest

• occlusal plane parallel to floor

• mid-sagittal plane perpendicular to the floor

describe horizontal angulation

• directing x-ray beam through interproximal spaces

• must be positioned parallel to teeth of interest so central ray will also strike the image receptor perpendicularly

• if central ray not directed through contacts, overlap of premolar/molar contacts occurs (want to prevent this)

vertical angulation for bitewing in degrees

• 5-8 degrees either way on actual x-ray machine (one mark after 0)

• basically controls height (want top and bottom crowns and alveolar crests in one shot)

basic principles of bitewing

• film placed parallel to crowns (on biting surface)

• x-ray beam directed through contacts of teeth

• patient bites on bitewing tab or film holder

steps for bitewing

• receptor placed inside mouth (parallel to crowns of max and mand pos teeth)

• pt stabilises receptor by biting on tab/bitewing holder

• central ray of x-ray directed through contacts of pos teeth and at 5-8 degree vertical angle

what can be used to stabilise tab/bitewing holder in edentulous areas?

• cotton rolls

• tab can also be moved forward/back on film to get better support

on a premolar bitewing, the contact between the ______ and the ____ ______ should be clearly visible

• canine

• first premolar

describe positioning of molar bitewings

• centred on 2nd premolar + 1st molar (horizontal) perpendicular to contact between 1st and 2nd molar

• PSP shouldn’t be too far back (focus on edentulous area - waste of exposure)

correctly exposing intraoral receptors has 4 basic steps. list them

1. receptor placement

2. vertical PID (cone) angulation

3. horizontal PID (cone) angulation

4. centring of central ray

are the sensor plate holders for bitewing and periapical paralleling technique the same? why or why not?

• not the same

• bitewing is more flat

• paralleling is rounded shape

describe the peri-apical image and its purposes

• shows entire crown and root from occlusal surface/incisal edge to 2-3mm below root to show periapical bone

• gives vital info in diagnosis of most common dental diseases: caries, tooth apical lesions, perio bone loss, teeth fractures and bone anatomy

• used to diagnose pathologic conditions of the tooth, root and bone and tooth formation and eruption

• essential in endodontic and oral surgery procedures

what are the 2 techniques for periapical x-rays?

1. paralleling

2. bisecting

periapical radiographs can be taken to examine only….. or they may be prescribed as a…. which is ____

• selected areas

• full mouth series of radiographs

• rare

for periapical radiographs, where should the ‘a’ on the sensor plate be ideally positioned?

• at the crown end of the scan - wont get in the way of what you want to see at the root

principle 1 of 5 of radiography

• x-rays should be emitted from the smallest source of radiation as possible

principle 2 of 5 of radiography

• the x-ray source-to-object distance should be as long as possible (PID - position indicating device - fancy for the cone)

principle 3 of 5 of radiography

• the object-to-receptor distance should be optimised based on the procedure

• keep in mind technique and positioning for this

principle 4 of 5 of radiography

• the receptor and long axis of the tooth should be parallel to each other

• for parallel technique!

principle 5 of 5 of radiography

• the x-ray beam should be directed perpendicular to the tooth and receptor

functions of long cone (PID)

• beam alignment/angulation

  • vertical

  • horizontal

  • point of entry

  • centring exposure field

subcategories of horizontal and vertical angulation

• vertical

  • positive

  • negative

• horizontal angulation

positive angles of the PID is generally used for …. and …., and a negative angle is used for …

• bitewing exposures

• periapical exposures of the maxilla

• periapical exposures of the maxilla

zero angulation is achieved when…

• the long axis of the PID is directed parallel to the floor

positive angulation is when the PID is pointed….

negative angulation is when the PID is pointed…

• toward the floor

• toward the ceiling

(for parallel technique) the instruments used to hold the film parallel to the teeth are…

• plastic bite-blocks (Rinn XCP)

• indicator rods

• plastic locator rings

what do receptor holders/positioners do?

• hold the image receptor in place for exposure for intraoral radiographs

the point of entry for the central ray (paralleling technique) should be…

• in the middle of the image receptor

describe the film placement within Rinn XCP holder

• stabilises sensor plates in the holder and position behind teeth of interest

• place sensory plates parallel to long axes of teeth

• stabilise holder against occlusal surfaces of teeth being radiographed (two point contact)

location of apices for maxillary and mandibular teeth

• max: a-t line

• mand: 1 inch, above inferior border of mandible

central ray point of entry for different teeth

• central/laterals - side of nose

• canine - side of nostril flap (ala of nose)

• premolar - perpendicular line from pupil

• molar - outer corner of eye

basic rules of the paralleling technique

• position sensor plate so it covers the teeth, parallel to the long axis of the tooth

• plate should be placed in rinn xcp holder - and have pt bite on the bite block of the holder

• centre x-ray beam on sensor plate to ensure all areas of the plate are exposed

• vertical angulation - central ray of x-ray beam perpendicular to the film and long axis of the tooth

• horizontal angulation - direct the central ray of the x-ray beam through the contact areas between the teeth

anterior films are always placed _______

posterior films are always placed _________

identification letter ‘a’ on the film is always placed…

always the place the film parallel to…

• vertically

• horizontally

• in the slot of the film holder (dot in the slot)

• long axis of the teeth

for paralleling technique, the teeth must be in contact with…

• the bite block

• make sure pt doesn’t just close lips tight around bite block and not bite

for posterior films, the film should be equidistant from the…

• teeth in an anterior-posterior direction

advantages of paralleling technique

• decreased primary beam divergence

• less exposure to pt

• less penumbra (shadow/blurring)

• less dimensional accuracy

• no superimposition of other anatomical structures - central beam perpendicular to long axis of molars

• reduces exposure to thyroid gland and lens of eye (not in path of primary beam)

• easier to standardise

• pt doesn’t have to be positioned (supine fine)

when is the bisecting angle technique used/recommended?

• alternative to paralleling for taking peri-apical images

• paralleling technique recommended for routine peri-apical radiography but sometimes difficult due to pt anatomy (like small mouth) / lack of co-operation

the intra- oral peri-apical exposure with bisecting angle techniques can use _______ or ______ ______ to stabilise the film in position

• holders

• patient finger

where the the bisecting plane? and the angle formed by? x-ray central beam?

• halfway between plane of dental film and long axis of tooth

• angle formed by long axis of teeth and plate is bisected!

• central ray should be directed perpendicular to bisecting plane (90 degrees)

flip over for bisecting plane image

• the central ray meets the bisector angle (dotted line) at a 90 degree angle

the ______ angulation remains the same whether you are using the paralleling or the bisecting technique

• horizontal

describe the correct horizontal angulation of the central ray for the bisecting angle technique and what happens if it is incorrect

• central ray 90 degrees to curvature of arch and through contact areas of teeth

• if incorrect: overlapped contact areas, can’t be used to examine the interprox.

does the vertical angulation differ based on technique used? if so, which techniques and how?

PARALLELING

• vertical angulation of central ray is perpendicular to film and long axis of tooth

BISECTING

• vertical angulation directed perpendicular to imaginary bisector

what happens if the vertical angulation is incorrect vs correct?

• incorrect: image isnt same length as tooth (longer or shorter)

• correct: image same length as tooth

• shorter image happens when angle is too large and vice versa for longer image

flip over for head position for bisecting angle technique

advantages of bisecting angle technique

1. more comfy: film placed in mouth at angle to long axis of tooth, sensor doesnt rlly touch the tissues as much

2. sensor holder isnt needed - pt can hold using finger

3. sensor can be angled to accommodate different anatomies (no anatomical restrictions)

4. good for when paralleling cant be used (like if pt has smol mouth or low palatal vaults

disadvantages of bisecting technique

1. increased exposure to radiation so should only be used when necessary

2. superimposition of anatomical structures in the image

3. more chance of distortion (bc film and teeth arent parallel)

4. harder to position x-ray beam - bc ring not used so difficult to visualise where it should be directed

5. film less stable when pt uses finger - more chance of moving

6. more chance of being a short/long image so not easy to reproduce image for review

anatomical situations that interfere with radiography

• shallow palate

• large palatal torus

• shallow/tender floor of moth

• short lingual frenum (tongue tie)

similarities between BSA and paralleling

• horizontal angulation

• film positioning in arch

• alignment of central ray to cover film

preparation for BSAT

• prepare operatory with infection control barriers

• turn on x-ray machine and check basic settings

• discuss wtith pt - med history and area of concern

• determine no. + type of images to be exposed

• inform pt of procedure

positioning the pt for BSAT

• seat pt comfy in the chair - back upright and head supported

• ask pt to remove glasses and bulky earrings

• have pt remove pros

• drap pt with lead apron + thyroid collar

• wash hands and put on clean exam gloves

• proceed with radiographic technique

what type of film holder can be used for the BSAT?

anterior: finger

posterior: snap ray holder

what are some variables you need to consider to produce quality dental radiographs?

• knowledge and attention to methods of exposing dental x-ray film, digital sensors within oral cavity

• using appropriate technique

• setting radiation exposure variables

• positioning pt properly

• selecting suitable size of PSP/digital sensor

• finding out how receptor is to be positioned/held in place

list some errors that may occur when taking a radiograph

• pt prep errors

• PID angulation/positioning errors

• sensor placement

describe the pt prep error

• should always explain procedure to pt and tell pt clearly what they can do to help get a quality image and avoid retakes and unnecessary exposure

• most common error is movement

• factors that contribute to this: discomfort, unsupported head position, gagging/swallowing, or pt disability

describe the operator position error

• if you have incorrect position of the tube head you might get elongation or shortening of the image (vertical angle bad)

• superimposition (if horizontal angle bad)

• cone cut - psp plate not exposed bc not correlating with the cone

when does elongation happen in the BSAT and the paralleling technique?

• note: generally for vertical angulation

BSAT

• under angulated or too shallow relative to bisecting plane

paralleling

• vertical angulation not perpendicular to long axis of teeth

when does foreshortening of the radiographic image happen?

• if PID over-angulated (too steep) relative to bisecting plane