Unit 314: Radiography Flashcards
LO1: Know the regulations and hazards associated with ionising radiation LO2: Understand the different radiographic films and their uses LO3: Understand the imaging process and the management of chemicals used for processing radiographs LO4: Understand the importance of stock control, mounting and quality assurance in dental radiography
Which regulation sets the requirement for a controlled area?
IR(ME)R 2000
Who must ensure all staff read the local rules?
RPS
Who can carry out the role of RPA?
Radiation Physicist
What is the purpose of intensifying screen within a cassette?
Fluoresce when sensitised by x-rays to reduce the radiation needed to expose the film
How are digital phosphor plates processed?
By scanning with a laser beam
What colour and wattage is the safelight?
Red, 15W
Why must safelights be used?
To protect the film from daylight
How would an x-ray film appear if it had been exposed to light before processing?
Black
What may cause an x-ray to get darker over time?
Insufficient fixing
Why should you use a funnel to refill the chemicals in an automatic processor?
To avoid splashing
Where should you dispose of paper towels that have been used to clean up chemical spillage?
Non-infectious hazardous waste (chemical)
Where is the best place to store unexposed extra oral films?
Refrigerator
Which regulations are concerned with patient safety?
IR(ME)R
Which regulations are concerned with staff safety?
IRR
Who is responsible for implementing radiation protection in the workplace under IR(ME)R?
RPS
What level of risk is associated with dental x-rays?
Low risk
Which radiograph is most suitable to use in root canal treatment?
Periapical
Name 3 extra-oral x-rays
Lateral cephalometric
Lateral oblique/skull
OPG/DPT
Name 3 intra-oral x-rays
Bitewing
Periapical
Occlusal
What is one of the most suitable uses for an occlusal radiograph?
To look for impacted upper canines
What are bitewing radiographs used for?
To check for interproximal caries on posterior teeth
What do periapical radiographs show?
One or two teeth including the whole root and crown
What are lateral cephs used for?
Orthodontic assessment and treatment planning
What do OPG/DPTs show?
The whole of both jaws
Which radiograph should be taken to diagnose widespread bone loss?
OPG/DPT
Where is the controlled area measured from?
The machine head
How big is the controlled area?
1.5m
What is the zone 2m away from the patient called when taking radiographs?
Safe zone
Which radiographs would be best used to detect impacted wisdom teeth?
Lateral oblique
OPG/DPT could also work
What are the advantages of digital dental radiogaphy?
Less radiation
Quicker processing
No chemicals
Can be emailed to other professionals
What are the stages and timings of manual processing?
Develop - 3-5 minutes
Rinse - couple secs
Fix - 6-10 minutes
Wash - up to 20 mins
What are the 4 stages of automatic processing in order?
Develop
Fix
Wash
Dry
In which method of processing are safe lights used to protect the image?
Manual
What are the possible causes if a processed film is too pale?
TOO LITTLE
under exposed
under developed
Cold developer
What temperature should the developer be at? (ideal temperature)
20C
What is the range of acceptable temperatures for chemicals used in x-ray processing?
18C - 22C
What are the possible causes if a processed film is too dark?
TOO MUCH
Over exposed
Over developed
Hot developer
Which fault may cause green or brown marks?
Spent chemicals
What fault may occur if the developed film is dried too quickly?
Crazed pattern
What faults may be caused by incorrect positioning or angling of the collimator?
Coned image
Cut-off image
Elongated image
Foreshortened image
What may cause blurring of an x-ray image?
MOVEMENT
The patient moved
The collimator/x-ray machine moved
Are lead aprons required in a dental practice?
No, the exposure is low risk and not aimed at any susceptible areas
Which radiograph would show a fractured neck of the condyle?
DPT/OPG
What are the disadvantages of digital radiography?
Sensors are bulky and rigid
Expensive
What is the role of the RPS?
To ensure compliance with the local rules
When may a dental nurse press the exposure button?
Following documented in house training and only under instruction by the clinician
Why is radiography especially dangerous?
Undetected by human senses
Where should the pimple be when mounting a radiograph?
Facing the operator
Why should the pimple always face the x-ray machine during exposure?
The lead foil on the other side would block the radiation if it placed the other way
What indicators can be used when mounting radiographs?
Pimple facing operator Smile line (curve up at sides) Molars towards the side (like in charting)
What may result from incorrect mounting of an x-ray film?
Incorrect diagnosis
Wrong treatment
Who formulates the contingency plans for if the x-ray equipment malfunctions?
RPA
Where should x-ray films be stored?
Cool, dry cupboard
Outside controlled area
Away from sources of radiations (x-ray machine, heaters, autoclave etc.)
What may cause fogging on an x-ray film?
Expired film (emulsion deteriorates)
Why is x-ray film stock rotated?
Oldest films are used first to avoid films expiring
What percentage of radiographs must be grade 3?
No more than 10%
What percentage of radiographs must be grade 1?
At least 70%
What percentage of radiographs must be grade 2?
No more than 20%
When are radiographs safe to be exposed to normal light?
After fixing
White crystal marks on a radiograph indicate which fault?
Insufficient washing after fixing (some chemicals still on film)
In the event of the x-ray machine malfunctioning the local rules will indicate where should the isolator switch is, which disconnects the electricity supply. Where should this information be displayed?
By the safety zone limit
Not in controlled area
As close to machine as possible
When should dosimeters be worn?
If there are 150 intraoral or 50 extraoral exposures in a week
Under IR(ME)R, the dose of radiation used should be in line with ALARP at all times. So the lowest dose is used at all times. What is the correct term for this concept?
Optimisation
When tooth tissue is exposed to an x-ray beam, they absorb the rays at varying levels. Which two terms are used to describe the amount of rays absorbed?
Radiolucent and radiopaque
Under IR(ME)R the benefit of exposing the patient to ionising radiation should be seen to outweigh the risk of causing tissue damage, before an x-ray is taken. Which term describes this?
Justification
Where on the body is the recommended position to place a radiation monitoring badge?
Waist area
Closest to vulnerable organs (reproductive)
How is the film packet angled when using a film holder?
Parallel to tooth
paralleling technique
What term describes the method used when the patient must hold the film packet in the mouth using a finger?
Bisecting angle technique
How would an acute periapical abscess appear on a radiograph?
Rounded black area at the apex
What is the order of the contents in an intra-oral film packet from the x-ray machine tube side?
Paper, film, paper, foil
What is the order of the contents in an extra-oral film cassette from the x-ray machine tube side?
Marker, intensifying screen, film, intensifying screen
Which term describes tissues/materials which absorb most of the x-ray beam?
Radiopaque
Which term describes tissues/materials which absorb little/none of the x-ray beam?
Radiolucent
What is the function of the lead foil in the x-ray film packet?
Absorbs scatter
Which item in an extra-oral film cassette ensures the x-ray exposure of the patient is kept to a minimum?
Intensifying screens (fluoresce when exposed to radiation)
Why are film holders used when taking bitewings and periapicals?
Allows horizontal and vertical alignment of the collimator
Why is the lid on the developer closed after use?
To prevent oxidation
Is the developer alkaline or acidic?
Alkaline
Is the fixer alkaline or acidic?
Acidic
Which light-sensitive chemical is used to coat the celluloid film in an intra-oral film packet?
Silver bromide salts
Do you need to check the temperature of chemicals in an automatic processor?
No, the machine regulates it automatically
What is the most likely cause of a film being lost in an automatic processor?
Dirty rollers
Which light-sensitive chemicals are used to coat the celluloid film in an extra-oral film cassette?
Rare earth chemicals
What is the term used to describe the process followed when an x-ray machine malfunctions?
Contingency plan
What is the aim of radiography quality assurance programmes?
Minimise patient exposure to an acceptable level