Radiation and Protection Flashcards
What are the 3p’s?
Presence, pathology, position
What are the two types of parallax?
- horizontal
* vertical
4 types of radiographs used in orthodontics?
DPT
lateral ceph
Upper standard occlusal
Periapicals
What must be taken prior to taking a radiograph?
- up to date medical history
- clinical examination
- date patient last had a radiograph
- consent
What does ALARP stand for?
As Low As Reasonably Practical
5 ways to reduce the risk of radiation to patients?
Justification for radiographs Optimisation - only take when needed Quality assurance programme Training of operators Maintain equipment
5 ways to reduce risks of radiation can be reduced to staff?
Controlled zone Personal dosimeter Risk assessment Training Local rules
What does IRR stand for and who does it protect?
Ionising radiation regulations
Protects workers and general public
What does IRMER stand for and who does it protect?
Ionising radiation medical exposure regulations
Protects patients
What X-rays are used in horizontal parallax?
Two periapicals or periapicals and USO
What X-rays can be used for vertical parallax?
OPG and upper standard occlusal
What does DPT stand for?
Dental Panoramic Tomograph
What is parallax?
The relative movement of an object when using 2 images taken from different positions (need a minimum of 20 degree tube shift)
What does SLOB stand for?
Same
Lingual
Opposite
Buccal
What percentage of radiographs should be graded diagnostically acceptable?
No less than 95%
What percentage of radiographs should be graded not diagnostically acceptable?
No more than 5%
What percentage of radiographs should be Grade 1?
70% or more
What percentage of radiographs should be Grade 2?
Less than 20%
What percentage of radiographs should be Grade 3?
Less than 10%
Who must be notified of the routine use of dental X-ray equipment in the dental practice or any modifications/repositioning of X-ray equipment?
The health and safety executive
What is an RPA?
Radiation protection advisor
An individual that provides advise to employers on compliance with IRR
What does an RPA advise on?
All aspects of radiation protection: • controlled areas • installing equipment • modification and testing equipment • risk assessment and contingency plans • staff training • dose assessment • quality assurance programme
What does RPS stand for?
Radiation protection supervisor
Who is responsible for implementing local rules?
The employer
What information should be included in the local rules?
- name of RPA and RPS
- identification and description of the controlled area and summary of arrangements that restrict access
- summary of working instructions
- summary of contingency plans in the event of an accident
- dose investigation level
- name of legally responsible person for use for equipment
- name and contact details of RPA
- arrangements of personal dosimetry
- arrangements for pregnant staff
- reminder to employees of legal responsibility’s under IRR
What are the positions of responsibility with IRMER?
- the employer
- the referrer
- the practitioner
- the operator
Define justification
The benefit to the patient from the diagnostic information obtained should outweigh the risk of exposure
Who is responsible for justifying X-ray exposures?
The IRMER practitioner
If an X-ray is deemed grade 3/non diagnostic, should the operator repeat the exposure?
- yes
- if the X-ray is not repeated or an alternate exam is performed, then it would suggest the exposure was not justified in the first place
- the operator should assess why the X-ray was non diagnostic and aim to repeat ensuring reasons behind poor quality image are resolved
What is meant by dose optimisation?
All doses should be kept as low as reasonably practical
Is an RPS mandatory?
Yes. They are usually a dentist, hygienist or senior dental nurse - as long as they have relevant qualifications and training
Does a practice using ionising radiation require an RPA?
Yes - it is mandatory. An RPA
must be appointed in writing and consulted to give advice on IRR
Can a dental nurse with a radiography certificate be an RPA?
No - an RPA is an expert on radiation protection, usually a medical physics expert
What is the controlled area?
- a defined space where entry, activities and exit are controlled
- warning lights or signs should be displayed
- only patients should be in designated space during exposure
What protection measures are in place to protect the general public from ionising radiation?
- appropriate siting of X-ray equipment
- appropriate thickness and materials of walls and windows
- safe design of controlled area
- correct position of audible and visual warning signs
What are deterministic effects?
The damaging effects to the body that will definitely result from a large dose of radiation
What are stochastic effects?
A random chance effect, it is said there is no threshold dose. Any exposure to radiation carries a chance of stochastic effects
As a practicing operator who regularly takes X-rays, is continued education required?
Yes - an operator should attend an update course at least every 5 years
What is covered in 5 yearly IRMER training?
- principles of radiation physics
- risks of ionising radiation
- radiation dose and factors affecting radiation dose
- principles of radiation protection
- statutory requirements
- quality assurance
Describe the slob rule
SLOB = same lingual opposite buccal
If the tooth is palatally positioned it will appear to have moved in the same direction as the tube head
If the tooth is buccally positioned it will appear to move in the opposite direction of the tube head
If an unerupted canines lies Within the dental arch which way will the tooth move with respect to the tube head when applying parallax?
The tooth will appear to have not moved
How can radiation doses be reduced?
- ALARP
- justification
- collimation of beam
- filtration of beam
- rare earth intensifying screens
- regulation of voltage
- fast films
- short exposure times
- warning signals
- quality control
What pathology can be seen in a DPT?
Caries
Root resorption
Periodontal problems
Cyst formation
