2024-2025 Flashcards
In an intra oral X-ray photons are produced at the
Tungsten target
In an intra oral X-ray set what is the purpose of the aluminium filler
Preferentially attenuate low energy x rays
In an intra oral X-ray set what is the purpose of the collimator
Restrict X-ray beam to chosen area
In an intra oral X-ray set the high tension (voltage) circuit
Is in the 65-70 kVp range
Compton (inelastic) scatter
Reduces contrast in an image
The mA current setting on an intra oral X-ray set
Controls the number of electrons produced at the filament
In an intra oral X-ray set excess heat is
All of the above
Rectangular collimation
Reduces the patient - dose by around 40%
The stochastic effects of ionising radiation
Occur as the result of chance events
Which statement is true with regards to the paralleling intra oral technique
It enables the beam to be centred to the film
Collimation of the X-ray beam
Should be rectangular
The deterministic or non stochastic effects of ionising radiation
Are dose dependent
The X-ray beam should be
Perpendicular to the tooth and image receptor to prevent distortion
The risk of developing cancer from low doses of ionising radiation
Follows the linear no threshold model
The Frankfort baseline is
A radiographic plane that extends from the external auditory meatus to the infra orbital margin
The national diagnostic reference dose for intra oral radiology is approximately 2.0mGy
What is this is expressed in terms of
Absorbed dose
An X-ray of a female patient of child bearing age
Must be undertaken in accordance with local written procedures
Under IRMER optimisation ensure that the
Dose is as low as achievable and image quality is acceptable
Under IRMER
The operator must have practical training
Regarding justification
Justification must be carried out for every exposure
Regarding justification the
Practitioner is responsible for justifying the exposure
The ionising radiation (medical exposure) regulations 2017
Are intended to protect patients
What do the ionising radiations regulations 2017 require
All exposures to be restricted as far as reasonably practicable
Members of staff should
Inform her employer in writing if they believe they are pregnant
Concerning controlled areas
Are subject to written arrangements to control access
The radiation protection supervisor (RPS)
Must have received appropriate training
The role of the radiation protection supervisor is to
Ensure that local rules are being followed and enforced
The absorbed dose at the cone for a mandibular molar radiograph is approximately
2 mGy
Bremsstrahlung or ‘braking radiation’ is
The major source of photons in X-ray tube
The useful interaction of photons with matter when taking intra oral X-rays is
Photo electric absorption
What is a diagnostic reference level (DRL)
Is the radiation dose which should not be normally exceeded for a standard exposure
Beam collimators should provide a minimum focus to skin distance (FSD) of
200mm
Intra oral radiography equipment should operate within which tube potential range
60 - 70 kV
X-ray production in a diagnostic X-ray tube is approximately how efficient
1%
How far away from the dental X-ray tube does the controlled area extend
As defined in the local rules
Regarding the photoelectric effect
The incident photon is completely absorbed
Regarding effective dose, it
Expresses the probability of cancer incidence in a population
Regarding absorbed dose
Absorbed dose is a measure of the energy deposited in tissue per unit mass
Regarding the Bremsstrahlung (braking radiation) process
An incident electron interacts with the nucleus releasing an X-ray photon
Image unsharpness is not affected by
Increase in kVp
Patient dose is not affected by
Using a rotating anode target
Dose optimisation is the process by which
A diagnostically relevant image is obtained at the lowest dose
The minimum legal filtration for a dental X-ray set (up to 70kVp) is
1.5mm Al
Deterministic effects of ionising radiation
Have a threshold dose below which they do not occur
Stochastic radiation effects
Are assumed to follow a linear no threshold relationship to dose
Compton or inelastic scattering
Is the most likely source of radiation exposure to an operator
The X-ray beam should be collimated to
Limit extraneous radiation that does not play a part in the imagining process
Equivalent dose is the
Absorbed dose to an organ or tissue weighted for type of radiation
The health and safety executive
All of the above
Which of the following is not required in the local rules
An exposure chart containing both local and national diagnostic reference levels
