50 Q Flashcards
In an intra-oral X-ray set, X-ray photons are produced at the…
- aluminium filter
- cathode
- filament
- focussing cup
- tungsten target
- tungsten target
In an intra-oral X-ray set, what is the purpose of the aluminium filter?
- Absorb scattered radiation
- Help create a sharper image
- Preferentially attenuate low energy X-rays
- Prevent backscatter from fogging the image
5 . Protect the operator
- Preferentially attenuate low energy X-rays
In an intra-oral X-ray set, what is the purpose of the collimator?
- Absorb scattered radiation
- Focus the X-rays
- Protect the operator from scatter
- Remove the lower energy radiation from the beam
- Restrict X-ray beam to chosen area
- 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
- is usually about 6.5 - 7.5 mA
- is usually around 65,000 kV
- operates at around 50,000 Volts
- varies according to the exposure setting
- is in the 65-70 kVp range
Compton (inelastic) scatter…
- improves image quality
- occurs at discrete energy levels
- occurs when an electron interacts with an atomic nucleus
- produces an X-ray of energy equal to the binding energy of the k-shell
- reduces contrast in an image
- reduces contrast in an image
The mA current setting on an intra-oral X-ray set…
- controls the high tension (HT) circuit for the set
- controls the number of electrons produced at the filament
- is set higher for a bite-wing than for a periapical radiograph of an upper
molar - is the Mega Amp current
- is usually set for each exposure by means of the control box
- controls the number of electrons produced at the filament
In an intra-oral X-ray set, excess heat is …
- caused because X-ray
- production is inefficient
- conducted away by the copper block
- dissipated by convection in the oil surrounding the tube
radiated away from the outer case - All of the above
- All of the above
Rectangular collimation…
- ensures object and receptor are in the correct relationship
- helps align the tube to the film
- holds the film in the correct position
- is mandatory
- reduces the patient - dose by around 40%
- reduces the patient - dose by around 40%
The stochastic effects of ionising radiation…
- can result in radiation-induced erythema or burns
- cause no biological damage at low doses
- follow a linear-quadratic relationship
- have a safe threshold
- occur as the result of chance events
- occur as the result of chance events
. Which statement is true with regards to the paralleling intraoral technique?
- It enables the beam to be centred to the film
- It increases magnification of the image
- It is not appropriate for patients with disabilities
- It is not the technique of choice routinely
- Periodontal bone levels are poorly represented
- It enables the beam to be centred to the film
Collimation of the X-ray beam…
- is not necessary
- increases scattered radiation
- increases the volume of exposed tissue
- should be circular
- should be rectangular
- should be rectangular
The deterministic or non-stochastic effects of ionising radiation…
- are concerned with the risks of inducing cancer at low doses
- are dose-dependent
- are independent of the amount of radiation received
- have no threshold
- occur according to the laws of chance
- are dose-dependent
The X-ray beam should be…
- as close to the patient as possible
- kept on for as long as possible
- perpendicular to the tooth and image receptor to prevent distortion
- positioned perpendicular to the floor
- produced from a large focal spot
- perpendicular to the tooth and image receptor to prevent distortion
The risk of developing cancer from low doses of ionising radiation…
- clearly demonstrates a hormesis effect
- follows the linear-no-threshold model
- has a ‘dose threshold’
- is independent of the dose received
- is non-existent at very low doses
- follows the linear-no-threshold model
The Frankfort baseline is…
- a radiographic plane that bisects the first upper molar
- a radiographic plane that divides the face symmetrically from the crown
of the head to the tip of the mandible - a radiographic plane that extends from the external auditory meatus to
the infra-orbital margin - a radiographic term that describes normal anatomical appearances
viewed on an DPT - the relative position of the tube, cassette and patient during DPT
examinations
- 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
- Committed dose
- Dose-width product
- Effective dose
- Equivalent dose
- Absorbed dose
An X-ray of a female patient of child-bearing age…
- can only be undertaken if she is given a lead apron to wear over her abdomen
- can only be undertaken within 10 days of the last menstrual period
- is prohibited under the Ionising Radiations(Medical Exposure ) Regulations unless a check is made if she is pregnant
- must be undertaken in accordance with local written procedures
- must not be undertaken if she is pregnant
- 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
- image quality is high
- patient dose is less than the Diagnostic Reference Level
- patient dose is low
- patient receives a dose at the diagnostic reference leve
- dose is as low as achievable and image quality is acceptable
Under IRMER…
- operators do not require theoretical training
- students under supervision must be trained before carrying out exposures
- the Operator must have practical training
- the Practitioner does not require theoretical training
- the Referrer must be appropriately trained
- the Operator must have practical training
Regarding Justification…
- Does not apply to asymptomatic exposures
- Examinations on children under 5 are not justified
- Examinations on pregnant patients are not justified
- Justification is not required for routine x-rays
- Justification must be carried out for every exposure
- Justification must be carried out for every exposure