radiography Flashcards
The collective term for best describing the black, white and grey shadowing on a developed xray are better known as…..
Contrast
What type of radiation is used in dentistry?
Ionising Radiation
When we talk about Z in Radiation, what do we mean ?
The number of Protons (+) In the nucleus of an atom
The nucleus is made up of what?
Neutrons (no charge) and protons (+)
What is the process known as removing an electron (-) from an atom?
Ionisation
The closest shell to the nucleus is known as the what?
K Shell
What does the focusing device do in the x-ray tube?
It aims the stream of electrons (-) at the focal spot of the target
When does heat producing collisions take place?
When an incoming electron collides with an outer shell
Continuous spectrum happens when?
the xray electron passes close to the nucleus of the atom
What is attenuation in relation to xrays striking matter?
Absorption and scatter
When electrons (-) bombard the target, What percentage of xrays produced?
1%
What is the radiation absorbed dose?
The measure of the amount of energy absorbed from the radiation beam per unit mass of tissue
What is the background radiation estimated at approximately?
2.7 mSv
Deterministic effects will happen if….?
….the body is exposed to a high dose of radiation
The photoelectric effect is described as…?
Pure absorption with low energy photons
A step down transformer is used for what….?
Changes the incoming mains voltage from 240v to a low voltage current required to heat the filament
What is indirect action to cells within the body?
Involves the breakdown of water molecules
Fatal radiation induced malignancy from a BW xray in adults- What is the risk?
1 in 20000000
What is a spacer cone also known as?
beam indicating device
What is a direct action radiographic film?
is sensitive primarily to xray photons
What does the lead foil do in a xray film packet?
prevents scattered radiation
Calcium tungstate screeens are sensitive to what coloured light?
Blue
In chemical processing the silver halide crystals are converted to what colour metallic silver in the development stage?
Black
In this instance in chemical processing the temperature of the developer is 20 oC, how long should the film be immersed for?
5 minutes
The Ionising Radiations Regulations 2017……
Came into force on 1st January 2018
The Ionising Radiation (medical exposure) Regulations 2018 states that….
the practitioner must justify an exposure
Non classified workers in relation to radiation, their dose per year should not exceed
6mSv a year
Radiolucency on a radiography will show as….?
completely Black
What is and advantage of using the bisecting angle technique?
is quick and simple to use
When taking a BW xray the tubehead should be positioned….?
5-8o downwards
What is and advantage of using BW holder?
the image receptor is held firmly in position and cannot be displaced by the tongue
What is an upper standard occlusal radiograph used to?
detecting unerupted canines or supernumeries
cephalometric radiographs…..
Can be used in orthognathic surgery planning
In dental panoramic tomography…..
The focal trough is horseshoe shaped
When positioning a patient for DPT the patient should….
Keep their spine straight
A main advantage of using DPT is….
compared to full mouth survey using intraoral films it is about 1/5 the radiation dose
A too dark image is caused by…..
being overdeveloped
Images that are unsharp/blurred could be caused by?
film packet being excessively bent
Where do you find cervical burn out?
at the neck of the tooth. (not to be mixed up with root caries)
What is the correct colour of mop and bucket to clean a surgery floor?
yellow
How many hours of eCPD do you need to complete in a 5 year cycle?
50
How many principles are there in the GDC standards? 5,6,7,8,9
9
What has a target?
Anode
A photon charge is…?
nil
What is Z?
the atomic number
What is removed from an inner to an outer shell to cause excitation?
electron
braking radiation is also known as…?
continuous spectrum
electrons jumping from one energy shell to another and emits xray photons is called..?
characteristic spectrum
energy below 69.5 kV is known as what?
characteristic k line
Which is the fastest intensifying screen?
rare earth
Which states xray equipment having to have a light, audible warning when exposing xray?
Ionising radiation regulations
Who is responsible for overall safety of staff when using radiation?
radiation protection supervisor
Which clarifies the positions of responsibility regarding employer, referrer and operator?
Ionising radiation (medical exposure) regulations
what should be kept by all xray machines?
local rules
what should be used by all staff taking more than 100 intraoral or 50 extraoral xrays a year?
personal monitoring
All patients should be treatment using….?
safety glasses/spectacles
What should not be used when opening film packets?
powdered gloves
how should pts be seated when taking bws?
occlusal plan horizontal
when xraying pt what should you think about before hand…..?
pt dose constraints and radiographic audit
under which heading checks the performance of the counterbalance for the correct position of the tube head
equipment checks
the coin test comes under which heading/checks?
darkroom inspection
what is directly associated with step-wedge test?
image processing
inverse square law is best related to what?
increasing the distance between the radiation source and the personnel
Your employer gives training on new receptor holders, , what are you most likely to consider when using these?
avoiding unnecessary radiography
A 16 year old boy comes to do work experience at the practice, you ask work colleague to look after him whilst xrays are being taken. What should be considered?
reducing exposure factors
Changing from D speed to E speed, what should be considered?
reduce exposure factors
