Radiography Flashcards
What is the purpose of aluminium filter
Remove long wavelength xray photons
Intensity of Xray beam will decrease as the distance from the X-ray tube to the film is increased
Inverse square law
Purpose of collimator
Narrow the beam to a specific diameter
What is density
Degree of darkness or blackness on the film
Error for dark films
Over developing or overly warm temperature
X-ray and children
The exposure factors may be slightly reduced
What is definition
Detail and clarity of the outline of structures.
What is contrast
Difference between dark and light areas
Incorrect horizontal angulation causes…
Overlapping image of teeth
Labial mounting method.
Patients left is your right
Image or picture produced by X-rays
Radiograph
The making or radiographs by exposing and processing X-ray films
Radiography
The study of x-radiation
Radiology
The original term roentgen applied to the invisible ray he discovered
X-ray
Anything that occupies space and has mass
Matter
The ability to do work
Energy
Generated by the radiography process
Energy exchange
The formation of ion pairs
Ionisation
A small particle able to penetrate matter
X-ray photon
Process by which unstable atoms undergo decay in an effort to obtain nuclear stability
Radioactivity
Amount of current passing though wires of the circuit
mA
determines the available number of free electrons at cathode filaments
mA
Determines amount of X-rays that will be produced
mA
Measures the voltage across the X-ray tube
kVp
Determine the speed it electrons travelling towards the target on the anode
kVp
Determines penetrating ability of the X-rays produced
kVp
Determines the duration of exposure
Timer
Unit of measurement of the timer
Mili-seconds
Incorrect horizontal angulation causes
Overlapping
Incorrect ventricle angulation causes
Elongation
Diagnostic quality radiograph
Obtaining the highest quality radiograph while maintaining the lowest possible radiation exposure risk for the patient
Lead layer
Absorbs scatter radiation and reduces clarity of image
Purpose of film processing
Produce diagnostic quality radiographs that can support oha
Psp plate storage vs radiography film
Psp plate- stores info as a digital image
Radiography film- latent image that is transferred into a visible permanent image
Radiolucency
Appears darker on film eg soft tissue and air space
Structures that permit the passage of X-rays with little or nonresistance
Radiopacity
Appears light on the film eg dentine, enamel, bone
Dense structures that absorb if resist the passage of X-rays
Error- film fog
White light leaking into dark room
Error- light image
Underdevelopment of film. Under exposure
3 principles of radiation
Justification- must be of benefit to the patient
Optimisation- alara principles, keep exposure as low as reasonably achievable
Limitation- maximise permissible dose
Properties of X-rays
Travel at the speed of light Invisible No charge Travel in straight lines Interact with matter causing ionisation No mass or weight Penetrate opaque tissues & structures Absorb biological tissue Absorb radiographic film emulsion
X-ray interaction with matter
Beam of X-ray passes through mater
Energy transferred from X-ray to atoms of material through which it passes
X-ray is weakened and gradually disappears
Disappearance= absorption of X-rays
Method of absorption= ionisation
Possibilities of interaction of X-rays with matter
No interaction
Coherent scattering
Photoelectric effect
Compton effect
Deterministic effect (non-stochastic)
Severity of the change is dependent on the dose
Stochastic effect
Based on the probability of occurrence rather than the severity of the change.
Cancer all or nothing occurrence
Alara
As Low As Reasonably Possible
Qualities of an operator: communication
Explain what you are doing
Reassure about radiograph
Qualities of an operator: your education
Continue your education
Understand how X-rays work
Qualities of an operator: your judgment
Is it needed?
Which X-ray should you take
Your understanding of contrast
The visual difference between shades from black to white on a radiograph. An image with good contrast will contain black white and enough grey shades to differentiate between structures and their conditions
Your understanding of density
The overall darkening of a radiograph. X-rays that appear light is said to have less density. X-rays that appear dark is more dense
