Principles of Radiography Flashcards
Xrays are part of what spectrum
Electromagnetic spectrum
Electromagnetic radiation is grouped into categories according to ______ & ______
wavelength and frequency
Define:wavelength
Wavelength is ___________
the distance between two identical points
define: frequency
Frequency is _____________
the number of wavecycles in a second (H2)
If wavelength is increased the frequency will ___________
DECREASED
Shorter wavelengths = ____________ frequency = ____________ energy
Shorter wavelengths = HIGHER frequency = MORE energy
Longer wavelengths = ____________ frequency = ____________ energy
Longer wavelengths = DECREASED frequency = LOWER energy
Three properties of all electromagnetic waves
All magentic waves:
- Travel in straight lines
- Travel at the same speed
- Can travel through a vacuum
Useful properties of xrays 1 2 3 4 5
- Penetrate certain substances
- Produce a photographic image
- Can cause some substances to flouress
- Energy can be converted into a digital image
- Can cause damage to atoms in living cells
Define: Hard Xrays
Short wavelengths - High energy
Define: Soft Xrays
Long wavelengths - Low energy (contibutes to scatter)
X-Ray equipment
– Focal spot –
Focal spot is the small area on the target where the electrons colide
X-Ray equipment
– Focal spot –
Size
Size of the focal spot is a balance between
- Small as possible to achieve a sharp image
- Large as possible to avoid heat damage
X-Ray equipment
– Focal spot –
Angle
If the target spot is angled 20degrees then the actual focal spot can be much larger than the effective focal spot
X-Ray equipment
– Light beam –
Box placed under the tube head containing adjustable lead shutters to collimate the beam.
an inbuilt light soure shows exactly where the primary beam is
X-Ray equipment
– Tube stand –
System of support for the tube head
control pannel
- on off switch
only one when taking radiographs
control pannel
the line voltage compensator
to supply a consistent voltage
control pannel
the kilovolts selector
may be linked to the mA, may be fixed
control pannel
The millamperage control
May be linked to kV or may be fixed
control pannel
the timer
Sets the length of exposure (mAs) Milliamps per second
control pannel
the exposure button
two stage
1 - prep (tungsten releasing electrons)
2 - fully depressed (cathode becomes negative to release electrons)
control pannel
warning lights
-exposure light/beep
- overload light
- exposure light to notify when the exposure if being taken
- overload light - auto cut out if it gets too hot in the xray head
Portable x-ray machine
- low output, longer exposure.
- used in equine or farm radiography
Mobile machines
- bigger and more powerful
Fixed machines
most powerful xray machines, used in small animal
Three ways that xrays interact with matter
absorbed - white film
pass through unchanged - black film
pass through to a degree - grey film
Define: Radiolucent
Does not absorb x-rays
Examples of radiolucent material
Air
Define: Radiopaque
Xrays all absorbed - none pass through
Example of radiopaque material
Bone
Define Radiographic (/film) density
the degree of blackening on the film
Define Radiopacity
the degree to which a substance impeeds the rays (absorbs)
define Radiolucency
the degree to which a substance allows the xray beam to pass through unimpeeded
