Radiation & Energy Flashcards
What is radiation?
Describe X-rays (4)
Energy
High energy
Short wave length
Can penetrate matter
Potential to cause damage to human cells
Describe ALARP Principle
As Low As Reasonably Practicable
Get radiation dose & position of body right first time
Describe Kilovoltage Peak
(kVp) (3)
Energy of the beam
Larger energy for larger body parts
Affects contrast on the image
Describe milliampereseconds
(mAs) (4)
Amount of x-ray photons
Current flowing from the cathode to the anode
Duration of the exposure
Affects density of the image
Describe contrast
The diff bw components in an image
kVp
Describe density
The amount of X-rays, overall darkness of image
mAs
Describe interactions of x-rays with the patient
1.Pass through the patient
•Amount and intensity is converted
to the x-ray image
2.Absorbed by the patient
•Do provide useful information
•White on x-rays
•May contribute to radiation damage
3.Scattered
•Contributes to noise
What is attenuation?
High & low
•Energy being lost due to the interactions in its path
•High attenuation
•metal and bones
•Low attenuation
•air and lungs
What is SID
•Also known as the Film Focus Distance (FFD)
•The distance from the x-ray tube to the imaging detector
•100/110cm for most skeletal imaging
•180cm for CXR
•Body part to be next to the detector
•Magnification and unsharpness
What is SOD
Small SOD creates an unsharp image
•Body part next to the detector
•Magnification
•Unsharpness
Describe grids & Bucky mechanism
Used for larger body areas
•Placed between the patient and detector
•Reduce scatter
•Improves image quality
•Uses a higher dose of radiation
•Grids are stationary
•The bucky moves/ossolates inside the
table or upright stand
Describe AEC
Automatic Exposure Chambers (AEC)
•Located between the patient and detector
•Will work out what the exposure factors should be at a given kVp
•Radiation cuts off once the detector has received a given density
Describe LBD
Light Beam Diaphragm (LBD)
•Where the middle of the x-ray beam is aimed/centered
•Cross light
Describe collimation
•The size of the field you are irradiating
•Limit to the area of interest
•Reduce dose to patient
•Improve image quality
•Reduce scatter
Use of anatomical side markers
•Lead or Pb markers
•Indicate the left or right side of the patient
•Important as images can be flipped
