X-Ray Physics Flashcards
(64 cards)
What are filaments made of?
Tungsten
What is the source of electrons in producing an x-ray?
Filament
The focusing cup is part of the cathode or the anode?
Cathode
What is the name of the positive electrode in the X-ray tube?
Anode
What does an increase in mAs lead to?
Greater radiograph density
What is the term for a structure that produces more blackening on the film?
Radiolucent
What is the minimum change in mAs required to see a minimum change in density on the film?
30%
High or Low kVp, what produces high contrast imaging?
Low kVp
Linear or inverse: mAs and density
Linear
Linear or Inverse: kVp and contrast
Inverse
Which will lead to decreased radiation absorbed by the patient, high or low kVp?
High
What is the 15% rule?
An increase in kVp by 15% will double the overall density on the film; a decrease by 15% will cut the density in half.
Increasing kVp by 15% and decreasing mAs by 50% will do what to your contrast?
Lower
Decreasing kVp by 15% and increasing mAs by 100% will do what to your contrast?
Increase
Which side of the X-ray tube is the intensity greater?
Cathode side
What happens when you increase FFD?
Image gets smaller and clearer
What is the inverse square law?
Intensity of radiation varies inversely with the square of the distance from the source
What results from using large crystals in your intensifying screens?
Higher contrast and shorter scale (less patient exposure) but less detail
What is penumbra?
Blurry halo parts of the image
What causes penumbra?
Having the tube too close to the film
Having the patient too far from the film
Making the focal spot too big
What is the best OFD for a detailed image?
Object as close to the film as possible
What is the purpose of a grid?
To improve quality of the radiograph by absorbing scatter radiation
What is the grid ratio?
The height of the lead strips to the distance between the strips
What is the standard grid ratio in a chiropractic office?
12:1
