Taking a radiograph Flashcards
Explain how density affects the radiograph taken?
Lower density i.e: air, allows x ray photons to pass through easily, making the image black
Higher density i.e: bone, absorbs most x ray photons making the image white
What should we consider in radiography when dealing with different breeds/weights?
The larger the patient, the more exposure needed. They will also produce more CS, refer to exposure charts
What is the SID?
Source image detector distance: distance between focal spot and image receptor. It varies between 70-100cm
What is the SID inverse square law?
The intensity of the radiation from a given source is inversely proportional to the square of the distance between the focus and the receptor
What is OID?
Object image detector distance: distance between the object and receptor. It should be kept to a minimum to improve quality.
What is the exposure kVp?
kvp = kilovoltage peak
It accelerates the electrons towards the target. Has an effect on the contrast of the image (inc kvp).
What are exposure mAs?
mA = Milliamperage which is the current applied to the filament of the xray tube.
s = amount of time the current is applied for
Controls the amount of x rays produced. Effects density of image.
Why use exposure charts?
It tells you the correct mAs, kVp and if grids should be used for the patient so a good radiograph is carried out.
What are general rules regarding exposure charts?
Double mAs for obese/heavy patients. Half mAs for immature cat/dog and on the thorax.
What is geometric distortion?
When subject is not parallel to the x ray beam - appear elongated or shortened
