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Principles of disease (Ross Lilley) > Introduction to imaging > Flashcards

Flashcards in Introduction to imaging Deck (12)
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1

x-ray

an electromagnetic packet of energy with a extremely short wavelength between 0.1 and 10 nanometres

2

principles of x-ray production and capture.

1. the anode (tungsten filament) is heated and undergoes thermionic emission, discharging electrons
2. electrons attracted to positively charged cathode.
3. they hit the tungsten and cause the emission of x-rays.

3

why different structures have different appearances in x-ray imaging

this due to different attenuation coefficients ( the ability of a substance to stop radiation).

4

attenuation coefficient

the ability of a substance to absorb and scatter radiation.

5

CT scan

computed tomography.
Rotating x-ray tube that produces multiple beams on a single axis of rotation.

6

pros and cons of CT scans

pros:
-great for defining bony detail
-soft tissue more visible than in normal x-ray imaging.
cons:
- exposure to radiation
-more expensive

7

Ultrasound

ultrasound machine transmits high-frequency sound pulse which are reflected back and picked up at a boundary between tissues.

8

Ultrasound pros and cons

Pros:
-cheap
-portable
-no radiation
-great for soft tissues
cons:
operator dependent

9

Barium study

patient ingests barium solution or it is inserted into them. X-rays are then used to produce a sort of "X-ray film".

10

Barium study pros and cons

pros: real-time images that are live.
cons: bowel disturbance, colonic perforation at enema

11

iodinated contrast media

used to clearly show anatomical structures on x-rays. The elements in them have a high atomic number and so absorb more x-rays than the surrounding tissue.

12

ionising radiation harm

damages DNA of cells which can either be repaired or cause cell death and transformation. Cells in rapidly dividing tissues are particularly susceptible to damaging effects.