Introduction to imaging

Question 1

x-ray

Answer 1

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

Question 2

principles of x-ray production and capture.

Answer 2

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.

Question 3

why different structures have different appearances in x-ray imaging

Answer 3

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

Question 4

attenuation coefficient

Answer 4

the ability of a substance to absorb and scatter radiation.

Question 5

CT scan

Answer 5

computed tomography.

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

Question 6

pros and cons of CT scans

Answer 6

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

Question 7

Ultrasound

Answer 7

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

Question 8

Ultrasound pros and cons

Answer 8

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

Question 9

Barium study

Answer 9

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

Question 10

Barium study pros and cons

Answer 10

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

Question 11

iodinated contrast media

Answer 11

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.

Question 12

ionising radiation harm

Answer 12

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.