Imaging techniques

Question 1

List common imaging techniques

Answer 1

X-Ray
MRI
Ultrasound
CT scan 
PET (positron emission tomography)

Question 2

What can X-ray be used for and what are its limitations?

Answer 2

Can be used to assess bone injuries (bone shows up very well), check for fluid in lungs, joint space, organ checks, surgical procedure to guide instruments.

Involves radiation, cannot be used on pregnant women, cannot create a 3D image, not as clear as MRI/CT

Question 3

Describe the use of ultrasound scan and its pros and cons

Answer 3

Sends high frequency sound pulses from a probe and pluses echo back from tissues and are recorded and displayed as images.

Pros: NO radiation, very quick, cheap, good for looking at organs, soft tissues, muscles.

Con: Does not penetrate bone so can only see cortex, depends on physique (won’t work on obese people). Not very detailed images.

Question 4

Describe what a Computerise Tomography is used for and its pros and cons

Answer 4

Ultrasound uses X-rays at different angles to gain a 3D image.

Pros: shows real time, detailed images, shows bones very well (better than X-Rays), good for assessing organs.

Cons: much higher dose of radiation than X-rays

Question 5

Describe how an MRI works

Answer 5

Powerful magnets are used to create a strong magnetic field.

Radiofrequency current is pulsed though the patient which disrupts and misaligns the protons in the body. When the radio frequency current is switched off, radio frequency receivers detect the energy release as the protons return to resting state (realign with magnetic field).

This radio frequency signal is sent back to the computer where an image is produced

Question 6

List the pros and cons of MRI

Answer 6

Pros: very good at looking at bone, soft tissues, organs, muscles. esp. brain, NO radiation.

Cons: claustrophobic, must remove all metallic items due to the strength of the magnet, expensive, quite noisy. cannot be used on pregnant women.

Question 7

describe the PET scan, give an example of when it may be used.

Answer 7

Positron Emission Tomography: A radioactive tracer (fludeoxyglucose) is injected into arm or swallowed and the radiation given off is detected. It highlights areas that are metabolically active as it shows glucose uptake.

Used in detection of cancer metastasis as the glucose is taken up faster than other cells.

Question 8

what type of radiation is used in Nuclear Medicine ?

Answer 8

Gamma rays