X-Rays Nuclear Medicine Medical Ultrasound Magnetic Resonance Imaging.

X-Rays Nuclear Medicine Medical Ultrasound Magnetic Resonance Imaging

Discovered in 1895 by Roentgen

An ionising radiation at a higher level on EM spectrum

Higher frequency or shorter wavelength

Non-Invasive Well established

technology Still evolving Flexible Readily available

and therefore relatively cheap

Ionising Radiation Not good at

imaging soft tissue on its own

Use of unsealed radioisotopes Attached to pharmaceuticals Drugs absorbed preferentially by target

organ(s) Gamma emitter so can be detected Images digitally produced from data

gathered

Can image wide variety of tissue types

Easy to target specific tissue

Can image function Utilises by-products

of other processes so cost effective

Uses ionising radiation

Could be described as invasive

Has many radiation protection issues associated with it

Better applications are expensive

Manipulation of natural magnetic field Magnetic resonance is detectable and

measurable Data detected can be digitally converted

to an image Utilises tomographic techniques of CT

Atoms have magnetic moments They spin in a magnetic field – Precession Spin frequency depends on the type of

atom or molecule – Larmor Frequency Examine the spin of hydrogen atoms Hydrogen atoms in different tissues have

different Larmor Frequencies

Does not use ionising radiation

Excellent at demonstrating soft tissue

Non Invasive

Good at cancer diagnosis

Non-Invasive Does not use

ionising radiation Excellent for soft

tissue imaging Can image function

Very Expensive Has its own health

and safety issues Has “acceptability”

issues with some patients

Utilises sound waves at ultrasonic frequency

Above 20KHz is ultrasound but usually 3 - 10 MHz for medical imaging purposes

Echoes from tissue can be detected and data interpreted digitally to produce image

Position and depth of the echoes builds up a complete picture

Non-Invasive No ionising

radiation Dynamic technique Can image soft

tissue effectively Flexible equipment Relatively cheap

Limited in what can be imaged

VERY user dependant

What information do we require? Do we wish to see function or structure? What can the patient tolerate? What would the clinician prefer? What is available for use? Is there a safer/cheaper alternative? Can potential risks be justified?