In both cases seeral things must be considered

Gamma ray sources must be used, because alpha and beta rays would be absorbed by (and damage) the body

Gamma ray sources do cause some ionisation, and so the patient will be exposed to some radioactivity, as may be the patient's family and nurses

The half life of the source must be long enough to carry out the investigation, but no longer

Time must be allowed for the source to be brought from its manufacturing site to the hospital

The source must not be chemically poisonous

It must be possible to get the radioactive material to the part of the body where it is needed

Once the tracer is in the body it must be possible to monitor it

Advantages and disadvantages to MRI

Oh yes, Snog, Marry, Avoid is back on!

There is no ionising radiation involved, so neither patient or staff receive any radiation dose

The quality of the image is high

There is a good distinction between different types of soft tissue

Bone provides no barrier to the radio waves, so pictures inside the brain, for example, are clear

There are no side effects from having a scan

No metallic objects can be scanned, or they heat up. Patients cannot be scanned if they have pacemakers or surgical pins in bones in place

The equipment must not have any radio waves from external sources within it. It can be screened to eliminate stray fields.

The machines are very expensive and cannot have a fast throughput of patients since they take a relatively long time for each scan

Is this everything I need to know about MRI?

I've had an MRI before.

Is this everything I need to know about MRI?

 

Perhaps?

But unfortunately not everything I needs to know

I has to know how it works

And how it compares to other scans

But that can be tomorrows job :)

*spams*