Uses of Nuclear Radiation
Nuclear radiation is
used in two ways in medicine:
- as
a tracer
(also see PET scans) - Radioactive
isotopes and radioactively labeled molecules are used
as tracers to identify abnormal bodily processes.
This
is possible because some natural elements tend to concentrate
in certain parts of the body: iodine in the thyroid, phosphorus
in the bones, potassium in the muscles.
When a patient
is injected with a radioactive element, a special camera
can take pictures of the internal workings of the organ.
- as
therapy - for example a medical treatment for cancer (radiotherapy). A high radiation dose causes cell death.
| |
Radioactive
Tracer
|
Radioactive
Treatment
|
| Type
of treatment |
Diagnostic |
Therapy |
| Aim
of treatment |
To
investigate the function of a part of the body by labelling
a biologically useful compound with radioactive atoms |
To
destroy malignant tumours with a high dose of radiation that will
result in cell
death |
| Type
of dose administered |
Minimal
dose
to patient |
Maximum
dose
to affected part, minimum dose to surrounding tissue |
| Type
of radiation used |
Gamma
Rays |
Gamma
Rays |
| Example
of substances used |
Pure
gamma emitters such as technetium
99m |
Pure
gamma emitters such as cobalt
60 and caesium 137 |
| Half
life |
Short
( about 6 hours) |
Long
(typically 5.3 years) |
| Treatment |
Radioactive
substance is injected into the patient making him/her mildly radioactive.
The nuclear radiation emitted is then 'viewed' using a gamma
camera |
A
strong radioactive source is used to deliver nuclear
radiation to the affected part. If this is from outside the
body the patient doesn't become radioactive BUT if it is from an
implanted source (like a radioactive wire inserted into the tumour)
the patient does become radioactive and usually has to stay in hospital
until the source is removed. |
| What
equipment is used? |
The
'hardware' in the hospital (a gamma
camera) does not deliver radiation but detects it. |
The
hardware in the hospital (a LINAC
- linear accelerator or Cobalt 60 unit) produces ionising
radiation which is 'fired' at the patient. |
| How
does the patient feel afterwards? |
After
the investigation the patient does not feel unwell |
After
the treatment the patient may well feel unwell: sickness, nausea,
exhaustion. |
| Is
the patient radioactive
afterwards? |
After
the investigation the patient is still mildly radioactive
and may need to avoid contact with pregnant women and young children
for a couple of days to minimise any risk to them. He/she will be
told not to use public transport or to go to public places to avoid
inadvertent contact with such individuals. |
After
the treatment the patient is NOT radioactive.
He/she may see other people straight away (although feeling unwell
may not wish to). |
LOJ
(February 2001)
- revised February 2003
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