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Radioactivity

Tracers.

Radioactive tracers can be used in medicine and industry.

A radioisotope can be injected into blood to detect internal bleeding.
Internal bleeding can occur inside the body
when blood is lost from a damaged vein
although it may not be obvious where the bleeding is happening.
The method used to detect the bleeding is the same as that used in industry
 to find a leak from an underground pipe.

Radioactive iodine-131 can be used
to see if the thyroid gland in the neck is working properly.
Iodine is present in small amounts in the body
and up to ¼ of the total amount can be stored in the thyroid gland.
The amount of iodine entering the gland can be seen
by detecting the radioactivity emitted from the radioactive iodine.

A radioisotope which is used inside the body must be
a b emitter or g emitter with a short half-life,
which will minimize the harm done to the cells of the body.
Iodine-131 is a b emitter with a half-life of 8 days.
An a emitter cannot be used
because the a-particles cannot penetrate the body tissue.

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