Applications of Nuclear Technology
There are many applications of nuclear technology. These are discussed
in separate topics as follows:
The following will be separated later in other webpages.
Neutron Activation Analysis
Neutron Activation Analysis
The practice of nuclear medicine involves injecting a liquid radioactive
pharmaceutical (radiopharmaceutical) into a patient. Signals from the
radiopharmaceutical are then detected and processed into a useful image
by sophisticated instruments in order to diagnose or treat a disease
state. A radiopharmaceutical is formed by combining radioactive atoms
radioisotopes) with chemical or biological material formulated to collect
temporarily in the part of the body to be imaged...
A nuclear pharmaceutical is a physiologically active carrier to which
a radioisotope is attached. It is possible to manufacture chemical or
biological carriers which migrate to a particular part of the human body.
Calcium, for example, is a bone 'seeker', and iodine concentrates in the
thyroid gland. The radioisotope attached to these compounds emits
radiation so that the relevant organ and its functioning can be
'observed'. Radiation is easy to detect. Even radiation which is many
times weaker than natural background radiation can be measured.
The location in the patient's body which emits the radiation can
thus be very accurately pinpointed.
So we see that radioactive preparations can be very useful for
diagnostic examination if we choose them in such a way that they
emit sufficient radiation to be easily detectable in the body,
but only for a long enough time to enable completion of the examination.
Nuclear pharmaceuticals for diagnosis must therefore have a rather
short half-life, preferably no longer than a few hours. Useful
radioisotopes for diagnostic purposes are technetium-99, gallium-67,
indium-111, iodine-123, iodine-131, thallium-201, krypton-81m.
Tissue dies rather quickly after receiving a large dose of radiation.
This aspect of radiation can be utilized for treating tumours.
The goal of therapy in nuclear medicine is to use radiation to destroy
diseased or cancerous tissue while sparing adjacent healthy tissue.
For certain types of cancer, this is achieved by using an external
radioactive beam directed at the cancerous tumor. It is also possible
to insert a small radioactive source through body openings, via the
bloodstream or by means of surgery into a tumour and leave it there
for a period lasting from days to weeks until sufficient dose has
been given off. With the exception of radioactive iodine, which is
used to treat cancer of the thyroid (see picture), few radioactive
therapeutic agents are injected or swallowed. A much higher dose of
radioactivity is administered in a therapeutic situation than in a
diagnostic one; thus the therapeutic radiopharmaceutical must have a
high affinity for the diseased tissue relative to the healthy tissue.
Nuclear pharmaceuticals which are used for therapy must have a rather
Useful radioisotopes for therapeutical purposes are iodine-131
(in NaI or in metaiodobenzylguanidine, MIBG), phosphorus-32,
iridium-192, gold-198. Radioactive sources which are placed in the
body near the tumour for local irradiation of the tumour are also
called nuclear pharmaceuticals. Iridium-192 sources are normally
used for this purpose.