Applications of Nuclear Technology

There are many applications of nuclear technology. These are discussed in separate topics as follows:

X-ray imaging in Varian
The X-ray Century
Teaching radiology on the Internet
Radioactive dating is an application of radioactive decay kinetics to determine the age of certain things since they became inactive, dead or being isolated.
Apollo 15 Gamma-ray Spectrometer

The following will be separated later in other webpages.

Neutron Activation Analysis

Nuclear Medicine

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.

Therapeutics

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 longer half-life.

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.