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The radiation therapy is of two types, one is the external radiotherapy and the second one is the internal radiotherapy. In the external radiotherapy, the radiations are focused on the tumors from... |
The radiation therapy is of two types, one is the external radiotherapy and the second one is the internal radiotherapy. In the external radiotherapy, the radiations are focused on the tumors from outside the body. In case of the internal radiotherapy, radioactive substances for radiation therapy called ’seeds’ are used. They are placed in the body of the patient.
For the production of the radiations in the external radiotherapy, there is the use of the machines that produce radiations with the help of electricity. While on the other, hand, in the internal radiotherapy, there is a use of the substances, which emit radiations. These radioactive substances for radiation therapy are to be placed inside the body and next to the tumors. In this method, radioactive substances for radiation therapy are further divided into sealed and unsealed sources. The sealed type of therapy is termed as the Brachytherapy or endocurietherapy.
The radioactive substances for radiotherapy, which are used commonly, are the Cesium (137Cs), Cobalt (60Co), Iodine (131I), Phosphorus (32P), Gold (198Au), Iridium (192Ir), Yttrium (90Y), and Palladium (103).
These are the radioactive isotopes of non-radioactive substances. They are prepared with the help of the appropriate method as bombardment with atomic particles, etc. The selection of the substances for radiation therapy is done by refereeing to a number of factors as, the application, and characteristics of these substances. These include the amount of radiation that they will emit, the duration for which they will remain active, the type of radiation that they will emit, etc. Further, the radioactive substances for radiation therapy are classified as the ones with the high dose rates and those with the low dose rate.
In the enclosed type of internal radiotherapy, the radioactive substances are kept in a case or covering as the silver foil, etc. These cases are called as the ‘plaques’. They allow only some of the emitted radiation to pass out of them.
The radioactive substances used in the unsealed radiation therapy are the soluble radioactive isotopes. In this method, the substances that are used generally are assimilated in the body. Therefore, the substances are chosen considering this. The rest of these radioactive substances for radiation therapy are omitted out of the body.