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Date: 6-12-2020
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Date: 28-1-2019
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Date: 29-12-2016
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Radioactive isotopes have numerous medical applications—diagnosing and treating illness and diseases. One example of a diagnostic application is using radioactive iodine-131 to test for thyroid activity (Figure 1.1 “Medical Diagnostics”). The thyroid gland in the neck is one of the few places in the body with a significant concentration of iodine. To evaluate thyroid activity, a measured dose of 131I is administered to a patient, and the next day a scanner is used to measure the amount of radioactivity in the thyroid gland. The amount of radioactive iodine that collects there is directly related to the activity of the thyroid, allowing trained physicians to diagnose both hyperthyroidism and hypothyroidism. Iodine-131 has a half-life of only 8 d, so the potential for damage due to exposure is minimal. Technetium-99 can also be used to test thyroid function. Bones, the heart, the brain, the liver, the lungs, and many other organs can be imaged in similar ways by using the appropriate radioactive isotope.
Figure 1.1 Medical Diagnostics
Radioactive iodine can be used to image the thyroid gland for diagnostic purposes.
Very little radioactive material is needed in these diagnostic techniques because the radiation emitted is so easy to detect. However, therapeutic applications usually require much larger doses because their purpose is to preferentially kill diseased tissues. For example, if a thyroid tumor were detected, a much larger infusion (thousands of rem, as opposed to a diagnostic dose of less than 40 rem) of iodine-131 could help destroy the tumor cells. Similarly, radioactive strontium is used to not only detect but also ease the pain of bone cancers. Table 1.1 “Some Radioactive Isotopes with Medical Applications” lists several radioactive isotopes and their medical uses.
Table 1.1 Some Radioactive Isotopes with Medical Applications
Isotope | Use |
---|---|
32P | cancer detection and treatment, especially in eyes and skin |
59Fe | anemia diagnosis |
60Co | gamma ray irradiation of tumors |
99mTc* | brain, thyroid, liver, bone marrow, lung, heart, and intestinal scanning; blood volume determination |
131I | diagnosis and treatment of thyroid function |
133Xe | lung imaging |
198Au | liver disease diagnosis |
*The “m” means that it is a metastable form of this isotope of technetium. |
In addition to the direct application of radioactive isotopes to diseased tissue, the gamma ray emissions of some isotopes can be directed toward the tissue to be destroyed. Cobalt-60 is a useful isotope for this kind of procedure.
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"عادة ليلية" قد تكون المفتاح للوقاية من الخرف
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ممتص الصدمات: طريقة عمله وأهميته وأبرز علامات تلفه
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المجمع العلمي للقرآن الكريم يقيم جلسة حوارية لطلبة جامعة الكوفة
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