The therapeutic uses of radioisotope depend mainly on their ability to ionize atoms. Radioactive tracers are used to find out the diseased portion of the organ and the parts of the system.. Radioisotopes are used in medicines in two different ways.

• 1) Sources of radiation in therapy/ Therapeutic use
• 2) Radioactive tracers are used for diagnostic purposes/Diagnostic use

1. Chromium-51(sodium chromate Cr 51 injection):

It is used diagnostically to determine red blood cell mass, volume, and survival time, and for scanning the spleen. Chromium in the +6 oxidation state [Cr(VI)] is readily taken up by erythrocytes and becomes fixed to the globin portion of haemoglobin as chromium(III).

2. Cobalt -57 and 60 (Cyanocobalamin Co 60 Capsules and Solution)

They are used in diagnostic procedures for pernicious anaemia, the basis of the test suppose that if vitamin B12 is absorbed from the GIT, it will be excreted in the urine. Therefore, the radio activity from an oral dose of 60Co-labeled vitamin B12 should be detectable in the urine of the normal patient, and absent or at significantly lower levels
in the urine of the patient with pernicious anaemia.

Iron-59(Ferrous Citrate Fe 69 )

The isotope is employed in diagnostic procedures relating to various aspects of iron metabolism and red blood cell formation. The preparation can be administered orally to study the absorption of iron from the GIT, and injected intravenously for determinations of plasma iron clearance, turnover,
and the incorporation of iron into erythrocytes.

4.Gold-198(Gold Au 198 Injection)

Gold-198 solution is most frequently Used therapeutically. The solution is administered by intra cavitary injection into the pleural and peritoneal cavities as an aid in the management of pleural effusion and ascites .these fluid accumulations when secondary to neoplastic disease in the area .

5.lodine-125 and -131(Sodium Iodide I 125 Solution, Sodium Iodide I 131 Capsules and Solution)

Sodium iodide I131 is the most common isotope and chemical form in use as a diagnostic aid in the study of the functioning of the thyroid gland and in scanning the
thyroid to determine size, position, and possible tumour .
I131 is also employed therapeutically to destroy thyroid tissue .

6. Mercury-197 and 203(mercuric Hg 197,203 injection)

Chlormerodrin labelled with either 197Hg or 203Hg is a special radio-active tracer for making scintillation scans of the kidneys or the brain. This compound is in the chemical class of mercurial diuretics, which are generally taken up by the cells of the proximal kidney tubules in the renal cortex. The excretion from these cells is slow enough to allow scanning procedures of the kidneys to determine the presence and location of cysts, tumours, or other abnormalities.

7.Phosphorus-32(Sodium Phosphate P 32 Solution)

Solution is used for both diagnosis and treatment of various neoplastic diseases. Phosphate is utilized in cell metabolism. Those cells which are rapidly proliferating have the highest turnover of phosphate. Tumour cells are characterized as being rapidly proliferating, and will, therefore; accumulate phosphate labelled with 12P to a greater extent than non cancerous cells.

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