How is radioisotope scan test done?

As already stated, radioisotope scan relies on information obtained from a radiation source inside the human body. Therefore, the radiopharmaceutical as it is called, has to be introduced inside the human body. This can be done in many ways-

Injection into a vein with the help of a needle (usually the inside of the elbow)
Through a synthetic tube inserted into a blood vessel (artery or vein) which is then directed to the organ of interest.
Through Ingestion- in the form of a pill which the patient swallows.
Injection under the skin

The mode of administration of the radioisotope would differ depending on the organ to be studied. For example, to image iodine, the patient may be asked to swallow a tablet and for imaging of the kidney, the patient is usually given the medication in the form of an intravenous injection.