Treatment Administration

There are several routes of administration of radionuclide therapy (Table 2). The most commonly used is I-131 sodium iodide in capsule or liquid form. The recent development of the capsule form of sodium iodide has greatly increased convenience and decreased radiation safety issues. Liquid I-131 sodium iodide is highly volatile, requiring ingestion in a fume hood and putting hospital personnel at risk of contamination and thyroid I-131 burden. The I-131 oral capsules can be carried to the patient in the radioisotope laboratory in the clinic or hospital room in a properly shielded container. The simple procedure involves swallowing one to several capsules with water, with no contamination of the surroundings.

Intravenous administration of therapy agents requires careful observation and involvement of the staff and nuclear medicine physician. An intravenous line must be of a gauge that allows free flow of the radiopharmaceutical over a period of several minutes. The clinic or hospital floor personnel have to be prepared to identify and treat adverse reactions, and monitor the patient for up to several hours as well. In our clinics, treatments can only be administered in the direct presence of a nuclear medicine physician. Usually they are administered over several minutes so that if an adverse reaction develops, the administration can be interrupted. In some therapies, such as those using radiolabeled antibodies experimentally, the treatment infusions can last up to several hours requiring the use of an infusion pump with adjustable rate. In many cases, the dose is administered through an indwelling catheter. Most radioisotopes for therapy today do not have problems with adhesion to these lines, but it should be determined ahead of time if this is a potential problem, and a peripheral vein site selected. In some cases, the treatment syringe contains sufficient radioactivity that shielding is required to prevent a high hand dose to the personnel performing the therapy administration. Automated syringe pumps are also helpful in these situations, and can have the advantage of dose delivery at a smooth, predetermined rate.

Table 2 Routes of Administration in Radionuclide Therapy Oral

Intravenous Intracavitary Intra-articular Intracystic Intrathecal Intraperitoneal Subarachnoid

Intra-arterial (with catheterization)

Intracavitary treatment can be particularly interesting and rewarding in nuclear medicine practice. It varies somewhat from one practice to another depending on the patient and the referring physician mixture locally. More preparation and special procedure arrangement is often required for these therapies. Often the nuclear medicine physician performs these treatments with a practitioner of another specialty when specific skills are required. This is dependent on the level of skill and practice of the nuclear medicine physician. Examples are intra-articular and intraperitoneal treatments as well as the rare treatment of a cranial cyst. Whatever the intracavitary therapy, careful pretreatment planning and organization are very important for treatment success, patient safety, and radiation safety.

Intra-arterial treatments using radiocolloids and radiospheres are in practice in some locations. These are usually for treatment of hepatic tumors, and performed in conjunction with members of the angiography service. As angiography techniques become more widespread and sophisticated, intra-arterial therapies using particulate radiopharmaceuticals may become an important part of nuclear medicine practice.

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