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Logistical aspects
Patient preparation. Pregnancy and breast feeding are generally considered absolute contraindications for radionuclide therapy. Severe myelosuppression and severe renal failure are contraindications for 131I-MIBG therapy. Unstable patient condition not allowing isolation is considered as a relative contraindication.
Four to 6 weeks before 131I therapy thyroid hormone medication must be discontinued. A low-iodide diet for a period of 4-10 days before 131I administration is also recommended. Any other iodide-containing preparation (e.g. expectorants, kelp, agar, carrageen, Lugol's solution, potassium iodide solution, topical iodine, radiographic contrast agents) that potentially may affect 131I uptake must be discontinued or avoided.
With respect to 131I-MIBG drugs such as labetalol, reserpine, calcium-channel blockers, trycyclic antidepressants, ephinedrine, and adrenergic blocking agents may interfere 131I-MIBG uptake and must be discontinued before therapy. In order to prevent thyroid uptake of free 131I 100 (children) to 200 (adults) mg potassium iodide must be daily given from one day before 131I-MIBG to 2-3 weeks after treatment.
Concerning therapy with radiolabeled somatostatine analogues discontinuation in the administration of somatostatine analogues such as octreotide would be considered.
Radiopharmaceutical administration. Quality control of the used radiopharmaceuticals prior to the administration checking both the radionuclide and radiochemical purity is essential. Impurities will not contribute to the tumor targeting but may add to the side effects of such a treatment. Relatively high doses of radioiodinated pharmaceuticals such as MIBG with a high specific activity may undergo autoradiolysis (depending on the temperature, volume and presence of stabilizers and scavengers in the formulation) and too much free 131I (> 5%) may result in some radioiodine thyroid uptake despite blocking with potassium iodide.
Therapeutic 131I can be given in capsule or liquid form or is administered intravenously in patients who are prone to vomit. To increase salivary flow patients would be asked to chew gum or suck citrus sweets during the first 48 hours. Also hydration and at least one bowel movement daily are important to reduce bladder and colon radiation exposure.
For 131I-MIBG therapy the radiopharmaceutical is administered intravenously over 1 to 4 hours in 50-100 ml saline or glucose solution through a lead-shielding infusion system. Flushing of the line at the end of the infusion is necessary. Hydration of the patient following 131I-MIBG is important to reduce radiation exposure. Dibeniline and propanolol should be available in case of hypertensive crises in patients with pheochromocytoma. Often these patients are receiving these drugs in the week before 131I-MIBG therapy. In carcinoid patients octreotide by subcutaneous administration may be used in case of flushing. Anti-emetics not interfering with MIBG such as Motilium (Domperidon) may be used in case of nausea.
For therapy radiolabeled somatostatin analogues have been administered intravenously in infusion volumes of 80-100 ml over a period of 10 to 15 min. Co-infusion of amino acids have been recommended to reduce kidney uptake (29).
Isolation facilities. The availability and licensing of radiation protected isolation as well as the necessity of guidelines for radiation protection are important logistical factors to enable that radionuclide therapy becomes safe both for the patient and for relatives, personnel and the enviroment. An European survey demonstrated that there is considerable variation between countries in radionuclide therapeutic procedures, depending on local legislation and the requirement and availability of isolation facilities (30). Patients must be instructed how to reduce unnecessary radiation exposure to family members and members of the public. Particularly, when children need to be isolated, parents or other relatives are directly involved in child's patient care and need to be instructed for issues of radiation protection during isolation and in the period thereafter.
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