m-IBG therapy in neuroendocrine disease

21] and in neuroblastoma in 1984 [22].

Before treatment, any drugs known to interfere with the uptake and/or retention of ¹³¹I m-IBG must be withdrawn (EANM). A thyroid blocking agent must be prescribed, starting before and continuing for an extended period after treatment, to protect the gland from taking up any free ¹³¹I with the subsequent risk of developing hypothyroidism. The dose limiting toxicity is hematological and monitoring of blood counts is essential after treatment.

Iodine-123 m-IBG is available for imaging such tumours using a gamma camera and, as part of the preparation for treatment, patients should undergo m-IBG scintigraphy (either ¹²³I or ¹³¹I) to confirm uptake in all known tumour sites. Treatment may be prescribed either using a set activity, using an activity per kilogram or by using the results of pretreatment dosimetric measurements with a tracer dose. In this last case, an activity may be prescribed for treatment using a predetermined criterion. For instance, a limit of 2 Gy to the total body has been used in the treatment of children with neuroblastoma [23].

Typical administered activities are between 3.5 GBq and 7 G Bq and patients require admission to an isolation unit for a period of time determined by national regulations. Very careful arrangements must be made for the treatment and nursing of children, who are often under 3 years of age.

The effective dose to a 70 kg adult is 0.013 mSv/MBq, or 46 mSv for 3.5 GBq. The radiation dose to the tumour varies widely.

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