Re-HEDP : pharmacokinetic characterization, clinical and dosimetric evaluation in osseous metastatic patients with two levels of radiopharmaceutical dose

BACKGROUND: A study for pain relief therapy with (188)Re-HEDP was done in patients with bone metastases secondary to breast and prostate cancer. MATERIALS AND METHODS: Patients received 1.3 or 2.2 GBq, in single or multiple doses. Platelets, white and red cells were evaluated during 11 weeks. Pharmacokinetic characterization was done from blood and urine samples for 5 patients along 24 hours. Urinary excretion was evaluated in other 16 patients during 6 hours. Bone uptake was estimated as remaining activity in whole body. Scintigraphic images were acquired at 2 and 24 hs post-administration. Absorbed dose in bone marrow was estimated with Mirdose3. Analgesics intake and pain score were daily recorded. Tumour markers (PSA, and Tn-structure) were monitored in 9 patients during 4 to 6 months. Single doses of low activity (1.3 GBq) were given to twelve patients. Nine patients received multiple doses. RESULTS: All except one patient had normal levels of platelets, white and red cells. Remaining dose in blood at 2 hours was 9%. Urinary elimination was 58%. Bone uptake at 24 hours was 43% (mean value; n = 5). No changes of the haematological parameters were detected along follow-up period. Pain relief was evidenced by decrease or supression of opioid analgesic and by subjective index. PSA showed a decrease in prostate cancer patients (n = 4). Tn-structure showed a significant increase after 4 to 8 months. CONCLUSION: Single or multiple dose scheme could be safely used, with administered activity of (188)Re-HEDP up to 60 mCi, with low bone marrow absorbed doses

Practical Dosimetry of 131I in Patients with Thyroid Carcinoma

Radioiodine treatments of patients with well-differentiated thyroid carcinoma have generally been safe and beneficial. Safety can be ensured while efficacy is increased through practical methods of dosimetry that measure body retention of 131I. Prescriptions for therapeutic 131I can be decreased when the retention level is high and increased when the level is low. Assays of serum free T4 will alert the physician to possible increased radiation to blood and bone marrow, and appreciable concentrations of free T4 are indications to reduce the therapeutic 131I. Carcinomas ≥1 cm in diameter that are not visible on diagnostic scintigraphy are unlikely to respond to the commonly prescribed mCi of 131I. Biologic responses to commonly prescribed levels of therapeutic 131I, as seen in toxic changes of normal tissues and in indices of tumor size, will be the final dosimeters. With lower levels of prescribed diagnostic 131I, stunning should not impair dosimetry. Thus, readily obtained measurements make dosimetry a practical method for improving carcinoma therapy with 131I.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63166/1/10849780252824118.pd

Therapeutic Radionuclides: Making the Right Choice

Recently, there has been a resurgence of interest in nuclear medicine therapeutic procedures. Using unsealed sources for therapy is not a new concept; it has been around since the beginnings of nuclear medicine. Treatment of thyroid disorders with radioiodine is a classic example. The availability of radionuclides with suitable therapeutic properties for specific applications, as well as methods for their selective targeting to diseased tissue have, however, remained the main obstacles for therapy to assume a more widespread role in nuclear medicine. Nonetheless, a number of new techniques that have recently emerged, (e.g., tumor therapy with radiolabeled monoclonal antibodies, treatment of metastatic bone pain, etc.) appear to have provided a substantial impetus to research on production of new therapeutic radionuclides. Although there are a number of new therapeutic approaches requiring specific radionuclides, only selected broad areas will be used as examples in this article