Use Of Iodine-131 Research Articles

Guidelines on the Release of Patients Treated with Iodine – 131 for Thyroid Cancer in Nuclear Medicine: Case of Madagascar

The most frequently used radiopharmaceutical for treatment of thyroid cancer is the radioactive iodine (RAI). Patients treated with RAI therapy cause risk of external radiation exposure to the public and family members. While the therapeutic use of iodine-131 for thyroid carcinoma patients offers enormous benefit to them, it contributes also significantly to the radiation exposure of individuals and population. Patients treated with radioiodine present a radiation hazard and precautions are necessary to limit radiation dose to the relatives and the members of the public. The study aims to develop guidelines for the release of thyroid cancer patients treated with I-131. For this purpose, simulations were performed for estimating suitable period of restriction during which close contact with the patient should be disallowed and limited. These simulations are based on the French working Group and the recommendations of the International Commission on Radiation Protection. The study was carried out at the Isotopes Laboratory (LRI), Department of Nuclear Medicine in Antananarivo, Madagascar. According to the current regulation in radiation protection in Madagascar, the dose limit for the members of the public is limited to 1 mSv. Guidelines for discharge from the hospital are as follows. Patients can travel using public transportation up to 15 minutes. Patients are suggested to sleep apart and restrict contact with partner for 4 days after leaving the hospital. Contact with children should be restricted according to their ages. Time to restrict contact with child ranging from 3 to 10 years is limited to 4 days, and up to 7 days for younger children. This guideline is based on the retained activity of 800 MBq or the external dose rate is less than 40 μSv/h at 1 m. For public transportation, the suggested travel times for thyroid cancer are similar to those recommended by the French group. The length of time for which patients are in contact with children in this study is widely less than recommendations by French Group.

Clinical Advances and Perspectives in Targeted Radionuclide Therapy.

Targeted radionuclide therapy has become increasingly prominent as a nuclear medicine subspecialty. For many decades, treatment with radionuclides has been mainly restricted to the use of iodine-131 in thyroid disorders. Currently, radiopharmaceuticals, consisting of a radionuclide coupled to a vector that binds to a desired biological target with high specificity, are being developed. The objective is to be as selective as possible at the tumor level, while limiting the dose received at the healthy tissue level. In recent years, a better understanding of molecular mechanisms of cancer, as well as the appearance of innovative targeting agents (antibodies, peptides, and small molecules) and the availability of new radioisotopes, have enabled considerable advances in the field of vectorized internal radiotherapy with a better therapeutic efficacy, radiation safety and personalized treatments. For instance, targeting the tumor microenvironment, instead of the cancer cells, now appears particularly attractive. Several radiopharmaceuticals for therapeutic targeting have shown clinical value in several types of tumors and have been or will soon be approved and authorized for clinical use. Following their clinical and commercial success, research in that domain is particularly growing, with the clinical pipeline appearing as a promising target. This review aims to provide an overview of current research on targeting radionuclide therapy.

INVESTIGATION OF THE INFLUENCE OF THYROID LOCATION ON IODINE-131S VALUES.

The use of iodine-131S values based on reference computational phantoms with fixed thyroid model may lead to significant dosimetric errors in patients who may have different thyroid location from the reference phantoms. In the present study, we investigated individual thyroid location variation by examining the computed tomography image sets of 40 adult male and female patients. Subsequently, the thyroid location of the adult male and female mesh-type reference phantoms of the International Commission on Radiological Protection (ICRP) was adjusted to match each the highest, mean and the lowest locations of the thyroid observed in this dataset. The thyroid-adjusted phantoms were implemented into the Geant4 Monte Carlo code to calculate thyroid location-dependent iodine-131S values (rT←thyroid) for a total of 30 target regions. The maximum variation among the observed thyroid locations was 39mm and 36mm for male and female patients, respectively. The mean thyroid locations of both male and female patients showed a good agreement with the ICRP reference phantoms. The thyroid location-dependent Iodine-131S values were significantly different from the reference phantoms for most target regions by up to a factor of 3. The use of thyroid location-dependent S values in dose reconstructions should help quantify the dosimetric uncertainty in epidemiologic investigations of patients receiving iodine-131 therapy for hyperthyroidism and thyroid cancer.

Use of Iodine-131 to Tellurium-132 Ratios for Assessing the Relationships between Human Inhaled Radioactivity and Environmental Monitoring after the Accident in Fukushima.

Significant differences in findings were seen between the intake amounts of iodine-131 that were derived from direct measurements and the estimated intake from environmental monitoring data at the Fukushima accident. To clarify these discrepancies, we have investigated the iodine-131 and tellurium-132 body burdens of five human subjects, who after being exposed to a radioactive plume, underwent 21.5 h whole body counter measurements at Fukui Prefectural Hospital, so clear intake scenario and thyroid counter measurement data were available. To determine the iodine-131 and tellurium-132 body burdens, we introduced a new method of whole body counter calibration composed of a self-consistent approach with the time-dependent correction efficiency factors concept. The ratios of iodine-131 to tellurium-132, ranging from 0.96 ± 0.05 to 2.29 ± 0.38, were consistent with results of the environmental measurements. The 24 h iodine uptake values ranging from 12.1–16.0% were within euthyroid range in Japanese people. These results suggest, even if the relatively low thyroid iodine uptake in the Japanese population was taken into consideration, that there is no doubt about the consistency between direct measurements and environmental monitoring data. Adequate intake scenario is suggested to be principally important to estimate the inhaled radioactivity in areas in or around nuclear accidents.

ACR–ASTRO Practice Guideline for the Performance of Therapy With Unsealed Radiopharmaceutical Sources

This guideline is intended to guide appropriately trained and licensed physicians performing therapy with unsealed radiopharmaceutical sources. Adherence to this guideline should help to maximize the efficacious use of these procedures, maintain safe conditions, and ensure compliance with applicable regulations. The topics dealt with in this guideline include indications for the use of iodine-131, both for the treatment of hyperthyroidism and thyroid carcinoma. In addition, indications for other less common procedures include those for the use of phosphorous-32 in its liquid and colloidal forms, strontium-89, samarium-153, and the use of Y-90 antibodies.

Irradiations de la thyroïde et cancers thyroïdiens: Revue bibliographique critique

The large increase in the incidence of thyroid cancer among children who were mainly less than five years old at the time of the Chernobyl accident is still a major concern for endocrinologists and nuclear medicine physicians. Epidemiological studies have focused solely on iodine-131. However, past knowledge on thyroid irradiation (medical use of iodine-131, radioactive fallout on Marshall islands and the Nevada and Hanford site releases) as well as number of recent works (about low-dose irradiation) raise question on the role of other factors. It is here shown that post-Chernobyl thyroid irradiation is complex and that all factors (iodine-131, but also short lived isotopes of iodine and external irradiation) should be considered. Finally, one needs to think about some of the present medical uses of iodine-131 and especially to the treatment of hyperthyroidism in young subjects.

Proposición de consenso para el uso de yodo 131 en el tratamiento de la tirotoxicosis y el cáncer del tiroides

A consensus meeting held by the Chilean Endocrinological Society reached to 22 consensus proposals on the use of iodine-131 in hyperthyroidism and thyroid cancer, that are reported in this paper. Some of these propositions are: 1) Hyperthyroidism: A previous 131I uptake test must be performed. A calculated or an ablative dose should be administered. Hypothyroidism must be considered an objective rather than a complication. In patients with cardiovascular risk, normal thyroid function must be attained with prophythioturacil. In cases of treatment failure, the dose should not be repeated before six months. It must be used with used with caution in children and teenagers. 2) Thyroid cancer: A iodine free diet is recommended prior to the therapeutic dose. A 100 mCi complementary ablative dose should be given after surgery, with a posterior exploration. This examination must not be done routinely, and if required, a 5 mCi dose should be used. For the treatment of metastases, a dose of 150 to 200 mCi is recommended. There is no radiation risk in hyperthyroidism or thyroid cancer. The only absolute contraindication is pregnancy. Recommendations for radiological protection are formulated. Hospitalization is suggested to protect other people from radiation exposure.

Galanin gene expression in radiothyroidectomy-induced thyrotroph adenomas.

Galanin gene expression is markedly increased in the anterior pituitary glands of estrogen-treated rats (lactotroph hyperplasia) as well as human growth hormone-releasing hormone transgenic mice (somatotroph hyperplasia). The objective of this study was to examine galanin in a mouse model of thyrotroph adenoma formation. Male mice were radiothyroidectomized by use of iodine-131 (131I), and galanin peptide levels were assessed in the hypothalamic-pituitary axis. Immunoreactive galanin concentrations in the anterior pituitaries of 131I-treated mice were decreased 80% at 3, 6, 9, and 12 mo after radiothyroidectomy. Galanin peptide levels in the hypothalamus were decreased 20-25% at these times. Treatment with either estradiol or 3,3',5-triiodo-L-thyronine increased galanin peptide concentrations in the anterior pituitaries of 131I-treated mice, but neither treatment restored galanin concentrations. Galanin mRNA levels were decreased > 80% 1 yr after radiothyroidectomy. We conclude that, unlike animal models of lactotroph and somatotroph hyperplasia, galanin gene expression is suppressed throughout the development of thyrotroph adenomas, suggesting that galanin does not have a stimulatory role in the proliferation of thyrotrophs. Moreover, these data show that thyroid hormones are important positive regulators of galanin gene expression in the mouse and that estrogen may stimulate galanin gene expression in the absence of thyroid hormones.

Thyroid Cancer

There have been important recent advances in our understanding of the biologic nature of thyroid cancer and in the early diagnosis of the disease. Despite these advances, there is still considerable controversy over the management of thyroid cancer, including the extent of surgery, the indications for the use of iodine-131, the effectiveness of thyroid-stimulating hormone suppression, and the prediction of outcome. In this review, the current status of the diagnosis and management of the various types of thyroid cancer are carefully reviewed and extensively documented.

Effect of Processing upon Concentration and Distribution of Natural and lodophor-Derived Iodine in Milk

Cream removal, pasteurization, and spray-drying of milk did not affect concentration of either natural or iodophor-derived iodine, as measured by both chemical and electrode methods, although electrode results were significantly higher. The use of iodine-131 labeled iodophor showed that only .02% of iodine was lost from milk on boiling and that 3.4% of iodophor-iodine became associated with milk casein.

Use of iodine-131 to measure movements of small animals.

A technique utilizing iodine-131 was developed to study the movements of Microtus pennsylvanicus in the field. Iodine-131 ((1/2) mc) was placed in a polyethylene capsule and inserted beneath the animal's skin. Movements of the animal were then followed for periods of up to 2 weeks by means of a Geiger-Müller counter attached to an aluminum pole.

The Calibration and Standardization of Thyroid Radioiodine Uptake Measurements

The use of iodine-131 for the assessment of thyroid function by means of the 24-hour uptake determination is discussed from the point of view of standardization of procedure.Recommendations are made about the amount of the tracer dose, the method of its administration, the use of standards and phantoms, the type of detecting equipment and the position of the patient.

Chloric Acid Method for Determining Protein-Bound Iodine by Use of Iodine-131

Chloric Acid Method for Determining Protein-Bound Iodine by Use of Iodine-131