---

Introduction: Increased prevalence of thyroid cancer has been noted in patients with a previous history of radiotherapy of the head and neck region in childhood. According to previous research, radiotherapy for Tinea Capitis was used for 30 years (1945-1975) in Khorasan province. This study has tried to evaluate the prevalence of benign and malignant thyroid nodules and to detect and treat affected patients earlier to prevent further complications and costs. Material and methods: Using mass media, we recalled all patients with history of radiotherapy for Tinea Capitis in childhood. A questionnaire was filled out for each patient and thyroid examination, thyroid scan and thyroid sonography were performed. Fine needle aspiration biopsy (FNAB) was done if a thyroid nodule larger than 1 cm was palpable. Serum TSH was measured in all patients. Also thyroid surgery was recommended for all patients with thyroid nodules of more than 1 cm. A control group were selected from a group of patients referred for non thyroidal sonography to the radiology department of Ghaem Hospital. These patients also were evaluated by clinical examination and thyroid sonography. We studied 180 patients with a mean age of 47.5 years and 127, age and sex matched controls. Results: Thyroid nodules were palpable in 45.5% of patients and 7% of controls (p<0.01). Ultrasonography also detected thyroid nodules in 51.2% of patients and 26.1% of the controls (p<0.01). The largest mean diameter of nodules were 24.8 mm in patients and 10.8 mm in the control group (p<0.001). 73.1% of patients agreed to FNAB and 5% of them had suspicious cytology results. No suspicious or malignant results were noted in the control group. Twenty-seven patients (33.7%) were operated. Pathological results were benign in 89.9% and malignant in 11.1% of patients. This study showed that thyroid nodules and thyroid neoplasm were significantly more frequent in patients in comparison with control group, the thyroid nodules being larger in size in the patient group. Thyroid neoplasms were more frequent among younger patients with a latent period (from radiotherapy) of less than 40 years. Conclusion: Aggressive evaluation is recommended in these groups.

---

Abstract Introduction: Cytological radiation damage to lymphocytes can result in augmentation of cells with micronuclei. In this study we investigated cytological radiation damage to peripheral blood lymphocytes using the micronuclei assay (MNA) method. Considering the value of Iodine-131 in diagnostic and therapeutic nuclear medicine and high absorbed dose of I131 radioiodine in comparison with gamma emitters and the effect of type of radiation, dose and species on radiosensitivity of patients, this study was conducted. To evaluating the cytological radiotoxicity of therapeutic radiotracers such as radioiodine I131. Materials and Methods: We studied 22 patients with differential thyroid carcinoma who were referred for treatment with 100 or 150 mci I131. Before and one weak after treatment the peripheral lymphocytes were harvested and isolated by a cytological method and assayed for frequency of micronuclei as a marker of cytological radiotoxicity. Results: The means of micronuclei in one hundred binuclear lymphocytes were 6.3±2.2 before treatment and and 9.6±3.1 after treatment, differences in the number of micronuclei being statistically significant (p value <0.05). Conclusions: High doses of radioiodine therapy used after surgery for differentiated thyroid carcinoma can increase micronuclei among peripheral lymphocytes as an indirect marker of chromosomal aberrations and cytotoxic radiation damage.

---

Introduction: On the 25th anniversary of the Chernobyl power plant accident, interest was rekindled by the recent Japan nuclear disaster, and the medical consequences from the fall out are once again under scrutiny. In a nuclear power plant, the fuel, is an isotope of either Uranium or Plutonium. In the event of an accident, radioactive elements escape into the environment. By far the most dramatic accidents occurred at the Chernobyl nuclear power plant in 1986 and at the Fukushima nuclear power plant of Japan on March 11, 2011. A major health hazard of a nuclear accident is childhood thyroid cancer which can be avoided if stable iodine is administered as prophylaxis during the hours immediately following the accident and particularly in young children. Early administration of iodine is critical because it is not as useful if taken six hours after radiation exposure. Prior to 1986 the usefulness of this prophylaxis was controversial since there was limited data on is potential carcinogenic risks. At present, however there is no doubt that prophylaxis with potassium iodide (KI) with limited consumption of contaminated food is not harmful and useful if administered promptly.