Research Of ¹³¹I Treat Hyperthyroidism Dosimetry And Dynamic Evolution

Radioactive ¹³¹I treat hyperthyroidism is more commonly used in treatment of hyperthyroidism.After taking ¹³¹I, thyroid absorbs most of the ¹³¹I quickly. ¹³¹I emitsγ-ray andβ--ray,theβ-ray destroy the thyroid follicular cells,and kill the thyroid cells, so that resume the function of hyperthyroidism; while theγ-ray is through out of the body cause certain dose to the surrounding, make the medical staff and the public absorb additional irradiation.But theγ-ray emitted by ¹³¹I provides an effective means of research on the absorption, distribution, metabolism, and decayed of ¹³¹I in the body tissue and organs. This thesis research the absorption, distribution, metabolism, and decayed of ¹³¹I in different body tissue and organs according to the experiments of measuring radiation dose rate in vitro and mathematical model and calculation, analyse the curative effect of ¹³¹I, as well as the effects of radiation and radiation protection.In addition, We observed the curative effect of ¹³¹I taken by patients via measuring the level of the five main hormones for a long time, and analysed the factors that affect the curative effect. This thesis has also established a dynamic hypothyroid cell model for the ¹³¹I treat hyperthyroidism.Patients take the test dose of ¹³¹I to determine the treatment dose.we intensively measured the surface dose rate ofγ–ray of the thyroid, stomach, liver, bladder and other organs. We observed that different organs have different absorption of ¹³¹I and different attenuation, each of them shows a special absorption peak time and ¹³¹I absorption rate. ¹³¹I absorption rate of thyroid is the largest all of the organs, the peak of ¹³¹I absorption rate appears after ¹³¹I was taken 2⁴ hours. The dose rate of ¹³¹I for other organs is small so it caused little doses effects on other organs. According to pharmacokinetics two-compartment model, we have calculated out that the dose was absorbed and distributed by hypothyroid; the experimental and calculated results are almost consistent. Based on eight ¹³¹I treat hyperthyroidism cases of patients, with testing curative effect of ¹³¹I last for five months, we find out that hormone levels decrease in the way of the exponential and tend to normal levels. We attempt to set up a simple dynamic model about thyroid cell number evolution during using ¹³¹I treating hypothyroidism and we get a solution of that differential equation. According to the dynamic model thyroid cell number decay in the way of exponential during the treatment, the thyroid hormone is coincided with the exponential decay experimental results .Radiation damage of thyroid cells abide the general rules of the cell biological radiation effects, the thyroid cell death determined by the dose and dose rate of ¹³¹I. The dose rate caused by ¹³¹I is proportion to its activity. According to cell biological radiation effects, we have established dynamics mathematical mode according to the number of thyroid cells and get its solution. According to the model and its analytical solution, thyroid cell numbers decay following time, whose limit is the normal thyroid cells. Thyroid cells produce thyroid hormone, the level of thyroid hormone is approximately proportional to thyroid cells, and the model can better explain the curative effect of ¹³¹I.We observed two patients who take treatment dose and measured dose rate ofγ-ray in short distance for them. Our testing result shows that the dose rate close-up the patient is much higher than the environment's. Although some correlate statutes show that hyperthyroidism patients treated by ¹³¹I may not be in hospital. However, we should pay attention to the issue that the additional irradiation to his family members and the public close contacters. According to experimental data, we recommend patients with medication have a rest in Nuclear Medicine dedicated lounge for about a half-day and then go home. If patients take the public transport go home after therapy, they should keep away from others in distance avoid additional irradiation to others, also the same distance at home and better last for a week.This thesis through out clinical experiment find out that the hyperthyroidism curative effect of ¹³¹I basically shows via hormone(as T3,T4)and it exponential decay and tends to normal level. According to cells radibiological principles, we have established a mathematical model to describe the therapy curative effect of hyperthyroidism treated by ¹³¹I which have a better explain to clinical test results. This model can be used for some detail calculating and analysis, which will be carried out in the next step.