• The Korean Journal of Nuclear Medicine
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• v.37 no.6
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• pp.341-354
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• 2003

Radioactive iodine therapy using I-131 for hyperthyroidism has been used for more than 50 years, and generally considered safe and devoid of major side effects. Appropriate patient selection criteria and clinical judgement concerning patient preparation should be employed for its optimal use. It has not been possible to resolve the trade-off between efficient definite cure of hyperthyroidism and the high incidence of post-therapy hypothyroidism. The dose of the I-131 needed to maintain euthyroid state remains an area of uncertainity and debate. Early side effects are uncommon and readily managable. Other than the need for long-term monitoring and, in most cases, lifelong thyroid hormone treatment for late adverse consequences of this treatment remains only conjectural. We have reviewed general principles and recent advances in radioiodine treatment for Graves' hyperthyroidism, specially regarding to several controversies.

• Journal of radiological science and technology
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• v.33 no.3
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• pp.269-276
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• 2010

This study attempts to propose ways to optimize and improve the period of hospitalization for the radioiodine treatment by calculating the dose rate of patients treated with high-dose radioiodine by distance and time slot. As a result, 24 hours after the patient was treated with 100 mCi high-dose iodine, the dose rate was attenuated to $1,035{\mu}Sv/hr$ at the navel, to $109{\mu}Sv/hr$ at 50 cm, and to $33{\mu}Sv/hr$ at 100 cm. 24 hours after the patient was treated with 150 mCi high-dose iodine, the dose rate was attenuated to $637{\mu}Sv/hr$ at the navel, to $100{\mu}Sv/hr$ at 50 cm, and to $40{\mu}Sv/hr$ at 100 cm. 24 hours after the patient was treated with 180 mCi high-dose iodine, the dose rate was attenuated to $1,251{\mu}Sv/hr$ at the navel, $140{\mu}Sv/hr$ at 50 cm, and to $56{\mu}Sv/hr$ at 100 cm. In light of the current criterion for discharge recommended by the US Nuclear Regulatory Commission being $70.4{\mu}Sv/hr$, the present study indicates earlier discharge is feasible by applying a new scheme. This suggests that the proposed scheme in this study will help to solve the problem of shortage of treatment beds with the increasing trend of patients with thyroid cancer taken into consideration.

• The Korean Journal of Nuclear Medicine
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• v.1 no.1
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• pp.67-78
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• 1967

Over the past 6 years, from May 1960 to June 1966, 1,716 patients with various diseases of thyroid were examined and thyroid function tests with $^{131}I$ were done. Among them, 545 patients with hyperthyroidism were treated with $^{131}I$. A summary of the clinical data of the $^{131}I$-thyroid function tests and the therapeutic results of $^{131}I$ were presented and discussed. 1. The patients examined consisted of; 596 cases(34.7%) with toxic diffuse goiter, 412 cases(24.0%) with non-toxic nodular goiter, 278 cases(16.2%) with euthyroidism, 236 cases(13.8%) with non-toxic diffuse goiter, 89 cases(5.2%) with hypothyroidism, 53 cases(3.1%) with toxic nodular goiter, 32 cases(1.9%) with thyroiditis and 20 cases(1.2%) with dyshormonogenesis. 2. There were 218(12.7%) male patients and 1,498(87.3%) female patients, showing a ratio of 1:6.9. female predominantly. 3. The majority of patients(79.6%) were in the 3rd through 5th decades of their lives showing the peak in the 4th decades(35.9%). 4. The diagnostic values and normal ranges of $^{131}I$ uptake test, 48 hour serum activity, $T_3$ red blood cell uptake and $PB^{131}I$ conversion ratio were discussed. 5. An attention was given to dyshormonogenesis, a qualitative hypothyroidism, due to its characteristic findings of clinical and $^{131}I$ thyroid function tests, and its pathogenesis was briefly reviewed. 6. Among 545 patients with hyperthyroidism treated with $^{131}I$, 68.3% was cured after single. therapeutic dose and another 24.0% was cured after second dose. 7. The complications of $^{131}I$ therapy were discussed in some details and myxedema had developed. in 3.9% of our cases. No thyroid cancer was found after $^{131}I$ therapy.

• Journal of radiological science and technology
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• v.31 no.1
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• pp.11-16
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• 2008

Purpose : The aim of this study was to predict radiation dose at 1 meter with BMI(body mass index) in thyroid cancer patients treated with radio-iodine and provide the efficient guideline in the management of patients. Methods : 140 patients from thyroidectomy for thyroid cancer were enrolled. All subjects under went 150 mCi radio-iodine therapy and performed whole body scan 1 week later. BMI(weight divided by square of height) was calculated to evaluate the amount of fatty tissue indirectly. The radiation dose at 1 meter was measured initially and on 2nd days. the relation of values with BMI were analyzed statically. As for the method of statistical analysis, using Med calc Version 9,2,2,0 Program. Results : (1) The initial effective dose was inversely correlated with the BMI. Significance level was 0.0004. (2) We obtained the following formula from the data of initial effective dose and BMI: Y = -30.91X + 350.4(${\mu}Sv/h$)(Y: initial radiation dose, x: Group). (3) After 21.55 hours, than radiation dose was less than those recommended by ICRP or NRC in 53% of the population. Conclusion : Using BMI, the initial radiation dose and 2nd days dose can be predicted in thyroid cancer patients before radio-iodine therapy. It may be used for predicting the time of discharge and control the isolation room. We were able to predict the radiation exposure after discharge using this calculated value.

• The Korean Journal of Nuclear Medicine
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• v.34 no.2
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• pp.107-118
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• 2000

Purpose: To evaluate the effectiveness of radioiodine treatment for metastatic thyroid carcinoma, we reviewed results of radioactive iodine treatment in patients with functional lung or bone metastases. Materials and Methods: Of 760 patients who were treated for differentiated thyroid cancer between 1984 and 1998, we detected pulmonary metastases and bone metastases in 76 patients (10.0%) and 20 patients (2.6%), respectively. Among them, we could evaluate the effectiveness of I-131 therapy in 53 patients with lung metastases and 15 patients with bone metastases. Results: Of 53 patients who received I-131 therapy with a mean cumulative dose of 26.2 GBq (1.1-84.4 GBq) for pulmonary metastases, metastatic lung lesions completely resolved in 19 patients (35.8%) and improved in 22 patients (41.5%). In 13 of 19 patients with complete remission of pulmonary metastases, the total accumulated dose of I-131 was less than 18.5 GBq. We found 43 sites of metastatic bone lesions in 15 patients with bone metastases. Of 29 lesions which received I-131 therapy, metastatic lesions improved in 14 sites (48.3%), but did not change or progress in 15 sites (51.7%) despite the I-131 therapy. Three lesions were completely cured with a combination treatment of surgery(${\pm}$ external radiotherapy) and I-131 therapy, and the other 11 lesions improved. Conclusion: Radioactive iodine treatment gives favorable results for pulmonary metastases. However, for bone metastases, there might be a need to use combination therapy including I-131 and surgery or external irradiation.

• The Korean Journal of Nuclear Medicine
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• v.34 no.4
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• pp.285-293
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• 2000

Purpose: A prospective comparison was made between imaging with Tc-99m pertechnetate (Tc-99m) and Ioine-131 (I-131) for the detection of residual and metastatic tissue after total thyroidectomy in patients with well-differentiated thyroid carcinoma. Materials and Methods: Initially our patients had imaging with Tc-99m, followed by I-131 within 3 days. The study included 21 patients who had ablation with high dose of I-131 ranging from 100 mCi to 150 mCi. Planar and pinhole images were acquired for both Tc-99m and I-131. Diagnostic images of Tc-99m and I-131 were compared with post-therapy images. Degree of uptake on Tc-99m and I-131 images was scored by four point scale and compared. Results: The results of the Tc-99m study were: 16 of 19 studies (84%) were positive on simple planar images, but 19 of 20 studies (95%) were positive on pinhole images. Conventional I-131 diagnostic imaging on the other hand showed that all studies (100%) were positive on both planar and pinhole images. There was a significant difference in degree of uptake between Tc-99m and I-131 planar images (p<0.05). Only one case of Tc-99m scintigraphy was negative on both planar and pinhole studies (false negative). There was no distant metastasis on the therapeutic I-131 images. Conclusion: Tc-99m scan using pinhole in certain clinical situations is an alternative to the I-131 scan in detecting thyroid or lymph node metastasis prior to the first ablative treatment after thyroidectomy for well-differentiated thyroid carcinoma.

• Journal of the Korean Society of Radiology
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• v.11 no.7
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• pp.597-603
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• 2017

High-dose $^{131}I$ therapy has been generally carried out to remove remaining thyroid tissue or to cure metastasize lesion of patients who received full thyroidectomy due to differentiated thyroid cancers. In case high-dose $^{131}I$ therapy is carried out for a patient, the patient should be hospitalized being isolated for a certain period in order to restrict the amount of exposure to radiation of people at large from the patient within the limit of a level of radiation. Effective half-life is an important value to calculate how family members are exposed to radiation from a patient or to decide the period of isolation of the patient from the family members. Therefore, in this study we calculated the effective decay constant, effective half-life and period of isolation of high-dose $^{131}I$ therapy patient using NM670 SPECT/CT. As a result of carrying out this study, the effective half-life of high-dose $^{131}I$ therapy patients was derived and the time to reach the discharge level of 1.2 GBq was confirmed. When they were compared with each other in each of curative doses, the effective half-life did not have significant difference, but the time when the level of radiation remaining in the interior of the body to reach the criteria of isolation and discharge showed significant difference and it could be confirmed that the higher the curative dose the longer the period of isolation becomes. When the effective half-lives in each type of preparation were compared with each other, they did not show significant difference. However, When the times to reach the level of radiation that is the criteria of isolation and discharge in each type of preparations, they showed significant difference. The cause of the shortening of the isolation period for rhTSH patients group is decided to be low curative dose. Accordingly, if the current national health insurance (the insurance is applied to using of rhTSH in 3.7 GBq or lower) is maintained, while discerning them in each of types of preparation, we would be able to discharge patients at the time earlier than the current period of isolation (2 nights and 3 days).

• Nuclear Medicine and Molecular Imaging
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• v.40 no.6
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• pp.322-326
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• 2006

A low iodine diet (LID) for $1{\sim}2$ weeks is recommended for patients who undergoing radioiodine remnant ablation. However, the LID educations for patients are different among centers because there is no concrete recommendation for protocol of LID. In this investigation, we compared two representative types of LID protocols performed in several centers in Korea using urine iodine to creatinine ratio (urine I/Cr). Methods: From 2006, April to June, patients referred to our center for radioiodine remnant ablation of thyroid cancer from several local hospitals which had different LID protocols were included. We divided into two groups, stringent LID for 1week and less stringent LID for 2 weeks, then measured their urine I/Cr ratio with spot urine when patients were admitted to the hospital. Results: Total 27 patients were included in this investigation (M:F=1:26; 13 in one-week stringent LID; 14 in two-week less stringent LID. Average of urine I/Cr ratio was $127.87{\pm}78.52{\mu}g/g$ in stringent LID for 1 week, and $289.75{\pm}188.24{\mu}g/g$ in less stringent LID for 2 weeks. It was significantly lower in stringent LID for 1 week group (p=0.008). The number of patients whose urine I/Cr ratios were below $100{\mu}g/g$ was 6 of 13 in stringent LID for 1 week group, and 3 of 14 in less stringent LID for 2 weeks group. Conclusion: Stringent LID for 1 week resulted in better urinary I/Cr ratio in our investigation compared with the other protocol. However it still resulted in plenty of inadequate range of I/Cr ratio, so more stringent protocol such as stringent LID for 2 weeks is expected more desirable.

• The Korean Journal of Nuclear Medicine
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• v.4 no.2
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• pp.29-39
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• 1970

A summary of the clinical data of the $^{131}I$-thyroid function tests and the therapeutic results of $^{131}I$ among the 2,658 patients of various thyroid diseases treated over the past 10 years from May 1960 to Oct. 1969 at the Radioisotope Clinic and Laboratory, SNUH were presented and dscussed. 1. The patients examined consisted of: 929 cases (34.9%) of diffuse toxic goiter, 762 cases (28.7%) of diffuse nontoxic goiter, 699 cases (26.3%) of nodular nontoxic goiter, 58 cases (2.2%) of nodular toxic goiter and 210. cases (7.9%) of hypothyroidism. 2. There were 300 (11.4%) male and 2358 (88.6%) female, showing a ratio of 1:8. 3. The majority of patients (79.1%) were in the 3rd-5th decades of their lives. 4. The normal ranges, diagonstic values of $^{131}I$ uptake test, 48 hrs, serum activity, BMR and main subjective symptoms of various thyroid diseases were discussed. 5. In the 579 patients among 867 cases with hyperthyroidism treated with $^{131}I$, 47.8% were confirmed to be cured completely after single therapeutic doses. 6. The complications of $^{131}I$ therapy were discussed and myxedema had developed in 6.75% of our patients. 7. The results of $^{131}I$ thyroid function tests were analysed among the 160 cases of thyroid diseases which were confirmed the diagnosis with histopathological measures.

• The Korean Journal of Nuclear Medicine
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• v.3 no.1
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• pp.51-58
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• 1969

To clarify the hematologic effects of the radioiodine ($^{131}I$) in therapeutic doses ($5{\sim}10$ mCi) on the various thyroid patients, authors studied the peripheral blood pictures of 396 goitrous patients before and after radioiodine ($^{131}I$) administrations in the Isotope Clinic of Seoul National University Hospital. Among these 396 cases of goiters, we gave 5 to 10 mCi of radioiodine ($^{131}I$) with single or fractionated administrations. The blood pictures of peripheral blood were repeated after 3 months in 40 cases of 65 cases who had been treated with $^{131}I$. The blood pictures of non-treated thyroid patients were compared with that of normal Korean values to clarify any difference between normal and goiter. The blood pictures of hyperthyroid patients treated with $^{131}I$ therapy were compared with the blood pictures of non-treated thyroid patients. The results were as following: 1) The incidence according to type: Toxic diffuse goiter: 35.4% Nontoxic nodular goiter: 29.7% Euthyroid: 13.8% Nontoxic diffuse goiter: 12.6% Hypothyroidism: 4.3% Thyroiditis($\bar{s}$ subacute form): 1.8% Toxic nodular goiter: 1.4% Malignancy: 1.0% 2) Age incidence: The range of distribution was 11 to 71 years. The peak incidence was found in the 4th decade of life. $80.6{\sim}82.6%$ of those 396 cases were found among the 3rd, 4th and the 5th decades of life. 3) Sex incidence: Sex ratio of male:female was 1:7.8. 4) The most outstanding findings in peripheral blood before treatment were decreased erythrocyte count and hemoglobin value in all types of thyroid diseases, especially in. the cases of hypothyroidism and thyroiditis. Hook worm-infested patients showed no significant difference in erythrocytes and hemoglobin values from those of other hook worm free patients. 5) Total leukocytes count was within normal range. Differential count of W.B.C. showed increased percentile of lymphocyte in diffuse toxic goiter and thyroiditis. 6) 39 cases of diffuse goiter treated with $^{131}I$ toxic showed amelioration in the anemia and restoration to normal range of lymphocyte count in association with increased percentile of neutrophiles 3 months after administration, except a case of toxic nodular goiter. One can observe anemia in slight degree, and increased lymphocytes count in hypothyroidism. Therapeutic dose of radioiodine ($^{131}I$) does not result any residual effect on the hematopoietic function. Radioiodine ($^{131}I$) therapy resulted in improvement of thyroid function in association of amelioration of pevious abnormal blood pictures. 7) Authors did not observe any myxedema resulted from radioiodine therapy during the 3 months period in this study.