• The Korean Journal of Nuclear Medicine
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• v.33 no.4
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• pp.422-429
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• 1999

Purpose: The measurement of radiation absorbed dose is useful to predict the response after I-131 labeled metaiodobenzylguanidine (MIBG) therapy and determine therapy dose in patients with unresectable or malignant pheochromocytoma. We estimated the absorbed dose in tumor tissue after high dose I-131 MIBG in a patient with pheochromocytoma using a gamma camera and Medical Internal Radiation Dose (MIRD) formula. Materials and Methods: A 64-year old female patient with pheochromocytoma who had multiple metastases of mediastinum, right kidney and periaortic lymph nodes, received 74 GBq (200 mCi) of I-131 MIBG. We obtained anterior and posterior images at 0.5, 16, 24, 64 and 145 hours after treatment. Two standard sources of 37 and 74 MBq of I-131 were imaged simultaneously. Cummulated I-131 MIBG uptake in tumor tissue was calculated after the correction of background activity, attenuation, system sensitivity and count loss at a high count rate. Results: The calculated absorbed radiation dose was 32-63 Gy/ 74 GBq, which was lower than the known dose for tumor remission (150-200 Gy). follow-up studies at 1 month showed minimally reduced tumor size on computed tomography, and mildly reduced I-131 MIBG uptake. Conclusion: We estimated radiation absorbed dose after therapeutic I-131 MIBG using a gamma camera and MIRD formula, which can be peformed in a clinical nuclear medicine laboratory. Our results suggest that the measurement of radiation absorbed dose in I-131 MIBG therapy is feasible as a routine clinical practice that can guide further treatment plan. The accuracy of dose measurement and correlation with clinical outcome should be evaluated further.

• The Korean Journal of Nuclear Medicine
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• v.14 no.2
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• pp.35-40
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• 1980

In order to compare the therapeutic effect as well as side effects between antithyroid therapy and radioiodine therapy in hyperthyroidism, the author evaluated 111 cases of hyperthyroidism which were composed of 57 patients with antithyroid treatment, 23 patients with combined treatment comprising of antithyroid and radioactive iodine ($^{131}I$) and 31 patients with treatment of $^{131}I$ alone. The $^{131}I$ treatment was limited to older age, above 20 years of age, and not employed in patients with pregnancy and lactation. The patients treated with antithyroid belonged to relatively younger age, and also milder in symptoms and thyroid function tests. The remission rate of antithyroid therapy group was 97.8% within 16 months. Among them the early remission rate occured within 4 months was found to be 21.7%. The combined therapy group, having prescribed more severe cases, showed the remission rate to be 75% within 16 months. The remission rate of $^{131}I$ therapy group revealed 90.9% within 16 months. Among them the early remission rate taking place within 4 months disclosed 16.7%. The side effects of antithyroid drug, propylthiouracil, were noted as follows: itching (2.7%) skin rashes (1.3%), and adverse enlargement of goiter (10.7%). The side effects $^{131}I$ therapy were transient hypothyroidism(3.9%) permanent hypothyroidism (7.8%) and itching (2.0%).

• The Korean Journal of Nuclear Medicine
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• v.29 no.3
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• pp.319-327
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• 1995

$^{131}I$-metaiodobenzylguanidine(MIBG) has been used for the diagnosis and treatment of neural crest tumors. We report our experience with this agent in 8 patients[1 multiple endocrine neoplasia(MEN) type IIb; 2 malignant pheochromocytoma; 5 medullary thyroid carcinoma(MTC)]. The therapeutic procedure consisted of 30-200 mCi of $^{131}I-MIBG$ administered by slow I.V. infusion, given at 3-6 months intervals. Commutative activity ranged from 150 mCi to 410 mCi, in 1 to 4 courses. $^{131}I-MIBG$ therapy resulted in significant disease free interval in 1 malignant pheochromocytoma(no measurable lesion) after surgery; complete hormonal and tumoral response in 2 MTC(1 MEN IIb): stable disease in 1 recurred pheochromocytoma(MEN IIb): stable disease but symptomatic improvement in 1 MTC, progressive disease in 1 malignant pheochromocytoma and 2 MTC. The patients who showed progression appeared to have large inoperable tumors or postoperative remnant tumors.

• 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.

• The Korean Journal of Nuclear Medicine
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• v.30 no.1
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• pp.77-85
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• 1996

Radioiodine($^{131}I$) has been used for the treatment of Graves' hyperthyroidism since the late 1940's and is now generally regarded as the treatment of choice for Graves' hyperthyroidism who does not remit following a course of antithyroid drugs. But for the dose given, several different protocols have been described by different centers, each attempting to reduce the incidence of long-term hypothyroidism while maintaining an acceptable rate control of Graves' hyperthyroidism. Our goals were to evaluate effective half-life and predict absorbed dose in Graves' hyperthyroidism patients, therefore, to calculate and readminister radioiodine activity needed to achieve aimed radiation dose. Our data showed that the mean effective $^{131}I$ half-life for Graves' disease is 5.3 days(S.D=0.88) and mean biologic half-life is 21 days, range 9.5-67.2 days. The mean admininistered activity and the mean values of absorbed doses were 532 MBq(S.D.=254), 112 Gy (S.D.=50.9), respectively. The mean activity needed to achieve aimed radiation dose were 51MBq and marked differences of $^{131}I$ thyroidal uptake between tracer and therapy ocurred in our study. We are sure that the dose calculation method that uses 5 days thyroidal $^{131}I$ uptake measurements after tracer and therapy dose, provides sufficient data about the effective half-life and absorbed dose of $^{131}I$ in the thyroid and predict the effectiveness of $^{131}I$ treatment in Graves' hyperthyroidism.

• 대한방사선방어학회:학술대회논문집
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• 2011.04a
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• pp.76-77
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• 2011

• 대한방사선방어학회:학술대회논문집
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• 2010.04a
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• pp.108-109
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• 2010

• Nuclear Medicine and Molecular Imaging
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• v.43 no.6
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• pp.582-587
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• 2009

A 59-year-old woman who was diagnosed with malignant pheochromocytoma underwent $^{18}F$-fluorodeoxyglucose positron emission tomography/computed tomography ($^{18}F$-FDG PET/CT). She had undergone left adrenalectomy for pheochromocytoma 4 years previously. Recent multiple metastatic pulmonary nodules were noted on the chest X-ray. After treatment with $^{131}I$-metaiodobenzylguanidine ($^{131}I$-MIBG) with 7.4 GBq, post-therapy $^{131}I$-MIBG scintigraphy depicted multiple distant metastases including lung, liver, abdominal para-aortic and mesenteric lymph nodes. $^{18}F$-FDG PET/CT also depicted multiple metastases in lung, liver, and abdominal para-aortic lymph nodes, but some lesions were not shown. In this case, $^{131}I$-MIBG scintigraphy found additional lesions in metastatic malignant pheochromocytoma.

• 대한핵의학회:학술대회논문집
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• 1973.11a
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• pp.51.1-51.1
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• 1973

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.57-61
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• 2014

Purpose Iodine (I-131) is one of the most widely used radioactive isotopes for therapeutic in the field of nuclear medicine. Therapeutic I-131 capsule is made out of lead to shield high energy radiation. Accurate dosimetry is necessarily required to perform safe and effective work for relative workers. The Monte Carlo method is known as a method to predict the absorbed dose distribution most accurately in radiation therapy and many researchers constantly attempt to apply this method to the dose calculation of radiotherapy recently. This paper aims to calculate distance dependent and activity dependent therapeutic I-131 capsule using GEANT4. Materials and Methods Therapeutic capsules was implemented on the basis of the design drawings. The simulated dose was determined by generating of gamma rays of energy to more than 364 keV. The simulated dose from the capsule at the distance of 10 cm and 100 cm was measured and calculated in the model of water phantom. The simulated dose were separately calculated for each position of each detector. Results According to the domestic regulation on radiation safety, the dose at 10 cm and 100 cm away from the surface of therapeutic I-131 capsule should not exceed 2.0 mSv/h and 0.02 mSv/h, respectively. The simulated doses turned out to be less than the limit, satisfying the domestic regulation. Conclusion These simulation results may serve as useful data in the prediction of hands dose absorbed by I-131 capsule handling. GEANT4 is considered that it will be effectively used in order to check the radiation dose.