• The Korean Journal of Nuclear Medicine
• /
• v.35 no.3
• /
• pp.117-124
• /
• 2001

Serum thyroglobulin measurement and I-131 whole-body scintigraphy (WBS) are well-established methods for the detection of recurrence in the follow-up of patients with thyroid carcinoma. However, inconsistent results are observed frequently, and these two methods are not always able to detect recurrence. In some patients, serum thyroglobulin level is elevated but the WBS is negative, because the recurrent tumor is too small and below the sensitivity of the diagnostic scan, or there is a dissociation between thyroglobulin synthesis and the iodine frapping mechanism. In such cases, various nuclear imaging methods including Tl-201 Tc-99m-sestamibi, and F-18-FDG PET can be used besides anatomical imaging methods. Among them, FDG PET localizes recurrent lesions in WBS-negative thyroid carcinoma with high accuracy. Several studies have suggested that empirical high-dose I-131 therapy resulted in a high rate of visualization in post-therapy scans with evidence of subsequent improvement. An important question is when to operate on patients with recurrent tumor. We believe that surgical removal is the best means of treatment for patients with localized persistent tumor, despite the high-dose I-131 therapy. with tumor in thyroid remnant, and with isolated recurrence in the lymph node, lung or bone. In addition, we recommend palliative resection of locally unresectable mass with subsequent treatment with high-dose I-131 therapy. Before I-131 therapy, the evaluation of sodium-iodide symporter expression in thyroid carcinoma can predict iodine uptake. Retinoic acid is known to induce redifferentiation, and to enhance I-131 uptake in thyroid carcinoma. Retinoic acid therapy may represent an alternative approach before high-dose I-131 therapy.

• Korean Journal of Head & Neck Oncology
• /
• v.14 no.2
• /
• pp.214-219
• /
• 1998

Objectives: To assess the effectiveness of the low-dose(30mCi) I-131 ablation therapy for remnant thyroid tissue following total thyroidectomy for differentiated thyroid cancer. Methods: Between March 1995 and December 1997, forty-eight patients were given ablative doses(30mCi) of I-131 after total thyroidectomy for differentiated thyroid cancer in the presence of I-131 uptake in remnant thyroid tissue. Effective ablation of remnant thyroid tissue was determined by following I-131 whole body scan. if remnant thyroid tissue remained, we repeated the same management at 6 months interval. Results: Thirty-eight(79.1%) patients had papillary, 8(16.7%) follicular, 1(2.1%) medullary and 1(2.1%) Hurthle cell type cancer. Forty-eight patients underwent total thyroidectomy, among those central neck dissection was performed in 35 cases, and modified radical neck dissection in 14 cases. Postoperative complication developed in 8 cases, which included 4 cases of transient hypoparathyroidism, 1 case of permanent hypoparathyroidism, 2 cases of transient recurrent laryngeal nerve palsy, and 1 case of wound hematoma. There were significant remnant thyroid tissue in 46 cases(95.8%) of patients after total thyroidectomy, which could be ablated by low dose(30mCi) I-131. There were no statistical difference between operative procedures and number of treatment of I-131. Conclusions: These results suggested that repeated low-dose(30mCi) I-131 therapy would be needed, therefore, high -dose I-131 therapy could be considered as ablation therapy for the remnant thyroid tissue after total thyroidectomy for differentiated thyroid cancer.

• Journal of the Korean Society of Radiology
• /
• v.7 no.3
• /
• pp.251-257
• /
• 2013

Spatial dose rates of high dose $^{131}I$ therapy patients were Measured Three dimensional (X, Y, Z) distributions. I have constructed geometrical an aluminum support structure for spatial dose meters placed in 5 different heights, 8 different azimuthal angles, 6 different time interval and distance 100 cm from High dose$^{131}I$ therapy patients. when the height of vertical plane Spatial dose distribution is 100 cm, the Spatial dose rates is max and the error range is low. the vertical plane Spatial dose rates was found to be 71.85 ${\mu}Sv/h$ on the average at a distance of 100 cm, height 100 cm, from the patients 24 hours after $^{131}I$ oral administration. I divided 12 patients into two groups. I have analysed group A (drinking 5 L water) and group B (drinking 3 L water) in order to measure decrease spatial dose rates. I have found the spatial distributions of patient dose rates is $44.9{\pm}7.2$ ${\mu}Sv/h$ in group A and $100.3{\pm}8.1$ ${\mu}Sv/h$ in group B by 24 after $^{131}I$ oral administration. the reduction factor was found to be approximately 54 % through drinking 5 L water during 24 hours.

• The Korean Journal of Nuclear Medicine
• /
• v.37 no.2
• /
• pp.120-127
• /
• 2003

Purpose: To evaluate diagnostic sensitivity of nuclear imaging in the detection of residual thyroid tissue and metastatic lesion, we have compared neck scintigrams with Tc-99m pertechnetate (Tc-99m scan) and high dose I-131 iodide (I-131 scan) in patients with differentiated thyroid cancer. Subjects and Methods: One hundred thirty-five thyroidectomized patients for differentiated thyroid cancer were enrolled in this study. Twenty-three had a previous history of radioiodine therapy. Planar and pin-hole images of anterior neck with Tc-99m were acquired at 20 minutes after injection, followed by I-131 scan three days after high-dose radioiodine therapy within 7 days interval. Patients were asked to discontinue thyroid hormone replacement more than 4 weeks. Results: All subjects were in hypothyroid state. Seventy out of 135 patients (51.9%) showed concordant findings between Tc-99m and I-131 scans. I-131 scan showed higher number of uptake foci in all of 65 patients showing discordant finding. Tc-99m scan showed no thyroid bed uptake in 34 patients, whereas 23 of them (67.6%) showed bed uptake in I-131 scan. Tc-99m scan did not show any uptake in thyroid bed in 11 of 112 patients without previous history of radioiodine therapy, but 9 of them showed bed uptake in I-131 scan. Tc-99m scan showed no bed uptake in all of the 23 patients with previous history of radioiodine therapy, in contrast 14 of them (60.9%) showed bed uptake in I-131 scan. Conclusion: These results suggest that Tc-99m scan has poor detectability for residual thyroid tissue or metastatic lesion in thyroidectomized differentiated thyroid cancer patients, compared to high dose I-131 therapy scan. Tc-99m scan could not detect any remnant tissue or metastatic lesion in patients with previous history of radioiodine treatment, especially.

• Journal of the Korean Society of Radiology
• /
• v.13 no.4
• /
• pp.653-659
• /
• 2019

The purpose of this study is to measure the (air dose rate of radiation dose) the discharged patient who was administrated high dose $^{131}I$ treatment, and to predict exposure radiation dose in public person. The dosimetric evaluation was performed according to the distance and angle using three copper rings in 30 patients who were treated with over 200mCi high dose Iodine therapy. The two observer were measured using a GM surverymeter with 8 point azimuth angle and three difference distance 50, 100, 150cm for precise radion dose measurement. We set up three predictive simulations to calculate the exposure dose based on this data. The most highest radiation dose rate was showed measuring angle $0^{\circ}$ at the height of 1m. The each distance average dose rate was used the azimuth angle average value of radiation dose rate. The maximum values of the external radiation dose rate depending on the distance were $214{\pm}16.5$, $59{\pm}9.1$ and $38{\pm}5.8{\mu}Sv/h$ at 50, 100, 150cm, respectively. If high dose Iodine treatment patient moves 5 hours using public transportation, an unspecified person in a side seat at 50cm is exposed 1.14 mSv radiation dose. A person who cares for 4days at a distance of 1 meter from a patient wearing a urine bag receives a maximum radiation dose of 6.5mSv. The maximum dose of radiation that a guardian can receive is 1.08mSv at a distance of 1.5m for 7days. The annual radiation dose limit is exceeded in a short time when applied the our developed radiation dose predictive modeling on the general public person who was around the patients with Iodine therapy. This study can be helpful in suggesting a reasonable guideline of the general public person protection system after discharge of high dose Iodine administered patients.

• The Korean Journal of Nuclear Medicine
• /
• v.35 no.2
• /
• pp.83-88
• /
• 2001

Purpose: The purpose of this study was to ascertain whether radiation adaptive response could be induced by high dose I-131 therapy in patients with differentiated thyroid cancer. Materials and Methods: Lymphocytes from 21 patients (7 males, 14 females, mean age $55{\pm}12$ years) were collected before and after administration of 5,550 MBq (150 mCi) I-131. They were exposed to a challenge dose of 1 Gy gamma rays using a Cs-137 cell irradiator. The number of ring-form (R) and dicentric (D) chromosomes was counted under the light microscope, and used to calculate the frequency of chromosomal aberration. Ydr, which was defined as the sum of R and D divided by the total number of counted lymphocytes. Results: Ydr in patients before I-131 therapy ($0.09{\pm}0.01$) was not different from that of controls ($0.08{\pm}0.01$). Ydr was significantly increased to $0.13{\pm}0.02$ (p<0.0001) after I-131 therapy. Increase of Ydr after the challenge irradiation of 1 Gy was significantly lower in patients after I-131 therapy than before I-131 therapy ($0.17{\pm}0.03\;vs\;0.21{\pm}0.02$, p<0.0001). Cycloheximide (CHM), an inhibitor of protein synthesis, abolished this effect. Ydr after CHM ($0.20{\pm}0.01$) was significantly higher than Ydr after I-131 therapy ($0.17{\pm}0.03$, p<0.0001), but was not different from Ydr before I-131 therapy ($0.21{\pm}0.02$).Conclusion: High dose I-131 therapy induces an adaptive response in peripheral lymphocytes of patients with well-differentiated thyroid cancer, which is associated with protein synthesis.

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

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

• Journal of radiological science and technology
• /
• v.39 no.4
• /
• pp.565-570
• /
• 2016

Radioactive iodine($^{131}I$) treatment reduces recurrence and increases survival in patients with differentiated thyroid cancer. However, it is important in terms of radiation safety management to measure the radiation dose rate generated from the patient because the radiation emitted from the patient may cause the exposure. Research methods, it measured radiation dose-rate according to the elapsed time from 1 m from the upper abdomen of the patient by intake of radioactive iodine. Directly comparing the changes over time, high dose rate sensitivity and efficiency is statistically significant, and higher chamber than GM counter(p<0.05). Low dose rate sensitivity and efficiency in the chamber had lower levels than gm counter, but not statistically significant(p>0.05). In this study confirmed the characteristics of calibrated ionization chamber and GM counter according to the radiation intensity during high-dose radioactive iodine therapy by measuring the accurate and rapid radiation dose rate to the patient explains, discharged patients will be reduced to worry about radiation hazard of family and others person.

• Journal of radiological science and technology
• /
• v.30 no.4
• /
• pp.435-442
• /
• 2007

The number of thyroid diseases treated with radioiodine(I-131) is increasing steadily. The sharp increase in patients who require high dose radioiodine therapy greatly increased the need for new therapy rooms. Accordingly, interest in radiation exposure is rising as well, and is a major psychological stress factor for the patient and those who come in close contact with the patient. This study aimed to minimize the radiation exposure on discharge. Based on various previous reports, the decision for discharge should be individualized depending on many factors related to the patient's living or working environment. Educating patients repeatedly on the importance of sufficient oral hydration, while the adequate amount was relative to the patient's individual condition, greatly lowered the detected radiation measurement within the same admission period. In some cases, the period of admission could be abbreviated.