• Journal of Radiation Industry
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• v.12 no.4
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• pp.277-285
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• 2018

Patients administered radioisotope for medical purposes are regulated by each country to quarantine them until their body's radioactivity contents decrease below release criteria. To predict the quarantine period and provide it to medical staffs and patients, it is necessary to approach the assessment of the exposure dose of persons due to patients in a realistic manner. For this purpose, a whole-body effective half-life should be applied to the dose assessment equation instead of the physical half-life. In this study, we constructed a bio-kinetic model for each nuclear species based on the ICRP publication to obtain a whole-body effective half-life of 10 unsealed gamma-ray emitting nuclei from the notification of Nuclear Safety and Security Commission, and calculated the effective half-life mathematically by simulating the distribution of the radioisotope administered in the whole body as well as each organ scale. The whole-body effective half-life of $^{198}Au$, $^{67}Ga$, $^{123}I$, $^{111}In$, $^{186}Re$, $^{99m}Tc$, and $^{201}TI$ were 1,93, 2.57, 0.295, 2.805, 1.561, 0.245, and 2.397 days respectively. However, it was found to be undesirable to offer a single value of the effective half-life of $^{125}I$, $^{131}I$, and $^{169}Yb$ because the changes in the effective half-life show no linearity. A bio-kinetic model created for the internal exposure assessment has been shown to be possible to calculate the effective half-life of radioisotopes administered in the patient's body, but subsequent studies of radiolabeled compounds are required as well.

• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.533-538
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• 2021

^99mTcO₄^- is used to measure thyroid uptake. When measuring background radioactivity of the thigh, the distance between the detector and the thigh was 20 cm at a position 10 cm above the knee from the knee to the pelvis. At 25 cm, many hospitals are measuring at different distances. The purpose of this study was to study the difference in effectiveness in obtaining the thyroid uptake rate by quantitatively analyzing the uptake rate measurement at two distances. As a result, the average thyroid uptake rate measured at 20 cm in the thigh of 50 patients was 3.532±4.312%, and the average thyroid uptake rate measured at 25 cm was 3.680±4.304%. As a result of the thyroid uptake rate test result, the femoral background radioactivity value measured at a distance of 20 cm was relatively higher than the background radioactivity value measured at a distance of 25 cm, and as a result, the thyroid uptake rate was 0.148% lower.

• Journal of radiological science and technology
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• v.45 no.4
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• pp.331-339
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• 2022

The purpose of this study was to evaluate maternal organ and fetal doses by week of pregnancy for pregnant women nuclear medicine practitioners in the nuclear medicine field. In addition, we intend to present basic data for the management of exposure doses of female nuclear medicine practitioners. In this study, phantoms of childbearing women, 3, 6, 9 months pregnant women were simulated using MCNPX(Monte Carlo N-Particle Extended) among the Monte Carlo methods. First, volume source was constructed based on 10 cm of the anterior part of the lower abdomen of the phantom, and the organ and fetal doses were evaluated for each week of the pregnant woman according to the type of radioactive isotope. Second, the organ and fetal dose of pregnant women were evaluated by increasing the distance between the source and the abdominal surface by 50 and 100 cm. As a result, ¹⁸F sources showed high organ and fetal doses in pregnant women 0 to 3 months, and the dose distribution gradually decreased in 6 to 9 months pregnant women. The distribution of organ and fetal doses for ⁹⁹mTc and ¹²³I sources showed the same tendency as that of ¹⁸F, and the overall absorbed dose distribution was relatively lower than that of ¹⁸F. Through this study, it is considered that workers in the early stages of pregnancy within 3 months will need appropriate management to minimize occupational exposure dose.

• Childhood Kidney Diseases
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• v.26 no.1
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• pp.52-57
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• 2022

Purpose: To determine predictive factors for detecting renal parenchymal damages (RPDs) in infants with recurrent febrile urinary tract infection (fUTI). Methods: From January 2015 to December 2021, 102 infants with recurrent fUTI and who underwent ^99mTc-dimercaptosuccinic acid (DMSA) renal scan in our hospital were included in this study. Controls included infants with normal DMSA results performed 3 months apart from the 2nd episode of fUTI. DMSA-positive group included infants with positive DMSA results performed 3 months apart from the 2nd episode of fUTI or at the 3rd episode of fUTI. The recurrence rate, causative bacteria, renal size discrepancy of both kidneys, and laboratory findings including C-reactive protein (CRP) and spot urine sodium-to-potassium ratio (uNa/K) were compared between both groups. Results: Only 3.8% of 79 infants with a 2nd episode of fUTI showed positive DMSA results. fUTI recurred more frequently within 12 months of follow-up in the DMSA-positive group than in the control group (69% vs. 13%, P<0.001). CRP values were significantly higher in the DMSA-positive group than in the control group (7.3 mg/dL vs. 3.7 mg/dL, P<0.001). Spot uNa/K were significantly lower in the DMSA-positive group than in the control group (0.6 vs. 1.1, P<0.001). Conclusions: Congenital renal scar and RPDs on the DMSA scan were more frequently found in infants with recurrent fUTI than those in the control group. High CRP values and low spot uNa/K in acute infections were helpful in predicting the presence of RPD in infants with recurrent fUTI.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.8 no.1
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• pp.45-49
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• 2022

With the development of monoclonal antibodies, therapeutic or diagnostic radioisotope has been successfully delivered at tumor sites with high selectivity for antigens. Different approaches have been applied to improve the tumor-to-normal ratio by considering the in vivo stability of radioimmunoconjugates as a prerequisite. Various stable and inert antibody radiolabeling techniques for radioimmunoconjugate preparation have been extensively evaluated to enhance in vivo stability. Antibody radiolabeling techniques should be rapid and easy; they should not disrupt the immunoreactivity and in vivo behavior of antibodies, which are coupled with a bifunctional chelator (BFC) to stably coordinate with a radiometal. For the design of BFCs, radiometal coordination properties must be considered. However, various diagnostic radionuclides, such as ⁸⁹Zr, ⁶⁴Cu, ⁶⁸Ga, ¹¹¹ln, and ^99mTc, or therapeutic radionuclides, such as ¹⁷⁷Lu, ⁶⁷Cu, ⁹⁰Y, and ²²⁵Ac, have been increasingly used for antibody radiolabeling. In addition to useful radionuclides, ⁶⁴Cu and ¹⁷⁷Lu with the most accessible or the highest production rates in many countries should be considered. In this review, we mainly discussed antibody radiolabeling techniques and conditions that involve ⁶⁴Cu and ¹⁷⁷Lu radiometals.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.9 no.1
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• pp.23-33
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• 2023

Prostate cancer ranks as the world's second most frequently diagnosed cancer among men, and is responsible for the fifth highest number of cancer-related deaths in this population. The development of effective diagnostic and therapeutic approaches for prostate cancer remains a major challenge in the field of oncology. Over the past few years, the prostate-specific membrane antigen (PSMA) has raised as a hopeful tracer for the diagnosis and treatment of prostate cancer.Various radioisotopes, such as ¹³¹I, ^99mTc, ⁶⁸Ga, and ¹⁷⁷Lu, have been used to label PSMA analogues, with varying degrees of success. Among these, ⁶⁸Ga-PSMA-11 and ¹⁷⁷Lu-PSMA-617 have emerged as the most promising radioligands for clinical use. Recently, researchers have been exploring the use of other radioisotopes, such as ²¹¹At, ⁸⁹Zr, ^64/67Cu, and ^203/212Pb, for the labeling of PSMA-targeted radioligands. These radioisotopes have unique properties that may offer advantages over existing radioligands, such as longer half-lives, higher specific activities, and different emission profiles. Efforts are currently underway to develop these radiopharmaceuticals and make them more widely available for clinical use. These exciting developments highlight the potential of PSMA-targeted radioligands for the diagnosis and treatment of prostate cancer, and provided significant implications for the management of this disease in the future. The current study aims to provide a comprehensive summary of the latest research and clinical applications of radiolabeled PSMA inhibitors for diagnoses and therapy of prostate cancer, emphasizing the exciting developments in the field and their potential impact on clinical practice.

• Korean Journal of Head & Neck Oncology
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• v.39 no.1
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• pp.53-57
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• 2023

In general, the anatomical location and number of parathyroid glands are well known, but they are often found in a variety of locations, making it difficult to find parathyroid glands during surgery. Besides Intra-thyroidal parathyroid adenoma is extremely rare case, and it is harder to identify in surgery. We encountered a 51-year-old patient with a thyroid nodule. The results of the additional blood test and the Tc-99m MIBI were combined to determine that the left lower lobe parathyroid adenoma was highly likely. This patient was treated with left thyroid lobectomy with parathyroid identification using Near-infrared (NIR) imaging. Afterwards, the biopsy confirmed that it was a parathyroid adenoma, and has since been monitored through outpatient observation without any problem. We present this rare case with a review of related literatures.

• Korean Journal of Radiology
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• v.24 no.6
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• pp.574-589
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• 2023

Radiopharmaceuticals targeting prostate-specific membrane antigens (PSMA) are essential for the diagnosis, evaluation, and treatment of prostate cancer (PCa), particularly metastatic castration-resistant PCa, for which conventional treatment is ineffective. These molecular probes include [⁶⁸Ga]PSMA, [¹⁸F]PSMA, [Al¹⁸F]PSMA, [^99mTc]PSMA, and [⁸⁹Zr]PSMA, which are widely used for diagnosis, and [¹⁷⁷Lu]PSMA and [²²⁵Ac]PSMA, which are used for treatment. There are also new types of radiopharmaceuticals. Due to the differentiation and heterogeneity of tumor cells, a subtype of PCa with an extremely poor prognosis, referred to as neuroendocrine prostate cancer (NEPC), has emerged, and its diagnosis and treatment present great challenges. To improve the detection rate of NEPC and prolong patient survival, many researchers have investigated the use of relevant radiopharmaceuticals as targeted molecular probes for the detection and treatment of NEPC lesions, including DOTA-TOC and DOTA-TATE for somatostatin receptors, 4A06 for CUB domain-containing protein 1, and FDG. This review focused on the specific molecular targets and various radionuclides that have been developed for PCa in recent years, including those mentioned above and several others, and aimed to provide valuable up-to-date information and research ideas for future studies.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.33-37
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• 2010

Purpose: In the early stage of using PET/CT, it was used to damper revision but recently shows that CT with MDCT is commonly used and works well for an anatomical diagnosis. This hospital makes the accuracy and convenience more higher in the diagnosis and evaluate of coronary heart disease through concurrently running myocardial perfusion SPECT examination, myocardial PET examination with FDG, and CT coronary artery CT angiography(coronary CTA) used PET/CT with 64-slice. This report shows protocol and image based on results from about 400 coronary heart disease examinations since having 64 channels PET/CT in July 2007. Materials and Methods: An Equipment for this examination is 64-slice CT and Discovery VCT (DVCT) that is consisted of PET with BGO ($Bi_4Ge_3O_{12}$) scintillation crystal by GE health care. First myocardial perfusion SPECT with pharmacologic stress test to reduce waiting time of a patient and get a quick diagnosis and evaluation, and right after it, myocardial FDG PET examination and coronary CTA run without a break. One-stop evaluation protocol of ischemic heart disease is as follows. 1)Myocardial perfusion SPECT with pharmacologic stress: A patient is injected with $^{99m}Tc$-MIBI 10 mCi and does not have any fatty food for myocardial PET examination and drink natural water with ursodeoxcholic acid 100 mg and we get SPECT image in an hour. 2)Myocardial FDG PET: To reduce blood fatty content and to increase uptake of FDG, we used creative oral glucose load using insulin and Acipimox to according to blood acid content. A patient is injected with $^{18}F$-FDG 5 mCi for reduction of his radiation exposure and we get a gated image an hour later and get delay image when we need. 3) Coronary CTA: The most important point is to control heart rate and to get cooperation of patient's breath. In order to reduce a heart rate of him or her below 65 beats, let him or her take beta blocker 50 mg ~ 200 mg after a consultation with a doctor about it and have breath-practices then have the examination. Right before the examination, we spray isosorbide dinitrate 3 to 5 times to lower tension of bessel wall and to extension a blood wall of a patient. It makes to get better the shape of an anatomy. At filming, a patient is injected CT contrast with high pressure and have enough practices before the examination in order to have no problem. For reduction of his radiation exposure, we have to do ECG-triggered X-ray tube modulation exposure. Results: We evaluate coronary artery stenosis through coronary CTA and study correlation (culprit vessel check) of a decline between stenosis and perfusion from the myocardial perfusion SPECT with pharmacologic stress, coronary CTA, and can check viability of infarction or hibernating myocardium by FDG PET. Conclusion: The examination makes us to set up a direction of remedy (drug treatment, PCI, CABG) because we can estimate of effect from remedy, lesion site and severity. In addition, we have an advantage that it takes just 3 hours and one-stop in that all of process of examinations run in succession and at the same time. Therefore it shows that the method is useful in one stop evaluation of ischemic heart disease.

• The Korean Journal of Nuclear Medicine Technology
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• v.25 no.2
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• pp.15-24
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• 2021

Purpose SPECT/CT was noted for its excellent correction method and qualitative functions based on fusion images in the early stages of dissemination, and interest in and utilization of quantitative functions has been increasing with the recent introduction of companion diagnostic therapy(Theranostics). Unlike PET/CT, various conditions like the type of collimator and detector rotation are a challenging factor for image acquisition and reconstruction methods at absolute quantification of SPECT/CT. Therefore, in this study, We want to find out the effect on the radioactivity concentration estimate by the increase or decrease of the total acquisition time according to the number of projections and the acquisition time per projection among SPECT/CT imaging conditions. Materials and Methods After filling the 9,293 ml cylindrical phantom with sterile water and diluting 99mTc 91.76 MBq, the standard image was taken with a total acquisition time of 600 sec (10 sec/frame × 120 frames, matrix size 128 × 128) and also volume sensitivity and the calibration factor was verified. Based on the standard image, the comparative images were obtained by increasing or decreasing the total acquisition time. namely 60 (-90%), 150 (-75%), 300 (-50%), 450 (-25%), 900 (+50%), and 1200 (+100%) sec. For each image detail, the acquisition time(sec/frame) per projection was set to 1.0, 2.5, 5.0, 7.5, 15.0 and 20.0 sec (fixed number of projections: 120 frame) and the number of projection images was set to 12, 30, 60, 90, 180 and 240 frames(fixed time per projection:10 sec). Based on the coefficients measured through the volume of interest in each acquired image, the percentage of variation about the contrast to noise ratio (CNR) was determined as a qualitative assessment, and the quantitative assessment was conducted through the percentage of variation of the radioactivity concentration estimate. At this time, the relationship between the radioactivity concentration estimate (cps/ml) and the actual radioactivity concentration (Bq/ml) was compared and analyzed using the recovery coefficient (RC_Recovery Coefficients) as an indicator. Results The results [CNR, radioactivity Concentration, RC] by the change in the number of projections for each increase or decrease rate (-90%, -75%, -50%, -25%, +50%, +100%) of total acquisition time are as follows. [-89.5%, +3.90%, 1.04] at -90%, [-77.9%, +2.71%, 1.03] at -75%, [-55.6%, +1.85%, 1.02] at -50%, [-33.6%, +1.37%, 1.01] at -25%, [-33.7%, +0.71%, 1.01] at +50%, [+93.2%, +0.32%, 1.00] at +100%. and also The results [CNR, radioactivity Concentration, RC] by the acquisition time change for each increase or decrease rate (-90%, -75%, -50%, -25%, +50%, +100%) of total acquisition time are as follows. [-89.3%, -3.55%, 0.96] at - 90%, [-73.4%, -0.17%, 1.00] at -75%, [-49.6%, -0.34%, 1.00] at -50%, [-24.9%, 0.03%, 1.00] at -25%, [+49.3%, -0.04%, 1.00] at +50%, [+99.0%, +0.11%, 1.00] at +100%. Conclusion In SPECT/CT, the total coefficient obtained according to the increase or decrease of the total acquisition time and the resulting image quality (CNR) showed a pattern that changed proportionally. On the other hand, quantitative evaluations through absolute quantification showed a change of less than 5% (-3.55 to +3.90%) under all experimental conditions, maintaining quantitative accuracy (RC 0.96 to 1.04). Considering the reduction of the total acquisition time rather than the increasing of the image acquiring time, The reduction in total acquisition time is applicable to quantitative analysis without significant loss and is judged to be clinically effective. This study shows that when increasing or decreasing of total acquisition time, changes in acquisition time per projection have fewer fluctuations that occur in qualitative and quantitative condition changes than the change in the number of projections under the same scanning time conditions.