• Journal of Radiation Industry
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• v.11 no.1
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• pp.13-18
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• 2017

Recently, the number of PET cyclotrons has increased in Korea. A cyclotron mainly produces $^{18}F$, which is used for the production of [$^{18}F$]FDG, a cancer diagnostic radiopharmaceutical. For radiation protection, the discharge control standard under the Nuclear Safety Act limits the radioactive concentration of $^{18}F$ in the exhaust discharged from a nuclear power utilization facility to below $2,000Bq\;m^{-3}$. However, the radioactive concentration of $^{18}F$ discharged during [$^{18}F$]FDG production at the cyclotron facility at Chosun University is maintained at about $1,500Bq\;m^{-3}$ on average, which is 75% of the concentration limit of the discharge control standard, and temporarily exceeds the standard as per the real-time monitoring results. This study evaluated the performance of the exhaust filter unit of the cyclotron facility at Chosun University by assessing the concentration of $^{18}F$ in the exhaust, and an experiment was conducted on the discharge reduction, where $^{18}F$ is discharged without reacting with the FDG precursors during [$^{18}F$]FDG synthesis and is immediately captured by the [$^{18}F$]FDG automatic synthesis unit. Based on the performance evaluation results of the exhaust filter at the cyclotron facility of Chosun University, the measured capture efficiency before and after the filter was found to be 92%. Furthermore, the results of the discharge reduction experiment, where the exhaust $^{18}F$ was immediately captured by the [$^{18}F$]FDG synthesizer, showed a very satisfactory 94.3% reduction in the concentration of discharge compared to the existing discharge concentration.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.5
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• pp.410-413
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• 2008

A 56 years old woman referred to our hospital with dysphagia and epigastric soreness. Gastroendoscopy revealed huge submucosal tumor with ulceration extending from distal esophagus to lesser curvature of stomach. Subsequent computed tomography(CT) demonstrated soft tissue mass encircling distal esophagus, and 18F-FDG PET/CT demonstrated intense $^{18}F-FDG$ accumulation in it. Finally this case was diagnosed as esophageal leiomyoma based on pathologic evaluation of the surgical specimen.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3569-3573
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• 2016

Purpose: The aim of this study was to compare C-11 choline and F-18 FDG PET/CT, gadoxetic-enhanced 3-T MRI and contrast-enhanced CT for diagnosis of hepatocellular carcinoma (HCC). Materials and Methods: Twelve chronic hepatitis B patients suspected of having HCC by abdominal ultrasonography received all diagnostic modalities performed within a one-week timeslot. PET/CT results were analyzed visually by two independent nuclear medicine physicians and quantitatively by tumor to background ratio (T/B). Nine patients then had histopathological confirmation. Results: Six patients had well differentiated HCC, while two and one patient(s) were noted with moderately and poorly differentiated HCC, respectively. All were detected by both CT and MRI with an average tumor size of $5.7{\pm}3.8cm$. Five patients had positive C-11 choline and F-18 FDG uptake. Of the remaining four patients, three with well differentiated HCC showed negative F-FDG uptake (one of which showed negative results by both tracers) and one patient with moderately differentiated HCC demonstrated no C-11 choline uptake despite intense F-18 FDG avidity. The overall HCC detection rates with C-11 choline and F-18 FDG were 78% and 67%, respectively, while the sensitivity of F-18 FDG for non-well differentiated HCC was 100%, compared with 83% of C-11 choline. The average T/B of C-11 choline in well-differentiated HCC patients was higher than in moderately and poorly differentiated cases (p=0.5) and vice versa with statistical significance for T/B of F-18 FDG (p = 0.02). Conclusions: Our results suggested better detection rate in C-11 choline for well differentiated HCC than F-18 FDG PET. However, the overall detection rate of PET/CT with both tracers could not compare with contrast-enhanced CT and MRI.

• Journal of Radiation Industry
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• v.10 no.1
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• pp.37-41
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• 2016

The recent prevalence of PET examinations in Korea has led to an increase in the number of cyclotrons. The medical isotope $^{18}F$ produced in most cyclotron facilities currently operating in Korea is emitted into the environment during the production of [$^{18}F$]FDG, a cancerdiagnosis reagent. The amount of [$^{18}F$]FDG synthesized determines the radioactive concentration of $^{18}F$ in the exhaust. At some facilities, this amount temporarily exceeds the emission limit. In this study, we evaluated the $^{18}F$ radioactivity concentration in the exhaust from the cyclotron facility at Chosun University. The $^{18}F$ radioactivity concentration was measured using an air sampler and a HPGe semiconductor detector. The measurements showed that the radioactive concentration of $^{18}F$ in the exhaust at the cyclotron facility at Chosun University was the highest during [$^{18}F$]FDG synthesis but remained under the legal limit of $2,000Bq\;m^{-3}$.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.6
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• pp.543-556
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• 2009

Purpose: We studied the patterns of FDG uptake of primary papillary thyroid microcarcinoma (PTMCa) lesions and benign thyroid nodules in dual time point $^{18}F$-FDG PET/CT imaging. Materials and Methods: Consecutive 134 patients (154 lesions) with PTMCa and 49 patients (61 nodules) with benign thyroid nodules equal to or less than 1.0 cm who underwent dual time point $^{18}F$-FDG PET/CT study before surgery were enrolled. We calculated the maximum standardized uptake value of PTMCa and benign nodules in both time points, and percent change of SUVmax (${\Delta}%SUVmax$) and lesion to background ratio of SUVmax (${\Delta}L:B$% ratio) between both time points. The mean time interval between scans was $23.4{\pm}4.4$ minutes (thyroid to thyroid interval: $10.7{\pm}4.4$ minutes). Results: The mean of SUVmax of PTMCa was increased from $4.9{\pm}4.3$ to $5.3{\pm}4.7$ (p<0.001) and ${\Delta}%SUVmax$ was $12.3{\pm}23.6%$. But, the mean of SUVmax of benign nodules was no definite change ($2.1{\pm}1.0$ to $2.1{\pm}1.3$, p=0.686) and ${\Delta}%SUVmax$ was $-0.3{\pm}20.5%$. Of the 154 PTMCa, 100 nodules (64.9%) showed an increase in SUVmax over time, while 19 (31.1%) of the 61 benign thyroid nodules showed an increase (p<0.001). The dual time point $^{18}F$-FDG PET/CT found more PTMCa in visual assessment (62.3% vs. 76.6%, p=0.006), even in smaller than 0.5 cm (38.6% vs. 60.0%, p=0.011). Conclusion: Dual time time $^{18}F$-FDG PET/CT imaging was more useful than single time point $^{18}F$-FDG PET/CT imaging for distinction between PTMCa and benign nodule, especially when nodule showed equivocal or negative findings in single time point $^{18}F$-FDG PET/CT imaging or was smaller than 0.5 cm.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.5
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• pp.271-274
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• 2006

We report the case of a 64-year-old man with superior vena cava (SVC) syndrome due to tumor thrombus from recurrent hepatocellular carcinoma (HCC). He presented with new onset of facial swelling for 10 days. HCC was detected ten years ago. He has undergone repeated transcatheter arterial embolization (TAE) and chemotherapy. Chest computed tomography (CT) demonstrated tumor thrombus in the SVC extending to right atrium. He underwent whole body F-18 fluorodeoxyglucose(FDG) positron emission tomography/computed tomography (PET/CT) scanning for assessing the effect of TAE in HCC. F-18 FDG PET/CT showed increased uptake in the residual liver mass indicating viable tumor. There was another intense F-18 FDG accumulation in SUV extending to right atrium to suggest tumor thrombus. This case illustrates that F-18 FDG PET/CT is useful to identification of distant metastases as well as assessment of response to therapy in long-term survival HCC patients.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.sup1
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• pp.130-133
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• 2008

Adrenal tumors are increasingly detected by widespread use of anatomical imaging such as a, MRI, etc. For these adrenal tumors, differentiation between malignancy and benignancy is very important. In diagnostic assessment of adrenal tumor, $^{18}F-FDG$ PET and PET-CT have been reported to have high diagnostic performance, especially, very excellent performance in evaluation of adrenal metastasis in the oncologic patient. In cases of adrenal incidentalomas, $^{18}F-FDG$ PET or PET-CT is helpful if a or chemical-shift MRI is inconclusive. $^{18}F-FDG$ PET and PET-CT may be applied to the patients with MIBG-negative pheochromocytomas. In summary, $^{18}F-FDG$ PET and PET-CT are expected to be effective diagnostic tools in the management of adrenal tumor.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.1
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• pp.79-80
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• 2008

Including malignancy, various disease can show abnormal uptake in bone marrow. We report a case of non-specific inflammatory FDG uptake in bone marrow mimicking malignancy. A 35-year old woman with fever of unknown origin (FUO) underwent $^{18}F$-FDG PET/CT to find out fever $^{18}F$-FDG and unknown malignancy. $^{18}F$-FDG was injected and imaged 1hr after injection with Discovery ST (GE, USA), $^{18}F$-FDG PET/CT whole body image showed abnormal uptake in lower extremities (Fig. 1). MRI and biopsy was also done in the sites of abnormal uptake. PET and MRI suspect malignancy (Fig. 2, 3), but biopsy result was non-specific inflammatory process (Fig. 4). The patient was improved her clinical condition after antibiotics therapy.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.8-11
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• 2012

Purpose : Among quality control items, the radiochemical impurity must be below 10% of total radioactivity. In this regard, as the recently commercialized automatic synthesis module produces a large amount of 18F-FDG, radiolysis of radiopharmaceuticals is very likely to occur. Thus, this study compared the changes in radiochemical purity regarding radiolysis of $^{18}F$-FDG according to automatic synthesis module. Materials and methods : Cyclotron (PETtrace, GE Healthcare) was used to produce $^{18}F$ and automatic synthesis module (FASTlab, Tracerlab MX, GE Healthcare) was used to achieve synthesis into FDG. For radiochemical purity, Radio-TLC Scanner (AR 2000, Bioscan), GC (Gas Chromatograph, Agilent 7890A) was used to measure the content of ethanol included in $^{18}F$-FDG. Glass board applied with silica gel ($1{\times}10cm$) was used for stationary phase while a mixed liquid formed of acetonitrile and water (ratio 19:1) was used for mobile phase. High-concentration and low-concentration $^{18}F$-FDG were produced in each synthesis module and the radiochemical purity was measured every 2 hours. Results : The purity in low-concentration (below 2.59 GBq/mL) was measured as 99.26%, 98.69%, 98.25%, 98.09% in Tracerlab MX and as 99.09%, 97.83%, 96.89%, 96.62% in FASTlab according to 0, 2, 4, 6 hours changes, respectively. The purity in high-concentration (above 3.7 GBq/mL) was measured as 99.54%, 96.08%, 93.77%, 92.54% in Tracerlab MX and as 99.53%, 95.65%, 92.39%, 89.82% in FASTlab according to 0, 2, 4, 6 hours changes, respectively. Also, ethanol was not detected in GC of $^{18}F$-FDG produced in FASTlab, while 100~300 ppm ethanol was detected in Tracerlab MX. Conclusion : Whereas the change of radiochemical purity was only 3% in low-concentration $^{18}F$-FDG, the change was rapidly increased to 10% in high-concentration. Also, higher radiolysis were observed in $^{18}F$-FDG produced in FASTlab than Tracerlab MX. This is because ethanol is included in the synthesis stage of Tracerlab MX but not in the synthesis stage of FASTlab. Thus, radiolysis is influenced by radioactivity concentration than the inclusion of ethanol, which is the radioprotector. Therefore, after producing high-concentration $^{18}F$-FDG, the content must be diluted through saline to lower concentration.

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.2
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• pp.9-13
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• 2016

Purpose PET-CT examinations using $^{18}F-FDG$ to treat urinary system cancer are limited in terms of anatomical structure and excretion route of $^{18}F-FDG$. But one of the ongoing examinations utilizing $^{11}C-Acetate$ can compensate for such defects. We would like to introduce a clinical application of $^{11}C-Acetate$ PET-CT in urinary cancer patients. Materials and Methods We conducted a clinical survey of 22 patients diagnosed with urinary cancer at our hospital, 10 prostate cancer patients, 10 renal cell carcinoma patients, and 2 bladder cancer patients. All patients were performed $^{18}F-FDG$ PET-CT examinations, $^{11}C-Acetate$ examinations were performed after two weeks on average. The equipment used to D-710 PET-CT in GE Company and we performed PET-CT procedures 15 minutes after injecting $^{11}C-Acetate$, and a medical doctor from the department of nuclear medicine appraised and compared images between $^{18}F-FDG$ and $^{11}C-Acetate$. Results According to our survey, prostate cancer patients generally had lower uptake of $^{18}F-FDG$ than other cancer patients did. In 2 out of 10 prostate cancer patients, metastasized cancer showed greater uptake in $^{11}C-Acetate$ than $^{18}F-FDG$. In renal cell carcinoma cases, 8 out of 10 patients displayed evidently greater uptake in $^{11}C-Acetate$ than $^{18}F-FDG$. We excluded bladder cancer cases in this study because uptake of $^{18}F-FDG$ in the bladder was too hot, the number of patients was insufficient, and the cases did not meet criteria such as the use of diuretics. Conclusion It is too premature to draw solid conclusions from the survey, since it involved only a small number of participants. However, there are a number of studies conducted abroad that prove the effectiveness of the $^{11}C-Acetate$ PET-CT examinations in treating urinary system cancer, and this study is still ongoing at our hospital. If the tests were to be conducted on a larger number of participants, this study could lead to numerous other potential research topics, such as the correlation between Prostatic specific antigen (PSA) values and $^{11}C-Acetate$ PET-CT, Gleason sum values from biopsy before surgery, Specificity, sensitivity, positive predictive value (PPV), negative predictive value (NPV) between $^{18}F-FDG$ PET-CT examinations and $^{11}C-Acetate$ PET-CT examinations in other urinary system cancers.