• Nuclear Medicine and Molecular Imaging
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• v.40 no.4
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• pp.228-232
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• 2006

Purpose: electrophilic $^{18}F(T_{1/2}=110\;min)$ radionuclide in the form of $[^{18}F]F_2$ gas is of great significance for labeling radiopharmaceuticals for positron omission tomography (PET). However, its production In high yield and with high specific radioactivity is still a challenge to overcome several problems on targetry. The aim of the present study was to develop a method suitable for the routine production of $[^{18}F]F_2$ for the electrophilic substitution reaction. Materials and Methods: The target was designed water-cooled aluminum target chamber system with a conical bore shape. Production of the elemental fluorine was carried out via the $^{18}O(p,n)^{18}F$ reaction using a two-step irradiation protocol. In the first irradiation, the target filled with highly enriched $^{18}O_2$ was irradiated with protons for $^{18}F$ production, which were adsorbed on the inner surface of target body. In the second irradiation, the mixed gas ($1%[^{19}F]F_2/Ar$) was leaded into the target chamber, fellowing a short irradiation of proton for isotopic exchange between the carrier-fluorine and the radiofluorine absorbed in the target chamber. Optimization of production was performed as the function of irradiation time, the beam current and $^{18}O_2$ loading pressure. Results: Production runs was performed under the following optimum conditions: The 1st irradiation for the nuclear reaction (15.0 bar of 97% enriched $^{18}O_2$, 13.2 MeV protons, 30 ${\mu}A$, 60-90 min irradiation), the recovery of enriched oxygen via cryogenic pumping; The 2nd irradiation for the recovery of absorbed radiofluorine (12.0 bar of 1% $[^{19}F]fluorine/argon$ gas, 13.2 MeV protons, 30 ${\mu}A$, 20-30 min irradiation) the recovery of $[^{18}F]fluorine$ for synthesis. The yield of $[^{18}F]fluorine$ at EOB (end of bombardment) was achieved around $34{\pm}6.0$ GBq (n>10). Conclusion: The production of $^{18}F$ electrophilic agent via $^{18}O(p,n)^{18}F$ reaction was much under investigation. Especially, an aluminum gas target was very advantageous for routine production of $[^{18}F]fluorine$. These results suggest the possibility to use $[^{18}F]F_2$ gas as a electrophilic substitution agent.

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.2
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• pp.42-45
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• 2016

Purpose Neuracep is used to other diagnostic evaluations of the brain to estimate beta-amyloid neuritic plaque density in adult patients with cognitive impairment and inspected cognitive impairment. $^{18}F-Florbetaben$ specially has moderate lipophilicity and property of the added ethanol. It is the subject of interest of the patient pain and residual activity after injecting. Our study is effective injection method of the radiopharmaceutical and patient care. So it is for the highest quality image. Materials and Methods Patients were targeted 70 subjects, it was injected mean $259{\pm}74MBq$ to the patients ($^{18}F-FDG$: 20 subjects, $^{18}F-FP-CIT$: 20 subjects, $^{18}F-Florbetaben$: 30 subjects). After injection (reflusing 2 times, reflusing 3 times) using a 3-way set, it measured the residual activity. When injecting $^{18}F-Florbetaben$, we evaluated the effective injection methods(3-way set method and heparin cap method). The average residual activity after the injection was compared using a statistical analysis of SPSS 12.0(ANOVA, t-test analysis). Also, elemental analysis was performed on $^{18}F-Florbetaben$ by GC (Gas Chromatography). Results When reflusing 2 times measured residual activity as follows ($^{18}F-FDG$: 1.48 MBq, $^{18}F-FP-CIT$: 7.4 MBq, $^{18}F-Florbetaben$: 32.6 MBq). And when reflusing 3 times measured residual activity as follows ($^{18}F-FDG$: 1.85 MBq, $^{18}F-FP-CIT$: 3.7 MBq, $^{18}F-Florbetaben$: 36.3 MBq). There was a significant difference when reflusing 2 times(P < 0.05) and reflusing 3 times (P < 0.05). But when reflusing 3 times, there was no significant difference relation FDG and FP-CIT (P > 0.05). $^{18}F-Florbetaben$ Residual activity according to the injection method was a significant difference (P < 0.05). GC analysis results were measured ethanol: 207665 ppm and acceton: 377.4 ppm. Conclusion $^{18}F-Florbetaben$ was high residual activity compared to FDG and FP-CIT. Heparin cap method was effective when $^{18}F-Florbetaben$ was injected. $^{18}F-Florbetaben's$ ethanol component analysis was highly measured. So it is recommended that inject to 6 sec/ml or more in order to reduce the pain.

• 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 $2,000Bq\;m^{-3}$.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.7 no.2
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• pp.153-159
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• 2021

This article provides an efficient ¹⁸F-labeling protocol based on a rapid condensation reaction between 2-cyanobenzothiazole (CBT) and N-terminal cysteine-containing biomolecules. The ¹⁸F-labeled CBT (¹⁸F-1) was prepared by radiofluorination of the tosylated precursor 4 with 18-crown-6/K+/[¹⁸F]F- complex. Using the purified ¹⁸F-1, ¹⁸F-labeled peptide (¹⁸F-7) and protein (¹⁸F-8) could be synthesized efficiently under mild conditions. This strategy would provide a convenient approach for rapid and site-specific ¹⁸F-labeling of various peptides and proteins for in vivo imaging and biomedical applications.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.91-96
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• 2005

O-(3-[$^{18}$F]Fluoropropyl)-L-tyrosine (L-[$^{18}$F]FPT) was synthesized by nucleophilic radiofluorination followed by acidic hydrolysis of protective groups and evaluated with 9 L tumor bearing rat. L-[$^{18}$F]FPT is an homologue of O-(2-[$^{18}$F]fluoroethyl)-L-tyrosine (L-[$^{18}$F]FET) which recently is studied as a tracer for tumor imaging using positron emission tomography (PET). [$^{18}$F]FPT was directly prepared from the precursor of O-(3-ptoluenesulfonyloxypropyl)- N-(tert-butoxycarbonyl)-L-tyrosine methyl ester. FPT-PET image was obtained at 60 min in 9 L tumor bearing rats. The radiochemical yield of [$^{18}$F]FPT was 0-45% (decay corrected) and the radiochemical purity was more than 95% after HPLC purification. The total time elapsed for the synthesis of [$^{18}$F]FPT was 100 min from EOB (End-of-bombardment). A comparison of uptake studies between [$^{18}$F]FPT and [$^{18}$F]FET was performed. In biodistribution, [$^{18}$F]FPT showed similar pattern with [$^{18}$F]FET in various tissues, but [$^{18}$F]FPT showed low uptake in brain. Furthermore, [$^{18}$F]FPT showed higher tumor-to-brain ratio than [$^{18}$F]FET. In conclusion, [$^{18}$F]FPT seems to be more useful amino acid tracer than [$^{18}$F]FET for brain tumors imaging with PET.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2177-2180
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• 2012

New [$^{18}F$]F-fluorination methods using a minimized amount of precursor has been developed by controlling the base concentration. In the first method, pre-conditioning of the anion exchange cartridge with $K_2CO_3$ solution or water was carried out. The trapped [$^{18}F$]fluoride on the cartridge was then eluted by KOMs or KOTf solution. [$^{18}F$]F-Fluorination could be performed without additional base. In the second method, the QMA cartridge was preconditioned with KOMs solutions. Trapped [$^{18}F$]fluoride on the QMA was then eluted with KOMs and additional base, such as KOH, $K_2CO_3$, and $KHCO_3$, was added into the reaction vessel. Method 1 showed a [$^{18}F$]F-incorporation yield of 20.9% for [$^{18}F$]FLT synthesis with 5 mg of precursor. Unlike method 1, a [$^{18}F$]F-incorporation yield of 91.4% was achieved from the same amount of precursor in method 2.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.sup1
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• pp.17-28
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• 2008

This review focuses on the clinical use of $^{18}F-FDG$ PET to evaluate solitary pulmonary nodule (SPN) and non-small cell lung cancer (NSCLC). When SPN or mass without calcification is found on chest X-ray or CT, $^{18}F-FDG$ PET is an effective modality to differentiate benign from malignant lesions. For initial staging of NSCLC, $^{18}F-FDG$ PET is useful, and proved to be cost-effective in several countries. $^{18}F-FDG$ is useful for detecting recurrence, restaging and evaluating residual tumor after curative therapy in NSCLC. For therapy response assessment, $^{18}F-FDG$ PET may be effective after chemotherapy or radiation therapy. $^{18}F-FDG$ PET is useful to predict pathological response after neoadjuvant therapy in NSCLC. For radiation therapy planning, $^{18}F-FDG$ PET may be helpful, but requires further investigations. PET/CT is better for evaluating NSCLC than conventional PET.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.sup1
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• pp.32-38
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• 2008

This review focuses on the clinical use of $^{18}F-FDG$ PET in esophageal cancer. For initial staging of esophageal cancer, $^{18}F-FDG$ PET is better than chest CT and is complementary to endoscopic ultrasound. Due to its good results for detecting distant metastasis, $^{18}F-FDG$ PET evades unnecessary curative surgery. Also, PET findings are associated with prognosis in esophageal cancer. $^{18}F-FDG$ PET seems to be useful for detecting recurrence and restaging in esophageal cancer. For therapy response assessment, $^{18}F-FDG$ PET is effective after chemotherapy or radiation therapy. $^{18}F-FDG$ PET is useful to predict pathological response after neoadjuvant therapy in esophageal cancer, which is better than chest CT and endoscopic ultrasound. For radiation therapy planning, $^{18}F-FDG$ PET may be helpful, but requires further investigations.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.6
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• pp.3647-3652
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• 2013

Purpose: To evaluate the diagnostic value of $^{18}F$-FDG PET/CT for detection of bone metastasis in comparison with the efficacies of $^{18}F$-FDG PET/CT, CT, $^{18}F$-FDG PET and conventional planar bone scintigraphy in a series of cancer patients. Methods: Five hundred and thirty patients who underwent both $^{18}F$-FDG PET/CT and bone scintigraphy within 1 month were retrospectively analyzed. The skeletal system was classified into 10 anatomic segments and interpreted blindly and separately. For each modality, the sensitivity, specificity, accuracy, PPV and NPV were calculated and the results were statistically analyzed. Results: Bone metastases were confirmed in 117 patients with 459 positive segments. On patient-based analysis, the sensitivity, specificity, accuracy, PPV and NPV of $^{18}F$-FDG PET/CT were significantly higher than bone scintigraphy, CT and $^{18}F$-FDG PET (P<0.05). On segment-based analysis, the sensitivity of CT, bone scintigraphy, $^{18}F$-FDG PET and $^{18}F$-FDG PET/CT were 70.4%, 89.5%, 89.1% and 97.8%, respectively (P<0.05, compared with $^{18}F$-FDG PET/CT). The overall specificity and accuracy of the four modalities were 89.1%, 91.8%, 90.3%, 98.2% and 90.3%, 90.9%, 89.8%, 98.0%, respectively (P<0.05, compared with $^{18}F$-FDG PET/CT). The PPV and NPV were 89.8%, 87.6%, 85.6%, 97.2% and 85.6%, 93.2%, 92.8%, 98.6%, respectively. Three hundred and twelve lesions or segments were presented as lytic or sclerotic changes on CT images at the corresponding sites of increased $^{18}F$-FDG uptake. In lytic or mixed lesions, the sensitivity of $^{18}F$-FDG PET/CT and $^{18}F$-FDG PET were better than bone scintigraphy, while in osteoblastic lesions bone scintigraphy had a similar performance with $^{18}F$-FDG PET/CT but better than $^{18}F$-FDG PET alone. Conclusion: Our data allow the conclusion that $^{18}F$-FDG PET/CT is superior to planar bone scintigraphy, CT or $^{18}F$-FDG PET in detecting bone metastasis. $^{18}F$-FDG PET/CT may enhance our diagnosis of tumor bone metastasis and provide more information for cancer treatment.

• Korean Journal of Clinical Laboratory Science
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• v.55 no.4
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• pp.261-268
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• 2023

[¹⁸F]Fluorocholine is a radiopharmaceutical used non-invasively in positron emission tomography to diagnose parathyroid adenoma, prostate cancer, and hepatocellular carcinoma by evaluating the choline metabolism. In this study, a radiolabeling method for [¹⁸F]fluorocholine was optimized using a solid phase extraction (SPE) cartridge. [¹⁸F]Fluorocholine was labeled in two steps using an automated synthesizer. In the first step, dibromomethane was reacted with [¹⁸F]KF/K2.2.2/K₂CO₃ to obtain the intermediate [¹⁸F]fluorobromomethane. In the second step, [¹⁸F]fluorobromomethane was passed through a Sep-Pak^Ⓡ Silica SPE cartridge to remove the impurities and then reacted with N,N-dimethylaminoethanol (DMAE) in a Sep-Pak^Ⓡ C18 SPE cartridge to label [¹⁸F]fluorocholine. The reaction conditions of [¹⁸F]fluorocholine were optimized. The synthesis yield was confirmed according to the number of silica cartridges and DMAE concentration. No statistically significant difference in the synthesis yield of [¹⁸F]fluorocholine was observed when using four or three silica cartridges (P>0.05). The labeling yield was 11.5±0.5% (N=4) when DMAE was used as its original solution. On the other hand, when diluted to 10% with dimethyl sulfoxide, the radiochemical yield increased significantly to 30.1±5.2% (N=20). In conclusion, [¹⁸F]Fluorocholine for clinical use can be synthesized stably in high yield by applying an optimized synthesis method.