• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.56-60
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• 2009

Purpose: The various studies and efforts to develop program are in progress in the field of nuclear medicine for the purpose of reducing scan time. The Oncoflash is one of the programs used in whole body bone scan which allows to maintain the image quality while to reduce scan time. When Those applications are used in clinical setting, both the image quality and reduction of scan time should be considered, therefore, the purpose of this study was to determine the criteria for proper scan speed. Materials and Methods: The subjects of this study were the patients who underwent whole body bone scan at the departments of nuclear medicine in the Asan Medical Center located in Seoul from 1st to 10th, July, 2008. The whole body bone images obtained in the scan speed of 30cm/min were classified by the total counts into under 800 K, and over 800 K, 900 K, 1,000 K, 1,500 K, and 2,000 K. The image quality were assessed qualitatively and the percentages of those of 1,000K and under of total counts were calculated. The FWHM before and after applying the Oncoflash were analyzed using images obtained in $^{99m}Tc$ Flood and 4-Quadrant bar phantom in order to compare the resolution according to the amount of total counts by the application of the Oncoflash. Considering the counts of the whole body bone scan, the dosed 2~5 mCi were used. 152 patients underwent the measurement in which the counts of Patient Postioning Monitor (PPM) were measured with including head and the parts of chest which the starting point of whole body bone scan from 7th to 26th, August, 2008. The correlations with total counts obtained in the scan speed of 30cm/min among them were analyzed (The exclusion criteria were after over six hours of applying isotopes or low amount of doses). Results: The percentage of the whole body bone image which has the geometric average of total counts of under 1,000K among them obtained in the scan speed of 30cm/min were 17.6%(n=58) of 329 patients. The qualitative analysis of the image groups according to the whole body counts showed that the images of under 1,000K were assessed to have coarse particles and increased noises. The analysis on the FWHM of the images before and after applying the Oncoflash showed that, in the case of PPM counts of under 3.6 K, FWHM values after applying the Oncoflash were higher than that before applying the Oncoflash, whereas, in the case of that of over 3.6 K, the FWHM after applying the Oncoflash were not higher than that before applying the Oncoflash. The average of total counts at 2.5~3.0 K, 3.1~3.5 K, 3.6~4.0 k, 4.1~4.5 K, 4.6~5.0 K, 5.1~6.0 K, 6.1~7.0 K, and 7.1 K over (in PPM) were $965{\pm}173\;K$, $1084{\pm}154\;K$, $1242{\pm}186\;K$, $1359{\pm}170\;K$, $1405{\pm}184\;K$, $1640{\pm}376\;K$, $1,771{\pm}324\;K$, and $1,972{\pm}385\;K$, respectively and the correlations between the counts in PPM and the total counts of image obtained in the scan speed of 30 cm/min demonstrated strong correlation (r=.775, p<.01). Conclusions: In the case of PPM coefficient over 3.6 K, the image quality obtained in the scan speed of 30cm/min and after applying the Oncoflash was similar to that obtained in the scan speed of 15 cm/min. In the case of total counts over 1,000 K, it is expected to reduce scan time without any damage on the image quality. In the case of total counts under 1,000 K, however, the image quality were decreased even though the Oncoflash is applied, so it is recommended to perform the re-image in the scan speed of 15 cm/min.

• The Korean Journal of Nuclear Medicine
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• v.31 no.1
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• pp.73-82
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• 1997

Regional myocardial blood flow (rMBF) can be noninvasively quantified using N-13 ammonia and dynamic positron emission tomography (PET). The quantitative accuracy of the rMBF values, however, is affected by the distortion of myocardial PET images caused by finite PET image resolution and cardiac motion. Although different methods have been developed to correct the distortion typically classified as partial volume effect and spillover, the methods are too complex to employ in a routine clinical environment. We have developed a refined method incorporating a geometric model of the volume representation of a region-of-interest (ROI) into the two-compartment N-13 ammonia model. In the refined model, partial volume effect and spillover are conveniently corrected by an additional parameter in the mathematical model. To examine the accuracy of this approach, studies were performed in 9 coronary artery disease patients. Dynamic transaxial images (16 frames) were acquired with a GE $Advance^{TM}$ PET scanner simultaneous with intravenous injection of 20 mCi N-13 ammonia. rMBF was examined at rest and during pharmacologically (dipyridamole) induced coronary hyperemia. Three sectorial myocardium (septum, anterior wall and lateral wall) and blood pool time-activity curves were generated using dynamic images from manually drawn ROIs. The accuracy of rMBF values estimated by the refined method was examined by comparing to the values estimated using the conventional two-compartment model without partial volume effect correction rMBF values obtained by the refined method linearly correlated with rMBF values obtained by the conventional method (108 myocardial segments, correlation coefficient (r)=0.88). Additionally, underestimated rMBF values by the conventional method due to partial volume effect were corrected by theoretically predicted amount in the refined method (slope(m)=1.57). Spillover fraction estimated by the two methods agreed well (r=1.00, m=0.98). In conclusion, accurate rMBF values can be efficiently quantified by the refined method incorporating myocardium geometric information into the two-compartment model using N-13 ammonia and PET.

• Parasites, Hosts and Diseases
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• v.29 no.3
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• pp.235-244
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• 1991

An epidemiological study and mass treatments of Enterobius vermicularis infection among children near Wonju area of Kangwon province were carried out. The children were divided into 4 groups according to their residing localities; children in the mountainous area, rural area, urban area and in orphanage. They were examined by adhesive cellotape anal swab technique, and egg positive rates were obtained. The rates of egg reduction and re-infection rates after repeated mass treatments were also observed. The results obtained were as follows: 1. The overall egg Positive rate of E. vermicularis in the first screening was 19.9% (251 out of 1, 262 examinees; 19.7% in males and 20.1% in females). The positive rates were 13.0% in the mountainous area, 11 9% in the rural area, 15.1% in the urban (medium-sized) area and 61.9% in orphanages. 2. The highest positive rates were observed in the kindergarten children, and 1st and 2nd grade children of primary schools (26.2~32.2%), and the lowest rate (13.6%) in 6-year grade children of primary schools. 3. Cumulative detection rates from 3 repeated anal swabs at 4~5 days interval were higher (70.8%) than those from single anal swabs (50.0~59.2%). 4. Out of the examinees who showed the highest cumulative positive rate (70.8%), about 39.2% were consecutively positive in 3 anal swabs. Among different groups of children, the higher the total egg detection rates (87.5%), the higher the consecutive positive rates (71.9%) . 5. A total of 2, 609 (male : female=1 : 12.4) worms were collected from 17 egg-positive cases treated with anthelinintics. The mean number of worms per child was 153 (range: 4-824) . 6. The egg-positive cases in several studied groups (180 children) were treated with anthelmintics 6 times at 3-week intervals. In this case, the overall positive rate was decreased from 54.8% to 2.2% at 15 weeks after the treatments, but no complete negative conversion was experienced. However, in a group of children (154 children) including egg Positive and negative cases who were both treated with anthelmintics at 3-week interval, a complete egg-negative conversion was observed in the 9th week after treatments. 7. The egg-detection rate in the brothers or sisters of egg Positive children was 70.0% (28 out of 40 examined), and the egg-positive rate according to the family unit was 69.7%. In summarizing the above results, it is concluded that Enterobius vermicularis infection is still highly prevalent among children in Korea, and that repeated mass treatments of more than 3 times will be effective for control of this infection.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.3
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• pp.195-214
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• 2020

The Samgwang Au-Ag deposit has been one of the largest deposits in Korea. The deposit consists of eight lens-shaped quartz veins which filled fractures along fault zones in Precambrian metasedimentary rock, which feature suggest that it is an orogenic-type deposit. The Ti-bearing minerals occur in wallrock (titanite, ilmenite and rutile) and laminated quartz vein (rutile). They occur minerals including biotite, muscovite, chlorite, white mica, monazite, zircon, apatite in wallrock and white mica, chlorite, arsenopyrite in laminated quartz vein. Chemical composition of titanite has maximum vaules of 3.94 wt.% (Al₂O₃), 0.49 wt.% (FeO), 0.52 wt.% (Nb₂O₅), 0.46 wt.% (Y₂O₃) and 0.43 wt.% (V₂O₅). Titanite with 0.06~0.14 (Fe/Al ratio) and 0.06~0.15 (X_Al (=Al/Al+Fe³⁺+Ti)) corresponds with metamorphic origin and low-Al variety. Chemical composition of ilmenite has maximum values of 0.07 wt.% (ZrO₂), 0.12 wt.% (HfO₂), 0.26 wt.% (Nb₂O₅), 0.04 wt.% (Sb₂O₅), 0.13 wt.% (Ta₂O₅), 2.62 wt.% (As₂O₅), 0.29 wt.% (V₂O₅), 0.12 wt.% (Al₂O₃) and 1.59 wt.% (ZnO). Chemical composition of rutile in wallrock and laminated quartz vein has maximum values of 0.35 wt.%, 0.65 wt.% (HfO₂), 2.52 wt.%, 0.19 wt.% (WO₃), 1.28 wt.%, 1.71 wt.% (Nb₂O₃), 0.03 wt.%, 0.07 wt.% (Sb₂O₃), 0.28 wt.%, 0.21 wt.% (As₂O₅), 0.68 wt.%, 0.70 wt.% (V₂O₃), 0.48 wt.%, 0.59 wt.% (Cr₂O₃), 0.70 wt.%, 1.90 wt.% (Al₂O₃) and 4.76 wt.%, 3.17 wt.% (FeO), respectively. Rutile in laminated quartz vein is higher contents (HfO₂, Nb₂O₃, As₂O₅, Cr₂O₃, Al₂O₃ and FeO) and lower content (WO₃) than rutile in wallrock. The substitutions of rutile in wallrock and laminated quatz vein are as followed : rutile in wallrock [(Fe³⁺, Al³⁺, Cr³⁺) + Hf⁴⁺ + (W⁵⁺, As⁵⁺, Nb⁵⁺) ⟵⟶ 2Ti⁴⁺ + V⁴⁺, 2Fe²⁺ + (Al³⁺, Cr³⁺) + Hf⁴⁺ + (W⁵⁺, As⁵⁺, Nb⁵⁺) ⟵⟶ 2Ti⁴⁺ + 2V⁴⁺], rutile in laminated quartz vein [(Fe³⁺, Al³⁺) + As⁵⁺ ⟵⟶ Ti⁴⁺ + V⁴⁺, (Fe³⁺, Al³⁺) + As⁵⁺ ⟵⟶ Ti⁴⁺ + Hf⁴⁺, 4(Fe³⁺, Al³⁺) ⟵⟶ Ti⁴⁺ + (W⁵⁺, Nb⁵⁺) + Cr³⁺], respectively. Based on these data, titanite, ilmenite and rutile in wallrock were formed by resolution and reconcentration of cations (W⁵⁺, Nb⁵⁺, As⁵⁺, Hf⁴⁺, V⁴⁺, Cr³⁺, Al³⁺, Fe³⁺, Fe²⁺) in minerals of wallrock during regional metamorphism. And then rutile in laminated quartz vein was formed by reconcentration of cations (Nb⁵⁺, As⁵⁺, Hf⁴⁺, Cr³⁺, Al³⁺, Fe³⁺, Fe²⁺) in alteration minerals (white mica, chlorite) and Ti-bearing minerals reaction between hydrothermal fluid originated during ductile shear and Ti-bearing minerals (titanite, ilmenite and rutile) in wallrock.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.1
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• pp.30-41
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• 2007

Purpose: Bone metastasis in breast cancer patients are usually assessed by conventional Tc-99m methylene diphosphonate whole-body bone scan, which has a high sensitivity but a poor specificity. However, positron emission tomography with $^{18}F-2-deoxyglucose$ (FDG-PET) can offer superior spatial resolution and improved specificity. FDG-PET/CT can offer more information to assess bone metastasis than PET alone, by giving a anatomical information of non-enhanced CT image. We attempted to evaluate the usefulness of FDG-PET/CT for detecting bone metastasis in breast cancer and to compare FDG-PET/CT results with bone scan findings. Materials and Methods: The study group comprised 157 women patients (range: $28{\sim}78$ years old, $mean{\pm}SD=49.5{\pm}8.5$) with biopsy-proven breast cancer who underwent bone scan and FDG-PET/CT within 1 week interval. The final diagnosis of bone metastasis was established by histopathological findings, radiological correlation, or clinical follow-up. Bone scan was acquired over 4 hours after administration of 740 MBq Tc-99m MDP. Bone scan image was interpreted as normal, low, intermediate or high probability for osseous metastasis. FDG PET/CT was performed after 6 hours fasting. 370 MBq F-18 FDG was administered intravenously 1 hour before imaging. PET data was obtained by 3D mode and CT data, used as transmission correction database, was acquired during shallow respiration. PET images were evaluated by visual interpretation, and quantification of FDG accumulation in bone lesion was performed by maximal SUV(SUVmax) and relative SUV(SUVrel). Results: Six patients(4.4%) showed metastatic bone lesions. Four(66.6%) of 6 patients with osseous metastasis was detected by bone scan and all 6 patients(100%) were detected by PET/CT. A total of 135 bone lesions found on either FDG-PET or bone scan were consist of 108 osseous metastatic lesion and 27 benign bone lesions. Osseous metastatic lesion had higher SUVmax and SUVrel compared to benign bone lesion($4.79{\pm}3.32$ vs $1.45{\pm}0.44$, p=0.000, $3.08{\pm}2.85$ vs $0.30{\pm}0.43$, p=0.000). Among 108 osseous metastatic lesions, 76 lesions showed as abnormal uptake on bone scan, and 76 lesions also showed as increased FDG uptake on PET/CT scan. There was good agreement between FDG uptake and abnormal bone scan finding (Kendall tau-b : 0.689, p=0.000). Lesion showed increased bone tracer uptake had higher SUVmax and SUVrel compared to lesion showed no abnormal bone scan finding ($6.03{\pm}3.12$ vs $1.09{\pm}1.49$, p=0.000, $4.76{\pm}3.31$ vs $1.29{\pm}0.92$, p=0.000). The order of frequency of osseous metastatic site was vertebra, pelvis, rib, skull, sternum, scapula, femur, clavicle, and humerus. Metastatic lesion on skull had highest SUVmax and metastatic lesion on rib had highest SUVrel. Osteosclerotic metastatic lesion had lowest SUVmax and SUVrel. Conclusion: These results suggest that FDG-PET/CT is more sensitive to detect breast cancer patients with osseous metastasis. CT scan must be reviewed cautiously skeleton with bone window, because osteosclerotic metastatic lesion did not showed abnormal FDG accumulation frequently.