• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.86-90
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• 2012

Purpose: Quantification of myocardial blood flow (MBF) using dynamic PET imaging has the potential to assess coronary artery disease. Rb-82 plays a key role in the clinical assessment of myocardial perfusion using PET. However, MBF could be overestimated due to the underestimation of left ventricular input function in the beginning of the acquisition when the scanner has non-linearity between count rate and activity concentration due to the scanner dead-time. Therefore, in this study, we evaluated the count rate linearity as a function of the activity concentration in PET data acquired in list mode. Materials & methods: A cylindrical phantom (diameter, 12 cm length, 10.5 cm) filled with 296 MBq F-18 solution and 800 mL of water was used to estimate the linearity of the Biograph 40 True Point PET/CT scanner. PET data was acquired with 10 min per frame of 1 bed duration in list mode for different activity concentration levels in 7 half-lives. The images were reconstructed by OSEM and FBP algorithms. Prompt, net true and random counts of PET data according to the activity concentration were measured. Total and background counts were measured by drawing ROI on the phantom images and linearity was measured using background correction. Results: The prompt count rates in list mode were linearly increased proportionally to the activity concentration. At a low activity concentration (<30 kBq/mL), the prompt net true and random count rates were increased with the activity concentration. At a high activity concentration (>30 kBq/mL), the increasing rate of the prompt net true rates was slightly decreased while the increasing rate of random counts was increased. There was no difference in the image intensity linearity between OSEM and FBP algorithms. Conclusion: The Biograph 40 True Point PET/CT scanner showed good linearity of count rate even at a high activity concentration (~370 kBq/mL).The result indicates that the scanner is useful for the quantitative analysis of data in heart dynamic studies using Rb-82, N-13, O-15 and F-18.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.3-7
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• 2014

Purpose SPECT/CT scan to be performed attenuation correction on the basis of CT induce an overestimation of the site due to the beam hardening artifact by metal cover and reduce the images quality. Therefore, this study using a phantom that has been inserted artificial hip joint investigated that effect on the SPECT/CT image causing by metal artifact for varying the parameters of the Attenuation Map. Materials and Methods Siemens Symbia T16 SPECT/CT equipment was used. Artificial hip joint was inserted to SPECT/PET phantom, 17 mm sphere of Bright Streak area in CT image was filled with Tc-99m so that the radiation activity was 8 times compared to background. And then Hot and Background was measured in varying Wide Beam Coefficient on Attenuation Map and RBR (Region to Background Ratio) of Metal and Non-Metal was calculated and analyzed depending on the presence or absence of the hip joint. Results It tended to hot count of Non-Metal and Metal to increase as the value of the manual mode is increased, hot count ratio with the group of both manual mode 0.5 and 0.4 is the best match. Also, in automatic mode, the ratio of RBRNon-Metal and RBRMetal was 1.135, statistically significant difference was not observed in the manual mode 0.5 and 0.4. Conclusion In the automatic mode of Wide Beam Coefficient in attenuation correction map, it was found that it is over-correction by 13.52%, it was possible to minimize the over-correction by the artifact in 0.5 and 0.4 of manual mode. Further studies should be performed in order to apply to a patient with the help of this and it is considered possible to reduce the over-correction by the metal artifact of an artificial hip joint for Hip-Resurfacing Arthroplasty patients, and to improve the diagnostic performance.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.17-20
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• 2010

Purpose: The hepatobiliary scan is the examination which is the possibility of knowing the function of liver, gall bladder and closing of the biliary tract. Also, after subtotal gastrectomy, the increased gastric-bile reflux is known as the primary reason of reflux gastritis. In this study, according to changing the acquisition method, we tried to prove the reflux time and reflux index in patients who underwent subtotal gastrectomy. Materials and Methods: From Oct 2008 to Jan 2009, 72 patients with subtotal gastrectomy who took the hepatobiliary scan (man: 52, woman: 20, age range: 31-77, mean age: $60.5{\pm}7$) in our department. We used the radiopharmaceutical $^{99m}Tc$-mebrofenin 185 MBq/0.5 cc. After 5 minutes, we acquired 300,000 counts anterior image on supine, and then we acquired right lateral and $45^{\circ}$ LAO position by using the time setting method. We acquired 30 min, 60 min, 90 min, 120 min and fatty meal by the same method. We painted the ROI of liver, GB and CBD on 30 min anterior image and LAO image in patients had occurred the bile juice reflux. And then we painted the ROI of stomach on others image. We calculated the reflux index from those values. Results: According to this study, we found out 40 patients (55.6%) who had occurred the gastric-bile juice reflux (1 person from 30 min, 7 persons from 60 min, 4 persons from 90 min, 28 persons from after fatty meal). Hourly, the bile reflux highest level is 6 persons from 60 min, 2 persons from 90 min, 32 persons from fatty meal among those people. The reflux index of anterior is 0.85-23.36% (mean 6.53%). The reflux index of LAO is 1-29.13% (mean 8.89%). By visual assessment, we can distinguish that there were 26 of the 40 patients (65%) had occurred the reflux on LAO image more than anterior image. Conclusion: We find out that the patients with subtotal gastrectomy had occurred gastric-bile juice reflux more than 50% from hepatobiliary scan. And after eating fatty meal, we can know that it's the most possible to occur the gastric-bile juice reflux. When it happened, we have to change the acquisition method to reduce the overlap between colon and stomach. This study will be more valuable in diagnosis.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.41-44
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• 2010

Purpose: Along with recent advances in PET/CT instrumentation and imaging technology, the number of patients has also been steadily increasing. This resulted in the increased radiation exposure to radiation workers in PET/CT rooms. In this study, we installed a radiation shield and investigated whether it could reduce radiation exposure to the workers and thus enhance job satisfaction. Materials and Methods: A radiation shield is composed of 5 cm thick lead and has a structure in which a radiation worker sits and watches a patient through lead glass while injecting radiopharmaceutical to the patient. Quarterly absorbed dose of radiation workers was measured using thermoluminescence dosimeters (TLD) and the results were compared for six months each before and after installation of the radiation shield. Exposure dose was also measured using a pocket dosimeter placed at the same location in the front and the back of the radiation shield. In addition, frequency of use of the shield and job satisfaction of radiation workers were investigated using a survey. Results: Quarterly absorbed dose of radiation workers was 2.70 mSv on average before installation of new radiation shield, whereas that dropped to 2.13 mSv after installation of radiation shield, reducing radiation exposure dose by 21%. Exposure dose on the front side of the shield was 61.2 R, whereas that on the back side of shield was 2.8 R. According to the survey, 85% of workers used the shield and were satisfied with the outcome: each radiation worker made injections to patients average of 6.5 times/day and preferred sitting to standing while injecting radiopharmaceutical to patients. Conclusion: Use of radiation shield reduced the exposure dose of radiation workers, which is the ultimate goal of radiation protection to minimize radiation exposure and is an appropriate method for the improvement of hospital working environment. Furthermore, we found that use of radiation shield not only relieves physical and psychological burden of radiation workers but also enhances job satisfaction. This result indicates that use of radiation shield is important for improvement of the radiation workers' job environment in terms of radiation protection.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.177-180
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• 2010

Purpose: As PET test came to be covered by the pay system of medical insurance (July 1, 2006) and the needs for it becoming increased for laboratory purpose, it became necessary to purchase expensive medical equipments to solve those problems. However, as most of equipments that are operated by cyclotron are very expensive as to amount from tens of millions up to hundreds of millions of won, it is difficult to purchase those equipments from the point of medical organizations. It may be possible to self manufacture those equipments with least costs if their parts functions that meets the operators demands. The Nuclear Medicine department of National Cancer Center (NCC) is trying to manufacture and use equipments that can be made with least costs, including introducing 2 medical equipments that can improves the operator's works. Materials and Methods: Example 1: Self production of radioisotope($^{18}F$) divider was fabricated. The NCC's Nuclear Medicine department acquired one acrylic panel, seven 3-way valve, tubing etc. that can be found in the market to make the main body of divider in cooperation with biomedical engineering, and placed them inside hot cell, and installed switching box outside of hot cell to make it possible to control them from outside. This main body of divider were placed in radioisotope transfer line that are manufactured in the cyclotron. Example 2: Self production of $^{18}F$-FDG automated divider was fabricated. The NCC's Nuclear Medicine department used cavro pump syringe that consists the main body of divider in cooperation with biomedical engineering, biomedical engineering developed programs that divides a certain amount. $^{18}F$-FDG automated divider is placed inside hot cell, and cable chords were used in the equipment, and then it was connected to PC outside hot cell to make it possible to control the $^{18}F$-FDG automated divider. Results: From the NCC's Nuclear Medicine department tests that were carried out from March, 2007 until now, we found out that radioisotope can be sent to radiopharmaceuticals composite module we want, and from the tests that are carried out at NCC's Nuclear Medicine department using $^{18}F$-FDG automated divider since August, 2009 it was possible to distribute radiopharmaceuticals into vial intended. Conclusion: Through the two examples above, we found out that costs can be reduced by self manufacturing expensive equipments from NCC's cyclotron room with least costs. Also, it decreased radiation exposure dose on workers, and set up problem solving processes in cooperation with lots of parties related.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.155-158
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• 2010

Purpose: $^{99m}Tc$-macroaggregated albumin (MAA) hepatic arterial perfusion scintigraphy was known for useful method to evaluate patients receiving intraarterial chemotherapy for liver cancer. This study evaluate about usefulness of normal liver on hepatocellular carcinoma (HCC) from HCC patients. This study is to see the usefullness of Hepatic Arterial Perfusion Scintigraphy (HAPS) by measuring mass size, shape, lung shunting and tumor to normal ratio (T/N ratio) in relative blood stream of HCC patients compared with HCC on normal liver. Materials and Methods: From June 2009 to September 2009, HAPS studies were performed on 7 patients (men 6, women 1, mean 64) who were diagnosed HCC. HAPS was performed after proper hepatic artery $^{99m}Tc$-MAA of 5 mCi (185 MBq) injection by catheter. We performed anterior, posterior, both lateral view, SPECT of chest and abdomen. Then we set up ROI and calculated lung shunting, T/N ratio for each count, count/pixel (mean value). Results: Tumor and liver size analyzed by ROI of anterior, posterior view are 2.0-10.8 cm (mean 3.75 cm), 8.8-18.5 cm (mean 14.6 cm). T/N ratio analyzed by total tumor and total normal mean value are 2.41-5.76 (mean 3.8). lung shunting analyzed by total liver count is 3.14-13.92% (mean 6.77%). Conclusion: HAPS with $^{99m}Tc$-MAA can evaluate mass size, location, quantitative analysis through T/N ratio. also HAPS can evaluate detection of arteriovenous shunt through lung uptake before radioisotope therapy. Therefore HAPS with $^{99m}Tc$-MAA can be useful method in aspect of evaluation and treatment of HCC.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.138-144
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• 2010

Purpose: Despite the rapidly changing healthcare environment, healthcare organizations have recognized the importance of patient safety management. But patient safety management has the problem of the lack of participation of members due to the process of focusing on the follow-up service and punishment. The department of nuclear medicine in Uijeongbu St. Mary's Hospital started this research to reduce the near miss and prevent patient safety accidents by both initiating the participatory near-miss-proof activities as an advance management and constructing a system without disadvantages of reporting. In addition, this research aims to establish a differentiated patient safety management system in the department of nuclear medicine. Materials and Methods: 1. Colleting cases of team members' past and present near miss and accidents(First data collection). 2. Quantifying the cases of near miss and accidents after identifying the degree of importance and urgency through surveys(Second data collection). 3. Quantifying cases and indentifying important points of contact through data analysis. 4. Making and standardizing a manual for important points of contact, and initiating participatory activities to prevent errors. 5. Activating web-based community for establishing the report system of near miss. 6. Estimating the result of before and after activities through surveys and focus group interviews. Results: 1) Quantified safety accidents and near miss in the department of nuclear medicine. About 50 near misses a month and one safety accident a year. 2) Establishing improvement measurements based on quantified data. About 11 participatory activities, the improvement of process, a manual for standardization. 3) Creating a system of safety culture and high participation rate of team members. Constructing a report system, making a check list and a slogan for safety culture, and establishing assessment index. 4) Activating communities for sharing the information of cases of near misses and accidents. 5) As the result of activities, the rate of near miss occurrence declined by 50% and the safety accident did not happen. Conclusion: The best service in the department of nuclear medicine is to provide patients with safety-guaranteed high-quality examination and cure. This research started from the question, 'what is the most faithful-to-the-basics way to provide the best service for patients?' and team members' common answer for this question was building a system with participation of all members. Building a system through the participatory improvement activities for preventing near miss and creating safety culture resulted in the 50% decline of near miss occurrence and no accident. This is a meaningful result from the perspective of advance management for patient safety. Moreover, this research paved the way for creating a culture to report and admit near miss or accidents by establishing a report system with no disadvantage of reporting. The system which sticks to the basics is the best service for patients and will form a patient safety culture system, which will lead to the customer satisfaction. Therefore, all members of the department of nuclear medicine will develop a differentiated patient safety culture with stabilizing the established system.

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.2
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• pp.75-79
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• 2016

Purpose The ASAN Medical Center, Nuclear Medicine performs TSH (Thyroid stimulating hormone) and FT4 (Free Thyroxine) tests 8 times per day. Accordingly, 70 ~ 80 kit tubes are consumed every day for the measurements and the time consumed for reagent dispensing averages over 170 seconds, where the TAT (turnaround time) may be effected when the number of test samples is larger than expected. Therefore, the following test was conducted with the purpose to reduce the number of kit tubes consumed, and reduce the time for reagent dispensing. Materials and Methods The test is based on applying the same reagent for tests where the number of samples is 30 or less. The test for TSH was conducted 9 times from July $1^{st}$ 2015 to July $10^{th}$ 2015. The test for FT4 was conducted 4 times from June $18^{th}$ 2015 to June $22^{nd}$, 2015. Standard Solution No.2 (0.153 uU/mL) and No.5 (4.96 uU/mL) was selected as the two-point standards for the TSH test, and Standard Solution No.3 (0.777 ng/dL) and No.4 (2.044 ng/dL) was selected as the two-point standards for the FT4 test. 38 test samples were subject to correlation analysis. Results For TSH, the result of the normal test shows ranges of 0.20 ~ 0.37 uU/mL for Control1, 0.53 ~ 0.71 uU/mL for Control2, and 6.77 ~ 7.94uU/mL for Control3, while the result of two-point calibration curve test shows ranges of 0.18 ~ 0.27 uU/mL for Control1, 0.53 ~ 0.71 uU/mL for Control2, and 7.30 ~ 8.52 uU/mL for Control3. For FT4, the result of the normal test shows ranges of 0.85 ~ 0.94 ng/dL for Control1 and 4.23 ~ 4.57 ng/dL for Control2, while the result of two-point calibration curve test shows ranges of 0.61 ~ 0.75 ng/dL for Control1 and 3.88 ~ 5.71 ng/dL for Control2. For TSH, the CV% of the normal test for Control1, Control2 and Control3 are 10.5, 3.3 and 3.6 respectively, while the CV% of the two-point calibration curve test for Control1 and Control1 are 12.4, 8.2 and 5.1 respectively. The result shows an outstanding correlation of TSH: y = 0.9985x - 0.0459 $R^2=0.9986$. For FT4, the CV% of the normal test for Control1 and Control2 are 0.70 and 0.71 respectively, while the CV% of the two-point calibration curve test for Control1 and Control1 are 8.7 and 16.2 respectively. The result shows an outstanding correlation of FT4: y = 1.2674x - 0.1133 $R^2=0.9824$. Conclusion The two-point calibration curve can be efficiently applied for TSH in cases where the number of test samples is not large, since the number of samples to be re-tested increases when the result is abnormal from the calibration curve. The two-point calibration curve test should not be applied for FT4 where the results do not consistently comply with the quality assessment range. Depending on how the two-point calibration curve is applied, up to 5 test tubes can be conserved per test, and the reduced time for reagent dispensing is anticipated to have a positive effect on the TAT (turnaround time).

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.2
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• pp.21-26
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• 2016

Purpose Because of many advantages, PET-CT Scanners generally use CT Data for attenuation correction. By using CT based attenuation correction, we can get anatomical information, reduce scan time and make more accurate correction of attenuation. However in case metal artifact occurred during CT scan, CT-based attenuation correction can induce artifacts and quantitative errors that can affect the PET images. Therefore this study infers true SUV of metal artifact region from attenuation corrected image count -to- non attenuation corrected image count ratio. Materials and Methods Micro phantom inserted $^{18}F-FDG$ 4mCi was used for phantom test and Biograph mCT S(40) is used for medical test equipment. We generated metal artifact in micro phantom by using metal. Then we acquired both metal artifact region of correction factor and non metal artifact region of correction factor by using attenuation correction image count -to- non attenuation correction image count ratio. In case of clinical image, we reconstructed both attenuation corrected images and non attenuation corrected images of 10 normal patient($66{\pm}15age$) who examined PET-CT scan in SNUH. After that, we standardize several organs of correction factor by using attenuation corrected image count -to- non attenuation corrected count ratio. Then we figured out metal artifact region of correction factor by using metal artifact region of attenuation corrected image count -to- non attenuation corrected count ratio And we compared standard organs correction factor with metal artifact region correction factor. Results according to phantom test results, metal artifact induce overestimation of correction factor so metal artifact region of correction factors are 12% bigger than the non metal artifact region of correction factors. in case of clinical test, correction factor of organs with high CT number(>1000) is $8{\pm}0.5%$, correction factor of organs with CT number similar to soft tissue is $6{\pm}2%$ and correction factor of organs with low CT number(-100>) is $3{\pm}1%$. Also metal artifact correction factors are 20% bigger than soft tissue correction factors which didn't happened metal artifact. Conclusion metal artifact lead to overestimation of attenuation coefficient. because of that, SUV of metal artifact region is overestimated. Thus for more accurate quantitative evaluation, using attenuation correction image count -to-non attenuation correction image count ratio is one of the methods to reduce metal artifact affect.

• Childhood Kidney Diseases
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• v.4 no.1
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• pp.63-68
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• 2000

Purpose: MCDK is regarded as a common cause of abdominal masses in children. And the presentation of the MCDK is usually a unilateral flank mass in the a newborn. Bialteral disease results in either fetal demise or necessity fer renal replacement therapy at birth. This study is designed to assess the clinical features and natural history of the unilateral multicystic dysplastic kidney. Patients and Methods: From January 1987 to January 2000 data were obtained retrospectively on 57 patients (28 boys and 29 girls, age ranged 1day-11years) who had a diagnosis of multicystic dysplastic kidney. The diagnosis of multicystic dysplastic kidney was confirmed by a combination of ultrasonography and radionuclide scan. Voiding cystourethrogram study in 31 patients were done to determine the condition of the contalateral kidney. Restllts: $84\%$ of the patients were diagnosed before birth by antenatal ultrasonography Clinical manifestations of children with postnatal diagnoses were palpable abdominal mass($3.5\%$), abdominal distension($17\%$), and incidental($10.5\%$). The abnormalities in contralateral kidney were hydronephrosis($21\%$), compensatory hypertrophy($12\%$), simple cyst($2\%$), bifid pelvis($2\%$). Surgical management was performed in 20 patients($35\%$) due to recurrent infection, for diagnostic purpose to differentiate from malignancy and abdominal distention. Follow-up in the remaining 37 patients continued (mean 18 months) and results of sonogram findings were involution change in 23 patients($40\%$) and no interval changes in 13 patient($23\%$). Conclusions : The apparent tendency to regression of the dysplastic kidney and no difference in the number of complications justify a conservative management rather than operative intervention except in associated severe complications such as urinary tract infection or rupture of cysts.