• Journal of Biomedical Engineering Research
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• v.31 no.4
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• pp.259-268
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• 2010

Breast cancer is the most prevalent woman cancer, and its prevalence rate is increasing rapidly. It is necessary to develop the breast-dedicated positron emission tomography (PET) or positron emission mammography (PEM) systems with high resolution and sensitivity to improve the accuracy of diagnosis of breast cancer. Therefore, it is necessary to develop the high-end PET system technologies, such as the measurement of depth-of-interaction (DOI) and fully digitalized data acquisition, to establish high performance breast imaging systems. In this paper, recent technical advances in breast-dedicated PET imaging systems will be reviewed.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.313-318
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• 2019

To improve the sensitivity, a detector using a block scintillator was developed. In the pixelated scintillator, a reflector is located between pixels to move the light generated from the scintillator to the photosensor as much as possible, and sensitivity loss occurs in the reflector portion. In order to improve the sensitivity and to have the characteristics of the pixelated scintillator, the block scintillator was processed into a scintillator in pixel form through three-dimensional laser engraving. The energy spectra and energy resolution of each pixel were measured, and sensitivity analysis of block and pixel scintillator was performed through GATE simulation. The measured global energy resolution was 20.7%, and the sensitivity was 18.5% higher than that of the pixel scintillator. When this detector is applied to imaging devices such as gamma camera and positron emission tomography, it will be possible to shorten the imaging time and reduce the dose of patient by using less radiation source.

• Journal of radiological science and technology
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• v.36 no.4
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• pp.305-311
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• 2013

The purpose of this study was to evaluate the Pathological Diagnosis associated with pSUV uptake of $^{18}F$-FDG PET/CT. We had enrolled 39 women that underwent $^{18}F$-FDG PET/CT before operative. We evaluated whether there was correlation between the pSUV of $^{18}F$-FDG PET/CT and prognostic factors. As a results, pSUV level increase according to tumor size but pSUV had no significant association with tumor size. pSUV of high histologic grade was higher than low histologic grade, and pSUV showed positive correlations with histologic grade. The ER and PR showed significant negative correlations with the pSUV of $^{18}F$-FDG PET/CT. Therefore, our results demonstrated that an correlation exists between pSUV and prognostic factors such as histologic grade, ER and PR.

• Annals of Clinical Neurophysiology
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• v.1 no.1
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• pp.26-30
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• 1999

Background : The origin of P300 was still on debate nbut thought to be in the frontal, temporal or parietal lobe. As the transcranial doppler ultrasonography(TCD) gives us and opportunity to observe hemodynamic chaged dynamically and the middle cerebral artery feeds these ares of the hemisphere, we observed the change of mean flow velocity of MCA during the event related potential test(ERP) to determine the role of these structures in P300 generation. Method : Twenty normal subjects(male : 13, age : 24-29 years) performed ERP. An auditory oddball pardigm was used to elicit the ERPs. TCD examination was performed with 2-MHz probe monitoring the left MCA(Transscan, EME). After signal identification and adjustments to maximize the Doppler signal strength, the probe was mechanically locked during the monitoring. The changes of blood flow velocity of the left middle cerebral artery(MCA) induced by cognitive demands were monitored. The measurement of the meal flow velocities(MFV) of MCA were made while the subjects were prior to, during, and after ERP. We recorded the MFVs during ERP. Statistical analysis was performed using t-tests with SPSS-PC for windows release 6.0. Results : All subjects showed a relative increase in MFV of MCA during the task. The mean rise was about 3.2-4.2%(p <0.05). Although TCD does not measure absolute values of regional cerebral blood flow(rCBF) or absolute rCBF changes, changes of flow velocity can reflect relative rCBF changes. Conclusions : The generation site of P300 still remains unclear but the neocortical, thalamic and limbic region and temporal-parietal cortex have been proposed. The MCA supplies these anatomical structures. The Changes of flow veolocity of MCA during the ERP test suggest that the some part of the brain fed y the MCA activate of the temporal lobe or parietal lobes, we can deduce that some parts of brain fed by the MCA participate in the generation of P300.

• Investigative Magnetic Resonance Imaging
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• v.12 no.2
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• pp.89-99
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• 2008

Imaging assessment of prostate cancer is one of the most difficult sections of oncology imaging. Detecting, localizing and staging of the primary prostate cancer by preoperative imaging are still challenging for the radiologist. Magnetic resonance (MR) imaging provides excellent soft tissue contrast and is widely used for solid organ imaging, but results of preoperative imaging of the prostate gland with conventional MR imaging is unsatisfactory. Positron emission tomography and computed tomography (PET/CT) is the cornerstone in oncology imaging, but some limitations prohibit the assessment of primary prostate cancer with PET or PET/CT. Recent studies to overcome these insufficient accuracies of imaging evaluation of primary prostate cancers with advanced MR techniques and PET and PET/CT are reported. In this article, we review the imaging findings of prostate cancer on variable modalities, focused on MR imaging and PET/CT.

• Journal of KIISE:Software and Applications
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• v.32 no.7
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• pp.612-624
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• 2005

In this paper, we propose a surface-based registration using a gaussian weighted distance map for PET-CT brain image fusion. Our method is composed of three main steps: the extraction of feature points, the generation of gaussian weighted distance map, and the measure of similarities based on weight. First, we segment head using the inverse region growing and remove noise segmented with head using region growing-based labeling in PET and CT images, respectively. And then, we extract the feature points of the head using sharpening filter. Second, a gaussian weighted distance map is generated from the feature points in CT images. Thus it leads feature points to robustly converge on the optimal location in a large geometrical displacement. Third, weight-based cross-correlation searches for the optimal location using a gaussian weighted distance map of CT images corresponding to the feature points extracted from PET images. In our experiment, we generate software phantom dataset for evaluating accuracy and robustness of our method, and use clinical dataset for computation time and visual inspection. The accuracy test is performed by evaluating root-mean-square-error using arbitrary transformed software phantom dataset. The robustness test is evaluated whether weight-based cross-correlation achieves maximum at optimal location in software phantom dataset with a large geometrical displacement and noise. Experimental results showed that our method gives more accuracy and robust convergence than the conventional surface-based registration.

• Journal of radiological science and technology
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• v.45 no.3
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• pp.241-248
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• 2022

In this study, a recovery coefficient (RC) calculation was conducted that can correct the underestimation of the standardized uptake value (SUV) due to the partial volume effect (PVE) through phantom measurements and formulas. The experiment was conducted using a dynamic phantom capable of implement cranio-caudal movement at a respiratory rate of 15 times per minute along with the measured phantom experiment of the stopped state, and the RC of the moving state is calculated and compared. Ingenuity TF (Philips Healthcare, Netherland) was used as a positron emission tomography/computed tomography (PET/CT) device. PET-CT Phantom (Biodex Medical System, USA) was used as a phantom for measurement. A phantom image in a stationary state was acquired, and a moving phantom image was acquired using the AZ-733V Respiratory Phantom (Anzai Medical Co, Japan) capable of breathing movement in the cranio-caudal direction under the same acquisition parameters. For RC calculation, the sphere maximum radioactivity concentration and the background mean radioactivity concentration of the acquired images were measured, and the initially determined sphere and background radioactivity concentrations were calculated. The calculated RC was 0.08 to 0.72. The size of sphere smaller, it was confirmed that the RC reduced. And the RC in the moving state reduced than in the stationary state. As a result of this study, the change of the RC was confirmed according to the size of spheres and the phantom moving. Using the RC derived by implement movement of breathing with the respiratory phantom, it is possible to considering correction of underestimated SUV by the partial volume effect of PET images and the patient movements.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.93-99
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• 2010

Purpose: Currently, PET/CT scan has been known to provide useful information to both preoperative and postoperative examination of cancer patients. Contracted stomach by the long fasting could cause difficulties of interpretation because of its size on reconstructed image data. To solve this problem, after the whole body PET/CT scan, patients were administrated in drinking 300 mL of water to expand stomach and performed additional scan on stomach region. Not only PET/CT scan but also CT performs this water-administration, and patients were take oral solution to make stomach expand for stomach cancer. When this scan performed, patients lay supine position. In this study, we evaluated the capacity of stomach through PET/CT scan with drinking water performed in supine and prone position so that we can distinguish exact location of cancer around pylorus and inferior wall of stomach. Furthermore, image data from supine and prone positions were analyzed the difference of volume of stomach through the change of standardized uptake values. Materials and Methods: From July 2009 to January 2010 in severance hospital, 30 patients who were diagnosed as early gastric cancer or advanced gastric cancer were chosen. All patients had PET/CT scan before the operation and have had follow-up PET/CT. The patients fast for at least 8 hours, and had an injection intravenously with $^{18}F$-FDG, 7.4 MBq (0.2 mCi/kg) per kilogram. They were rested for 60 minutes. Before the examination, all patients were administrated to drink water for 300 mL Patients had PET/CT scan with supine position around the region of stomach, whole body, and around the region of stomach with prone position after drinking another 300 mL of water respectively. Results: As a results of comparison between stomach capacity of 30 patients in supine and prone position, the study draw results that average capacity of stomach body was 460.29 $mm^2$ in supine position, and 641.39 $mm^2$ in prone position for 30 patients. The change of capacity shows 41.3% expanded in prone position. And there was no noticeable difference at maximum standardized uptake values in supine position and prone position. Conclusion: As results, stomach would have more expanded capacity in prone position than supine position. For patients who have physical disabilities to move freely, additional scan in prone position will be obstacle to perform. However, if additional scan in supine position add with the scan in prone position, it will be easier to diagnose stomach cancer. Moreover, we believe that this study will help the research for inventing support tools for patients who have physical disabilities in prone position.

• The Korean Journal of Nuclear Medicine Technology
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• v.21 no.2
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• pp.74-79
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• 2017

Purpose Proton therapy can deliver an optimal dose to tumor while reducing unnecessary dose to normal tissue as compared the conventional photon therapy. As proton beams are irradiated into tissue, various positron emitters are produced via nuclear fragmentation reactions. These positron emitters could be used for the dose verification by using PET. However, the short half-life of the radioisotopes makes it hard to obtain the enough amounts of events. The aim of this study is to investigate the effect of off-line PET imaging scan time on the PET image quality. Materials and Methods The various diameters of spheres (D=37, 28, 22 mm) filled with distilled water were inserted in a 2001 IEC body phantom. Then proton beams (100 MU) were irradiated into the center of the each sphere using the wobbling technique with the gantry angle of $0^{\circ}$. The modulation widths of the spread out bragg peak were 16.4, 14.7 and 9.3 cm for the spheres of 37, 28 and 22 mm in diameters respectively. After 5 min of the proton irradiation, the PET images of the IEC body phantom were obtained for 50 min. The PET images with different time courses (0-10 min, 11-20 min, 21-30 min, 31-40 min and 41-50 min) were obtained by dividing the frame with a duration of 10 min. In order to evaluate the off-line PET image quality with the different time courses, the contrast-to-noise ratio (CNR) of the PET image calculated for each sphere. Results The CNRs of the sphere (D=37 mm) were 0.43, 0.42, 0.40, 0.31 and 0.21 for the time courses of 0-10 min, 11-20 min, 21-30 min, 31-40 min and 41-50 min respectively. The CNRs of the sphere (D=28 mm) were 0.36, 0.32, 0.27, 0.19 and 0.09 for the time courses of 0-10 min, 11-20 min, 21-30 min, 31-40 min and 41-50 min respectively. The CNR of 37 mm sphere was decreased rapidly after 30 min of the proton irradiation. In case of the spheres of 28 mm and 22 mm, the CNR was decreased drastically after 20 min of the irradiation. Conclusion The off-line PET imaging time is an important factor for the monitoring of the proton therapy. In case of the lesion diameter of 22 mm, the off-line PET image should be obtained within 25 min after the proton irradiation. When it comes to small size of tumor, the long PET imaging time will be beneficial for the proton therapy treatment monitoring.

• The Journal of the Korean bone and joint tumor society
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• v.18 no.2
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• pp.78-82
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• 2012

Purpose: Interferon-${\alpha}2b$ using immunotherapy of malignant melanoma is known to increase the microscopic enemies that remain after surgical resection of the tumor to prevent recurrence, disease-free survival and overall survival. Authors in patients with malignant melanoma after surgical resection and high-dose interferon-${\alpha}$ immunotherapy treated group of disease-free survival and overall survival compared with the results of the treatment of immune therapy to a preliminary report. Materials and Methods: From February 2010 to October 2012 at our institution between being diagnosed with malignant melanoma after surgical immunotherapy treated patients were analyzed. Patients was evaluated using the stage AJCC stage IIA 3 cases, IIB 1 cases, IV 1 were as follows. Follow-up period of at least 7 months, and a maximum of 32 months. As maintenance therapy after the first induction therapy group underwent immunotherapy interferon-${\alpha}$ of body-surface area per 200,000 IU five times in a week for 4 weeks sedentary and body surface area a total of 48 weeks per week to 100,000 IU three times subcutaneously. These patients for local recurrence and metastases, and distant metastasis were investigated disease-free survival was investigated. Results: Interferon-evaluation through follow-up chest computed tomography (CT) and positron emission computed tomography (PET CT) in patients who underwent the ${\alpha}$ immunotherapy results above both local recurrence and metastases without evidence of distant metastases. Conclusion: The high-dose ${\alpha}2b$ immunotherapy performed in patients to prevent the local recurrence of the tumor and metastasis to the current or future ultimate survival and disease-free survival improvement achieved is additional study and follow-up will be needed.