• The Korean Journal of Nuclear Medicine
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• v.32 no.2
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• pp.143-150
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• 1998

Purpose: T1-201 SPECT has been used in differentiating benign and malignant pulmonary lesions. While its sensitivity may be high, the specificity and predictive values are reported to be variable depending on the type of benign lung lesion. The purpose of this study was to prospectively assess the efficacy of T1-201 SPECT for differentiating benign and malignant single pulmonary lesion in a population with a high prevalence of benign pulmonary lesion, especially, tuberculosis. Materials and Methods: One-hundred thirty-three patients, having 89 malignant and 44 benign lesions(23 active tuberculosis, 5 inactive tuberculosis, 3 aspergil-loma, 3 focal pneumonia, 2 thymoma, and 8 others), were imaged using a dual-headed system at 15 minute(early) and 3 hour (delayed) following administration of 111MBq T1-201. The images were read visually and lesion-to-background ratios(L/B) were obtained from transverse tomographic slices. Retention index was expressed as [(delayed L/B- early L/B) $\div$ early L/B]. Results: 82/89(92%) and 83/89(93%) of the malignant lesions were visually positive on the early and delayed images, and 27/44(61%) and 26/44(59%) of the benign lesions were also visually positive on both images. Although a statistically significant difference was found between the mean L/B's of the malignant and benign lesions, L/B was not useful for differentiating the two due to a large overlap. There was no difference in retention indices. Conclusion: Despite of its high sensitivity, the specificity of T1-201 SPECT was unacceptably low in patients with active benign lesions. The positive and negative predictive values for lung cancer in a population with a high prevalence of the benign single pulmonary lesion was only marginal.

• Journal of radiological science and technology
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• v.31 no.4
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• pp.389-399
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• 2008

Corrections of attenuation, scatter and resolution are important in order to improve the accuracy of single photon emission computed tomography (SPECT) image reconstruction. Especially, the heart movement by respiration and beating cause the errors in the corrections. Myocardial phantom is used to verify the correction methods, but there are many different parts in the current phantoms in actual human body. Therefore the results using a phantom are often considered apart from the clinical data. We developed a new phantom that implements the human body structure around the thorax more faithfully. The new phantom has the small mediastinum which can simulate the structure in which the lung adjoins anterior, lateral and apex of myocardium. The container was made of acrylic and water-equivalent material was used for mediastinum. In addition, solidified polyurethane foam in epoxy resin was used for lung. Five different sizes of myocardium were developed for the quantitative gated SPECT (QGS). The septa of all different cardiac phantoms were designed so that they can be located at the same position. The proposed phantom was attached with liver and gallbladder, the adjustment was respectively possible for the height of them. The volumes of five cardiac ventricles were 150.0, 137.3, 83.1, 42.7 and 38.6ml respectively. The SPECT were performed for the new phantom, and the differences between the images were examined after the correction methods were applied. The three-dimensional tomography of myocardium was well reconstructed, and the subjective evaluations were done to show the difference among the various corrections. We developed the new cardiac and torso phantom, and the difference of various corrections was shown on SPECT images and QGS results.

• Radiation Oncology Journal
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• v.25 no.1
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• pp.26-33
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• 2007

[ $\underline{Purpose}$ ]: The aim of this study is to evaluate and compare the incidence and aspects of myocardial perfusion defects in patients who were subjected to either two-dimensional or three-dimensional simulation techniques for early left-sided breast cancer. The myocardial perfusion defects were determined from using single photon emitted computerized tomography (SPECT) myocardial perfusion images. $\underline{Materials\;and\;Methods}$: Between January 2002 and August 2003, 32 patients were enrolled in this study. The patients were diagnosed as having early (AJCC stage T1-T2N0M0) left-sided breast cancer and were treated with tangential irradiation after breast-conserving surgery and systemic chemotherapy. The patients were divided into two groups according to the type of simulation received: two-dimensional simulation using an X-ray fluoroscope simulator or three-dimensional simulation with a CT simulator. All patients underwent technetium-99m-sestamibi gated perfusion SPECT at least 3 years after radiotherapy. The incidence and area of myocardial perfusion defects were evaluated and were compared in the two groups, and at the same time left ventricular ejection fraction and cardiac wall motion were also analyzed. The cardiac volume included in the radiation fields was calculated and evaluated to check for a correlation between the amount of irradiated cardiac volume and aspects of myocardial perfusion defects. $\underline{Results}$: A myocardial perfusion defect was detected in 11 of 32 patients (34.4%). There were 7 (46.7%) perfusion defect cases in 15 patients who underwent the two-dimensional simulation technique and 4 (23.5%) patients with perfusion defects in the three-dimensional simulation group (p=0.0312). In 10 of 11 patients who had myocardial perfusion changes, the perfusion defects were observed in the cardiac apex. The left ventricular ejection fraction was within the normal range and cardiac wall motion was normal in all patients. The irradiated cardiac volume of patients in the three-dimensional simulation group was less than that of patients who received the two-dimensional simulation technique, but there was no statistical significance as compared to the incidence of perfusion defects. $\underline{Conclusion}$: Radiotherapy with a CT simulator (three-dimensional simulation technique) for early left-sided breast cancer may reduce the size of the irradiated cardiac volume and the incidence of myocardial perfusion defects. Further investigation and a longer follow-up duration are needed to analyze the relationship between myocardial perfusion defects and clinical ischemic heart disease.

• The Journal of the Korea Contents Association
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• v.17 no.6
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• pp.81-85
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• 2017

The aim of this study was to evaluate the usability of applied Low dose Computed Tomography(LDCT) protocol in examining urinary calculus using computed tomography. The subjects of this study were urological patients who visited a medical institution located in Busan from June to December 2016 and the protocol used in this study was Adaptive Statistical Iterative Reconstruction: low-dose CT with 50% Adaptive Statistical Iterative Reconstruction (ASIR). As results of quantitative analysis, the mean pixel value and standard deviation within kidney region of image(ROI)of the axial image were $26.21{\pm}7.08$ in abdomen CT pre scan and $20.03{\pm}8.16$ in low-dose CT. Also the mean pixel value and standard deviation within kidney ROI of the coronal image were $22.07{\pm}7.35$ in abdomen CT pre scan and $21.67{\pm}6.11$ in low dose CT. The results of qualitative analysis showed that four raters' mean values of observed kidney artifacts were $19.14{\pm}0.36$ when using abdomen CT protocol and $19.17{\pm}0.43$ in low-dose CT, and the mean value of resolution and contrast was $19.35{\pm}0.70$ when using abdomen CT protocol and $19.29{\pm}0.58$ in low-dose CT. Also the results of a exposure dose analysis showed that the mean values of CTDIvol and DLP in abdomen CT pre scan were 18.02 mGy and $887.51mGy{\cdot}cm$ respectively and the mean values of CTDIvol and DLP when using low-dose CT protocol were 7.412 mGy and $361.22mGy{\cdot}cm$ respectively. The resulting dose reduction rate was 58.82% and 59.29%, respectively.

• Radiation Oncology Journal
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• v.27 no.2
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• pp.55-63
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• 2009

Purpose: This study was performed to objectively evaluate the rate of tumor response to hypofractionated radiotherapy for advanced squamous cell carcinomas of the head and neck. Materials and Methods: Thirty-one patients with advanced squamous cell carcinoma of the head and neck, who were treated by hypofractionated radiotherapy with 3 Gy per fraction for palliative purpose between 1998 and 2008, were reviewed retrospectively. Every tumor-volume was measured and evaluated from CT (computed tomography) images obtained before and 2~3 months after radiotherapy. The radiation toxicity was assessed during and after radiotherapy. A statistical analysis was performed to investigate overall survival, progressionfree survival, and the prognostic factors for survival and response. Results: The median age of the study patients was 70 years. In addition, 85% of the patients were in stage 4 cancer and 66.7% had an ECOG performance status of 1~2. The mean tumor-volume was 128.4 cc. Radiotherapy was administered with a total dose of 24~45 Gy (median: 36 Gy) over 10~25 days. Twenty-nine patients were treated with 30 Gy or more. The observed complete response rate was 12.9% and the partial response rate was 61.3%. Median survival time was 8.9 months and the 1-year progression-free survival rate was 12.9%. The treatment response rate was confirmed as a prognostic factor in the rate of survival. The primary site, stage, tumor-volume, radiotherapy field and overall radiation-dose showed a significant relationship with survival and treatment response. No grade 4 toxicity was observed during and after radiotherapy. Conclusion: There was an objective tumor-regression in about 74% of patients treated by hypofractionated radiotherapy. Further evaluation is needed to select the appropriate fraction-size and patient who may require the additional radiotherapy.

• Korean Journal of Dental Materials
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• v.44 no.2
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• pp.187-195
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• 2017

TheraCal LC, a new light-cured, resin-modified calcium silicate-filled base/liner material, has been introduced as a pulpotomy agent. The aim of this study was to evaluate the capacity of hard tissue formation and pulpal response after pulpotomy with TheraCal LC. Twenty-two 9-week-old male rats were anesthetized, cavities were prepared in maxillary first molars and pulps were capped with formocresol (FC), mineral trioxide aggregate (MTA), and TheraCal LC. Specimens obtained from rats were scanned using a high-resolution micro CT system. The specimens were prepared and evaluated histologically, and immunofluorescence assay was performed to assess the dentin matrix protein-1 (DMP-1) expression. On micro CT analysis, the MTA and TheraCal LC groups showed thicker hard tissue formation than the FC group. On hematoxylin and eosin (H&E) staining, MTA and TheraCal LC groups showed dentine bridge formation with vital pulp beneath the materials. On immunofluorescence analysis, DMP-1 was highly expressed in the TheraCal LC group compared to the FC group. TheraCal LC showed similar capacity to form hard tissue as MTA when it was used as a pulpotomy agent. Because of its good manipulation and faster setting time compared to MTA, TheraCal LC could be considered as a good alternative to MTA.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.24-30
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• 2009

Purpose: Today, Prostate cancer has been gradually increasing, according to the change of internal incidence rate of cancer. Generally, prostate cancer has lead to dead over 90%, in case of metastasis of lymph node and bone. So, innovative development of new radiopharmaceutical and imaging modality is progressed for detection of that metastasis, in nuclear medicine, now. Therefore, this study shows the usefulness of $^{18}F$-Fluoride PET/CT improved diagnosability on bone metastasis of prostate cancer. Materials and Methods: In this study, 33 male patients with prostate cancer were examined (The mean age: $67.8{\pm}10.2$ years old). Every patient was done each whole body bone scan (WBBS) and $^{18}F$-Fluoride positron emission tomography/computed tomography ($^{18}F$-Fluoride PET/CT). And then, using Receiver Operating Characteristic Curve (ROC curve), each sensitivity and specificity of two modalities was measured and compared with. Results: In 22 patients (66.6%) of all, bone metastasis was detected. And, in WBBS, sensitivity was 63.6%, specificity, 81.8%; in $^{18}F$-Fluoride PET/CT, sensitivity was 100% and specificity was 90.9%. As a result of ROC curve, AUROC (The Area under an ROC) of WBBS was 0.778, and that of $^{18}F$-Fluoride PET/CT, 0.942. Conclusions: $^{18}F$-Fluoride PET/CT was higher both sensitivity and specificity than WBBS, and it was valuable to detect bone metastasis of prostate cancer more definitely, with 3D imaging realization. Also, in $^{18}F$-Fluoride PET/CT, physiological images were acquired in more short time than WBBS, so, it was possible to reduce patient's waiting time and complaint. Therefore, it is considered that $^{18}F$-Fluoride PET/CT is able to improve diagnosability by offering more accurate images, as cuts in a share of high cost.

• The Korean Journal of Nuclear Medicine Technology
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• v.23 no.2
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• pp.38-42
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• 2019

Purpose Although computed tomography (CT) is used for coronary artery calcification, it is difficult to differentiate between high risk microcalcifications. Studies have shown that $^{18}F$-sodium fluoride ($^{18}F-NaF$) is very useful for the diagnosis of microcalcifications. In this study, we aimed to evaluate the usefulness of $^{18}F-NaF$ PET imaging in quantitative evaluation of calcification. Materials and Methods A total of 45 patients ($67.1{\pm}6.9years\;old$) were injected with 250 MBq of $^{18}F-NaF$ for 1 hour and images were acquired for 30 minutes. All patients underwent CT angiography (CTAngiography, CTA) before the PET scan. The SUVmax of calcification was measured and the background radioactivity of the left atrium was measured to determine Target to Background (TBR) and quantitatively analyzed. High risk group was classified through ROC curve (Receiver Operating Characteristic Curve). Results There were 226 coronary artery calcifications in the cohort and SUVmax was $1.15{\pm}0.39$. Of the 28 patients (62%), 58 were classified as high risk (TBR > 1.25). The remaining 168 were $TBR{\leq}1.25$. Conclusion $^{18}F-NaF$ PET images were available for quantitative assessment of microcalcifications and could be classified into high-risk groups. The combination of angiographic CT and $^{18}F-NaF$ PET may be a new method for early diagnosis of high-risk microcalcifications.

• The korean journal of orthodontics
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• v.35 no.6 s.113
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• pp.409-419
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• 2005

Studies for diagnostic analysis using three-dimensional (3D) CT images are recently in progress and needs for 3D craniofacial analysis are increasing in the fields of orthodontics. It is especially essential to analyze the facial soft tissue after orthodontic treatment and orthognathic surgery. In this study 3D CT images of adults with normal occlusion were taken to analyze the facial soft tissue. Norms were obtained from CT images of adults with normal occlusion (12 males, 11 females) using a computer program named V works 4.0 program. 3D coordinate planes were established using soft tissue Nasion as the reference point and a total of 20 reproducible landmarks of facial soft tissue were obtained using the multiple reconstructive sectional images (axial, sagittal and coronal images) of the V works 4.0 program: soft tissue Nasion, Pronasale, Subnasale, Upper lip center, Lower lip center, soft tissue B, soft tissue Pogonion, soft tissue Menton, Endocanthion (Rt/Lt), Alare lateralis (Rt/Lt), Cheilion (Rt/Lt), soft tissue Gonion (Rt/Lt), Tragus (Rt/Lt), and Zygomatic point (Rt/Lt). According to the established landmarks and measuring method, the 3D CT images of adults with normal occlusion were measured and the normal positional measurements and their Net (${\delta}=\sqrt{{X^2}+{Y^2}+{Z^2}}$) values were obtained using V surgery program, In the linear measurement between landmarks, there was a significant difference between males and females except Na' -Sn and En(Rt)-En(Lt). The normal ranges of Na'-Zy, Na'-Ch and Na'-Go' (facial depth) were obtained, which was difficult to measure by two-dimensional (2D) cephalometric analysis and facial photographs. These data may be used as references for 3D diagnosis and treatment planning for patients with malocclusion and dentofacial deformity.

• Radiation Oncology Journal
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• v.28 no.4
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• pp.238-248
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• 2010

Purpose: To compare the dose distributions between three-dimensional (3D) and four-dimensional (4D) radiation treatment plans calculated by Ray-tracing or the Monte Carlo algorithm, and to highlight the difference of dose calculation between two algorithms for lung heterogeneity correction in lung cancers. Materials and Methods: Prospectively gated 4D CTs in seven patients were obtained with a Brilliance CT64-Channel scanner along with a respiratory bellows gating device. After 4D treatment planning with the Ray Tracing algorithm in Multiplan 3.5.1, a CyberKnife stereotactic radiotherapy planning system, 3D Ray Tracing, 3D and 4D Monte Carlo dose calculations were performed under the same beam conditions (same number, directions, monitor units of beams). The 3D plan was performed in a primary CT image setting corresponding to middle phase expiration (50%). Relative dose coverage, D95 of gross tumor volume and planning target volume, maximum doses of tumor, and the spinal cord were compared for each plan, taking into consideration the tumor location. Results: According to the Monte Carlo calculations, mean tumor volume coverage of the 4D plans was 4.4% higher than the 3D plans when tumors were located in the lower lobes of the lung, but were 4.6% lower when tumors were located in the upper lobes of the lung. Similarly, the D95 of 4D plans was 4.8% higher than 3D plans when tumors were located in the lower lobes of lung, but was 1.7% lower when tumors were located in the upper lobes of lung. This tendency was also observed at the maximum dose of the spinal cord. Lastly, a 30% reduction in the PTV volume coverage was observed for the Monte Carlo calculation compared with the Ray-tracing calculation. Conclusion: 3D and 4D robotic radiotherapy treatment plans for lung cancers were compared according to a dosimetric viewpoint for a tumor and the spinal cord. The difference of tumor dose distributions between 3D and 4D treatment plans was only significant when large tumor movement and deformation was suspected. Therefore, 4D treatment planning is only necessary for large tumor motion and deformation. However, a Monte Carlo calculation is always necessary, independent of tumor motion in the lung.