• Radiation Oncology Journal
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• v.27 no.1
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• pp.42-48
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• 2009

Purpose: The introduction of image guided radiation therapy/four-dimensional radiation therapy (IGRT/4DRT) potentially increases the accumulated dose to patients from imaging and verification processes as compared to conventional practice. It is therefore essential to investigate the level of the imaging dose to patients when IGRT/4DRT devices are installed. The imaging dose level was monitored and was compared with the use of pre-IGRT practice. Materials and Methods: A four-dimensional CT (4DCT) unit (GE, Ultra Light Speed 16), a simulator (Varian Acuity) and Varian IX unit with an on-board imager (OBI) and cone beam CT (CBCT) were installed. The surface doses to a RANDO phantom (The Phantom Laboratory, Salem, NY USA) were measured with the newly installed devices and with pre-existing devices including a single slice CT scanner (GE, Light Speed), a simulator (Varian Ximatron) and L-gram linear accelerator (Varian, 2100C Linac). The surface doses were measured using thermo luminescent dosimeters (TLDs) at eight sites-the brain, eye, thyroid, chest, abdomen, ovary, prostate and pelvis. Results: Compared to imaging with the use of single slice non-gated CT, the use of 4DCT imaging increased the dose to the chest and abdomen approximately ten-fold ($1.74{\pm}0.34$ cGy versus $23.23{\pm}3.67$cGy). Imaging doses with the use of the Acuity simulator were smaller than doses with the use of the Ximatron simulator, which were $0.91{\pm}0.89$ cGy versus $6.77{\pm}3.56$ cGy, respectively. The dose with the use of the electronic portal imaging device (EPID; Varian IX unit) was approximately 50% of the dose with the use of the L-gram linear accelerator ($1.83{\pm}0.36$ cGy versus $3.80{\pm}1.67$ cGy). The dose from the OBI for fluoroscopy and low-dose mode CBCT were $0.97{\pm}0.34$ cGy and $2.3{\pm}0.67$ cGy, respectively. Conclusion: The use of 4DCT is the major source of an increase of the radiation (imaging) dose to patients. OBI and CBCT doses were small, but the accumulated dose associated with everyday verification need to be considered.

• Journal of Chest Surgery
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• v.32 no.10
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• pp.910-915
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• 1999

Background: Positron emission tomography(PEFT) using fluorine-18 deoxyglucose(FDG), showing increased FDG uptake and retention in malignant cells, has been proven to be useful in differentiating malignant from benign tissues. We indertook the prospective study to compare the accuracy of the whole-body FDG PET with that of the conventional chest computed tomography(CT) for nodal staging of non-small-cell lung cancers(NSCLC). Material and Method: FDG PET and contrast enhanced CT were performed in 36 patients with potentially resectable NSCLC. Each Imaging study was evaluated independently, and nodal stations were localized according to the AJCC regional lymph nodes mapping system. Extensive lymph node dissection(1101 nodes) of ipsi- and contralateral mediastinal nodal stations was performed at thoracotomy and/or mediastinoscopy. Image findings were compared with the histopathologic staging results and were analyzed with the McNema test(p) and Kappa value(k). Result: The sensitivity, specificity, positive predictive value, and negative predictive value of CT for ipsilateral mediastinal nodal staging were 38%, 68%, 25%, 79%, and 61%, and those of PET were 88%, 71%, 47%, 95%, and 75%(p>0.05, K=0.29). When analyzed by individual nodal group(superior, aortopulmonary window, and inferior), the sensitivity, specificity, positive predictive value, and negative predictive value of CT were 27%, 82%, 22%, 85%, and 73%, and those of PET were 60%, 87%, 92%, and 82%(p<0.05, k=0.27). Conclusion: FDG PET in addition to CT appears to be superior to CT alone for mediastinal staging of non-small cell lung cancers.

• Korean Journal of Artificial Intelligence
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• v.9 no.2
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• pp.1-5
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• 2021

Although CT has an advantage in describing the three-dimensional anatomical structure of the human body, it also has a disadvantage in that high doses are exposed to the patient. Recently, a deep learning-based image reconstruction method has been used to reduce patient dose. The purpose of this study is to analyze the dose reduction and image quality improvement of deep learning-based reconstruction (DLR) on the adult's chest CT examination. Adult lung phantom was used for image acquisition and analysis. Lung phantom was scanned at ultra-low-dose (ULD), low-dose (LD), and standard dose (SD) modes, and images were reconstructed using FBP (Filtered back projection), IR (Iterative reconstruction), DLR (Deep learning reconstruction) algorithms. Image quality variations with respect to varying imaging doses were evaluated using noise and SNR. At ULD mode, the noise of the DLR image was reduced by 62.42% compared to the FBP image, and at SD mode, the SNR of the DLR image was increased by 159.60% compared to the SNR of the FBP image. Based on this study, it is anticipated that the DLR will not only substantially reduce the chest CT dose but also drastic improvement of the image quality.

• Korean Journal of Radiology
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• v.21 no.10
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• pp.1138-1149
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• 2020

Coronavirus disease 2019 (COVID-19) is a transmissible respiratory disease that was initially reported in Wuhan, China in December 2019. With the alarming levels of COVID-19 spread worldwide, the World Health Organization characterized COVID-19 as a pandemic. Over the past several months, chest CT has played a vital role in early identification, disease severity assessment, and dynamic disease course monitoring of COVID-19. The published data has enriched our knowledge on the etiology, epidemiology, clinical manifestations, and pathologic findings of COVID-19. Additionally, as the imaging spectrum of the disease continues to be defined, extrapulmonary infections or other complications will require further attention. This review aims to provide an updated framework and essential knowledge with which radiologists can better understand COVID-19.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.619-625
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• 2022

In the field of imaging medicine, computed tomography is one of the most common test methods and one of the most frequently used test methods in hospitals. However, it is accompanied by a very high radiation exposure compared to other test methods. In order to reduce exposure, CT scans should be performed only when absolutely necessary, and even if the tests are performed because they are absolutely necessary, a protocol that serves the purpose of the test and allows the test to be performed in a small dose should be used. In this study, we wanted to learn about the most up-to-date radiation dose usage information used by the region's leading general hospitals and develop a diagnostic reference level (DRL). In the experimental results, the Head CT and Abdomen CT tests showed that DLP was higher than the NRPB (U.K) and Korean DRL. The DLP values used by Chest CT were low for all 3 types of CT devices. The hospital found that efforts to reduce exposure should be made during CT examinations, and in particular, Head CT and Abdomen CT determined that efforts to reduce exposure were necessary.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.6
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• pp.582-587
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• 2009

A 59-year-old woman who was diagnosed with malignant pheochromocytoma underwent $^{18}F$-fluorodeoxyglucose positron emission tomography/computed tomography ($^{18}F$-FDG PET/CT). She had undergone left adrenalectomy for pheochromocytoma 4 years previously. Recent multiple metastatic pulmonary nodules were noted on the chest X-ray. After treatment with $^{131}I$-metaiodobenzylguanidine ($^{131}I$-MIBG) with 7.4 GBq, post-therapy $^{131}I$-MIBG scintigraphy depicted multiple distant metastases including lung, liver, abdominal para-aortic and mesenteric lymph nodes. $^{18}F$-FDG PET/CT also depicted multiple metastases in lung, liver, and abdominal para-aortic lymph nodes, but some lesions were not shown. In this case, $^{131}I$-MIBG scintigraphy found additional lesions in metastatic malignant pheochromocytoma.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.6
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• pp.35-43
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• 2009

In the Computer Aided Diagnosis(CAD) System, the efficient way of classifying nodules from chest CT images of a patient is to perform the classification of the remaining part after the pulmonary vessel extraction. During the pulmonary vessel extraction, due to the small difference between the vessel and nodule features in imaging studies such as CT scans after having an injection of contrast, nodule maybe extracted along with the pulmonary vessel. Therefore, the pulmonary vessel extraction method plays an important role in the nodule classification process. In this paper, we propose a nodule reclassification method based on vessel thickness analysis. The proposed method consist of four steps, lung region searching step, vessel extraction and thinning step, vessel topology formation and correction step and the reclassification of nodule in the vessel candidate step. The radiologists helped us to compare the accuracy of the CAD system using the proposed method and the accuracy of general one. Experimental results show that the proposed method can extract pulmonary vessels and reclassify false-positive nodules accurately.

• Tuberculosis and Respiratory Diseases
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• v.53 no.1
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• pp.66-70
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• 2002

Pulmonary Sequestration is a rare congenital malformation during embryouic development which results in a cystic mass of nonfunctioning lung tissue. A diagnosis of a pulmonary sequestration has traditionally relied upon identifying the pathological arterial vessels by arteriography, computed tomography, and magnetic resonance imaging. We reported a case of pulmonary sequestration diagnosed by Doppler sonography and subsequent CT angiography. A 21-year-old-woman admitted to hospital for an investigation of recurrent pneumonia with left lower chest pain. A doppler ultrasound sonography showed an aberrant blood supply from the descending thoracic aorta to the left lower chest lesion. The pulmonary sequestration was confirmed by the subsequent CT angiograph.

• Tuberculosis and Respiratory Diseases
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• v.68 no.5
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• pp.298-300
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• 2010

Diaphragmatic paralysis can be demonstrated through diaphragmatic elevation on chest X-ray after thoracic lung surgery or the placement of chest tubing. Additional causes of diaphragmatic paralysis are iatrogenic, mass, atelectasis, etc. For the diagnosis of diaphragmatic paralysis, it required some studies (fluoroscopy, computed tomography [CT], magnetic resonance imaging). Diaphragmatic hernia of the liver is a rare clinical entity, usually found after trauma in adults. Congenital diaphragmatic hernia in neonates requires surgery. Non-traumatic diaphragmatic hernia of the liver in an adult is a rare right-sided diaphragmatic hernia. On developing any symptoms, surgery must be performed. When diaphragmatic hernia is incidentally found in adults without trauma, it is placed under observation for a time period. We diagnosed the diaphragmatic herniation of a right hepatic lobe by 16-slice CT scan without surgery.

• Tuberculosis and Respiratory Diseases
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• v.78 no.2
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• pp.112-119
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• 2015

Primary thymic adenocarcinoma is a very rare malignancy of the anterior mediastinum with no standardized treatment. A 36-year-old male patient presented with hoarseness over the past 3 months. A chest computed tomography (CT) scan showed an infiltrative mass to the proximal vessels and aortic arch in left upper mediastinum ($4.1{\times}3.1{\times}5.4cm$). Brain magnetic resonance imaging (MRI) showed focal lesions, suggesting metastasis in the left frontal lobe. A thoracoscopic biopsy of the mediastinal mass confirmed a primary thymic adenocarcinoma forming a glandular structure with atypia of tumor cells. The patient received four cycles of systemic chemotherapy, consisting of etoposide and cisplatin, with concurrent radiotherapy (6,000 cGy/30 fractions) to the mediastinal lesion and the metastatic brain lesion (4,200 cGy/12 fractions). A follow-up chest CT scan and brain MRI showed a decrease in the size of the left upper mediastinal mass and brain lesion. We report a rare case of the primary thymic adenocarcinoma with a literature review.