• 한국콘텐츠학회논문지
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• 제7권7호
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• pp.114-123
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• 2007

전산화단층촬영(CT)은 영상의학에서 매우 유용한 검사의 진단법으로 적절한 정도관리에 의한 영상의 평가가 필요하다. CT의 정도관리 항목에서 영상의 질을 결정하는 중요한 요소를 위해 AAPM CT 팬텀으로 영상검사를 수행하였다. 정도관리 평가항목은 "특수의료장비의 설치 및 운영에 관한 규칙"에서 정한 기준으로 물의 CT 감약계수, 노이즈, 균일도, 공간분해능, 대조도 분해능, 절편 두께, 인공물 존재 유무를 평가하였다. 획득한 영상은 규칙의 합격기준에 충족하였다. CT 영상의 질을 최적으로 유지하기 위해서는 지속적으로 팬텀 및 임상검사를 통해 영상의 질을 평가하기 위해 정도관리를 시행하여야 한다.

• Journal of Radiation Protection and Research
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• 제40권1호
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• pp.17-24
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• 2015

To improve accuracy of dose calculation on kilovoltage cone beam computed tomography (kV CBCT) images, a custom-made phantom was fabricated to acquire an accurate CT number to electron density curve by full scatter of cone beam x-ray. To evaluate the dosimetric accuracy, 9 volumetric modulated arc therapy (VMAT) plans for head and neck (HN) cancer and 9 VMAT plans for lung cancer were generated with an anthropomorphic phantom. Both CT and CBCT images of the anthropomorphic phantom were acquired and dose-volumetric parameters on the CT images with CT density curve (CTCT), CBCT images with CT density curve ($CBCT_{CT}$) and CBCT images with CBCT density curve ($CBCT_{CBCT}$) were calculated for each VMAT plan. The differences between $CT_{CT}$ vs. $CBCT_{CT}$ were similar to those between $CT_{CT}$ vs. $CBCT_{CBCT}$ for HN VMAT plans. However, the differences between $CT_{CT}$ vs. $CBCT_{CT}$ were larger than those between $CT_{CT}$ vs. $CBCT_{CBCT}$ for lung VMAT plans. Especially, the differences in $D_{98%}$ and $D_{95%}$ of lung target volume were statistically significant (4.7% vs. 0.8% with p = 0.033 for $D_{98%}$ and 4.8% vs. 0.5% with p = 0.030 for $D_{95%}$). In order to calculate dose distributions accurately on the CBCT images, CBCT density curve generated with full scatter condition should be used especially for dose calculations in the region of large inhomogeneity.

• 대한두개안면성형외과학회지
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• 제18권2호
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• pp.128-131
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• 2017

With advances in diagnostic technology, radiologic diagnostic methods have been used more frequently, and physical examination may be neglected. The authors report a case of pediatric medial orbital trapdoor fracture in which the surgery was delayed because computed tomography (CT) findings did not indicate bone displacement, incarceration of rectus muscle, or soft tissue herniation. A healthy 6-year-old boy was admitted to the emergency room for right eyebrow laceration. We could not check eyeball movement or diplopia, because the patient was irritable. Thus, we performed facial CT under sedation, but there was normal CT finding. Seven days later, the patient visited our hospital due to persistent nausea and dizziness. We were able to perform a physical examination this time. Lateral gaze of right eye was limited. CT still did not show any findings suggestive of fracture, but we decided to perform exploratory surgery. We performed exploration, and found no bone displacement, but discovered entrapped soft tissue. We returned the soft tissue to its original position. The patient fully recovered six weeks later. To enable early detection and treatment, thorough physical examination and CT reading are especially needed when the patient shows poor compliance, and frequent follow-up observations are also necessary.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2005년도 가을 학술발표논문집 Vol.32 No.2 (2)
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• pp.859-861
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• 2005

X-ray를 이용한 CT(Computed Tomography : 이하 CT)영상은 사물에 대해 회전하면서 X-ray가 투과하여 감약 정도에 따라서 영상을 획득하지만 검사 목적과는 관계없이 발생되는 통계적인 오차로 인해 정확한 CT영상의 구성을 교란하거나 방해하여 영상의 질을 저하시키고 미세 부분의 관찰 능력을 감소시키는 장해 음영인 아티팩트(artifact)라는 노이즈가 발생한다. 이러한 노이즈를 제거하는 필터를 설계 할 때는 두 가지 고려해야 할 사항이 있는데 첫째는 영상내의 노이즈을 정확히 판단하여 효과적으로 제거해야 하며, 둘째로는 원래의 영상에 가깝도록 경계와 같은 세부 영역을 보존해야 한다는 점이다. 기존에는 mean 필터나 median 필터, 그리고 Gaussian 필터 등을 사용했지만 상세한 부분을 보존하기에는 실패하는 단점이 있다. 따라서 본문에서는 wavelet 변환을 하여 영상의 주파수 대역을 저주파 영역과 고주파 영역으로 분리하여 각각의 영역에서 노이즈를 제거할 수 있도록 적합한 필터를 설계하고 방법을 제안하여 그 필터를 CT 3차원 뇌혈관 영상에 적용하여 많은 노이즈를 제거하였고 낮은 Threshold값에서도 작은 혈관을 관찰 할 수 있었다.

• Journal of Gastric Cancer
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• 제10권4호
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• pp.188-195
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• 2010

Purpose: This study was done to evaluate the usefulness of preoperative computed tomography (CT) and intraoperative laparoscopic ultrasound to facilitate treatment of gastric submucosal tumors. Materials and Methods: The feasibility of laparoscopic wedge resection as determined by CT findings of tumor size, location, and growth pattern was correlated with surgical findings in 89 consecutive operations. The role of laparoscopic ultrasound for tumor localization was analyzed. Results: Twenty-three patients were considered unsuitable for laparoscopic wedge resection because of large tumor size (N=13) or involvement of the gastroesophageal junction (N=9) or pyloric channel (N=1). Laparoscopic wedge resection was not attempted in 11 of these patients because of large tumor size. Laparoscopic wedge resection was successfully performed in 65 of 66 (98.5%) patients considered suitable for this procedure. Incorrect interpretation of preoperative CT resulted in a change of surgery type in seven patients (7.9%): incorrect CT diagnosis on gastroesophageal junction involvement (N=6) and on growth pattern (N=1). In 18 patients without an exophytic growth pattern, laparoscopic ultrasound was necessary and successfully localized all lesions. Conclusions: Preoperative CT and laparoscopic ultrasound are useful for surgical planning and tumor localization in laparoscopic wedge resection.

• 대한디지털의료영상학회논문지
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• 제5권1호
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• pp.78-84
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• 2002

To evaluate the relative time required to perform a CT(computed tomography) examination in a filmless versus a film-based system and helical versus nonhelical studies. Time and Motion studies were performed in 175 consecutive CT examinations. Images from 85 examinations were electronically transferred to a PACS, and 90 were printed to film. The time required to obtain and electronically transfer the images or print the images to film and make the current and previous studies available to the radiologists for interpretation was recorded. The time required for a radiological technologist to complete a CT examination was reduced by 43% with the PACS compared with the film-based system and nonhelical was reduced 10-20% with helical studies. This reduction was due to the elimination of a transfer and printing, such as the printing at window or level settings. The use of PACS can result in the elimination of time tasks for the radiological technologist, resulting in marked reduction in examination time. This reduction can result in decreased cost and increased productivity in PACS operation.

• 한국임상수의학회지
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• 제40권2호
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• pp.139-146
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• 2023

Three dogs were referred with epistaxis and facial deformity. Computed tomography (CT) scan identified masses in the bilateral nasal cavity with soft tissue attenuation and contrast enhancement. These masses had caused adjacent bones lysis, especially lysis of cribriform plate that extended to the intracranial region. Base on histopathology and CT imaging results, tumors were diagnosed as nasal carcinomas at stage 4. Three dogs were treated with stereotactic radiation therapy (SRT). These dogs received 30-35 Gy from 3-5 daily treatments (7-10 Gy per treatment). The sizes of tumors decreased the most on follow-up CT images at one month after treatment. Recurrence was confirmed between 3 and 5 months after completing SRT. The survival time of dogs treated with SRT were 110, 190, and 210 days, respectively. This study confirmed that SRT could treat canine nasal carcinomas with cribriform plate lysis without causing serious radiation toxicities. Follow-up CT examination is considered at 1 month and 3 to 6 months after SRT to accurately evaluate the prognosis and the timing of recurrence.

• Radiation Oncology Journal
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• 제35권2호
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• pp.180-184
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• 2017

Patients with locally advanced lung cancer and very limited pulmonary function (forced expiratory volume in 1 second $[FEV1]{\leq}1L$) have dismal prognosis and undergo palliative treatment or best supportive care. We describe two cases of locally advanced node-positive non-small cell lung cancer (NSCLC) patients with very limited lung function treated with induction chemotherapy and moderate hypofractionated image-guided radiotherapy (Hypo-IGRT). Hypo-IGRT was delivered to a total dose of 45 Gy to the primary tumor and involved lymph nodes. Planning was based on positron emission tomography-computed tomography (PET/CT) and four-dimensional computed tomography (4D-CT). Internal target volume (ITV) was defined as the overlap of gross tumor volume delineated on 10 phases of 4D-CT. ITV to planning target volume margin was 5 mm in all directions. Both patients showed good clinical and radiological response. No relevant toxicity was documented. Hypo-IGRT is feasible treatment option in locally advanced node-positive NSCLC patients with very limited lung function ($FEV1{\leq}1L$).

• Journal of Gastric Cancer
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• 제11권4호
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• pp.234-238
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• 2011

A 67 year old male at a regular checkup underwent esophagogastroduodenoscopy. On performing esophagogastroduodenoscopy, a lesion about 1.2 cm depressed was noted at the gastric angle. The pathology of the biopsy specimen revealed a well-differentiated adenocarcinoma. On performing an abdominal computed tomography (CT) scan & positron emission tomography-computed tomography (PET-CT) scan, no definite evidence of gastric wall thickening or mass lesion was found. However, lymph node enlargement was found in the left gastric and prepancreatic spaces. This patient underwent laparoscopic assisted distal gastrectomy and D2 lymph node dissection. On final examination, it was found out that the tumor had invaded the mucosal layer. The lymph node was a metastasized large cell neuroendocrine carcinoma with an unknown primary site. The patient refused chemotherapy. He opted to undergo a close followup. At the postoperative month 27, he had a focal hypermetabolic lesion in the left lobe of the liver that suggested metastasis on PET-CT scan. He refused to undergo an operation. He underwent a radiofrequency ablation.

• Tuberculosis and Respiratory Diseases
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• 제69권2호
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• pp.129-133
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• 2010

Extramedullary plasmacytoma (EMP) is a rare disorder that typically occurs in the upper airway. Although the condition rarely arises in the lungs, a few cases have been reported. Here, we report a case of pulmonary plasmacytoma in 66-year-old man, who had been treated with VAD (vincrestine, adriamycin, dexamethasone) chemotherapy for multiple myeloma. The patient had been declared clear of multiple myeloma after 4 cycles of chemotherapy. Three months later, the patient had multiple masses visible on computed tomography (CT) and on positron emission tomography-computed tomography (PET-CT) with hot uptake. Subsequent studies using CT-guided needle biopsy and immunohistochemical stain showed pulmonary plasmacytoma. Bone marrow biopsy, serum, and urine M protein tests were repeated, showing no evidence of multiple myeloma. Pulmonary plasmacytomas, as extramedullary plasmacytomas, were considered an isolated manifestation of multiple myeloma recurrence. We treated the patient with concurrent chemoradiotherapy and the pulmonary plasmacytomas regressed dramatically.