• Korean Journal of Radiology
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• 제21권8호
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• pp.1018-1023
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• 2020

The coronavirus disease (COVID-19) outbreak has reached global pandemic status as announced by the World Health Organization, which currently recommends reverse transcription polymerase chain reaction (RT-PCR) as the standard diagnostic tool. However, although the RT-PCR test results may be found negative, there are cases that are found positive for COVID-19 pneumonia on computed tomography (CT) scan. CT is also useful in assessing the severity of COVID-19 pneumonia. When clinicians desire a CT scan of a patient with COVID-19 to monitor treatment response, a safe method for patient transport is necessary. To address the engagement of medical resources necessary to transport a patient with COVID-19, our institution has implemented the use of mobile CT. Therefore, we report two cases of COVID-19 pneumonia evaluated by using mobile cone-beam CT. Although mobile cone-beam CT had some limitations regarding its image quality such as scatter noise, motion and streak artifacts, and limited field of view compared with conventional multi-detector CT, both cases had acceptable image quality to establish the diagnosis of COVID-19 pneumonia. We report the usefulness of mobile cone-beam CT in patients with COVID-19 pneumonia.

• 구강회복응용과학지
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• 제26권2호
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• pp.111-120
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• 2010

목적: 본 연구는 측두하악관절의 시상 CT 이미지에서 최대교두감합위시 양 과두의 위치와 대칭성을 평가하기 위해 기획되었다. 재료 및 방법: Cone-bem CT가 각 100명의 남/녀 그리고 증상/무증상으로 분류된 총 200명의 400개 측두하악관절을 평가하는데 사용되었다. 3명의 독립된 평가자(치과의사)가 전방위(AP), 중앙위(MP), 후방위(PP)으로 분류된 과두 위치와 양 과두의 대칭성을 결정하였다. 결과: 성별에 따른 전방위, 중앙위, 후방위의 평균 퍼센트(%)는 남성에서 48.5, 28.5, 23였고, 여성에서 34, 38, 28였다. 과두의 대칭성은 성별에 관계없이 대칭인 경우가 많았다. 증상과 무증상의 관점에서 보면 전방위, 중앙위, 후방위의 평균 퍼센트(%)는 무증상 그룹에서 44.5, 34, 21.5였고, 증상이 있는 그룹에서는 37, 33.5, 29.5였다. 과두의 대칭성은 무증상 그룹에서는 대칭성이 더 빈번했고, 증상 그룹에서는 비대칭이 더 많았다. 결론: 이 데이터는 Cone-bean CT에 의해서 얻어진 최대교두감합위에서 과두 위치의 임상 평가를 위해 유용한 기준이 될 수 있을 것으로 사료된다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제35권1호
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• pp.21-25
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• 2009

Objective: The purpose of this study is to determine the prevalence of sinus disease and abnormalities in patients scheduled for dental implant in maxillary posterior area using cone beam CT. Patients and Method: One hundred five maxillary sinuses in eighty-seven patients who underwent cone beam CT for dental implant in maxillary posterior area were included. Any patients who had previous history of sinus operations were not included. The sinus abnormalities were classified as follows ; normal (membrane thickness <2 mm), mucosal thickening (membrane thickness ${\geq}$ 2 mm and < 6 mm), partial opacification (membrane thickness > 6 mm but not full), full opacification and mucous retention cyst. The relationship between the remaining bone height, sinus symptoms and maxillary sinus abnormality was statistically surveyed. Results: Of 105 maxillary sinuses in 87 patients, 80 (76%) maxillary sinuses showed abnormalities ; 4 of 4 symptomatic patients and 76 of 101 asymptomatic patients. Mucosal thickening was the most common sinus abnormality. Only 3 (4%) of 80 maxillary sinus abnormalities were caused by the odontogenic origin. The prevalence of maxillary sinus abnormalities was higher in the symptomatic group than asymptomatic one (p<0.05). Conclusion: Maxillary sinus abnormalities were very common in the patients who were planning implantation in maxillary posterior areas. This result supports that thorough evaluation for maxillary sinus is recommended when implant treatment is planned for those areas.

• 대한방사선치료학회지
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• 제24권1호
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• pp.15-21
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• 2012

목 적: 본원에서 시행하고 있는 영상유도 방사선치료(Image Guided Radiation Therapy, IGRT)는 On-Board Imager system(OBI)을 이용하여 실시하고 있다. 본 논문에서는 Cone-Beam CT에서 물질 및 호흡의 변화가 영상에 미치는 영향을 분석하고 평가하고자 한다. 대상 및 방법: 호흡의 모양을 임의로 조정할 수 있는 구동 팬텀(Motion Phantom)을 이용하여 기준 호흡에 따른 주기, 진폭, 기저호흡(Baseline)을 변화시키면서 폐 등가 물질 내의 지름 3 cm인 구 형태의 아크릴(Acryl)과 임상에 이용되고 있는 표지자(Fiducial Marker) 두 물질에 대하여 Cone-Beam CT를 총 3회 획득하고, 분석하였다. 결 과: 첫 번째 물질의 종류에 따라 구동 팬텀의 동일한 움직임을 원형 아크릴(Arcyl)일 때 100%, 표지자일 때 120% 나타내었다. 두 번째 기준 호흡 변화에 따라 기준 호흡의 영상크기를 1로 상쇄(Offset)하면 원형 아크릴(Arcyl)의 경우 기저호흡(Baseline)을 1.8 mm 이동 시켰을 때 1.13, 3.3 mm 이동 시켰을 때 1.27, 주기가 1초일 때 1.01, 2.5초일 때 1.045, 진폭이 기준의 0.7배일 때 0.86, 1.7배일 때 1.43의 변화를 보였고, 표지자의 경우 Baseline 1.8 mm shift일 때 1.18, 3.3 mm shift일 때 1.34, 주기가 1초일 때 1.0, 2.5초일 때 1.0, 진폭이 기준의 0.7배일 때 0.99, 1.7배일 때 1.66의 변화를 보였다. 결 론: Cone-Beam CT는 물질에 따라 그 움직임을 나타내는 것에 Fiducial marker의 경우 영상 크기에 20%의 영향이 있었다. 호흡의 변화에 따른 영향은 아크릴(Arcyl)의 경우 최소 13% 최대 43%, Fiducial marker의 경우 최소 18% 최대 66%의 변화를 보였다. 이런 영상의 차이는 큰 불확실성 요인이므로 Cone-Beam CT 획득 전에 환자의 호흡을 안정화해야 한다. 또한 영상획득 중간에도 지속적인 환자의 호흡 관찰을 하여 환자의 큰 호흡변화를 관찰하였다면 영상유도 후에 반드시 투시를 이용하여 치료부위를 확인할 필요가 있으며 재 Cone-Beam CT 획득을 통하여 보다 정확한 영상유도를 하는 것이 바람직하다고 사료된다.

• 한국음향학회지
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• 제28권2호
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• pp.141-147
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• 2009

본 논문에서는 인체에 유해한 방사능 피폭량이 부챗살 형태의 Fan Beam 보다 상대적으로 적은 원추형 Cone Beam CT 시스템을 사용하여 3차원 영상을 빠르게 구성하기 위한 회전 기반법 알고리즘을 제안하였다. 그리고 계산 속도를 빠르게 하기 위하여 초월함수가 더 적은 3단계 회전 행렬을 이용하여 3차원 영상을 구현하였다. 또한 본 연구에서 구성한 영상을 일반적으로 사용되는 라돈 변환 알고리즘으로 구현된 3차원 영상과 비교하여 영상의 질은 평균적으로 단면 영상 당 10% 정도의 오차를 보이며 미약하게 저하되었으나 영상 구성 속도 면에서는 35배 개선됨을 보였다. 이는 대략 초당 $4{\sim}5$ 프레임을 얻을 수 있는 수치이며 간단한 구조를 가진 피사체라면 보다 많은 프레임을 얻을 수 있어 3차원 동영상을 실시간으로 구현할 수 있는 가능성을 보였다.

• Korean Journal of Radiology
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• 제22권7호
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• pp.1203-1212
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• 2021

Objective: To investigate the diagnostic accuracy and complications of cone-beam CT-guided percutaneous transthoracic needle biopsy (PTNB) of juxtaphrenic lesions and identify the risk factors for diagnostic failure and complications. Materials and Methods: In total, 336 PTNB procedures for lung lesions (mean size ± standard deviation [SD], 4.3 ± 2.3 cm) abutting the diaphragm in 326 patients (189 male and 137 female; mean age ± SD, 65.2 ± 11.4 years) performed between January 2010 and December 2014 were included. The accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the PTNB procedures for the diagnosis of malignancy were measured based on the intention-to-diagnose principle. The risk factors for diagnostic failures and complications were evaluated using logistic regression analysis. Results: The accuracy, sensitivity, specificity, PPV, and NPV were 92.7% (293/316), 91.3% (219/240), 91.4% (74/81), 96.9% (219/226), and 77.9% (74/95), respectively. There were 23 diagnostic failures (7.3%), and lesion sizes ≤ 2 cm (p = 0.045) were the only significant risk factors for diagnostic failure. Complications occurred in 98 cases (29.2%), including 89 cases of pneumothorax (26.5%) and 7 cases of hemoptysis (2.1%). The multivariable analysis showed that old age (> 65 years) (p = 0.002), lesion size of ≤ 2 cm (p = 0.003), emphysema (p = 0.006), and distance from the pleura to the target lesion (> 2 cm) (p = 0.010) were significant risk factors for complications. Conclusion: The diagnostic accuracy of cone-beam CT-guided PTNB of juxtaphrenic lesions for malignancy was fairly high, and the target lesion size was the only significant predictor of diagnostic failure. Complications of cone-beam CT-guided PTNB of juxtaphrenic lesions occurred at a reasonable rate.

• 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.

• 대한치과의사협회지
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• 제53권12호
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• pp.967-974
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• 2015

Purpose: This study was performed to investigate the characteristics of mandibular incisive canal (MIC) in Korean population. Materials and methods: A total of 97 subjects (60 males and 37 females) who underwent cone-beam computed tomography were included in the study. The anatomic features of MIC was assessed according to gender. Length, diameter and distance to inferior, lingual and buccal border were measured at the origin and the terminal. Also the distribution of MIC at each tooth position was evaluated. Results: Of 97 patients included, 75(77.3%) presented bilateral MIC and 13(13.4%) presented unilateral MIC. Of 194 hamimandibles, MIC was detected in 102(85%) sites in male and 61(82.4%) sites in female. Gender and side showed no statistically significant differences in detectability. The length, diameter and distance to adjacent structures were bigger in male than in female except the distance to lingual border. MIC travelled anteriorly in a slightly downward and lingual direction and usually terminated between the first premolar and the canine. On cross-sectional view, MIC showed individually scattered distribution both buccolingually and superoinferiorly. Conclusion: MIC is well detected with cone-beam computed tomography. Considered that the length and the location of MIC has large variations between individuals, its localization using cone-beam CT is highly recommended before performing surgical procedures such as implant placement and bone harvesting.

• Asian Pacific Journal of Cancer Prevention
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• 제14권3호
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• pp.1649-1654
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• 2013

Objective: This work aimed to evaluate the safety and clinical efficacy of transcatheter arterial chemoembolization (TACE) combined with c-arm cone-beam CT guided synchronous radiofrequency ablation (RFA) in treatment of large hepatocellular carcinoma (HCC). Methods: 21 patients with large HCC were studied from January 2010 to March 2012. TACE combined with synchronous C-arm cone-beam CT guided RFA were performed on a total of 25 lesions. Conventional imaging examination (CEUS, enhanced CT or MRI) and AFP detection were regularly conducted to evaluate the technical success rate of combined treatment, complications, treatment response, time without disease recurrence and survival rate. Results: The technical success rate of combined treatment was 100%, without any significant complication. After 1 month, there were 19 cases with complete response and 2 cases with partial response, with an complete response rate of 90.4% (19/21) and a clinical effective rate of 100% (21/21). The complete response rates of single nodular lesions (100%, 17/17) was significantly higher than that of multiple nodular lesions (50%, 2/4) (P<0. 05). During 2 to 28 months of follow-up, in 19 cases with complete response, the average time without disease recurrence was $10.8{\pm}6$ months. The total survival rates of 6, 12 and 18 months in 21 patients were 100%, respectively. Conclusion: TACE combined with synchronous C-arm CT guided RFA is safe and effective for treatment of large HCC. The treatment efficacy for single nodular lesion is better than that for multiple nodular lesions.

• 한국방사선학회논문지
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• 제9권7호
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• pp.433-438
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• 2015

치과방사선 검사에 있어 방사선작업종사자의 위치에 따라 방사선 노출 정도를 평가하고자 촬영실과 납유리, 조작대에서 방사선량률을 측정하였다. 사용된 장치로는 Standard(Max-GLS, Shinhung), 파노라마(PCH-2500, Vatech), 세팔로(PCH-2500), Cone beam CT(PHT-30LFO, Vatech)이며, 방사선측정기는 PM1405 장비이다. 촬영조건은 임상에서 사용하는 인자와 동일하게 설정하였다. 그 결과 촬영실 안에서는 Cone beam CT가 98 uSv/h로 가장 높았으며, standard가 0.4 uSv/h로 가장 낮은 수치를 보였다. 또 파노라마가 촬영방식이 다름으로 인하여 세팔로 보다 높게 측정되었다. 납유리 표면과 조작대에서는 구강내와 파노라마, 세팔로는 모두 기록준위 이하로 측정되었지만, Cone beam CT는 누설선량이 있는 것으로 측정되었다. 이에 방사선작업종사는 적절한 방호도구를 하고 촬영시간을 최대한 줄여야 한다. 또, 방사선실의 구조 또한 효율적으로 설계해야 할 것이다. 치과방사선검사는 최근 지속적으로 증가하고 있기 때문에 환자와 방사선작업종사자에 대한 적절한 방호 대책이 필요하다.