• 대한치과교정학회지
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• 제42권6호
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• pp.329-334
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• 2012

Objectives: To determine the prevalence of incidental maxillary sinus findings in a large sample of orthodontic patients by cone-beam computed tomography (CBCT) with a wide field of view and assess the relationships of such abnormalities with age and gender. Methods: Five hundred thirteen CBCT scans obtained for orthodontic diagnosis and treatment planning in a Northern Italian population (N = 513; 292 female and 221 male subjects; 1,026 maxillary sinuses) were studied. The frequencies of pseudocysts and mucosal thickening of the maxillary sinus were recorded. Logistic regression analysis was used to determine the influence of age and gender on these abnormalities. Results: Pseudocysts were detected in 52 patients (10.1%) and 59 sinuses (5.75%). Mucosal thickening was observed in 206 patients (40.1%) and 258 sinuses (25.1%). Gender and age were significantly associated with pseudocysts (p = 0.027) and mucosal thickening (p < 0.001), respectively. Conclusions: Half of the orthodontic patients had incidental maxillary sinus findings. Men were more likely to show pseudocysts, and older patients (aged 41 - 60 years) were more likely to show mucosal thickening.

• Imaging Science in Dentistry
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• 제50권2호
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• pp.93-98
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• 2020

Purpose: Little is known regarding the accuracy of clinical magnetic resonance imaging (MRI) protocols with acceptable scan times in sinus graft assessment. The aim of this study was to evaluate the correlations between MRI and cone-beam computed tomographic (CBCT) measurements of maxillary sinus grafts using 2 different clinical MRI imaging protocols. Materials and Methods: A total of 15 patients who underwent unilateral sinus lift surgery with biphasic calcium phosphate were included in this study. CBCT, T1-weighted MRI, and T2-weighted MRI scans were taken 6 months after sinus lift surgery. Linear measurements of the maximum height and buccolingual width in coronal images, as well as the maximum anteroposterior depth in sagittal images, were performed by 2 trained observers using CBCT and MRI Digital Imaging and Communication in Medicine files. Micro-computed tomography (micro-CT) was also performed to confirm the presence of bone tissue in the grafted area. Correlations between MRI and CBCT measurements were assessed with the Pearson test. Results: Significant correlations between CBCT and MRI were found for sinus graft height (T1-weighted, r=0.711 and P<0.05; T2-weighted, r=0.713 and P<0.05), buccolingual width (T1-weighted, r=0.892 and P<0.05; T2-weighted, r=0.956 and P<0.05), and anteroposterior depth (T1-weighted, r=0.731 and P<0.05; T2-weighted, r=0.873 and P<0.05). The presence of bone tissue in the grafted areas was confirmed via micro-CT. Conclusion: Both MRI pulse sequences tested can be used for sinus graft measurements, as strong correlations with CBCT were found. However, correlations between T2-weighted MRI and CBCT were slightly higher than those between T1-weighted MRI and CBCT.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권5호
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• pp.311-319
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• 2012

Purpose: The aim of this study is to evaluate the vertical changes of the lip and perioral soft tissue, following orthognathic surgery in skeletal class III patients by a cephalometric analysis of a cone beam computed tomography (CBCT). Methods: A total of 20 skeletal class III patients, who had bimaxillary surgery with Le Fort 1 osteotomy and bilateral sagittal split ramus osteotomy, were included in this study. The surgical plan for maxilla was posterosuperior impaction with the anterior nasal spine, as the rotation center. Further, the surgical plan for mandible was also posterosuperior movement. The soft tissue changes between lateral cephalogram and CBCT were compared. And the correlations between independent variables and dependent variables were evaluated. Results: There were no significant differences of the soft tissues changes between lateral cephalogram and CBCT. Upper lip philtrum length (SnLs), nasolabial angle increased and upper lip vermilion length (LsStms), lower lip length (StmiB'), lower lip vermilion length (StmiLi), lower lip philtrum length (LiB') and soft tissue lower facial height (SnMe') decreased after surgery. Change of SnLs (${\Delta}$SnLs) was influenced by vertical change of menton (${\Delta}$MeV), and change of LsStms (${\Delta}$LsStms) was influenced by upper lip thickness (ULT). Change of StmiLi' (${\Delta}$StmiLi') were influenced by preoperative overjet. Change of StmiB' (${\Delta}$StmiB') were influenced by preoperative overjet, vertical change of lower incisor (${\Delta}$L1V) and horizontal change of posterior nasal spine (${\Delta}$PNSH). Change of LiB' (${\Delta}$LiB') was influenced by ${\Delta}$L1V and ${\Delta}$PNSH. Change of SnMe' (${\Delta}$SnMe') was influenced by ${\Delta}$MeV, horizontal change of upper incisor (${\Delta}$U1H) and horizontal change of lower incisor (${\Delta}$L1H). ${\Delta}$Nasolabial angle was influenced by change of ULT (${\Delta}$ULT). Conclusion: Both soft tissues and hard tissues can be evaluated by CBCT. Posterosuperior rotation of maxillomandibular complex resulted in increase of upper lip philtrum length and nasolabial angle, while the upper lip vermilion length, lower lip philtrum length, lower lip vermilion length, and soft tissue lower facial height showed a decrease.

• 대한치과보철학회지
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• 제58권2호
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• pp.95-102
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• 2020

목적: Cone-beam computed tomographic (CBCT)를 이용하여 한국인의 상악 제1대구치(MM1), 제2대구치(MM2)에서 제2근심협측(MB2) 근관, 치근 융합 및 C형 근관의 발생률에 대해 평가하였다. 재료 및 방법: 술 전 평가를 위해 CBCT 촬영을 한 환자를 선택했다. 1658명의 환자로부터 1498개의 MM1과 1742개의 MM2의 CBCT 영상이 획득되었고, MB2 근관, 치근융합 및 C형 근관을 분석했다. 연령, 성별 및 치아위치와 MB2 근관 발생률간의 관계도 조사하였다. 결과: 연구표본은 비교적 고령(평균연령: 66.1세)이었다. MB2 근관의 발생률은 MM1, MM2 각각 60.1%, 28.0% 였고, MM1, MM2에서 각각 Weine Type III, Type II가 우세했다. 연령이 증가함에 따라 MB2 근관은 감소하는 경향을 보였으며, MM1에서는 남성에서 MB2 근관이 더 많이 발견되었다. 치근융합은 MM1에서 2.3%, MM2에서 26.2%, C형 근관은 MM1에서 0.4%, MM2에서 2.7%로 모두 MM2에서 발생률이 더 높았다. 결론: MB2 근관은 MM2보다 MM1에서 더 발생률이 높았다. 치근융합과 C형 근관은 모두 MM2에서 더 발생률이 높았다.

• Imaging Science in Dentistry
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• 제41권4호
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• pp.143-150
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• 2011

Purpose : The aim of this study was to compare the diagnostic accuracy of cone-beam computed tomography (CBCT) images and bitewing images in detection of secondary caries. Materials and Methods : One hundred and twenty proximal slots of Class II cavities were randomly prepared on human premolar and molar teeth, and restored with amalgam (n=60) and composite resin (n=60). Then, artificial secondary caries lesions were randomly created using round steel No. 4 bur. The teeth were radiographed with a conventional bitewing technique and two CBCT systems; Pax-500ECT and Promax 3D. All images were evaluated by five observers. The area under the receiver operating characteristic (ROC) curve ($A_z$) was used to evaluate the diagnostic accuracy. Significant difference was tested using the Friedman test (p value<0.05). Results : The mean $A_z$ values for bitewing, Pax-500ECT, and Promax 3D imaging systems were 0.882, 0.995, and 0.978, respectively. Significant differences were found between the two CBCT systems and film (p=0.007). For CBCT systems, the axial plane showed the greatest $A_z$ value. Conclusion : Based on the design of this study, CBCT images were better than bitewing radiographs in detection of secondary caries.

• Imaging Science in Dentistry
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• 제45권1호
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• pp.31-39
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• 2015

Purpose: This study was performed to evaluate the feasibility of visualizing soft tissue lesions and vascular structures using contrast-enhanced cone-beam computed tomography (CE-CBCT) after the intravenous administration of a contrast medium in an animal model. Materials and Methods: CBCT was performed on six rabbits after a contrast medium was administered using an injection dose of 2 mL/kg body weight and an injection rate of 1 mL/s via the ear vein or femoral vein under general anesthesia. Artificial soft tissue lesions were created through the transplantation of autologous fatty tissue into the salivary gland. Volume rendering reconstruction, maximum intensity projection, and multiplanar reconstruction images were reconstructed and evaluated in order to visualize soft tissue contrast and vascular structures. Results: The contrast enhancement of soft tissue was possible using all contrast medium injection parameters. An adequate contrast medium injection parameter for facilitating effective CE-CBCT was a 5-mL injection before exposure combined with a continuous 5-mL injection during scanning. Artificial soft tissue lesions were successfully created in the animals. The CE-CBCT images demonstrated adequate opacification of the soft tissues and vascular structures. Conclusion: Despite limited soft tissue resolution, the opacification of vascular structures was observed and artificial soft tissue lesions were visualized with sufficient contrast to the surrounding structures. The vascular structures and soft tissue lesions appeared well delineated in the CE-CBCT images, which was probably due to the superior spatial resolution of CE-CBCT compared to other techniques, such as multislice computed tomography.

• 대한방사선치료학회지
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• 제35권
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• pp.41-51
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• 2023

목 적: 본 연구는 폐암 환자의 정위체부방사선치료 시(Stereotactic Body Radiation Therapy, SBRT) 기준선(Baseline) 변화에 따른 3D-CBCT(Cone Beam Computed-Tomography)와 Gated-CBCT의 영상 품질(Image quality)을 비교 분석하여 호흡에 따른 움직임의 보정에 유용한 CBCT 촬영 방법을 찾고자 한다. 대상 및 방법: QUASAR^TM(Modus Medical Devices Inc, Canada) 팬텀에 지름이 3 cm인 고체 종양 물질(Solid Tumor)을 삽입하여 팬텀의 속도를 주기 3 sec, 최대 진폭 20 mm 로 4DCT(4-Dimentional Computed-Tomography)를 촬영하였다. 전산화 치료계획시스템 Eclipse^TM을 이용하여 고체 종양 물질에 육안적 종양용적(Gross Target Volume, GTV)을 윤곽 묘사하였다. Truebeam STx^TM을 이용해 4DCT 촬영 시와 동일하게 설정한 후, 기준선 변화가 1 mm, 3 mm, 5 mm인 호흡 패턴을 팬텀에 입력하여 3D-CBCT(Spotlight, Full)와 Gated-CBCT(Spotlight, Full) 영상을 5회 반복하여 획득하였다. 획득된 영상을 4DCT 영상을 기준으로 신호대잡음비(Signal-to-Noise Ratio, SNR), 대조대잡음비(Contrast-to-Noise Ratio, CNR), 종양 체적 길이(Tumor Volume Length) 및 모션 블러링 비(Motion Blurring Ratio, MBR)를 측정하여 비교하였다. 결 과: Spotlight Gated-CBCT 영상이 기준선 변화에 따른 신호대잡음비가 평균 13.30±0.10%, 대조대잡음비가 평균 7.78±0.16%, 종양 체적 길이가 평균 3.55 ± 0.17%, 모션 블러링 비가 평균 1.18 ± 0.06%로 Spotlight 3D-CBCT보다 우수한 값을 보였다. 또한, Full Gated-CBCT 영상이 기준선 변화에 따른 신호대잡음비가 평균 12.80 ± 0.11%, 대조대잡음비가 평균 7.60 ± 0.11%, 종양 체적 길이가 평균 3.54 ± 0.16%, 모션 블러링 비가 평균 1.18 ± 0.05%로 Full 3D-CBCT보다 우수한 값을 보였다. 결 론: 3D-CBCT 촬영 영상과 비교하여 Gated-CBCT 촬영 영상이 기준선 변화에 따른 영상 품질이 우수한 값을 보였으며, 호흡으로 인한 모션 블러링 인공물(Motion Blurring Artifacts)의 영향이 적은 것을 확인했다. 따라서 단기간에 고선량을 전달하는 폐암의 정위체부방사선치료 시 불규칙한 호흡으로 인한 기준선 변화가 발생하는 경우 Gated-CBCT를 이용해 영상유도(Image Guide)를 하는 것이 유용하다고 판단된다.

• Imaging Science in Dentistry
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• 제51권2호
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• pp.93-106
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• 2021

Purpose: This study was conducted to review the literature regarding the types of cone-beam computed tomography (CBCT) artifacts around dental implants and the factors that influence their formation. Materials and Methods: A search strategy was carried out in the PubMed, Embase, and Scopus databases to identify published between 2010 and 2020, and 9 studies were selected. The implants included 306 titanium, titanium-zirconium, and zirconia implants, as well as 5 titanium cylinders. Results: The artifacts around the implants were the beam-hardening artifact, the streaking artifact, and band-like radiolucent areas. Some factors that influenced the formation of artifacts were the implant material, bone type, evaluated regions, distance, type of CBCT, field of view (FOV) size, milliamperage, peak kilovoltage (kVp), and voxel size. The beam-hardening artifact was the most widely reported, and it was minimized in protocols with a smaller FOV, larger voxels, and higher kVp. Conclusion: The risk and benefit of these protocols in individuals with dental implants must be considered, and clinical examinations and complementary radiographs play an essential role in implantology.

• Imaging Science in Dentistry
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• 제53권1호
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• pp.69-75
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• 2023

Purpose: Maxillofacial trauma predominantly affects young adults between 20 and 40 years of age. Although radioprotection is a legal requirement, the significant potential of dose reduction in computed tomography (CT) is still underused in the clinical routine. The objective of this study was to evaluate whether maxillofacial fractures can be reliably detected and classified using ultra-low-dose CT. Materials and Methods: CT images of 123 clinical cases with maxillofacial fractures were classified by two readers using the AOCOIAC software and compared with the corresponding results from post-treatment images. In group 1, consisting of 97 patients with isolated facial trauma, pre-treatment CT images at different dose levels (volumetric computed tomography dose index: ultra-low dose, 2.6 mGy; low dose, <10 mGy; and regular dose, <20 mGy) were compared with post-treatment cone-beam computed tomography (CBCT). In group 2, consisting of 31 patients with complex midface fractures, pre-treatment shock room CT images were compared with post-treatment CT at different dose levels or CBCT. All images were presented in random order and classified by 2 readers blinded to the clinical results. All cases with an unequal classification were re-evaluated. Results: In both groups, ultra-low-dose CT had no clinically relevant effect on fracture classification. Fourteen cases in group 2 showed minor differences in the classification code, which were no longer obvious after comparing the images directly to each other. Conclusion: Ultra-low-dose CT images allowed the correct diagnosis and classification of maxillofacial fractures. These results might lead to a substantial reconsideration of current reference dose levels.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제31권2호
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• pp.158-166
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• 2009

The application of CT with basis on 3 dimensional-reconstruction is getting more widely practiced. With the data obtained from cone-beam computed tomography(CBCT), not only the diagnosis of the patient with skeletal abnormality but also the virtual simulation of the orthognathic surgery were performed and its application would be popular in orthodontic field. We reported a case, a 19-year old man who was diagnosed mandibular prognathism and required orthognatic surgery. In this case, the virtual orthognathic surgery was simulated and surgical wafer was fabricated by using CBCT data. That wafer was applied the actual orthognathic surgery. After preoperative orthodontic treatment, we prepared surgery as follows. : (l)Acquisition of 3D image data, (2)Reconstruction of 3-dimensional virtual model, (3)Virtual model surgery, (4)Extraction of stere-olithographic image, (5)Check-up for occlusal interference, (6)Fabrication of surgical stent by stereolithography. Bilateral sagittal split ramus osteotomy was operated and used stereolithographic surgical stent. 1 month later, we superimposed CBCT datas of virtual surgery and that of actual surgery, and then compared the result. CT data's application for othognathic surgery yielded satisfactory outcomes.