Accuracy and reliability of stitched cone-beam computed tomography images

Egbert, Nicholas,Cagna, David R.,Ahuja, Swati,Wicks, Russell A. Korean Academy of Oral and Maxillofacial Radiology 2015 Imaging Science in Dentistry Vol.45 No.1

Purpose: This study was performed to evaluate the linear distance accuracy and reliability of stitched small field of view (FOV) cone-beam computed tomography (CBCT) reconstructed images for the fabrication of implant surgical guides. Material and Methods: Three gutta percha points were fixed on the inferior border of a cadaveric mandible to serve as control reference points. Ten additional gutta percha points, representing fiduciary markers, were scattered on the buccal and lingual cortices at the level of the proposed complete denture flange. A digital caliper was used to measure the distance between the reference points and fiduciary markers, which represented the anatomic linear dimension. The mandible was scanned using small FOV CBCT, and the images were then reconstructed and stitched using the manufacturer's imaging software. The same measurements were then taken with the CBCT software. Results: The anatomic linear dimension measurements and stitched small FOV CBCT measurements were statistically evaluated for linear accuracy. The mean difference between the anatomic linear dimension measurements and the stitched small FOV CBCT measurements was found to be 0.34 mm with a 95% confidence interval of +0.24 - +0.44 mm and a mean standard deviation of 0.30 mm. The difference between the control and the stitched small FOV CBCT measurements was insignificant within the parameters defined by this study. Conclusion: The proven accuracy of stitched small FOV CBCT data sets may allow image-guided fabrication of implant surgical stents from such data sets.

Accuracy and reliability of stitched cone-beam computed tomography images

Nicholas Egbert,David R. Cagna,Swati Ahuja,Russell A. Wicks 대한영상치의학회 2015 Imaging Science in Dentistry Vol.45 No.1

Purpose: This study was performed to evaluate the linear distance accuracy and reliability of stitched small field of view (FOV) cone-beam computed tomography (CBCT) reconstructed images for the fabrication of implant surgical guides. Material and Methods: Three gutta percha points were fixed on the inferior border of a cadaveric mandible to serve as control reference points. Ten additional gutta percha points, representing fiduciary markers, were scattered on the buccal and lingual cortices at the level of the proposed complete denture flange. A digital caliper was used to measure the distance between the reference points and fiduciary markers, which represented the anatomic linear dimension. The mandible was scanned using small FOV CBCT, and the images were then reconstructed and stitched using the manufacturer’s imaging software. The same measurements were then taken with the CBCT software. Results: The anatomic linear dimension measurements and stitched small FOV CBCT measurements were statistically evaluated for linear accuracy. The mean difference between the anatomic linear dimension measurements and the stitched small FOV CBCT measurements was found to be 0.34 mm with a 95% confidence interval of +0.24 - +0.44 mm and a mean standard deviation of 0.30 mm. The difference between the control and the stitched small FOV CBCT measurements was insignificant within the parameters defined by this study. Conclusion: The proven accuracy of stitched small FOV CBCT data sets may allow image-guided fabrication of implant surgical stents from such data sets.

계절별 위성자료를 이용한 미국 캔자스주 식생 분류 -하이브리드 접근방식의 적용-

박선엽(Sunyurp Park),Stephen Egbert(Stephen Egbert),Dana Peterson(Dana Peterson),Aimee Stewart(Aimee Stewart),Chris Lauver(Chris Lauver),Kevin Price(Kevin Price),Clayton Blodgett(Clayton Blodgett),Jack C 대한지리학회 2003 대한지리학회지 Vol.38 No.5

미국 캔자스주 정부와 연방정부가 필요로 하는 상세한 지표피복 수치지도제작을 위해, Landsat Thematic Mapper 자료를 이용하여 캔자스주 전체를 대상으로 43가지로 분류된 식생군단(vegetation alliance) 수준의 자연식생지도를 제작하였다. 지도제작 방법으로는 봄, 여름, 가을의 계절별 위성자료를 이용하여 두 단계 분류절차를 거치는 이른바 '하이브리드(hybrid)' 방식을 채택하였다. 이 접근 방법은 첫 단계로 unsupervised classification을 이용, 자연녹지를 농경지로부터 분리해 낸 다음, 두 번째 단계에서 supervised classification, 현장확인조사, 그리고 분류 후 다양한 보강자료를 이용하여 최종적으로 자연식생을 구분·분류해 내는 것이다. 정확도 평가는 세 가지 분류 수준에서 실행되었는데, 이는 앤더슨 분류단계 I(Anderson level I). 식생군계(vegetation formation). 그리고 식생군단 수준을 포함한다. 확인결과 전반적인 정확도는 51.7%에서 89.4%에 이르는 것으로 조사되었다. To address the requirements of gap analysis for species protection, as well as the needs of state and federal agencies for detailed digital land cover, a 43-class map at the vegetation alliance level was created for the state of Kansas using multi-temporal Thematic Mapper imagery. The mapping approach included the use of three-date multi-seasonal imagery, a two-stage classification approach that first masked out cropland areas using unsupervised classification and then mapped natural vegetation with supervised classification, visualization techniques utilizing a map of small multiples and field experts, and extensive use of ancillary data in post-hoc processing. Accuracy assessment was conducted at three levels of generalization (Anderson Level I, vegetation formation, and vegetation alliance) and three cross-tabulation approaches. Overall accuracy ranged from 51. 7% to 89.4%, depending on level of generalization, while accuracy figures for individual alliance classes varied by area covered and level of sampling.<br/> Key Words: natural vegetation, hybrid, Anderson level I, formation, alliance.

Using Multi-Dimensional Analysis to Study Register Variation on the Searchable Web

Douglas Biber,Jesse Egbert 한국코퍼스언어학회 2016 Corpus Linguistics Research Vol.2 No.-

Most previous linguistic studies of web language have focused on the ‘new’ internet registers, like blogs, instant messages, and tweets. As a result, we know surprisingly little about the patterns of linguistic variation among the full range of registers found on the searchable web. The present paper provides an overview of a project that begins to fill this gap. Rather than collecting texts from only the ‘new’ web registers, the project is based on a large corpus representing a random sample of the entire searchable web. The first analytical step in the project was to analyze the types of documents found in that corpus, providing an empirical description of the composition of the searchable web. Then, Multi-Dimensional (MD) analysis was applied to describe the patterns of register variation found on the searchable web. The MD analysis first identified the sets of co-occurring linguistic features -- the ‘dimensions’ -- in this discourse domain. Then, those dimensions are used to document the similarities and differences among web registers. In conclusion, we compare our results here to previous MD studies, identifying patterns peculiar to the web versus linguistic patterns found across discourse domains.

미중부지역 농지보전 프로그램에 의한 경관구조 변화분석

박선엽(Park Seon Yeob),Stephen L. Egbert 한국지역지리학회 2003 한국지역지리학회지 Vol.9 No.4

미전역에 걸쳐 80년대 중반부터 시행된 미농지보전 프로그램(CRP)은 1992년까지 약 1480만 헥타르에 이르는 농경지를 초지, 임지, 삼림, 또는 기타 보전용도로 전환하였다. CRP 시행에 의한 한 가지 주요결과는 수백만 헥타르에 이르는 초지를 확보함으로써 야생동물을 위한 잠재서식처 면적을 현저하게 증가시킨 점이다. 본 연구는 CRP 시행에 따른 자연경관의 공간구조변화를 지역적으로 살펴보고자 하였다. 이를 위해, 계절별 Landsat Thematic Mapper 자료를 이용하여 캔자스주 남서부 6개 카운티에 대한 CRP 시행 이전과 이후의 경지 및 초지분포 지도를 생성하였다. 다음으로, 분류후 차이분석기법(post-classification differencing)을 적용하여 경지에서 초지로 전환된 지역의 분포를 파악해내었다. 공간구조분석 프로그램 FRAGSTATS을 이용하여 지표피복의 공간패턴을 나타내는 10개 주요 통계지표를 계산함으로써 CRP 시행에 따르는 경관구조변화를 살펴보았다. 연구지역에 미친 CRP의 주요 영향은, 전반적으로 자연초지 분포의 분절화가 현격하게 감소했다는 것이다. 야생동물 서식처관리의 측면에서 CRP 초지의 도입은 지편(地片)의 수, 평균 지편 크기, 지편 내부면적 등을 크게 증가시키는 효과를 낳았다. 또한, CRP 시행은 녹지간 연결성 및 결합도를 높였는데, 이는 넓게 연속된 서식처를 요하는 종들을 보호하는 데에 잠재적인 가치를 지닐 것으로 보인다. 끝으로, CRP는 이웃한 녹지간 거리를 감소시킴으로써 생물종들의 녹지간 이동을 용이하게 할 것이다. CRP 시행은 캔자스주 남서부 지역의 자연공간구조를 현저히 변화시킨 주요요인으로 나타났으며, 이는 향해 야생동물 서식처 보호를 위한 중요한 의미를 갖는다. The U.S. Conservation Reserve Progrant (CRP) resulted in the conversion of approximately 14.8 million ha(36.5 million acres) of cropland to grassland, woodland, and other conservation uses throughout the U.S. between 1986 and 1992. One of the major results of CRP has been the addition of millions of hectares of potential wildlife habitat, primarily as grassland .In this study, we examined regional changes in landscape structure caused by the introduction of CRP. Utilizing multi-seasonal Landsat Thematic Mapper imagery, we produced maps of cropland and grassland for the pre and post-CRP enrollment periods for a six- county region in southwest Kansas. We then applied post-classification differencing to identify regions of cropland that had been converted to CRP. Using the FRAGSTATS spatial pattern analysis program, we calculated a variety of spatial statistics to analyze changes in landscape structure due to CRP. The major impact of CRP in the six country study area has been the reversal of an overall trend of grassland habitat fragmentation. From the standpoint of potential wildlife habitat, the introduction of CRP has greatly increased the number of patches, mean patch size, and the interior or core are of grassland patches. In addition, CRP has increased connectivity and aggregation between grassland patches, potentially important factors for species of conservation interest, particularly those that require larger expanses of unbroken habitat. Finally, the distance between neighboring patches of grassland has decreased, reducing travel distance between patches, Clearly, the introduction of CRP substantially modified the spatial structure of the southwest Kansas landscape, with important implications for wildlife habitat.

Exploitation of the Dose/Time-Response Relationship for a New Measure of DNA Repair in the Single-Cell Gel Electrophoresis (Comet) Assay

Byung-Soo Kim,Lutz Edler,Jin Joo Park,Dietrich von Fournier,Wulf Haase,Marie-Luise Sautter-Bihl,Egbert Hagmuller,Florian Gotzes,Heinz Walter Thielmann 한국독성학회 2004 Toxicological Research Vol.20 No.1

The comet assay (also called the single-cell gel electrophoresis assay) has been widely used for detecting DNA damage and repair in individual cells. Since the conventional methods of evaluating comet assay data using frequency statistics are unsatisfactory we developed a new quantitative measure of DNA damage/repair that is based on all information residing in the dose/time-response curves of a comet experiment. Blood samples were taken from 25 breast cancer patients before undergoing radiotherapy. The comet assay was performed under alkaline conditions using isolated lymphocytes. Tail DNA, tail length, tail moment and tail inertia of the comet were measured for each patient at four doses of g-rays (0, 2, 4 and 8 Gy) and at four time points after irradiation (0, 10, 20 and 30 min) using 100 cells each. The resulting three-dimensional dose-time response surface was modeled by multiple regression, and the second derivative, termed 2D, on dose and time was determined. A software module was programmed in SAS/AF to compute 2D values. We applied the new method successfully to data obtained from cancer patients to be assessed for their radiation sensitivity. We computed the 2D values for the four damage measures, i.e., tail<br/> moment, tail length, tail DNA and tail inertia, and examined the pairwise correlation coefficients of 2D both on the log scale and the unlogged scale. 2D values based on tail moment and tail DNA<br/> showed a high correlation and, therefore, these two damage measures can be used interchangeably as far as DNA repair is concerned. 2D values based on tail inertia have a correlation profile different from the other 2D values which may reflect different facets of DNA damage/repair. Using the dose-time response surface, other statistical models, e.g., the proportional hazards model, become applicable for data analysis. The 2D approach can be applied to all DNA repair measures, i.e., tail moment, tail length, tail DNA and tail inertia, and appears to be superior to conventional evaluation methods as it integrates all data of the dose/time-response curves of a comet assay.

Exploitation of the Dose/Time-Response Relationship for a New Measure of DNA Repari in the Single-Cell Gel Electrophoresis (Comet) Assay

Kim, Byung-Soo,Edler, Lutz,Park, Jin-Joo,Fournier, Dietrich Von,Haase, Wulf,Sautter-Bihl, Mare-Luise,Hagmuller, Egbert,Gotzes, Florian,Thielmann, Heinz Walter Korean Society of ToxicologyKorea Environmental Mu 2004 Toxicological Research Vol.20 No.2

The comet assay (also called the single-cell gel electrophoresis assay) has been widely used for detecting DNA damage and repair in individual cells. Since the conventional methods of evaluating comet assay data using frequency statistics are unsatisfactory we developed a new quantitative measure of DNA damage/repair that is based on all information residing in the dose/time-response curves of a comet experiment. Blood samples were taken from 25 breast cancer patients before undergoing radiotherapy. The comet assay was performed under alkaline conditions using isolated lymphocytes. Tail DNA, tail length, tail moment and tail inertia of the comet were measured for each patient at four doses of $\gamma$-rays (0, 2, 4 and 8 Gy) and at four time points after irradiation (0, 10, 20 and 30 min) using 100 cells each. The resulting three-dimensional dose-time response surface was modeled by multiple regression, and the second derivative, termed 2D, on dose and time was determined. A software module was programmed in SAS/AF to compute 2D values. We applied the new method successfully to data obtained from cancer patients to be assessed for their radiation sensitivity. We computed the 2D values for the four damage measures, i.e., tail moment, tail length, tail DNA and tail inertia, and examined the pairwise correlation coefficients of 2D both on the log scale and the unlogged scale. 2D values based on tail moment and tail DNA showed a high correlation and, therefore, these two damage measures can be used interchangeably as far as DNA repair is concerned. 2D values based on tail inertia have a correlation profile different from the other 2D values which may reflect different facets of DNA damage/repair. Using the dose-time response surface, other statistical models, e.g., the proportional hazards model, become applicable for data analysis. The 2D approach can be applied to all DNA repair measures, Le., tail moment, tail length, tail DNA and tail inertia, and appears to be superior to conventional evaluation methods as it integrates all data of the dose/time-response curves of a comet assay.

Exploitation of the Dose/Time-Response Relationship for a New Measure of DNA Repair in the Single-Cell Gel Electrophoresis (Comet) Assayof DNA Repair in the Single-Cell Gel Electrophoresis (Comet) Assay

Byung-Soo Kim,Lutz Edler,Jin Joo Park,Dietrich von Fournier,Wulf Haase,Marie-Luise Sautter-Bihl,Egbert Hagmuller,Florian Gotzes,Heinz Walter Thielmann 한국독성학회 2004 Toxicological Research Vol.20 No.2

The comet assay (also called the single-cell gel electrophoresis assay) has been widely used for detecting DNA damage and repair in individual cells. Since the conventional methods of evaluating comet assay data using frequency statistics are unsatisfactory we developed a new quantitative measure of DNA damage/repair that is based on all information residing in the dose/time-response curves of a comet experiment. Blood samples were taken from 25 breast cancer patients before undergoing radiotherapy. The comet assay was performed under alkaline conditions using isolated lymphocytes. Tail DNA, tail length, tail moment and tail inertia of the comet were measured for each patient at four doses of g-rays (0, 2, 4 and 8 Gy) and at four time points after irradiation (0, 10, 20 and 30 min) using 100 cells each. The resulting three-dimensional dose-time response surface was modeled by multiple regression, and the second derivative, termed 2D, on dose and time was determined. A software module was programmed in SAS/AF to compute 2D values.<br/> We applied the new method successfully to data obtained from cancer patients to be assessed for their radiation sensitivity. We computed the 2D values for the four damage measures, i.e., tail<br/> moment, tail length, tail DNA and tail inertia, and examined the pairwise correlation coefficients of 2D both on the log scale and the unlogged scale. 2D values based on tail moment and tail DNA<br/> showed a high correlation and, therefore, these two damage measures can be used interchangeably as far as DNA repair is concerned. 2D values based on tail inertia have a correlation profile different from the other 2D values which may reflect different facets of DNA damage/repair. Using the dose-time response surface, other statistical models, e.g., the proportional hazards model, become applicable for data analysis. The 2D approach can be applied to all DNA repair measures, i.e., tail moment, tail length, tail DNA and tail inertia, and appears to be superior to conventional evaluation methods as it integrates all data of the dose/time-response curves of a comet assay.

Differentiation of Korean isolates of Entamoeba histolytica from Entamoeba dispar

Seong-Choon CHOE(최성준),Mejeong Lee(이미정),Sang-Kum LEE(이상금),Kyung-il IM(임경일),Egbert TANNICH,Soon-Hyung LEE(이순형),Sung-Tae HONG(홍성태) 대한기생충학열대의학회 1996 The Korean Journal of Parasitology Vol.34 No.1