Mountainous regions have disadvantages in economic development because of harsh physical and climatic conditions.However,winter tourism activities are one of the key components for supporting economic development in t...Mountainous regions have disadvantages in economic development because of harsh physical and climatic conditions.However,winter tourism activities are one of the key components for supporting economic development in the highlands.Establishing a ski resort area supports direct and indirect employment in a region,and it stops immigration from mountainous regions to other places.This research aimed to assess the potential ski areas using a multi criteria evaluation technique in the Van region which is located in the eastern part of Türkiye.In this context,snow cover duration,sun effect,slope,slope length,elevation,population density,distance from main roads and lake visibility were used as input factors in the decision making process.Each factor was standardized using a fuzzy technique based on existing well-known ski centers in Türkiye.The weight of inputs was defined by applying a survey to the professional skiers.The most important factors were detected as transportation opportunities and snow covers whereas,the least important factors were elevation and population density.Additionally,lake visibility was very important to make a difference from other existing facilities in the region.Therefore,it was included as constraints and lake visible areas were extracted at the final stage of the research.Potential ski areas were mapped in three levels as professional,intermediate and beginner skiers.One of the suitable areas was selected as a sample projection and for the 3D simulation of the ski investment area.Potential costs and benefits were discussed.It was found that a ski tourism area investment can be amortized in 3 years in the region.展开更多
Objective: It is important and helpful for surgeons to understand the correlation between spinal anatomy and screw trajectory before surgery. We aimed to assess a simple technique using 3D imaging software available o...Objective: It is important and helpful for surgeons to understand the correlation between spinal anatomy and screw trajectory before surgery. We aimed to assess a simple technique using 3D imaging software available on the hospital intranet for visual and quantitative feedback to prepare surgeons for an appropriate entry point and safe trajectory when placing cervical screws. Methods: A total of 59 cervical screws were inserted from C1 to T1 in 12 consecutive patients using this technique. First, a single CT optimal slice was selected from 3D CT images of the cervical spine to determine the intervals of bilateral entry points and lateral angle. Next, this 3D image was rotated to the lateral angle. Finally, bone was cut out on the entry point using subtractive manipulation, which removed the core of the pedicle or lateral mass. Screw trajectory was indicated, and surgeons could assess the correlation between surface landmarks, spinal anatomy, and screw trajectory. Posterior cervical fusion was performed using fluoroscopy. Postoperative outcomes and incidence of complications were retrospectively assessed. Results: One perforation (1.4%) was identified on postoperative CT images. No vascular injuries occurred. Differences in the intended entry point location and lateral angle of the screw from actual postoperative values were 1.49 ± 1.23 mm and 5.46。 ± 4.46。, respectively. Conclusions: A novel 3D CT imaging assessment underwent in cervical screw fixation. This technique is easily accessible on the hospital intranet and provides training in cervical screw placement for fellows. Surgeons can simulate screw placement and share surgical strategy.展开更多
In order to verify the validity of finite element numerical simulation method for asphalt mixture, which consists of aggregates, mastic （where mastic is a kind of fine mixture composed of asphalt binder mixed with fi...In order to verify the validity of finite element numerical simulation method for asphalt mixture, which consists of aggregates, mastic （where mastic is a kind of fine mixture composed of asphalt binder mixed with fines and fine aggregates） and air voids, based on three-dimensional （3D） heterogeneous specimen, X-ray computerized tomography （X-ray CT） was used to scan the asphalt specimens to obtain the real internal microstrnctures of asphalt mixture. CT images were reconstructed to build up 3D digital specimen, and the viscoelastic properties of mastic were described with Burgers model The uniaxial creep numerical simulations of three different levels of aggregate gradation were conducted. The simulation results agree well with the experimental results. The numerical simulation of asphalt mixture incorporated with real 3D microstructure based on finite element method is a promising application to conduct research of asphalt concrete. Additionally, this method can increase the mechanistic understanding of global viscoelastic properties of asphalt mixtures by linking the real 3D microstructure.展开更多
Three-dimensional(3D)reconstruction of the equivalent pore network model(PNM)using X-ray computed tomography(CT)data are of significance for studying the CO_(2)-enhanced coalbed methane recovery(CO_(2)-ECBM).The docki...Three-dimensional(3D)reconstruction of the equivalent pore network model(PNM)using X-ray computed tomography(CT)data are of significance for studying the CO_(2)-enhanced coalbed methane recovery(CO_(2)-ECBM).The docking among X-ray CT technology,MATLAB,with COMSOL software not only can realize the 3D reconstruction of PNM,but also the CO_(2)-ECBM process simulation.The results show that the Median filtering algorithm enabled the de-noising of the original 2D CT slices,the image segmentation of all slices was realized based on the selected threshold,and the PNM can be constructed based on the Maximum Sphere algorithm.The mathematical model of CO_(2)-ECBM process fully coupled the expanded Langmuir equation.At the same time for CO_(2)injection,CH_(4)pressure tends to decrease with the increase of CO_(2)pressure,but its difference is not obvious.The CH_(4)pressure in the slice center changed a lot,while at the edge it changed a little under different CO_(2)pressures.The injected CO_(2)was transported to matrix along the macro and micro-fractures with continuous flow.The injected CO_(2)first replaced the adsorbed CH_(4)by covering the inner surface of macro-pores and meso-pores to form the single molecular layer adsorption of CO_(2).Then they migrated to micro-pores by Fick’s diffusion,sliding flow,and surface diffusion.Furthermore,the CO_(2)replaced CH_(4)adsorbed by volumetric filling in micro-pores,and formed the multi-molecular layer adsorption of CO_(2).The gas pressure and migration path between CO_(2)and CH_(4)are opposite.This study can provide a theoretical basis for studying digital rock physics technology and enrich the development of CO_(2)-ECBM technology.展开更多
X-ray imaging is the conventional method for diagnosing the orthopedic condition of a patient. Computerized Tomography(CT) scanning is another diagnostic method that provides patient’s 3D anatomical information. Howe...X-ray imaging is the conventional method for diagnosing the orthopedic condition of a patient. Computerized Tomography(CT) scanning is another diagnostic method that provides patient’s 3D anatomical information. However, both methods have limitations when diagnosing the whole leg; X-ray imaging does not provide 3D information, and normal CT scanning cannot be performed with a standing posture. Obtaining 3D data regarding the whole leg in a standing posture is clinically important because it enables 3D analysis in the weight bearing condition.Based on these clinical needs, a hardware-based bi-plane X-ray imaging system has been developed; it uses two orthogonal X-ray images. However, such methods have not been made available in general clinics because of the hight cost. Therefore, we proposed a widely adaptive method for 2 D X-ray image and 3D CT scan data. By this method, it is possible to threedimensionally analyze the whole leg in standing posture. The optimal position that generates the most similar image is the captured X-ray image. The algorithm verifies the similarity using the performance of the proposed method by simulation-based experiments. Then, we analyzed the internal-external rotation angle of the femur using real patient data. Approximately 10.55 degrees of internal rotations were found relative to the defined anterior-posterior direction. In this paper, we present a useful registration method using the conventional X-ray image and 3D CT scan data to analyze the whole leg in the weight-bearing condition.展开更多
For local radiotherapy, a three-dimensional(3D)conformal localized dose planning protocol has been established in this paper to develop a precise and reasonable dose plan. A precalculated 3D dose map for a single sour...For local radiotherapy, a three-dimensional(3D)conformal localized dose planning protocol has been established in this paper to develop a precise and reasonable dose plan. A precalculated 3D dose map for a single source is obtained using the Monte Carlo method, and the spatial dose maps are combined linearly to acquire the dose distribution. The dose distribution is visualized through the real-time display of the isodose line and isodose surface combined with the reconstructed 3D organ groups. By observing 3D dose coverage to the target volume and surrounding tissues, dose planning could be initiated with greater accuracy and precision to avoid dose dead zones and excessively high-dose levels, thus achieving the 3D conformal dose planning objective. Further research into the impact that blockages have on a needle trajectory can be conducted to optimize the insertion accuracy. A treatment planning system was developed to formulate and implement the 3D local treatment plan before the surgery,during the surgery, and after the surgery. Several experiments pertaining to both single-seed and multiple-seed dose distributions were conducted to verify the accuracy of the single-seed dose calculation module and 3D superposition dose calculation in the treatment planning system.展开更多
Modern radiation treatments have become fairly complex and involve in utilizing a variety of medical devices to achieve the goal of providing conformal radiation dose coverage to the tumor target(s)while maximizing th...Modern radiation treatments have become fairly complex and involve in utilizing a variety of medical devices to achieve the goal of providing conformal radiation dose coverage to the tumor target(s)while maximizing the sparing of normal organ structures.Recently,different forms of linear accelerators/radioactive source based machines have been invented and developed with the aim of providing improved treatments and more treatment options.Besides linear accelerators(Linac)that have been undergoing constant improvement and advancement and can deliver fairly complicated dose distribution patterns,imaging systems,computer information and calculation systems have been more and more integrated into radiotherapy processes.To bring radiotherapy to a potentially higher level,many institutions have either acquired or started to consider particle therapy,especially proton therapy.The complexity of modern radiotherapy demands in-depth understanding of radiation physics and machine engineering as well as computer information systems.This paper is intended to provide an introductory description of radiation oncology and related procedures,and to provide an overview of the current status of medical devices in radiotherapy in the United States of America.This paper covers the radiation delivery systems,imaging systems,treatment planning systems,record and verify systems,and QA systems.展开更多
文摘Mountainous regions have disadvantages in economic development because of harsh physical and climatic conditions.However,winter tourism activities are one of the key components for supporting economic development in the highlands.Establishing a ski resort area supports direct and indirect employment in a region,and it stops immigration from mountainous regions to other places.This research aimed to assess the potential ski areas using a multi criteria evaluation technique in the Van region which is located in the eastern part of Türkiye.In this context,snow cover duration,sun effect,slope,slope length,elevation,population density,distance from main roads and lake visibility were used as input factors in the decision making process.Each factor was standardized using a fuzzy technique based on existing well-known ski centers in Türkiye.The weight of inputs was defined by applying a survey to the professional skiers.The most important factors were detected as transportation opportunities and snow covers whereas,the least important factors were elevation and population density.Additionally,lake visibility was very important to make a difference from other existing facilities in the region.Therefore,it was included as constraints and lake visible areas were extracted at the final stage of the research.Potential ski areas were mapped in three levels as professional,intermediate and beginner skiers.One of the suitable areas was selected as a sample projection and for the 3D simulation of the ski investment area.Potential costs and benefits were discussed.It was found that a ski tourism area investment can be amortized in 3 years in the region.
文摘Objective: It is important and helpful for surgeons to understand the correlation between spinal anatomy and screw trajectory before surgery. We aimed to assess a simple technique using 3D imaging software available on the hospital intranet for visual and quantitative feedback to prepare surgeons for an appropriate entry point and safe trajectory when placing cervical screws. Methods: A total of 59 cervical screws were inserted from C1 to T1 in 12 consecutive patients using this technique. First, a single CT optimal slice was selected from 3D CT images of the cervical spine to determine the intervals of bilateral entry points and lateral angle. Next, this 3D image was rotated to the lateral angle. Finally, bone was cut out on the entry point using subtractive manipulation, which removed the core of the pedicle or lateral mass. Screw trajectory was indicated, and surgeons could assess the correlation between surface landmarks, spinal anatomy, and screw trajectory. Posterior cervical fusion was performed using fluoroscopy. Postoperative outcomes and incidence of complications were retrospectively assessed. Results: One perforation (1.4%) was identified on postoperative CT images. No vascular injuries occurred. Differences in the intended entry point location and lateral angle of the screw from actual postoperative values were 1.49 ± 1.23 mm and 5.46。 ± 4.46。, respectively. Conclusions: A novel 3D CT imaging assessment underwent in cervical screw fixation. This technique is easily accessible on the hospital intranet and provides training in cervical screw placement for fellows. Surgeons can simulate screw placement and share surgical strategy.
基金Project(51038004) supported by the National Natural Science Foundation of China
文摘In order to verify the validity of finite element numerical simulation method for asphalt mixture, which consists of aggregates, mastic （where mastic is a kind of fine mixture composed of asphalt binder mixed with fines and fine aggregates） and air voids, based on three-dimensional （3D） heterogeneous specimen, X-ray computerized tomography （X-ray CT） was used to scan the asphalt specimens to obtain the real internal microstrnctures of asphalt mixture. CT images were reconstructed to build up 3D digital specimen, and the viscoelastic properties of mastic were described with Burgers model The uniaxial creep numerical simulations of three different levels of aggregate gradation were conducted. The simulation results agree well with the experimental results. The numerical simulation of asphalt mixture incorporated with real 3D microstructure based on finite element method is a promising application to conduct research of asphalt concrete. Additionally, this method can increase the mechanistic understanding of global viscoelastic properties of asphalt mixtures by linking the real 3D microstructure.
基金This work was financially supported by the University Synergy Innovation Program of Anhui Province(No.GXXT-2021-018)the Natural Science Research Project of Anhui University(Nos.KJ2020A0315,KJ2020A0317)+2 种基金the Natural Science Foundation of Anhui Province(No.2108085MD134)the National Natural Science Foundation of China(No.41902168)the Foundation of State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing(No.PRP/open-2005).
文摘Three-dimensional(3D)reconstruction of the equivalent pore network model(PNM)using X-ray computed tomography(CT)data are of significance for studying the CO_(2)-enhanced coalbed methane recovery(CO_(2)-ECBM).The docking among X-ray CT technology,MATLAB,with COMSOL software not only can realize the 3D reconstruction of PNM,but also the CO_(2)-ECBM process simulation.The results show that the Median filtering algorithm enabled the de-noising of the original 2D CT slices,the image segmentation of all slices was realized based on the selected threshold,and the PNM can be constructed based on the Maximum Sphere algorithm.The mathematical model of CO_(2)-ECBM process fully coupled the expanded Langmuir equation.At the same time for CO_(2)injection,CH_(4)pressure tends to decrease with the increase of CO_(2)pressure,but its difference is not obvious.The CH_(4)pressure in the slice center changed a lot,while at the edge it changed a little under different CO_(2)pressures.The injected CO_(2)was transported to matrix along the macro and micro-fractures with continuous flow.The injected CO_(2)first replaced the adsorbed CH_(4)by covering the inner surface of macro-pores and meso-pores to form the single molecular layer adsorption of CO_(2).Then they migrated to micro-pores by Fick’s diffusion,sliding flow,and surface diffusion.Furthermore,the CO_(2)replaced CH_(4)adsorbed by volumetric filling in micro-pores,and formed the multi-molecular layer adsorption of CO_(2).The gas pressure and migration path between CO_(2)and CH_(4)are opposite.This study can provide a theoretical basis for studying digital rock physics technology and enrich the development of CO_(2)-ECBM technology.
基金Supported by the KIST institutional program(2E26880,2E26276)
文摘X-ray imaging is the conventional method for diagnosing the orthopedic condition of a patient. Computerized Tomography(CT) scanning is another diagnostic method that provides patient’s 3D anatomical information. However, both methods have limitations when diagnosing the whole leg; X-ray imaging does not provide 3D information, and normal CT scanning cannot be performed with a standing posture. Obtaining 3D data regarding the whole leg in a standing posture is clinically important because it enables 3D analysis in the weight bearing condition.Based on these clinical needs, a hardware-based bi-plane X-ray imaging system has been developed; it uses two orthogonal X-ray images. However, such methods have not been made available in general clinics because of the hight cost. Therefore, we proposed a widely adaptive method for 2 D X-ray image and 3D CT scan data. By this method, it is possible to threedimensionally analyze the whole leg in standing posture. The optimal position that generates the most similar image is the captured X-ray image. The algorithm verifies the similarity using the performance of the proposed method by simulation-based experiments. Then, we analyzed the internal-external rotation angle of the femur using real patient data. Approximately 10.55 degrees of internal rotations were found relative to the defined anterior-posterior direction. In this paper, we present a useful registration method using the conventional X-ray image and 3D CT scan data to analyze the whole leg in the weight-bearing condition.
基金supported by the National Natural Science Foundation of China(no.51175373)the Key Technology and Development Program of the Tianjin Municipal Science and Technology Commission(no.14ZCDZGX00490)
文摘For local radiotherapy, a three-dimensional(3D)conformal localized dose planning protocol has been established in this paper to develop a precise and reasonable dose plan. A precalculated 3D dose map for a single source is obtained using the Monte Carlo method, and the spatial dose maps are combined linearly to acquire the dose distribution. The dose distribution is visualized through the real-time display of the isodose line and isodose surface combined with the reconstructed 3D organ groups. By observing 3D dose coverage to the target volume and surrounding tissues, dose planning could be initiated with greater accuracy and precision to avoid dose dead zones and excessively high-dose levels, thus achieving the 3D conformal dose planning objective. Further research into the impact that blockages have on a needle trajectory can be conducted to optimize the insertion accuracy. A treatment planning system was developed to formulate and implement the 3D local treatment plan before the surgery,during the surgery, and after the surgery. Several experiments pertaining to both single-seed and multiple-seed dose distributions were conducted to verify the accuracy of the single-seed dose calculation module and 3D superposition dose calculation in the treatment planning system.
文摘Modern radiation treatments have become fairly complex and involve in utilizing a variety of medical devices to achieve the goal of providing conformal radiation dose coverage to the tumor target(s)while maximizing the sparing of normal organ structures.Recently,different forms of linear accelerators/radioactive source based machines have been invented and developed with the aim of providing improved treatments and more treatment options.Besides linear accelerators(Linac)that have been undergoing constant improvement and advancement and can deliver fairly complicated dose distribution patterns,imaging systems,computer information and calculation systems have been more and more integrated into radiotherapy processes.To bring radiotherapy to a potentially higher level,many institutions have either acquired or started to consider particle therapy,especially proton therapy.The complexity of modern radiotherapy demands in-depth understanding of radiation physics and machine engineering as well as computer information systems.This paper is intended to provide an introductory description of radiation oncology and related procedures,and to provide an overview of the current status of medical devices in radiotherapy in the United States of America.This paper covers the radiation delivery systems,imaging systems,treatment planning systems,record and verify systems,and QA systems.
