Aim To investigate the relationship between the positioning of the lower central incisor and physical morphology of the surrounding alveolar bone. Methodology Thirty-eight patients (18 males, 20 females), with mean ag...Aim To investigate the relationship between the positioning of the lower central incisor and physical morphology of the surrounding alveolar bone. Methodology Thirty-eight patients (18 males, 20 females), with mean age of 13.4 years, were included in this study. As part of orthodontic treatment planning the patients were required to take dental Cone-beam CT (CBCT) covering the region of lower incisors, the surrounding alveolar bone and the mandibular symphysis. The cephalometric parameters were designed and measured to indicate the inclination of lower central incisor and physical morphology of the adjacent alveolar bone. Computer-aided descriptive statistical analysis was performed using SPSS 15.0 software package for Windows. A correlation analysis and a linear regression analysis between the incisor inclination and the alveolar bone morphology were performed. Results Significant positive correlations were found between the lower central incisor inclination and the morphological contour of the alveolar bone (P<0.05). The lower central incisor root apex was closer to the lingual alveolar crest when it was buccally inclined. Conclusion The morphology of the alveolar bone may be affected by incisal inclination.展开更多
Because of the growing concern over the radiation dose delivered to patients, X-ray cone-beam CT(CBCT) imaging of low dose is of great interest. It is difficult for traditional reconstruction methods such as Feldkamp ...Because of the growing concern over the radiation dose delivered to patients, X-ray cone-beam CT(CBCT) imaging of low dose is of great interest. It is difficult for traditional reconstruction methods such as Feldkamp to reduce noise and keep resolution at low doses. A typical method to solve this problem is using optimizationbased methods with careful modeling of physics and additional constraints. However, it is computationally expensive and very time-consuming to reach an optimal solution. Recently, some pioneering work applying deep neural networks had some success in characterizing and removing artifacts from a low-dose data set. In this study,we incorporate imaging physics for a cone-beam CT into a residual convolutional neural network and propose a new end-to-end deep learning-based method for slice-wise reconstruction. By transferring 3D projection to a 2D problem with a noise reduction property, we can not only obtain reconstructions of high image quality, but also lower the computational complexity. The proposed network is composed of three serially connected sub-networks: a cone-to-fan transformation sub-network, a 2D analytical inversion sub-network, and an image refinement sub-network. This provides a comprehensive solution for end-to-end reconstruction for CBCT. The advantages of our method are that the network can simplify a 3D reconstruction problem to a 2D slice-wise reconstruction problem and can complete reconstruction in an end-to-end manner with the system matrix integrated into the network design. Furthermore, reconstruction can be less computationally expensive and easily parallelizable compared with iterative reconstruction methods.展开更多
This study was aimed at developing an efficient simulation technique with an ordinary PC.The work involved derivation of mathematical operators,analytic phantom generations,and effective analytical projectors developi...This study was aimed at developing an efficient simulation technique with an ordinary PC.The work involved derivation of mathematical operators,analytic phantom generations,and effective analytical projectors developing for cone-beam CT and pinhole SPECT imaging.The computer simulations based on the analytical projectors were developed by ray-tracing method for cone-beam CT and voxel-driven method for pinhole SPECT of degrading blurring.The 3D Shepp-Logan,Jaszczak and Defrise phantoms were used for simulation evaluations and image reconstructions.The reconstructed phantom images were of good accuracy with the phantoms.The results showed that the analytical simulation technique is an efficient tool for studying cone-beam CT and pinhole SPECT imaging.展开更多
In helical cone-beam computed tomography(CT), Feldkamp-Davis-Kress(FDK) based image reconstruction algorithms are by far the most popular. However, artifacts are commonly met in the presence of lateral projection trun...In helical cone-beam computed tomography(CT), Feldkamp-Davis-Kress(FDK) based image reconstruction algorithms are by far the most popular. However, artifacts are commonly met in the presence of lateral projection truncation. The reason is that the ramp filter is global. To restrain the truncation artifacts, an approximate reconstruction formula is proposed based on the Derivative-Hilbert-Backprojection(DHB) framework. In the method, the first order derivative filter is followed by the Hilbert transform. Since the filtered projection values are almost zero by the first order derivative filter, the following Hilbert transform has little influence on the projection values, even though the projections are laterally truncated. The proposed method has two main advantages. First, it has comparable computational efficiency and image quality as well as the conventional helical FDK algorithm for non-truncated projections. The second advantage is that images can be reconstructed with acceptable quality and much lower computational cost in comparison to the Laplace operator based algorithm in cases with truncated projections. To point out the advantages of our method, simulations on the computer and real data experiments on our laboratory industrial cone-beam CT are conducted. The simulated and experimental results demonstrate that the method is feasible for image reconstruction in the case of projection truncation.展开更多
<strong>Purpose: </strong><span><span style="font-family:""><span style="font-family:Verdana;">Verified the delivered dose distribution of lung cancer Stereotacti...<strong>Purpose: </strong><span><span style="font-family:""><span style="font-family:Verdana;">Verified the delivered dose distribution of lung cancer Stereotactic </span><span><span style="font-family:Verdana;">Body Radiotherapy (SBRT) using the cone-beam CT images. </span><b><span style="font-family:Verdana;">Methods:</span></b></span><b> </b><span style="font-family:Verdana;">Twenty </span><span style="font-family:Verdana;">lung cancer patients </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">who </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">underwent SBRT with 100 CBCT images were</span></span><span><span style="font-family:""> <span style="font-family:Verdana;">enrolled in this study. Delivered dose distributions were recalculated on</span><span style="font-family:Verdana;"> CBCT images with </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span><span><span style="font-family:""><span style="font-family:Verdana;">deformed and non-deformed metho</span><span style="font-family:Verdana;">d</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span><span><span style="font-family:""><span style="font-family:Verdana;">, respectively. The </span><span style="font-family:Verdana;">planned and delivered dose distributions were compared using the</span><span style="font-family:Verdana;"> dose-volume histograms. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">The delivered target coverage (V100) per patient inside target volume deviated on average were 0.83% ± 0.86% and 1.38% ±</span></span></span><span><span style="font-family:""> </span></span><span><span style="font-family:""><span style="font-family:Verdana;">1.40% for Pct </span><i><span style="font-family:Verdana;">vs</span></i><span style="font-family:Verdana;">. Pcbct and Pct </span><i><span style="font-family:Verdana;">vs</span></i><span style="font-family:Verdana;">. Pdcbct, respectively. The Conformity Index (CI) and Gradient Index (GI) showed a good agreement among the plans. For the critical organs, only minor differences were observed between the planned dose and </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span><span><span style="font-family:""><span style="font-family:Verdana;">delivered dose. </span><b><span style="font-family:Verdana;">Conclusions: </span></b><span style="font-family:Verdana;">CBCT images were </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">a </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">useful tool for setup and dose deliver</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">y</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"> verification for lung cancer patients </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">who </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">underwent SBRT.</span></span>展开更多
文摘Aim To investigate the relationship between the positioning of the lower central incisor and physical morphology of the surrounding alveolar bone. Methodology Thirty-eight patients (18 males, 20 females), with mean age of 13.4 years, were included in this study. As part of orthodontic treatment planning the patients were required to take dental Cone-beam CT (CBCT) covering the region of lower incisors, the surrounding alveolar bone and the mandibular symphysis. The cephalometric parameters were designed and measured to indicate the inclination of lower central incisor and physical morphology of the adjacent alveolar bone. Computer-aided descriptive statistical analysis was performed using SPSS 15.0 software package for Windows. A correlation analysis and a linear regression analysis between the incisor inclination and the alveolar bone morphology were performed. Results Significant positive correlations were found between the lower central incisor inclination and the morphological contour of the alveolar bone (P<0.05). The lower central incisor root apex was closer to the lingual alveolar crest when it was buccally inclined. Conclusion The morphology of the alveolar bone may be affected by incisal inclination.
基金supported by the National Natural Science Foundation of China(Nos.61771279,11435007)the National Key Research and Development Program of China(No.2016YFF0101304)
文摘Because of the growing concern over the radiation dose delivered to patients, X-ray cone-beam CT(CBCT) imaging of low dose is of great interest. It is difficult for traditional reconstruction methods such as Feldkamp to reduce noise and keep resolution at low doses. A typical method to solve this problem is using optimizationbased methods with careful modeling of physics and additional constraints. However, it is computationally expensive and very time-consuming to reach an optimal solution. Recently, some pioneering work applying deep neural networks had some success in characterizing and removing artifacts from a low-dose data set. In this study,we incorporate imaging physics for a cone-beam CT into a residual convolutional neural network and propose a new end-to-end deep learning-based method for slice-wise reconstruction. By transferring 3D projection to a 2D problem with a noise reduction property, we can not only obtain reconstructions of high image quality, but also lower the computational complexity. The proposed network is composed of three serially connected sub-networks: a cone-to-fan transformation sub-network, a 2D analytical inversion sub-network, and an image refinement sub-network. This provides a comprehensive solution for end-to-end reconstruction for CBCT. The advantages of our method are that the network can simplify a 3D reconstruction problem to a 2D slice-wise reconstruction problem and can complete reconstruction in an end-to-end manner with the system matrix integrated into the network design. Furthermore, reconstruction can be less computationally expensive and easily parallelizable compared with iterative reconstruction methods.
基金Supported by National Natural Science Foundation of China(10875162)
文摘This study was aimed at developing an efficient simulation technique with an ordinary PC.The work involved derivation of mathematical operators,analytic phantom generations,and effective analytical projectors developing for cone-beam CT and pinhole SPECT imaging.The computer simulations based on the analytical projectors were developed by ray-tracing method for cone-beam CT and voxel-driven method for pinhole SPECT of degrading blurring.The 3D Shepp-Logan,Jaszczak and Defrise phantoms were used for simulation evaluations and image reconstructions.The reconstructed phantom images were of good accuracy with the phantoms.The results showed that the analytical simulation technique is an efficient tool for studying cone-beam CT and pinhole SPECT imaging.
基金Supported by the National High Technology Research and Development Program of China(No.2012AA011603)National Nature Science Foundation of China(No.61372172)
文摘In helical cone-beam computed tomography(CT), Feldkamp-Davis-Kress(FDK) based image reconstruction algorithms are by far the most popular. However, artifacts are commonly met in the presence of lateral projection truncation. The reason is that the ramp filter is global. To restrain the truncation artifacts, an approximate reconstruction formula is proposed based on the Derivative-Hilbert-Backprojection(DHB) framework. In the method, the first order derivative filter is followed by the Hilbert transform. Since the filtered projection values are almost zero by the first order derivative filter, the following Hilbert transform has little influence on the projection values, even though the projections are laterally truncated. The proposed method has two main advantages. First, it has comparable computational efficiency and image quality as well as the conventional helical FDK algorithm for non-truncated projections. The second advantage is that images can be reconstructed with acceptable quality and much lower computational cost in comparison to the Laplace operator based algorithm in cases with truncated projections. To point out the advantages of our method, simulations on the computer and real data experiments on our laboratory industrial cone-beam CT are conducted. The simulated and experimental results demonstrate that the method is feasible for image reconstruction in the case of projection truncation.
文摘<strong>Purpose: </strong><span><span style="font-family:""><span style="font-family:Verdana;">Verified the delivered dose distribution of lung cancer Stereotactic </span><span><span style="font-family:Verdana;">Body Radiotherapy (SBRT) using the cone-beam CT images. </span><b><span style="font-family:Verdana;">Methods:</span></b></span><b> </b><span style="font-family:Verdana;">Twenty </span><span style="font-family:Verdana;">lung cancer patients </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">who </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">underwent SBRT with 100 CBCT images were</span></span><span><span style="font-family:""> <span style="font-family:Verdana;">enrolled in this study. Delivered dose distributions were recalculated on</span><span style="font-family:Verdana;"> CBCT images with </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span><span><span style="font-family:""><span style="font-family:Verdana;">deformed and non-deformed metho</span><span style="font-family:Verdana;">d</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span><span><span style="font-family:""><span style="font-family:Verdana;">, respectively. The </span><span style="font-family:Verdana;">planned and delivered dose distributions were compared using the</span><span style="font-family:Verdana;"> dose-volume histograms. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">The delivered target coverage (V100) per patient inside target volume deviated on average were 0.83% ± 0.86% and 1.38% ±</span></span></span><span><span style="font-family:""> </span></span><span><span style="font-family:""><span style="font-family:Verdana;">1.40% for Pct </span><i><span style="font-family:Verdana;">vs</span></i><span style="font-family:Verdana;">. Pcbct and Pct </span><i><span style="font-family:Verdana;">vs</span></i><span style="font-family:Verdana;">. Pdcbct, respectively. The Conformity Index (CI) and Gradient Index (GI) showed a good agreement among the plans. For the critical organs, only minor differences were observed between the planned dose and </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span><span><span style="font-family:""><span style="font-family:Verdana;">delivered dose. </span><b><span style="font-family:Verdana;">Conclusions: </span></b><span style="font-family:Verdana;">CBCT images were </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">a </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">useful tool for setup and dose deliver</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">y</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"> verification for lung cancer patients </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">who </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">underwent SBRT.</span></span>
