Near Real-Time X-Ray Cone-Beam Microtomography

1999 ◽  
Vol 5 (S2) ◽  
pp. 940-941
Author(s):  
Shih Ang ◽  
Wang Ge ◽  
Cheng Ping-Chin
Keyword(s):  
Reconstruction Algorithm ◽  
Cone Beam ◽  
Reconstruction Process ◽  
X Ray ◽  
Beam Geometry ◽  
Cone Beam Reconstruction ◽  
Cylindrical Coordinate ◽  
Contrast Mechanism ◽  
Penetration Ability ◽  
Set Up

Due to the penetration ability and absorption contrast mechanism, cone-beam X-ray microtomography is a powerful tool in studying 3D microstructures in opaque specimens. In contrast to the conventional parallel and fan-beam geometry, the cone-beam tomography set up is highly desirable for faster data acquisition, build-in magnification, better radiation utilization and easier hardware implementation. However, the major draw back of the cone-beam reconstruction is its computational complexity. In an effort to maximize the reconstruction speed, we have developed a generalized Feldkamp cone-beam reconstruction algorithm to optimize the reconstruction process. We report here the use of curved voxels in a cylindrical coordinate system and mapping tables to further improve the reconstruction efficiency.The generalized Feldkamp cone-beam image reconstruction algorithm is reformulated utilizing mapping table in the discrete domain as: , where .

Cone-beam 3D image reconstruction in x-ray microtomography

1993 ◽  
Vol 51 ◽  
pp. 654-655
Author(s):  
G. Wang ◽  
P. C. Cheng ◽  
T. H. Lin ◽  
D. M. Shinozaki ◽  
H. Kim
Keyword(s):  
Image Reconstruction ◽  
Point Source ◽  
Reconstruction Algorithm ◽  
Cone Beam ◽  
X Rays ◽  
Reconstruction Algorithms ◽  
X Ray ◽  
3D Image Reconstruction ◽  
Cone Beam Reconstruction ◽  
Mechanical Stage

An X-ray shadow projection microscope system using a scannable point source of X-rays is under development at AMIL-ARTS, SUNY at Buffalo, USA. The point source is generated by a focussed electron beam, which can be steered electromagnetically in a plane perpendicular to the optical axis of the microscope. A specimen is mounted on a rotatable mechanical stage for microtomography. Considering the hardware characteristics of this system and the limitations of current cone-beam reconstruction algorithms, a generalized Feldkamp’s cone-beam image reconstruction algorithm has been developed at our laboratories. In our cone-beam reconstruction, there are mainly two kinds of scanning scanning modes: planar and helix-like. A planar scanning locus is used to handle spherical or plate-like specimens. A typical case of planar scanning loci is a circle, which is used in Feldkamp’s cone-beam reconstruction. A helix-like scanning locus is used to deal with rod-shaped specimens. Without loss of generality, a locus turn of the X-ray source can be defined in cylindrical coordinates by the following equation:

scholarly journals A Method to Improve Electron Density Measurement of Cone-Beam CT Using Dual Energy Technique

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Kuo Men ◽  
Jian-Rong Dai ◽  
Ming-Hui Li ◽  
Xin-Yuan Chen ◽  
Ke Zhang ◽  
...  
Keyword(s):  
Electron Density ◽  
Cone Beam Ct ◽  
Density Measurement ◽  
Dual Energy ◽  
Cone Beam ◽  
Imaging Method ◽  
Basis Material ◽  
X Ray ◽  
Dual Energy Imaging ◽  
Set Up

Purpose. To develop a dual energy imaging method to improve the accuracy of electron density measurement with a cone-beam CT (CBCT) device.Materials and Methods. The imaging system is the XVI CBCT system on Elekta Synergy linac. Projection data were acquired with the high and low energy X-ray, respectively, to set up a basis material decomposition model. Virtual phantom simulation and phantoms experiments were carried out for quantitative evaluation of the method. Phantoms were also scanned twice with the high and low energy X-ray, respectively. The data were decomposed into projections of the two basis material coefficients according to the model set up earlier. The two sets of decomposed projections were used to reconstruct CBCT images of the basis material coefficients. Then, the images of electron densities were calculated with these CBCT images.Results. The difference between the calculated and theoretical values was within 2% and the correlation coefficient of them was about 1.0. The dual energy imaging method obtained more accurate electron density values and reduced the beam hardening artifacts obviously.Conclusion. A novel dual energy CBCT imaging method to calculate the electron densities was developed. It can acquire more accurate values and provide a platform potentially for dose calculation.

X-ray micro-CT with a displaced detector array: Application to helical cone-beam reconstruction

2003 ◽  
Vol 30 (10) ◽  
pp. 2758-2761 ◽  
Author(s):  
Vinson Liu ◽  
Nicholas R. Lariviere ◽  
Ge Wang
Keyword(s):  
Detector Array ◽  
Cone Beam ◽  
Micro Ct ◽  
X Ray ◽  
Cone Beam Reconstruction

scholarly journals An observational study of post-operative Volumetric Modulated Arc Radiotherapy (VMAT) of breast cancer by immobilizing patients on All-in-one (AIOTM) solution Breast and Lung Board without usingthermoplastic mask: Risk of collusion of gantry with couch exists if acquisition of Cone-beam Computed Tomography (CBCT)is attempted for set-up verification.

2020 ◽  
Author(s):  
Ramaiah Vinay Kumar
Keyword(s):  
Breast Cancer ◽  
Computed Tomography ◽  
Cancer Patients ◽  
Target Volume ◽  
Cone Beam ◽  
Breast Cancer Patients ◽  
Unilateral Breast Cancer ◽  
Planar Image ◽  
X Ray ◽  
Set Up

Abstract Background: Automatic Cone-beam computed tomography (CBCT) based image matching for set-up verification is recommended as compared to 2-D match for post-operative local / loco-regional radiotherapy of breast cancer patients by Volumetric Modulated Arc Therapy (VMAT) technique. However, in supine position, off-midline peripheral body Clinical Target Volume (CTV) of unilateral breast cancer patients immobilized on Breast and Lung board of All-in-One (AIO) positioning systemmay necessitate augmented movement of couch in ‘x’ and ‘z’ axis thereby raising the risk of collusion of x-ray sources / detectors system with couch. Methods and Materials: VMAT was planned by a pair of partial arc for whole target volume for seven consecutive post-operative breast cancer patients (five post-mastectomy and two post-breast conservation patients). Tattoo based set-up by shift of treatment table in x-, y- and z-axis as determined by Treatment Planning System followed by X-rays with planar image acquisition and online 2-D imaging matching was performed for set-up verification. In-room 360°rotation of x-ray source and detector system of linear accelerator (linac) was performed before x-ray planar image acquisition. Results: Completion of 360°rotation in-room of x-ray source and detector system of linacaround the machine iso-centre was not possible in six out of seven patients due to possibility of collusion of gantry with contralateral side of the couch. Conclusion: Performing CBCT for generating 3D images for computed tomography (CT) reconstruction may not be practical for patient set-up verification of post-operative radiotherapy of unilateral breast cancer patients positioned supine on breast and lung board.

A new weighting scheme for arc based circle cone-beam CT reconstruction

2021 ◽  
pp. 1-19
Author(s):  
Wei Wang ◽  
Xiang-Gen Xia ◽  
Chuanjiang He ◽  
Zemin Ren ◽  
Jian Lu
Keyword(s):  
Characteristic Function ◽  
Weighting Function ◽  
Cone Beam Ct ◽  
Reconstruction Algorithm ◽  
Cone Beam ◽  
Characteristic Functions ◽  
Projection Data ◽  
Ct Reconstruction ◽  
Scanning Angle ◽  
Beam Geometry

In this paper, we present an arc based fan-beam computed tomography (CT) reconstruction algorithm by applying Katsevich’s helical CT image reconstruction formula to 2D fan-beam CT scanning data. Specifically, we propose a new weighting function to deal with the redundant data. Our weighting function ϖ ( x _ , λ ) is an average of two characteristic functions, where each characteristic function indicates whether the projection data of the scanning angle contributes to the intensity of the pixel x _ . In fact, for every pixel x _ , our method uses the projection data of two scanning angle intervals to reconstruct its intensity, where one interval contains the starting angle and another contains the end angle. Each interval corresponds to a characteristic function. By extending the fan-beam algorithm to the circle cone-beam geometry, we also obtain a new circle cone-beam CT reconstruction algorithm. To verify the effectiveness of our method, the simulated experiments are performed for 2D fan-beam geometry with straight line detectors and 3D circle cone-beam geometry with flat-plan detectors, where the simulated sinograms are generated by the open-source software “ASTRA toolbox.” We compare our method with the other existing algorithms. Our experimental results show that our new method yields the lowest root-mean-square-error (RMSE) and the highest structural-similarity (SSIM) for both reconstructed 2D and 3D fan-beam CT images.

Reconstruction Algorithm of Cone-Beam Phase X-Ray Computer-Tomography Based on Grating Imaging

2008 ◽  
Vol 28 (6) ◽  
pp. 1079-1084
Author(s):  
陈欣 Chen Xin ◽  
孙怡 Sun Yi ◽  
朱佩平 Zhu Peiping
Keyword(s):  
Computer Tomography ◽  
Reconstruction Algorithm ◽  
Cone Beam ◽  
X Ray
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