DEBISim: A simulation pipeline for dual energy CT-based baggage inspection systems1

2021 ◽  
Vol 29 (2) ◽  
pp. 259-285
Author(s):  
Ankit Manerikar ◽  
Fangda Li ◽  
Avinash C. Kak
Keyword(s):  
Simulated Data ◽  
Dual Energy ◽  
Cone Beam ◽  
Dual Energy Ct ◽  
Software Pipeline ◽  
Security Screening ◽  
X Ray ◽  
Baggage Screening ◽  
End To End

BACKGROUND: Materials characterization made possible by dual energy CT (DECT) scanners is expected to considerably improve automatic detection of hazardous objects in checked and carry-on luggage at our airports. Training a computer to identify the hazardous items from DECT scans however implies training on a baggage dataset that can represent all the possible ways a threat item can packed inside a bag. Practically, however, generating such data is made challenging by the logistics (and the permissions) related to the handling of the hazardous materials. OBJECTIVE: The objective of this study is to present a software simulation pipeline that eliminates the need for a human to handle dangerous materials and that allows for virtually unlimited variability in the placement of such materials in a bag alongside benign materials. METHODS: In this paper, we present our DEBISim software pipeline that carries out an end-to-end simulation of a DECT scanner for virtual bags. The key highlights of DEBISim are: (i) A 3D user-interactive graphics editor for constructing a virtual 3D bag with manual placement of different types of objects in it; (ii) An automated virtual bag generation algorithm for creating randomized baggage datasets; (iii) An ability to spawn deformable sheets and liquid-filled containers in a virtual bag to represent plasticized and liquid explosives; and (iv) A GPU-based X-ray forward modelling block for spiral cone-beam scanners used in checked baggage screening. RESULTS: We have tested our simulator using two standard CT phantoms: the American College of Radiology (ACR) phantom and the NIST security screening phantom as well as on a set of reference materials representing commonly encountered items in checked baggage. For these phantoms, we have assessed the quality of the simulator by comparing the simulated data reconstructions with real CT scans of the same phantoms. The comparison shows that the material-specific properties as well as the CT artifacts in the scans generated by DEBISim are close to those produced by an actual scanner. CONCLUSION: DEBISim is an end-to-end simulation framework for rapidly generating X-ray baggage data for dual energy cone-beam scanners.

Material Identification in Presence of Metal for Baggage Screening

2020 ◽  
Vol 2020 (14) ◽  
pp. 294-1-294-8
Author(s):  
Sandamali Devadithya ◽  
David Castañón
Keyword(s):  
Atomic Number ◽  
Effective Atomic Number ◽  
Simulated Data ◽  
Dual Energy ◽  
Basis Functions ◽  
Total Variation Regularization ◽  
Ct Scanner ◽  
Edge Preserving ◽  
Baggage Screening ◽  
Dual Energy Imaging

Dual-energy imaging has emerged as a superior way to recognize materials in X-ray computed tomography. To estimate material properties such as effective atomic number and density, one often generates images in terms of basis functions. This requires decomposition of the dual-energy sinograms into basis sinograms, and subsequently reconstructing the basis images. However, the presence of metal can distort the reconstructed images. In this paper we investigate how photoelectric and Compton basis functions, and synthesized monochromatic basis (SMB) functions behave in the presence of metal and its effect on estimation of effective atomic number and density. Our results indicate that SMB functions, along with edge-preserving total variation regularization, show promise for improved material estimation in the presence of metal. The results are demonstrated using both simulated data as well as data collected from a dualenergy medical CT scanner.

A Spectrum-Adaptive Decomposition Method for Effective Atomic Number Estimation Using Dual Energy CT

2020 ◽  
Vol 2020 (14) ◽  
pp. 293-1-293-7
Author(s):  
Ankit Manerikar ◽  
Fangda Li ◽  
Avinash C. Kak
Keyword(s):  
Atomic Number ◽  
Decomposition Method ◽  
Traditional Approach ◽  
Effective Atomic Number ◽  
Dual Energy ◽  
Performance Comparison ◽  
Estimation Methods ◽  
Dual Energy Ct ◽  
Projection Data ◽  
X Ray

Dual Energy Computed Tomography (DECT) is expected to become a significant tool for voxel-based detection of hazardous materials in airport baggage screening. The traditional approach to DECT imaging involves collecting the projection data using two different X-ray spectra and then decomposing the data thus collected into line integrals of two independent characterizations of the material properties. Typically, one of these characterizations involves the effective atomic number (Zeff) of the materials. However, with the X-ray spectral energies typically used for DECT imaging, the current best-practice approaches for dualenergy decomposition yield Zeff values whose accuracy range is limited to only a subset of the periodic-table elements, more specifically to (Z < 30). Although this estimation can be improved by using a system-independent ρe — Ze (SIRZ) space, the SIRZ transformation does not efficiently model the polychromatic nature of the X-ray spectra typically used in physical CT scanners. In this paper, we present a new decomposition method, AdaSIRZ, that corrects this shortcoming by adapting the SIRZ decomposition to the entire spectrum of an X-ray source. The method reformulates the X-ray attenuation equations as direct functions of (ρe, Ze) and solves for the coefficients using bounded nonlinear least-squares optimization. Performance comparison of AdaSIRZ with other Zeff estimation methods on different sets of real DECT images shows that AdaSIRZ provides a higher output accuracy for Zeff image reconstructions for a wider range of object materials.

scholarly journals Metal artefact reduction of different alloys with dual energy computed tomography (DECT)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anand John Vellarackal ◽  
Achim Hermann Kaim
Keyword(s):  
Stainless Steel ◽  
Image Quality ◽  
Femoral Stem ◽  
Dual Energy ◽  
Dual Energy Ct ◽  
Bony Tissue ◽  
Stem Image ◽  
Metal Artefact ◽  
Artefact Reduction

AbstractTo evaluate the influence of dual-energy CT (DECT) and Virtual monochromatic spectral (VMS) imaging on: (1) the artefact size of geometrically identical orthopaedic implants consisting of three different compositions and (2) the image quality of the surrounding bone, three similar phantoms—each featuring one femoral stem composed of either titanium, chrome-cobalt or stainless steel surrounded by five calcium pellets (200 mg hydroxyapatite/calcium carbonate) to simulate bony tissue and one reference pellet located away from the femoral stem—were built. DECT with two sequential scans (80 kVp and 140 kVp; scan-to-scan technique) was performed, and VMS images were calculated between 40 and 190 keV. The artefact sizes were measured volumetrically by semiautomatic selection of regions of interest (ROIs), considering the VMS energies and the polychromatic spectres. Moreover, density and image noise within the pellets were measured. All three phantoms exhibit artefact size reduction as energy increases from 40 to 190 keV. Titanium exhibited a stronger reduction than chrome-cobalt and stainless steel. The artefacts were dependent on the diameter of the stem. Image quality increases with higher energies on VMS with a better depiction of surrounding structures. Monoenergetic energies 70 keV and 140 keV demonstrate superior image quality to those produced by spectral energies 80 kVp and 140 kVp.

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.

Image Quality of Iodine Maps for Pulmonary Embolism: A Comparison of Subtraction CT and Dual-Energy CT

2019 ◽  
Vol 212 (6) ◽  
pp. 1253-1259 ◽  
Author(s):  
Dagmar Grob ◽  
Ewoud Smit ◽  
Luuk J. Oostveen ◽  
Miranda M. Snoeren ◽  
Mathias Prokop ◽  
...  
Keyword(s):  
Pulmonary Embolism ◽  
Image Quality ◽  
Dual Energy ◽  
Dual Energy Ct ◽  
Iodine Maps

Assessment of Local Bone Quality of the Distal Radius Using a Novel Hard Tissue Diagnostic Instrument

2009 ◽  
Author(s):  
Christina Salas ◽  
Meir Marmor ◽  
Thomas Chu ◽  
Paul Hansma ◽  
Amir Matityahu ◽  
...  
Keyword(s):  
Gold Standard ◽  
Bone Matrix ◽  
Dual Energy ◽  
Hard Tissue ◽  
Mineral Density ◽  
X Ray ◽  
Local Bone ◽  
Implant Selection ◽  
Skeletal Disorder

Senile osteoporosis has been defined as a skeletal disorder characterized by a deterioration of bone matrix with an increase in susceptibility to fracture with increasing age (1). Studies have shown that over 25 million Americans are currently afflicted with osteoporosis and/or osteopoenia, with this number doubling by 2020. (2) (3) With the propensity for fracture being large in older osteoporotic patients, quantification of bone mineral density (BMD) is essential for proper implant selection in the event of a fracture. Dual energy x-ray absorptiometry (DEXA) is the clinical gold standard for BMD assessment; however, the hardware associated with this technique is neither portable nor appropriate for intraoperative use, and both of these qualities are occasionally necessary clinically.

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