Multisource inverse-geometry CT. Part I. System concept and development

Man, Bruno De; Uribe, J.; Baek, Jongduk; Harrison, Daniel; Yin, Zhye; Longtin, Randy; Roy, Jaydeep; Waters, Bill; Wilson, Chris; Short, Jonathan; Inzinna, Lou; Reynolds, Joseph; Neculaes, V.B.; Frutschy, Kristopher; Senzig, Bob; Pelc, Norbert J.

doi:10.1118/1.4954846

Cited by 10 publications

(8 citation statements)

References 31 publications

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“…Furthermore, more than 80% of the emitted current in the multisource configuration reaches the target to provide the required x-ray flux relevant for the imaging tasks detailed in the companion system article. 24 We have successfully utilized DCEs in our multisource prototype. Emission stability for these emitters at high current densities is a critical metric for potential implementation in future clinical systems.…”

Section: Discussionmentioning

confidence: 99%

“…Simultaneous optimization of all of these goals would produce the best x-ray source for the IGCT system. 24 A grounded cathode design was chosen to avoid having to operate the electron beam switching circuits at high potential relative to ground-unlike traditional x-ray tubes, which either operate anode grounded or with the anode and cathode each at half of the total voltage. An initially built concept utilized a segmented anode with tungsten bars brazed onto copper blocks (Fig.…”

Section: A Initially Built Distributed Source Conceptmentioning

confidence: 99%

“…System benefits of the virtual bowtie are described in a companion system article. 24 The oscilloscope screen shot captures for clarity only the mesh grid voltages (∼380-470 V) for the 32 emitters. Each grid voltage pulse was 100 µs long, with 750 µs between x-ray pulses from each emitter.…”

Section: Electron Gun Electronics and Controlmentioning

confidence: 99%

“…We have previously shown that CT systems using distributed ("multi") sources can extend axial coverage while mitigating cone-beam artifacts and reduce the dose compared to conventional CT systems. 24 Figure 1 shows the x-ray distributed source demonstrated here for inverse-geometry CT.…”

Section: Introductionmentioning

confidence: 99%

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Multisource inverse-geometry CT. Part II. X-ray source design and prototype

et al. 2016

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Purpose: This paper summarizes the development of a high-power distributed x-ray source, or "multisource," designed for inverse-geometry computed tomography (CT) applications [see B. De Man et al., "Multisource inverse-geometry CT. Part I. System concept and development," Med. Phys. 43, 4607-4616 (2016)]. The paper presents the evolution of the source architecture, component design (anode, emitter, beam optics, control electronics, high voltage insulator), and experimental validation. Methods: Dispenser cathode emitters were chosen as electron sources. A modular design was adopted, with eight electron emitters (two rows of four emitters) per module, wherein tungsten targets were brazed onto copper anode blocks-one anode block per module. A specialized ceramic connector provided high voltage standoff capability and cooling oil flow to the anode. A matrix topology and low-noise electronic controls provided switching of the emitters. Results: Four modules (32 x-ray sources in two rows of 16) have been successfully integrated into a single vacuum vessel and operated on an inverse-geometry computed tomography system. Dispenser cathodes provided high beam current (>1000 mA) in pulse mode, and the electrostatic lenses focused the current beam to a small optical focal spot size (0.5 × 1.4 mm). Controlled emitter grid voltage allowed the beam current to be varied for each source, providing the ability to modulate beam current across the fan of the x-ray beam, denoted as a virtual bowtie filter. The custom designed controls achieved x-ray source switching in <1 µs. The cathode-grounded source was operated successfully up to 120 kV. Conclusions: A high-power, distributed x-ray source for inverse-geometry CT applications was successfully designed, fabricated, and operated. Future embodiments may increase the number of spots and utilize fast read out detectors to increase the x-ray flux magnitude further, while still staying within the stationary target inherent thermal limitations. C 2016 American Association of Physicists in Medicine. [http://dx

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Section: Discussionmentioning

confidence: 99%

Section: A Initially Built Distributed Source Conceptmentioning

confidence: 99%

Section: Electron Gun Electronics and Controlmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multisource inverse-geometry CT. Part II. X-ray source design and prototype

et al. 2016

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“…An inverse geometry fan‐beam CT system has been developed in which a long source array and a small detector array were used to cover the reconstruction FOV 8 . A major advantage of the inverse fan beam CT is that each X‐ray beam intensity can be dynamically modulated based on body shape so that the X‐ray exposure can be optimized 9,10 . But it would require a high tube power that cannot be achieved with the fixed anode tube design 11 .…”

Section: Introductionmentioning

confidence: 99%

Tetrahedron beam imaging with a multi‐pixel thermionic emission X‐ray source and a photon‐counting detector: A benchtop experimental study

et al. 2021

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A tetrahedron beam (TB) X-ray system with a linear X-ray source array and a linear detector array positioned orthogonal to each other may overcome the X-ray scattering problem of traditional cone-beam X-ray systems. We developed a TB imaging benchtop system using a linear array X-ray source to demonstrate the principle and benefits of TB imaging. Methods: A multi-pixel thermionic emission X-ray (MPTEX) source with 48 focal spots in 4-mm spacing was developed in-house. The X-ray beams are collimated to a stack of fan beams that are converged to a 6-mm wide multi-row photon-counting detector (PCD). The data collected with a sequential scan of the sources at a fixed view angle were synthesized to a 2D radiography image by a shift-and-add algorithm. The data collected with a full rotation of the system were reconstructed into 3D TB CT (TBCT) images using an Feldkamp, Davis, and Kress (FDK)-based computed tomography (CT) algorithm modified for the TB geometry. Results: With an 18.8-cm long source array and a 35-cm long detector array,the TB benchtop system provides a 25-cm cross-sectional and 8-cm axial field of view (FOV). The scatter-to-primary ratio (SPR) was approximately 17% for TB, as compared with 120% for cone beam geometry. The TBCT system enables reconstructions in two-dimensional radiography and three-dimensional volumetric CT. The TBCT images were free of "cupping" artifacts and have similar image quality as diagnostic helical CT. Conclusions: A TB imaging benchtop imaging system was successfully developed with MPTEX source and PCD. Phantom and animal cadaver imaging demonstrated that the TB system can produce satisfactory radiographic X-ray images and 3D CT images with image quality comparable to diagnostic helical CTs. K E Y W O R D Smulti-pixel thermionic emission X-ray source, photon-counting detector, scatter-to-primary ratio, tetrahedron beam

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A simulated comparison of lung tumor target verification using stereoscopic tomosynthesis or radiography

Hsieh

Cao

et al. 2022

Medical Physics

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Purpose Mobile lung tumors are increasingly being treated with ablative radiotherapy, for which precise motion management is essential. In‐room stereoscopic radiography systems are able to guide ablative radiotherapy for stationary cranial lesions but not optimally for lung tumors unless fiducial markers are inserted. We propose augmenting stereoscopic radiographic systems with multiple small x‐ray sources to provide the capability of imaging with stereoscopic, single frame tomosynthesis. Methods In single frame tomosynthesis, nine x‐ray sources are placed in a 3 × 3 configuration and energized simultaneously. The beams from these sources are collimated so that they converge on the tumor and then diverge to illuminate nine non‐overlapping sectors on the detector. These nine sector images are averaged together and filtered to create the tomosynthesis effect. Single frame tomosynthesis is intended to be an alternative imaging mode for existing stereoscopic systems with a field of view that is three times smaller and a temporal resolution equal to the frame rate of the detector. We simulated stereoscopic tomosynthesis and radiography using Monte Carlo techniques on 60 patients with early‐stage lung cancer from the NSCLC‐Radiomics dataset. Two board‐certified radiation oncologists reviewed these simulated images and rated them on a 4‐point scale (1: tumor not visible; 2: tumor visible but inadequate for motion management; 3: tumor visible and adequate for motion management; 4: tumor visibility excellent). Each tumor was independently presented four times (two viewing angles from radiography and two viewing angles from tomosynthesis) in a blinded fashion over two reading sessions. Results The fraction of tumors that were rated as adequate or excellent for motion management (scores 3 or 4) from at least one viewing angle was 53% using radiography and 90% using tomosynthesis. From both viewing angles, the corresponding fractions were 7% for radiography and 48% for tomosynthesis. Readers agreed exactly on 62% of images and within 1 point on 98% of images. The acquisition technique was estimated to be 75 mAs at 120 kVp per treatment fraction assuming one verification image per breath, approximately one order of magnitude less than a standard dose cone beam CT. Conclusions Stereoscopic tomosynthesis may provide a noninvasive, low dose, intrafraction motion verification technique for lung tumors treated by ablative radiotherapy. The system architecture is compatible with real‐time video capture at 30 frames per second. Simulations suggest that most, but not all, lung tumors can be adequately visualized from at least one viewing angle.

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Multisource inverse-geometry CT. Part I. System concept and development

Cited by 10 publications

References 31 publications

Multisource inverse-geometry CT. Part II. X-ray source design and prototype

Multisource inverse-geometry CT. Part II. X-ray source design and prototype

Tetrahedron beam imaging with a multi‐pixel thermionic emission X‐ray source and a photon‐counting detector: A benchtop experimental study

A simulated comparison of lung tumor target verification using stereoscopic tomosynthesis or radiography

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