Wu Liu, Postdoctoral Faculty Sponsor
Phase and dark field imaging with mesh-based structured illumination and polycapillary optics.
PURPOSE: X-ray phase and dark field imaging have been shown to improve the diagnostic capabilities of x-ray systems. However, these methods have found limited clinical use due to the need for multiple precision gratings with limited field of view or requirements on x-ray coherence that may not be easily translated to clinical practice. This work aims to develop a practicable x-ray phase and dark field imaging system that could be translated and practiced in the clinic.METHODS: This work employs a conventional source to create structured illumination with a simple wire mesh. A mesh-shifting algorithm is used to allow wider Fourier windowing to enhance resolution. Deconvolution of the source spot width and camera resolution improves accuracy. Polycapillary optics are employed to enhance coherence. The effects of incorporating optics with two different focal lengths are compared. Information apparent in enhanced absorption images, phase images and dark field images of fat embedded phantoms were compared and subjected to a limited ROC study. The dark field images of the moist and dry porous object (sponges) were compared.RESULTS: The mesh-based phase and dark field imaging system constructs images with three different information types: scatter free absorption images, differential phase images and scatter magnitude/dark field images, simultaneously from the same original image. The polycapillary optic enhances the coherence of the beam. The deblurring technique corrects the phase signal error due to geometrical blur and the limitation of the camera MTF and removes image artifacts to improve the resolution in a single shot. The mesh-shifting method allows the use of a wider Fourier processing window, which gives even higher resolution, at the expense of increased dose. The limited ROC study confirms the efficacy of the system over the conventional system. Dark field images of moist and dry porous object show the significance of the system in the imaging of lung infections.CONCLUSION: The mesh-based x-ray phase and dark field imaging system is an inexpensive and easy setup in terms of alignment and data acquisition and can produce phase and dark field images in a single shot with wide field of view. The system shows a significant potential use for diagnostic imaging in a clinical setting. This article is protected by copyright. All rights reserved.
View details for DOI 10.1002/mp.15247
View details for PubMedID 34554583
Dosimetry Modeling of Focused kV X-ray Radiotherapy for Wet Age-related Macular Degeneration.
Wet (neovascular) age-related macular degeneration (AMD) is the leading cause of blindness in the USA. The mainstay treatment requires monthly intravitreal injection of anti-vascular endothelial growth factor (VEGF) drugs, associated with multiple visits, high cost, and the risk of procedural injury and infection. Anti-VEGF drugs inhibit the formation of neovasculature but do not directly attack it. Radiotherapy can destroy neovasculature and potentially also inhibit wet-AMD associated inflammation and fibrosis not addressed by VEGF inhibitors. However, the current collimation-based radiotherapy device uses fixed 4 mm beams, which are prone to overtreat or undertreat the choroidal neovascularization (CNV) lesions because of their various sizes and shapes. This simulation study evaluates personalized conformal treatment with focused kV radiation using cutting-edge polycapillary x-ray optics.Simulation of the polycapillary optics was achieved via Monte Carlo (MC)-based 3D geometric ray tracing. Phase-space files modeling the focused photons were generated. The method was previously verified by phantom measurements. The ultrasmall ~0.2 mm beam focal spot perpendicular to the beam direction enables spatially fractionated grid therapy, which has been shown to preferentially damage abnormal neovascular blood vessels vs normal ones. Geant4-based MC simulations of scanning while rotating beam delivery were performed to conformally treat three clinical cases of large, medium, and small CNV lesions with regular and grid deliveries. Dose delivery uncertainties due to positioning errors were analyzed, including ±0.75 mm displacement in the three orthogonal directions and ±5° vertical/horizontal rotation of the eyeball.The simulated CNV treatments by 60 kVp focused x-ray beams show highly-conformal delivery of dose to the lesion plus margin (0.75 mm) with sharp dose fall-offs and controllable spatial modulation patterns. The 90%-10% isodose penumbra is <0.5 mm. With a 16 Gy prescription dose to the lesions, the critical structure doses are well below the tolerance. The average CNV dose varies within 10% (mostly within 4%) due to 0.75-mm linear displacements and 5-degree gaze angle rotation of the eyeball.Focused kV technique allows personalized treatment of CNV lesions and reduces unwanted radiation to adjacent healthy tissue. The simulated dose distribution is superior to currently available techniques.
View details for DOI 10.1002/mp.14404
View details for PubMedID 32683708
- Combined optic system based on polycapillary X-ray optics and single-bounce monocapillary optics for focusing X-rays from a conventional laboratory X-ray source NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2015; 802: 5-9
- Numerical design of X-ray tabletop Talbot interferometer using polycapillary optics as two-dimensional gratings with high aspect ratio OPTICS COMMUNICATIONS 2015; 356: 202-207
- Numerical design of polycapillary X-ray optics as both a focusing X-ray lens and a vacuum window VACUUM 2015; 121: 1-4
- Application of polycapillary x ray lens to eliminate both the effect of x ray source size and scatter of the sample in laboratory tomography CHINESE OPTICS LETTERS 2015; 13 (9)
- A confocal three-dimensional micro X-ray scattering technology based on Rayleigh to Compton ratio for identifying materials with similar density and different weight percentages of low-Z elements RADIATION PHYSICS AND CHEMISTRY 2015; 112: 163-168
- In situ analysis of electrocrystallization process of metal electrodeposition with confocal energy dispersive X-ray diffraction based on polycapillary X-ray optics NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2015; 785: 201-205
Application of confocal X-ray fluorescence micro-spectroscopy to the investigation of paint layers
APPLIED RADIATION AND ISOTOPES
2014; 94: 109-112
A confocal micro X-ray fluorescence (MXRF) spectrometer based on polycapillary X-ray optics was used for the identification of paint layers. The performance of the confocal MXRF was studied. Multilayered paint fragments of a car were analyzed nondestructively to demonstrate that this confocal MXRF instrument could be used in the discrimination of the various layers in multilayer paint systems.
View details for DOI 10.1016/j.apradiso.2014.07.019
View details for Web of Science ID 000345477700019
View details for PubMedID 25151613
- Measurement of grain size of polycrystalline materials with confocal energy dispersive micro-X-ray diffraction technology based on polycapillary X-ray optics NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2014; 764: 1-6
- Numerical design of in-line X-ray phase-contrast imaging based on ellipsoidal single-bounce monocapillary NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2014; 746: 33-38
- Application of confocal technology based on polycapillary X-ray optics in three-dimensional diffraction scanning analysis NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 2014; 323: 25-29
- Performance of polycapillary X-ray optics for confocal energy-dispersive small-angle X-ray scattering JOURNAL OF APPLIED CRYSTALLOGRAPHY 2013; 46: 1880-1883
- Adjustment of confocal configuration for capillary X-ray optics with a liquid secondary target NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2013; 729: 565-568
[Application of confocal micro-beam X-ray fluorescence in nondestructive scanning analysis of the distribution of elements in a single hair].
Guang pu xue yu guang pu fen xi = Guang pu
2013; 33 (11): 3147-50
The confocal micro X-ray fluorescence (XRF) based on polycapillary X-ray lens and conventional X-ray source was used to carry out the scanning analysis of the distribution of the elements in a single hair. The elemental distribution in the single hair was obtained. In the confocal micro XRF technology, the output focal spot of the polycapillary focusing X-ray lens and the input focal spot of the polycapillary parallel X-ray lens were adjusted confocally. The detector could only detect the X-rays from the overlapping foci. This confocal structure decreased the effects of the background on the X-ray spectra, and was accordingly helpful for improving the accuracy of this XRF technology. A polycapillary focusing X-ray lens with a high gain in power density was used to decrease the requirement of power of the X-ray source used in this confocal technology, and made it possible to perform such confocal micro XRF analysis by using the conventional X-ray source with low cost. Experimental results indicated that the confocal micro X-ray fluorescence based on polycapillary X-ray lens had potential applications in analyzing the elemental distribution of individual hairs.
View details for PubMedID 24555400
- Performances for confocal X-ray diffraction technology based on polycapillary slightly focusing X-ray optics NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2013; 723: 1-4