Mammography is the primary imaging tool for screening and diagnosis of human breast cancers, but ∼10-20% of palpable tumors are not detectable on mammograms and only about 40% of biopsied lesions are malignant. Here we report a high-resolution, low-dose phase contrast X-ray tomographic method for 3D diagnosis of human breast cancers. By combining phase contrast X-ray imaging with an image reconstruction method known as equally sloped tomography, we imaged a human breast in three dimensions and identified a malignant cancer with a pixel size of 92 μm and a radiation dose less than that of dual-view mammography. According to a blind evaluation by five independent radiologists, our method can reduce the radiation dose and acquisition time by ∼74% relative to conventional phase contrast X-ray tomography, while maintaining high image resolution and image contrast. These results demonstrate that high-resolution 3D diagnostic imaging of human breast cancers can, in principle, be performed at clinical compatible doses.radiation dose reduction | iterative algorithm | analyzer based imaging M ammography is a widely used imaging technique for early detection of human breast cancers. Although more advanced technologies such as digital mammography have been developed to improve its image quality (1), there are three potential risks associated with mammography. First, mammograms miss up to 20% of breast cancers that are present during the time of screening (2). Second, in some cases mammograms appear abnormal, but no breast cancers are actually present (3). Third, repeated mammography examinations have the potential of causing cancers (4). Dedicated breast computed tomography (CT) can reduce some of these risks, but its spatial resolution (∼400 μm) is mainly limited by the X-ray dose deliverable to the radiationsensitive human breast and its detection of microcalcifications is inferior to mammography (5). Furthermore, some tumors are not visible in CT because its image contrast is based on the X-ray absorption coefficient and is intrinsically low between tumors and normal tissues. A very promising approach to significantly improve the image resolution, image contrast and detectability is the use of phase contrast x-ray tomography (PCT) (6-8) (Materials and Methods). Compared with absorption-based CT, PCT is sensitive to the refraction (i.e., "phase shift") of X-rays in matter. In soft tissues, phase variations can be two to three orders of magnitude larger than the absorption ones (9), and thus an increased image contrast can be achieved. Over the past few decades, phase contrast X-ray imaging has been under rapid development and various X-ray phase contrast methods have been implemented, including X-ray interferometry (6, 7), analyzer-based (or diffraction-enhanced) imaging (10, 11), propagation-based imaging (12, 13), grating-based imaging (14, 15), and grating noninterferometric methods (16). A large number of X-ray phase contrast imaging results has been reported on both technical developments and biomedical applications ...
Ultrabroadband self-phase-stabilized near-IR pulses have been generated by difference-frequency generation of a filament broadened supercontinuum followed by two-stage optical parametric amplification. Pulses with energy up to 1.2 mJ and duration down to 17 fs are demonstrated. These characteristics make such a source suited as a driver for high-order harmonic generation and isolated attosecond pulse production.
The gold standard method for visualizing the pathologies underlying human sensorineural hearing loss has remained post-mortem histology for over 125 years, despite awareness that histological preparation induces severe artifacts in biological tissue. Historically, the transition from post-mortem assessment to non-invasive clinical biomedical imaging in living humans has revolutionized diagnosis and treatment of disease; however, innovation in non-invasive techniques for cellular-level intracochlear imaging in humans has been difficult due to the cochlea's small size, complex 3D configuration, fragility, and deep encasement within bone. Here we investigate the ability of synchrotron radiation-facilitated X-ray absorption and phase contrast imaging to enable visualization of sensory cells and nerve fibers in the cochlea's sensory epithelium in situ in 3D intact, non-decalcified, unstained human temporal bones. Our findings show that this imaging technique resolves the bone-encased sensory epithelium's cytoarchitecture with unprecedented levels of cellular detail for an intact, unstained specimen, and is capable of distinguishing between healthy and damaged epithelium. All analyses were performed using commercially available software that quickly reconstructs and facilitates 3D manipulation of massive data sets. Results suggest that synchrotron radiation phase contrast imaging has the future potential to replace histology as a gold standard for evaluating intracochlear structural integrity in human specimens, and motivate further optimization for translation to the clinic.
The spatiotemporal effects generated in the wake of a laser filament propagating in nitrogen are investigated. At suitable time delays, a probe light pulse propagating along the wake experiences a strong spatial confinement and a noticeable spectral broadening at the same time. Numerical simulations, well reproducing the experimental findings, show the key role of the impulsive rotational Raman response in the observed phenomena.
Phase-contrast imaging CT may facilitate a more complete evaluation of the human knee joint by providing concurrent comprehensive information about cartilage, the underlying subchondral bone, and their changes in osteoarthritic conditions.
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