PubMed · 13358605
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D M ANGEVINE. 1956. Connective tissue.. https://pubmed.ncbi.nlm.nih.gov/13358605/
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Monochromatic x-ray computed tomography (CT) at two different energies provides information about electron density of human tissue without ambiguity due to the beam hardening effect. This information makes the treatment planning for proton and heavy-ion radiotherapy more precise. We have started a feasibility study on dual energy x-ray CT by using synchrotron radiation. A translation-rotation scanning CT system was developed for quantitative measurement in order to clarify what precision in the measurement was achieved. Liquid samples of solutions of K2HPO4 and solid samples of tissue equivalent materials were used to simulate human tissue. The experiments were carried out using monochromatic x-rays with energies of 40, 70 and 80 keV produced by monochromatizing synchrotron radiation. The solid samples were also measured in a complementary method using high-energy carbon beams to evaluate the electron densities. The measured electron densities were compared with the theoretical values or the values measured in the complementary method. It was found that these values were in agreement in 0.9% on average. Effective atomic numbers were obtained as well from dual-energy x-ray CT. The tomographic image based on each of the electron densities and the effective atomic number presents a different feature of the material, and its contrast drastically differs from that in a conventional CT image.
BACKGROUND: The functions of the nasal mucosa are regulated by numerous endogenous and exogenous influences. The innervation patterns are important for the control of the physiological nasal functions. In addition to the classic neurotransmitters different neuropeptides might play a regulating and modulating role in the nasal mucosa. Both the significance and the localization of neuropeptide Y (NPY) have not been fully elucidated. PATIENTS AND METHODS: Tissue samples of human inferior turbinates from 42 patients were taken during nasal surgery and preserved in phosphate-buffered paraformaldehyde or glutaraldehyde. Serial sections were incubated with antibodies against NPY and the ABC method was applied. In order to identify immunoelectron microscopic reactions a streptavidin-gold-marker was used. The findings were photodocumented by using a light- and transmission-electron microscope. RESULTS: NPY-positive terminals were mainly located in the adventitia of arterial vessels. There were also NPY-immunoreactive arterioles near to the glands. Periglandular a lower density of immunoreactions could be observed. NPY-positive fibers could be detected in the subepithelial connective tissue and at the glandular ducts. Immunoelectron microscopy revealed NPY within periglandular axons. CONCLUSIONS: Immunohistochemical and immunoelectron microscopical methods allow a detailed identification of the sympathetic cotransmitter NPY in arterial vessels of nasal mucosa in man. These results indicate that NPY-containing nerve fibers innervate arteries as well as nasal glands. These findings suggest that NPY play a significant role as a neuromodulator in the control of both vasculature and glandular secretion. The localisation of NPY in periglandular and periductal nerves confirms the direct influence of glandular functions. NPY-agonists may be a beneficial additional treatment of rhinopathies to reduce nasal obstruction and mucus secretion.
MOSFET dosimeters are seeing increased use for various dosimetry applications. Previously available commercial MOSFET dosimeters demonstrate significant anisotropies in the response when irradiated from certain directions at diagnostic x-ray energies. The angular response of a more recently introduced MOSFET dosimeter that claims an isotropic response to incident radiation is characterized. Measurements of the Thomson-Nielsen model TN-502RDI dosimeter were made for rotations of 360 degrees in 15 degrees increments about both the axial and normal-to-axial axes. These measurements demonstrated that the model TN-502RDI dosimeter has a nearly isotropic response at diagnostic x-ray energies with variations of less than 3% deviation from the mean response for radiation incident from most directions. Only two specific orientations showed significant deviation from the overall isotropic response. These correspond to the exposure scenarios where radiation is incident directly along the axis where the wire leads attach to the MOSFET device and the distal tip, the 90 degrees and 270 degrees orientations for normal-to-axial rotations, respectively. The largest deviations from an isotropic response occur when the dosimeter is irradiated free-in-air. Irradiations performed at the center of a tissue equivalent cylinder resulted in smaller deviations in angular response. The improved angular response of the TN-502RDI allows greater freedom in placement and use of MOSFET dosimeters in diagnostic radiology applications.