scholarly journals The Estimation of Fœtal Maturity by a New Method of X-ray Cephalometry: Its Bearing on Clinical Midwifery

1935 ◽  
Vol 28 (5) ◽  
pp. 489-504 ◽  
Author(s):  
L. N. Reece
Keyword(s):  
New Method ◽  
X Rays ◽  
Short Axis ◽  
Simple Method ◽  
Circular Section ◽  
Foetal Head ◽  
X Ray ◽  
Special Apparatus

A plea is made for routine use of X-rays in antenatal work. A new method of cephalometry is described, depending on the fact that the fœtal head is a rough ovoid. It is shown that the shadows cast by ovoids may be oval or circular, but that always the diameter of the greatest circular section of an ovoid is represented in its shadow—by the diameter if the shadow be circular or by the short axis if oval. The results are applied to estimate the actual proportions of fœtal head and maternal pelvis, and also to estimate fœtal maturity. The accuracy of the method of cephalometry was tested in 100 cases of labour induced by rupture of membranes. A simple method of pelvimetry is described, and it is suggested that pelvimetry should be carried out in the early months and not later when the pelvis is obscured. No special apparatus is required and any cottage-hospital X-ray set will serve.

scholarly journals Limits on mass outflow from optical tidal disruption events

2021 ◽  
Vol 502 (3) ◽  
pp. 3385-3393
Author(s):  
Tatsuya Matsumoto ◽  
Tsvi Piran
Keyword(s):  
Energy Band ◽  
New Method ◽  
Hydrodynamic Modelling ◽  
X Rays ◽  
Will Emit ◽  
Tidal Disruption ◽  
X Ray ◽  
Mass Outflow ◽  
Current Sample ◽  
Stellar Masses

ABSTRACT The discovery of optical/UV (ultraviolet) tidal disruption events (TDEs) was surprising. The expectation was that, upon returning to the pericentre, the stellar-debris stream will form a compact disc that will emit soft X-rays. Indeed, the first TDEs were discovered in this energy band. A common explanation for the optical/UV events is that surrounding optically thick matter reprocesses the disc’s X-ray emission and emits it from a large photosphere. If accretion follows the super-Eddington mass infall rate, it would inevitably result in an energetic outflow, providing naturally the reprocessing matter. We describe here a new method to estimate, using the observed luminosity and temperature, the mass and energy of outflows from optical transients. When applying this method to a sample of supernovae, our estimates are consistent with a more detailed hydrodynamic modelling. For the current sample of a few dozen optical TDEs, the observed luminosity and temperature imply outflows that are significantly more massive than typical stellar masses, posing a problem to this common reprocessing picture.

scholarly journals Soft X-ray Lensless Imaging in Reflection Mode

Photonics ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 569
Author(s):  
Horia Popescu ◽  
Franck Fortuna ◽  
Renaud Delaunay ◽  
Nicolas Jaouen ◽  
Carlo Spezzani ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Coherent Scattering ◽  
New Method ◽  
X Rays ◽  
Reflection Mode ◽  
Lensless Imaging ◽  
X Ray ◽  
X Ray Imaging ◽  
Feasibility Test

We report on the development and implementation of methodologies dedicated to soft X-ray imaging by coherent scattering in reflection mode. Two complementary approaches are tested, based on Fourier transform holography and on ptychography. A new method for designing holographic masks has been developed. Our results represent a feasibility test and highlight the potential and limitations of imaging in reflection mode. Reflectivity is less efficient than transmission at soft X-ray wavelengths, hampering the acquisition of good quality images. Nonetheless, it has the potential to image a wider set of samples, notably those that are not transparent to soft X-rays. Although the images obtained so far are of modest quality, these results are extremely encouraging for continuing the development of coherent soft X-ray imaging in reflection mode.

scholarly journals K-Shell Fluorescence Yield of Thorium Present in its Compound

2009 ◽  
Vol 8 (2) ◽  
pp. 54-58
Author(s):  
L. D. Horakeri ◽  
S. G. Bubbly ◽  
S. B. Gudennavar
Keyword(s):  
Fluorescence Yield ◽  
Radioactive Source ◽  
X Rays ◽  
Geometrical Configuration ◽  
Simple Method ◽  
X Ray ◽  
Fluorescence Parameters ◽  
Good Agreement

A simple method, proposed by us earlier, - 2π geometrical configuration coupled with the thickness criterion - to measure the Kshell X-ray fluorescence parameters is extended to high Z material- Thorium. The fluorescent X-rays are generated by a weak Co-57 radioactive source and detected by employing a NaI (Tl) detector spectrometer. Measured value is compared with the best fitted value produced by Hubbell et al. and with the experimental value of Balakrishna et al. We found good agreement with each other, thus establishing the applicability of our simple method for measuring fluorescence yield of high Z element.

scholarly journals Simple method for detecting idiopathic interstitial pneumonias by measuring vertical lung length on chest X-ray

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Masato Karayama ◽  
Yoichiro Aoshima ◽  
Hideki Yasui ◽  
Hironao Hozumi ◽  
Yuzo Suzuki ◽  
...  
Keyword(s):  
Operating Characteristic ◽  
Characteristic Curve ◽  
Area Under The Curve ◽  
X Rays ◽  
Simple Method ◽  
X Ray ◽  
Idiopathic Interstitial Pneumonias ◽  
Chest X Ray ◽  
Costophrenic Angle ◽  
Tracheal Carina

AbstractDetection of idiopathic interstitial pneumonias (IIPs) on chest X-ray is difficult for non-specialist physicians, especially in patients with mild IIPs. The current study aimed to evaluate the usefulness of a simple method for detecting IIPs by measuring vertical lung length (VLL) in chest X-rays to quantify decreased lung volume. A total of 280 consecutive patients with IIPs were randomly allocated to exploratory and validation cohorts, and 140 controls were selected for each cohort by propensity score-matching. Upper (uVLL; from apex to tracheal carina), lower (lVLL; from carina to costophrenic angle), and total VLL (tVLL; from apex to costophrenic angle), and the l/uVLL ratio were measured on chest X-rays. Patients in the exploratory cohort had significantly decreased uVLL, lVLL, tVLL, and l/uVLL ratio compared with controls (all p < 0.001). Receiver operating characteristic curve analyses demonstrated that lVLL (area under the curve [AUC] 0.86, sensitivity 0.65, specificity 0.92), tVLL (AUC 0.83, sensitivity 0.75, specificity 0.80), and l/uVLL ratio (AUC 0.80, sensitivity 0.72, specificity 0.79) had high diagnostic accuracies for IIPs. These results were reproduced in the validation cohort. IIP patients thus have decreased VLLs, and measurements of VLL may thus aid the accurate detection of IIPs.

Using Voxel Count Measurements Based On X-Ray Attenuation Coefficient Principle to Estimate Organ Volume during CT Scan

2017 ◽  
pp. 653-659
Author(s):  
Issahaku Shirazu ◽  
Y. B Mensah ◽  
Cyril Schandorf ◽  
S. Y. Mensah
Keyword(s):  
Attenuation Coefficient ◽  
The Body ◽  
Linear Attenuation Coefficient ◽  
X Rays ◽  
Simple Method ◽  
Attenuation Coefficients ◽  
X Ray ◽  
Organ Volume ◽  
Count Method ◽  
Body Tissues

The study provided a simple method of using voxel count method to estimate organ volume together with x-ray attenuation coefficient principle. The aim is to discuss the role of x-ray attenuation coefficient in CT organ volume measurements using voxel count method. The method involve using the principle of linear attenuation coefficient which describes the fraction of a beam of x-rays or gamma rays that is absorbed or scattered per unit thickness of the absorber to enable tissue differentiation and hence the used of volume elements method, where the body is literally divided into 3-dimensional rectangular boxes with known size and thickness. This value basically accounts for the number of atoms within a specified distance of a material and the probability of a photon being scattered or absorbed from the nucleus or an electron of one of these atoms. A graph of linear attenuation coefficients versus radiation energy are used to separate between various body tissues. At a specific energy the difference in attenuation between two tissues is greatest at a specific radiographic contrast in an image. Hence, this variation enable a separation and subsequent measurements of varied tissues. Therefore, it is extremely useful to determine various linear attenuation coefficients of tissues to enable various variations to be determine for clinical application.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Chemical Species Identification in an SEM by Changes in Emitted X-Ray Energies

1974 ◽  
Vol 32 ◽  
pp. 570-571
Author(s):  
R. H. Duff
Keyword(s):  
Species Identification ◽  
Valence Electron ◽  
Chemical Species ◽  
X Rays ◽  
Chemical Bonds ◽  
Small Shift ◽  
X Ray ◽  
Electron Transitions ◽  
Peak Energy ◽  
Chemical Combination

A material irradiated with electrons emits x-rays having energies characteristic of the elements present. Chemical combination between elements results in a small shift of the peak energies of these characteristic x-rays because chemical bonds between different elements have different energies. The energy differences of the characteristic x-rays resulting from valence electron transitions can be used to identify the chemical species present and to obtain information about the chemical bond itself. Although these peak-energy shifts have been well known for a number of years, their use for chemical-species identification in small volumes of material was not realized until the development of the electron microprobe.

Influence of X-Ray Induced Fluorescence on Energy Dispersive X-Ray Analysis of Thin Foils

1977 ◽  
Vol 35 ◽  
pp. 328-329
Author(s):  
E. A. Kenik ◽  
J. Bentley
Keyword(s):  
Thin Foil ◽  
Electron Excitation ◽  
Simple Approach ◽  
Foil Thickness ◽  
X Rays ◽  
X Ray ◽  
Hole Spectrum ◽  
Illumination System ◽  
Thin Foils ◽  
Intensity Ratios

Cliff and Lorimer (1) have proposed a simple approach to thin foil x-ray analy sis based on the ratio of x-ray peak intensities. However, there are several experimental pitfalls which must be recognized in obtaining the desired x-ray intensities. Undesirable x-ray induced fluorescence of the specimen can result from various mechanisms and leads to x-ray intensities not characteristic of electron excitation and further results in incorrect intensity ratios.In measuring the x-ray intensity ratio for NiAl as a function of foil thickness, Zaluzec and Fraser (2) found the ratio was not constant for thicknesses where absorption could be neglected. They demonstrated that this effect originated from x-ray induced fluorescence by blocking the beam with lead foil. The primary x-rays arise in the illumination system and result in varying intensity ratios and a finite x-ray spectrum even when the specimen is not intercepting the electron beam, an ‘in-hole’ spectrum. We have developed a second technique for detecting x-ray induced fluorescence based on the magnitude of the ‘in-hole’ spectrum with different filament emission currents and condenser apertures.

X-ray micro tomography in the scanning electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 106-107 ◽  
Author(s):  
W. Brünger
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Target Surface ◽  
The Body ◽  
X Rays ◽  
Cross Sectional ◽  
X Ray ◽  
Micro Tomography ◽  
Scanning Electron

Reconstructive tomography is a new technique in diagnostic radiology for imaging cross-sectional planes of the human body /1/. A collimated beam of X-rays is scanned through a thin slice of the body and the transmitted intensity is recorded by a detector giving a linear shadow graph or projection (see fig. 1). Many of these projections at different angles are used to reconstruct the body-layer, usually with the aid of a computer. The picture element size of present tomographic scanners is approximately 1.1 mm2.Micro tomography can be realized using the very fine X-ray source generated by the focused electron beam of a scanning electron microscope (see fig. 2). The translation of the X-ray source is done by a line scan of the electron beam on a polished target surface /2/. Projections at different angles are produced by rotating the object.During the registration of a single scan the electron beam is deflected in one direction only, while both deflections are operating in the display tube.

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