Infracranial radiographic comparison for human identification: A study of image quality and tissue shielding effects

1977 ◽

Vol 35 ◽

pp. 214-217

Author(s):

F. A. Heckman ◽

E. Redman ◽

J.E. Connolly

Keyword(s):

Image Analysis ◽

Image Quality ◽

Exposure Time ◽

Image Contrast ◽

Automated Image Analysis ◽

Practical Application ◽

Factors Affecting ◽

High Image Quality ◽

Qualitative Evidence ◽

Comprehensive Study

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.

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Observability of Very Thick Specimen by Using Transmission Scanning Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064189 ◽

1971 ◽

Vol 29 ◽

pp. 26-27

Author(s):

K. Shibatomi ◽

T. Yamanoto ◽

H. Koike

Keyword(s):

Electron Microscope ◽

Image Quality ◽

Scanning Electron Microscope ◽

Chromatic Aberration ◽

Image Contrast ◽

Objective Lens ◽

Thick Specimen ◽

Transmission Electron ◽

Scanning Electron

In the observation of a thick specimen by means of a transmission electron microscope, the intensity of electrons passing through the objective lens aperture is greatly reduced. So that the image is almost invisible. In addition to this fact, it have been reported that a chromatic aberration causes the deterioration of the image contrast rather than that of the resolution. The scanning electron microscope is, however, capable of electrically amplifying the signal of the decreasing intensity, and also free from a chromatic aberration so that the deterioration of the image contrast due to the aberration can be prevented. The electrical improvement of the image quality can be carried out by using the fascionating features of the SEM, that is, the amplification of a weak in-put signal forming the image and the descriminating action of the heigh level signal of the background. This paper reports some of the experimental results about the thickness dependence of the observability and quality of the image in the case of the transmission SEM.

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An Environmental Wet Cell For High Voltage Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100070539 ◽

1973 ◽

Vol 31 ◽

pp. 18-19

Author(s):

N.J. Tighe ◽

H.M. Flower ◽

P.R. Swann

Keyword(s):

Electron Microscopy ◽

High Temperature ◽

Image Quality ◽

Inelastic Scattering ◽

High Voltage ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

Environmental Cell ◽

Water Saturated ◽

High Temperature Gas

A differentially pumped environmental cell has been developed for use in the AEI EM7 million volt microscope. In the initial version the column of gas traversed by the beam was 5.5mm. This permited inclusion of a tilting hot stage in the cell for investigating high temperature gas-specimen reactions. In order to examine specimens in the wet state it was found that a pressure of approximately 400 torr of water saturated helium was needed around the specimen to prevent dehydration. Inelastic scattering by the water resulted in a sharp loss of image quality. Therefore a modified cell with an ‘airgap’ of only 1.5mm has been constructed. The shorter electron path through the gas permits examination of specimens at the necessary pressure of moist helium; the specimen can still be tilted about the side entry rod axis by ±7°C to obtain stereopairs.

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Image quality vs data obtainment in biological electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141950 ◽

1986 ◽

Vol 44 ◽

pp. 42-43

Author(s):

J. E. Johnson

Keyword(s):

Electron Microscopy ◽

Endoplasmic Reticulum ◽

Electron Beam ◽

Image Quality ◽

High Speed ◽

Early Period ◽

Early Years ◽

Fluorescent Screen ◽

Embedding Medium

In the early years of biological electron microscopy, scientists had their hands full attempting to describe the cellular microcosm that was suddenly before them on the fluorescent screen. Mitochondria, Golgi, endoplasmic reticulum, and other myriad organelles were being examined, micrographed, and documented in the literature. A major problem of that early period was the development of methods to cut sections thin enough to study under the electron beam. A microtome designed in 1943 moved the specimen toward a rotary “Cyclone” knife revolving at 12,500 RPM, or 1000 times as fast as an ordinary microtome. It was claimed that no embedding medium was necessary or that soft embedding media could be used. Collecting the sections thus cut sounded a little precarious: “The 0.1 micron sections cut with the high speed knife fly out at a tangent and are dispersed in the air. They may be collected... on... screens held near the knife“.

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The influence of confocal microscope design on imaging performance

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100146564 ◽

1993 ◽

Vol 51 ◽

pp. 144-145

Author(s):

C J R Sheppard

Keyword(s):

Image Quality ◽

Fluorescence Imaging ◽

Confocal Microscope ◽

Industrial Applications ◽

Three Dimensions ◽

Design Parameters ◽

Weak Signals ◽

Size And Shape ◽

Imaging Performance ◽

Fundamental Limitation

The confocal microscope is now widely used in both biomedical and industrial applications for imaging, in three dimensions, objects with appreciable depth. There are now a range of different microscopes on the market, which have adopted a variety of different designs. The aim of this paper is to explore the effects on imaging performance of design parameters including the method of scanning, the type of detector, and the size and shape of the confocal aperture.It is becoming apparent that there is no such thing as an ideal confocal microscope: all systems have limitations and the best compromise depends on what the microscope is used for and how it is used. The most important compromise at present is between image quality and speed of scanning, which is particularly apparent when imaging with very weak signals. If great speed is not of importance, then the fundamental limitation for fluorescence imaging is the detection of sufficient numbers of photons before the fluorochrome bleaches.

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Assessment of extracranial-intracranial bypass in Moyamoya disease using 3T time-of-flight MR angiography: Comparison with CT angiography

VASA ◽

10.1024/0301-1526/a000363 ◽

2014 ◽

Vol 43 (4) ◽

pp. 278-283 ◽

Cited By ~ 8

Author(s):

Qian Chen ◽

Rongfeng Qi ◽

Xiaoqing Cheng ◽

Changsheng Zhou ◽

Song Luo ◽

...

Keyword(s):

Image Quality ◽

Moyamoya Disease ◽

Mr Angiography ◽

Time Of Flight ◽

Consecutive Series ◽

Tof Mra ◽

Bypass Patency ◽

Significant Difference ◽

Contrast Technique ◽

Vessel Integrity

Background: To evaluate the value of time-of-flight MR angiography (TOF MRA) for the assessment of extracranial-intracranial (EC-IC) bypass in Moyamoya disease in comparison with computed tomography angiography (CTA). Patients and methods: A consecutive series of 23 patients with Moyamoya disease were analyzed retrospectively. Twenty three patients underwent 25 procedures of extracranial-intracranial bypass. Cranial CTA was performed within one week after the surgery to assess bypass patency. Then TOF MRA was scanned within 24 h after CTA on a 3T MRI system. Using 5-point scales (0 = poor to 4 = excellent), two radiologists rated the image quality and vessel integrity of bypass for three segments (extracranial, trepanation, intracranial). Results: Image quality was high in both CTA and TOF MRA (mean quality score 3.84 ± 0.37 and 3.8 ± 0.41), without statistical difference (p = 0.66). Mean scores of TOF MRA with respect to bypass visualization were higher than CTA in the intracranial segment (p = 0.026). No significant difference of bypass visualization regarding the extracranial and trepanation segments was found between TOF MRA and CTA (p = 0.66 and p = 0.34, respectively). For the trepanation segment, TOF MRA showed pseudo lesions in 2 of all 25 cases. Conclusions: 3T TOF MRA, a non-contrast technique not exposing the patients to radiation, proved to be at least equal to CTA for the assessment of EC-IC bypass, and even superior to CTA with respect to the intracranial segment. In addition, readers should be aware of a potential overestimation showing focal pseudo lesions of the bypass at the trepanation segment in TOF MRA.

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