CT scanner

In this paper a new design for a high-energy 3D-CT scanner equipped with a linear accelerator as radiation source and an area high-energy x-ray detector is presented. This system is the extension of a 2D system which is installed at present time [3,4]. 

Various computed tomography CT- scanners for industrial applications have been designed and constructed) They use as radiation sources X-ray tubes or gamma emitting radioisotopes and as detectors NaI(Tl)-scintillators for gamma rays and image intensifiers for X-rays. 

The CT-scanners have been employed to various industrial samples such as concrete, asphalt, wood, ceramics and so on. 

Scintillators are also used in the detectors of CT scanners. Here an electronic detector, the photomultiplier tube, is used to produce an electrical signal from the visible and ultraviolet light photons. These imaging systems typically need fast scintillators with a high efficiency. 

A gas ionization detector consists of a tube filled with a high pressure gas and two electrodes. A tube filled with 2 MPa (20 atm) of xenon is common. The gas in the tube ionizes when x-rays pass through the tube causing a current to flow between a high voltage potential placed across the electrodes. This concept is similar to that used in a Geiger tube detector. Gas ionization detectors are utilized in some CT scanners. 

CT scanners are now nearly ubiquitous in or near the emergency departments of most North American hospitals. With multislice scanners, a noncontrast CT (NCCT) examination of the brain can be performed in well under 1 minute, with the newest scanners able to scan the head in 10 seconds or less. In most centers, the first (and sometimes only) imaging study undertaken for patients with suspected acute stroke is NCCT. 

The patient has been transferred from the CT scanner to the surgical intensive care unit for mechanical ventilation, blood pressure support, and surgical evaluation. A diagnosis of acute pancreatitis with pancreatic necrosis is made. 

Instrumentation for revealing the presence of bulk quantities of concealed drugs will differ from those developed to find evidence of minute quantities on surfaces. Bulk detection is concerned with amounts ranging from grams to kilograms [4], Bulk detection is done by manual inspection, X-ray, CT scans, and acoustic inspection. X-ray or CT scanners used as bulk detectors have sensitivity of 2-10 g, and suspect items are subsequently confirmed by chemical analysis. Hand-held acoustic inspection instruments such as the Acoustic Inspection Device (AID) and the Ultrasonic Pulse Echo (UPE) developed by Pacific Northwest National Laboratories/Battelle, can be used for analysis of cargo liquids in sealed containers of various sizes within seconds [5]. The acoustical velocity and attenuation of multiple echoes returned to the instrument is evaluated by software which compares the data to the shipping manifest. 

Barley, S. R. 1986. Technology as an occasion for structuring evidence from observations of CT scanners and the social order of radiology departments. Administrative Science Quarterly, 31 78-108. 

Other CT scanners do not use a first-stage screener, but instead they continuously generate contiguous slice images of the bag as it moves at a constant speed through the system on the conveyor. The system s software stacks these slices, one next to the other, to form the 3D density image. The software then searches the entire 3D image for threat objects. 

As depicted, the luggage moves from left to right after being placed on the tilted entrance conveyor, which then transitions to a horizontal motion for scanning. The larger structure in the center is the CT scanner section. Next comes the exit conveyor that transitions downward for ease in retrieving bags. Conveyors in the entrance tunnel, in the scanner section, and in the exit tunnel all run at the same speed. The two conveyor tunnels at either end each contain several sets of leaded... 

The abihty of X-ray CT scanners to capture information from the third dimension and to measure material properties directly gives them the abihty to markedly surpass conventional 2D X-ray systems in automatically discovering contraband and in making it visible to human operators. 

In 1998, the first PET/CT scanner, combining functional information with morphological information, was introduced by Townsend and co-workers [3], Combined PET/CT devices offer an efficient tool for whole-body staging and restaging functional assessment within one imaging modality. PET/CT scanners allow a merging of complementary information from CT and PET, leading to a more accurate anatomic localization. Furthermore, a more precise assessment of tumor volume is possible in comparison to PET. 

Micro-CT scanner—Several major manufacturers provide various models of scanners including Scanco, Xradia, Skyscan, General Electric, and Siemens. 

Final image acquisition—Once the scan parameters have been determined, a scout scan performed, and scan times deemed satisfactory, the next step is to run the micro-CT scanner for the final image acquisition. 

In type 1, process verification is required because of subsequent functional specifications for all products. Surgical equipment, such as scissors and tweezers, contact lenses, and eyeglasses are categorized type la. Diagnostic equipment, such as CT scanners, and treatment equipment, such as infusion pumps for the introduction of solution types of medicine and surgical aid solutions are categorized as type lb. In b, instructions for assembly at the user s site should be... 

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