A radiological imaging apparatus of the present invention comprises an image pickup device and a medical examinee holding device that is provided with a bed. The image pickup device includes a large number of radiation detectors and radiation detector support plates. A large number of radiation detectors are mounted around the circumference of a through-hole and arranged in the axial direction of the through-hole. The radiation detectors are arranged in three layers formed radially with respect to the center of the through-hole and mounted on the lateral surfaces of the radiation detector support plates. Since the radiation detectors are not only arranged in the axial direction and circumferential direction of the through-hole but also arrayed in the radial direction, it is possible to obtain accurate information about a γ-ray arrival position in the radial direction of the through-hole (the positional information about a radiation detector from which a γ-ray image pickup signal is output). The use of accurate information about γ-ray arrival increases the tomogram accuracy. As a result, the present invention enhances the tomogram accuracy, that is, the PET examination accuracy.

Radiological imaging apparatus

Portable x-ray devices and methods for using such devices are described. The devices have an x-ray tube powered by an integrated power system. The x-ray tube is shielded with a low-density insulating material containing a high-Z substance. The devices can also have an integrated display component. With these components, the size and weight of the x-ray devices can be reduced and the portability of the devices enhanced. The x-ray devices also have an x-ray detecting means that is not structurally attached to the device and therefore is free standing. Consequently, the x-ray devices can also be used as a digital x-ray camera. The portable x-ray devices are especially useful for applications where portability is an important feature such as in field work, remote operations, and mobile operations such as nursing homes, home healthcare, or teaching classrooms. This portability feature can be particularly useful in multi-suite medical and dental offices where a single x-ray device can be used as a digital x­ray camera in multiple offices instead of requiring a separate device in every office.

Digital x-ray camera

A miniature x-ray source capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature x-ray source comprises a compact vacuum tube assembly containing a cathode (18), an anode (22), a high voltage feedthru (19) for delivering high voltage to the anode, a getter (26) for maintaining high vacuum, a connection for an initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feethru. At least a portion of the vacuum tube wall is highly x-ray transparent and made, for example, from boron nitride. The compact size and potential for remote operation allows the x-ray source, for example, to be placed adjacent to a material sample undergoing analysis or in proximity to the region to be treated for medical applications.

Miniature x-ray source

Systems and methods for generating a high voltage pulse. A series of voltage cells are connected such that charging capacitors can be charged in parallel and discharged in series. Each cell includes a main switch and a return switch. When the main switches are turned on, the capacitors in the cells are in series and discharge. When the main switches are turned off and the return switches are turned on, the capacitors charge in parallel. One or more of the cells can be inactive without preventing a pulse from being generated. The amplitude, duration, rise time, and fall time can be controlled with the voltage cells. Each voltage cell also includes a balance network to match the stray capacitance seen by each voltage cell.

High voltage pulsed power supply using solid state switches

The present invention is directed to a method and apparatus of multi-energy data acquisition. An imaging system is also provided and includes a number of HF electromagnetic energy filters. The filters include at least a first and a second filter wherein the first filter is positioned in a path of HF electromagnetic energy when an HF electromagnetic energy source is energized to a first voltage and the second filter is positioned in the path of HF electromagnetic energy when the HF electromagnetic energy source is energized to a second voltage.

Method and apparatus of multi-energy imaging

A portable X-ray unit, of a relatively light-weight, occoping a volume of less then one-half a cubic foot containing an x-ray head assembly, a unique Marx generator, a plurality of spark-gap switches and control electronics is disclosed. The Marx generator allows for the development of a relatively high voltage in excess of 100 kV, yet allows for the discharge thereof within the nanosecond range. The Marx generator is enclosed by an acrylic insulator that cooperates with an aluminum enclosure, which functions as a return current path for the capacitors in the Marx generator and also as a shield against the escape of electromagnetic radiation from the pulsed x-ray unit. The Marx generator and spark-gap switches are confined within the pressurized chamber that may contain nitrogen gas to reduce the separation of the gap in the spark-gap switches.

Mobile X-ray unit

A dual-energy x-ray system is provided which is useful in densitometry and other applications. A dual energy x-ray source, formed field emission x-ray tube driven by a Marx generator, produces a single x-ray pulse of a very short duration (e.g., 10 to 200 nanoseconds). The pulse provides x-ray energy of a first, high value early in the pulse and x-ray energy of a second, lower value later in the pulse so as to provide a dual energy level x-ray distribution comprising hard and soft x-rays. A detector system having dual x-ray energy discrimination properties, formed by soft and hard x-ray detectors and an inter-detector, receives the x-ray pulse and discriminates between the dual x-ray energy levels of the pulse.

Dual energy x-ray densitometry apparatus and method using single x-ray pulse

Properly designed augmented railguns (ARGs) can operate at significantly lower currents and higher efficiency than conventional non-ARGs. This paper analyzes the performance of a two-turn and a three-turn ARG showing the design parameters that are needed to achieve low-current high-efficiency operation. The ARG of this paper has a 40-mm square bore and is 820 mm long. Typical operating currents are from 150 to 300 kA with pulsewidths of approximately 6 to 8 ms. Projectile mass is typically in the range of 130 to 400 g. Projectile velocity is variable from 50 to 250 m/s. Experimental performance is compared with the theoretical predictions of the recently developed electromagnetic launcher (EML) equation. There is a good agreement between measured efficiency and theoretical predictions providing further confirmation of the EML equation. Deviations between measured efficiency and theoretical predictions are attributed to a poor sliding contact. The data also provide further evidence of the recently reported velocity-skin-effect in the contact.

Design of Low-Current High-Efficiency Augmented Railguns

The Naval Research Laboratory has developed an automatic electromagnetic launcher system for countermeasure deployment. The launcher operates at 1 Hz and can fire bursts of one to six 44-mm2 projectiles. The launcher is controlled from a computer that permits selection of the bank charging voltage and the number of shots. The present experimental setup consists of a railgun, an autoloader, and a rapid charger with computer control.

Automatic Multishot Operation of an Electromagnetic Launcher

A solid lubricating interfacial compound (SLIC) has been used to condition the rails and armature of the NRL decoy launcher, a low-speed (100-140 m/s) railgun. The study tested the hypothesis that a very thin film would protect the sliding electrical contacts against damage by friction, wear, and arcing. The film, obtained by rubbing the rail and armature staples with a PTFE-based composite, dramatically improved launch reliability, increased projectile speed, and reduced armature damage and armature/rail arcing. High-speed (68 kfps) videos taken down the bore showed that the SLIC treatment could suppress light emissions from start of launch until the muzzle flash. The treatment also reduced or completely suppressed the spikes in the muzzle-voltage traces. Optical microscopy identified the damage mechanisms responsible for both rail and armature wear. The SLIC treatment reduced or eliminated arc damage in the breech, attachment of Cu shards to the rail, and both melting and abrasive wear of the staples. The effect of the rubbed film on wear behavior is discussed.

Craig N. Boyer

Papers

Mobile X-ray unit

Dual energy x-ray densitometry apparatus and method using single x-ray pulse

Design of Low-Current High-Efficiency Augmented Railguns

Automatic Multishot Operation of an Electromagnetic Launcher

Wear Behavior of Lubricant-Conditioned Copper Rails and Armatures in a Railgun