U.S. Philips Corporation

Rudolf Kemner

Hilco T Kalmijn

Johannes J Stouten

Pieter Zuidhof

Herfried Karl Wieczorek

Ulrich Schiebel

Andreas Brauers

Edwin A Montie

Teunis R Van Heelsbergen

Wilhelmus R Mens

Frans Wessel Zonneveld

Petrus W Linders

Petrus N Vis

Eddy B Boskamp

Lambertus G Fokkink

Dirk Sinnema

Alfred Ketting

Rudy R Cramer

Hilbrand J Smit

Johanna A Sondag-Huet-Horst

Andre R De Wit

Frans J Berkers

Adriaan J Hoeven

Joost Egbert Marquerinck

Bernardus G Kuilman

Gerardus L Reuvers

An x-ray examination apparatus comprises an x-ray detector with a sensor matrix for deriving an image signal from an x-ray image. The x-ray detector is provided with a scatter grid having a regular pattern of x-ray attenuating partitions. The spatial resolution of the sensor matrix is such that the size of the smallest detectable detail in the x-ray image is larger than the distance between adjacent partitions. In particular the x-ray detector comprises an x-ray sensitive photoconductor layer for converting x-rays into electric charges, separate sensor elements include respective collecting electrodes and a semiconductor cladding layer being disposed between the photoconductor layer and the collecting electrodes. The semiconductor cladding layer has a substantial lateral electric conductivity. For example, the semiconductor cladding layer is a chlorine doped selenium layer, or a selenium, sulphur or telluride doped lead-oxide layer.

X-ray apparatus with sensor matrix

A phosphor screen in a display device is scanned by separate electron beams in order to generate images of different frequency content in one color in substantially the same part of the phosphor screen. The different images can be perceived as a composite image for some time. The individual electron beams can be modulated by means of a cathode modulator on the basis of a high frequency and a low frequency component of an electronic image signal or on the basis of an image component and a text component of an electronic image signal. The modulations of the individual electron beams may be slightly delayed relative to one another in order to avoid overloading of the phosphor material.

CRT display device comprising a filter in the cathode modulator

An X-ray apparatus is provided with a filter (12) for limiting the dynamic range of an X-ray image formed on an X-ray detector (4) by exposure of an object (3), for example a patient to be examined, to X-rays (2). The filter (12) has filter elements (13) including one or more capillary tubes (13), one end of which communicates with a reservoir with an X-ray absorbing liquid. The adhesion of the X-ray absorbing liquid to the inner side of the capillary tubes can be adjusted by means of an electric voltage applied to an electrically conductive layer provided on the inner side of the capillary tubes (13). The degree of filling of the capillary tubes (13) with the X-ray absorbing liquid is adjusted by way of the electric voltage value. The X-ray absorption profile is adjusted within a very short period of time, for example within one second, by adjustment of the electric voltages applied to the capillary tubes (13).

X-ray apparatus comprising a filter

It is known that perturbations caused by scattered-radiation in an x-ray image can be partially avoided by employing a scattered-radiation grid. A device for further improvement of an x-ray image, in that real-time correction of scattered-radiation effects is achieved, is provided according to the invention. Behind x-ray absorbing parts of the scattered-radiation grid only scattered-radiation appears, whereas both scattered-radiation and primary radiation appear behind transparent channels of the scattered-radiation grid. The scattered-radiation grid gives rise to a high-frequency intensity modulation in the x-ray image. From the high-frequency component of the corresponding video signal produced by the x-ray detector, selection signals are generated by a double pulse generator for distinguishing signal amplitudes of the video signal, corresponding to intensities behind absorbing parts and transparent parts, respectively, of the scattered-radiation grid. The selection signals are supplied to a synchronous detector to split the video signal from the x-ray detector into separated video signals corresponding to scattered-radiation and primary radiation and to scattered-radiation only, respectively. A video signal corresponding to a corrected image is obtained by subtraction of the separated video signals.

X-ray examination apparatus having means for correcting

Accumulation of charge between neighboring image lines can be prevented in a television pick-up tube in which an image pick-up face is scanned along image lines by an electron beam when a comparatively small periodic deflection is imposed on the electron beam in a direction perpendicular to the image lines. To achieve this, a magnetic deflection element in the form of a saddle-shaped coil is disposed between the vertical deflection element of the television pick-up tube and the envelope of the electron gun.

Television pick-up tube and deflection system for use in such a

The circuit has an input terminal (1) for supplying a picture signal (CS) formed line and field-sequentially with line and field or frame periods (TV) and an output terminal (2) for supplying a processed picture signal (CS') to be applied to a picture display device (5) comprising a picture display tube operating by way of electron beam scanning (e) of a display screen (8). In the circuit the input terminal (1) is coupled to a filter circuit (10) which has a first output (11) and a second output (12) for supplying a low-frequency (CS.sub.L) or high-frequency (CS.sub.H) picture signal component, respectively. The first output (11) is coupled via an amplifier circuit (16) to a first input (21) of a time-division multiplex circuit (20) having a second input (22) to which the first output (11) and the second output (12) of the filter circuit (10) are coupled each via an amplifier circuit (17, 18) and an adder circuit (19). The time-division multiplex circuit (20) has a switching input (23) which is coupled to an output (29) of a switching signal generator (28) for supplying a periodical switching signal (VS) of the double field or frame period (2TV). An output (24) of the time-division multiplex circuit (20) is coupled to the output terminal (2) of the picture signal processing circuit. The resultant spatial time-division multiplex display yields the improved high-frequency picture resolution.

Picture signal processing circuit for improving high-frequency picture

For measurements with increased accuracy in a nuclear magnetic resonance apparatus, the detection device is equipped with one or more surface coils which act as measuring coils. To avoid mutual interference between a radio-frequency transmitting coil and the measuring coil, the measuring coil is provided with a decoupling circuit. The surface coil and the decoupling circuit form a part of a tuned circuit which is tuned to a significantly higher natural frequency during activation of the transmitting coil. On the other hand, the transmitting coil is shorted during detection with the surface coil by a low resistance shorting circuit, thereby avoiding interference with the radio-frequency transmission signals.

Nuclear magnetic resonance apparatus with surface coil detection

As a result of the use of a slow phosphor in the exit screen of an X-ray image intensifier tube, a number of image fields can be picked up by means of the comparatively fast television camera during the afterglow of the phosphor. This enables quantum noise integration and, when use is made of a CCD camera upon display, a resolution can be achieved upon display which corresponds to the resolution of a conventional pick-up tube. Moreover, in accordance with the invention it is no longer necessary to use a controllable diaphragm and a complex interface for the asynchronous pick-up and reading of the image information.

X-ray imaging system

A quadrature mode rf coil system in a magnetic resonance apparatus includes a pair of orthogonal rf coils which, for excitation and/or detection are coupled to an rf source or receiver by an electronic switching circuit built up from inductances and capacities. The switching circuit includes preferably frequency adjustable 90.degree. first delay lines feeding each coil which transforms the 50.OMEGA. coil impedance of each coil to 100.OMEGA. so that the parallel combination of transformed impedances is 50.OMEGA.. A second 90.degree. delay line is cascaded with the first delay line feeding one of the coils to establish a 90.degree. phase difference between the coils.

Magnetic resonance apparatus having a quadrature RF coil system

Disclosed is a magnetic resonance imaging apparatus, with an r.f. coil which is designed on the basis of the sinusoidal current distribution across a circular-cylindrical surface about a central coil axis and which is, subject to a generally applicable looping-through condition z.sub.1 =-K z.sub.2, when K is a positive constant which depends on the number of bars and geometrical deviations, z.sub.1 is the impedance of the bar conductors, and z.sub.2 is the impedance of ring conductor elements between each two pair of bar conductors. The coil based on the above condition is particularly adapted to parasitic capacitances of the bar conductors and to the general shape of objects to be examined.

Magnetic resonance imaging apparatus including a bird-cage r.f. coil

In an apparatus for performing magnetic resonance measurements by means of an orthogonal system of excitation detection coils there is provided a switching circuit for powering and reading the coil system which includes a 1/4 .lambda. coaxial conductor as a connection between the two coil assemblies and a 1/4 .lambda. coaxial conductor with a 90.degree. phase delay as a connection between the first 1/4 .lambda. conductor and the second coil assembly and a detection device. By suitable tuning of the relevant circuit components and the coils, preferably based on 50 Ohms, a simple switching circuit with appropriate matching and phase correction is thus achieved. Specifically, the r.f. power source can be connected to the circuit via an n .lambda. conductor. In the open condition during detection, the n .lambda. conductor represents an infinite impedance for the switching circuit.

Magnetic resonance imaging apparatus including two orthogonal r.f. coils

For increasing the sensitivity of an MR apparatus when measuring comparatively high frequencies, the radio frequency excitation measurement coil (10, 30) is divided into two individual symmetrically drivable and readable coil halves (32, 34), respectively. The mutual connection of central connections of the coil halves can be realized by means of a balun (54) but for this purpose any other symmetrical form of coupling, for example using a strip-line transformer (70) or suitably dimensioned coaxial cables (60, 62) may alternatively be used.

MR-apparatus having a transmission-measuring coil for high frequencies

In a nuclear magnetic resonance apparatus, a loudspeaker element free of magnetic material acts as an acoustic reproduction element. The loudspeaker element is arranged in the magnet space so that the main field of the magnet acts to generate a Lorentz driving force for the element. Together with a microphone function or an additional microphone (50) and an external loudspeaker.microphone system, a two-way acoustic communication system can thus be formed. Such a loudspeaker element free from magnetic material does not produce field disturbances in the magnet.

Nuclear magnetic resonance apparatus having a communication system

The transmitter/measurement coil of a nuclear magnetic resonance tomography apparatus for medical diagnosis in which comparatively high Larmor frequencies are used, is divided into a number of parallel-connected subcoils. The self resonance frequency of the coil can thus be made substantially higher than the Larmor frequency, with the result that the coil will have a suitably improved quality factor at higher frequencies, and measurements can be performed with an acceptable signal-to-noise ratio.

Nuclear magnetic resonance tomography apparatus

A flare or scattered light compensation circuit for television, wherein a controllable signal difference amplifier is present to a first input of which a picture signal, affected by flare or scattered light, is applied, a compensation signal obtained by signal integration being applied to a second input. The gain factor of the amplifier is controlled substantially proportional to the quotient of the peak-peak value of the picture signal and of the difference value of the said peak-peak value and the value of the compensation signal.

Growing community of inventors

Eindhoven, Netherlands

Rudolf Kemner