Abstract: A method for operating an MR system with a gradient pulse amplifier unit that has an end stage connected to a gradient coil with switching elements is provided. The gradient pulse amplifier unit includes a modulator for actuating the switching elements, and lockout switches interconnected in signal paths from the modulator to the switching elements. The gradient pulse amplifier unit includes feeder circuit breakers interconnected in at least some signal paths from the modulator to the switching elements. The circuit breakers are connected in the associated signal paths downstream of the lockout switches. A gradstop unit configured to receive at least one shut-off signal and actuate the lockout switches and the feeder circuit breakers. When the gradstop unit receives a shut-off signal, the gradstop unit actuates the lockout switches to lock out and the feeder circuit breakers to output an actuation signal to the switching elements.

Abstract: A method for operating an MR system with a gradient power amplifier having at least one output stage that is connectable to a gradient coil, and having four switching elements connected to one another as an H-bridge includes, to operate the gradient coil, in alternation: switching the switching elements attached to a common first pole of a voltage supply to conductive and switching the switching elements attached to a common second pole of a voltage supply to blocking by inverting power drivers; and switching the switching elements attached to a common first pole of a voltage supply to blocking and switching the switching elements attached to a common second pole of a voltage supply to conductive by inverting power drivers. The switching elements attached to the first pole are switched by non-inverting power drivers, and the switching elements attached to the second pole are switched by inverting power drivers.

Abstract: A method for operating an MR system with a gradient pulse amplifier unit that has an end stage connected to a gradient coil with switching elements is provided. The gradient pulse amplifier unit includes a modulator for actuating the switching elements, and lockout switches interconnected in signal paths from the modulator to the switching elements. The gradient pulse amplifier unit includes feeder circuit breakers interconnected in at least some signal paths from the modulator to the switching elements. The circuit breakers are connected in the associated signal paths downstream of the lockout switches. A gradstop unit configured to receive at least one shut-off signal and actuate the lockout switches and the feeder circuit breakers. When the gradstop unit receives a shut-off signal, the gradstop unit actuates the lockout switches to lock out and the feeder circuit breakers to output an actuation signal to the switching elements.

Abstract: A method for operating an MR system with a gradient power amplifier having at least one output stage that is connectable to a gradient coil, and having four switching elements connected to one another as an H-bridge includes, to operate the gradient coil, in alternation: switching the switching elements attached to a common first pole of a voltage supply to conductive and switching the switching elements attached to a common second pole of a voltage supply to blocking by inverting power drivers; and switching the switching elements attached to a common first pole of a voltage supply to blocking and switching the switching elements attached to a common second pole of a voltage supply to conductive by inverting power drivers. The switching elements attached to the first pole are switched by non-inverting power drivers, and the switching elements attached to the second pole are switched by inverting power drivers.

Abstract: Methods and systems for controlling patient stimulating effects in MR imaging. The methods and systems include calculating a first effective stimulus duration independently for each pulse flank of an MRI sequence individually and calculating a second effective stimulus duration for which a respective history of a changing gradient field during the sequence is taken into account. Dependent on an evaluation of both the first and second effective stimulus durations a threshold value for an allowable rate of change in the magnetic gradient field is then calculated. The respective MRI sequence is then evaluated against the calculated threshold value to determine whether or not the respective MRI sequence is safe to apply.

Abstract: A method and system for determining a magnetic field map in a MR system based on position of a movable patient support of the MR system are provided, wherein a first resulting field map including position dependent information about a magnetic field distribution in a homogeneity volume including an examination volume of the MR system is provided when the movable patient support is located at a first position, wherein a stationary field map including information about a magnetic field distribution in the homogeneity volume is provided, which is independent of the position of the movable patient support, wherein a position dependent field map including information about a magnetic field distribution in the homogeneity volume mainly influenced by a position of the movable patient support is determined using the stationary field map and the first resulting field map, and wherein a second resulting field map in the homogeneity volume is determined when the movable patient support is located at a second position di

Abstract: Methods and systems for controlling patient stimulating effects in MR imaging. The methods and systems include calculating a first effective stimulus duration independently for each pulse flank of an MRI sequence individually and calculating a second effective stimulus duration for which a respective history of a changing gradient field during the sequence is taken into account. Dependent on an evaluation of both the first and second effective stimulus durations a threshold value for an allowable rate of change in the magnetic gradient field is then calculated. The respective MRI sequence is then evaluated against the calculated threshold value to determine whether or not the respective MRI sequence is safe to apply.

Abstract: A method for recording a B0 map of a main magnetic field of a magnetic resonance device in an imaging volume of which an object to be recorded is arranged includes scanning a recording region to be covered by the B0 map by the magnetic resonance device. The recording region is scanned by a map recording sequence slice-by-slice in successive slices in a slice selection direction extending in a phase encoding direction and a readout direction, or three-dimensionally using two phase encoding directions and one readout direction in order to ascertain the B0 map. In a preliminary scan, the magnetic resonance device ascertains extension information describing the extension of the object using a scout sequence, which is used to define the recording region in sequence parameters of the map recording sequence and/or to adjust at least one sequence parameter of the map recording sequence.

Abstract: Eddy current induced magnetic fields (MF) are compensated in a magnetic resonance imaging system. An MR-sequence (M) includes a number of gradients. A dataset includes values of an amplitude and a time constant of eddy current fields of a number of gradients on at least one gradient axis. A number of points in time within the time period of the MR-sequence are defined. A number of constant currents are calculated for a number of coils of the magnetic resonance imaging system based on the dataset. The number of constant currents is designed to compensate at least at the one defined point in time (PT1, PT2). The calculated number of constant currents are applied on the related coils prior or during the application of the MR-sequence or a section of the MR-sequence.

Abstract: A method and system for determining a magnetic field map in a MR system based on position of a movable patient support of the MR system are provided, wherein a first resulting field map including position dependent information about a magnetic field distribution in a homogeneity volume including an examination volume of the MR system is provided when the movable patient support is located at a first position, wherein a stationary field map including information about a magnetic field distribution in the homogeneity volume is provided, which is independent of the position of the movable patient support, wherein a position dependent field map including information about a magnetic field distribution in the homogeneity volume mainly influenced by a position of the movable patient support is determined using the stationary field map and the first resulting field map, and wherein a second resulting field map in the homogeneity volume is determined when the movable patient support is located at a second position di

Abstract: A method for recording a B0 map of a main magnetic field of a magnetic resonance device in an imaging volume of which an object to be recorded is arranged includes scanning a recording region to be covered by the B0 map by the magnetic resonance device. The recording region is scanned by a map recording sequence slice-by-slice in successive slices in a slice selection direction extending in a phase encoding direction and a readout direction, or three-dimensionally using two phase encoding directions and one readout direction in order to ascertain the B0 map. In a preliminary scan, the magnetic resonance device ascertains extension information describing the extension of the object using a scout sequence, which is used to define the recording region in sequence parameters of the map recording sequence and/or to adjust at least one sequence parameter of the map recording sequence.

Abstract: A method for adapting activation parameters used to generate a pulse sequence when activating a magnetic resonance system is provided. The method includes determining stimulation values for the pulse sequence based on predefined activation parameters. The stimulation values represent a stimulation exposure of a patient. Test regions that exhibit stimulation maxima are identified in the pulse sequence, and the identified test regions are tested with respect to compliance with a predefined stimulation limit value.

Abstract: A method is disclosed for detecting x-rays using an x-ray detector which includes a direct-conversion semiconductor detector element. Additional radiation is supplied to the semiconductor detector element using a radiation source, and the supply of the additional radiation is controlled and/or regulated on the basis of a specified target value. In at least one embodiment, the target value can be specified in a variable manner over time as a sequence of target values. An x-ray detector system is further disclosed, with which the method can be carried out.

Abstract: A direct-converting x-ray radiation detector is disclosed for detecting x-ray radiation, in particular for use in a CT system. In an embodiment, the detector includes a semiconductor material used for detecting the x-ray radiation; at least one collimator; and at least one radiation source, to irradiate the semiconductor material with additional radiation. In at least one embodiment, the at least one collimator includes at least one reflection layer on a side facing the semiconductor material, on which the additional radiation is reflected to the semiconductor material. In another embodiment, a CT system including the direct-converting x-ray radiation detector, and a method for detecting incident x-ray radiation via a direct-converting x-ray radiation detector, in particular for use in a CT system, are disclosed.

Abstract: A direct-converting x-ray radiation detector is disclosed for detecting x-ray radiation, at least including a semiconductor used to detect x-ray radiation and at least one electrode attached to the semiconductor. In an embodiment, the semiconductor and the at least one electrode are electrically conductively connected and the at least one electrode is designed to be transparent and electrically conductive. A CT system is further disclosed, at least including the direct-converting x-ray radiation detector.

Abstract: An X-ray detector with photon-counting directly converting detector elements and a method for the temperature stabilization of at least one detector element of an X-ray detector of a CT system are disclosed, wherein the detector elements use a sensor material which converts incident photons of radiation directly into free-moving charge in the sensor material and wherein with the aid of a circuit arrangement (e.g. an ASIC), the number of incident photons in relation to predefined energy ranges (e.g., to imaging) is determined, wherein the total electrical power of at least one detector element is kept constant regardless of the incident intensity of radiation.

Abstract: In order to enable efficient calculation of shim settings for a magnetic resonance imaging system, a method for magnetic resonance imaging of an object under investigation using a magnetic resonance device is provided. The method includes acquiring first magnetic resonance image data of the object under investigation using the magnetic resonance device. The method also includes segmenting the first magnetic resonance image data into at least two material classes, calculating a B0 map based on the segmented first magnetic resonance image data and based on susceptibility values of the at least two material classes, and calculating shim settings based on the calculated B0 map. The method also includes acquiring second magnetic resonance image data of the object under investigation using the magnetic resonance device. The acquisition of the second magnetic resonance image data is undertaken using the calculated shim settings.

Abstract: A method and a detector system are disclosed for the photon-counting detection of x-ray radiation with direct conversion detectors. In at least one embodiment of the method, as a function of the existing radiation energy, current and/or voltage pulses which are largely proportional thereto are generated, and the generated current and voltage pulses are counted in the detector when a predetermined current and/or voltage source is exceeded, whereby a threshold is used as a predetermined current and/or voltage threshold, which corresponds to a detection of a photon with an energy which is less than the k-edge of the detector material used.

Abstract: A direct-converting x-ray radiation detector is disclosed for detecting x-ray radiation, at least including a semiconductor used to detect x-ray radiation and at least one electrode attached to the semiconductor. In an embodiment, the semiconductor and the at least one electrode are electrically conductively connected and the at least one electrode is designed to be transparent and electrically conductive. A CT system is further disclosed, at least including the direct-converting x-ray radiation detector.

Abstract: An x-ray detector for a medical imaging device includes an anti-scatter grid, a measuring layer including a regular arrangement of measuring cells, and an evaluation unit. The anti-scatter grid covers the measuring layer and is aligned toward a specific focal point. The evaluation unit is configured to determine a focal position of an x-ray source relative to the focal point based on a local intensity difference of x-rays striking the measuring layer.