Siemens Aktiengesellschaft

Sebastian Wolf

Markus Vester

Wolfgang Renz

Juergen Nistler

Dirk Diehl

Rene Gumbrecht

Juergen Leppert

Helmut Winkelmann

Thomas Hilderscheid

Manuel Kroiss

Wilhelm Hekele

Alexander Fege

Ignacio Garcia Francisco

Dirk Fleischmann

In a magnetic resonance apparatus having an RF radiating coil and gradient coils, and in a method for operating such a magnetic resonance apparatus, a pulse sequence, composed of multiple time steps, is specified for operating the gradient coils to time-dependently select regions of a selected slice of a selected volume of a subject. A non-linear equation system is then solved to obtain feed parameters for individual channels of the transmit coil for each time step, with specification of a desired target magnetization, and dependent on the pulse sequence specified for the gradient coils. The non-linear equation system is based on discrete values for time and space variable and, in addition to equations resulting from the Bloch equation, which are non-linear in their feed parameters, includes at least one additional equation that describes boundary conditions for the examination of the subject.

Magnetic resonance apparatus and method for determining a pulse sequence to feed an RF radiating coil

A control device for a magnetic resonance system activates the coils of a transmission array and a gradient magnet system of the magnetic resonance system by causing an excitation pulse to be supplied to each coil. A magnetization that exhibits a first actual inhomogeneity thereby is generated in an excitation volume of the magnetic resonance system. The control device determines the excitation pulse for each coil using a start pulse and a maximum allowable inhomogeneity. The respective start pulse has a total time duration. When the control device activates the coils of the transmission array and of the gradient magnet system corresponding to the start pulse, a magnetization that exhibits a second actual inhomogeneity that is smaller than the maximum permissible inhomogeneity is generated in the excitation volume. The control device determines an intermediate point of the start pulse so that the respective start pulse is divided into a first pulse part and a second pulse part that is complementary to the first pulse part. The first pulse part corresponds to a respective low-energy portion of the start pulse, the second pulse part with a high-energy portion of the respective start pulse. The control device temporally extends the second pulse part and correspondingly compresses the second pulse part in terms of amplitude. The temporally extended and amplitude-compressed pulse part is used as the excitation pulse. The control device determines the intermediate point such that the first inhomogeneity is still smaller than the maximum allowable inhomogeneity.

Control method for SAR-optimized activation of a coil array

A radiation detector is disclosed for the detection of ionizing radiation, preferably in a medical diagnosis and/or therapy system, having at least one detector element which is at least partially enclosed by an encapsulation compound. The encapsulation compound at least partially reflects light which is produced during the absorption of the ionizing radiation in the at least one detector element. Further, the detection of the radiation is carried out indirectly by detection of the generated light, wherein the encapsulation compound is made of a multicomponent mixture which converts compounds produced because of radiation, which generate color changes of the encapsulation compound, at least partially into colorless nonabsorbing compounds.

Radiation detector

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Adelsdorf, Germany

Sebastian Wolf