SYNCHRONIZATION OF CLOCKS IN AUTONOMOUS COMPONENTS OF AN MR SYSTEM AND SYNCHRONOUS EXECUTION OF COMMANDS IN THOSE COMPONENTS

• US 20110040997A1
• Filed: 08/04/2010
• Published: 02/17/2011
• Est. Priority Date: 08/11/2009
• Status: Active Grant

• Current Assignee: Siemens Healthineers AG (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Pirkl, Georg, Werner, Roland, Demharter, Nikolaus, Baumgartl, Rudi
• Granted Patent: US 8,402,300 B2
• Time in Patent Office: Days
• US Class Current: 713/401
• CPC Class Codes: G01R 33/3607 RF waveform generators, e.g. frequency generators, amplitude-, frequency- or phase modulators or shifters, pulse programmers, digital to analog converters for the RF signal, means for filtering or attenuating of the RF signal
• CPC Class Codes: G01R 33/3621 NMR receivers or demodulators, e.g. preamplifiers, means for frequency modulation of the MR signal using a digital down converter, means for analog to digital conversion [ADC] or for filtering or processing of the MR signal such as bandpass filtering, resampling, decimation or interpolation
• CPC Class Codes: G01R 33/543 Control of the operation of the MR system, e.g. setting of acquisition parameters prior to or during MR data acquisition, dynamic shimming, use of one or more scout images for scan plane prescription G01R33/546 takes precedence

Abstract

In a device and a method to execute commands in components of an imaging system, in particular of a magnetic resonance tomography system, local clocks in the components are temporally synchronized, commands, including a respective command execution time specification which respectively specifies at which point in time a command should be executed, are sent to the components, the commands are received by the components, commands and command execution time specifications that are received by components are stored in these components, and a stored command is respectively executed when a time indicated by the local clock coincides with the stored command execution time specification regarding the command.

Claims

1. A method for executing commands in components of an imaging system, each of said components comprising a local clock, said method comprising the steps of:

temporally synchronizing the respective local clocks of said components in said imaging system;

transmitting commands to the respective components and including in the respective commands a command execution time specification that specifies a point in time at which the command should be executed that includes the respective command execution time specification;

receiving the respective commands at the respective components and storing the respective received commands at the respective components, as stored commands; and

at each component, automatically retrieving and executing a stored command when a point in time at the local clock at that component coincides with the command execution time specification of the stored command.

2. A method as claimed in claim 1 comprising selecting said components from the group consisting of transmitters in said imaging system and receivers in said imaging system.

3. A method as claimed in claim 1 wherein said commands have a time resolution associated therewith, and comprising providing the respective local clocks with a local clock time resolution sufficient to execute the respective commands according to the time resolution of the commands.

4. A method as claimed in claim 1 comprising temporally synchronizing said local clocks with a reproducible phase that causes all of the local clocks to indicate an identical clock time, by synchronizing said local clocks with each other or by synchronizing said local clocks with a reference clock.

5. A method as claimed in claim 1 comprising temporally synchronizing the respective local clocks by placing the respective local clocks in communication with a common system clock.

6. A method as claimed in claim 1 comprising temporally synchronizing the respective local clocks by providing a transmission clock in a data stream transmitted to the respective components.

7. A method as claimed in claim 1 comprising transmitting said commands, including said command execution time specification, from a synchronization master to the respective local clocks, the respective transmissions from the synchronization master to the respective local clocks each having a signal delay associated therewith, and automatically taking said signal delay into account when temporally synchronizing the respective local clocks.

8. A method as claimed in claim 1 comprising transmitting said commands, including said command execution time specification to each component from a central controller via respective transmission paths of identical lengths.

9. A method as claimed in claim 8 comprising taking the respective identical lengths of said transmission paths into account when temporally synchronizing the respective local clocks.

10. A method as claimed in claim 1 comprising transmitting said commands, including said command execution time specifications, via a ring-shaped transmission structure, to which the respective components are connected, from a central controller by transmitting two synchronization signals from said central controller in opposite directions via said ring-shaped transmission structure.

11. A method as claimed in claim 10 comprising defining an identical point in time for all of said local clocks as a middle point in time between respective receipt of said two synchronization signals at each component, by:

upon receipt of a first of said two synchronization signals at each component, resetting the local clock thereof to a starting point in time;

upon receipt of a second of said two synchronization signals by each local component, halving the local clock in that component; and

at said central controller, setting a master clock to a middle point in time between transmission and reception of said two synchronization pulses to and by said controller.

12. A method as claimed in claim 1 comprising transmitting said commands to the respective components in a sequence in which the respective commands are to be executed.

13. A method as claimed in claim 1 comprising transmitting said commands to the respective components independently of a sequence in which the commands are to be executed.

14. A method as claimed in claim 1 comprising, at each component, storing the commands in a first memory at respective command addresses in said first memory;

for the respective commands stored in said first memory, storing the respective command execution time specifications thereof in a second memory at respective command execution time specification addresses in said second memory that coincide with the respective command addresses in said first memory; and

when the clock time at the local clock at said component coincides with any of the respective command execution time specifications stored in said second memory, outputting the command execution time specification address thereof from said second memory to a processor at said component and, from said processor, then retrieving the command from said first memory at the command address in said first memory that coincides with the command execution time specification address output from said second memory.

15. A method as claimed in claim 1 comprising, at each component, storing said commands in a FIFO memory, and comparing the command execution time specification of a first command stored in said FIFO memory with a current clock time of the local clock at that component, and executing said first command when the command execution time specification thereof coincides with said current clock time.

16. A method as claimed in claim 1 comprising, at each component, storing said commands in a command memory, sorted according to the respective command execution time specifications thereof, in sequential read addresses, and executing said commands by reading the respective commands from said command memory at said read addresses.

17. A method as claimed in claim 16 comprising reading a command from the respective read address thereof when the current time of the local clock at that component coincides with the command execution specification time of the command.

18. A method as claimed in claim 1 comprising employing, as said components of said imaging system, components selected from the group consisting of components of a magnetic resonance tomography system, components of a computed tomography system, and components of an AX system.

19. A method as claimed in claim 1 comprising physically spatially separating the respective components in said imaging system.

20. An imaging system comprising:

a plurality of components that respectively control operation of respective units that collectively operate to generate a medical image, each of said components comprising a local clock, a component processor, and a memory;

a computerized controller configured to temporally synchronize the respective local clocks of said components in said imaging system, by transmitting commands to the respective component processors and including in the respective commands a command execution time specification that specifies a point in time at which the command should be executed that includes the respective command execution time specification;

each component processor being configured to receive the respective commands transmitted thereto and to store the respective received commands in the memory at that component, as stored commands; and

each component processor being configured to automatically retrieve and execute a stored command when a point in time at the local clock at that component coincides with the command execution time specification of the stored command.

21. An imaging system as claimed in claim 20 wherein said components are selected from the group consisting of transmitters in said imaging system and receivers in said imaging system.

22. An imaging system as claimed in claim 20 wherein said commands have a time resolution associated therewith, and wherein the respective local clocks are configured with a local clock time resolution sufficient to execute the respective commands according to the time resolution of the commands.

23. An imaging system as claimed in claim 20 wherein said local clocks are temporally synchronized with a reproducible phase that causes all of the local clocks to indicate an identical clock time, by said local clocks being configured to synchronize with each other or by said controller being configured to synchronize said local clocks with a reference clock.

24. An imaging system as claimed in claim 20 wherein said controller is configured to temporally synchronize the respective local clocks by placing the respective local clocks in communication with a common system clock.

25. An imaging system as claimed in claim 20 wherein said controller is configured to temporally synchronize the respective local clocks by providing a transmission clock in a data stream transmitted to the respective components.

26. An imaging system as claimed in claim 20 wherein said controller is a synchronization master that transmits said commands, including said command execution time specification, to the respective local clocks, the respective transmissions from the synchronization master to the respective local clocks each having a signal delay associated therewith, and wherein the respective component processors are configured to automatically take said signal delay into account when temporally synchronizing the respective local clocks.

27. An imaging system as claimed in claim 20 wherein said controller is configured to transmit said commands, including said command execution time specification to each component from a central location via respective transmission paths of identical lengths.

28. An imaging system as claimed in claim 27 wherein the respective component processors are configured to take the respective identical lengths of said transmission paths into account when temporally synchronizing the respective local clocks.

29. An imaging system as claimed in claim 20 wherein said controller is a central controller and wherein said components form a ring-shaped structure, said central controller being configured to transmit two synchronization signals from said central controller in opposite directions via said ring-shaped transmission structure.

30. An imaging system as claimed in claim 29 wherein each component processor is configured to define an identical point in time for all of said local clocks as a middle point in time between respective receipt of said two synchronization signals at each component, by:

upon receipt of a first of said two synchronization signals at each component, resetting the local clock thereof to a starting point in time;

upon receipt of a second of said two synchronization signals by each local component, halving the local clock in that component; and

at said central controller, setting a master clock to a middle point in time between transmission and reception of said two synchronization pulses to and by said controller.

31. An imaging system as claimed in claim 20 wherein said controller is configured to transmit said commands to the respective components in a sequence in which the respective commands are to be executed.

32. An imaging system as claimed in claim 20 wherein said controller is configured to transmit said commands to the respective components independently of a sequence in which the commands are to be executed.

33. An imaging system as claimed in claim 20 wherein each memory comprises a first memory and a second memory and wherein each component processor is configured to:

store the commands in the first memory at respective command addresses in said first memory;

for the respective commands stored in said first memory, store the respective command execution time specifications thereof in the second memory at respective command execution time specification addresses in said second memory that coincide with the respective command addresses in said first memory; and

when the clock time at the local clock at said component coincides with any of the respective command execution time specifications stored in said second memory, retrieve the command execution time specification address thereof from said second memory to then retrieve the command from said first memory at the command address in said first memory that coincides with the command execution time specification address output from said second memory.

34. An imaging system as claimed in claim 20 wherein each memory is a FIFO memory, and wherein each component processor is configured to compare the command execution time specification of a first command stored in said FIFO memory with a current clock time of the local clock at that component, and to execute said first command when the command execution time specification thereof coincides with said current clock time.

35. An imaging system as claimed in claim 20 wherein each component is configured to store said commands in the memory, sorted according to the respective command execution time specifications thereof, in sequential read addresses, and to execute said commands by reading the respective commands from said memory at said read addresses.

36. An imaging system as claimed in claim 35 wherein each component processor is configured to read a command from the respective read address thereof when the current time of the local clock at that component coincides with the command execution specification time of the command.

37. An imaging system as claimed in claim 20 wherein said units are selected from the group consisting of units of a magnetic resonance tomography system, units of a computed tomography system, and units of an AX system.

38. An imaging system as claimed in claim 20 wherein the respective components are physically spatially separate from each other.