• Discovery MR750 3.0T System Service Methods
  • 5690009-2EN Revision 4
  • Object ID: 00000018WHA30BE62GYZ
  • Topic ID: id_2001481 Version: 7.0
  • Date: Nov 2, 2021 1:33:29 PM

Calibrating High Order Eddy Current (HOEC)

Use HOEC to characterize the time-dependent magnetic field errors in the bore up to at least the third order.

Prerequisites

Personnel requirements
Required personsPreliminary requirementsProcedureFinalization
1-60 minutes10 minutes
Tools and test equipment
ItemQuantityPart numberManufacturer
LVShim Phantom Inner Sphere12274476-
LV Phantom Small Half Assembly12306642-
LV Phantom Big Half Assembly12306645-
Universal Phantom Pad146-328383P1-
Note: The LV Phantom Small Half Assembly, LV Phantom Big Half Assembly, and LVShim Phantom Inner Sphere are used for systems running software versions DV26.0 or earlier. The LVShim Phantom Inner Sphere alone is used with the Universal Phantom Pad for systems running software versions DV29.1 or later.
Required conditions
Confirm that grafidy eddy current calibration is complete.
Remove all coils from the cradle and phantoms from the bore.
Safety

Before working in any GE Healthcare MR suite or performing any GE Healthcare service procedure, you must:

  • Have read and understood all hazard conditions and safety requirements in the latest revision of the GE Healthcare MR Service Safety Manual (5452735).
  • Have successfully completed all relevant GE Healthcare Environmental Health and Safety (EHS) courses (or for non-GE employees, equivalent workplace training courses).
  • Comply with all site-specific training and workplace safety requirements.

If you have any safety concerns at any time, do not begin work or immediately stop work and move to a safe location. Immediately contact your supervisor or site safety officer for instructions on how to proceed.

About this task

Use the High Order Eddy Current (HOEC) procedure to characterize the time dependent magnetic field errors in the bore up to at least the third order. This calibration works in conjunction with Grafidy eddy current calibration, which adjusts and compensates the short, long, and very long time constant eddy currents for both linear and B0 terms. Run the HOEC calibration anytime after Grafidy is run.