Optima MR450w BASE 1.5T System Service Methods
5690012-2EN Revision 3
Object ID: 00000018WHA30BE62GYZ
Topic ID: id_2001481 Version: 6.24
Date: Jun 20, 2021 10:59:03 PM

Calibrating High Order Eddy Current (HOEC)

Prerequisites


Personnel requirements
Required persons	Preliminary requirements	Procedure	Finalization
1	-	60 minutes	10 minutes


Tools and test equipment
Item	Quantity	Part number	Manufacturer
LVShim Phantom Inner Sphere	1	2274476	-
LV Phantom Small Half Assembly	1	2306642	-
LV Phantom Big Half Assembly	1	2306645	-
Universal Phantom Pad	1	46-328383P1	-

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.
Do not use foam service filler panels for HOEC procedures.


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.

Warning

Poisonous substance

Green phantoms contain nickel, a suspected carcinogen.

Do not ingest. Dispose of hazardous waste according to state and federal regulations.

Warning

Poisonous substance

Pink phantoms contain silicon oil, a potentially poisonous substance.

Do not ingest. Dispose of hazardous waste according to state and federal regulations.

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.