Topic ID: id_2001480
Version: 7.2
Date: Dec 10, 2019 2:22:30 PM

Calibrating grafidy

Grafidy adjusts and compensates short, long, and very long time constant eddy currents for both linear and B0 terms. Use the Grafidy procedure to do eddy current compensation.

Prerequisites

Personnel requirements
Required persons	Preliminary requirements	Procedure	Finalization
1	-	2 hours	5 minutes

Tools and test equipment
Item	Quantity		Part number	Manufacturer
1.5T Grafidy Kit	1	-	5135527-7
Service Filler Panel	1	-	5344577	-
Service Foam Positioner	1	-	5554839	-

Replacement parts
Item	Quantity	Part number	Manufacturer
RF coil assembly	1	5135514	-

Required conditions
DQA (Grad Cal/IsoVector2) tool within specification. See DQA calibration.

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.

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.

Grafidy adjusts and compensates short, long, and very long time constant eddy currents for both linear and B0 terms. Use the Grafidy procedure to perform eddy current compensation. Grafidy should be run in auto mode first. The oscillatory mode is also included in auto mode. If auto mode fails to bring any of the terms into specification, manual mode can be used.

Grafidy uses a dedicated pulse sequence, six-channel fixture, and Grafidy software. The Grafidy P-port connector plugs into the P2 port for transmit/receive. No additional fixtures or cables are needed.

This tool simplifies setting up the calibration and collects data from all six coils simultaneously.

Table 1

Auto mode - The Grafidy tool is initially run in auto mode. note: 3TLC/UA and 7T magnets only -XB0 and YB0 oscillatory mode is part of auto mode. The tool also picks the optimal number of oscillatory fitting terms automatically. Long XB0 and YB0 are run automatically after the oscillatory mode to confirm that the system is within spec.
Manual mode - When doing this procedure, if auto mode does not bring all the terms into specification (still red in the Result/Area table), proceed to Running Grafidy in Manual mode. note: If VLONG, LONG or SHORT terms are failing, manual mode should be run to bring the VLONG mode into specification.