SIGNA MR355 / SIGNA MR360
Service Manual
5856356-3EN Revision 5.0
Basic Service Documentation. Copyright General Electric Company.
Object ID: 00000018WIA30B67E20GYZ
Topic ID: id_13106787 Version: 3.0
Date: Aug 29, 2019 1:36:43 AM

Gradient Calibration (GradCal) - Auto Mode

Prerequisites

Table 1. Personnel requirements
Required persons	Preliminary requirements	Procedure	Finalization
1	Not Applicable	30 minutes	Not Applicable

Table 2. Tools and test equipment
Item	Quantity	Effectivity	Part number	Manufacturer
DQA Phantom W Head Loader	1	-	2371512	-
1.5T DQA Phantom With Head Loader	1	-	2322997-2	-
1.5T Split Head Coil	1	-	2341973	-

Table 3. Safety

DANGER

Poison Hazard!

Signa 1.5T, 1.0T, And 0.7T System Phantoms Contain Nickel, A Suspect Carcinogen

Do Not Ingest. Dispose Of As A Hazardous Waste According To State And Federal Regulations

DANGER

Poison Hazard!

Signa 3.0T System Phantoms Contain Silicon Oil, A Suspect Carcinogen

Do Not Ingest. Dispose Of As A Hazardous Waste According To State And Federal Regultaions

Table 4. Required conditions
Condition	Reference	Effectivity
Signa Software operational	-	-
First image obtained	-	-
Alignment lights have been physically aligned	-	-
Table has been calibrated per “Longitudinal Drive System” calibration procedure	-	-

About this task


Last Update	03/28/2006

Preparation for Scan

About this task

In this procedure, the strength of the gradient fields are calibrated by modifying the control variables cfxfull, cfyfull, and cfzfull. A separate scan will be taken to calibrate each of the three gradient fields (x, y, and z). For TwinSpeed, the whole procedure must be repeated for each gradient mode (GradMode) separately, Whole-Body (WB) and Zoom (ZM) gradients.

Procedure

Place head coil on cradle and plug coil in.
Place the DQA phantom in head coil.
Turn on alignment lights.
Move the cradle to center the phantom with the alignment light.
With laser light on center of phantom, press the Landmark button.
Press Move to Scan. (Head Coil should automatically move to the center of the magnet.
Go back to the GOC and resume scan setup.

Start the DQA Analysis Tool- Prepare for DQA Analysis (GradCal)

About this task

The Daily Quality tool analyzes the DQA image to determine if the image is skewed in the x direction (x-y planes). Analysis performed on an image with a few degrees of skew will still give an accurate GradCal value.

Procedure

Select Utilities Desktop. Refer to Figure 1

Figure 1. Utilities Desktop
Select Service Browser from the Service Desktop Manager (CSD).
Select the Calibration tab.
Select the DQA Calibration from the calibration list.
Select Start the DQA Calibration by clicking on the Click here to start this tool. Refer to Figure 2.

Figure 2. Starting Gradient Calibration

Note:
The Daily Quality Assurance Test tool should appear. Refer See Figure 3.
Select Test Mode Option: Type 2 [2= Auto Mode], Enter.

Figure 3. DQA Calibration Tool
Select Test Option: Type 5 [5= GradCal All Three Axis], Enter.
The Calibration tool will begin and pause requiring that you to make a gradient coil choice. Refer to Figure 4.

Figure 4. DQA Calibration Tool
Select appropriate mode for Twin Speed Systems (recommend to use option B = Both the Modes). The tool will scan and adjust in the following order: X-Whole; X-Zoom; Y-Whole; Y-Zoom; Z-Whole; Z-Zoom.

The system will start scanning. The sequence of events is prescan, then scan. The system will re scan if adjustments are necessary. Select Y to update GradientConfig.cfg. See Figure 5.

Figure 5. DQA Calibration Tool
You must select Y to perform the final test scan. See Figure 6.

Figure 6. DQA Calibration Tool
When complete, you will see the main menu. Type 6 to select option [6=Quit], Enter. Then press Enter at the prompt press Enter to quit ->. See Figure 7.

Figure 7. DQA Calibration Tool

Finalization

Procedure

Remove all phantoms and coils from the magnet
Return the scanner to normal operation