SIGNA MR355 / SIGNA MR360
Service Manual
5856356-3EN Revision 5.0
Basic Service Documentation. Copyright General Electric Company.
Object ID: 00000018WIA30307E20GYZ
Topic ID: id_13106786 Version: 3.0
Date: Aug 29, 2019 1:36:11 AM

Isocenter Calibration (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
1.5T DQA Phantom w Head Loader	1	-	2321556	-
1.5T Split Head Coil ASM	1	-	2341973	-

Table 3. Safety

DANGER

Poison Hazard!

Signa 1.5T, 1.0T, And 0.7T System Phantoms Contains 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 Contains Silicon Oil, A Suspect Carcinogen

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

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	-	-

Preparation for Scan

About this task

The electrical isocenter is the point where the x, y and z gradients are nulled. It is very important that this point be accurately located in order to pass the image quality tests. The procedure uses the DQA phantom and Daily Quality tool for analyzing the data. The Daily Quality tool analyzes the DQA image and determines the optional z direction offset that is needed to center the landmark at the z isocenter. The tool optionally updates the isoVectorZ value contained in the system configuration file (MRconfig.cfg). If you choose to update the system configuration file, you must reboot the system. Note: For TwinSpeed, the entire procedure only needs to be run on one gradient mode, Whole Body (WB). Running the procedure on both WB and ZOOM will not hurt, but is just not necessary.

Procedure

Place head coil on cradle and plug coil in.
Place DQA phantom in head coil.

Note:
Phantom Placement is Critical. Please take the time to make sure that the phantom is in alignment with the bore and the 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 Tool Setup.

Start the DQA Tool- Prepare for DQA Analysis (Isocenter Cal)

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 give an accurate isocenter location. If the image is skewed more than a few degrees, it will still be analyzed, but the adjust values for isoVector-Z may be inaccurate. In this case, the phantom should be repositioned and another scan performed.

Procedure

Select Utilities Desktop. Refer to Figure 1.

Figure 1. Utilities Desktop
Select Cal/Checks from the Service Desktop Manager.
Select Service Browser from Service Desktop Manager (CSD). Refer to Figure 2.

Figure 2. Service Browser
Select the Calibration tab. Refer to Figure 3.
Select DQA Calibration from the calibration list. Refer to Figure 3.
Select Click here to start the tool. Refer to Figure 3.

Figure 3. MR Service Desktop

The Daily Quality Assurance Test tool will appear. See Figure 4 .

Figure 4. Calibration Tool
Enter “2” and press the Enter key.
Select the Test Option – type 1 [1= Iso center (Z) Calibration] Enter.

The analysis tool will automatically set up scan parameters and will perform the scan. See Figure 5.

Figure 5. Analysis Tool

After the scan is complete the tool will automatically launch the analysis and display the results. See Figure 6.

Figure 6. Analysis Results
If adjustment is required then type Y to update isoVectorZ value in MRconfig.cfg.

Note:
TPS will automatically reset after update to MRconfig is complete.
Type “Y” when prompted to perform the Final Test run. See Figure 7.

Figure 7. Final Test Run
Review the test results to see if the calibration passed or failed. See Figure 8.

Note:
If passed then go to Step 12, if failed checked the phantom centering and run the calibration again.

Figure 8. IsoCenter Calibration Results
Enter Test Step Option 6 when calibration is complete, then press Enter to quit.

Finalization

Procedure

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