• Discovery MR750 3.0T System Service Methods
  • 5690009-2EN Revision 4
  • Object ID: 00000018WIA30B84E20GYZ
  • Topic ID: id_13105860 Version: 3.1
  • Date: Sep 16, 2021 5:40:07 PM

Dual Drive Quadrature Tool

Prerequisites

Table 1. Personnel requirements
Required personsPreliminary requirementsProcedureFinalization
1Not Applicable30 minutesNot Applicable
Table 2. Tools and test equipment
ItemQuantityEffectivityPart numberManufacturer
Body Loader with Sphere Phantom1-

2371511

-
GEM Coil Phantom Foam Support1flat tables only

5404900

-

About this task

A dual drive system has two transmit channels. The DD (Dual Drive) Quadrature Tool is used to compensate for the amplitude and phase differences in the transmit channels. Amplitude and phase differences between the two channels can begin at the Exciter and be carried right up to the end of the imaging chain which is the body coil transmit. It can also be introduced at any of the intermediate passive components.

Dual Drive Quadrature Tool performs axial scans in three modes.

  • Combined mode

  • CH1 transmit, CH2 disabled

  • CH2 transmit, CH1 disabled

The Dual Drive Quadrature Tool calculates amplitude difference between CH1 and CH2 channel, and also calculates phase difference between CH1 and CH2 channel. It then updates the system calibration file with the cumulative compensation required.

Test mode without calibration is provided.

Figure 1. Flowchart of DD Quadrature Tool
Figure 2. User Interface of DD Quadrature Tool

Procedure

  1. At the scanner, remove any surface or head coil from the bore. Confirm that the cradle is at the home position.
  2. Place a body loader with sphere phantom as shown in Figure 3 as rough alignment.

    For flat table:

    • Place GEM coil foam support so that the body loader will be located at the center of the cradle.

    • Place the body loader with sphere phantom.

    Figure 3. Phantom Setup
  3. Confirm that the cradle is at the home position. If not, move the cradle to the home position.
  4. Move the cradle IN so that the in-room monitor shows 1080 mm.
    Figure 4. Alignment
  5. Adjust the body loader location so that the alignment lights hit on the cross section on the body loader (fine alignment).
  6. Press [Land Mark] button. Then, press [Advance to Scan] button.
  7. Open MR Service Desktop. Select Calibration tab, Dual Drive Quadrature, and Click here to start this tool.
    Note:

    The tool can be selected in either proprietary mode or non-proprietary mode. Figure 5 shows non-proprietary mode. For proprietary mode, select the tool from the Calibration Wizard.

    Figure 5. Invoke Dual Drive Quadrature Tool (Non-Proprietary mode)
  8. To start the DD Quadrature Tool, click [Start] button for first iteration. Scan and analysis will start. It will take about 6 minutes.
    Figure 6. Start Calibration
    Note:

    If the phantom is off-center by more than 30 mm, the following message will be displayed. Set up the phantom again if this message is shown.

  9. After the first iteration is completed, the calibration result will be pass or fail, as described below.
    1. If calibration is passed as in Figure 7, click [Quit] to complete the calibration. Go to Finalization. (1).
    2. If the calibration is failed at first iteration as in Figure 8, the next iteration will start automatically until the values are in specification until iteration 3.
    Figure 7. Pass Case
    Figure 8. Fail Case at First Iteration
  10. If the calibration passes within three iterations, click [Quit] to exit the tool.

Finalization

  1. Restore the phantom and cradle.
  2. Perform a body scan.