• Discovery MR750w and SIGNA™ Architect T 3.0T System Service Methods
  • 5690002-2EN Revision 4
  • Object ID: 00000018WHA30A3C6GYZ
  • Topic ID: id_2001851 Version: 8.3
  • Date: Nov 30, 2021 1:53:39 PM

Doing system gain calibration (DV27 or later)

Prerequisites

Personnel requirements
Required personsPreliminary requirementsProcedureFinalization
15 minutes10 minutes2 minutes
Tools and test equipment
ItemQuantityPart numberManufacturer
Body TLT Sphere for 3.0T (Pink Solution)12360025-
Body TLT Loader for 3.0T12360037-
Head TLT Loader for 3.0T12360031-
Head TLT sphere for 3.0T (pink solution)12359877

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3.0T split-top head coil15182872-
GEM coil phantom foam support15404900-
Curved adapter panel15401439-

About this task

System gain calibration determines the body and T/R (transmit/receive) head recon scale factors that will achieve a known level of image intensity when you use the body and T/R head coils with a known phantom solution and protocol. The goal is that when the same solution or tissue is scanned in the standard body and T/R head coils with the same protocol, those tissues will have approximately the same image intensity level on a given system and between systems of like type.

This calibration accounts for differences in body receive coil and T/R head coil sensitivity, preamp gains, cable loss, receiver gain, and other factors. The calibration must be done on the body at least once to calibrate those paths.

Procedure

  1. Position the head sphere in the head loader and fasten the strap. Position the head loader on top of the head loader positioner in the head coil so the loader's black center line lies directly below the head coil's superior/inferior center marker.
    Note: 3.0T spheres are pink. 1.5T spheres are light green.
    Figure 1. Positioning head sphere loader
    Figure 2. Landmark head sphere
  2. Make sure the top section of the split-top coil is properly oriented. Align the arrows on the NOTICE labels for the correct orientation.
  3. Properly position the head sphere and loader as previously noted.
  4. Landmark on the center line of the head loader, but do not advance to scan.
  5. Run the cradle in so the display reads 1135 mm.
    Figure 3. Distance between head coil landmark and center mark on body loader (flat table)
    ItemDescription
    1Distance of 1135 mm between the landmark on the head coil and the center-mark on the body loader
  6. Put the body loader on the Service Foam Positioner. Turn on the alignment light and then position the body loader on the cradle so that the alignment light is properly centered on the loader crosshair.
    Do not landmark after completing this step.
  7. Press Advance to Scan.
  8. Start the system gain calibration tool from the Common Service Desktop: Select Calibration > System Gain Calibration and click Click here to start this tool.

    The SNR and System Gain Calibration Tool window shows.

  9. Note: You can enter text into the Comments field.
    Keep HEAD & BODY as the Coil value.
  10. Select the Run System Gain Calibration checkbox.
  11. Select the Start button.
    Figure 4. Run system gain calibration (example)

    Result

    The calibration starts. After it is complete, the tool window shows that the calibration is completed. If adjustments are necessary, the system asks, Do you want to save the recon scale factor?
  12. Click Yes.

    Result

    The calibration is complete.

Finalization

Do a SaveInfo to save the new Recon Scale values.