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Calibrating High Order Shim (HOS)
This procedure creates High Order Shim (HOS) reference maps characterizing the fields created by the HOS windings. These maps are used by the HOS feature.
Running High Order Shim (HOS) calibration

Adjustments/Calibrations
- System
  - B0 Drift Calibration
  - Doing DQA calibration
    The DQA tool determines proper gradient polarity and proper gradient wiring by scanning a series of axial and coronal images of the DQA III phantom.
  - Troubleshooting the Daily Quality Assurance (DQA) II tool
    If problems are encountered while using the Daily Quality Assurance (DQA) calibration procedure, refer to the following guidelines for troubleshooting.
  - Dual drive quadrature tool
  - Doing the Echo Planar Test
  - Deionization procedure
  - HIS/RIS Setup and Troubleshooting
  - Calibrating High Order Shim (HOS)
    This procedure creates High Order Shim (HOS) reference maps characterizing the fields created by the HOS windings. These maps are used by the HOS feature.
    - HOShim Reference Map Creation and Verification for DV26.0 or earlier
    - Configuring for systems running DV29.1 and later
    - Running High Order Shim (HOS) calibration
    - Doing a check scan
      A check scan is done at the conclusion of many procedures. This functional check assures the unit is in good clinical working order.
  - ICN On/Off procedure for Sun 4100, 4170, and Dell R620
  - LVShim Procedures
  - Running LVShim
    The objective of the LVShim tool is to fine-tune magnet homogeneity.
  - Running LVShim - Gradshim
  - Running LVShim in Auto mode
  - Running LVShim in Manual mode
  - System gain calibration
    Head and body system gain calibration.
- Gradient
- Radio Frequency (RF)
- Magnet Enclosure
- Patient Table
- Global Operator Console (GOC)
- Spectroscopy

Discovery MR750 3.0T System Service Methods
5690009-2EN Revision 4
Object ID: 00000018WIA30595E50GYZ
Topic ID: id_2028272 Version: 1.4
Date: Sep 9, 2020 9:36:17 AM

Running High Order Shim (HOS) calibration

Procedure

Start the HOS procedure/calibration:
- (For restricted service tools) Make sure the service key is installed.
  1. On the Calibration tab, select Calibration > Install And Calibration Wizard.
  2. Select HOShim Procedure. If HOShim Procedure is not available, refer to Installation and Calibration Wizard for instructions.
- (For non-proprietary service tools) Open the Common Service Desktop.
  1. On the Calibration tab, select Calibration Tools > HOS Calibration.
    Figure 1. HOS Calibration option
  2. Click Click here to start this tool.
    Figure 2. HOS Calibration tool
    Callout Name Description
    1 Status bar The current status of the HOS calibration procedure
    2 Scan Starts the HOS calibration
    3 Abort Stops the HOS calibration
    4 Exit Closes the HOS calibration tool
  3. Click Scan.
    The system prescans first, then scans. There are multiple scans in this sequence with no user interaction required. The scan will take approximately 50 minutes to complete.
    When the scan is complete, a dialog box appears. If the calibration is successful, the values show in green and a dialog box appears indicating High Order Shim Calibration Passed.
  4. Click OK.
    Note: If the value is red, this indicates the calibration failed. A dialog window appears with the following message: High Order Shim Calibration Failed. Check High Order Shim Power Supply.
    Figure 3. High Order Shim Calibration Passed dialog box
Click Exit.