Topics covered in this article include:

Introduction

MPC is a Varian tool used with the Isocal phantom to verify the operation of TrueBeam and Halcyon linacs.

The following beam check tests are provided:

Beam output constancy check
Beam profile constancy check
Beam center shift

Additionally the following geometry tests are provided:

Treatment isocenter size/location
The coincidence between treatment isocenter and MV and kV imaging isocenters
Collimator rotation offset
Gantry positioning accuracy
Couch position accuracy up to 6 degrees of freedom
MLC leaf position and reproducibility
Jaw position accuracy

Users should follow Varian recommendations on the use of MPC in addition to the existing QA checks.

Prerequisites

Before attempting to configure the MPC Import, ensure that the following is available:

the latest Equipment Hub version is installed
the serial number of the linac
the location of the MPC files
the list of energies that will be captured

Connecting a Varian MPC Device

Support for Varian MPC software is version specific. If your version is not listed in the table below, please contact our support team for guidance to set up the MPC import:

Machine	MPC Version
TrueBeam	2.5, 2.7, and 3.0
Halcyon	all

Before performing this configuration ensure that the Varian MPC software is installed and functioning correctly. In the software, the MPC import will need to be set up from the “Manage - Measurement Devices” page.

Navigate to the "Manage - Measurement Devices".
Click the + Add Device button.
Enter a description for the MPC in the Device Label field, for example: MPC TrueBeam 1021.
Click the Active radio button.
Optionally add a description in the "Device description" field.
Select MPC Import from the "Device Type" drop down menu.
Enter the file name for the MPC results file. Typically the file name is Results.csv.
Enter the full path to the folder that contains the MPC files.
If using a single measurement device for multiple linacs or there is some other need to search below the top level of folders, check the Recursive search check box. Warning: this could significantly increase the time needed to access MPC files.
Select the correct Equipment Hub service from "Equipment Hub" drop down menu.
Click the Add Device button
Navigate to the "Manage Schedule Configurations" page. Select the schedule that the MPC Import device will be used with and click the Schedule Settings button for that schedule.
Click the Edit Schedule Settings button.
Under the MPC Import section, pick the correct Equipment Hub from the first drop down menu.
Under the "External Equipment Database" section, pick the correct measurement device from the second drop down menu.
Add the serial number for the linac in the "Serial Number" field. The serial number is required to pull the correct files.
Under the "Default Energies" section, select the checkbox for each energy that will be imported from MPC. As each energy is checked, a text box will be created, enter the energy as it is shown in the folder. See the example below where the energy is circled in red:
Click the Save Machine Schedule Settings button.

Adding Tests to QA Templates

MPC Import tests can be added to QA templates in the same manner as selecting other tests when setting up your QA templates and schedules. MPC tests are listed under the MPC Import section. The MPC Import tests can be combined with other test types to customize the template.

The recommended tests vary by the version of MPC used. See the following sections for test recommendations.

TrueBeam MPC Version 2.5

Below is the test selection window under the template creation page. The recommended tests for use with TrueBeam MPC version 2.5 are selected in the graphic. Note that MPC configurations vary and not all tests may be available at all facilities.

MPC_2.4.jpg

TrueBeam MPC Version 2.7

Below is the test selection window under the template creation page. The recommended tests for use with TrueBeam MPC version 2.7 are selected in the graphic. Note that MPC configurations vary and not all tests may be available at all facilities.

MPC_2.7.jpg

TrueBeam MPC Version 3.0

Below is the test selection window under the template creation page. The recommended tests for use with TrueBeam MPC version 3.0 are selected in the graphic. Note that MPC configurations vary and not all tests may be available at all facilities.

Halcyon MPC All Versions

Below is the test selection window under the template creation page. The recommended tests for use with TrueBeam Halcyon MPCs are selected in the graphic. Note that MPC configurations vary and not all tests may be available at all facilities.

Importing MPC Data

Once the schedule containing the MPC Import tests are created and configured, performing QA and importing data is fast and simple.

Open the Schedules page.
Click the schedule containing the MPC Import tests you wish to perform. The data entry page will open.
At the top of the page in the "QA Device date filter" box, set the date to the date for which you wish to import data and click the Get MPC Import results button.
All data for a given date will be imported. If more than one MPC check has been run on the given date, only the most recent will be included on the report. If no data exists, a notification will appear saying no MPC results could be found. In this case, check the date, the serial number in the Schedule settings and then the path in the Equipment Hub setup.

Setting Tolerances

Typically tolerances will not be set in TotalQA for MPC imports. The import includes the action limits set by Varian. The action limit works the same way other tolerances do. The import does not include warning limits so they must be calculated. Varian sets warning limits to 90% of the action limit but unlike TotalQA uses greater than or equal to the warning limit. To ensure that TotalQA flags limits the same way as Varian, the warning limits are set to (0.9*action limit) -0.001.

The warning and action limits from Varian may be overridden by setting them in TotalQA.

Troubleshooting

Please see the following articles to troubleshoot common problems: