QA Tests

A QA test requires taking a measurement acquired in well-defined conditions, analyzing it and comparing the analysis outcomes to expected values. Expected values can be the analysis outcomes of a measurement taken in the past, or values entered by the user based on some expectation. QA tests are used to assess the quality of beam delivery, which is a prerequisite for patient treatment.

The comparison is quantitative: analysis parameters are extracted from the measurement and compared to the expected values.

Four QA test types are supported:

• Energy Validation
• Light / radiation field coincidence
• Output constancy
• Profile constancy

These tests are listed together with the corresponding analysis parameters in the table below. For every analysis parameter a test result is generated based on warning and error tolerances.

Default QA Tests - Defaults

To speedup test execution, the user can customize the default value for parameters shared by all test
types:

• Select a Test type from the list. (2)
• Click the Edit button to change the shared parameters (2):
  • Field size, crossline (LR) and inline (RT)
  • Gantry angle
  • Delivered MU
  • SDD
  • Collimator angle
• Click Save to confirm the changes.
• Some defaults can be test specific. For each test type, the Expected values and tolerances (3) can be edited from the provided factory defaults. Click the Edit button to change the parameters.
• Click Save to confirm the changes.
• Each Test can be returned to the default settings by clicking the Reset to factory settings button (4).

Test Type

• Select the test type:
  • Energy validation
  • Light/radiation field coincidence
  • Output Constancy
  • Profile constancy

Energy validation

• On the Execution page, click the Create test button.
• Select Energy validation.

• Enter the necessary parameters.

  

• Click Create Execution. The new QA test will appear in the list on the Execution page.

Light/radiation field coincidence

• On the Execution page, click the Create test button.
• Select Light/radiation field coincidence.

• Enter the necessary parameters.

  

• Click Create Execution. The new QA test will appear in the list on the Execution page.

Output Constancy

• On the Execution page, click the Create test button.
• Select Output constancy.

• Enter the necessary parameters.

  

• Click Create Execution. The new QA test will appear in the list on the Execution page.

Profile constancy

• On the Execution page, click the Create test button.
• Select Profile constancy.

• Enter the necessary parameters.

  

• Click Create Execution. The new QA test will appear in the list on the Execution page.

Specific Test Conditions

BEAM SETUP

• Optional: Specify location (this will pre-filter possible machines).
• Specify machine and energy.

• Optional: Change default settings for field size, gantry angle, collimator angle, SDD, plate (i.e., a phantom), and delivered MU.

  DEVICE SETUP

• Optional: Set device position (on couch / on gantry), device rotation.

• Optional: Set accessories available for the specified machine and energy (wedge or applicator).

  In the specific case of Energy validation, the phantom is automatically set to the energy plate of the selected energy. It cannot be changed.

  PROTOCOL (Optional and only for Profile constancy test)

• Change default settings for profile analysis protocol and directions of profiles to be tested.

  DIRECTIONS (Optional and only for Profile constancy test)

• Select which directions to include in the measurement (inline, crossline, rising diagonal, falling
  diagonal).

  ADDITIONAL PARAMETERS

• Add Notes to the test. Notes can also be edited and added later.
• For Light/radiation field one can specify:

  • Field width algorithm

    If the algorithm Use signal level is selected, the user can additionally specify the signal level
    (relative to the pixel in the center (CAX)).

  • High resolution

    Signal from pixels slightly outside the main axes can be used to increase resolution in the typical penumbra regions of reference fields. In high resolution mode these pixels are considered along main axes. High resolution mode shall not be used if field edges lie upon central axes.

• For Profile constancy one can specify:

  • High resolution

    Signal from pixels slightly outside the main axes can be used to increase resolution in the typical
    penumbra regions of reference fields. In high resolution mode these pixels are considered along
    main axes. High resolution mode shall not be used if field edges lie upon central axes.

• Once all the parameters have been set, click the Create Execution button .
• The QA Test page opens.

QA Test Execution

• Optional: Select a Reference measurement (1).
  Click on the arrow to expand the Reference section.

• Select a Reference from the list of Available references by clicking the Select button for the
  Reference.

  If no References appear in the list, a Measurement can be set as a Reference in the Explorer page (Chapter 9). Return to the QA Test page and the Reference should now appear in the list.

  

• Once a Reference has been selected, it can be deselected by clicking Remove (2).

  

• Provide a Measurement to evaluate Measured values of parameters:

  • Option 1: Acquire a measurement (3)

    (Optional for test type Output constancy) Acquire multiple measurements and take their average

  • Option 2: Load an existing measurement from database (this measurement shall fit all test settings) (4)

  

• The test results will be shown in the Results area. A summary of the test results is shown to the right (5).
• Detailed test results are displayed in the table below. Click the Edit button (6) to edit the Expected values, Warning and Error Tolerances.

• Click the Save button to confirm the changes.

  If a value has been edited, a pencil icon will appear next to the edited value (7). Hover over the icon to see the original value.

  

• The Test result column displays the status of the test (8).

  • If a test result has not been evaluated, the result will say, ? NOT EVALUATED
  • For every parameter, the expected value is compared to the reference, and, in view of tolerances, a PASS / WARNING / FAIL result is generated.

  See Section 10.1 for additional information on Test result status.

  

• Optional: Add or edit a Note for the QA Test. Click the Edit button in the Note section on the left side of the screen.
• Save the test by clicking the Complete Test button . Please note, the test can be left open and completed at a later time.

• Optional: Move to the Measure workspace by clicking the Compare in measurement workspace
  button .

  The select the measurement and the reference (if applicable) are automatically moved to the Measure
  workspace so that the user can compare them in 1D plots.

  If the test is Profile constancy, the test protocol is automatically set in measure workspace too.