myQA FastTrack - Applications

General Procedure

• Set up the devices (see Section 2.1)
  Please see Section 4.3.2. in myQA Platform Instructions for Use for information on performing uniformity and absolute calibrations. The user uniformity correction wizard is available for the MatriXX Resolution and myQA SRS.
• Perform measurements (see Section 2.2)
• Analyze the measurement data in the corresponding workspace (see Section 2.5):
  
  • Profile analysis in the Profiles workspace
  • Energy verification in the Energy workspace
  • Startup stability in the Startup workspace

 

Setting up Devices

In this section, the device installation for measurements are described. The device setup in the software is
described in Section 4.3, myQA Platform Instructions for Use. Normally, the device configuration in the SW is not necessary for the measurements in the FastTrack. However, it is recommended to properly configure the machine and detector to obtain correct data analysis, especially for the profile analysis.

 

IMPORTANT NOTICE. PREPARE THE DEVICE

• Check whether the measurement device is properly connected and ready to use.
• Make sure that the device is in the correct position.
• Check the connection between the device and the PC (WLAN, Ethernet, or direct connection).
• Clean the surface of the device of any contamination.

IMPORTANT NOTICE. DEVICE SETUP AND MEASUREMENT CONFIGURATION

Setup of measurement devices and device configurations in the SW should be done by experienced users or under the supervision of an experienced user to ensure the device and SW are properly prepared for measurements.

CAUTION. REPEAT ABSOLUTE CALIBRATION REGULARY
Repeat the absolute calibration regulary. The calibration used should not be older than 3 months.

CAUTION. WARM-UP AND BACKGROUND MEASUREMENTS

Please ensure an adequate warm-up period of 30 minutes before taking measurements. A background measurement is necessary for corrected readings. For more information on setting up the device, see the specific device's manual.

 

Measurement Devices

The following dose measurement 2D detectors can be used in myQA FastTrack for photon and electron beams:

• StarTrack
• myQA SRS
  Note: The myQA SRS device is only supported for Measurements in myQA FastTrack.
• 2D detectors: MatriXXEvolution, MatriXXFFF, MatriXX Resolution, or MatriXX AiR
  Note: MatriXXEvolution and MatriXXFFF support the wired Gantry Angle Sensor (GAS).
           MatriXX Resolution supports the wireless Gantry Sensor + (GS+).
           MatriXXFFF is optimized for the flattening filter-free beams. Only supported by myQA Patients.
• Dolphin detector, a 2D transmission detector

Note: Please refer to the corresponding manuals for detailed information including device description,                     installation, and setup instructions.

         Please refer to the COMPASS User’s Guide for the information including device description,                             installation, and setup instructions of the Dolphin detector.

 

Installing a Detector

• StarTrack and MatriXX
  The setup of StarTrack / MatriXX is the same for all type of measurements. They can be mounted on the gantry or placed on the patient couch / table.
  Please see the corresponding device manuals for instruction on mounting a device.
• myQA SRS: The myQA SRS system can be placed on the patient couch / table (see Section 3.4.2. in myQA SRS Instructions for Use)
• Dolphin: For mounting the Dolphin detector on a gantry, please see COMPASS User’s Guide.

 

Orientation of StarTrack / MatriXX in a LINAC

WARNING. MEASUREMENT DEVICE ORIENTATION

StarTrack / MatriXX can be placed in different orientations under a LINAC. It will affect the detector settings in the SW (Measurement configuration dialog > Detector tab > Rotation box, see Section 2.2.4, myQA FastTrack Reference Guide). The measurements for Output Calibration and QA tests should be the same. Otherwise, the Output Calibration may be incorrect and lead to wrong dose delivery and wrong results in QA tests.

 

The following drawings show the possible orientation of a table mounted detector relative to the LINAC. A clockwise rotation yields a positive value of angle.

 

Using Energy Verification Plate

For energy verification measurement, a proper buildup plate is required. A special designed buildup plate for photon beams and electron beams are available.

 

StarTrack

Place the Energy Verification plate on the StarTrack with the same orientation as the StarTrack and insert the two alignment pins (1) in the two diagonal corners.

StarTrack

 

Wired MatriXX

Place the Energy Verification plate on the wired MatriXX detector with the same orientation as the detector and align the three edges to the corresponding lines (2) on the wired MatriXX chamber:

MatriXX^Evolution

 

MatriXX Resolution and MatriXX AiR

Place the Energy Verification plate on the MatriXX device with the same orientation as the detector and
align the three edges to the corresponding lines (3) on the MatriXX device chamber:

MatriXX Resolution

 

Procedure of Setting up a Device for Measurement (Example)

This is a myQA FastTrack measurement example for a 6 MV photon beam with a table-mounted StarTrack for the analyses of profiles, energy, and start-up behavior.

• Set the LINAC (linear accelerator) gantry angle at 0°. Place the StarTrack on the patient’s table. Ensure that the network cable and power cord are properly connected. Turn on the StarTrack.A table-mounted StarTrack at 0° orientation
• Use room lasers and StarTrack alignment markers to position StarTrack. Set SDD = 100 cm.
• Place the Photon Energy Verification plate on the active area of the StarTrack.A Photon Energy Verification Plate on a table-mounted StarTrack

 

Measurement Procedure

Preconditions: The measurement devices have been set up (see Section 2.1)

Note: With the energy verification plate and Movie/Online mode, the measurement can be used for
all three types of analysis.

The general steps to carry out a measurement follow the Measurement ribbon item order from left to right:

Measurement ribbon of StarTrack / MatriXX / Dolphin

Measurement ribbon of myQA SRS

• In the Equipment group, select the correct machine and detector, and then click Connect.CAUTION. ENSURE CORRECT WARM-UP PROCEDURE FOR ALL DEVICES
  Please ensure the device has had an adequate warm-up period before taking measurements. A background measurement is necessary for correct readings.
• Perform background measurement (see Section 5.2, myQA Platform Reference Guide for detailed information):
  • (Optional: if the sampling time needs to be changed.) Click the dropdown triangle at the lower part of the Background icon, to open the dropdown list, and then enter the sampling time. Default is 20 sec.
  • Click the icon at the upper part of the Background icon, the background measurement starts. When it finishes, the Background icon changes from red to green color.

          Note: When the MatriXX Resolution and or myQA SRS device is turned on, it automatically performs                       background measurement. The MatriXX Resolution will continue to take background                                       measurements every 20 seconds. Be aware that the automatically measured background is only                     used for compensation; defect pixels will not be checked, and thus they will not be removed in                       the analysis.

           CAUTION. MEASURE A BACKGROUND AT LEAST ONCE BEFORE ANY MEASUREMENTS
           Even if the background icon shows that the background has been measured ( ), at least manually               measure the background once at the beginning of the measurement session so that the defect                   pixels are identified and removed in the analysis.

• If the gantry angle sensor is used, click the Angle Sensor icon, and then follow instructions in Section 6.2, myQA Platform Instructions for Use, to set up the gantry angle sensor for calibration.
• Click the Settings icon to open the Measurement configuration dialog and define the correct settings in the Machine, Detector, Calibration, and Beam detection tabs.
  For example:
  • In the Machine tab: energy = 6 MV, inline/crossline field size = 250.0 mm or as required.
  • In the Detector tab: Rotation = 0°, SDD = 1000.0 mm, Buildup thickness = 40.0 mm due to the Energy Verification plate; all offsets are 0.
  • Optionally in the Calibration tab (if absolute dose is required for the profile analysis and no output calibration is available), select the Apply output calibration checkbox.
  • In the Beam detection tab: set the thresholds for beam on detection

          For the detailed configuration instructions, see Section 6.1, myQA Platform Instructions for Use.

          CAUTION. KEEP BEAM DETECTION DEFAULT SETTINGS
          It is strongly recommended to keep the Beam detection default settings (factory settings) which                are initially displayed in the Beam Detection tab, depending on the selected device. Modification of            these parameters may lead to erroneous QA results.

• Pre-irradiate the detector for the required field size and number of monitor units (e.g., MatriXX: 24.4 cm × 24.4 cm at isocenter for SDD=100 cm. Please see the respective detector Instructions for Use for preirradiation instructions).
• Click the Measurement Mode icon in the middle of the Measurement group in the Measurement ribbon and select and define a measurement mode, e.g., the Online mode (see Section 6.3, myQA Platform Instructions for Use).
  Note: Only Movie Mode is available for the myQA SRS.CAUTION: DO NOT USE THE SINGLE SHOT MODE FOR MEASURING A ROTATIONAL PLAN
  The Single shot measurement mode is not suitable for the measurement of rotational plans. Do not use the Single shot measurement mode for measuring a rotational plan.
• myQA SRS only: When performing a measurement with the myQA SRS, it is recommended to increase the Sampling time to 2 secs to reduce the noise in the frame since no integral computation is possible in this workspace.
  Open the Movie mode dropdown menu and enter the correct number in the Sampling time box.
• Set the LINAC to, e.g., 6 MV, 100 MU, 600 MU/min. Turn on the beam and click the Start icon.
• Depending on the measurement mode, the measurement stops automatically or manually. For manual stop, click the Stop icon (Once the measurement starts, the Start icon becomes the Stop icon.).

Each measurement will be added as a frame set in the Frame panel when the measurement is started. The
name of the frame set will be:

[YYYY-MM-DD hhmm]

As soon as a frame arrives from the device, it will be added to the frame set. The frame name will be: Frame [frame number]

The first frame number is 001. It increases in increments of 1 per frame.

The measured results are displayed automatically in the main area as, e.g., 2D display, profile list, and graphics (inline/crossline/diagonal, depending on the choice of the user) if the Profile tab is selected.

 

Import Files

In addition to measurements, the data for analysis in myQA FastTrack can be also imported.

Import OPG:

• Click the Import OPG icon in the Frames ribbon.
• Browse and select the desired *.opg file.
• Click Open. A Frame set with a name of OPG: [filename] will appear in the Frame panel containing one or more frames depending on the imported *.opg file.
  Dimension units defined in OPG, but not supported in myQA will be interpreted as number. However, all charge dimension unit from OPG shall be interpreted as unit less dimension.

Import Folder:

• Click the Import Folder icon in the Frames ribbon.
• Browse and select the folder containing *.opg files.
• Click Ok. A Frameset with the name of the folder will appear in the Frame panel containing the frames inside the folder.

Note: The *.opg files in a frameset must have the same energy level and thus only the folder containing files           with the same energy can be imported as a folder. Moreover, the folder path cannot contain any of the           following characters: / ? < > \ : * |. Otherwise, a popup warning will appear, and no files will be loaded:

Dimension units defined in OPG, but not supported in myQA will be interpreted as number. However, all
charge dimension unit from OPG shall be interpreted as unit less dimension.

Note: If the data measured from FFF beams is imported, it is required that the device is correctly positioned,           and the field size is limited to 20 cm × 20 cm. It is recommended to use the FFF analysis method (see             Chapter 3, myQA fastTrack Reference Guide) for analyzing the profiles of FFF beams. If a non-FFF                   analysis method is chosen, users should be cautious about results.

 

Export a Frameset or a Frame as an *.opg File

• Select a frame, or a frameset or multiple frames of one frameset to be exported in the Frame panel.
• Click the Export icon in the Frames ribbon.
• Browse and select the desired location.
• Edit the default filename in the Filename box.
• Click Save.

Only one frame, one frameset, or multiple frames within a frameset can be selected for export at one time. The frame is exported as a .opg file. The frameset is exported as a folder containing the selected multiple frames as individual .opg files. The multiple frames within one frameset are exported as individual .opg files in a folder with the frameset name as the folder name.

If the unit of the frame set is not supported by the opg format, it will be saved as relative with all values scaled relatively to the maximum value of all frames in the frameset.

 

Data Analysis

Data analysis can be done with the Profiles ribbon. Data can be the measured data (see the section above), or imported in the Frames ribbon (see Section 2.3 for details):

• Select Import in the Frames ribbon, browse and select a desired *.opg file, and then click Open.

 

Profiles Ribbon

Table 2.1. Description of the items in the Profiles ribbon

 

Group	Description
Unit*	Provides the unit options of displayed data from the dropdown box: Absolute (Count): chamber count is used as a unit. It is only available if all selected frames can provide counts. Absolute (Dose): absolute dose is used as a unit. It is only available if the all selected frames can provide dose values. Relative (Center): each profile will be scaled relative to the individual profile's central axis value. Relative (MAX): each profile will be scaled relative to the individual frame maximum value. Inflection Point (50%): each profile will be scaled to 50% dose level at its left inflection point. The graphics are updated automatically after selecting a unit. The default unit (Relative (CAX)) will be used whenever a unit change is required because of unit limitations.
Analysis	Provides a list of photon (1) or electron (2) beam analysis protocol for analysis: Protocols are pre-defined regulatory standards. For individual algorithms, see myQA Platform Reference Guide. Note: Parameters for symmetries and flatness depend on the protocol. Ensure the                 analysis protocol is correctly selected.

 

IMPORTANT NOTICE: *IF PROFILES WITH DIFFERENT UNITS ARE SELECTED FOR COMPARISON

Profiles with different units cannot be compared. Therefore, if profiles with different units are selected for comparison, the SW will automatically convert them in the relative to CAX and then display the data. The SW displays which conversion (relative to center or maximum) is used.

WARNING: ANALYSIS PROTOCOL AND RADIATION TYPE

Ensure the protocol and radiation type are correctly selected for profile analysis. Selecting a wrong protocol may lead to wrong results.

WARNING: DATA INTERPOLATION

The interpolation in some algorithms may generate artifacts. Only the experienced users should carry out the data analysis.

IMPORTANT NOTICE: INFLECTION POINT (50%)

As mentioned by Fogliata^1 "The location of this point is proximal to the 50% for standard beams normalized to the central axis, and is at the highest gradient, that could be of the order of 10%/mm. This means that the position of the inflection point can be accurately determined only with very fine measurement stepping. A common step length used for measurements in the penumbra region is one millimeter. With such precision, together with the detector size and type in a high gradient region, the dose level that is then used for profile normalizationcould be affected easily by a 10% error."

 

Profile Analysis

• Click the Profiles tab (1).
• Select the profile(s) (2) to be displayed. The parameters of the displayed profiles are shown in the result table below (3).
• Or place the computer cursor on the profile cursor (make sure that the button (4) is de-selected)
  and press the right mouse and drag it to the desired position. The signal reading is shown in the table on the right (5).

myQA FastTrack workspace – Profiles tab page (example)

Note: The profiles are displayed with linear interpolation.

^1: Fogliata, A., et al. "Definition of parameters for quality assurance of flattening filter free (FFF) photon          beams in radiation therapy." Medical physics 39.10 (2012): 6455-6464.

 

Energy Verification

• Click the Energy tab (1).
• Place the computer cursor on the profile cursor (make sure the button (2) is de-selected). Click the right mouse and drag it to the desired position. The signal reading is shown in the table on the right (3).

myQA FastTrack workspace – Energy tab page (example)

Note: Energy verification is not supported with myQA SRS

 

Startup Behavior

• Click the Startup tab (1).
• Place the computer cursor on the profile cursor (make sure the button (2) is de-selected). Press the right mouse and drag it to the desired position. The signal reading is shown in the table on the right (3).

myQA FastTrack workspace – Startup tab page (example)

 

Profile Analysis Results

Profile Analysis Protocol

The analysis is done according to the protocol selected from a list of available analysis protocols in the Profile ribbon. Protocols will be pre-defined. If the protocol is changed, the profile analysis is automatically updated.

If it is not possible to determine whether the frame was measured for electrons or photons, the photons
protocol will be used.

 

IMPORTANT NOTICE: COMPARE PROFILES WITH THE SAME UNIT

Only the comparison of profiles with the same unit is valid!

WARNING: COMPARE UNDER THE SAME CONDITIONS

Ensure that the profiles are measured with the same measurement setup conditions,
e.g., SSD, buildup, etc. when comparing analyzed profile parameters.

CAUTION: USE SMALL FIELDS PROTOCOL FOR FIELD SIZES < 5 × 5 CM

For profile constancy tests with field sizes < 5 × 5 cm, the Small Fields protocol has to be used.

The use of a standard protocol, which is not specifically defined for small fields, may lead to erroneous QA results.

CAUTION: DOSE RATE CALIBRATION NOT APPLIED

For the myQA SRS device, dose rate calibration is not applied. Ensure you use the same dose rate for subsequent measurements.

 

Results

Analysis results of the extracted profiles are listed in a table with some parameters/properties of a profile.

When comparing the analyzed profile parameters, ensure the profiles are measured with the same
measurement setup conditions (e.g., SSD, build up)

Profile Analysis table (example)

The parameters displayed in the Profile Analysis table are defined in selected protocol. See Chapter 7 in
myQA Platform Reference Guide for algorithms of the parameter calculation.

 

Filter to display selection

Each item has a filter for display selection. Clicking the filter icon will open the Filter dialogue. Only the Name filter uses the free-text fields, i.e., part of the name can be also used for filtering. The rest of the filters use the options of the parameter for filtering, i.e., the full names of an option are used for filtering:

The FW (field Width) filter                                   The Direction filter

 

Profile resampling for the Dolphin

In a Dolphin detector, the chambers are less dense in the outer area than in the center area and thus the chamber distributions in the profile paths are not even. In order to present an even data distribution profile, resampling is applied between two chambers that have greater distance by bilinear interpolation. An Info tooltip next to the name of the detector in the Profile Analysis table describes this information.

WARNING: BILINEAR INTERPOLATION

For the Dolphin, resampling is applied between two chambers that have greater
distance by bilinear interpolation.

 

About FFF beam analysis

In the current software version, the analysis method for the penumbra calculation for FFF beams (see
Section 4.2.3.7 myQA Accept Instructions for Use) is sensitive to the correctness of device positioning. In addition, to ensure correct results, the field size is limited to 20 cm × 20 cm.

It is recommended to use any of the optimized analysis methods for analyzing the profiles of FFF beams,
i.e., FFF or SFPM_35_2019_FFF analysis methods. A warning sign appears next to the name of the analysis
method if a non-FFF analysis method is chosen for a FFF frame. Users should be cautious about results.

 

CAUTION: ANALYSIS METHODS FOR FFF BEAMS

For profile constancy tests, protocols specifically defined for FFF beams are not optimized for FF.

Such application may lead to erroneous QA results

CAUTION: ANALYSIS METHODS FOR FF BEAMS

For profile constancy tests, protocols specifically defined for FF beams are not optimized for FFF.

Such application may lead to erroneous QA results

IMPORTANT NOTICE: SLOPE VALUES FOR FIELDS SIZES < 10 CM × 10 CM FOR SFPM_35_2019_FFF PROTOCOL

Slope values for field sizes smaller than 10 cm × 10 cm for SFPM_35_2019_FFF protocol are rather inconsistent, as the small fields lies in the broad profile peak that is rather homogeneous^2

 

About Small Fields

Standard protocols are defined for standard field sizes. For smaller field sizes, i.e., field sizes smaller than 5 cm × 5 cm, please refer to Small Fields protocol.

Note: Based on the recommendation of the TRS 483, for small fields (nominally smaller than 5 cm × 5 cm),            the field size is calculated as the FWHM of the profile at the 50% of the Dmax.

 

^2: Fogliata, A., et al. "Definition of parameters for quality assurance of flattening filter free (FFF) photon          beams in radiation therapy." Medical physics 39.10 (2012): 6455-6464.