The application of myQA Accept for Proton Therapy (PT) includes the measurement and analysis of Bragg
Peak (BP) and Spread-Out Bragg Peak (SOBP)
General procedure for the BP and SOBP measurement and analysis:
- Set up the equipment in Common Settings – Equipment Setup:
- Define a PT Machine
- Select the controller to be used
- Define the field detector and reference detectors
- Select the Analysis protocol in Common Settings – Analysis Parameters - Proton Depth Dose Bragg Peak or Proton Depth DoseSOBP.
- Define the measurement preferences in Common Settings – Measurement Preferences:
- Define the scanning regions
- Define the beam loss detection settings
- Create the measurement queue in the QueueSetup page
- Perform the measurement in the Measurement and analysis in Data page
The detailed procedure is described in the sections below.
Define a PT Machine and Detectors
Note: Please see Section 4.2.1 for the detailed information about the equipment setup.
Create a Machine of Proton Therapy Type
- In Common Settings (1) > Radiation Devices (2), Click New (3).
- In the Radiation Device Setup template, select a machine in the Proton Machine dropdown list (4)
and enter the machine name (5). Select a SAD and maximum field size (6) (for display only). Enter the energies (7) with which a list of energies is created. The created energies will be available in the Energy dropdown list in the Queue Setup page. The value in the Delta Energy box is the energy interval in the energy range of Min Energy and the Max Energy. - Click OK (8). The machine will be saved and appears in the Radiation Devices list (9).
Edit a PT Machine
- Select the machine in the Radiation Devices list (9). Its parameters are displayed.
Radiation Devices list (9)
New: For creating a new radiation device (see Section 10.1.1)
Edit: For editing the radiation type and energy values of the selected radiation device
Delete: For deleting the selected radiation device
Properties of selected Radiation Devices (10)
Type: The energy template will be changed if selecting a different energy type
Source Axis Distance and Maximum Fieldsize Inline / Crossline: The values can be edited. They are for
information only and do not affect measurements and analysis
Radiation Types / Energies (11)
Creating a new radiation type /energy:
- Click New
- Click a blank parameter area (in pink color) and then select the energy type and enter the value for the corresponding parameter.
- Repeat the above step to fill in all require parameters.
Note that the maximum and minimum energies are not editable here and can only be entered when creating a new machine.
Define the Detectors and Controller
- Define the controller: Click Common Settings > Equipment Setup > controllers. Put the controller online. Click to select it.
- Define detectors: Click Common Settings > Equipment Setup > Detectors. Check that both field and reference detectors are in the Installed Detectors list (1) and edit the parameters if necessary. Select the reference detector (2).
BP and SOBP Analysis Protocols
Note: Please see Section 4.2.3 for the detailed information about analysis protocols.
The SW provides the IAEA TR398 protocol for the BP or SOBP analysis. It is selected by default and not
editable.
To access the protocols, click Common Settings > Analysis Parameter > Proton Depth Dose Bragg Peak or Proton Depth Dose SOBP.
Copy and edit analysis protocols
You can create a customized protocol by copying an existing protocol (using the Copy selected button)
and editing the parameters in the Details box or importing your own protocol (using the Import from file button). The selected protocol will be used for analysis.
IAEA TR398 Protocol for Bragg Peak
Bragg peak (R100): Bragg peak position (the depth at the dose maximum)
R50 1: Position where the dose is 50% of the dose maximum at left side of the Bragg peak
R50 2: Position where the dose is 50% of the dose maximum at right side of the Bragg peak
FWHM: Field width at half maximum: the distance between R50 2 and R50 1
R user: Position where the dose has the user-defined percentage relative to the dose maximum (up to 6 positions)
D user: Percentage at user-defined depth value
Distal fall-off: Distance between two user-defined percentages on the right side of the Brag peak. Distal
fall-off is similar to penumbra in profile analysis.
IAEA TR398 Protocol for SOBP
M user: Distance of edges at the user defined percentage relative to the dose maximum value
R user: Position where dose has the user defined percentage relative to the dose maximum (up to 6
positions)
D user: Percentage at user defined depth value
Distal fall-off: Distance between two user defined percentages on the right side of the maximum. Distal
fall-off is similar to penumbra in profile analysis.
BP / SOBP Measurement Preferences
Note: Please see Section 4.2.2 for the detailed information about measurement preferences.
Define Scanning Regions for the Step-by-Step Mode
If the step-by-step scan mode is selected, the regions for different scanning speed needs to be defined
Example: Defining regions for step-by-step scan mode
- Click Common Settings > Measurements Preferences > Scan Region Setup.
- Click the New button (1).
- The measurement parameters are automatically filled in (2). Click the Energy dropdown list and select the desired energy value (only for informative display).
- Entered the actual Bragg Peak position(at the dose maximum) in the DMax Position box (3).
- Use the Add button (4) to add desired regions and define the step in every region (see detailed
instruction in Section 4.2.2.2
Beam Loss Detection for Synchrotron Beams
In synchrotrons, the beam is delivered in spills. The time structure of the beam is shown in the schematics
below.
The operation cycle of synchrotrons can vary from approximately 2.5 to 10 s. A portion of this time is allocated for acceleration and deceleration of the beam.
The spill length and pause between spills depend on the specific machine and the delivery technique used.
A reference chamber (such as Stealth) is required for the beam loss detection. If the reference chamber detects that the beam is on, the data points collected by the field chamber (such as Stingray) will be kept, otherwise discarded.
Define synchrotron beam loss detection
- Click Common Settings > Measurements Preferences > Scan Preferences
- Activate the Pause scan on beam loss and Pause measurements when beam is off boxes.
- Enter the thresholds in Beam on threshold and Beam off threshold. A threshold is a percentage of the normalized maximum value. It is recommended to set Beam on / off threshold to 8% / 12%.
- For Remove number of points after pulse on, it is recommended to set the Amount of points to 1 or 2.
Recommendations for Synchrotron Beam Measurement Settings
- Avoided saturation of both field and reference channels
- Normalization time should be at least one beam cycle (spill + pause). Except if the pause is shorter compared to the spill length
- Beam on / off threshold is recommended to be set to 8% / 12%. If the threshold is set too high and the current does not reach the beam on threshold, the scan may stay in a waiting loop.
See some examples:
| Spill length (s) | Pause (s) | Normalization (s) | Acquisition time(s) |
| 5 | 2 | 10 | 3 - 5 |
| 4 | 1 | 5 | 3.5 |
| 9 | 1 | 5 | 3.5 |
IMPORTANT NOTICE: RESTART MYQA ACCEPT IF CHANGING THE BEAM LOSS DETECTION SETTINS
If the threshold values or beam loss detection parameters are changed, myQA Accept must be restarted.
Create a BP / SOBP Measurement Queue
Note: Please see Section 4.3 for the detailed information for creating measurement queues.
CAUTION: DEFINE ADEQUATE SCANNING SPEED FOR PROTON MEASUREMENTS
For commissioning and QA in a PT environment, it is strongly recommended to either use continuous mode with a maximum speed of 5 mm/s or step-by-step mode to ensure the required measurement accuracy.
Once "Protons" is selected as the Radiation type, a warning tooltip with the above message appears.
Procedure to create step-by-step measurement queue
The procedure is illustrated with an example below:
- Check that the parameters in Queue settings (1) show the correct device and conditions.
- In Queue item settings, select a scan type from the list (2).
- Define the required parameters on the Basic settings tab (3).
- When a PT machine is selected in Queue settings, Radiation Type is automatically set to Proton and the SOBP (4) and Single Spot (5) options becomes available.
- Select the Sbox if a SOBP measurement should be performed.
Enter the modulation and SOBP range in the corresponding box. These two parameters are used for measurements but are not used in the analysis. - Select the Single Spot box if a Single Spot measurement should be performed.
See Section 10.6 for more information on Single Spot and SOBP measurements and analyses.
- Select the Sbox if a SOBP measurement should be performed.
- Select the desired energy value in the Energy dropdown (5) created when creating the PT machine.
Please note, when SOBP has been selected, the Energy dropdown is not available. - In the Scan settings box, select a scan mode and enter the scanning depth (6).
- In the Step by Step settings box, select / enter scan type, scan speed, and the scan region template for point steps (7). See for defining the template of scanning regions.
- Click Add Item to Queue (8).
- Repeat the above step if more queue item should be added.
BP and SOBP Measurement and Analysis
Note: Please see Chapter 5 for the detailed information about performing measurements.
Once the measurement queue and analysis protocol are defined, the measurement is ready to be performed. Once the measurement finishes, analysis will be automatically performed with the protocol selected in the Analysis Parameters page.
Single Bragg Peak measurements
Single Bragg Peak measurements are normally performed with Stingray or large IC (Ionization Chamber) delivering a continuous single spot in the center of the chamber.
Measurement setup example: BP PT phantom with Stingray as the field detector and Stealth as the
reference detector
SOBP measurements
SOBP measurements are normally done using PPC05. Each acquisition point of the entire cube must
be measured one-by-one, which makes the measurement very time-consuming. Therefore, it is not recommended to use myQA Accept for this type of measurements.
Alternatively, measure the SOBP with Zebra and OmniPro Incline (see the corresponding user manual) and then import the measured data into myQA Accept for analysis.
Measurement Procedure
- Make sure the CCU is switched on and network-connected to the PC, and in the Common Settings >Equipment Setup > Controller, this CCU is selected.
- In the Controller panel, click Connect (1).
- The Gantry coord. button should turn green together with the Connect button. If not, check whether the water surface and the isocenter position are saved correctly on the remote control (please refer to Blue Phantom2 or Blue Phantom PT user manuals for instructions).
- Use the remote control to move the detector to the water surface and then save this position as the
water surface in the remote control. Similarly, save the isocenter position. The Gantry coord. button (2) will turn green. - Click HV Setup (3) if the detector requires a high voltage. Wait until the voltage is correct and stable.
- Click Background (4) to acquire the background.
- Turn on the beam. Click Normalization (5). The normalization time is defined in Electrometer panel > General > Norm. Time (5s by default).
- During beam-on, check the responses of the two detector channels. Make sure they are in the green regions, especially not saturated. If necessary, click the Electrometer panel tab and change the sensitivity.
- Click the Start icon in the Queue panel to start the measurement.
- Once the measurement is completed, the measured data is displayed in the Data page and the analysis are list in the Numerical Analysis panel. See an example below.
Importing OmniPro-Incline Measurements
- In the main menu, click File > Open.
- In the Open browser, select OmniPro Incline (*.csv) as the file type, select the file, and click Open.
- If the imported data does not have information about the Bragg Peak type (BP or SOBP), a popup dialog appears. Click Yes if it was a SOBP measurement or No if it was a BP measurement.
- Since the OP-Incline data does not contain the energy information, a dialog pops up. Please fill the
requested parameters and then click OK.The information is only for display and does not affect the analysis. Once the OmniPro-Incline data is imported, the analysis is automatically performed depending on the type of the measurement data (BP or SOBP); whether it was user-defined or imported.
SOBP Modulation: It is the width of the SOBP.
Range: Reference range (middle of the SOBP) or the residual range can be entered here. Once a range is defined, a nominal energy corresponding to this range will be displayed. Note that this value does not affect the analysis, it is information for consideration.
Note that the SOBP option, SOBP Modulation and energy can also be defined / changed in the Data Info dialog of the imported data (see the sub-section below). - Once the data is imported, it is displayed in the Data page and the analysis are list in the Numerical Analysis panel. See an example below.
Setings in the Data Information dialog
For the imported OmniPro-Incline measurements, the setting of the SOBP checkbox determines the kind of analysis (Bragg Peak or SOBP).
- Select a measurement (e.g., 1) and then click the Info button (2) in the toolbar; the Data Information dialog (3) will open. The parameters in the dialog are editable
- Check mark the SOBP checkbox (4), the SOBP analysis protocol will be used for analysis. If this box is unchecked, the Bragg Peak analysis protocol will be used for analysis
Print Templates
- In the main menu bar, click the File menu (1) and then select Print… The Print Preview dialog (2) open. There are 4 print templates available for the PT applications (3).
Note that appropriate print template must be selected to see the measurement and analysis data. If a wrong template is selected, only data is displayed, not the analysis.