Click on the Measurement button, in the Tasks navigation pane to display the Measurement page.
The Measurement page contains the graphical windows to show the measured data in different views:
- 0D Data View.
- 1D Data View.
- 2D Projection View.
- 3D Data View.
- 3D Device View.
For an Absolute Point measurement, only the numerical measurement results are displayed in0D Data View.
The descriptions of these views and their context menus are provided in Section 5.1 to Section 5.5, myQA Accept Reference Guide.
Measurement page - 1D data view
By default, the 1D Data View is displayed in the content area and the other three views are listed on the
right side.
- Double click to a desired view in the list to display it in the content area.
- To modify the view size, move the mouse over the border line between the different views, and hold the left mouse button and move the border line to the desired position.
Controller
Assuming your queues have been defined, the equipment is switched on, connected to the PC and setup under the accelerator according to the recommendations (isocenter as well as water surface already stored). The next step is now to connect the CCU controller to the software.
Click to the Controller tab on the bottom of the Content area to display the Controller view.
The Controller view has a button bar on the left side, representing the recommended workflow beginning
with connecting the electrometer to the software and ending with the normalization. There are also three
tabs, the Controller panel, Electrometer panel and Positioning panel, giving you full control about
positioning and electrometer settings. Finally, in the lower part you find information about the controller,
detectors and environmental conditions.
Measurement – Controller View
Connection and Setup Workflow
Connection
After the CCU controller is switched on and physically connected to the computer, you will get the following display in the Controller view.
On the left side of the panel you can see a button bar, following the workflow from connection over High
voltage setup to Normalization.
Press the Connect button (1) to establish the connection between the CCU and the software.
After connection has been established successfully, the button changes (2).
Gantry Coordinates
Assuming the Phantom has been set up correctly and water surface as well as Isocenter has already been
stored using the remote control, the Gantry coord. button will be shown with a green checkmark now.
If this is not the case, press the Positioning panel tab and set the Isocenter as well as the Water surface
selecting the Set position drop down. Press there the “Isocenter” and “Water surface” button to define
these positions. Now the Gantry coord. button changes from red to green.
Set position
HV Setup
Pressing this button, the High Voltage will be switched on and set to the predefined voltage of the
selected detector (previously entered under Common settings / Equipment setup / Detectors). In case of
semiconductor detectors, the predefined High Voltage is 0 and therefore set to 0 as well.
You may change the High Voltage any time.
CAUTION: HIGH VOLTAGE
Ensure that the correct High Voltage has been selected. Incorrect High Voltage can lead to false measurement results. In case of diodes connected to High Voltage, the probe can be damaged. Diodes only must be connected to HV = 0.
After the High Voltage has been set, the HV Setup button will be shown with a green checkmark.
Background
Now press the Background button to measure the background with the accelerator switched off. In the
Electrometer panel part under the General tab, enter the background measurement time. Default is 10
seconds.
Measurement - Background
The Background button will be shown with a green checkmark after the background has been measured
successfully.
Normalization
Finally, Normalization has to be performed. Usually this is done with the detector placed in the central
beam in Dmax depth. Switch on the accelerator and then press the Normalization button. In the
Electrometer panel part under General, you can enter a percentage to which the measurement will be
normalized. Default is 100%.
Measurement - Normalization
The Normalization button will be shown with a green checkmark after Normalization has been performed
successfully.
Now all settings have been completed, all buttons are shown with a green checkmark, you are ready for
measurement.
Start Measurement
After all necessary pre-conditions for the measurements have been fulfilled, a measurement can be
performed. For the measurement, you need to have the Queue panel open as the central control window. If not already open, press the Queue button to open the panel.
Following screen appears with Queue panel and Controller panel open.
Measurement window
Since the Start button in the Queue panel is still grayed out, just check either all queue items in the panel or single queues to be measured.
Now the Start button is enabled and measurements can be performed.
Measurement - Start
Switch on the Accelerator and press the Start button. The button bar switches to the status shown below:
Measurement – Pause / Stop
Pressing the Pause button during measurement, the movement pauses at current position. You can continue at the current position by pressing the Star button once more.
When pressing the Stop button, the current measurement will be stopped. Pressing the Start button will repeat the measurement once more.
Measuring through the queue items, the status indicators will be displayed according to the measurement progress.
In the case below, all queue items are valid. The first one has been measured already and the second one is paused due to required change of field size at the accelerator. You will be prompted by the software to change the field size. After changing the field size, just press OK in the message window and the measurement continues automatically.
Measurement – status indicators
After all profiles measurements have been finished, a balloon message appears,
and a window like the one shown below is displayed, containing the measurements. Sometimes you may
have different measurements in different projects, and then you can easily switch between the windows by selecting the corresponding tabs below the measurement window.
Profile Measurement – performed measurements
Beam Detection
Beam Detection is a function to check whether the beam is on or off. This function is described in Section
3.2.1, myQA Accept Reference Guide.
If the beam is not on when the Start button is pressed the measurement will not start, or during the measurement the beam is off, the measurement will stop. In both cases a message about the beam status
appears.
Turn on the beam, the measurement will automatically start or continue.
Saving Data
After performing measurements you can store them by selecting Save As… in the File menu.
A standard File Save window appears where you select the destination folder, name and the file format. The Save button finally saves your project. See Section 3.2 for the formats can be saved with myQA Accept.
Measurement - Saving data
IMPORTANT NOTICE: BACK-UP DATA
Please make sure to back-up data files and queues on a save place (e.g., server).
IMPORTANT NOTICE STORING RAW DATA BEFORE DOING MODIFICATIONS
Always store the curves directly after measurement. Only after storing the original curves, it is recommended to modify them. This prevents you from losing the original data.
Helpful Hints for Measurements
Small Field Measurements
For big fields, it is recommended to use the continuous mode to save time. This is a considerable advantage of the measurement system consisted of Blue Phantom family and myQA Accept software.
However, for fields smaller than 5 cm × 5 cm, it is recommended to switch to the Step by Step mode due to the following challenge:
- The reference detector may disturb the field measurement (possible shadow).
- Use of chambers with small volume for better point resolution.
To avoid the possible shadow of the reference detector, measure with a Stealth chamber as reference or without a reference chamber. To eliminate the LINAC pulses without reference detector, increase the time per measurement point to a value between 0.5 and 1 second.
The above measures also overcome the second challenge, i.e., using chambers with a small volume. Since
the chamber sensitivity is proportional to the volume, the electrometer has to amplify the signal, and the
same time also noise, greatly.
Large Field Measurements
For large field measurements, e.g., 400 mm × 400 mm at more than 20 cm water depth, it is necessary to create diagonal queues or half-profiles, due to the physical limits of the phantom.
For exact phantom setup, please refer to the corresponding phantom user manual.
Diagonals with Collimator at 45º
One common method is to rotate the Collimator by 45º degrees and define a diagonal measurement. Therefore, enter under the diagonal scan definition in the Extended settings a Collimator Angle of 45º
degrees and choose to scan with maximum possible field size.
Half Profile Measurement
In some cases, it is necessary to perform measurements in very large fields, or in areas that are out of the physical limits of the phantom if it is placed centrally according to the LINAC crosshairs. In these cases, the scan must be performed in two steps, and the scans will afterwards be joined into one curve. Therefore, you need to have two selected and overlapping (in CAX) half profiles of the same type and with same parameters. The command used to join the two half profiles can be found under menu Data Handling > Mathematics > Join.
Depth Dose Measurements
Due to the water surface tension effect it is recommended to measure the depth dose always beginning from the depth towards the water surface. When measuring from the water surface into the depth, the scan may not be measured correctly.