Skip to main content
Deutsch 简体中文

DOSE-X - Measurement

  • Updated

General Measurement Procedure

A typical use case can be described as follows (depending on the particular installation, some of the steps may be skipped):

  • Take the DOSE-X out of storage.
  • Connect mains power cable, detector cable.
  • Turn on the DOSE-X and wait for warm-up of the device.
  • On the Main screen:
    • select a detector from the detector library. If no detector has been configured, see Section 3.6
    • set all applicable corrections
    • set Measurement Type to Dose
    • set Sensitivity to High
    • turn on the Bias Voltage
  • Pre-irradiate the detector.
  • Perform a background (zero) measurement.
  • Start a measurement.
  • Irradiate the detector.
  • Stop the measurement.
  • Write down the measurement value shown on the Main screen, or export the measurement history.
  • When all measurements have been completed, turn off the device, remove cables, bring the DOSE-X back into storage.

 

Device Warm-up

In order to achieve the stated measurement performance, it is necessary for the DOSE-X to warm-up and
perform self-tests after it is powered on; the self-tests run automatically after starting the device.

The warm-up time can vary depending on the environmental conditions of the location of the device

  • 10 minutes after powering the device, provided that:
    • The device has been kept under the required operating conditions (see Section 7.8)
    • The temperature and humidity where it was kept does not differ by more than ± 2°C and ± 2% relative humidity from the conditions at the measurement location.
  • 1 minute after powering the device, provided that it was already sufficiently acclimatized to the conditions at the measurement location and the power was interrupted only for maximum 5 minutes.
  • In all other cases, the warm-up time may be longer than indicated above:
    • It is recommended to verify with a series of background measurements whether the electrometer is sufficiently stable.
    • If moisture has developed on the device as a result of temperature and / or humidity changes, please do not power the device until it is completely dry. See Section 7.8 for more information.

Please note, a measurement cannot be started until the device is fully warmed up.

Power-on Selftests

  • During warm-up the Power-on Selftests running notification (1) is shown.
    Just above the START button, the screen will show how long the selftests have been running (2).
  • A pop-up will appear informing the user that the Power-on Selftests have finished. Tap OK.

Note:  The power button's change of color from red to green indicates the completion of the Poweron                     Selftests, but is not related to warm-up times. The Power-on Selftests completed pop-up must appear             before measurements can start.

 

Setup for Measurements

To prepare the DOSE-X for measurements, select or enter the correct factors for the following. Please note, if performing a charge measurement, certain detector settings cannot be selected / edited and will be greyed out.

  • Detector: select a detector from the dropdown list.
    CAUTION: CHECK THE DETECTOR TYPE AND SERIAL NUMBER
    Ensure that the detector selected from the library is identical to the one which is physically connected to the DOSE-X. Double-check detector type and serial number.
  • Machine: select a machine from the dropdown list.
  • Ionization (k_S): if k_S correction factors have been configured, and should be applied, select the applicable Dose rate (k_S) factor from the Ionization (k_S) menu.
  • Energy (k_Q): if Energy (k_Q) correction factors have been configured, and should be applied, select the applicable k_S factor from the k_Q menu.
  • Temperature, Pressure (k_Tp): To apply k_Tp correction, configure temperature and pressure in the Temperature, Pressure k_Tp menu. The correction factor can be turned ON/OFF.
    Note: To confirm turning the correciton factor ON/OFF, tap the Enter button.
  • Polarity Correction (k_pol) and User Correction (k_user):
    • Activate (or deactivate) application of a Polarity correction (kpol) in the Polarity (kpol) menu, the default is configured in the detector settings.
    • Activate (or deactivate) application of a user-specific additional correction (k_user) in the User Corr (k_user) menu, the default is configured in the detector settings.
  • Bias Voltage: tap the Bias Voltage field to turn ON/OFF the High Voltage, change the Bias value, and select Floated or Grounded. See Floated vs. Grounded Input for clarification on input.
    Note: When turning the Bias Voltage ON/OFF or selecting Floated/Grounded, tap the Enter button             to confirm the action.
  • Sensitivity: select High, Medium, Low, or Auto from the dropdown list. See Chapter 5 for sensitivity range.
    Note: For best performance, select the lowest range possible for the intended measurement while
             avoiding the saturation of the electrometer. Please see the respective detector manuals to
             determine the appropriate ranges and senitivities.
    If Auto is selected, the Automatic Range Detection dialog will open to determine the best sensitivity range for the selected detector and parameters.
  • Measurement Type: select between Dose or Charge.
    To perform a purely electrical measurement (charge and current), select Charge from the menu. In this measurement mode, dose calibration and correction factors will be applied, and the display will be in electrical units.
  • Mode: select the type of Measurement mode: Manual, Trigger, or Timer.
    • Manual mode: the measurement can be started / stopped manually by pressing the START/STOP button.
    • Trigger mode: the measurement is activated / deactivated by pressing the START/STOP button. Please see Trigger mode settings for additional information.
    • Timer mode: the measurement will run for the selected amount of time. See Timer mode for more information.

 

Trigger mode settings

Before activating Trigger mode, the user will need to:

  • Define the value for the high, medium, and low ranges. See Chapter 5 for sensitivity range.
  • Ensure that the Beam on / off times and Pre / post trigger times have been defined in the Trigger Mode settings.
    • Beam on / off times: To avoid spurious starts and stops of measurements, it is required that the
      signal stays above for at least 1 s, or below the threshold for at least 2 s.
    • Pre / post trigger time: To not loose any charge in the event of a slowly increasing signal, the charge collection time is artificially extended by at least 500 ms before the measured current has exceeded, and by at least 500 ms after the current has fallen below the threshold.

After activating Trigger mode, the measurement will automatically start once the measured current has
exceeded the Beam on Threshold value, and the measurement will end once the current falls below the
threshold value.

The Beam on Threshold value can be found in the Background Settings page (see Section 4.4). See
Chapter 5 for information on how the Beam on Threshold is determined.

 

Comment

On the main screen tap Comment to open the comment dialog. Here the user can enter comments for the specific measurement.

Tap Return to close the comment dialog.

 

Connect a Detector

When connecting a detector, it is recommended to first select the detector from the detector library in the DOSE-X. If using a new detector, please add it before continuing with the connection procedure (see Section 3.6.1).

Note: Never connect or disconnect a chamber cable or adapter cable to or from the DOSE-X unless the Bias           Voltage is switched OFF (or set to 0 V).

  • Carefully remove the detector from its carrying case. Do not touch the sensitive area of the detector and ensure the dust cap is on the connector when the detector is not in use.
  • Position the detector in the desired measurement geometry. Use alginment markings on the detector to ensure consistent orientation between measurements.
    Please note that if you are working with a linear accelerator, any uncertainties in the alignment and
    position of the mechanical components can influence the detector alignment and have an impact on subsequent measurements; it is strongly recommended to verify the leveling and alignment of the detector to the reference coordinate system.
  • Ensure that the Bias Voltage at the electrometer is switched OFF (or set to 0 V).
  • Remove dust cap from detector cable and connect an extension cable. It is advised to close the
    protection caps by screwing them together.
  • Ensure the extension cable is in good condition and confirm any induced triboelectric effects (common in a recently unwound cable) have dissipated before taking measurements. Secure the cable so that no sharp bends can be created in it, especially if the detector will be moving.
  • Remove dust cap from the connector and connect it to the extension cable, being careful not to touch either connectors internal components. It is advised to close the protection caps by screwing them together.
  • Turn ON the Bias Voltage, set it to the desired value, and check the device system before proceeding, see Section 3.2.1.

 

Background

The BACKGROUND button shows the time of the last background measurement. Please note, before
performing a measurement, it is recommended to perform a background measurement.

  • Ensure that radiation is switched off before the background is measured.
  • Click RESET to return measurement values to zero.
  • Tap the BACKGROUND button to take a new background measurement.
  • When the background has been applied the button is activated and shows Checked at (time of day).

To open the background settings page:

  • Press and hold the BACKGROUND button.
  • Type in the desired measurement time and tap ENTER (default value is 60 s).
  • Turn on/off the Background Subtraction.
    Please note, when background subtraction is active (ON), the BACKGROUND button will be activated (white text), if the background is not subtracted (OFF), the button will be shown inactive (grey text).
  • View the Beam on Threshold (see Trigger mode settings for more information).
  • Tap the icon to exit to return to the main screen.

 

Start a Measurement

There are three Modes available for starting a measurement:

  • Manual
  • Trigger
  • Timer

See below for information on taking measurements with each mode type.

The finished measurement is displayed on the main screen. See Section 4.6 for more information on
understanding measurements.

Completed measurements will be added to the Measurement History (see Section 4.7).

 

Manual mode

  • Select Manual under Mode.
  • Tap the START button.
  • The DOSE-X begins the mesaurement.
  • Tap the STOP button when the measurment is complete.

 

Trigger mode

  • Check that the Trigger Mode parameters have been set to the correct values. See Trigger mode
    settings.
  • Select Trigger under Mode.
  • Tap the START button. This activates Trigger mode.
  • When the input signal is above the Beam On Threshold for longer than Beam On Time duration, the DOSE-X will recognize the beam on point and start the integration of charge/dose measurement.
  • The DOSE-X will continue to take measurements in the defined beam on/off interval.
  • Tap the STOP button when the measurement is complete.

 

Timer mode

  • Select the desired measurement time via the dropdown menu:
    • 1, 2, 3, 5, 10, or 30 seconds
    • 1, 1.5, 2, 3, 5, 10, 15, 30, or 60 minutes
  • Select Timer under Mode.
  • Tap the START button.
  • The DOSE-X begins the mesaurement.
  • The measurement will run for the selected time.
  • The finished measurement is displayed on the main screen. See Section 4.6 for more information on
  • understanding measurements.

When the measurement is complete it will appear in the Measurement History (see Section 4.7)

 

Reset

  • Tap the Reset button to clear the previous measurement.
  • Tap and hold the Reset button to select Auto or Manual reset.