Zeiss INTRABEAM, Instructions For Use Manual

Page: 56 / 82

Operation INTRABEAM Water Phantom
Version 6.2
Page 56 G-30-1767-en
Measuring isotropy without spherical applicator
The geometry of the spherical radiation emission of the probe tip is checked
on an XRS 4 when measuring the isotropy. The isotropy check is performed at
maximum beam current and the beam voltage selected for the respective XRS
4.
Positioning the probe tip for isotropy measurement
Exact positioning of the probe tip is a precondition for accurate and mean-
ingful measuring results.
• Insert the IC ionization chamber in the measuring chamber for the isotro-
py measurement.
• Ensure that the measurement setup has been properly prepared and all re-
quired electrical connections have been made.
• Leave the positioning in the X and Y axes previously performed for the
measurement of the depth dose curve unchanged.
• Move the probe tip upwards (in the Z axis) until it is positioned roughly
centered in front of the measuring chamber for the isotropy measure-
ment.
• Ensure that the XRS 4 is properly seated in the XRS mount and that all cov-
ers are properly attached to the water tank.
• Start the radiation generation.
• Set the electrometer to current measurement. A current value appears on
the electrometer display.
• Watch the current reading on the electrometer display and move the
probe tip further upwards. You can see that the current value increases
accordingly.
• If you adjust the probe tip further upwards and the current value drops,
you have passed the exact target point.
• Move the probe tip back down slightly and vary your setting in the Z axis
until you have set the maximum current value.