Zeiss INTRABEAM, Instructions For Use Manual

Page: 35 / 82

Version 6.2
G-30-1767-en
Page 35
INTRABEAM Water Phantom Operation
Positioning the probe tip for recording the depth dose curve
Exact positioning of the probe tip is a precondition for accurate and mean-
ingful measuring results.
Providing illumination through the water tank from the rear facilitates detec-
tion of the light gap between the probe tip and the measuring chamber.
In order to record the depth dose curve, the IC ionization chamber must be
seated in the measuring chamber for the depth dose measurement.
Positioning the probe tip in the X and Y axis
The aim of the positioning is to position the probe tip as exactly as possible so
that it is positioned centered on the measuring window of the IC ionization
chamber and touches the housing of the measuring chamber for the depth
dose measurement .
"Touching" here means that, although the probe tip does in fact contact the
measuring chamber, it nevertheless exerts practically no pressure at all.
The ionization chamber holder fixes the IC ionization chamber in the front,
flattened portion of the measuring chamber so that the measuring window of
the IC ionization chamber is always located exactly in the center and the ver-
tical distance (in the Z axis) from the measuring chamber wall always remains
the same.
Since the rotary feedthrough allows for only a small adjustment path in the X
and Y axes. the XRS 4 is already relatively well centered on insertion.
Positioning in the X and Y axes is performed using an adjusting knob. One full
turn of the adjusting knob corresponds to a travel path of 1 mm. The scale
graduation is 10
μ
m.
Positioning in the Z axis is performed using an adjusting knob with a display.
The highest point on the display is the zero position. The display shows the
travel path in 1 mm steps with 2 decimal places.
• Loosen the locking screws on the adjusting knobs for the X and Y axes.
Release the locking lever on the adjusting knob for the Z axis.
• Actuate the adjusting knobs only when the corresponding locking screw
has been loosened or the corresponding locking lever has been released.
• Always observe the probe tip when performing adjustments on the posi-
tioning unit.
NOTE If the water phantom is set up in an insufficiently illuminated environment,
the positioning of the probe tip is difficult to recognize. This can cause posi-
tioning errors.
•
Provide sufficient illumination.