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POSITIONING FOR TREATMENT
5.1.4
Positioning the System for Treatment
Before you Begin
Position the patient so that the isocenter on the overlays is aligned with the Linac isocenter
(projected by wall lasers).
Sometimes the weight of the patient may cause the couch to tilt downwards. This can be
compensated using the tilt adjustment screw on the couchmount (see Page 24). Use a spirit level
to bring the Stereotactic Headring or Stereotactic Mask System into an exact vertical position.
Before every treatment, the lasers must be verified using the Winston-Lutz Test.
Equipment Verification
During preparation, verify that all components are working together correctly by irradiating an x-
ray film during a phantom treatment.
How to Position the Patient for Treatment
Steps
The Stereotactic Target Positioner must be removed prior to the treatment.
Hardware User Guide Rev. 4.9 RT / RS Stereotactic Hardware
1.
Move the treatment couch into the 0° position.
Use the A/P, lateral and vertical translations of the treatment couch for the first isocen-
2.
ter adjustment.
3.
If available, use the couchmount for fine adjustment to the isocenter (see Page 23).
Check that the isocenter printed on the overlays is aligned on all four sides with the
4.
Linac isocenter, as projected by the wall lasers.
Refasten the locks of the couchmount (see Page 25). This prevents further adjustment
5.
using the rotary knobs and provides additional positioning stability.
Set the couch and the gantry to the first treatment position according to your treatment
6.
plan. The isocenter printed within the gray lesion contour should now be correctly
aligned with the laser-projected isocenter.
Use the Linac light field to verify that the printed gray irradiation area matches the light
7.
field.
8.
Remove the target positioner.
Initiate treatment with the first field.
9.
For further treatment fields, mount the target positioner again, and follow steps 5
through 9 as described in this table.
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