Users Manual Part 2

Clinical User’s Guide IBA | 12-9|
Volume 1 - Treatment Session
|Part II - Using Treatment Room Equipment Alignment Tools and Devices |
Working With Laser Devices
Laser devices may be used to align the patient on the couch.
Note: Use the lasers for initial positioning of the patient, use the X-ray tubes next.
Lasers have a precision of ~3 mm; the precision of the X-ray based method: is
<1 mm.
Location of Lasers in a GTR
Laser Locations for PBS Dedicated Nozzle
Nine lasers are located in the Gantry Treatment Room (GTR):
 Laser 1 (mounted on the nozzle edge) emits a vertical laser beam.
 Laser 2 (mounted on the nozzle edge) emits a vertical laser beam.
 Laser 3 (mounted on the patient enclosure, opposite the nozzle) emits a
crosshair laser beam.
 Laser 4 (mounted on the ceiling, above the PPS) emits a vertical laser plane
containing the gantry rotation axis.
 Laser 5 (mounted against the wall opposite the gantry) emits a horizontal laser
plane containing the gantry rotation axis.
 Laser 6 (mounted on a column or wall bracket, to the left of the PPS when facing
the gantry) emits a crosshair laser beam.
 Laser 7 (mounted on a column or wall bracket, to the right of the PPS when
facing the gantry) emits a crosshair laser beam.
CAUTION The nozzle lasers have been calibrated at 270° only. Lasers therefore
should be used for rough alignment only.
Important As radiation therapy technologist (RTT), pre-position the patient using
the lasers. During this process, pay attention to the potential large
difference between the position of the isocenter as indicated by the
lasers and the position of the isocenter as indicated by the X-ray image
guidance system. A large difference would indicate that one of these
systems needs to be re-aligned.