Users Manual Part 6

Clinical User’s Guide IBA | 46-9|
Volume 1 - Treatment Session
|Part XI - Patient Positioning and Alignment Introducing Patient Positioning and Alignment |
Taring the PPS
What is the tare, and why should it be done?
The PPS Leoni is equipped with a force torque sensor, which allows measuring the
mass of the payload (couch, patient) carried by the robot. This measure of payload
feeds the algorithms ensuring the high accuracy of the PPS.
As for any weighing machine, a PPS taring procedure (as explained in section
Procedure to perform the tare below) must be done, in order to define a correct zero
reference of the mass measured by the PPS. This procedure is quick and easy to
perform, but has to be done carefully after the validation of some prerequisites.
When the tare must be done?
 After each new startup of the PPSCU.
 When the PMS software or hand-pendant request it (every 20 hours).
Prerequisites for performing a tare
 The couch is installed on the PPS.
 The couch insert (i.e. couch extension) is attached to the couch base.
 The couch is horizontal (pitch = roll = zero).
 No mass is installed on the couch.
 The couch is recognized by the system.
 No external force is applied on the couch during the tare.
 The PPS is at a standstill during the tare.
WARNING Remove all loads from the couch before taring.
Important Take care to check that all the prerequisites are met before performing
a tare. Otherwise the tare is not valid, and the accuracy of the PPS will
be deteriorated, possibly resulting into incorrect treatment of the
patient.