  At the Centre for Proton Therapy at the Paul Scherrer Institute cancer
patients are treated with a fixed beamline and in two gantries for ocular and
non-ocular malignancies, respectively. For the installation of a third gantry a
new patient safety system (PaSS) was developed and is sequentially being rolled
out to update the existing areas. The aim of PaSS is to interrupt the treatment
whenever any sub-system detects a hazardous condition. To ensure correct
treatment delivery, this system needs to be thoroughly tested as part of the
regular quality assurance (QA) protocols as well as after any upgrade. In the
legacy safety systems, unit testing required an extensive use of resources: two
weeks of work per area in the laboratory in addition to QA beam time. In order
to significantly reduce the time, an automated PaSS test stand for unit testing
was developed based on a PXI chassis with virtually unlimited IOs that are
synchronously stimulated or sampled at 1 MHz. It can emulate the rest of the
facility using adapters to connect each type of interface. With it PaSS can be
tested under arbitrary conditions. A VHDL-based formal language was developed
to describe stimuli, expected behaviour and specific measurements, interpreted
by a LabView runtime environment. This article describes the tools and
methodology being applied for unit testing and QA release tests for the new
PaSS. It shows how automation and formalization made possible an increase in
test coverage while significantly cutting down the laboratory testing time and
facility's beam usage.
