Users Manual Part 7

Clinical User’s Guide IBA | H-13|
Volume 1 - Treatment Session
Glossary of Terms |
Peak Current
The maximum current that flows during a complete cycle.
Peak-reverse Voltage
The peak ac voltage that a rectifier tube will withstand in the reverse direction.
Peak Voltage
The maximum value present in a varying or alternating voltage. This may be positive
or negative.
Penning Gauge
A type of vacuum gauge used within the PTS. See also: Pirani gauge.
Permanent Magnet Quadrupole (PMQ)
A quadrupole magnet located downstream of the gradient corrector, which steers
the beam toward the degrader. See also: Trim Coil.
Pitch and Roll (P/R)
Two of the six axes on the PPS. See also: Patient Positioning System.
Pirani Gauge
A type of vacuum gauge used within the PTS. See also: Penning gauge.
Plasma
A plasma is an ionized gas. A state of matter characterized by unbound negative
electrons and positive ions that may conduct electrical current. In a plasma, the
electrons have been stripped away from the central nucleus. Therefore, a plasma
consists of a sea of ions and electrons, is a very good conductor of electricity, and is
affected by magnetic fields. Plasma is often called the “fourth state of matter,” along
with the other states of matter: solids, liquids and gases. Examples of plasma can be
found in lightning, the Aurora borealis, fluorescent and neon-type lighting, arc
welding, and machines built to study nuclear fusion.
Polyvinyl Chloride (PVC)
Material used for a type of water pipe used throughout the PTS.
Positioning Control Unit (PCU)
Located in the gantry pit. Computer system responsible for controlling the moving
devices and systems associated with the Patient Positioning Device. See also:
Patient Positioning Device.