Users Manual Part 7

IBA | H-12 | Clinical User’s Guide
Volume 1 - Treatment Session
Glossary of Terms
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Multipactor Effect
As soon as an RF field is in the RF cavity, some electrons are pulled free from the
surfaces of the cavity and are accelerated by the field. If these electrons are
accelerated to approximately 100 electron volts and impact another surface of the RF
cavity, depending on the secondary electron emission coefficient, they may produce
one or more secondary electrons. The RF field may then accelerate those secondary
electrons when the polarity of the field changes. This may lead to a positive feedback
effect if certain conditions of RF field frequency and the distance between surfaces
of the RF cavity are appropriate. If this happens, the electrons bouncing back and
forth between the facing surfaces of the RF cavity may carry a current strong enough
to prevent the RF from achieving its nominal value. This phenomenon is known as
the multipactor effect. Its electrical consequence is a short circuit.
Nozzle
A group of subsystems located between the exit of the Gantry Beam Transport
System and the Patient. The Treatment Control System (TRCS) interfaces with the
nozzle, via the PMS, to direct the beam at the treatment area and control the
irradiation. See also: Gantry, Gantry Beam Transport System, Treatment Control
System.
Ohm
A unit which measures the resistance to electric current flow. In the meter-kilogram-
second system, a resistance (R) of 1 ohm produces a 1 ampere (A) flow of current in
a wire with a potential drop of 1 volt (V). The formula governing flow of current in a
resistor is known as Ohm’s law: V = I * R.
Oil Diffusion Pump
A type of vacuum pump used on the accelerator (cyclotron). See also: Adsorbtion.
Original Equipment Manufacturer (OEM)
Describes the equipment manufacturer rather than the equipment supplier.
Patient Positioning Verification System (PPVS)
The PPVS comprises hardware and software (e.g., adaPTinsight) to ensure the
proper positioning and alignment of the tumor to be treated by the beam.
Patient Positioning Device (PPD)
The PPS, gantry, PBS Dedicated snout. See also: Nozzle, Gantry, Patient Positioning
System.
Patient Positioning System (PPS)
The six axes mechanical structure that supports and positions the patient. The
Treatment Control System (TRCS) interfaces with the PPS, via the PMS, to accurately
position the patient. See also: Treatment Control System.