Users Manual Part 6

Clinical User’s Guide
IBA | A-3 |
Volume 1 - Treatment Session
Nozzle Types and Components
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Nozzle Types and Components PBS Dedicated
Nozzle Structure
The PBS Dedicated Nozzle is specifically designed for delivering beam in the Pencil
Beam Scanning (PBS) treatment mode.
To identify the major components, refer to Figure A-1.
Ionization Chamber 1 (IC1) (or Low Pressure Ionization Chamber 1 - LPIC1):
to check the alignment of beam at the nozzle entrance.
PBS Dedicated Quadrupole Magnets: a set of two quadrupole magnets that
focus the beam at isocenter.
Scanning Magnets: to bend the beam in order to send it at the prescribed
position according to the location requested by the Treatment Planning System
(TPS). One magnet bends the beam horizontally, the other vertically.
Retractable X-ray Tube: the X-ray tube is inserted in the beam line to take Beam
Eye View (BEV) X-ray pictures; the X-ray tube is retracted from the beam line
during proton beam irradiation. This X-ray tube is located in the PBS dedicated
nozzle pre-assembly, which is under vacuum.
Ionization Chambers 2&3 (IC2/3): to monitor beam characteristics (such as
flatness, beam position, beam size, etc.) and the dose just before the beam
leaves the nozzle.
Snout Holder: to be able to move the accessory drawer towards or away from
the isocenter.
Accessory Drawer: at the end of the PBS dedicated nozzle an accessory
drawer caters to an optional range shifter ridge filter, or snout. This accessory
drawer can be put in or out of the beam path depending on whether or not an
accessory or snout is used in the prescription. Possible accessories:
Range Shifter: consists of different sets of blocks of different thickness; it is
used to treat very shallow targets and have full modulation to the skin.
Ridge Filter: an accessory that reduces the number of layers required for
the small range by enlarging the width of the Bragg peak. The value of the
enlargement is a functions of the ridge filter design.
PBS Dedicated Snout: optionally, the snout can be inserted into the
accessory drawer. The snout can hold a maximum of two accessories.
The Scanning Controller
Particle therapy uses positively charged particles of varying energies (i.e., varying
speeds) to irradiate tumors inside a patient's body. In the PBS beam delivery
technique, a narrow particle beam is deflected in two perpendicular directions, both
orthogonal to the beam axis, in order to scan the beam. These deflections are