Users Manual Part 6
Clinical User’s Guide
IBA | A-7 |
Volume 1 - Treatment Session
Nozzle Types and Components
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PBS Dedicated Quadrupole Magnets
Purpose of the PBS dedicated quadrupole magnets is to focus the beam at isocenter
so that the size of the beam remains limited. These quadrupole magnets are made
of laminated steel to enable a fast current change without overheating the structure
of the quadrupole magnets.
Scanning Magnets
The two scanning magnets located in the nozzle deflect the beam and continuously
paint the treatment field with a relatively wide beam area. The upstream magnet
scans the beam in the Y direction at 30 Hz; the downstream scanning magnet scans
in the X direction at 3 Hz, all expressed in the nozzle coordinate system.
PBS Dedicated Nozzle Pre-assembly
The PBS Dedicated Nozzle Pre-assembly is primarily a vacuum chamber that houses
the retractable X-ray tube and onto which the range shifter and ridge filter are
mounted.
Retractable X-ray Tube
Aligning the patient for treatment is accomplished with the use of two X-ray (XR)
tubes. One of the X-ray tubes is located inside the nozzle. It can be pneumatically
rotated into or out of the beam path without interrupting the vacuum.
Range Verifier
The Range Verifier (RV) is located downstream of the PBS nozzle dedicated pre-
assembly. The range verifier is only used to detect discrepancies in beam range to
protect the patient from large errors in range setting.
The range verifier includes 9 tugsten/copper plates insulated from each other by a
thin kapton film. The plates and insulators are stacked together and located
perpendicular to the beam axis. When the range verifier is placed in the beam path,
the beam stops in the stack of plates, at a specific depth determined by the energy
of the protons. The current collected in each plate is measured, thereby making it
possible to determine the range of the beam.
Beam Stop Assembly
The beam stop is a copper block that can pneumatically be moved into the beam path
to block the beam.