A major goal of the development of the new Gantry
2 is to provide new scanning features more robust
against the organ motion during irradiation.
A 2D cartesian magnetic scanning (with infinite
source-to-skin distance SSD) will provide the
same basic scanning performance as with Gantry
1 by default, but is designed specifically for
the implementation of new advanced parallel
beam scanning techniques. The new system shall
be capable of providing ulrafast multiple target repainting,
without increasing beam size or treatment time.
The idea is to provide IMPT in the whole body,
i.e. also on moving targets, to establish beam
scanning as a general beam delivery technique.
Another goal is to use optional collimators
and compensators in addition to scanning, to
simulate and thus substitute passive scattering systems.
To achieve these goals we make use of
the dynamic control of the beam intensity at
the ion source, i.e. to paint the dose by changing
the intensity of the beam like in a television
set. To achieve a true volumetric target repainting
we change dynamically the energy of
the beam in small range steps with a fast degrader
by tuning the beam line in a time scale of less than 100
ms.
The
key notions for the future clinical development
of Gantry 2 can be summarized as follows:
- The capability to apply volumetric ultrafast target
repainting
- The capability to simulate scattering with advanced scanning techniques (without needing collimators and compensators)
- Easy access to the patient in treatment position
at any time
- Capability to deliver intentionally non-homogeneous
dose distributions
- To provide intensity modulated therapy with
protons as general standard for all tumor locations
- To adapt best modern image- and biological-guided
radiotherapy with protons
- Maximal clinical friendliness of the proposed
solution
- To reduce investement and operational costs, but on the same time keeping highest standard of treatment quality
Gantry 2, with in-room sliding-CT, 2011 (copyright@PSI)
