Proton Therapy Introduction
A new radiotherapy facility for the treatment of deep seated tumors using a scanned proton beam has been assembled at PSI.
Patient treatments started at the facility in December 1996.
The purpose of the facility:
The rationale to use
protons for radiotherapy is to deliver the dose on the target volume with a better localisation than with conventional therapy with photons.
Technical features of the facility
Due to its innovative approach, this project is the technologically most advanced in the field of proton therapy nowadays.
The major technical features, which characterise the project, are the following :
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1. The spot scanning technique
The spot scanning technique provides
routinely a complete three-dimensional conformation of the dose to the target
volume.
The dose is deposited by scanning a proton pencil beam (hot spot of the dose at the Bragg peak position) directly in the patient.2. The compact isocentric gantry
The rotating beam line, the so-called
gantry ,
allows to apply the beam on the patient from any direction.
The PSI gantry is the second proton gantry operational in the world and it is smaller by about a factor of 3 compared to any other design.3. Patient handling with patient transporter
The patient handling
at PSI allows to position the patient with the help of a computer tomograph
(CT) outside the treatment room (to reduce the treatment time in the gantry
room and improve the patient throughput).
4. High quality assurance tools
The scientific environment of PSI is a fertile ground for new developments to
improve the precision of the treatment.
Examples:
Computer optimised treatment planning for 3D conformal therapy
3D-dosimetry for conformal therapy
Proton radiography
Dose error algorithms
A technology open to the future
The PSI proton gantry with spot scanning is presently the only facility,
which can deliver the dose using inverse planning methods with protons.
This capability will soon be a necessary condition for a successful competition
with the new intensity modulation techniques developed by industry in the
field of conventional therapy with photons.
