Table of Contents
Trento Proton Therapy Center (TPTC)
References
Beam Parameters
| Beam Source | Particle Type | Flux ($cm^{-2} s^{-1}$) | Energy | Notes |
|---|---|---|---|---|
| Cylotron (operated by IBA Company) | proton | $3.8*10^6$ to $2.3*10^8$ | 70.2MeV to 228.2MeV | Beam with Gaussian intensity profile. Gaussian peak and sigma change with energy. |
Facility
The Trento Proton Therapy Center (TPTC) is a dedicated facility for treating tumors with protons. The facility is equipped with two rooms: i) for patient treatments and ii) for experimental purposes (physics and/or biophysics). Protons are supplied by a Cyclotron with an energy of 230 MeV. These are then extracted and focused into a graphite-made energy degrader where the proton energy can be decreased to 70 MeV. The beams can then be redirected into the gantry rooms for patient treatment (offset by $30^{o}$ from the beam line) or into the “Experimental Cave”. There the beamlines can be used for in-air irradiation (see figure below).
The beam flux and width depend on the proton energy. Their dependency/correlation is listed in the table below
| Energy (MeV) | Average $\sigma$ (mm) | Flux (p/s) |
|---|---|---|
| 70.2 | 6.92 | $3.8 \times 10^6$ |
| 100 | 5.68 | $1.2 \times 10^7$ |
| 142.9 | 4.56 | $3.6 \times 10^7$ |
| 169.4 | 4.00 | $7.4 \times 10^7$ |
| 202.4 | 3.48 | $1.4 \times 10^8$ |
| 228.2 | 2.73 | $2.3 \times 10^8$ |
The correlation between beam profile and flux results from the stopping material which lowers the beam energy.
Irradiation Configuration
Three beam configurations are possible:
- small dual ring =⇒ circumference of ~3 cm radius with flat intensity profile medium beam intensity
- large dual ring =⇒ circumference of ~8 cm radius with flat intensity profile low beam intensity
- high beam intensity: direct beam irradiation configuration. Irradiation performed with non uniform intensity beam. The gaussian profile of the beam can be tuned changing the beam energy.
For the dual ring configuration, incoming protons exit the beam pipe and then pass through foil. It then passes through the dual ring which changes the beam profile from a gaussian into a flat profile. The circumference of the beam can have a radius of either 3cm or 8cm. The maximum fluence (per day) is $\approx 5.0 \times 10^{11} p/cm^2$.
In a direct proton beam irradiation the maximum amount of beam can be delivered on the target. However, the beam transverse intensity distribution is gaussian instead of uniform. The gaussian's sigma can be tuned from 2.73 mm up to 6.92 mm, decreasing the beam energy from 228MeV down to 70MeV.
Beam Application
Since the TPTC is a medical facility the beam in the experimental area is available only at the end of medical treatment, that is from ~19.30 up to 22:30 Mon-Fri, 8-13 on Sat. Formal requests should be done through this link.