The Center for Proton Therapy is a high-tech hub

Céline Giustranti
The Centre de Protonthérapie at Institut Curie offers an ultra-precise form of radiotherapy used to treat certain adult and childhood cancers. This level of precision requires cutting-edge equipment along with an expert team.

Proton therapy is an ultra-precise form of radiotherapy, radiating tumors with high precision while protecting the healthy organs close to the tumor. This ultra-precise technology is indicated for treating children in particular, since it comes with a lower risk of side-effects, as well as for certain adult cancers such as eye tumors.

Fitted treatment rooms

The Centre de Protonthérapie has three treatment rooms: one for ophthalmological and intra-cranial treatments, where the patient is seated; one where the patient is reclining or seated, for intra-cranial treatments; and one equipped with an isocentric arm for treatments in the reclining position, for intra-cranial locations and/or other parts of the body.

In the two treatment rooms where the proton beam is fixed and horizontal, the patient is placed on a table or chair, depending on the beam. In order to be able to choose the placement of the beam in relation to the lesion, the patient is placed on a table or robotized chair for ultra-precise positioning.

The room with the isocentric arm lets the beam move 360°. As the patient reclines on a treatment table, the beam is then positioned very precisely.

The proton accelerator

The proton accelerator is a circular accelerator, known as a cyclotron. The proton source – hydrogen plasma – is located at the center of the acceleration chamber. The protons are accelerated using an intense electrical field reaching 230 MeV (million electrovolts) before being channeled in a vacuum to the treatment rooms.

The physical advantage and clinical benefit of protons

The benefit of protons is essentially ballistic. The proton is a heavily charged particle, which deposits its energy along its trajectory before stopping suddenly at a certain point and delivering a high energy charge.

Beyond this point, the dose is almost zero. The proton tends to go straight and sideways diffusion is low, so that the dose delivered to the tissues surrounding the tumor is slight. It is possible to achieve the optimum dose to the tumor without exceeding the maximum admissible dose to the healthy, sensitive adjacent tissues, helping reduce the risk of deferred side effects occurring several weeks to several years after radiation.