Patent ID: 9707411
Date: 2017-07-18
CPC Classifications: A61N,G01T

Claim:
1. A proton radiation installation adapted to subject a target to irradiation by a proton radiation beam, said installation comprising: a target support configured to support a target; a proton radiation apparatus adapted to emit a proton radiation pencil beam along a beam axis to irradiate the target supported by the target support, said radiation beam penetrating into the target, wherein the radiation apparatus has a control system at least comprising a beam penetration depth control allowing at least to control and vary the penetration depth of the radiation beam into the target, a radiation beam range sensor device adapted to determine the penetration depth of said radiation beam into the target, wherein said range sensor device comprises multiple gamma cameras responsive to prompt gamma rays that are emitted while said radiation beam penetrates into the target, each of said gamma cameras comprising: a slit collimator having a wall that blocks gamma radiation and a single elongated slit aperture having a length between 15 and 35 centimeters in said wall, a detector comprising one or more scintillation elements upon which gamma radiation passing through said aperture of the collimator is incident, and an electronic readout mechanism associated with said detector, wherein the slit aperture has non-parallel faces defining an opening angle of the slit aperture of at most 30° and a corresponding field of view, wherein said detector has a length at least equal to the length of said slit aperture and a width perpendicular to said slit of at least 25 centimeters, wherein said gamma cameras of the radiation beam range sensor device each provide a single slit aperture, and wherein said gamma cameras are arranged in a helical arrangement relative to the beam axis such that, when seen in a plane transversely to the beam axis, said slit apertures are arranged at different angular positions relative to the target support, and such that, when seen in axial direction of the beam axis, said slit apertures are arranged at axially spaced positions relative to the beam axis, wherein axial spacing between successive single slit apertures is at least 3 centimeters and at most 10 centimeters, each slit aperture providing said field of view having an opening angle of at most 30°, which field of view is intersected by the pencil beam in operation of the installation, the fields of view provided by said successive slit apertures adjoining and partly overlapping one another so as to establish a continuous field of view along a section of the beam axis.