Patent ID: 8129701
Filing Date: 2012-03-06
Classification: A61N

Abstract:
1. A radiation therapy machine comprising: a patient support; a source of a proton radiation providing an area beam directed toward a patient on the patient support to expose tissue of the patient, an areal modulator positioned between the source of proton radiation and the patient support providing: (i) a radio-opaque plate extending over an area of the area beam and having a plurality of channels dispersed in two dimensions within the area for passing proton radiation, each channel being separated from adjacent channels by an associated portion of the radio-opaque plate bordering the channels, and the associated portion of the radio-opaque plate blacking passage of the proton radiation; (ii) adjustable intensity attenuation elements located in each of the channels to independently attenuate the intensity of proton radiation passing through the channels, wherein each adjustable intensity attenuation element is disposed wholly within an area defined by the channel and the associated portion of the radio-opaque plate bordering the channel; wherein the intensity attenuation elements provide a variable blocking of the channels to vary the intensity of the proton radiation passing through the channels; (iii) energy attenuation elements located in each of the channels to independently attenuate the energy of proton radiation passing through the channels; wherein the energy attenuation elements include an opening extending along an axis of the channels to hold attenuating fluid and connected to at least one valve system configured to adjust a height of a floating piston defining a boundary between the attenuating fluid and a second non-attenuating fluid disposed within each attenuation opening, the floating piston configured to move and adjust the height of attenuating fluid along the axis to concurrently vary the energy of the proton radiation passing through multiple channels and maintain a fluid level in response to rotational movement of the channels about the patient support, and wherein the channels are spaced with respect to each other so that divergence of the proton radiation after passing through the radio-opaque plate overlaps to permit substantially contiguous exposure of the tissue of the patient over an area corresponding to the area of the channels and the area of the portion of the radio-opaque plate bordering the channels at a given gantry angle.