Ion-beam mask for cancer patient therapy

• US 3,886,367 A
• Filed: 01/18/1974
• Issued: 05/27/1975
• Est. Priority Date: 01/18/1974
• Status: Expired due to Term

• Current Assignee: John G. Castle Jr
• Original Assignee: John G. Castle Jr
• Inventors: Castle, John G. Jr.
• Primary Examiner(s): Lieberman, Eli
• Assistant Examiner(s): Nelms, D. C.
• Application Number:
  US05/434,458
• Time in Patent Office: 494 Days
• Field of Search: 250/494,496,505,511-514,520
• US Class Current: 250/505.1
• CPC Class Codes: A61B 6/10 Safety means specially adapted therefor
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: A61N 2005/1095 Elements inserted into the radiation path within the system, e.g. filters or wedges
• CPC Class Codes: A61N 5/10 X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy A61N5/01 takes precedence
• CPC Class Codes: G21K 1/025 using multiple collimators, e.g. Bucky screens; other devices for eliminating undesired or dispersed radiation
• CPC Class Codes: G21K 5/04 with beam-forming means

Abstract

An ion-beam mask has been provided for spatially distributing fast ions used to irradiate tumors so that the region near the Bragg peak receives a uniform radiation dose while the tissue at the point of entrance of the beam has a web of unirradiated volume to promote healing of the surface tissue following radiotherapeutic treatment of embedded tumors.

Claims

1. A radiation mask for mitigating the surface tissue effects of a radiotherapeutic treatment of embedded tumors in a patient by means of a beam of fast ions from a beam source, comprising:

a block of radiation shielding material positioned in said beam intermediate the patient and said beam source, said block having a surface area larger than the cross section of said beam and a thickness greater than the range of ions of said beam in said shielding material, said shielding material block having a plurality of circular cross section apertures extending therethrough in a direction parallel to the rays of said beam and arranged in an orderly, evenly spaced array, each of said apertures having a diameter (d) and spaced with a wall thickness (w) therebetween defined by d w F sigma e, with f being in the range of from 1 to 2 and where sigma e is the effective dispersion of the ions passing through said apertures at the depth of said embedded tumor to attain sufficient overlap of discrete beam portions passing through adjacent ones of said apertures at the depth of the Bragg peak for said beam source coincident with the tumor region, thereby providing a lateral uniformity of radiation dose over the irradiated area of said tumor while shielding a substantial are of skin and intervening tissue.

2. The radiation mask as set forth in claim 1 wherein said beam of fast ions is protons in the range of from 50 to 200 MeV and said shielding material is carbon.

3. The radiation mask as set forth in claim 2 wherein the apertures in said shield are arrayed in a hexagonal pattern.