Particle therapy device and method for setting dose calibration factor

Patent metadata

Field	Value
Publication number	US-2016008631-A1
Application number	US-201314771444-A
Country	US
Kind code	A1
Filing date	Jun 6, 2013
Priority date	Jun 6, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

An irradiation apparatus radiates a particle beam after forming the beam for plural layers. A dose monitor measures a dose in real time. A dose evaluation unit evaluates an irradiation dose for each layer on the basis of a value measured by the dose monitor and a dose calibration factor set for each layer. An irradiation control section performs radiation control for each layer on the basis of an evaluation result of the dose evaluation unit. An interpolation value generation unit uses actual-measurement dose-calibration factors obtained by radiating a particle beam to a simulated phantom provided with a calibration dosimeter, to generate an interpolation estimation value of the dose calibration factor. For each layer subject to the interpolation value, and based on an irradiation condition of that layer, the interpolation value generation unit performs weighting on each of the actual-measurement dose-calibration factors.

First claim

1 - 9 . (canceled)

10 . A particle therapy device in which an irradiation target is partitioned into a plurality of layers in order of depth from a body surface, and irradiation is performed while an irradiation dose is controlled for each of the layers, comprising:
an irradiation apparatus that radiates a particle beam supplied from an accelerator, after forming the beam for said each of the layers; a dose monitor that is placed in the irradiation apparatus and measures a dose in real time; a dose evaluation unit that evaluates the irradiation dose for said each of the layers on the basis of a dose that is calculated using a measurement value measured by the dose monitor and using a dose calibration factor set for said each of the layers, and a dose determined by a treatment plan; an irradiation control device that controls a irradiation amount to said each of the layers on the basis of an evaluation result of the dose evaluation unit; and an interpolation value generation unit that uses actual-measurement dose-calibration factors each obtained by radiating a particle beam to a simulated phantom provided with a calibration dosimeter, to thereby generate an interpolation value or an estimation value of the dose calibration factor for at least one of the layers for which the actual-measurement dose-calibration factor is not obtained; wherein, for each layer subject to the interpolation value or the calibration value, based on an irradiation condition of that layer, the interpolation-value generation unit performs weighting on each of the actual- measurement dose-calibration factors.

11 . The particle therapy device according to claim 10 , wherein, when generating the interpolation value or the calibration value for the layer whose depth is deeper than a predetermined value, the interpolation value generation unit performs said weighting so that a weight of the actual-measurement dose-calibration factor at a deep layer among the actual-measurement dose-calibration factors is larger than a weight of the actual-measurement dose-calibration factor at a shallow layer there among.

12 . The particle therapy device according to claim 10 , wherein:
a range shifter for adjusting energy of the particle beam is provided in the irradiation apparatus, and the interpolation value generation unit performs said weighting on the basis of at least one condition from among the energy of the particle beam emitted from the accelerator, a thickness of the range shifter and a material thereof.

13 . The particle therapy device according to claim 11 , wherein:
a range shifter for adjusting energy of the particle beam is provided in the irradiation apparatus, and the interpolation value generation unit performs said weighting on the basis of at least one condition from among the energy of the particle beam emitted from the accelerator, a thickness of the range shifter and a material thereof.

14 . The particle therapy device according to claim 10 , wherein:
a wobbler electromagnet for enlarging a diameter of an irradiation field of the particle beam is provided in the irradiation apparatus, and the interpolation-value generation unit performs said weighting on the basis of the enlarged diameter.

15 . The particle therapy device according to claim 11 , wherein:
a wobbler electromagnet for enlarging a diameter of an irradiation field of the particle beam is provided in the irradiation apparatus, and the interpolation-value generation unit performs said weighting on the basis of the enlarged diameter.

16 . The particle therapy device according to claim 12 , wherein:
a wobbler electromagnet for enlarging a diameter of an irradiation field of the particle beam is provided in the irradiation apparatus, and the interpolation-value generation unit performs said weighting on the basis of the enlarged diameter.

17 . The particle therapy device according to claim 13 , wherein:
a wobbler electromagnet for enlarging a diameter of an irradiation field of the particle beam is provided in the irradiation apparatus, and the interpolation-value generation unit performs said weighting on the basis of the enlarged diameter.

18 . A method for setting a dose calibration factor that is used in a particle beam therapy in which an irradiation target is partitioned into a plurality of layers in order of depth from a body surface and irradiation is performed while an irradiation dose is controlled for each of the layers, and that is for calculating a dose in the irradiation target using a measurement value of a dose monitor placed in an irradiation apparatus; said method comprising:
a step of radiating a particle beam to a simulated phantom provided with a calibration dosimeter to thereby obtain actual-measurement dose-calibration factors each using a depth of the calibration dosimeter in the simulated phantom as a parameter, on the basis of the measurement value of the dose monitor and a measurement value of the calibration dosimeter; and an interpolation value generation step of establishing a mathematical function of the dose calibration factor having the depth as a variable, on the basis of the actual-measurement dose-calibration factors, to thereby generate an interpolation value or an estimation value of the dose calibration factor corresponding to a layer for which the actual-measurement dose-calibration factor is not obtained; wherein, in the interpolation value generation step, for the layer subject to the interpolation value or the calibration value, based on an irradiation condition corresponding to that layer, weighting is performed on each of the actual-measurement dose-calibration factors.

19 . The method for setting a dose calibration factor according to claim 18 , wherein, in the interpolation value generation step, at the time of generating the interpolation value or the calibration value for the layer whose depth is deeper than a predetermined value, said weighting is performed so that a weight of the actual-measurement dose- calibration factor at a deep depth of the calibration dosimeter among the actual-measurement dose calibration factors, is larger than a weight of the actual-measurement dose-calibration factor at a shallow depth thereof.

20 . The method for setting a dose calibration factor according to claim 18 , wherein:
in the particle beam therapy, energy of the particle beam is adjusted using a range shifter; and in the interpolation value generation step, said weighting is performed on the basis of at least one condition from among the energy of the particle beam emitted from an accelerator, a thickness of the range shifter and a material thereof.

21 . The method for setting a dose calibration factor according to claim 19 , wherein:
in the particle beam therapy, energy of the particle beam is adjusted using a range shifter; and in the interpolation value generation step, said weighting is performed on the basis of at least one condition from among the energy of the particle beam emitted from an accelerator, a thickness of the range shifter and a material thereof.

22 . The method for setting a dose calibration factor according to claim 18 , wherein:
in the particle beam therapy, a diameter of an irradiation field of the particle beam is enlarged by a wobbler electromagnet; and in the interpolation value generation step, said weighting is performed on the basis of the enlarged diameter.

23 . The method for setting a dose calibration factor according to claim 19 , wherein:
in the particle beam therapy, a diameter of an irradiation field of the particle beam is enlarged by a wobbler electromagnet; an

Assignees

• Mitsubishi Electric Corp

Inventors

• Harada Hisashi
• Ikeda Masahiro
• Takahashi Osamu
• Ina Nobuhiko
• Pu Yuehu
• Iwata Takaaki

Classifications

• A61N5/1075 Primary

  for testing, calibrating, or quality assurance of the radiation treatment apparatus · CPC title

• A61N2005/1087

  Ions; Protons · CPC title

• A61N5/1071

  for verifying the dose delivered by the treatment plan · CPC title

• A61N5/1067 Primary

  in real time, i.e. during treatment · CPC title

• A61N2005/1076

  using a dummy object placed in the radiation field, e.g. phantom · CPC title