Particle beam irradiation apparatus and control method of the particle beam irradiation apparatus

1. A particle beam irradiation apparatus comprising:

a beam generation portion that generates a particle beam;

a beam emission control portion that controls emission of the particle beam;

a beam scanning portion that two-dimensionally scans the particle beam;

a sensor portion including a plurality of first linear electrodes arranged in parallel in a first direction and a plurality of second linear electrodes arranged in parallel in a second direction orthogonal to the first direction;

a beam shape calculation portion that calculates a center of gravity of the particle beam from a first signal output from each of the first linear electrodes and a second signal output from each of the second linear electrodes and that obtains a two-dimensional beam shape of the particle beam around the center of gravity from the first and second signals;

a storage portion that accumulates and stores the two-dimensional beam shapes corresponding to the center of gravity across a range of the two-dimensional scan; and

a display portion that displays the two-dimensional beam shapes of the range of the two-dimensional scan stored in the storage portion, as a two-dimensional distribution of a particle beam dose.

2. The particle beam irradiation apparatus according to claim 1 , wherein

the beam shape calculation portion

obtains the two-dimensional beam shapes from amplitude values of a plurality of the first and second signals around the center of gravity.

3. The particle beam irradiation apparatus according to claim 2 , wherein

the beam shape calculation portion

obtains a first beam shape on an axis in the first direction and a second beam shape on an axis in the second direction from the amplitude values of the plurality of first and second signals around the center of gravity and obtains a beam shape in an area other than the two axes based on a product of the first beam shape and the second beam shape to obtain the two-dimensional beam shape.

4. The particle beam irradiation apparatus according to claim 1 , wherein

the beam shape calculation portion

obtains a dispersion of a position from amplitude values of a plurality of the first and second signals around the center of gravity and sets a Gaussian distribution shape determined by the center of gravity and the dispersion as the two-dimensional beam shape.

5. The particle beam irradiation apparatus according to claim 4 , wherein

the beam shape calculation portion

obtains a first dispersion at a position in the first direction and a second dispersion at a position in the second direction from the amplitude values of the plurality of first and second signals around the center of gravity,

sets s first beam shape on an axis in the first direction as a first Gaussian distribution shape determined by the center of gravity and the first dispersion, sets a second beam shape on an axis in the second direction as a second Gaussian distribution shape determined by the center of gravity and the second dispersion, and

obtains a beam shape of an area other than the two axes based on a product of the first beam shape and the second beam shape to obtain the two-dimensional beam shape.

6. The particle beam irradiation apparatus according to claim 1 , wherein

the beam scanning portion

two-dimensionally scans slices by the particle beam, the slices obtained by dividing an affected area to be irradiated in an axial direction of the particle beam,

the storage portion

accumulates and stores, slice by slice, the two-dimensional beam shapes across a range of the two-dimensional scan, and

the display portion

displays, slice by slice, the two-dimensional beam shapes as a two-dimensional distribution of a particle beam dose.

7. A control method of a particle beam irradiation apparatus comprising a sensor including a plurality of first linear electrodes arranged in parallel in a first direction and a plurality of second linear electrodes arranged in parallel in a second direction orthogonal to the first direction, the control method comprising the steps of:

controlling emission of a particle beam;

two-dimensionally scanning the particle beam;

calculating a center of gravity of the particle beam from a first signal output from each of the first linear electrodes and a second signal output from each of the second linear electrodes;

obtaining a two-dimensional beam shape of the particle beam around the center of gravity from the first and second signals;

accumulating and storing the two-dimensional beam shapes corresponding to the center of gravity across a range of the two-dimensional scan; and

displaying the accumulated and stored two-dimensional beam shapes of the range of the two-dimensional scan, as a two-dimensional distribution of a particle beam dose.

8. The control method of the particle beam irradiation apparatus according to claim 7 , wherein

in the step of obtaining the two-dimensional beam shape,

the two-dimensional beam shape is obtained from amplitude values of a plurality of the first and second signals around the center of gravity.

9. The control method of the particle beam irradiation apparatus according to claim 8 , wherein

in the step of obtaining the two-dimensional beam shape,

a first beam shape on an axis in the first direction and a second beam shape on an axis in the second direction are obtained from the amplitude values of the plurality of first and second signals around the center of gravity, and a beam shape in an area other than the two axes is obtained based on a product of the first beam shape and the second beam shape to obtain the two-dimensional beam shape.

10. The control method of the particle beam irradiation apparatus according to claim 7 , wherein

in the step of obtaining the two-dimensional beam shape,

a dispersion of a position is obtained from amplitude values of a plurality of the first and second signals around the center of gravity, and a Gaussian distribution shape determined by the center of gravity and the dispersion is set as the two-dimensional beam shape.

11. The control method of the particle beam irradiation apparatus according to claim 10 , wherein

in the step of obtaining the two-dimensional beam shape,

a first dispersion at a position in the first direction and a second dispersion at a position in the second direction are obtained from the amplitude values of the plurality of the first and second signals around the center of gravity,

a first beam shape on an axis in the first direction is set as a first Gaussian distribution shape determined by the center of gravity and the first dispersion, a second beam shape on an axis in the second direction is set as a second Gaussian distribution shape determined by the center of gravity and the second dispersion, and

a beam shape of an area other than the two axes is obtained based on a product of the first beam shape and the second beam shape to obtain the two-dimensional beam shape.

12. The control method of the particle beam irradiation apparatus according to claim 7 , wherein

in the step of two-dimensionally scanning,

slices are two-dimensionally scanned by the particle beam, the slices obtained by dividing an affected area to be irradiated in an axial direction of the particle beam,

in the step of accumulating and storing,

the two-dimensional beam shapes are accumulated and stored, slice by slice, across a range of the two-dimensional scan, and

in the step of displaying,

the two-dimensional beam shapes are displayed, slice by slice, as a two-dimensional distribution of a particle beam dose.