B Dot Medical Inc.

Yuichi Saraya

Takuji Furukawa

Yousuke Hara

Kota Mizushima

Ryohei Tansho

Eri Takeshita

Naoya Saotome

An embodiment of the invention is a focusing magnet including a coil pair arranged on both sides of a path of a charged particle beam. The coil pair generates an effective magnetic field region in which a magnetic field is oriented in a direction (z-axis) perpendicular to a traveling direction (x-axis) of a charged particle beam. In an xy-plane, an incident charged particle beam deflected at a deflection angle &#x3d5; with respect to the x-axis at a deflection point Q is deflected by the effective magnetic field region, and irradiates an isocenter at an irradiation angle &#x3b8; with respect to the x-axis; an arbitrary point Pon a boundary on an exit side of the effective magnetic field region is at an equal distance rfrom the isocenter; a point Pon a boundary on an incident side of the effective magnetic field region and the point Pare on a radius rand an arc of a central angle (&#x3b8;+&#x3d5;); and when a distance between the deflection point Q and the isocenter is L, a distance R between the deflection point Q and the point Psatisfies a relational equation (4).

Focusing magnet and charged particle irradiation apparatus

An embodiment of the invention is a focusing magnet including a coil pair arranged on both sides of a path of a charged particle beam. The coil pair generates an effective magnetic field region in which a magnetic field is oriented in a direction (z-axis) perpendicular to a traveling direction (x-axis) of a charged particle beam. In an xy-plane, an incident charged particle beam deflected at a deflection angle &#x3d5; with respect to the x-axis at a deflection point Q is deflected by the effective magnetic field region, and irradiates an isocenter at an irradiation angle &#x3b8; with respect to the x-axis; an arbitrary point P2 on a boundary on an exit side of the effective magnetic field region is at an equal distance rfrom the isocenter; a point P1 on a boundary on an incident side of the effective magnetic field region and the point P2 are on a radius rand an arc of a central angle (&#x3b8;+&#x3d5;); and when a distance between the deflection point Q and the isocenter is L, a distance R between the deflection point Q and the point P1 satisfies a relational equation (4).

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Chiba, Japan

Yuichi Saraya