| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce variation in beam size with respect to a position in depth-direction even when the depth-direction size of an area to be irradiated when irradiating an object to be irradiated with particle beams. Ž<P>SOLUTION: The particle beam irradiator includes a range shifter 20 having an assembly of boards attenuating energy of the particle beams, and having: a group of boards 20 to 29 of a thickness expressed by the product t×(i-1)<SP>2</SP>of a unit thickness t and 2<SP>(i-1)</SP>, when i is a continuous natural number of not less than 1 and not more than n; and two boards 30 of a thickness expressed by t×(n-1)<SP>2</SP>. The boards 20 to 30 are provided at right angle to the advancing direction 34 of the particle beams, and provided in a movable manner to a position shielding the path of the particle beam respectively independently. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
|
