Methods While we knew the shape,orientation and SAD of the fields;by calculating the divergence angle and rotating the gantry,collimater,table within the angle to modulate the fields.

• 方法在已知某一照射野大小、方向和源轴距的情况下,计算出射线束发散的夹角,并依照该角度对机架角、准直器和治疗床做出相应的旋转调整。