A soft x-ray microbeam using proton-induced x-ray emission (PIXE) of characteristic titanium (K(α) 4.5 keV) as the x-ray source has been developed at the Radiological Research Accelerator Facility (RARAF) at Columbia University. The proton beam is focused to a 120 μm × 50 μm spot on the titanium target using an electrostatic quadrupole quadruplet previously used for the charged particle microbeam studies at RARAF. The proton induced x-rays from this spot project a 50 μm round x-ray generation spot into the vertical direction. The x-rays are focused to a spot size of 5 μm in diameter using a Fresnel zone plate. The x-rays have an attenuation length of (1/e length of ~145 μm) allowing more consistent dose delivery across the depth of a single cell layer and penetration into tissue samples than previous ultra soft x-ray systems. The irradiation end station is based on our previous design to allow quick comparison to charged particle experiments and for mixed irradiation experiments.

中文翻译：

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哥伦比亚大学质子诱导的软 X 射线微束。

哥伦比亚大学放射研究加速器设施 (RARAF) 开发了一种使用特征钛 (K(α) 4.5 keV) 的质子诱导 x 射线发射 (PIXE) 作为 x 射线源的软 x 射线微束。质子束使用先前用于 RARAF 带电粒子微束研究的静电四极杆四极杆聚焦到钛靶上的 120 μm × 50 μm 点。来自该点的质子诱导 X 射线将 50 μm 圆形 X 射线产生点投射到垂直方向。使用菲涅耳波带板将 X 射线聚焦到直径为 5 μm 的光斑大小。X 射线的衰减长度为（1/e 长度约 145 μm），与以前的超软 X 射线系统相比，可以在单个细胞层的深度上提供更一致的剂量并穿透组织样本。