关键词： 空间分辨率；衬度分辨率；衍射增强成像；相衬显微 CT ；病理影像诊断

中图分类号： R814.42 文献标示码 : A

Principle and Advancements of X Ray Phase Contrast Micro-imaging

CHEN Zhi-hua 1 , PAN Lin 1 , LI Hong-yan 1 , LI Gang 2 , XU Bo 1 , WANG Zi-qiang 1 ,

ZHU Pei-ping 2 , ZHAO Tian-de 1 , JIANG Xiao-ming 2 , WU Zi-yu 2 TANG Jin-tian 1 ,

CHEN Wei-chang 1 *

(1. China Japan Friendship Hospital, China Japan Friendship Institute of Medical Sciences, Beijing 100029;

2. Institute of High Energy Physics, Chinese Academy, Beijing 100049)

Abstract: Recent development of the medical imaging is the changing from macro-imaging to the micro-imaging by improving the spatial resolution and the contrast resolution of the soft tissues. Cells and microstructure of μm magnitude can be visualized in vivo non-invasiv el y and dynamically by medical micro-imaging technique. Medical micro-imaging is capable of making the pathological diagnosis more early and the treatment of the leision more precisely by γ knife. Because the phase contrast resolution of X ray in soft tissues is about one thousand times higher than that of the absorption X ray method, so the phase contrast imaging is becoming the hot spot of the medical imaging. In this paper, the synchrotron X ray source at BSRF was used to investigate the microstructure of lung, liver and kidney by means of the DEI phase contrast micro-imaging method. Results indicated that the microstructures of lung alveoli, renal tubulous, liver lobules etc, which could not be seen by conventional absorption X ray method but could be revealed clearly by phase contrast imaging method. The spatial resolution reached about 20 μm. It is concluded that the medical phase contrast micro-CT is a new developing technique of the medical imaging in the near future.

Key words: spatial resolution; contrast resolution; Diffraction Enhancement Imaging (DEI);

Phase contrast micro-CT; image pathological diagnosis

• 当前医学影像学的发展趋势

• 1 病理学诊断与现代医学 病理学诊断是临床医学诊断的“金标准”（ golden criteria ）。病理学可分为宏观的病理解剖学和微观的细胞病理学两大类。病理解剖学即尸检，其空间分辨率为毫米数量级，是肉眼可见的分辨率范围。病理解剖学能够对病变的部位及大小进行定位和定量的诊断，但对病变性质的准确诊断，仍必需依赖组织切片和显微镜的观察，即所谓微观病理学亦即细胞病理学，才能作出精确的定性诊断。光学显微镜的空间分辨率为微米数量级，能够看见人体细胞和微细的组织结构。但由于可见光的穿透力很差，不能看见人体内部的结构和组织，因此病理的手术或穿刺的活体检查诊断都是有创的。

• 医学影像学与临床医学诊断 1895 年 X 射线的发现以及 1971 年 X 射线 CT 技术的发展　　　　　使医学活体成像技术，亦即医学影像学得到飞速发展 , 它是应用穿透力很强的射线源，例如 X 射线（ X 射线照相及 X 射线 CT ），γ射线（ PET ， SPECT ），强磁场加高频电磁波（ MRI ），超声波等透过人体内部，与深部组织结构产生相互作用，再通过计算机图像重构而显示活体内部结构或功能的影像。但目前医学影像学的空间分辨率只达到毫米数量级，仍是肉眼可见的分辨率范围，例如 X-CT 的分辨率为 0.3 ～ 0.5mm ， MRI 约为 0.5mm ， PET 为 5mm 左右，只能对病变的部位及大小进行定位和定量的诊断，尚不能进行精确的病理学定性诊断，仍属于宏观影像学（ macro-imaging ）的水平。因此当前医学影像学的发展趋势，是向微观影像学（ micro-imaging ）的方向发展 [1] 。微观影像学的空间分辨率为微米数量级，能够看见微米级的细胞和组织结构，能在活体上无损和动态地观察人体内部器官的微细病理变化，从而能早期作出准确的细胞病理学的定位和定性诊断。结合γ刀， X 射线刀及质子射线束等聚焦照射技术，早期对病变进行精确定点清除治疗，使疾病得以早期诊断，治疗，及时根治。

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