C Liu et al et al 1993)and magnetic resonance imaging(MRI(Orel et al 1997). Mammography is currently recognized as the gold standard for the early detection of breast cancer because it requires lower radiation doses, though the rate of false negatives is still as high as 10 per cent (Wilkinson et al 2005). Recently, some new techniques, such as digital mammography, computer aided diagnosis, synchrotron mammography and digital tomosynthesis have been developed to optimize image quality and improve the diagnostic capabilities( Giammarile and Bremond 2004, Niklason et al 1997). The synchrotron radiation, which is electromagnetic by charged particles moving with a speed very close to light speed in a circular orbit, was first found in 1947 and then widely used in different fields, including material science, biology, medicine(Margaritondo and Meuli 2003, Suortti and Thomlinson 2003), etc. Images obtained by using synchrotron radiation with higher spatial resolution and better contrast( Fiedler et al 2003)are superior to those with a conventional x-ray source. With synchrotron radiation, some microstructures inside organic tissues can be shown, which are often missed with conventional techniques Since the middle of the 1990s, x-ray phase-contrast imaging techniques, which can clearly show the microstructure of biological soft tissues under low radiation dose, have been quickly developed (Lewis et al 2002). Diffraction enhanced imaging (DED, whose contrast comes from the absorption, the refractive gradient and the small-angle scattering rejection(usually called extinction), is one of them(Hasnah et al 2002, Zhong et al 2000). The DEl method enhances the sharpness and clarity of the soft tissue image relative to the traditional method due to the combination of more contrast mechanisms(Menk 1999). In recent years, DEI has shown some latent applications in early diagnosis(Lewis 2004). The spatial resolution of DEl images is higher than that of B-mode ultrasound, MRI or CT(computer tomography), and reaches the order of micrometres (Liu et al 2005). The combination of DEl and ct (also called DEI-CT)makes medical images of tumours extraordinarily similar to pathological histology ( Fiedler et al 2004). Moreover, due to the high intensity of synchrotron radiation, only a short exposure time(see below) is needed. Therefore, synchrotron radiation based DEl has a low risk of complications due to the radiation exposure which is obviously an advantage in the early diagnosis of cancer. 6. In this paper, we compared various DEI images of the tissues for the normal breast, benign breast tumour and malignant breast tumour along with their rocking curves to distinguish the microstructures inside those tissues, and we also discussed the merits of this technique for medical applications 2. Materials and methods The specimens were prepared in the Cancer Hospital, Medical Center of Fudan University. We selected 13 of them, including four cases of normal breast tissue, four cases of benign breast tumour tissue and five cases of breast cancer tissue. Both the diseased tissues and the healthy ones were taken from mastectomy sufferers. The main part of each cancer tissue included a great mass of cancer nests, and the normal tissue was taken from a distance of about 2 cm beside the tumour. These specimens were cut into small pieces of 10 x9 mm with a thickness of approximately 2 mm and fixed in 10% buffered formalin. The DEl experiments have been carried out at the topography end station of the 4WiA beamline of the Beijing Synchrotron Radiation Facility(BSRF). The energy of the monochromatic x-rays was 9 keV with an incident angle of 12.7, and the maximum size of the light spot was approximately 12 x 10 mm" at the position of specimen. The analyser was fixed at the axis so it could be tuned to get the different positions of the rocking curve. The DEl images were recorded using a CCD with 1300 x 1030 pixels(X-ray Fast Digital Imager420 C Liu et al et al 1993) and magnetic resonance imaging (MRI) (Orel et al 1997). Mammography is currently recognized as the gold standard for the early detection of breast cancer because it requires lower radiation doses, though the rate of false negatives is still as high as 10 per cent (Wilkinson et al 2005). Recently, some new techniques, such as digital mammography, computer aided diagnosis, synchrotron mammography and digital tomosynthesis have been developed to optimize image quality and improve the diagnostic capabilities (Giammarile and Bremond 2004, Niklason et al 1997). The synchrotron radiation, which is electromagnetic radiation emitted by charged particles moving with a speed very close to light speed in a circular orbit, was first found in 1947 and then widely used in different fields, including material science, biology, medicine (Margaritondo and Meuli 2003, Suortti and Thomlinson 2003), etc. Images obtained by using synchrotron radiation with higher spatial resolution and better contrast (Fiedler et al 2003) are superior to those with a conventional x-ray source. With synchrotron radiation, some microstructures inside organic tissues can be shown, which are often missed with conventional techniques. Since the middle of the 1990s, x-ray phase-contrast imaging techniques, which can clearly show the microstructure of biological soft tissues under low radiation dose, have been quickly developed (Lewis et al 2002). Diffraction enhanced imaging (DEI), whose contrast comes from the absorption, the refractive gradient and the small-angle scattering rejection (usually called extinction), is one of them (Hasnah et al 2002, Zhong et al 2000). The DEI method enhances the sharpness and clarity of the soft tissue image relative to the traditional method due to the combination of more contrast mechanisms (Menk 1999). In recent years, DEI has shown some latent applications in early diagnosis (Lewis 2004). The spatial resolution of DEI images is higher than that of B-mode ultrasound, MRI or CT (computer tomography), and reaches the order of micrometres (Liu et al 2005). The combination of DEI and CT (also called DEI-CT) makes medical images of tumours extraordinarily similar to pathological histology (Fiedler et al 2004). Moreover, due to the high intensity of synchrotron radiation, only a short exposure time (see below) is needed. Therefore, synchrotron radiation based DEI has a low risk of complications due to the radiation exposure which is obviously an advantage in the early diagnosis of cancer. In this paper, we compared various DEI images of the tissues for the normal breast, benign breast tumour and malignant breast tumour along with their rocking curves to distinguish the microstructures inside those tissues, and we also discussed the merits of this technique for medical applications. 2. Materials and methods The specimens were prepared in the Cancer Hospital, Medical Center of Fudan University. We selected 13 of them, including four cases of normal breast tissue, four cases of benign breast tumour tissue and five cases of breast cancer tissue. Both the diseased tissues and the healthy ones were taken from mastectomy sufferers. The main part of each cancer tissue included a great mass of cancer nests, and the normal tissue was taken from a distance of about 2 cm beside the tumour. These specimens were cut into small pieces of 10 × 9 mm with a thickness of approximately 2 mm and fixed in 10% buffered formalin. The DEI experiments have been carried out at the topography end station of the 4W1A beamline of the Beijing Synchrotron Radiation Facility (BSRF). The energy of the monochromatic x-rays was 9 keV with an incident angle of 12.7◦, and the maximum size of the light spot was approximately 12 × 10 mm2 at the position of specimen. The analyser was fixed at the axis so it could be tuned to get the different positions of the rocking curve. The DEI images were recorded using a CCD with 1300 × 1030 pixels (X-ray Fast Digital Imager