Colonna S, D'Acapito F, Mobilio S, Onori S, Pugliani L, Romanzetti S, Rustichelli F
CNR-GILDA crg ESRF, Grenoble, France.
Phys Med Biol. 2001 Apr;46(4):967-74.
Conventional radiographic techniques have strong limitations when low-absorption contrast samples are imaged. Phase contrast radiography has been shown to produce high-quality images of soft tissues. In this technique the recorded intensity patterns are related to gradients in the refractive index of the sample. A critical point of this new technique is the need to employ crystal analysers, which results in an appreciable reduction in the beam intensity and consequently in rather long exposure times. In this paper the use of focused beams is suggested to overcome this aspect. Biological samples with small structures and low absorption variations were imaged using both flat and curved monochromator crystals, demonstrating that the use of curved optics leads to a decrease in the exposure time with only a limited degradation of the spatial resolution. This opens up the possibility of using the phase contrast technique with laboratory sources.
当对低吸收对比度的样本进行成像时，传统的放射成像技术存在很大局限性。相衬射线照相已被证明能产生软组织的高质量图像。在这项技术中，记录的强度模式与样本折射率的梯度有关。这项新技术的一个关键点是需要使用晶体分析仪，这会导致光束强度显著降低，从而使曝光时间相当长。本文建议使用聚焦光束来克服这一问题。使用平面和弯曲单色仪晶体对具有小结构和低吸收变化的生物样本进行了成像，结果表明，使用弯曲光学元件可减少曝光时间，同时空间分辨率仅有有限的下降。这为在实验室光源条件下使用相衬技术开辟了可能性。
