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首页> 外文期刊>Acta crystallographica.Section D. Biological crystallography >Know your dose: RADDOSE.
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Know your dose: RADDOSE.

机译：知道你的剂量:RADDOSE。

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摘要

The program RADDOSE is widely used to compute the dose absorbed by a macromolecular crystal during an X-ray diffraction experiment. A number of factors affect the absorbed dose, including the incident X-ray flux density, the photon energy and the composition of the macromolecule and of the buffer in the crystal. An experimental dose limit for macromolecular crystallography (MX) of 30 MGy at 100 K has been reported, beyond which the biological information obtained may be compromised. Thus, for the planning of an optimized diffraction experiment the estimation of dose has become an additional tool. A number of approximations were made in the original version of RADDOSE. Recently, the code has been modified in order to take into account fluorescent X-ray escape from the crystal (version 2) and the inclusion of incoherent (Compton) scattering into the dose calculation is now reported (version 3). The Compton cross-section, although negligible at the energies currently commonly used in MX, should be considered in dose calculations for incident energies above 20 keV. Calculations using version 3 of RADDOSE reinforce previous studies that predict a reduction in the absorbed dose when data are collected at higher energies compared with data collected at 12.4 keV. Hence, a longer irradiation lifetime for the sample can be achieved at these higher energies but this is at the cost of lower diffraction intensities. The parameter 'diffraction-dose efficiency', which is the diffracted intensity per absorbed dose, is revisited in an attempt to investigate the benefits and pitfalls of data collection using higher and lower energy radiation, particularly for thin crystals.
机译：程序RADDOSE被广泛用于计算剂量被大分子晶体在吸收x射线衍射实验。因素影响的吸收剂量,包括入射x射线通量密度,光子的能量和大分子的组成在晶体内部缓冲区。限制大分子晶体学(MX)30在100 K MGy报道,超过这个可能获得的生物信息妥协。优化的衍射实验评估的剂量已成为一个额外的工具。在原始的近似版本的RADDOSE。为了考虑修改荧光x射线逃离水晶(版本2)和不连贯(康普顿散射)剂量计算现在报告(第三版)。康普顿横截面,尽管可以忽略不计的能量目前常用的MX,应该考虑剂量计算事件高于20 keV能量。3 RADDOSE加强先前的研究预测时的吸收剂量的减少数据被收集在更高的能量相比12.4 keV收集的数据。辐照一生为示例在这些更高的能量,但这是在实现衍射强度较低的成本。参数“diffraction-dose效率”,它是衍射强度每吸收剂量重新调查数据收集的好处和缺陷较高和较低的能量辐射,特别是对薄晶体。

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