Dose fractionation theorem in 3-D reconstruction (tomography)
- Lawrence Berkeley National Lab., CA (United States)
It is commonly assumed that the large number of projections for single-axis tomography precludes its application to most beam-labile specimens. However, Hegerl and Hoppe have pointed out that the total dose required to achieve statistical significance for each voxel of a computed 3-D reconstruction is the same as that required to obtain a single 2-D image of that isolated voxel, at the same level of statistical significance. Thus a statistically significant 3-D image can be computed from statistically insignificant projections, as along as the total dosage that is distributed among these projections is high enough that it would have resulted in a statistically significant projection, if applied to only one image. We have tested this critical theorem by simulating the tomographic reconstruction of a realistic 3-D model created from an electron micrograph. The simulations verify the basic conclusions of high absorption, signal-dependent noise, varying specimen contrast and missing angular range. Furthermore, the simulations demonstrate that individual projections in the series of fractionated-dose images can be aligned by cross-correlation because they contain significant information derived from the summation of features from different depths in the structure. This latter information is generally not useful for structural interpretation prior to 3-D reconstruction, owing to the complexity of most specimens investigated by single-axis tomography. These results, in combination with dose estimates for imaging single voxels and measurements of radiation damage in the electron microscope, demonstrate that it is feasible to use single-axis tomography with soft X-ray microscopy of frozen-hydrated specimens.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- OSTI ID:
- 525915
- Report Number(s):
- LBNL-40112; CONF-9608146-; ON: DE97005928; TRN: 97:015075
- Resource Relation:
- Conference: Workshop on x-ray computed microtomography (CMT), Berkeley, CA (United States), 12-13 Aug 1996; Other Information: PBD: Feb 1997; Related Information: Is Part Of Proceedings of the workshop on high resolution computed microtomography (CMT); PB: 437 p.
- Country of Publication:
- United States
- Language:
- English
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