Diverging scan

Clock skew in the scan path could result in a scan pull-through or a diverging scan chain. In other words, during the scan shift phase, due to clock skew the same scan bit can be loaded into two successive scan cells. 

In traditional Fan-Beam CT the radiation emitted from the X-ray tube is collimated to a planar fan, and so most of the intensity is wasted in the collimator blades (Fig. 2a). Cone-Beam CT, where the X-rays not only diverge in the horizontal, but also in the vertical direction, allows to use nearly the whole emitted beam-profile and so makes best use of the available LINAC photon flux (Fig. 2b). So fast scanning of the samples three-dimensional structure is possible. For Cone-Beam 3D-reconstruction special algorithms, taking in consideration the vertical beam divergence of the rays, were developed. 

Because of the low divergence, topography experiments may be conducted at a great distance (50-1000 m) from the source. This provides a wide beam at the specimen and large areas may be illuminated without the need for scanning. 

Are the results applicable to my patient Is my patient represented Were the clinically important outcomes considered How long did the treatment last Are the treatments worth the potential benefits, harms, and costs Can we provide the treatment In the Methods section, quickly scan the inclusion and exclusion ctitetia to see if yout patient falls within the type of patient enteted into the study. If necessary, adjust the NNT so that the expectations for benefit match the divergence of your patient from the average patient in the study population. Factor in your preferences and expectations and preferences of your patient and family. 

Fig. 3. X-ray diffractogram of Class-F bituminous coal fly ash. Analytical conditions diffraction data were collected using a Philips X-ray powder diffractometer (45 kV/30-40 mA CuKa theta-compensating variable divergence slit diffracted-beam graphite monochromator scintillation detector) automated with an MDI/Radix Databox. The scan parameters were typically 0.02° step size for 1 s count times over a range of 5-60° 2-theta. All data were analysed and displayed using a data reduction and display code (JADE) from Materials Data Inc., livermore, CA.

Figure 6.1 Comparison of 26 — 6 scan profiles obtained by a monochromatized (pure Cu kal) parallel beam configuration (hybrid x-ray mirror) and a conventional parallel beam configuration achieved by divergence slit (ds) module measured at 001/100 (a), 002/200 (b), 003/300 (c), 004/400 (d) of 500nm-thick Pb(Zro.B4Tio.46)03 thin film. Dotted lines represent the second derivative of the profiles, indicating the peak positions. Note that the profiles are simulated fitted profiles for obtained spectrum using pseudo-Voight function (mixed Lorentz and Gauss function).

More comprehensive studies should include other reflections and rotations around psi- (for symmetrical reflections) and phi- (for asymmetrical reflections) axes. The psi rotation is around the in-plane axis which is in the diffraction plane. The phi rotation is around the normal to the sample surface. Both psi and phi scans supply important information on the sample mosaicity, but should be corrected with respect to the instrumental function, as most diffractometers possess X-ray beams which are highly divergent in the direction perpendicular to the diffraction plane. 

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