Spatial resolution detector size

Molecular sieves arc used in various applications in nuclear medicine. For example, small beads of zeolites were soaked in a solution of radioactive ions. These zeolite beads are employed as point source markers for the identification of anatomical landmarks and for gamma camera uniformity. Due to their small size and relatively high uptake they provide excellent devices for measuring spatial resolution, detector unifonnity and energy resolution.[54] Zeolites are also utilized as binding agents for toxic compounds and antioxidant for selenium, vitamins, and provitamins, and arc also used as mineral additive in various dietary strategies.[55]... 

Fig. 16.2a,b. In-stent lumen imaging, a Imaging of a stent phantom acquired on a conventional 16-detector-row scanner with a voxel size of 1 mm. A conventional cobalt-chromium alloy bare metal stent (Multi-Link Vision Rx Coronary Stent System, Boston Scientific, Gatwick, Mass.) with thin struts (0.08 mm) is used, b The same stent as in a is visualized with a fourfold-better spatial resolution (voxel size of 0.25 mm), utilizing a flat-panel detector. (Modified according to Mahnken et al. 2005)... 

Other limitation for the spatial resolution can be found in the detector. A limited number of pixels in the camera array can be a reason for pure resolution in the case of a big field of view. For example, if field of view should be 10 by 10 nun with camera division 512x512 pixels the pixel size will be approximately 20 microns. To improve the relation of the field of view and the spatial resolution a mega-pixel sensor can be used. One more limitation for the spatial resolution is in mechanical movement (rotation) of the object, camera and source. In the case of a mechanical movement all displacements and rotations should be done with accuracy better than the spatial resolution in any tested place of the object. In the case of big-size assemblies and PCB s it is difficult to avoid vibrations, axle play and object non-planarity during testing. 

The Cameca ims 1280 is an ion microscope as well as an ion microprobe. That means that it can transmit direct ion images to an image detector. This capability has now been adapted for semi-quantitative and quantitative ion imaging. Direct ion imaging does not depend on the size of the primary ion beam for its spatial resolution. The new solid-state SCAPS detector has a spatial resolution of less than a micron, close to that of the NanoSIMS (see below). 

Oscillation photography can be used in tandem with area detectors, but detector resolution limits the size of the unit cell from which data can be collected. Large unit cells, such as those of virus capsids, mean small reciprocal unit cells and large numbers of closely spaced reflections. Image plates are commonly used in such cases because of their greater spatial resolution. 

We have utilized a performance metric that is suitable for comparing the imaging performance for large spatial areas of two different systems. The figure of merit we employ is the number of pixels per minute (pixpm) that can be recorded for specified data quality (SNR of absorbance spectra) at defined spectral and spatial resolution, apodization and wavelength bandpass. Since the SNR of recorded data can be anticipated to scale with the data acquisition time (as V ), the adjustment allows for easy comparisons of detectors with different sizes and performance. Consider the comparison between two detectors in terms of the ratio of their pixpm output as... 

As far as the sheet image scanner is concerned, another remaining issue is spatial resolution, which is currently 36 dpi. To improve the resolution we must reduce the size of both organic transistors and organic photo detectors. Reduction of device dimensions is not very difficult, but the bottleneck is the size of via interconnections. To reduce the diameter of via holes, we are currently working very hard to replace a CO2 laser with other short wavelength lasers, for example excimer lasers and/or YAG lasers. We believe that 600 dpi would be feasible in the near future. 

The acquisition mode (detector pixel width, number of projections and scan time) was optimized for CSCT acquisition. Assuming a point source, in CT the spatial resolution is mainly given by the size of the detector pixels, whereas in CSCT it is given by the detector pixel size, the length of the collimator lamellae in front of the detector and the distance between the object and the detector. In the experiment presented here, the combined effects of detector and collimation resulted in an average spatial resolution of 8 mm. Therefore, only a low-resolution image can be expected from the reconstruction, and consequently a low number of projections is sufficient. 

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