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What is Spatial Resolution?

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Are you ever confused when you hear of spatial recognition being mentioned by X-ray technicians

Spatial recognition is a very critical parameter of an X-ray machine that should be given careful consideration when you are in the market shopping for an X-ray machine. It becomes even more critical once the screen sizes get larger and viewing distances get closer. The efficiency of spatial resolution usually depends on the relationship between the displayed content and the compression system. Ultimately, you’ll have to consider other elements of spatial resolution beside the number of pixels. For instance, the angle made by individual pixels on the retina of the viewer.  

So, let’s take an in-depth look at spatial resolution. 


I. What is Spatial Resolution?

To begin with, spatial resolution has to do with the number of pixels that are utilized to create a digital image. If one digital image has a higher spatial resolution than another image, it means that the higher spatial resolution image is formed by more pixels than the lower spatial resolution image for the equal dimensions of the imaging part. Spatial resolution can ascertain an image’s quality and express how thorough an object can be represented by the image. Also, it is a measurement to ascertain how small an object should be for an imaging system to observe it. Additionally, in X-ray imaging, the label spatial resolution is often employed to explain the imaging resolution. The spatial resolution of an X-ray imaging system is the capacity of the system to outline tiny defects. 


What is Spatial Resolution


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II. What is Resolution in Radiology?

To understand resolution in radiology you need to think of it as a measurement. For instance, spatial resolution in X-ray images can be clarified by using two images with distinct spatial resolutions for evaluation. The capacity of a single pixel to depict a tiny flaw in a metal or other materials varies between different spatial resolutions. The tag, spatial resolution of an X-ray imaging system, is used to explain in clear terms the system’s errors in illustrating the tiny flaws. Additionally, image formation inaccuracies can incorporate both the spatial resolution (pixel resolution) of the imaging system and other systematic inaccuracies. Hence, spatial resolution is calculated in line pairs per centimeter (lp/cm) and is an estimation of the vagueness that comes from imaging formation flaws of X-ray systems.


III. Why is Spatial Resolution Important in Radiography?

Spatial resolution is quite important in radiography for many reasons basically because the whole X-ray examination and inspection rely on image analysis to identify errors, defects, and anomalies. Consequently, the quality of the image is therefore central in radiography. Also, spatial resolution is indispensable because it impacts how intensely we view objects. 

The essential variable is not solely the number of pixels in each row or column of the display, but the angle defined by each of these pixels on the viewer’s retina. From another point of view, increased spatial resolution is peculiarly essential as screen sizes get bigger and viewing areas get closer. Similarly, the effectual spatial resolution will hang on the interface between the compression system and the displayed content. It almost requires no efforts to turn HD (High definition) content into SD (Standard Definition) content using compression. And to clear a popular advertising misconception, the term referred to as “HD quality” is simply nonexistent.


IV. What Affects Spatial Resolution on an X-ray?

Various factors can affect the spatial resolution of an X-ray imaging system. Most of these factors are parameters that can be set before embarking on any sample examination. These factors include:

  • Spatial frequency – If the spatial frequency of an object is too high for the system, the system will lack the potential to display the image satisfactorily. The higher the object spatial frequency, the lower the MTF (Modular Transfer Function) until the system is unable to differentiate the line pairs which results in a homogeneous grey. 
  • Low contrast – If the object is of low contrast, the system will attain an MTF (Modular Transfer Function) of 0 earlier as the smaller contrast in the range of shades ascertains that the image will attain a homogeneous grey quicker than if it was a high contrast image (for example, alternating bands of black and white).
  • Un-Sharpness – Whatever increases the un-sharpness blurs the edges and additionally reduces the spatial frequency.
  • Sampling pitch – This is the center-to-center interspace between individual detector elements. It dictates the most spatial frequency that can be imaged. 
  • Detector aperture – For signals averaged over the area of the detector element. If the object details are tinier than the proportions of the element, they are inconspicuous except they have enough contrast to have a noteworthy effect on the average signal.



In conclusion, spatial resolution is essential in forming a digital image for inspection objectives to be complete and accurate. Therefore, spatial resolution in x-ray imaging can either adversely or favorably determine the final analysis of inspection based on the resolution of the image displayed.

In essence, spatial resolution determines inspection image analysis which further ascertains further steps to be taken and decisions to be made on component and equipment production. Furthermore, as viewing screens become larger and viewing spans are closer an increased spatial resolution creates a better image analysis.

Finally, spatial resolution can be limited by several varying factors which include low contrast, sampling pitch, and spatial frequency.


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