Enhancement of X-ray Image's Resolution by using fabricated Anti Backscattered Radiation Grids
Abstract
This study aims to develop a method for enhancing x-ray image’s resolution in radiology department, some fabricated grids with significant capability in reducing backscattered radiation are used to assessment its effectiveness in improving radiographic image resolution. The fabricated anti backscattered grids are designed from different materials with different geometric shapes. Image resolution test tool is exposed to produce x-ray images at different exposure parameters (kVp, mAs). The results of resolution indexes (LP/mm) illustrated remarkable effect of anti backscattered grids in improvement of x-ray image resolution up to 32%, with the use of crossed iron steel grid. Therefore, the effectiveness of fabricated grids in enhancing image resolution is dependent on the grid’s material and design, as well as the radiation exposure parameters.
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Introduction
X-ray image is widely used in medical diagnosis; it is considered an important technique for the majority of radiological examinations (Huang, 2011). The value of x-ray image details depends on image’s resolution. Therefore, x-ray image’s resolution is a significant characteristic of radiograph quality which could be used to evaluate the capability of radiographic system in imaging two separate objects or tissues and visually distinguish one from the other. Medical imaging system with higher spatial resolution can demonstrate the presence of smaller objects in the produced image (Huda and Abrahams, 2015).
Two common ways used to evaluate the resolution properties of an imaging system are the line spread function and the modulation transfer function. Spatial resolution throughout medical imaging systems is described quantitatively by the response of the imaging system to a test device. The test pattern in X-ray radiography is called a line-pair per mm, and consists of highly absorbing lead lines with varying widths separated by interspaces of equal size between lines (Bushong, 2013; Bushberg et al., 2012; Guy and Dominic, 2005).
Spatial resolution is expressed by the number of line pairs per millimeter (lp/mm) that appear in the x-ray’s image. The measure of resolution depends on the difference in contrast between black and white lines recorded from the test pattern. The higher of this number refer to the better of the spatial resolution and smaller of object that can be imaged clearly (Huda and Abrahams, 2015; Bushong, 2013; Bushberg et al., 2012; Guy and Dominic, 2005).
Huda and Abrahams (2015) described the essential characteristics of spatial resolution and reported some factors influenced the sharpness of radiographic image including the size of the source of x-rays (focal spot), the degree of photons scatter, the physical properties of the x-ray detector system (area and thickness), the motion blur, and the image processing.
Conclusion
Radiographic image resolution can be increased by utilizing anti back scattered radiation grids under film screen combination during exposure. All fabricated anti back scattered grids proved its capability in reducing back scattered radiation which enhance image resolution. The capability of anti backscattered grids in improvement of image resolution depends on grid’s material and geometrical design, as well as exposure parameters (kVp, and mAs), the best enhancement of image resolution can be obtained by using crossed iron grid with relatively lower kVp and mAs values.