From the Guidelines
The main controlling factor for shape distortion in X-ray imaging is the object-to-image receptor distance, which significantly affects the magnification and distortion of the object's shape. When an object is positioned farther from the image receptor, the magnification and distortion of its shape increase significantly due to the divergent X-ray beam 1. This occurs because X-rays travel in straight lines from the source, creating a divergent beam that projects the object's shadow onto the receptor. As the distance between the object and receptor increases, the X-ray beam has more space to diverge, resulting in a larger and more distorted image.
Key Factors Influencing Shape Distortion
- Object-to-image receptor distance: The primary factor controlling shape distortion, as it directly influences the degree of beam divergence and subsequent image magnification 1.
- X-ray beam angle: Although not the main controlling factor, the angle of the X-ray beam relative to the object and receptor can also contribute to shape distortion.
- Source-to-image distance: Maintaining an optimal source-to-image distance, typically around 70 cm, is crucial for minimizing distortion while ensuring patient safety and image quality 1. To minimize shape distortion in radiographic imaging, technologists should position the object of interest as close as possible to the image receptor while maintaining an appropriate source-to-image distance. This principle is particularly important when accurate measurements or proportions are needed for diagnosis, such as in orthopedic imaging.
From the Research
Main Controlling Factor for Shape Distortion in X-Ray
- The main controlling factor for shape distortion in x-ray is not explicitly stated in the provided studies, however, it can be inferred that distortion is a significant issue in x-ray imaging 2, 3.
- Studies have shown that time instability of the imaging chain is a major source of variability in dewarp results, which can lead to shape distortion 2.
- Geometric image distortion in the x-ray imaging chain can be corrected using global or local techniques, with the global technique being more accurate and robust 3.
- Other factors that can affect shape distortion in x-ray imaging include the type of distortion (radial or sigmoidal), the local direction of the distortion gradient, and the pixel size 3.
- Metal implants can also cause artefacts in x-ray computed tomography (CT) scans, which can lead to shape distortion, and various techniques have been proposed to reduce these artefacts 4.