Decreased SID causes image:

Decreasing the Source-to-Image Distance (SID) in radiography can lead to magnification of the object being imaged. This occurs because when the distance between the radiation source and the detector is reduced, the object appears larger on the image than it actually is. This magnification effect happens due to the geometry of the radiation projection; as the source moves closer to the object, the divergent rays emanating from the source spread out over a larger area on the detector, resulting in an increase in size on the image.

This principle is fundamental in medical imaging and helps technicians understand how to adjust their techniques to achieve the desired level of detail and accuracy in images. Recognizing that a smaller SID increases the risk of magnification is crucial for ensuring the correct interpretation of radiographs, as it directly affects the dimensions and relationships of anatomical structures visualized in the images.