Size and shape distortion can be created through a variety of different techniques. If you as a radiology technologist are not careful, you can create a visual of something that might not be true about a patient. For example, if you are not careful, an improper SID can create size distortion. This can be seen in chest X-rays when a technologist uses 40 inch SID instead of 72: they can create the illusion of cardiomegaly, which is fancy talk for enlarged heart. If a patient is diagnosed with a condition because of improper imaging procedures, it can cause harm to the patient. Another factor that can increase magnification is things like OID. Object to Image Distance is something that can increase the size of an image and make the part appear larger than it actually is. The more distance between the IR and the patient, the larger the magnification will be.
When looking at shape distortion, something as simple as improper alignment of the X-ray tube can cause an image to appear one way or another. Shapes can either be foreshortened or elongated, and when aligning the patient and the CR, it is important to keep the anatomy in mind. As radiology technologists, we are taught the proper alignment for different procedures. In this, we are taught how to align the Central Ray to the part to the IR. This is crucial because there are some alignments that enable the radiologist to be able to see joint spaces and other important landmarks. Below shows what a different CR can make a standard coin look like when it is exposed.
X-ray X-pert 