Final answer:
To reduce shape distortion, increase the SID and decrease the OID.
Step-by-step explanation:
When shape distortion is undesirable, the two things that need to be done are to increase the Source-to-Image Distance (SID) and decrease the Object-to-Image Distance (OID). By increasing the SID, the image will be less distorted since the x-ray beam is more parallel to the object being imaged. Decreasing the OID also helps reduce shape distortion because the object is closer to the image receptor, resulting in less magnification.