Final answer:
The X-ray beam should be collimated to decrease radiation exposure and enhance image quality.
Step-by-step explanation:
When taking a diagnostic radiograph, the X-ray beam should be collimated to decrease radiation exposure and enhance image quality. Collimation refers to the process of restricting the X-ray beam to only the area of interest, thereby minimizing unnecessary exposure to radiation for the patient and reducing the scatter of X-rays that can degrade the image quality.