When is an X-ray used vs. an MRI/ultrasound/CT scan?

The x-ray frequently comes first because it's more available in general practice. It's also generally less expensive than advanced imaging or even ultrasound. So that may come into play if we feel like that will give us a high yield for less cost. We would also use that primarily for the big picture, like if we want to look at the whole abdomen or the whole chest, and we're not looking at a specific organ. For lameness or suspicions of trauma with fractures, that's where I feel like x-rays would kind of trump the others.