system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why do mammograms require the breasts to be squished flat when we are able to take X-rays and ultrasounds through fat and muscle masses?

I’ve never had a mammogram so I actually don’t know how it works. Only heard the jokes about how they squish your breasts and that it hurts. We were talking about how men can have breast cancer so why don’t they get mammograms? (Maybe they do). Then we laughed as we pretended to slip a tiny man boob into an imaginary mammogram machine (that I’ve never seen).

So I thought they can do X-rays and stuff. Why do they *have* to torture you to get the results. Did some sick doctor invent the machine, laughing the whole time about how evil and unnecessary it is? /s 

Biology tag? Idk.
gpt
X-rays are partially absorbed as they travel through flesh.  They are slightly more absorbed in some lumps, but it's not the "broken bone" sort of X-ray you might be thinking of.  To get enough contrast to spot lumps, the X-ray beam needs to be tuned to the amount of flesh it's passing through.  That's made a lot simpler by squishing the breast into a slab of uniform-ish thickness.  Since the natural shape is more hemispherical, some force is required.  The breast is also well instrumented with nerves, so the force can be painful.