Has anyone tried scalp injection treatment for hair loss on the crown of their head?

I've recently become interested in hair loss treatment because I feel like the hair on the crown of my head has thinned noticeably. When I visited the hospital, they told me that injection treatment could also be considered after checking my scalp condition.

However, getting an injection directly into the scalp is more daunting than I thought. I'm also curious about the level of pain and how many sessions I would need.

For those of you who have received scalp injection treatment, did you actually notice your hair becoming thicker or denser? The cost seems quite high, so I would like to hear about your experiences before I start.