Hi, Reison, and welcome to the forum:
When I was diagnosed, my doctor -- an otoneurologist -- immediately ruled out radiation. He said I needed surgery, and fast. He was misinformed on both counts. I subsequently had a consultation with a neurosurgeon who also advised against radiation; his reasoning was based on data that was roughly 40 years old. That is, although he was a brain surgeon, he was entirely ignorant about the last several decades worth of data about success rates with radiation. Yet another neurosurgeon -- this one, a lot more open-minded -- admitted that I knew a lot more about radiotherapy than he (because of all the research I had done). But the bottom line is that I chose CyberKnife (CK) radiation treatments in the end (for my AN), and my treatments were incredibly successful. (My tumor shrank over 70%, my balance recovered at least 80% and my tinnitus decreased in volume around 90%; YMMV.)
You owe it to yourself to get an expert opinion from a doctor who specializes in radiotherapy (e.g., CK) or radiosurgery (like GammaKnife) for treating acoustic neuromas. Dr. Steven D. Chang is one of the world's leading CK practitioners. He operates out of Stanford University Medical Center in California and will review your MRI and give you his recommendation for free. His email address is sdchang@stanford.edu.
Your tumor is very very small. If you've only had one MRI so far, then you should probably wait 6 months until you get a followup MRI before you consider getting any type of treatment. The second MRI will tell you whether or not your tumor is growing. Some ANs stay the same size for decades and needn't be treated. I also have a hypoglossal schwannoma (tumor on the 12th cranial nerve); it hasn't needed treatment because it has stayed the same size for the past 5 years (possibly longer; it was only discovered 5 years ago).
No matter what you do, please get a second opinion from an expert in radiation treatments. Then you'll have both sides of the story and can choose which approach feels right for you.
Best wishes,
TW