Shares in hotly-watched health care small-cap IsoRay (ISR) were on the rise again today after the company released a statement that it had received final approval from the Washington Department of Health to manufacture its liquid Cesium-131 product for use in treating brain cancers.

The news sent IsoRay’s stock up. However, while most companies would be thrilled by double-digit gains, the move is a relatively modest one compared to the last few months of trading for the volatile battleground stock IsoRay. The stock opened up 14.8 percent at $2.64 a share and, after whipsaw action in the first half-hour of trading, hit an intraday peak at $2.76 a share just before 10 am ET.

From that peak in the first half hour of trading, IsoRay cooled considerably but continued trading over $2.50 a share for gains over 10 percent on the day. The day’s gains were likely bolstered by broader market conditions as well, as biotech and growth stocks were on the rise on Monday.

Small-cap IsoRay’s liquid Cesium-131 treatment, Cesitrex, has already received regulatory approval from the FDA for use with the GilaSite balloon catheter and should be used in treating metastatic and gliboblastoma cancers in the brain. The treatment has the potential to improve on safety for both patient and staff over the current treatment using Iodine-125. It’s easier to clean up should there be a spill and doesn’t require a thyroid block.

“We are very excited to have our Liquid Cesium-131 isotope now available for use with our GliaSite® balloon catheter system,” stated CEO Dwight Babcock in the written statement. “With reimbursement codes already available, we will immediately begin offering our newest innovation to major medical centers to establish patient studies, ultimately resulting in these thought leaders reporting their study findings for peer review and publication. As a company, we are witnessing a growing adoption of our products in hospitals and medical practices nationwide. Equally important, we are proud to have reached this new milestone for patients who are searching for treatment options and hope in their fight against brain cancer.”

IsoRay’s gains come as the stock continues to search for steady footing in the markets. Since the stock skyrocketed in mid-March, the stock has routinely been among the highest-volume stocks out there with big price swings to boot. After hitting its 52-week high at $3.77 a share, the stock pulled back after the announcement of a new public offering to take advantage of the new share price, soared again, then began a longer down-trend that was reversed again when a study was published that appeared to confirm the potential for success contained in the company’s Cesium-131 brachytherapy.

On the whole, IsoRay remains a stock to watch. With almost 15 percent of its float moving each day and a stock price that seems to swing up or down 10 percent or more at the drop of a hat, it remains a volatile stock that could mean big gains or losses depending on how one plays it.