The $10 million deal for Calypso Medical Technologies by Varian Medical Systems (NYSE:VAR) leaves a lot to be desired for Calypso’s legacy investors – namely, about $140 million.

Backers have poured more than $150 million into the Seattle-based company and its tumor-tracking technology since its 1999 inception.

Although the Varian deal includes earn-outs pegged to sales over the 30 months after the deal closes, one of its earliest investors told the Seattle Times that the deal is “disappointing, to say the least.”

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“It will live on, and people with prostate and lung and other terrible cancers will have something that was created in Seattle,” Joseph Piper, of Seattle’s Integra Ventures, told the newspaper. “There’s a lot that got accomplished in that company, and someone is going to make a lot of money. Unfortunately it’s not going to be the legacy shareholders.”

The decision to sell came after Calypso couldn’t drum up any more cash for building a sales team and conducting clinical trials, Piper said. The company, led by president & CEO Edward Vertatschitsch, reeled in a $7.5 million funding round this year, but the economic climate made any more infusions unlikely, he said.

Varian, however, “can use all of its strength to take the technology forward and broadly apply it,” according to Vertatschitsch. “They are expecting to invest in the technology and take it the final mile.”

Calypso won an investigational device exemption from the FDA for a clinical trial evaluating the technology for tracking lung tumors during radiation treatments. A component of the system, its dynamic edge gating technology, won 510(k) clearance in October 2010. And in January, Calypso reeled in a $6.4 million installment on its way to closing out the $7.5 million round.