BOSTON — Cape Cod Healthcare will take your donation in U.S. dollars — and now, in cryptocurrency. Twice this year, an anonymous donor has given the company $400,000 worth of bitcoin, a virtual form of payment managed by a computer network called a blockchain. The donation had little precedent in the world of health care, said Chris Lawson, Cape Cod Healthcare’s senior vice president and chief development officer. As cryptocurrency use becomes more popular, he said, the organization soon could be a first of many. “I think what’s going to occur — without having a crystal ball — is that more and more charities are going to recognize that this is a real opportunity in terms of building philanthropic support,” he said.