To become licensed as a nurse, a social worker or even to drive around dead bodies in Maryland, a criminal background check is required.

But not to get a doctor's license.

Instead, the state Board of Physicians asks would-be doctors to voluntarily disclose arrests and convictions.

That could change as soon as next year. Already considering a background check policy, the board may move more urgently following news that it granted a medical license to a doctor with a previous rape conviction who now has been charged with sexually assaulting a patient in Allegany County.

State health officials won't say how Dr. William Thomas Dando obtained his license in 1996, less than a decade after he was found guilty of breaking into a woman's home and raping her at gunpoint. But the state's top health official acknowledged that it's likely because they weren't aware of it.

"It's hard to imagine a board knowingly doing that," Health Secretary Joshua Sharfstein said of the state's granting the license.

Patient and physician advocates questioned how it could have occurred.

"We entrust physicians with our bodies, and we don't want to entrust people who commit sexual assault," said Lisae C. Jordan, executive director of the Maryland Coalition Against Sexual Assault. "Clearly the voluntary disclosure is not working."

Even nonviolent offenses like drunken driving or other misdemeanors can be enough to make the board reconsider awarding a license, or to choose to take a license away, said Gene Ransom, executive director of MedChi. But Ransom said he could think of only a handful of cases in which someone with a felony conviction was granted a medical license during his 17-year career at the state medical society.

"There better be a really good explanation," Ransom said of Dando's licensure. "They're very hesitant to give anybody a license who has committed a felony."

Christine Farrelly, the board's acting executive director, said officials there are discussing a background check policy that could be proposed in the fall, amid a broader set of reforms in recent years to address problems including lengthy backlogs of complaints.

State auditors and the state health department have recommended before that the board use background checks before licensing doctors. Licensing boards overseeing nurses, therapists, social workers and mortuary drivers all have moved in recent years to perform background checks.

"Data suggest that a small number of physicians do not self-report criminal convictions as required on license application and renewal forms," auditors wrote in a 2007 review of the board.

But the physicians board has resisted adoption of a background check policy, said Sen. Joan Carter Conway, who said she has raised the issue amid other medical regulation reform. Dando's case likely will erode any resistance, the Baltimore Democrat said.

"Something had to happen to bring this to light. If he hadn't had this incident, they probably would still not know to this day" about Dando's rape conviction, she said. "I think this will push it."

Maryland was one of 13 states that did not conduct background checks on physicians as of September 2013, according to the Federation of State Medical Boards.

The application to get a doctor's license in Maryland includes a section regarding a person's character and fitness to work as a physician. Among the questions is one about past arrests, guilty pleas and convictions; if any are disclosed, Farrelly said, the board may request additional information and review them on a case-by-case basis.

But state law prohibits board officials from disclosing how individual physicians answered such questions, she said. She would not say how Dando answered the question.

The board does not discuss its investigations unless they result in disciplinary actions.

Dando, 59, was indicted by a grand jury May 23 on two charges related to an incident in April at an urgent-care center in LaVale, just west of Cumberland. A 41-year-old woman told police she was assaulted in a locked examination room. Dando was released and is scheduled to appear in court next month.