Joy Keo, the Northern Virginia teen-ager whose former boyfriend was convicted in the shooting that left her paralyzed, yesterday filed a $30 million civil lawsuit against the man, two psychiatrists who had treated him, and the manufacturer of the handgun that he used in the shooting.

The suit, filed in Fairfax Circuit Court by Keo and her mother, asks $15 million in compensatory damages, including lifetime medical expenses for Keo, and $15 million in punitive damages.

The suit names not only Charles R. Brewer Jr., 20, who is serving a 50-year sentence for the shooting that left Keo a quadriplegic, but his father and brother as well.

Also named as defendants are Dr. David L. Charney of Alexandria, Dr. Martin H. Stein of the Dominion Psychiatric Treatment Center in Falls Church, the center, and Smith and Wesson Inc., manufacturers of the .38-caliber snub-nosed pistol.

"I am completely dependent on other people," 17-year-old Joy Keo told reporters at the courthouse, "and dependency costs money. That's the one thing we don't have."

Her mother, Marion (Keophumihae) Keo, said that her daughter requires 24-hour care.

"We have attendants who come in three-hour shifts to bathe her and feed her, to get her dressed and into the wheelchair in the morning . . . to do the little things we take for granted, like scratching her nose or brushing her hair," said Marion Keo. "It's expensive . . . and when I'm dead, who's going to take care of her?"

Joy Keo also said she was "very afraid" that Brewer would pursue her after his release. Brewer will be eligible for parole in nine years.

The lawsuit contends that Brewer's father, C. Robert Brewer, who owns a sporting goods store in Springfield, and Brewer's brother Craig negligently failed to prevent Brewer from taking the handgun from their store.

The suit also claims that the Smith and Wesson Model 36 is "inherently and abnormally dangerous." It further alleges that the model is commonly used in criminal activities, and the use of the gun "by persons such as" Brewer was "forseeable."

Suits brought against manufacturers of handguns, seeking to hold the companies liable for damage caused by the pistols they make, are a relatively recent development. Lawyers for White House press secretary Jim Brady and others wounded in the attempted assassination of President Reagan by John Hinkley are suing Roehm/RG Industries, a West German arms company.

A Smith and Wesson spokesman said that he had not been notified of the suit, and declined to comment.

Brewer's father said yesterday that he was "not surprised" by the Keos' suit. Brewer said that he also intends to sue the psychiatrists, who he believes wrongly diagnosed and prescribed for his son.

Neither Dr. Stein, who is in Europe, nor Dr. Charney could be reached for comment.