They’re known as Buster hugs, typically dispensed after the Giants win a World Series or throw a no-hitter. On such occasions, catcher Buster Posey races joyously to the mound and wraps his arms around the pitcher, just about squeezing the air out of the poor fellow.

It turns out Buster hugs aren’t confined to the baseball diamond. Posey takes them on the road when he visits young cancer patients, as he did Thursday at John Muir Medical Center in Walnut Creek.

“Can I get a hug?” he asked 7-year-old Mayah Pisciotto, of Antioch, whose acute lymphoblastic leukemia is in remission.

The answer, of course, was yes.

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“Got anything for me to sign?” Posey asked after the hug.

Mayah coyly pulled back the blanket on her bed to reveal several baseballs and miniature bats, eliciting raucous laughter in the room.

Pediatric cancer, and the need to raise awareness for funding and research, is a cause near and dear to the hearts of Posey and his wife, Kristen, who spent about 90 minutes meeting with patients and staff at the hospital where their twins were born in 2011. The couple was drawn to the cause by an acquaintance whose son has cancer.

“It was something we followed for a couple of years,” Posey said. “We both just kind of said, we’re in a unique situation and have a platform, so if we can help, let’s try to help.”

“I couldn’t just look away from this,” Kristen Posey said. “I told Buster, ‘Let’s stop talking about it and let’s do something.’ “

Earlier this year, the Poseys began visiting hospitals and inviting patients and their families to Giants games. They are keenly aware that only 4 percent of all cancer funds raised in the United States are funneled to pediatric cancer. They are planning a fundraising event in September.

“It’s still a learning process for us,” Buster Posey said. “We’re still trying to figure out the best way we can do that. Just taking time trying to make a kid smile I think is really cool.”

Posey, as down-to-earth as Newton’s apple, is a natural at the meet-and-greet game.

His first stop at John Muir was a room with five starry-eyed patients, one of whom, Samantha Smith, 6, of Danville, was holding a sign that read “Samantha (hearts) Buster.”

“Samantha?” Posey said excitedly. “That’s my sister’s name.”

Asked about the origin of his first name, Posey told 10-year-old patient Annabella Keenan, of Livermore, and her twin brother, Thomas:

“That’s a good question. It’s not my real name, but I’ve been called that since I was born. It’s kind of a good baseball name. But when you’re 10, not so good.”

Posey brought caps and placards to sign and distributed collapsible clothes hampers, which, when the lid is lifted, reveal an image of Posey in a catcher’s mask with glove in position to receive a Madison Bumgarner fastball.

“Just throw right at my glove,” he told the kids. “You’ll never throw your clothes on the floor again.”

Posey patiently posed for countless photos — many for hospital staff members — and signed dozens of autographs. He took impromptu tours of hospital facilities from administrators who are rightfully proud of their facility. In August, U.S. News & World Report ranked John Muir Health’s medical centers in Walnut Creek and Concord among the top 15 in the state.

Last year, John Muir established a partnership with Stanford Children’s Health, which allows East Bay children to receive treatment locally rather than have to drive to Palo Alto.

Mayah’s room was one of Posey’s last stops.

“It means everything,” said Austin, Mayah’s mother, of the ballplayer’s visit. “He’s a true inspiration. I know that he’s involved in pediatric cancer awareness. Without people like him, we wouldn’t have such amazing doctors and treatments. Mayah’s cancer has a 90 percent cure rate. Five years ago, that was not the case.”

“I’ve been blessed to do something I love,” Posey said. “And not only do what I love but be a positive impact for families and for kids. It’s something that I think we’ll do for the rest of our lives.”

Do you have a column topic for Gary? Contact him at 925-952-5053 or gpeterson@bayareanewsgroup.com. Follow him at Twitter.com/garyscribe.