Jennifer Mathews: Dave Clark doesn't need a video store. He catches a movie every weekday at the hospital. Dave spends five days a week, 130 minutes a day, in a hyperbaric oxygen chamber to treat brain injury after radiation. He's had two brain tumors removed in the last 4 years.Dave Clark: Ironically, the day after my daughter was born, was my first day of chemo.Jennifer Mathews: Doctor Laurie Beth Gesell, a hyperbaric medicine expert, says the damaged brain tissue leads to a variety of problems.Laurie Beth Gesell: They might have numbness. They might have thinking problems. They might have speaking problems. They might have things as generalized as just severe headaches.Jennifer Mathews: Typically steroids are used to treat tissue damage. Doctor Gesell hopes breathing in a hyperbaric oxygen chamber will be a better option. The MRI on the left shows a pattern of brain tissue damage surrounded by swelling. The MRI on the right shows the difference after several months of hyperbaric oxygen therapy.Laurie Beth Gesell: For the most part, hyperbarics is an incredibly safe type of treatment. All it is, is that we have a person breathe oxygen, and we pressurize that oxygen.Jennifer Mathews: MRI's show the treatment improves nearly eighty percent of patients. Dave is one of them. And he says the movies are a bonus. This is Jennifer Mathews reporting.