To see him smile and giggle, you'd think 2-1/2-year-old Kaiden Brennfoerder of Plano hadn't a care in the world.
But the scar slicing across his skull shows there's a lot on the minds of his parents.
In March, Amy and Brian Brennfoerder walked into Kaiden's room to find his whole body convulsing in a seizure.
"That was pretty scary," Brian recalled. "That was on a Thursday that he had the seizure. So on Monday, he had brain surgery."
"They told us he had a mass the size of a golf ball in the front left part of his brain," Amy said, remembering the moment her son was diagnosed with a rare brain cancer called a supratentorial peripheral neuroectodermal tumor.
"It just kind of changes everything," Brian said, taking a deep breath.
Five months ago, Kaiden had surgery in Dallas to remove that aggressive brain cancer.
Then followed chemotherapy.
And now has come the fear of radiation.
"With any kind of radiation, you're gong to have stunted growth, memory loss, a drop in IQ, they could potentially get ADHD," Amy said. "Just all kinds of problems later in life."
Instead of standard radiation, his parents sought out a cutting-edge treatment three hours north, in Oklahoma City. The treatment is called proton therapy.
At the ProCure facility, Kaiden receives super-targeted high-dose radiation five days a week for 30 days.
Traditional radiation is like a shotgun blast, damaging tissue on its way to the cancer and on the other side.
Proton therapy involves a beam of particles charged to travel a precise distance.
"It will stop on a dime and it will release all its energy at that point," explained radiation oncologist Dr. Sameer Keole. "Proton therapy is more like a firecracker. You can put the radiation right in the middle of the cancer. Do a lot of damage to the cancer, but do very little damage to the surrounding tissues."
Dr. Keole says the advantages include fewer long and short-term side effects from radiation.
"Because there's less dose to normal structures, patients can tolerate the treatments better," Dr. Keole said. "For patients who work, there's less chance of missing days of work."
Proton therapy isn't recommended for all cancers, but it can work on many different types, in adults and children.
Some radiation experts dispute that proton therapy is any better than lower-cost, widely available radiation treatments.
For pediatric brain cancers like Kaiden's, the upsides are strong, given children are especially susceptible to the negative effects of radiation therapy.
"The advantages are incredible," said Dr. Keole. "For Kaiden, we'll be able to decrease the dose to the healthy, uninvolved brain by 90 percent. We'll have absolutely no dose to the pituitary gland, to the hypothalamus, to the eyes -- to all of these normal critical structures, there will be zero dose, and that's a huge advantage."
The big disadvantage or proton therapy is cost.
A facility like ProCure, where Kaiden is being treated in Oklahoma City, costs more than $100 million to build. That's because projecting the high-powered proton beam requires importing a 220-ton particle accelerator called a cyclotron which is encircled by 16-feet of solid concrete.
There are only eight proton therapy facilities in the United States. The only one in Texas is at MD Anderson Cancer Center in Houston.
Treatment can be three to 10 times more expensive than traditional radiation. Insurance companies often refuse to pay for it.
Even if insurance had not covered Kaiden's cost, his parents say they would have found a way.
"He's going to outlive all of us," Brian said, "so whatever side effects he has from whatever therapies or treatments he has, he's going to have to live with those. So if we can make those as little as possible, for him, it's worth it."
"We knew that if we had a chance to give him a better quality of life after this, we were going to take it," Amy added.
Halfway through treatment, proton therapy seems to be working. No one has noticed any side effects, or any difference in Kaiden's sharp mind.
It's hoped the only reminder Kaiden will have of this experience and his brain tumor will be that scar -- one day covered with hair.