4 Innovations Improving Pediatric Radiation Therapy

The Radiation Oncology Program at Children’s Hospital Los Angeles is one of only a few in the country to care exclusively for children. The team combines extensive expertise with advanced technology to deliver precision treatments—aiming to maximize cure while minimizing late effects.

CHLA Radiation Oncologist Kenneth Wong, MD, and Medical Physicist Arthur Olch, PhD, FAAPM, also work with the Children’s Oncology Group consortium to design and implement pediatric radiation clinical trials across the country. In addition, Dr. Olch serves on the steering committee of Pediatric Normal Tissue Effects in the Clinic (PENTEC), an international group creating evidence-based guidelines for pediatric radiation therapy.

Dr. Olch and Dr. Wong, along with Eric Lin Chang, MD, Professor and Chair of Radiation Oncology at USC, share three innovations that are impacting pediatric radiation care today—and a fourth that is on the horizon.

1. Spatially fractionated radiation therapy

This therapy has been available for decades in adults, but today’s technologies have vastly improved it. Children’s Hospital Los Angeles recently became one of the first institutions in the world to use it in pediatric patients.

Specifically for patients with large, bulky tumors, spatially fractionated radiation therapy delivers high-dose radiation only to small, centralized areas within the tumor—not the entire mass. In studies, this technique has been shown to induce dramatic responses in the whole tumor, with minimal side effects.

“It’s not completely understood why this happens, but we think we are creating an immune response,” Dr. Olch explains. “The high-dose radiation may attract T-cells, which then go on to kill a much bigger area of the tumor.”

CHLA has so far treated six patients through a close collaboration with Hualin Zhang, PhD, Associate Professor of Clinical Radiation Oncology at the Keck School of Medicine of USC, an expert in this therapy in adults.

“In large part we are able to offer this treatment because of our collaboration with USC,” Dr. Wong explains. “Often the newest developments in radiation therapy occur for adults first, and this partnership helps us more quickly adapt them to pediatrics.”

2. Volumetric modulated arc therapy

CHLA is also one of the few centers providing volumetric modulated arc therapy (VMAT) for children with leukemia who need total body irradiation before bone marrow transplantation.

Under conventional methods, patients are treated from about 10 feet away with a single radiation beam. But this can deliver too-high doses to the lungs, leading to serious complications such as pneumonitis.

VMAT uses intensity modulated radiation therapy to deliver customized doses of radiation to different parts of the body. This allows much lower doses to be delivered to the lungs. Radiation doses are also much more accurate with VMAT.

“As a result of being able to lower the dose to the lungs, this method may also allow us to deliver higher radiation doses elsewhere in the body for patients who have the highest-risk cancers,” Dr. Wong notes.

Through their involvement in the Children’s Oncology Group, Dr. Wong and Dr. Olch are helping other radiation oncology departments implement VMAT for children. In addition, the team—which treated its first two patients last December as part of a clinical trial—is establishing a VMAT registry study at CHLA.

“This is going to be a big shift in how children with leukemia receive total body irradiation,” Dr. Olch says. “Right now, only a few places are doing it, but in five years I think this will be the standard of care.”

3. Child-friendly head immobilization

CHLA developed this novel system two decades ago but remains one of the only centers in the country using it. Specifically for children with brain or head or neck tumors, the system uses a vacuum-assisted mouthpiece to immobilize a child’s head during radiation treatment for head and neck tumors.

The system replaces the standard thermoplastic mesh mask that completely covers and conforms to the patient’s face to prevent the head from moving.

“The mask can be claustrophobic and very scary for a child, who is often treated daily for several weeks,” Dr. Olch says. “Our mouthpiece is well tolerated by even the youngest children, and it’s actually more accurate in preventing head movement. In addition, if a child is sedated, the anesthesiologist has full access to the child’s airway if needed.”    

4. Personalized medicine

This advance has not yet been realized—but the team agrees this is where the field is headed.

“We’re entering an era of personalized medicine on all fronts, including pediatric radiation oncology,” says Dr. Chang of USC. “We’re going to be refining patient selection based on molecular markers that predict the disease behavior and can help us determine how aggressive or intensive our treatments should be.”

For example, CHLA is participating in a Children’s Oncology Group clinical trial that is investigating whether radiation doses can be reduced in patients who have a favorable genetic profile for certain cancers.

“The ultimate goal is to select the patients who don’t need radiation therapy at all,” Dr. Chang says. “That’s difficult to do, and it needs more study, but the hope is that more molecular markers will be available to help us make these decisions and personalize care for each child.”