(The recently FDA-approved Gamma Knife Icon, Elekta's latest incarnation of the system, is head-frame optional, however.)

“We are treating almost all of the brain metastases patients [at our hospital] with [RapidArc] right now because we do not need to put a head frame on them and that is a major comfort for the patient. There is no needle or anesthesia [required],” said Shi.


While there is value — both for patients and providers — in a faster, less invasive treatment, Shi said that CMS reimburses brain tumor treatments the same whether Gamma Knife or RapidArc is used.

There are others who see the slightly-better dose specificity of Gamma Knife as sufficient evidence that it's a superior treatment and, despite the discomfort involved, believe it ultimately yields better outcomes.

Last year, HCB News spoke to Dr. Lijun Ma, a physicist from the UCSF radiation oncology department, who participated in a study comparing brain cancer treatment modalities at six different clinics to better understand the pros and cons of each one.

Like Shi's team, they found that Gamma Knife had slightly better dosimetry at the expense of a lengthier treatment. For Ma, this illustrated that Gamma Knife could yield better outcomes.

"The entire backbone of doing radiosurgery is to be precise,” said Ma. “Once you target the lesion [with the head frame], it’s easy to be very precise.”

The body movements that a computer mapping system has to account for — such as rotational shifts, breathing, sweating, even gravity — are infinitely complex and can result in reduced accuracy of the treatment, according to Ma.

As for a definitive answer on which system is best for treating brain metastases?

"In the end, using one or the other doesn't make a significant clinical difference and that is important to know, because physicians and patients now know they have a choice of treatments," said Shi.

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