On any given day thousands of patients around the world—children and adults—will get an x-ray. What they probably won’t think about while sitting on the table wearing one of those lead aprons, though, is how at that moment the same technology being used to take a picture of their arm or leg or skull is also helping an oncologist treat a cancer patient’s tumor.
X-rays—rather, the radiation used to take an x-ray—are just one example of how many of the energies used to take pictures of the body can also have direct treatment applications. Sometimes the same radiation that takes an x-ray picture is used to zap tumor cells. The difference from one to the other is merely a matter of power.
“It’s like sunshine,” explains Ellen Grant, MD, a neuroradiologist trained in theoretical physics and director of the Fetal-Neonatal Neuroimaging and Developmental Science Center at Boston Children’s Hospital. “A little is completely safe and healthy. But too much can burn.”
Now, I’m not talking about things like interventional radiology, where specialists use CT scans or MRIs to guide a procedure in real-time. Nor am I talking about nuclear medicine, which helps doctors look for signs of activity in cells or tissues that could signal the onset of disease. Neither field uses radiation or other imaging methods to directly treat illness, but rather to guide treatment.
While radiation is probably the most familiar example of this kind of technological double-dipping, we see the same thing with lasers. “At low power, lasers can be used to monitor all kinds of things,” says Grant, who’s working on ways to use near-infrared lasers to screen for brain injury in newborns. “But at a higher power, lasers can cauterize tissue, a common practice in operating rooms.” They’re also useful for eliminating abnormal blood vessels in vascular malformations and anomalies, for some skin or eye conditions and sometimes even for concussions (not to mention Lasik surgery and tattoo removal, too).
It’s the same story with ultrasound, a technology based on sound waves that’s widely used to monitor babies in the womb and to look for signs of disease in children. “There are therapies used in adult medicine based on focused ultrasound,” Grant explains. “Certain muscle conditions or growths can be treated with high-powered ultrasound devices that heat up the tissues in a targeted area.”
Even MRI machines may eventually be used to treat instead of just to image. Pierre Dupont, PhD, Boston Children’s chief of Pediatric Cardiac Bioengineering, is trying to harness the magnetic field produced by an MRI machine to power robots that could “travel through the body to perform highly targeted therapies or reside inside the body as adjustable prosthetic devices.” A post on our sister blog Vectorexplains:
That might include ball-bearing-sized robots that could be steered through the cerebrospinal fluid or the urinary system to deliver drugs or stem cells. Or implantable devices that could be adjusted to regulate blood flow in the heart. Or implants for children that could be gradually enlarged as they grow, preventing the need for repeat operations to place larger implants.
So where is the line drawn between using a technology for imaging versus for treatment? According to Grant, it’s all in the safety standards and infrastructure. “You need to have guidelines and boundaries for the power you use to image and the power you use to treat,” she says. “These are sophisticated machines, and we have to make sure of two things. First that we’re using them as we should, and second that we have the infrastructure available to make sure that they’re properly tuned and maintained. You’re only as good as your camera.
“This is why for x-rays and CT scans the Image Gently® guidelines exist, and why pediatric hospitals try to keep radiation doses as low as possible when scanning children,” Grant continues. “We don’t completely understand where the absolute threshold is when it comes to the tissue effects of radiation, but we recognize and understand the risks. That’s why we make sure that all our imaging hardware and software is maintained within the highest standards of excellence and operated well within the FDA guidelines for imaging children.”
To learn more about what our radiologists do to make imaging safe for children and how imaging children is different from imaging adults, check out the Boston Children’s Hospital Department of Radiology.