You may often wonder what atomic, nuclear, or particle physics has to do with modern medicine. The answer is, quite a lot. In fact, many of the technologies currently used in hospitals around the country owe their own existence to fundamental research in physics, from MRI, PET and CT scanners, to radiation therapy.
Recently, a new contrast agent obtained FDA approval for its use in both adults and children over six years old: hyperpolarized 129Xe gas (XENOVIEW). This contrast allows clinicians to visualize ventilation and gas exchange in the lungs in great details, something that traditional MRI alone, or other imaging modalities, cannot do.
The basic idea is simple. By aligning the nuclear spins of noble gases such as helium-3 or xenon-129, physicists create a “bright” gas that produces a strong MRI signal, similar to the signal produced by water molecules in a standard MRI scan. When a patient inhales this polarized gas, MRI can directly image the airspaces of the lungs, mapping ventilation, detecting obstructions, or revealing tiny regions of trapped air.
If you wonder, this technology didn’t come from a hospital or a biotech startup. It originated in nuclear physics laboratories, where researchers developed spin-polarized gases to serve as targets for scattering experiments to study the internal structure of atoms. A group of physics graduate students at Princeton realized that this same technique could revolutionize medical imaging, and later founded a company to build compact “polarizers” to produce hyperpolarized gas to be used as contrast agent for MRI.
Fast-forward to today, few weeks ago I was in a zoom meeting where a clinician described how this technology spared a young child from lung resection surgery. Hyperpolarized xenon helped them detect a small leak (< 1mm) of gas between a valve that had been previously placed and the lungs, changing the surgical plan and preserving the child’s lung.
The list of connections between Physics and Modern Medicine goes on and on. MRI itself is rooted in quantum mechanics, specifically in this mysterious property of elementary particles, the spin. Positron Emission Tomography (PET) relies on antimatter annihilation, a phenomenon first observed in particle physics. CT scanning evolved from mathematical algorithms used in X-ray crystallography. Even the pulse oximeter, which you can find almost in every hospital room, owes its function to optical absorption physics.
So next time you walk through a hospital, remember that behind every beep, image, and scan lies a century of physics research!
Fundamental physics experiments, often regarded as purely academic or only driven by the love of science, have and will continue to touch human lives in the most tangible ways.