Los Alamos-developed technology may help see the way to safer X-rays
Most of us have to get X-rayed from time to time, whether it’s for a checkup at the dentist, a broken bone, or soft tissue imaging for things like mammograms or checking for lung diseases.
Apart from medical examinations, X-ray diagnostic tools are widely used in research institutions and labs for nondestructive probes. Modern X-rays require a much lower dose of radiation than they once did, but the X-ray technician is still likely to drape you in a lead apron to prevent inadvertent exposure of other areas of your body.
A new X-ray detector prototype is on the brink of revolutionizing medical imaging, potentially reducing the need for (or at least the weight of ) a lead apron. The advance could dramatically decrease medical radiation exposure, while also boosting resolution in security scanners and research applications, thanks to a novel type of electronics being developed at Los Alamos National Laboratory, in coordination with Argonne National
Laboratory researchers.
The X-ray detector is one application of devices that rely on crystals that incorporate the mineral perovskite, instead of the silicon in most conventional detectors. The Los Alamos prototypes offer a hundred times more sensitivity than conventional silicon-based detectors. And unlike their silicon cousins, the perovskite versions don’t require an outside power source — instead the energy of the X-rays themselves is enough to run the detectors.
High-sensitivity perovskite detectors will enable dental and medical images that require a tiny fraction of the exposure that accompanies conventional
X-ray imaging. Reduced exposure decreases risks for patients and medical staff alike.
Because perovskite is rich in heavy elements, such as lead and iodine, X-rays that easily pass through silicon undetected are more readily absorbed, and detected, in perovskite. This allows perovskite detectors to be much thinner than conventional detectors.
Slim perovskite detectors offer increased resolution for highly detailed images. In effect, thick silicon detectors are comparable to peering through a thick, frosted window, in contrast to perovskite versions that are tantamount to gazing through a thin, clear sheet of glass. The clearer view will lead to improved medical evaluations and diagnoses. Those fuzzy X-ray images that you may be used to will be replaced with crisp photos that are easier for radiologists, and you, to understand.
Higher resolution is just one benefit of perovskite X-ray detectors. They will also be much cheaper and easier to manufacture. Silicon-based devices are made in clean-room facilities that require vacuum pumps and expensive machines for drawing circuitry and depositing metals, insulators, and other materials. Perovskite devices are produced by depositing liquids on a wide variety of surfaces. In effect, they could be made with something resembling an inkjet printer, in much larger sizes than is possible with silicon, and potentially on flexible substrates that can be custom shaped as needed.
Beyond medical applications, ink-jet printed perovskite X-ray detectors could provide security scanning in airports and shipping terminals, and could even be used for telescopes that scan the sky for X-ray emissions from stars and galaxies. Telescopes that currently use silicon detectors that cost hundreds of thousands of dollars would benefit from cheaper, higher-resolution perovskite upgrades.
Researchers have just begun to scratch the surface of perovskite applications. In addition to X-rays, they offer one of the most promising routes to high-performance solar cells, gamma-ray detectors for astrophysics observations, lasers, and LEDs. All of which will likely be cheaper to manufacture and more versatile because of the variety of shapes and sizes we will be able to produce them in.
Just where you may run across perovskite technology in the future remains to be seen, but safer, clearer medical X-rays may be one of the first.
Wanyi Nie is a research scientist fellow in the Center of Integrated Nanotechnology at Los Alamos National Laboratory.