When physicist Stephen Adler, Ph.D., joined the Frederick National Laboratory for Cancer Research (FNL), he quickly observed a gap in the tools to measure radiation doses in preclinical research.  

Precise radiation doses are critical for many preclinical experiments with small animal models—doses which are typically in the few microcuries (µCi) range. However, when Adler tested the available measurement instruments, he realized the existing tools were less than optimal in this important range. Available dose calibrators typically measure at 10–1000 µCi and higher.  

Meanwhile, well counters, devices used to measure smaller amounts of radioactivity, are best suited for measurements of doses less than 1 µCi. This creates a gap in the 1–10 µCi range, a critical range for bio-distribution and cell binding studies, cell labeling, and other pre-clinical research activities. 

“There was a big problem trying to measure radioactivity at the actual levels they were using in preclinical research,” said Adler, who specializes in positron emission tomography. “There was this sort of dark spot, this unknown activity range, which neither instrument was very good at measuring.”  

The microbiologists conducting the studies were aware of this challenge and had developed techniques to compensate. But Adler was not satisfied with working around the problem; he wanted to solve it.  

“I came from this completely different field,” he said, referring to his time as an experimental physicist at the Brookhaven National Laboratory nuclear collider facility, which he called a “high-end energy physics world where we spend all our time making measurements. If we can’t make the measurement, we build an instrument to do what we need to do.”  

Building a new dose calibrator 

Adler set out to develop a micro-dose calibrator prototype to effectively illuminate this dark spot. To create his prototype, he took advantage of two opportunities for independent funding available to FNL scientists. First, he applied to the FNL’s Laboratory-Directed Exploratory Research program, which typically funds five to six innovative projects each year through a rigorous scientific review process. The program allows scientists to conduct research they believe is important to the FNL’s mission but is outside the scope of their normal work. His application was accepted and along the way, his micro-dose calibrator—which at the time was just a 3D printed model—captured the attention of the National Cancer Institute Invention Development Program. This program provides resources to accelerate the development timeline of promising inventions.  

With the support of both programs, Adler purchased supplies, wrote the software and constructed a working prototype. His invention went beyond his initial goal of filling the 1–10 µCi gap; it can measure radioactivity doses between 0.1–100 µCi with 99% accuracy.  

This protype is now widely used in a small animal laboratory. 

“It’s become somewhat of an important instrument, and if I took it away, there would be some [principal investigators] that would be yelling at me,” Adler joked. “I’d like to move it to another laboratory, but they seriously will be mad at me if I take it away from them.” 

Lucky for the investigators he built a second prototype to be deployed at a partner’s laboratory for further evaluation. Two companies are now interested in testing the device.  

Adler’s goal is to commercialize his device and get it into more laboratories where it can help improve pre-clinical research. The micro-dose calibrator is currently available for collaborative co-development or licensing. 

“It was built for the right reasons,” he said. “It really is an important instrument.”