Martinos Center prepares 200th PET radiotracer injection of 2014

December 31, 2014

 

The Martinos Center recently prepared its 200th human dose of the year for positron emission tomography (PET) scans. This would be an accomplishment for any PET program—the preparations are lengthy and involved and require no small amount of skill and patience—but it is especially notable for one so young.

PET imaging uses radiotracers injected into a subject or patient to trace particular biological pathways—in disease, for example. But because of the very short half lives of the doses (about 20 minutes for Carbon-11, the most-used isotope in the Center), the radiotracers are generally produced onsite and on demand and administered to the subject or patient soon after.

Part of the challenge in this is the preparation time. Setup takes about four hours in the morning and each synthesis about two hours. Ultimately, said Jacob Hooker, the director of the Hooker Research Group, who oversees production of the radiotracers, they have only a few minutes wiggle room in timing for each and every PET scan, "which is a logistical feat."

Indeed, this is unique in the pharmaceutical industry. Most manufactured products have considerably longer enough shelf lives and thus none of the same constraints.

The very short half lives of the radiotracers also means there's no room for error. With other pharmaceuticals, manufacturers would have an opportunity to recall the product if any issues arise before it reaches the public. “We do not have this luxury,” said the Hooker Research Group’s Judit Sore. “We must be super-precise and focused on what we do so no mistakes are made in the first place.”

Sore, the PET radiotracer production manager with the group, is responsible for all aspects of production of the radiotracers in the PET program. In all, they prepare 13 different tracers for human use. It’s her job to make sure everything gets done efficiently and in a timely manner.

While she and her colleagues in the radiotracer lab—Kari Phan and Garima Gautam—produce PET injections primarily for research purposes, they must still adhere to all regulatory guidelines as if they were making them for clinical and diagnostic applications. These include guidelines set by the Food and Drug Administration, the Massachusetts State Board of Pharmacy, the Nuclear Regulatory Commission, and more. Even the smallest of lapses could lead to an audit. Immediate shutdowns of PET centers are not unheard of.

All of which makes the recent milestone the more impressive. Not only has the group increased the number of human injections over last year, it has done so while keeping on top of the documentation required for each dose, which has almost doubled in the same time. And all of this without increasing staff.

In a stroke of happy coincidence, the 200th human dose was an injection of [11C]Martinostat. The Hooker Research Group introduced this PET radiotracer just a few months ago, to begin to explore an important family of proteins in the living human brain, and only recently started using it in test subjects.