PETNET

This month I am at PETNET in Winston-Salem NC. It is a nuclear pharmacy that produces PET, or positron emission tomography, materials. The product they produce is called F18-FDG which is a compound similar to glucose with a radioactive fluoride molecule on it.


Glucose is a naturally occuring sugar in our body that produces the fuel for metabolism processes in the body. As cells go about their daily lives, they use glucose for energy to make and breakdown compounds throughout their day. The busier the cells are, the more glucose they use. How does that relate to FDG? Well, cancer cells use a LOT of energy and since FDG looks like glucose, they snag all of it they can. FDG is not the same as glucose, however, so it just gets trapped in the cells instead of getting used, so we can take a picture of it. In essence, PET nuclear medicine is used to identify and stage cancer (for the most part), and traditional SPECT nuclear medicine is used for diagnostic testing to see if organs are functioning properly.


PET has a higher energy than the traditional technetium-based products, so exposure (and thus shielding) is higher. Instead of working in a regular IV hood with an L-block to protect my torso, PET doses are drawn up in an enclosed "hot box" with manipulator arms. The "pigs," lead or tungsten containers used to hold and shield doses for transport, are larger and so are the boxes used for transporting doses. An empty box weighs about 70 pounds!


Another difference between PET and traditional nuclear pharmacy is how we get our products. With technetium, we have a generator made of molybdenum that decays to Tc-99m that we used to make kits (the radioactive saline is added to vials of powder containing the drug and some other compounds necessary for the chemistry). In PET, we have a cyclotron that bombards O18-water (regular oxygen is O16) with protons to make F18. We physically make the radionuclide onsite. Once we have F18, we transfer it to a mini-cell that makes and purifies F18-FDg from scratch. PET labs are divided to have one area that is a manufacturer and one area that is the pharmacy (which also means more regulations!).


It has been pretty interesting so far to learn all the chemistry and the quality control procedures necessary to satisfy both pharmacy and manufacturing requirements. My preceptor has also been letting me draw and ship doses this week. Those manipulator arms are more difficult to work than I thought, and I've used mucles I never thought I would need for pharmacy! I still love nuclear, I think its fantastic. PET is growing and there are more products in the works, they just need more data before getting approved by the FDA. Its amazing to see how nuclear pharmacy has progressed from the 1970s and I can't wait to see how it will change throughout my career!!