An ongoing shortage of oxygen-18 has shown few signs of abatingthis year despite increased production from the only U.S. companymarketing the isotope. Oxygen-18 is the raw material for a widelyused positron emission tomography radiotracer. There could
An ongoing shortage of oxygen-18 has shown few signs of abatingthis year despite increased production from the only U.S. companymarketing the isotope. Oxygen-18 is the raw material for a widelyused positron emission tomography radiotracer. There could belight at the end of the tunnel for PET users, however, as a secondAmerican firm is producing test runs of oxygen-18 with the goalof becoming a major supplier.
Cambridge Isotope Laboratories reported last month that itis making oxygen-18-enriched water at an isotope separation plantin Xenia, OH. The Woburn, MA-based company is responding to achronic shortage of oxygen-18, according to president Joel Bradley.
"We found a big demand in the marketplace for oxygen-18,primarily from PET users," Bradley said. "The availabilityand dependability of current supplies were causing a lot of aggravationin the PET market."
When bombarded with protons in a cyclotron, oxygen-18-enrichedwater is converted to fluorine-18, the raw material for 18-fluorodeoxyglucose.FDG-18 is used in over 90% of clinical PET studies.
PET users have been suffering from a shortage of oxygen-18for the past several years as PET usage has increased and severalproduction facilities have been shut down (SCAN 10/21/92). IfMedicare coverage of PET is approved this year by the Health CareFinancing Administration, increased PET usage could strain supplieseven further.
Isotec of Miamisburg, OH, the only domestic supplier of oxygen-18,has had difficulty meeting demand for the isotope despite bringinga third isotope plant on line in January.
PET clinicians say Isotec's added capacity has not eased theshortage, which has PET facilities waiting up to nine months foroxygen-18 shipments.
"I haven't seen any improvement in our ability to getoxygen-18 water," said Dr. R. Edward Coleman, director ofnuclear medicine at Duke University Medical Center in Durham,NC. "I don't think that (Isotec) has eased the problem atall over the past year."
Enter Cambridge Isotope Laboratories, which manufactures stableisotopes such as carbon-13 and nitrogen-15 at its plant in Ohio.The shortage is proof that there is room for more than one playerin the oxygen-18 market, according to Bradley.
With minor modifications to its facility, CIL has been ableto produce oxygen-18 with the same cryogenic distillation columnused to make carbon-13. CIL has produced several kilograms ofwater that is 65% to 70% enriched with oxygen-18, Bradley said.
CIL's water is significantly less enriched than Isotec's, whichhas an enrichment level of at least 97%, according to Isotec presidentVincent L. Avona.
Could the lower enrichment level have an impact on PET practices?Most PET experts say that while fluorine-18 can be produced fromwater with an enrichment level of 65%, the amount of fluorine-18created during the process is lower. A typical cyclotron run withless-enriched water would also take longer to produce the isotopethan one using highly enriched water, which could translate intofewer PET studies performed each day.
PET centers that have received CIL's water have not had problemswith it, according to Bradley.
CIL is sounding out the oxygen-18 market and has not yet begunfull-scale production. The size of the company's investment inproducing oxygen-18 is small, but that could change dependingon feedback from PET users.
Isotec also plans to expand its production capacity. The companyshould have a fourth distillation column completed by the endof the year and expects to build a fifth in 1994, according toAvona. Until then, life will continue to be hand-to-mouth foroxygen-18 users.
"There's going to be a shortage for the next year, butafter that we have column number five on the drawing board,"Avona said. "Two years from now there is going to be moreoxygen-18 water than anybody will want."