由 Diana Bradley
, Staff Writer | November 13, 2012
From the October 2012 issue of HealthCare Business News magazine
Although tungsten is commonly used in nuclear medicine and is acceptable from a physics perspective, its usage is still just a fraction of lead’s, says Bogutski. There are three reasons for this: cost, availability and material versatility.
For example, Biodex, which has been producing nuclear medicine shielding since 1949, uses solid tungsten and machines it into necessary shapes for effective syringe shielding for nuclear medicine. However, there are still some cases where lead is more appropriate than tungsten.
“With larger shields – like large PET shielding -- Biodex still uses lead due to cost,” says Robert Ranieri
, Biodex’s VP of sales. “But we use lead encased in steel or stainless steel.” Typically, the cost of lead is $1.50 to $2 per pound, while tungsten materials and plastic compounds can run upward of $50 per pound. “Often, in a nuclear medicine setting, thousands of pounds will be required,” says Bogutski. “The dollar difference adds up quickly.”
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Unfortunately, the cost of tungsten has continued to rise in recent years. This increase is due largely to the fact that 70 to 85 percent of the world’s tungsten is imported from China, according to Sery. However, this may soon change.
“There are a number of companies opening up tungsten mines in the United States as well as in Canada to offset some of the high costs coming out of the Far East,” Wolff says. “But for the time being, if medical companies can get by with lead, they are certainly going to do that because it’s less expensive than any of our compounds.”
However, companies like Thogus have developed methods to get over this economic hurdle.
“If you have a part that’s traditionally been made out of lead and it has a lot of secondary operations -- let’s say it needs to be machined, coated, painted or protected from anybody touching it -- more often than not, we can come up with an economic justification for our materials, because we eliminate secondary operations by injection molding a part,” says Wolff.
In addition, lead has a single specific gravity – 11 grams per cubic centimeter. The advantage of using a material like tungsten is that the density can be custom compounded for a specific application.
“We can tailor make the mixture; we have lower densities that are available all the way down to 2.7 grams per cubic centimeter, which gives us the opportunity to customize for the application,” says Wolff.
As density is reduced, so is the amount of tungsten filler. The result: lower costs.
“The beauty of tungsten is you don’t need expensive molds,” explains Sery.