Toshiba rolls out liquid-metal CT tube for quick cooling after helical studies

HeliCool to ship on compact Xpress/GX scanners

Toshiba America Medical Systems of Tustin, CA, plans to beginshipments in March of a new CT x-ray tube that uses liquid-metaltechnology to improve the dissipation of heat generated duringhelical exams. The new tube, called HeliCool, will be availableon the company's mid-range Xpress/GX scanner.

In developing HeliCool, Toshiba engineers dispensed with the ballbearings around which a conventional CT x-ray tube's anode rotates.The high heat associated with x-ray generation in an anode cancause bearings to wear prematurely or even weld together if toomuch heat dissipates down the shaft around which the anode rotates.

The HeliCool tube replaces the ball bearings with a bigger shaftthat uses liquid metal rather than bearings as a lubrication medium,according to Scott Eaton, product manager. Because the lubricatingmaterial is metal, it is a good conductor of heat, Eaton said.Liquid-metal technology is also used on Philips' MRC tube line.

Toshiba has not released HeliCool's heat rating, but the tubedissipates heat three times as fast as Toshiba's top-of-the-line6.5-million-heat-unit (MHU) tube. At 50% heat loading, the 6.5-MHUtube's cooling rate is 66 KHU/min, while HeliCool's cooling rateis 188 KHU/min. The maximum wait time for cooling after a typicalhelical chest scan is five minutes, which represents a 50% improvementover conventional tubes, according to the company.

Toshiba developed the tube for Xpress/GX because the compact scanneris too small to be fitted with 6.5-MHU tubes, which have largeranodes, according to Eaton. Eaton declined to state whether Toshibaplans to develop liquid-metal tubes for other scanners in itsCT product line.

When HeliCool begins shipping next month, it will be availableas an upgrade to Xpress/GX scanners in the field at a list priceof $90,000. It is available on new Xpress/GX scanners as an option,costing $30,000 more than a standard 3.5-MHU tube.