In response to our current "Warning to MRI Owners and Operators" story, Clark R. Wilkins of JDI Solutions wrote:

"Mr. Gilk makes good points with respect to the facility issues, but does not seem to understand the nature of today's superconducting magnets. Our experience, though limited to Oxford magnets, is that boiloff rates rise to 3-5% per day after about 48 hours without power. This means a magnet that was recently filled with cryogens would last as long as 15 days or more without power before it would quench. As a rule of thumb, the owners who have Oxford magnets with coldheads should note their last known cryogen level and make a calculation based on a 5%/day boiloff rate. There are steps they could take to try to save their magnet such as bringing in a generator and ramping the magnet down, bringing in a specialist to try to soft quench the magnet through the power supply by operating the switch heaters with a portable current source, and last, and least desirable, quenching the magnet intentionally via the battery
backup. These techniques are useful in that they help reduce the likelihood of damage to the magnet in the case where most of the helium is gone when it quenches."


Tobias Gilk, author of "Warning to MRI Owners and Operators" answers:

"In a controlled environments with newer and well maintained, recently topped-off magnets, facilities might expect well over a week prior to a quench, but given the mix of magnets in the region, the fact that many may not have been well maintained or recently filled, and the likely environmental shocks from the hurricane, we believe that it is most appropriate to alert facilities and emergency response personnel to the imminent risk of quench."

"Mr. Wilkins' comment is absolutely correct and points out an oversight in the initial alert... That the risk of a quench (and the opportunity to prevent one) isn't limited to only the first several days after power loss. The time-window for the risk is, as Mr. Wilkins indicated, longer than suggested in our original bulletin."

Mr. Clark R. Wilkins responds to Mr. Tobias Gilk:

"Mr. Gilk continues a long trend of being a well-mannered and informed gentleman. I salute him for his graciousness and am in total agreement with all of his other points."

In response to last week's Letter from the Editor, "Tell Us About Your Favorite Charity," Suzanne L. Adams, CT (ASCP) wrote:

"The Vitamin Angels are one of my favorite charities. They are helping children in poverty all over the world. See their website at http://www.vitaminangels.com"

In response to last week's story about Paul Bauers being arresting on fraud charges, Mardy Evangelista wrote:

"It's good to hear that people like Paul Bauers getting cuaght for fraud. It only proves that the justice system is not sleeping and they are giving these people some sense into their empty brains. Good work!!!"

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