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We have just learned that several years ago, some versions of the software used with the Gamma Knife equipment have been recalled due to errors (bugs). This software, called "Leksell GammaPlan", is intended to be used for planning the dosimetry of treatments;  as a result of these bugs, some patients could receive a dose higher or lower than prescribed:

• Recall #Z-118-9:  June 1997, Versions 4.01-4.11
  Reason: An error in the plug command which caused the dose planning software GammaPlan to give too long treatment times, meaning that the patient receives a higher dose than prescribed.
  
• Recall #Z-119-9: July 1998, Version 3.01
  Reason: Instead of using the 50% line, the default dose setting was used resulting in the administration of 10Gy rather than 22Gy resulting in underdose.
  Description:  There was a case where the physicist did not enter a dose when planning a treatment and GammaPlan's default dose of 10 Gy was used. Despite the fact that the protocol printed said 10 GY and was reviewed and signed off without looking at the dose. Thus the patient was underdosed. Elekta has changed GammaPlans to include additional verification if the user does not set the dose and wants to use the default dose.
  
• Recall #Z-120-9: July 1996, Version 3.0
  Reason: A calculation error in the dose planning system may, under unusual circumstances, result in the miscalculation of the distance form (sic) the skull boundary to the intended target, resulting in a dose lower than prescribed.

GK Centers are now using Gamma Plan 5.0 and forward, so this represents versions that should no longer be in use.  However, we urge anyone considering GK treatment to ask specifically whether the version of software on the GK machines they will be treated with is not listed in the recall.  To see these recalls for yourself, please go to http://www.fda.gov/bbs/topics/ENFORCE/ENF00563.html   then search for the word "gamma" or just scroll about two-thirds the way down.

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Last Edited: Wednesday, October 30, 2002