Optical Guidance Platform, version 2.6 and 2.6.1; Reference/FSCA Identifier: CP-03899; Product is manufactured and distributed by Varian Medical Systems Inc., Palo Alto, CA Optical Guidance Platform is for use with a charged particle accelerator to perform precise positioning of treatment target for stereotactic radiosurgery or radiotherapy treatments on cranial or extracranial lesions.

The optical guidance platform may not be properly enforcing a 24 hour time limit between optical camera recalibrations.

The firm, Varian, sent an "URGENT MEDICAL DEVICE CORRECTION-URGENT FIELD SAFETY NOTICE" letter dated March 3, 2011 to its customers. The letter described the product, problem and actions to be taken. The customers were instructed to immediately check the Calibration timeout on their optical guidance platform. If this exceeds 24 hour, please set the factory default of 16 hours to ensure that the camera will be calibrated daily. The instructions are located in the document. The customers were also instructed to download the most recent version of the Optical Guidance Platform Instructions for Use at www.MyVarian.com or request a copy from their local Varian Customer Support District or Regional Manager. In addition, the customers were instructed to advise the appropriate personnel working in their radiotherapy department of the content of this letter. Varian is preparing a software patch which will be applied to affected units to correct this issue. If you require further clarification, please feel free to contact your local Varian Customer Support District or Regional Manager; USA and Canada -1888-VARIAN5 (888-827-4265) or Europe- +41 41 749 8844.