In regard to Part 21.21 Notification of failure to comply or existence of a defect and its evaluation, [the licensee notified] the NRC of a defect that was detected on the Varian, Mammosource unit, Gammamed Plus (M1), ID#H64E168.
The defect noted was the following:
A daily check is performed to verify when the source guide tube is disconnected from the unit head, the source will not extend. This test is performed as recommended on p. 73 of the ESTRO Booklet No.8, ' A Practical Guide to Quality Control of Brachytherapy Equipment'. Disconnecting the tube (i.e. the lock that connects the source guide tube to the turret of the Mammosource) the dummy wire or the source wire should have been prevented from extending out. If the disconnect is within 2 mm of being connected the wire does extend out. This was documented on a check film using the Mick PerinaDoc phantom. As recommended in the Varian GammaMed HDR User Manual, P. 6-20, Varian BrachTherapy service was called.
Notification:
Varian Corp. was notified of this problem on 1/30/08 and a service engineer will be sent to the site to adjust the light sensor that communicates whether the source guide tube is connected. We are continuing treatment with two independent physicists verifying before treatment that the source guide tube is connected properly and securely.
- * * RETRACTION FROM WISHKO TO HUFFMAN VIA E-MAIL AT 1431 EDT ON 3/13/08 * * *
Verbal communication with an engineer from Varian Corporation stated that when the source guide tube is disconnected within 2 mm from the turret of the Mammosource, the source can extend. Since this is a design feature and accepted by Varian Corporation, I wish to withdraw my report of notification on a discovered defect.
R1DO (Lorson) and
FSME (Wastler) notified.