United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 97-64: Potential Problems Associated with Loss of Electrical Power in Certain Teletherapy Units

                                 UNITED STATES
                         NUCLEAR REGULATORY COMMISSION
               OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
                            WASHINGTON, D.C.  20555

                                August 13, 1997


NRC INFORMATION NOTICE 97-64:  POTENTIAL PROBLEMS ASSOCIATED WITH LOSS         
                               OF ELECTRICAL POWER IN CERTAIN TELETHERAPY      
                               UNITS

Addressees

All U.S. Nuclear Regulatory Commission medical teletherapy licensees.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert addressees to a potential problem associated with loss of
electrical power in the Theratron 1000 teletherapy unit manufactured by
Theratronics International, Limited.  It is expected that recipients will
review the information for applicability to their facilities and consider
actions, as appropriate, to avoid similar problems.  However, suggestions
contained in this information notice are not NRC requirements; therefore, 
no specific action or written response is required.

Description of Circumstances

An Agreement State licensee notified the State authorities that a
misadministration had occurred during a teletherapy treatment.  Specifically,
while a patient was being treated, a thunderstorm resulted in a loss of
electrical power twice during the treatment period.  A hospital technologist
reset the machine both times to allow treatment continuation.  When the
treatment ended, the patient commented that the wrong site may have been
treated.  The technologist then noticed that the light field was not aligned
to the intended treatment site.

The hospital's Radiation Safety Officer and technologist were able to recreate
the problem only when the technologist was lying on the table in the position
that was occupied by the patient being treated and power was interrupted.  The
table subsequently moved approximately 20 centimeters (8 inches) in the
longitudinal direction.  The licensee then calculated that the patient 
received approximately 130 rads to the wrong treatment site.  The hospital
notified the manufacturer, Theratronics, of the event.  After an
investigation, the manufacturer concluded that the licensee had not operated
the teletherapy unit in accordance with the operating instructions.  The
manufacturer, however, noted the problem and flagged the operating
instructions for possible improvement during the next general revision of the
operator's manual.


9708070081.                                                            
                                                            IN 97-64
                                                            August 13, 1997
                                                            Page 2 of 2


Discussion

All licensees are reminded of the importance of ensuring the safe performance
of licensed activities in accordance with NRC requirements, the requirements
of their licenses, and the instructions in the manufacturer's operator�s
manual.  Section 4.7 of the operator�s manual discusses actions that must be
taken if there is a loss of electrical power.  These actions include removing
the patient from the treatment room and realigning before resuming treatment. 
In addition, Section 4.7 contains a warning that states:

      [i]f Table 23T is equipped with the �free float� option, when the power
      is off, the lateral and longitudinal motions will be free.  Take care to
      prevent injury when unloading they should
clearly understand the manufacturer operator�s manual.  Additionally, in cases
where questions or problems arise concerning unit use, users should contact
the manufacturer and should remember the potential for causing a significant
radil device user facilities are now
subject to mandatory Food and Drug Administration (FDA) adverse event
reporting requirements for medical devices.  Information concerning FDA�s
mandatory reporting requirements can be obtained by contacting the Center for
Devices and Radiological Health, Office of Surveillance and Biometrics,
Division of Surveillance Systems at (301) 594-2735.  Since the FDA mandatory
reporting requirements may not be applicable to all medical device events, FDA
also depends on information voluntarily provided by device users because they
are often the first to recognize medical device related hazards.  Any concerns
that licensees may have pertaining to the safety or quality problems
associated with medical devices can be voluntarily reported to the FDA by
calling MedWatch at 1-800-FDA-1088.  Voluntary reports can be submitted
anonymously.

This information notice requires no specific action or written response.  If
you have any questions about the information in this notice, please contact
the technical contact listed below.


                                                signed by F.C. Combs for

                                          Donald A. Cool, Director
                                          Division of Industrial and 
                                            Medical Nuclear Safety
                                          Office of Nuclear Material Safety
                                              and Safeguards

Technical contact:  Nader Mamish, NMSS
                    301-415-6316
                    E-Mail: nlm@nrc.gov   Coordinated with Theratronics & FDA
Page Last Reviewed/Updated Tuesday, December 03, 2013