United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 88-93: Teletherapy Events

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

                                December 2, 1988


Information Notice No. 88-93:  TELETHERAPY EVENTS 


Addressees: 

All NRC medical licensees. 

Purpose: 

This notice is intended to alert recipients to the circumstances leading to 
two recent teletherapy events and to emphasize the importance of the correct 
use of computerized treatment-planning.  It is expected that licensees will 
review this information for applicability to their programs, distribute this 
notice to those responsible for radiation safety, and consider actions, if 
appropriate, to preclude a similar situation from occurring at their 
facilities.  However, suggestions contained in this notice do not constitute 
any new NRC requirements, and no written response is required. 

Description of Circumstances: 

In March 1987, following a source exchange for a cobalt-60 teletherapy unit at 
a hospital in an Agreement State, the higher activity of the new source was 
not properly accounted for in the computerized treatment-planning system.  In 
particular, the computer program related to the use of beam trimmers was not 
updated because the beam trimmers were not being used by the licensee at the 
time of source exchange.  At a later date, the licensee began using beam 
trimmers again and based its treatment planning calculations on the incorrect 
old source output.  Because the licensee failed to update the program with the 
new source output, 33 patients received doses 75 percent in excess of the 
prescribed doses.  

In a second case, in a different Agreement State, teletherapy events occurred 
at three different hospitals.  Each of these hospitals used a different 
treatment-planning computer system.  A consulting physicist who was working at 
all three of the hospitals made random errors when using the programs.  The 
errors made indicated a misunderstanding of the computer parameter definitions 
and the limitations of the different treatment-planning systems.









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                                                            December 2, 1988 
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Discussion: 

All medical licensees are reminded of the importance of making accurate 
therapy-dose calculations, including computer-assisted calculations.  This is 
particularly important on occasions when the operating characteristics of the 
equipment might have been modified, such as after servicing or a source 
exchange.  Licensees should consider methods to ensure that only updated 
programs and data files are used in treatment planning.  In addition, 
licensees should consider steps to ensure that individuals using treatment-
planning computer systems are properly trained in the use and limitations of 
those systems.  

No written response is required by this information notice.  If you have any 
questions about this matter, please contact the appropriate NRC regional 
office or this office.  




                                        Richard E. Cunningham, Director 
                                        Division of Industrial and 
                                          Medical Nuclear Safety 
                                        Office of Nuclear Material Safety 
                                          and Safeguards 


Technical Contacts: J. R. Metzger, NMSS 
                    (301) 492-3424 

                    J. McGrath, Region I 
                    (215) 377-5216 

Attachment:    List of Recently Issued NRC Information Notices 
.                                                            Attachment 
                                                            IN 88-93 
                                                            December 2, 1988 
                                                            Page 1 of 1

                             LIST OF RECENTLY ISSUED
                             NRC INFORMATION NOTICES
_____________________________________________________________________________
Information                                  Date of 
Notice No._____Subject_______________________Issuance_______Issued to________

88-92          Potential for Spent Fuel      11/22/88       All holders of OLs
               Pool Draindown                               or CPs for nuclear
                                                            power reactors. 

88-91          Improper Administration       11/22/88       All holders of OLs
               and Control of                               or CPs for nuclear
               Psychological Tests                          power reactors and
                                                            all fuel cycle 
                                                            facility licensees 
                                                            who possess, use, 
                                                            import, export, or 
                                                            transport formula 
                                                            quantities of 
                                                            strategic special 
                                                            nuclear material. 

88-90          Unauthorized Removal of       11/22/88       All NRC licensees 
               Industrial Nuclear Gauges                    authorized to 
                                                            possess, use, 
                                                            manufacture, or 
                                                            distribute 
                                                            industrial nuclear 
                                                            gauges. 

88-89          Degradation of Kapton         11/21/88       All holders of OLs 
               Electrical Insulation                        or CPs for nuclear
                                                            power reactors. 

88-88          Degradation of Westinghouse   11/16/88       All holders of OLs
               ARD Relays                                   or CPs for nuclear
                                                            power reactors. 

88-87          Pump Wear and Foreign         11/16/88       All holders of OLs
               Objects in Plant Piping                      or CPs for nuclear
               Systems                                      power reactors. 

86-106,        Feedwater Line Break          11/10/88       All holders of OLs
Supp. 3                                                     or CPs for nuclear
                                                            power reactors. 

88-86          Operating with Multiple       10/21/88       All holders of OLs
               Grounds in Direct Current                    or CPs for nuclear
               Distribution Systems                         power reactors. 
_____________________________________________________________________________
OL = Operating License
CP = Construction Permit 
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