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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. IN 88-93
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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