Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
SSINS No.: 6820
OMB No.: 3150-0012
IEB 86-04
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
OCTOBER 29, 1986
IE BULLETIN NO. 86-04: DEFECTIVE TELETHERAPY TIMER THAT MAY NOT TERMINATE
TREATMENT DOSE
Addressees:
All NRC licensees authorized to use cobalt-60 teletherapy units.
Purpose:
The purposes of this bulletin are (1) to inform NRC teletherapy licensees of
an identified problem with Picker/AMS teletherapy units that have Sodeco
Type RP-112E treatment timers, (2) to request that licensees affected by the
problem immediately provide appropriate instruction and training to
teletherapy machine operators on how to recognize the problem if it occurs
and take appropriate mitigating actions, (3) to request that licensees
notify the NRC of the existence of the problem at their facility, and (4) to
request that licensees inform the NRC of the measures taken to correct the
defective teletherapy treatment timer problem that is identified as a result
of this bulletin.
Description of Circumstances:
The NRC has recently received information revealing that the Sodeco Model
RP-112E teletherapy timer may not function properly. Operational malfunction
of the timer could result in radiation misadministrations to patients and
possible excessive radiation exposures to teletherapy unit operators.
In June 1984, Picker International, the predecessor company to Advanced
Medical Systems (AMS) decided to discontinue the sales and installation of
Sodeco Model RP-112E teletherapy timers. Those timers were replacements for
the obsolete (Liebel-Florshiem) timers in use at that time. The Sodeco
replacement timer is a 5-digit countdown counter registering in
one-hundredths of a minute (0.6 sec). The maximum treatment time available
on this timer is 999.99 minutes. Treatment time is selected by pushing and
holding the black reset pushbutton and then pressing the five white digit
selector pushbuttons, which organizes the row of digits sequentially until
the appropriate number is registered on the timer.
The specific problems which have been identified with malfunction of the
Sodeco timers include:
8610290161
.
IEB 86-04
October 29, 1986
Page 2 of 3
1. When any number (including 000.00) is registered, the timer control
switch will be closed, thus allowing treatment to be started by the
operator using the key switch. When the timer is manually reset to
000.00, activating the key switch will cause the source to come on.
Therefore, it is not recommended that this timer be reset to 000.00,
but rather to 000.01. At this setting, should exposure be inadvertently
begun, the normal timer-out sequence will reset almost immediately and
terminate the exposure.
2. The Sodeco timer failed to terminate a patient's treatment upon
reaching the termination set point of 000.00. Instead, the timer reset
to the maximum time setting of 999.99 and reinitiated a treatment time
countdown.
3. The Sodeco treatment timer was set with a beginning time between two
numbers (e.g., one of the settings was placed between numbers 4 and 5).
Treatment was initiated and the Sodeco timer failed to initiate a
countdown to the termination setpoint of 000.00.
Action Required of Teletherapy Licensees Having Picker International/Advance
Medical System Units Using Cobalt-60
1. Promptly determine whether or not your teletherapy unit has a Sodeco
timer as described in this bulletin. This may be accomplished by
reviewing your service records and by contacting a licensed service
organization.
2. If your unit has this Sodeco timer, or in the event positive
identification of the timer cannot be made, take action to have the
timer identified and replaced by an authorized licensed service
organization as soon as possible with an acceptable timer. If the unit
must be used before timer replacement, take the following actions:
a. Immediately instruct all operators of the unit (i.e.,
technologists), both orally and in writing, of the problems that
exist with this timer as identified in this bulletin.
b. Immediately post a warning and set of instructions at the
treatment timer control informing the operators of the procedures
to be followed (1) to ensure that the timer is not set in between
two numbers or on 000.00, and (2) to verify the elapsed treatment
time by a means other than the unit's treatment or elapsed timers.
c. Establish the necessary administrative controls to require
operators to verify the elapsed treatment time for each treatment
of humans by means other than the unit's treatment or elapsed
timer until the Sodeco timer is replaced.
3. Upon replacement of a Sodeco timer, and prior to use of the teletherapy
unit for treatment of humans, have an authorized licensed organization
test the replacement timer to ensure that it does not exhibit the three
problems identified in this bulletin.
.
IEB 86-04
October 29, 1986
Page 3 of 3
4. Within 15 days of receipt of this bulletin, provide (a) a written
report to the appropriate NRC regional office identifying whether or
not your Picker/AMS teletherapy unit contains a Sodeco type RP-112E
treatment timer, and, (b) if it does, identify the short-term
modifications to the emergency and operating procedures that have been
or are being implemented cts to assure safe treatment to patients
undergoing teletherapy treatments.
5. Within 45 days of receipt of this bulletin, if your Picker/AMS
teletherapy unit contains a Sodeco type RP-112E treatment timer,
provide a written report to the appropriate NRC regional office
describing the schedule for long-term resolution of the problems that
are identified as a result of this bulletin.
Should a licensee determine that any action requested by this bulletin
jeopardizes overall patient care and safety, the appropriate regional office
shall be immediately notified of that fact and provided with appropriate
justification for not implementing the requested action.
The written report shall be submitted to the appropriate Regional
Administrator under oath or affirmation under provisions of Section 182a,
Atomic Energy Act of 1954, as amended. Also, the original copy of the cover
letters and a copy of the reports shall be transmitted to the U. S. Nuclear
Regulatory Commission, Document Control Desk, Washington, D.C. 20555 for
reproduction and distribution.
This request for information was approved by the Office of Management and
Budget under blanket clearance number 3150-0012. Comments on burden and
duplication may be directed to the Office of Management and Budget, Reports
Management, Room 3208, New Executive Office Building, Washington, D.C.
20503.
If you have questions regarding this matter, please contact the Regional
Administrator of the appropriate NRC regional office or one of the technical
contacts listed below.
James M. Taylor, Director
Office of Inspection and Enforcement
Technical Contacts: Steve Baggett, NMSS
(301) 427-9005
Jack R. Metzger, IE
(301) 492-4947
Attachment: List of Recently Issued IE Bulletins
