United States Nuclear Regulatory Commission - Protecting People and the Environment

Bulletin 86-04: Defective Teletherapy Timer That May Not Terminate Treatment Dose

                                                       SSINS No.: 6820  
                                                       OMB No.: 3150-0012  
                                                       IEB 86-04  

                                UNITED STATES
                           WASHINGTON, D.C. 20555

                              OCTOBER 29, 1986

                         TREATMENT DOSE 


All NRC licensees authorized to use cobalt-60 teletherapy units. 


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: 


                                                         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 

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 

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. 

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
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