Bulletin 92-02: Safety Concerns Relating to "End of Life" of Aging Theratronics Teletherapy Units

                                                            OMB No. 3150-0009
                                                            NRCB 92-02

                                 UNITED STATES
                         NUCLEAR REGULATORY COMMISSION
                            WASHINGTON, D.C.  20555

                                August 24, 1992



     For Action  - All Teletherapy Licensees

     For Information - None


This bulletin:  (1) notifies you about concerns related to the useful safe
life of older Theratronics International Limited (formerly AECL Medical)
teletherapy units; (2) requests that all action addressees take the
appropriate recommended actions; and (3) requires that all action addressees
provide the U.S. Nuclear Regulatory Commission with a report describing their
findings and actions taken and notify NRC when they have completed all actions
associated with this bulletin.

Description of Circumstances

Beginning with the discovery of crack(s) in the cast iron arms of a Theratron
80 (T80) teletherapy unit in 1983, Theratronics has issued three "User
Bulletins" to all consignees of Theratron 60's (T60's) and T80's.  These
bulletins all addressed the necessity of inspecting the arms in accordance
with a revised maintenance section of the unit's instruction manual.

In 1991, the Center for Devices and Radiological Health of the Food and Drug
Administration (FDA) became concerned about this possible safety issue and
inspected Theratronics, concentrating primarily on the cobalt therapy devices.
In addition to the problem with the cracked arms, the FDA inspection found
that the firm had other continuing problems with the T60 and T80 units.  These
problems include gantry rotation and timer malfunctions, stuck sources,
optical distance indicator errors, problems with bolts, pins, and screws, and
inadvertent raising of the patient couch without switch activation.

As a result of the problems uncovered during FDA inspections, Theratronics
voluntarily issued a user bulletin that was classified as a "Safety Alert" by
FDA in May 1991 (FDA # M-020/021-1).  This bulletin advised all T60 and T80
users of the potential for cracking in the arms of their units.  In addition,
as the result of the inspections Theratronics subsequently issued a number of
user bulletins affecting various firm products that were classified as
"Recalls" by FDA.  FDA has also placed in effect an "Import Alert" preventing
the importation of all of the firm's radiation therapy treatment and planning


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systems from Canada.  The latter action will remain in effect until the
company satisfies the FDA that the problems uncovered in the FDA's inspection
of the firm are corrected. 

After these actions, Theratronics issued two "User Bulletins" -- CUB-91-03NA,
dated June 5, 1991, and CUB-91-04NA, dated June 24, 1991 (Attachments 1 and
2).  The purpose of these bulletins was to inform users of the firm's
Theratron Junior, Eldorado A, Eldorado G, Eldorado Super G, Ceasatron E,
Eldorado 6 and Eldorado 8 (CUB-91-03NA) and users of its Theratron 60 and 80
(CUB-91-04NA) teletherapy units that, in the opinion of the manufacturer,
these units have exceeded their useful safe life and should be removed from
service, especially those units with cast iron components.  The manufacturer
also stated that spare parts were becoming increasingly difficult to provide
and, in some cases, were completely unavailable.  As of the issue date of the
respective bulletins, the manufacturer further stated that routine service,
service contracts, replacement sources, and accessories would no longer be
made available.  Further, spare parts would only be supplied on an "as
available" basis. 


The potential hazard to patients and employees from crushing injuries due to
catastrophic failure of the arm is obvious.  In 1987, a mechanical failure in
the drive unit of an aging Eldorado 6 unit resulted in a crushing fatality to
a patient.  Such failures could also expose, or leave exposed, the source.  In
such an event, significant exposures to the patient and/or employees could
readily occur, particularly if the failure rendered inoperable the normal
emergency source-retraction mechanisms.  A worst-case scenario -- an injured
individual trapped in the treatment room with an exposed source -- could lead
to a fatal overexposure. 

The broader safety issues related to the withdrawal of the manufacturer's
support for these units concern NRC.  This lack of support may lead to
incidents of deferred or improper maintenance at a time when service and
maintenance requirements are normally increasing as components age.  Improper
servicing, repair, or substitution of spare parts could readily produce device
failures resulting in overexposures to both patients and employees. 

The Theratronics International Limited teletherapy models affected by the
manufacturer's withdrawal of support are: 

     Theratron Junior
     Eldorado A
     Eldorado G
     Eldorado Super G
     Ceasatron E
     Eldorado 6
     Eldorado 8
     Theratron 60
     Theratron 80 and 80R

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In addition, the Theratron 60 and 80 models are subject to cracks developing
in the cast iron arm. 

Requested Actions

Those addressees possessing one or more of the affected models must submit the
information specified under "Reporting Requirements" within 60 days after 
receipt of this bulletin.  Those addressees who do not have one of the listed
models need only submit an abbreviated report listing the make(s) and model(s)
they possess, along with a statement that, based on make(s) and/or model(s),
they are exempt from the additional reporting requirements of this bulletin.

Reporting Requirements

Provide information on how you are going to handle the "end-of-useful-life"
issue and the maintenance and servicing issues related to the manufacturer's
withdrawal of support.  At a minimum, the following information should be
included in your report:

(1)  Make and model number of teletherapy unit

(2)  Date of manufacture (if known)

(3)  Serial number

(4)  Describe the present use of your teletherapy unit, (e.g., research,
     instrument calibration, routine clinical use, backup for an accelerator,
     etc).  If used for patient treatment, what is the average weekly patient
     workload and what alternative(s) are available to treat these patients if
     the unit had to be removed from service for an extended period of time  
     for service or replacement? 

(5)  If you possess one of the T60 or T80 units with a cast iron arm, describe
     your commitment to perform the special inspections per Theratronic's
     revised Survey and Inspection Procedure I 1024 G091G10 REV C. and your
     action(s) if stress cracking is discovered.

(6)  What has been the service record of your teletherapy units for the past
     five years?  List each failure, its cause, length of down time, and
     replacement components, if any, necessary to return the unit to service.

(7)  Is your teletherapy unit presently covered by a service contract and, if
     so, by whom?  What is the expiration date of the contract?  Do you expect
     to renew the contract and, if so, for what additional period of time?     
     What is covered by the contract?

(8)  Describe your facility's commitment to ensure the continued safe clinical
     use of these aging teletherapy units.  At a minimum, you should address   
     the following concerns:.

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    (a)   Inspections

          (i)    Frequency
          (ii)   What will be inspected?
          (iii)  Who will perform the inspections?
          (iv)   Operational checks

    (b)   Service

          (i)    Prearranged or on an "as-required" basis?
          (ii)   If prearranged, specify by agreement or service contract
          (iii)  Who will perform the service?

    (c)   Parts replacement

          (i)    How necessary replacement parts will be obtained
          (ii)   How suitability of any replacement parts (equal or better)    
                 will be determined

    (d)   Service, source exchange and 5-year inspections

          (i)    Identify the name of the organization(s) that will perform
                 these services and specify the firm's NRC or Agreement State
                 license number
          (ii)   If you have no organization identified to perform these
                 services, then what are your plans at source-exchange time
                 and/or 5-year inspection.

    (e)    For any needed repairs or essential inspections for which necessary 
           resources are unavailable or delayed, you must commit to halting
           all use of the unit until the necessary repairs and/or inspection 
           have been accomplished.

Address the required written reports to the U.S. Nuclear Regulatory
Commission, ATTN:  Document Control Desk, Washington, D.C. 20555, under oath
or affirmation, under the provisions of Section 182a, Atomic Energy Act of
1954, as amended.  In addition, submit a copy to the appropriate regional

This request is covered by Office of Management and Budget Clearance Number
3150-0017, which expires February 28, 1993.  The estimated average number of
burden hours is 20 person-hours per licensee response, including those needed
to assess the new recommendations, search data sources, gather and analyze the
data, and prepare the required letters.  (This estimate of the average number
of burden-hours pertains only to the identified response-related matters and
does not include the time needed to implement the requested action.)  Send
comments about this burden estimate or any other aspect of this collection of
information, including suggestions for reducing this burden, to the
Information and Records Management Branch, Division of Information Support
Services, Office of Information Resources Management, U.S. Nuclear Regulatory
Commission, Washington, D.C. 20555, and to the Paperwork Reduction Project  .

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(3150-0017), Office of Information and Regulatory Affairs, NEOB-3019, Office
of Management and Budget, Washington, D.C. 20503.

Although no specific request or requirement is intended, the following
information would be helpful to NRC in evaluating the cost of complying with
this bulletin:

(1)  The licensee staff's time and costs to perform requested inspections,
     corrective actions, and associated testing

(2)  The licensee staff's time and costs to prepare the requested reports and

(3)  The additional short-term costs incurred as a result of the inspection
     findings such, as the costs of the corrective actions or the costs of
     down time

(4)  An estimate of the additional long-term costs that will be incurred in
     the future as a result of implementing commitments such as the estimated
     costs of conducting future inspections or increased maintenance

If you have any questions about this matter, please contact the technical
contact listed below or the appropriate regional office. 

                                      ORIGINAL SIGNED BY

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

Technical contact:  Robert L. Ayres, IMAB

1.  CUB-91-03NA 
2.  CUB-91-04NA 
3.  List of Recently Issued NMSS Bulletins 
4.  List of Recently Issued NRC Bulletins


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