Information Notice 1996-72, Undetected Failures That May Occur During Patient Treatments with Teletherapy Devices

Undetected Failures That May Occur During Patient Treatments with Teletherapy Devices

ML031050467
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	12/24/1996
Revision:	0
From:	Cool D A NRC/NMSS/IMNS
To:
References
IN-96-072, NUDOCS 9612310159
Download: ML031050467 (11)

K)jUNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDSWASHINGTON, D.C. 20555December 24, 1996NRC INFORMATION NOTICE 96-72: UNDETECTED FAILURES THAT MAY OCCURDURING PATIENT TREATMENTS WiTHTELETHERAPY DEVICES

Addressees

All teletherapy licensees.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alertaddressees to a recently reported failure of an AECL Theratron 780 teletherapy device toplace the source in the exposure position during patient treatment, and the potential forsimilar failures in all older AECL teletherapy devices that were manufactured prior to 1985.These include the Theratron T765, T80, and T60 model numbers, and the Eldorado E78,E76, E8, and E6 model numbers. It. is expected that recipients will review the information forapplicability to their facilities and consider actions, as appropriate, to avoid similar problems.However, suggestions contained in this information notice are not NRC requirements;therefore, no specific action nor written response is required.

Description of Circumstances

On November 29, 1996, a licensee's teletherapy physicist notified NRC that he wasexperiencing electrical problems with an AECL Theratron 780 teletherapy unit. OnNovember 27, 1996, the licensee's radiation therapy technologist observed that the cobalt-60teletherapy source was not in the exposure (beam-on) position during a patient treatment,even though the treatment timer was running. The running treatment timer was an indicationof in-progress patient treatment. However, the beam-on indicator light was not illuminated,nor was the room radiation monitor indicating the presence of radiation. Thus, theinformation provided by the operating treatment timer conflicted with that from both thebeam-on indicator and room radiation monitor. Upon observation of this problem, the(OR t o+wrt 9 4- -9(1'"q/4L391' tha /151' 7 +

v'UIN 96-72December 24, 1996 treatment was terminated by licensee staff. When the teletherapy physicist subsequentlyevaluated the control panel operation he discovered a sporadic failure of the source to moveto the exposed position, despite normal operation of the treatment timer.On December 2, 1996, a service representative from Therstronics International Corporationarrived at the licensee's site. The service representative concluded that a loose wireconnection, between the timer and the solenoid driver circuit board, was causing a sporadiccircuit interruption which, in turn, prevented the activation of the driver necessary to move thesource into the exposed position. The control console lights were found to be functioningnormally; however, since the timer was not connected to any source position indicators, itcontinued to run even though the source was not in the exposed patient treatment position.Following repair of the loose wire connection to the circuit board the Theratronics servicerepresentative determined the unit was fully operational.The device subsequently failed again on December 9, 1996, in a manner similar to that of thepreviously reported November 27, 1996, failure. This second failure has been attributed to afaulty solenoid driver circuit board, which was replaced by the Theratronics servicerepresentative. The first test of the unit, with the replacement circuit board in place, alsoresulted in the same system failure. However, neither the service representative orinspectors from both the Food and Drug Administration (FDA) and NRC have been able toreproduce this latest failure following replacement of the circuit board. Thus, the root causeof these failures has yet to be determined and efforts are continuing to make thisdetermination.DiscussionReview of this incident reveals that the malfunctioning unit was an early model Theratron 780using a single channel timer. These single channel timers can be of either mechanical ordigital designs. With this type of timer, originally installed on all AECL/Theratronicsteletherapy units built before 1985, patient treatments are initiated by starting the treatmenttimer which, in turn, generates the signal to move the source to the exposed treatmentposition. If, for any reason, the source fails to move to the exposed treatment position, thetimer will continue to run without interruption. This would result in the patient receiving lessthan the intended dose for that treatment fraction. Additionally, this can occur not only uponthe initiation of treatment, but at any time the source exposure signal pathway is interrupted.Potential harm to the patient could occur if the failure of the source to move to the fullyexposed treatment position is not observed, and subsequently corrected, by the licensee.Since these older generation devices have this known single-point failure mode, it isimportant that licensees be especially vigilant in monitoring all status information available onthe initiation, and throughout the course, of treatment. These would include not only the K)IN 96-72December 24, 1996 timer count down, but the source position indicators and, if appropriate, the room radiationmonitor alarm output. The illumination of the "Beam On" indicator does not necessarily meanthat the source is in the exposure position, but merely indicates the source is not in the fullyshielded position.For the older (prior to 1985) AECLUTheratron devices with single channel timer units, themanufacturer presently offers a replacement dual channel timer of more recent design. Sincesome of these units may have been refurbished by other vendors, they may no longer carrythe AECL/Theratronics identification. If you have any questions concerning whether or notyour unit is susceptible to this failure, contact either your service provider or refurbisher. Thereplacement timer is designed to operate quite differently than the older single channel timersit is intended to replace. Had this dual channel timer upgrade been installed, it is likely thatthe failure of the device to move the source into the fully exposed treatment position wouldhave been more readily detected by the licensee and the potential for undetected patientunderexposures reduced.The vendor (Theratronics International Corporation) has informed NRC that it intends to notifyall its customers having these older single-timer units, advising them of the potentialproblems and the vendors recommended corrective actions. A copy of this vendor'snotification is attached (Attachment 1). Licensees should contact the vendor directly withquestions related to the notification.Licensees should consider increasing their preventive maintenance procedures, replacementof parts, and upgrading of components (when available) for older devices, such as theseteletherapy units, that may be approaching the end of their safe useful life. Whenconsidering options, licensees may wish to consider human factors studies that indicate thatpeople are poor at detecting intermittent or infrequent failures, particularly if one operationalindicator, such as the treatment timer, is monitored more closely than others.Licensees should also be aware that medical device user facilities are now subject tomandatory FDA adverse event reporting requirements for medical devices. Informationconcerning FDA's mandatory reporting requirements can be obtained by contacting theCenter for Devices and Radiological Health, Office of Surveillance and Biometrics, Division ofSurveillance Systems at (301) 594-2735. Since the FDA mandatory reporting requirementsmay not be applicable to all medical device events, FDA also depends on informationvoluntarily provided by device users because they are often the first to recognize medicaldevice related hazards. Any concerns that licensees may have pertaining to the safety orquality problems associated with medical devices can be voluntarily reported to the FDA bycalling MedWatch at 1-800-FDA-1088. Voluntary reports can be submitted anonymously.

IN 96-72December 24, 1996 This information notice requires no specific action nor written response. If you have anyquestions about the information in this notice, please contact the technical contact listedbelow or the appropriate NRC regional office.( I ol, D or'D sion of Industrial andMedical Nuclear SafetyOffice of Nuclear Material Safetyand Safeguards

Technical Contact:

Robert L. Ayres, NMSS(301) 415-5746E-mail: rxal nrc.gov

Attachments:

1. Theratronics Customer Notification2. List of Recently Issued NMSS Information Notices3. List of Recently Issued NRC Information Notices1# 4h 1{- J21ez /

iAttachment 1AY@ATTRONICS IN 96-72)W U R NC December 24, 1996Intematonla Limred December 10, 1996

Dear Theraton Customer,

SUBJECT: REMINDER FOR SINGLE-CHANNEL TIMER UNITS OFPRECAUTIONS IN TflE OPERATOR'S MANUALModel:_SIN:Thratron units shipped prior to 1985 included single-channel timers, eier mechanical or digital.Both of these models are designed to begin their timing sequence from the source-on comnmandrather than directly from the source transit drawer switches as in the more recent Theratronmodels. With these older single-channel tmers, an electrical or mechanical problem in the souremechanism, should it go unnoticed, could affect the accuracy of treatment titme.Singlchannel timers have been in use for more than thirty years and reports of problems havebeen very rare with no reports of significant dose misadministration. Users df units having singlechannel timers, however, are reminded of the foLlowing standard operating precautions:1. As is explained in the Operator's Manual, observe the operion of the SourcePosition indicator lights on the control console and above thie treatment room doorwhile treatment is in progress.2. Follow daily start-up procedures and periodic maintenance nstructions ouidined inthe Operator's Manual, and investigate any problems promptly.Kits are available to install the current Dual Timer on older Theratron models, which will improvetimer accuracy and reliability. Please contact Tlheratronics for price and delivery information at1-800-826-2258 or 1-800-267-7230.E.S. MaxtellVice PresidentQuality Assurance and Regulatory Affairs413 March RoadP.O. Box 13140Kanata Ontario Canada O/21287 ISOC9001a1994 n' Doi 0(613) 591-2100Fax 613 592-3816 Knatam Ontario. Canada Attachment 2IN 96-72December 24, 1996Page 1 of ILIST OF RECENTLY ISSUEDNMSS INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to96-7096-6696-6396-5796-5496-5396-52Year 2000 Effect on ComputerSystem SoftwareRecent MisadministrationsCaused by Incorrect Cali-brations of Strontium-90Eye ApplicatorsPotential Safety IssueRegarding the Shipmentof Fissile MaterialIncident-Reporting Require-ments Involving Intakes,During a 24-Hour Periodthat May Cause a TotalEffective Dose Equivalentin Excess of 0.05 Sv (5 rem)Vulnerability of StainlessSteel to Corrosion WhenSensitizedRetrofit to Amersham 660Posilock RadiographyCamera to Correct Incon-sistency in 10 CFR Part 34CompatibilityCracked Insertion Rodson Troxler Model 3400Series Portable MoistureDensity Gauges12/24/9612/13/9612/05/9610/30/9610/17/9610/15/9609/26/96All U.S. Nuclear RegulatoryCommission licensees, certi-ficate holders, and regis-trantsAll U.S. Nuclear RegulatoryCommission Medical UseLicensees authorized to usestrontium-90 eye applicatorsAll U.S. Nuclear RegulatoryCommission licenseesauthorized to possess specialnuclear material in unsealedquantities greater than acritical massAll U.S. Nuclear RegulatoryCommission licenseesAll material licenseesAll industrial radiographylicenseesAll U.S. Nuclear RegulatoryCommission portable gaugelicensees and vendors NAttachment 3IN 96-72December 24, 1996 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to96-7196-7096-6996-6896-6796-66Licensee Response to Indi-cations of Tampering, Van-dalism, or Malicious Mis-chiefYear 2000 Effect on ComputerSystem SoftwareOperator Actions AffectingReactivityIncorrect Effective DiaphragmArea Values in Vendor ManualResult in Potential Failureof Pneumatic DiaphragmActuatorsVulnerability of EmergencyDiesel Generators to FuelOil/Lubricating Oil Incom-patibilityRecent MisadministrationsCaused by Incorrect Cali-brations of Strontium-90Eye Applicators12/27/9612/24/9612/20/9612/19/9612/19/9612/13/96All holders of OLsor CPs for nuclearpower reactorsAll U.S. NuclearRegulatory Commissionlicensees, certificateholders, and registrantsAll holders of OLsor CPs for nuclearpower reactorsAll holders of OLsor CPs for nuclearpower reactorsAll holders of OLsor CPs for nuclearpower reactorsAll U.S. NuclearRegulatory CommissionMedical Use Licenseesauthorized to usestrontium-90 (Sr-90)eye applicatorsOL = Operating LicenseCP = Construction Permit I IIN 96-72December 24, 1996 This information notice requires no specific action nor written response. If you have anyquestions about the information In this notice, please contact the technical contact listedbelow or the appropriate NRC regional office.Umgse1 Signed by4 a~ ~Donald A. Cool, Director* Division of Industrial andMedical Nuclear SafetyOffice of Nuclear Material Safetyand Safeguardsv

Technical Contact:

Robert L. Ayres, NMSS(301) 415-5746E-mail: rxal@nrc.gov

Attachments:

1. Theratronics Customer Notification2. List of Recently Issued NMSS Information Notices3. List of Recently Issued NRC Information Notices* See previous concurrence** rd^A4n2*&A with FDAOFC IMAB I I/ IMAB IMAB IMOB INAME R *SMerchant *LwCamper *JPicconeDATE 12/-/9 _ 12/17 12/17/96 12/18/96_ ., , a I IT^~ICA InnttAM Inl/INS II0kroAE *Erause I *DACool In.air1'JI11 /9h12/18/96UVIA I _ A__ 1 A _W_ I -1FV.j -- I' _ __,___.;-- L riI a1,9tTVi nCITYPTA Duri.Dn QDVy IG. TfI _THEPRurrYE EmUVKSALU~t ncvvn i.urr US u .Ll 5 nrl*-TN,=COVER E=G0YER\FN6L0UbUKcnanu COP IUrrUPIALRL.%.VgW WV&. N 96-XX~ December , 1996 Licensees should consider increasing their preventive maintenance procedures,replacement of parts, and upgrading of components (when available) for olderdevices, such as these teletherapy units, that may be approaching the end oftheir safe useful life. When considering options, licensees may wish toconsider human factors studies that indicate that people are poor at detectingintermittent or infrequent failures, particularly if one operationalindicator, such as the treatment timer, is monitored more closely than others.Licensees should also be aware that medical device user facilities are nowsubject to mandatory FDA adverse event reporting requirements for medicaldevices. Information concerning FDA's mandatory reporting requirements can beobtained by contacting the Center for Devices and Radiological Health, Officeof Surveillance and Biometrics, Division of Surveillance Systems at (301) 594-2735. Since the FDA mandatory reporting requirements may not be applicable toall medical device events, FDA also depends on information voluntarilyprovided by device users because they are often the first to recognize medicaldevice related hazards. Any concerns that licensees may have pertaining tothe safety or quality problems associated with medical devices can bevoluntarily reported to the FDA by calling MedWatch at 1-800-FDA-1088.Voluntary reports can be submitted anonymously.This information notice requires no specific action nor written response. Ifyou have any questions about the information in this notice, please contactthe technical contact listed below or the appropriate NRC regional office.Donald A. Cool, DirectorDivision of Industrial andMedical Nuclear SafetyOffice of Nuclear Material Safetyand Safeguards

Technical Contact:

Robert L. Ayres, NMSS(301) 415-5746E-mail: rxal~nrc.gov

Attachments:

1. Theratronics Customer Notification2. List of Recently Issued NMSS Information Notices3. List of Recently Issued NRC Information Notices* See previous concurrence** Coordinated with FDA===aOFC IMAB I lE IMAB I IMAB I h140 fINAME Rayres *4^ *SMerchant *LWCamper I XpcfoneDATE ay2///96 12/17/96 12/17/96 _12/1/96/ I A .,.2 _ I _ItO TLr.8 I I "-Rn1TMNQ P I nl/TIwst/l -k4 IUrt-i ItLAILU I VV W41 e I *1-a.WNAME *EKrause F i s -_______ol__DATE 12/11/96 / -12/ /96 \ 12/Ir/96.-. 0..mr uuns r nur AECTALI rDnCOn MY: 6:\TFaLETHER.IN.COYER E=COYER\ENLh6LuWKN=nU Our IVI I &ULA. 5%1wuwo- WvrM. I II IN 96-XXDecember 996This information notice requires no specific action nor written response. If youhave any questions about the information in this notice, please contact thetechnical contact listed below or the appropriate NRC regional office.Donald A. Cool, DirectorDivision of Industrial andMedical Nuclear SafetyOffice of Nuclear Material Safetyand Safeguards

Technical Contact:

Robert L. Ayres, NMSS(301) 415-5746E-mail: rxal@nrc.gov

Attachments:

1. Theratronics Customer Notification2. List of Recently Issued NMSS Information Notices3. List of Recently Issued NRC Information Notices* See previous concurrence** rnnrlinatad with FfAOFC l IMAB r IMAB lI l IMAB I l IMOB I l_ INAME Rayres *SMerchant*LWCamper JPicconeDATE 12//e/96 12/17/96 12/17/96 12/ /96 _OFI_TpchFdIDD/IMNS ID/IMNS IIWAME I *EKrause FCCombs DACool InflTr1 1 Ill12/ /9612/ /96.. -O- -_. ...fPPEU % E1 T l url.EOE __0ERECL~R __=N LW'!A ,, ADA lL KLLIQ L^rl ~a; nrrLflI.^n Anv.rrrTM]_C-COVER E=COVER\ENCLUSUREH=NU Wryt UrrI1ARL KLLUKU Curl;U;%1LL1 7L *U K-IN 96-XXDecember 996This information notice requires no specific action nor written response. Ifyou have any questions about the information in this notice, please contactthe technical contact listed below or the appropriate NRC regional office.Donald A. Cool, DirectorDivision of Industrial andMedical Nuclear SafetyOffice of Nuclear Material Safetyand Safeguards

Technical Contact:

Robert L. Ayres, NMSS(301) 415-5746E-mail: rxal@nrc.gov

Attachments:

1. Theratronics Customer Notification2. List of Recently Issued NMSS Information Notices3. List of Recently Issued NRC Information Notices* See previous concurrenceAOFC IMAB I " -IMAB 1l 8:Yw I ' IMOB I lNAME Rayre s 99i SMert~ (" Sy/dmper JPicconeDATE 1 12//7/96 12/fl/96 /1 96 12/ /96* .... .. .OFCTechEd IDD/IMNS ID/IMNS IINAME *EKrause FCCombs DACool I _ _ _DATE 12/11/96 12/ /96 12/ /96 _____ I*nh rr. en r- rn rnrain -..r ..

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