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
From:	Cool D NRC/NMSS/IMNS
To:
References
IN-96-072, NUDOCS 9612310159
Download: ML031050467 (11)

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON, D.C. 20555 December 24, 1996 NRC INFORMATION NOTICE 96-72: UNDETECTED FAILURES THAT MAY OCCUR

DURING PATIENT TREATMENTS WiTH

TELETHERAPY DEVICES

Addressees

All teletherapy licensees.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert

addressees to a recently reported failure of an AECL Theratron 780 teletherapy device to

place the source in the exposure position during patient treatment, and the potential for

similar 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 for

applicability 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 was

experiencing electrical problems with an AECL Theratron 780 teletherapy unit. On

November 27, 1996, the licensee's radiation therapy technologist observed that the cobalt-60

teletherapy 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 indication

of 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, the

information provided by the operating treatment timer conflicted with that from both the

beam-on indicator and room radiation monitor. Upon observation of this problem, the

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IN 96-72 December 24, 1996 treatment was terminated by licensee staff. When the teletherapy physicist subsequently

evaluated the control panel operation he discovered a sporadic failure of the source to move

to the exposed position, despite normal operation of the treatment timer.

On December 2, 1996, a service representative from Therstronics International Corporation

arrived at the licensee's site. The service representative concluded that a loose wire

connection, between the timer and the solenoid driver circuit board, was causing a sporadic

circuit interruption which, in turn, prevented the activation of the driver necessary to move the

source into the exposed position. The control console lights were found to be functioning

normally; however, since the timer was not connected to any source position indicators, it

continued 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 service

representative determined the unit was fully operational.

The device subsequently failed again on December 9, 1996, in a manner similar to that of the

previously reported November 27, 1996, failure. This second failure has been attributed to a

faulty solenoid driver circuit board, which was replaced by the Theratronics service

representative. The first test of the unit, with the replacement circuit board in place, also

resulted in the same system failure. However, neither the service representative or

inspectors from both the Food and Drug Administration (FDA) and NRC have been able to

reproduce this latest failure following replacement of the circuit board. Thus, the root cause

of these failures has yet to be determined and efforts are continuing to make this

determination.

Discussion

Review of this incident reveals that the malfunctioning unit was an early model Theratron 780

using a single channel timer. These single channel timers can be of either mechanical or

digital designs. With this type of timer, originally installed on all AECL/Theratronics

teletherapy units built before 1985, patient treatments are initiated by starting the treatment

timer which, in turn, generates the signal to move the source to the exposed treatment

position. If, for any reason, the source fails to move to the exposed treatment position, the

timer will continue to run without interruption. This would result in the patient receiving less

than the intended dose for that treatment fraction. Additionally, this can occur not only upon

the 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 fully

exposed treatment position is not observed, and subsequently corrected, by the licensee.

Since these older generation devices have this known single-point failure mode, it is

important that licensees be especially vigilant in monitoring all status information available on

the initiation, and throughout the course, of treatment. These would include not only the

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IN 96-72 December 24, 1996 the room radiation

timer count down, but the source position indicators and, if appropriate,does not necessarily mean

monitor alarm output. The illumination of the "Beam On" indicator

source is not in the fully

that the source is in the exposure position, but merely indicates the

shielded position.

channel timer units, the

For the older (prior to 1985) AECLUTheratron devices with single more recent design. Since

manufacturer presently offers a replacement dual channel timer of they may no longer carry

some of these units may have been refurbished by other vendors,concerning whether or not

the AECL/Theratronics identification. If you have any questions or refurbisher. The

your unit is susceptible to this failure, contact either your service provider

older single channel timers

replacement timer is designed to operate quite differently than the

installed, is likely that

it

it is intended to replace. Had this dual channel timer upgrade been position would

the failure of the device to move the source into the fully exposed treatment undetected patient

have been more readily detected by the licensee and the potential for

underexposures reduced.

NRC that it intends to notify

The vendor (Theratronics International Corporation) has informed of the potential

all its customers having these older single-timer units, advising them of this vendor's

problems and the vendors recommended corrective actions. A copy

vendor directly with

notification is attached (Attachment 1). Licensees should contact the

questions related to the notification.

replacement

Licensees should consider increasing their preventive maintenance procedures, such as these

of parts, and upgrading of components (when available) for older devices, life. When

teletherapy units, that may be approaching the end of their safe useful studies that indicate that

considering options, licensees may wish to consider human factors if one operational

people are poor at detecting intermittent or infrequent failures, particularly

others.

indicator, such as the treatment timer, is monitored more closely than

are now subject to

Licensees should also be aware that medical device user facilities devices. Information

mandatory FDA adverse event reporting requirements for medical by contacting the

concerning FDA's mandatory reporting requirements can be obtained and Biometrics, Division of

Center for Devices and Radiological Health, Office of Surveillance reporting requirements

Surveillance Systems at (301) 594-2735. Since the FDA mandatory on information

may not be applicable to all medical device events, FDA also depends recognize medical

voluntarily provided by device users because they are often the first to to the safety or

device related hazards. Any concerns that licensees may have pertaining reported to the FDA by

quality problems associated with medical devices can be voluntarily anonymously.

calling MedWatch at 1-800-FDA-1088. Voluntary reports can be submitted

IN 96-72 December 24, 1996 response. If you have any

This information notice requires no specific action nor written

technical contact listed

questions about the information in this notice, please contact the

below or the appropriate NRC regional office.

( I ol,D or

'D sion of Industrial and

Medical Nuclear Safety

Office of Nuclear Material Safety

and Safeguards

Robert L. Ayres, NMSS

(301) 415-5746 E-mail: rxal nrc.gov

Attachments:

1. Theratronics Customer Notification

2. List of Recently Issued NMSS Information Notices

3. List of Recently Issued NRC Information Notices

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Attachment 1 IN 96-72 AY@ATTRONICSU R NC December 24, 1996

)W Intematonla Limred

December 10, 1996 Dear Theraton Customer, OF

SUBJECT: REMINDER FOR SINGLE-CHANNEL TIMER UNITS

PRECAUTIONS IN TflE OPERATOR'S MANUAL

Model:_

SIN:

timers, eier mechanical or digital.

Thratron units shipped prior to 1985 included single-channel

Both of these models are designed to begintheir timing sequence from the source-on comnmand

switches as in the more recent Theratron

rather than directly from the source transit drawer problem in the soure

or mechanical

models. With these older single-channel tmers, an electrical titme.

of treatment

mechanism, should it go unnoticed, could affect the accuracy

years and reports of problems have

Singlchannel timers have been in use for more than thirty

Users df units having single

been very rare with no reports of significant dose misadministration.

operating precautions:

channel timers, however, are reminded of the foLlowing standard

of the Source

1. As is explained in the Operator's Manual, observe the operion

and above thie treatment room door

Position indicator lights on the control console

while treatment is in progress.

nstructions ouidined in

2. Follow daily start-up procedures and periodic maintenance

the Operator's Manual, and investigate any problems promptly.

models, which will improve

Kits are available to install the current Dual Timer on older Theratronand delivery information at

price

timer accuracy and reliability. Please contact Tlheratronics for

1-800-826-2258 or 1-800-267-7230.

E.S. Maxtell

Vice President

Quality Assurance and Regulatory Affairs

413 March Road

P.O. Box 13140 O/

Kanata Ontario Canada ISOC9001a1994 n' Doi 0

21287

(613) 591-2100 Knatam Ontario. Canada

Fax 613 592-3816

Attachment 2 IN 96-72 December 24, 1996 Page 1 of I

LIST OF RECENTLY ISSUED

NMSS INFORMATION NOTICES

Information Date of

Subject Issuance Issued to

Notice No.

12/24/96 All U.S. Nuclear Regulatory

96-70 Year 2000 Effect on Computer

Commission licensees, certi- System Software

ficate holders, and regis- trants

Recent Misadministrations 12/13/96 All U.S. Nuclear Regulatory

96-66 Commission Medical Use

Caused by Incorrect Cali- Licensees authorized to use

brations of Strontium-90

strontium-90 eye applicators

Eye Applicators

Potential Safety Issue 12/05/96 All U.S. Nuclear Regulatory

96-63 Commission licensees

Regarding the Shipment

of Fissile Material authorized to possess special

nuclear material in unsealed

quantities greater than a

critical mass

Incident-Reporting Require- 10/30/96 All U.S. Nuclear Regulatory

96-57 Commission licensees

ments Involving Intakes, During a 24-Hour Period

that May Cause a Total

Effective Dose Equivalent

in Excess of 0.05 Sv (5 rem)

10/17/96 All material licensees

96-54 Vulnerability of Stainless

Steel to Corrosion When

Sensitized

10/15/96 All industrial radiography

96-53 Retrofit to Amersham 660

licensees

Posilock Radiography

Camera to Correct Incon- sistency in 10 CFR Part 34 Compatibility

09/26/96 All U.S. Nuclear Regulatory

96-52 Cracked Insertion Rods

Commission portable gauge

on Troxler Model 3400

Series Portable Moisture licensees and vendors

Density Gauges

N

Attachment 3 IN 96-72 December 24, 1996 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Subject Issuance Issued to

Notice No.

Licensee Response to Indi- 12/27/96 All holders of OLs

96-71 or CPs for nuclear

cations of Tampering, Van- power reactors

dalism, or Malicious Mis- chief

Year 2000 Effect on Computer 12/24/96 All U.S. Nuclear

96-70 Regulatory Commission

System Software

licensees, certificate

holders, and registrants

Operator Actions Affecting 12/20/96 All holders of OLs

96-69 or CPs for nuclear

Reactivity

power reactors

Incorrect Effective Diaphragm 12/19/96 All holders of OLs

96-68 or CPs for nuclear

Area Values in Vendor Manual

Result in Potential Failure power reactors

of Pneumatic Diaphragm

Actuators

Vulnerability of Emergency 12/19/96 All holders of OLs

96-67 Diesel Generators to Fuel or CPs for nuclear

Oil/Lubricating Oil Incom- power reactors

patibility

Recent Misadministrations 12/13/96 All U.S. Nuclear

96-66 Regulatory Commission

Caused by Incorrect Cali- brations of Strontium-90 Medical Use Licensees

Eye Applicators authorized to use

strontium-90 (Sr-90)

eye applicators

OL = Operating License

CP = Construction Permit

IIIN 96-72 December 24, 1996 This information notice requires no specific action nor written response. If you have any

questions about the information In this notice, please contact the technical contact listed

below or the appropriate NRC regional office.

Umgse1 Signed by 4 a~ ~

Donald A. Cool, Director v

• Division of Industrial and

Medical Nuclear Safety

Office of Nuclear Material Safety

and Safeguards

Robert L. Ayres, NMSS

(301) 415-5746 E-mail: rxal@nrc.gov

Attachments:

1. Theratronics Customer Notification

2. List of Recently Issued NMSS Information Notices

3. List of Recently Issued NRC Information Notices

• See previous concurrence

• • rd^A4n2*&A with FDA

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96-XX

~ December , 1996 Licensees should consider increasing their preventive maintenance procedures, older

replacement of parts, and upgrading of components (when available) forend of

devices, such as these teletherapy units, that may be approaching the

their safe useful life. When considering options, licensees may wish to

consider human factors studies that indicate that people are poor at detecting

intermittent or infrequent failures, particularly if one operational

indicator, such as the treatment timer, is monitored more closely than others.

Licensees should also be aware that medical device user facilities are now

subject to mandatory FDA adverse event reporting requirements for medicalcan be

devices. Information concerning FDA's mandatory reporting requirements

obtained by contacting the Center for Devices and Radiological Health, Office

of Surveillance and Biometrics, Division of Surveillance Systems at (301) 594-

2735. Since the FDA mandatory reporting requirements may not be applicable to

all medical device events, FDA also depends on information voluntarily

provided by device users because they are often the first to recognize medical

device related hazards. Any concerns that licensees may have pertaining to

the safety or quality problems associated with medical devices can be

voluntarily 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. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate NRC regional office.

Donald A. Cool, Director

Division of Industrial and

Medical Nuclear Safety

Office of Nuclear Material Safety

and Safeguards

Robert L. Ayres, NMSS

(301) 415-5746 E-mail: rxal~nrc.gov

Attachments:

1. Theratronics Customer Notification

2. List of Recently Issued NMSS Information Notices

3. List of Recently Issued NRC Information Notices

• See previous concurrence

• • Coordinated with FDA ===a

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IN 96-XX

December 1996 This information notice requires no specific action nor written response. If you

have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRC regional office.

Donald A. Cool, Director

Division of Industrial and

Medical Nuclear Safety

Office of Nuclear Material Safety

and Safeguards

Robert L. Ayres, NMSS

(301) 415-5746 E-mail: rxal@nrc.gov

Attachments:

1. Theratronics Customer Notification

2. List of Recently Issued NMSS Information Notices

3. List of Recently Issued NRC Information Notices

• See previous concurrence

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IN 96-XX

December 1996 This information notice requires no specific action nor written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate NRC regional office.

Donald A. Cool, Director

Division of Industrial and

Medical Nuclear Safety

Office of Nuclear Material Safety

and Safeguards

Robert L. Ayres, NMSS

(301) 415-5746 E-mail: rxal@nrc.gov

Attachments:

1. Theratronics Customer Notification

2. List of Recently Issued NMSS Information Notices

3. List of Recently Issued NRC Information Notices

• See previous concurrence A

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