Information Notice 1994-39, Identified Problems in Gamma Stereotactic Radiosurgery
I
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
WASHINGTON, D.C.
20555
May 31, 1994
IDENTIFIED PROBLEMS IN GAMMA STEREOTACTIC
RADIOSURGERY
Addressees
All U.S. Nuclear Regulatory Commission Teletherapy Medical Licensees.
Purpose
NRC is issuing this information notice to alert addressees to problems
identified in gamma stereotactic radiosurgery. It is expected that recipients
will review this information for applicability to their facilities and
consider actions, as appropriate. However, suggestions contained in this
information notice are not new NRC requirements; therefore, no specific
actions nor written response are required.
Description of Circumstances
NRC has become aware of the following incidents and areas of concern in gamma
stereotactic radiosurgery:
1) An incident involving the failure of the treatment timer to activate
after collimator alignment;
2) Symmetrical primary beams of radiation exiting the stereotactic unit
when the shielding door was opened in the treatment mode;
3) An incident involving inadvertently inverting film of the treatment
site for input into the treatment planning system and the subsequent
overriding of the detection of the error by the treatment planning
system; and
4) A published study revealing the frequency of generating and
detecting human error in setting stereotactic coordinates for
radiosurgery.
Incident 1. A licensee started patient treatment and noticed that the timer
activation light and the timer did not come on when the patient was positioned
Flickinger, J.C., Lunsford, L.D., and Kondziolka, D., "Potential
Human Error in Setting Stereotactic Coordinates for Radiosurgery:
Implications for Quality Assurance,"
Int. J. Radiat. Oncol. Biol.
PhYs. 27(2); 397-41;1993.
Reprint requests to: John C. Flickinger, M.D., Joint Radiation Oncology Center, 230 Lothrop St., Pittsburgh, PA 15213.
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IN 94-39 May 31, 1994 in the treatment radiation field. The licensee reported that it used backup
timing by stopwatch to complete the exposure, when the patient couch did not
eject as expected. After completion of the treatment, the patient was removed
without incident. The equipment was inspected and a switch that should have
triggered the two timers and an indication of "Treatment Underway" was found
to be loose. After the switch was secured and adjusted, the unit operated
properly. The licensee concluded that this type of malfunction might occur at
any time when there is a gross misalignment of microswitches, broken wire, or
other disconnect between the switch and the timer mechanism.
Incident 2. In March 1992, an Agreement State notified NRC that a hospital
physicist detected two symmetrical beams of radiation exiting the stereotactic
radiosurgery unit when the shielding door was open in the treatment mode.
The
same problem was identified at two other facilities.
The Agreement State
required the manufacturer of the unit to evaluate the problem and take
corrective action.
The manufacturer subsequently informed the Agreement State
that two channels had allowed radiation to exit the unit unshielded. As a
corrective action, the manufacturer designed and completed a retrofit of all
existing units with a wall extension, to shield the two channels, by October
1992.
Incident 3. An arteriovenous malformation on the left side of the brain was
being treated.
An x-ray film was inverted before input into the treatment
planning system. The treatment planning system initially rejected the image, recognizing it only as an older orientation system.
Eventually, the
neurosurgeon and physicist overrode the program and instructed the program to
accept the reversed image. They then proceeded to generate treatment plans
for two separate targets. After completing the first of two 8-minute shots
for the first treatment plan and initiating the second, the physicist noticed
that the X coordinates of the target points for the second treatment plan
indicated a right-sided target, not left-sided as had been desired. He
immediately terminated the second shot, with approximately 5X minutes
remaining. After dose reconstruction, it was determined that the Y and Z
coordinates were correct; however, the X offset resulted in a target miss of
16 mm.
Journal Article. The journal article describes the determination of the error
rate in setting 396 isocenter treatments for 101 patients. Of the first 200,
the spontaneous errors in setting the stereotactic coordinates >0.25 mm were
determined to be 12 percent.
The errors were attributed to visual limitation, transposition of coordinates, and wrong isocenter set-up.
The second part of
the study determined the detection efficiency of observers in detecting 25 intentionally introduced errors in isocenter coordinate settings.
The error
detection efficiency of observers was 60.0 percent for 0.25 mm, 95.0 percent
for 0.50 mm, 94.4 percent for 1 to 20 mm, and 83.5 percent for all errors.
Discussion
The treatment-timer failure (Incident 1, above) highlights the importance of
proper maintenance and housekeeping of the stereotactic treatment unit, and
having a backup timing system to verify treatment time. If a check of the
system had been performed before the treatment, the loose switch might have
been detected and the incident avoided.
If the treatment facility had not had
IN 94-39 May 31, 1994 an auxiliary treatment timing system, the stopwatch, there might have been
difficulty in determining that the prescribed dose had been delivered.
However, according to the manufacturer, in the described condition, the
stereotactic treatment unit is equipped with a safety circuit that terminates
the treatment within approximately 2 minutes after the "Treatment Start"
button is pushed, and had the physicians not decided to interrupt the
treatment, the couch would have been ejected and the treatment interrupted
automatically, within a few seconds, thus limiting the total dose.
The radiation leakage (Incident 2, above) is of concern because if a staff
member had needed to attend to a patient during-treatment, he/she might have
been exposed to this unshielded primary beam of radiation.
The potential
existed for exceeding occupational dose limits.
Acceptance testing of
teletherapy units and gamma stereotactic radiosurgery units should always
include health physics surveys, to ensure the safety of staff members during
routine and non-routine uses. In this instance, the shielding retrofit by the
manufacturer should eliminate this particular area of concern.
The use of the inverted image (Incident 3, above) demonstrates to the
importance of understanding the software package used in treatment planning, and not bypassing warning signals without understanding or addressing the
warning or its cause.
Uninformed use of treatment planning software, without
independent verification (e.g., hand calculation, double check by a second
individual, etc.), may lead to serious consequences.
Fortunately, in this
case, the licensee reported that the dose was delivered to areas of the brain
"...
with extremely high tolerance for deficit, ar! that the dose delivered
was well below the dose-volume threshold for inducing any neurological
damage"; however, this may not be the case for future incidents of this
nature.
The journal article (Item 4, above) points out the importance of verification
of coordinate setting by a person other than the one setting the coordinates.
According to the study, an individual will set the coordinates incorrectly 12 percent of the time. If the coordinates are checked by an observer, the
errors will be detected on average 83.5 percent of the time, reducing the
number of undetected errors to approximately 2 percent.
Licensees are reminded that 10 C.F.R §35.32 requires, in part, the
establishment of a written Quality Management Program (QMP), to meet five
specific objectives for gamma stereotactic radiosurgery:
1) Prior to administration, a written directive** is prepared;
2) That, prior to each administration, the patient's identity is
verified by more than one method as the individual named in the
written directive;
For gamma stereotactic radiosurgery, a written directive means an
order in writing for a specific patient, dated and signed by an
authorized user prior to the administration of radiation, containing
the target coordinates, collimator size, plug pattern, and total
dose. 10 C.F.R. §35.2(3).
IN 94-39 May 31, 1994 3) That final plans of treatment and related calculations are in
accordance with the respective written directives;
4) That each administration is in accordance with the written
directive; and
5) That any unintended deviation from the written directive is
identified and evaluated, and appropriate action is taken.
Licensees should review their QMP to ensure that policies and procedures are
adequate to provide, as required by 10 C.F.R. §35.32(a), high confidence that
the radiation from the byproduct material will be administered as directed by
the authorized user.
This information notice requires no specific action nor written response. If
you have questions about the information in this notice, please contact the
technical contact listed below, or the appropriate regional office.
Carl J. Paperiel , Directo
Division of Industrial and
Medical Nuclear Safety
Office of Nuclear Material Safety
and Safeguards
Technical contact:
James Smith, NMSS
(301) 415-7904 Attachments:
1. List of Recently Issued NMSS Information Notices
2. List of Recently Issued NRC Information Notices
Attachment 1
May 31, 1994 LIST OF RECENTLY ISSUED
NMSS INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
94-37
94-35
Misadministration Caused
by a Bent Interstitial
Needle during Brachy- therapy Procedure
NIOSH Respirator User
Notices, "Inadvertent
Separation of the Mask- Mounted Regulator (MMR)
from the Facepiece on the
Mine Safety Appliances (MSA)
Company MMR Self-Contained
Breathing Apparatus (SCBA)
and Status Update"
Guidance to Hazardous,
Radioactive and Mixed
Waste Generators on the
Elements of A Waste
Minimization Program
05/27/94
05/16/94
03/25/94
All U.S. Nuclear Regulatory
Commission Medical Licensees
authorized to use brachy- therapy sources in high-,
medium-, and pulsed-dose- rate remote afterloaders.
All holders of OLs or CPs
for nuclear power reactors, and all licensed fuel
facilities.
All NRC licensees.
94-23
94-21
Regulatory Requirements
when No Operations are
being Performed
03/18/94
All fuel cycle and
licensees.
materials
94-17 Strontium-90 Eye Appli- cators: Submission of
Quality Management Plan
(QMP), Calibration, and
Use
Recent Incidents Resulting
in Offsite Contamination
03/11/94
03/03/94
All U.S. Nuclear Regulatory
Commission Medical Use
Licensees.
All U.S. Nuclear Regulatory
Commission material and fuel
cycle licensees.
94-16
Attachment 2
May 31, 1994 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
94-38
94-37
94-36
Results of a Special NRC
Inspection at Dresden
Nuclear Power Station
Unit 1 Following a Rupture
of Service Water Inside
Containment
Misadministration Caused
by a Bent Interstitial
Needle during Brachy- therapy Procedure
Undetected Accumulation
of Gas in Reactor
Coolant System
Switchyard Problems that
Contribute to Loss of
Offsite Power
NIOSH Respirator User
Notices, "Inadvertent
Separation of the Mask- Mounted Regulator (MMR)
from the Facepiece on the
Mine Safety Appliances (MSA)
Company MMR Self-Contained
Breathing Apparatus (SCBA)
and Status Update"
Thermo-Lag 330-660
Flexi-Blanket Ampacity
Derating Concerns
05/27/94
05/27/94
05/24/94
05/19/94
05/16/94
05/13/94
All holders of OLs or CPs
for NPRs and all fuel cycle
and materials licensees
authorized to possess spent
fuel.
All U.S. Nuclear Regulatory
Commission Medical Licensees
authorized to use brachy- therapy sources in high-,
medium-, and pulsed-dose- rate remote afterloaders.
All holders of OLs or CPs
for nuclear power reactors.
All holders of OLs or CPs
for nuclear power reactors.
All holders of OLs or CPs
for nuclear power reactors, and all licensed fuel
facilities.
All holders of OLs or CPs
for nuclear power reactors.
91-81, Supp. 1
94-35
94-34 OL = Operating License
CP = Construction Permit
IN 94-39 May 31, 1994 3) That final plans of treatment and related calculations are in
accordance with the respective written directives;
4) That each administration is in accordance with the written
directive; and
5) That any unintended deviation from the written directive is
identified and evaluated, and appropriate action is taken.
Licensees should review their QMP to ensure that policies and procedures are
adequate to provide, as required by 10 C.F.R. §35.32(a), high confidence that
the radiation from the byproduct material will be administered as directed by
the authorized user.
This information notice requires no specific action nor written response. If
you have questions about the information in this notice, please contact the
technical contact listed below, or the appropriate regional office.
Carl J. Paperiello, Director
Division of Industrial and
Medical Nuclear Safety
Office of Nuclear Material Safety
and Safeguards
Technical contact:
James Smith, NMSS
(301) 415-7904 Attachments:
1. List of Recently Issued NMSS Information Notices
2. List of Recently Issued NRC Information Notices
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94-39. IN
Official Record Copy
NMSS HEADQUARTERS DAILY REPORT FORM
OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
May 31, 1994
INFORMATION NOTICE NO. 94- 39,"Identified Problems In Gamma Stereotactic
Radiosuraervy
was issued on May 31. 1994 .
(date)
The technical contact is James A. Smith.Jr. O
, ext. 415-7904 Summary:
The NRC has identified the following areas of concern in gamma
stereotactic radiosurgery: a published study of the frequency of
generating and detecting human error in setting stereotactic
coordinates for radiosurgery; symmetrical primary beams of
radiation exiting the stereotactic unit when the shielding door
was opened in the treatment mode; an incident inadvertent
inverting of film of the treatment site for input into the
treatment planning system and the subsequent overriding of the
detection of the error by the treatment planning system; and an
incident involving the failure of the treatment timer to activate
after collimator alignment.
V.>
<_IN
94- May
, 1994 3)
That final plans of treatment and related calculations are in
accordance with the respective written directives;
4)
That each administration is in accordance with the written
directive; and
5)
That any unintended deviation from the written directive is
identified and evaluated, and appropriate action is taken.
Licensees should review their QMP to ensure that policies and procedures are
adequate to provide, as required by 10 C.F.R. §35.32(a), high confidence that
the radiation from the byproduct material will be administered as directed by
the authorized user.
This information notice requires no specific action nor written response. If
you have questions about the information in this notice, please contact the
technical contact listed below, or the appropriate regional office.
Carl J. Paperiello, Director
Division of Industrial and
Medical Nuclear Safety
Office of Nuclear Material Safety
and Safeguards
Technical contact:
James Smith, NMSS
(301) 415-7904 Attachments:
1. List of Recently Issued NMSS Information Notices
2. List of Recently Issued NRC Information Notices
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