Information Notice 1999-09, Problems Encountered When Manually Editing Treatment Data on the Nucletron Microselectron-HDR (New) Model 105-999
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
WASHINGTON, D.C. 20555
March 24, 1999 NRC INFORMATION NOTICE 99-09: PROBLEMS ENCOUNTERED WHEN MANUALLY
EDITING TREATMENT DATA ON THE NUCLETRON
MICROSELECTRON-HDR (NEW) MODEL 105.999
Addressees
All medical licensees authorized to conduct high-dose-rate (HDR) remote after loading
brachytherapy treatments.
PurDose:
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert
addressees to the potential for patient misadministrations that may result from inadvertent
changes to source step size that can occur when editing dwell time data. It is expected that
recipients will review the information for applicability to their facilities and consider actions, as
appropriate, to address these issues. However, suggestions contained in this information
notice are not new NRC requirements; therefore, no specific action, nor written response, is
required.
Description of Circumstances
On February 26, 1999, an NRC licensee reported a misadministration that had occurred in the
first fraction of a planned treatment of two fractions of 500 cGy (500 Rads) each for an HDR
vaginal treatment. The sequence of events leading up to this misadministration began with the
licensee encountering difficulty in electronically transferring the treatment plan, for this patient, from its Nucletron treatment planning system to their Nucletron microSelectron HDR treatment
system. After several unsuccessful attempts at electronically transferring the patient's
treatment plan to the treatment system, the licensee elected to manually enter the treatment
plan directly into the treatment system's control station. This was accomplished without
apparent difficulty.
On reviewing the printout of the treatment plan, before beginning treatment, the radiation
oncologist noted that the planned source dwell times were incorrect and instructed that the plan
be revised to the correct dwell times. While making the
required manual entry changes to edit the source dwell times, the keystrokes used in
completing the data entry field changes caused the source step size to change from 2.5 mm to
10 mm. The licensee did not notice this change and the patient, therefore, was treated usin
99 0T31 90
q227q
O q M6V f\\
IN 99-09 March 24, 1999 the incorrect step size. This resulted in the dose to the intended treatment site being less than
50 percent of the intended dose and considerable unintended dose to tissue distal to the
intended treatment site. The licensee attributes this unintended and unnoticed change in step
size to a software problem with the software used in the Nucletron treatment control station
(TCS). However, had the licensee properly reviewed the complete final treatment plan, immediately before treatment, this misadministration could have been prevented.
Discussion:
A review of the preliminary inspection information related to this misadministration indicated that
there were two software problems that contributed to this event: one with the Nucletron Plato
Treatment Planning system; and, one with the microSelectron-HDR treatment control station.
The documented problem with the treatment planning system was the inability to transfer the
treatment plan to the HDR treatment system from the treatment planning system via disk or
electronically. The microSelectron-HDR treatment system problem was the heretofore
undetected possibility of making unintended and unnoticed changes to the source step size, while editing an unrelated parameter.
The manual data entry into, and subsequent editing of these data on, the Nucletron TCS were
necessitated by the licensee's inability to transfer the original treatment plan for the Nucletron
Plato treatment planning system to the TCS via either the network interface or floppy disk.
Attempts to perform either type of transfer produced a "Error writing to file" with no indication of
what is causing the problem.
A Nucletron service engineer investigated the cause of this transfer problem and found it to
result from an undocumented limitation on the maximum number of combined patient and
applicator points that can be transferred. When a treatment plan has more than 24 combined
patient and applicator points, the treatment planning system refuses to write the treatment plan
data file to either the hard disk or the floppy disk. TCS accesses PLATO's hard disk when a
transfer via the network is required. If such a failure does occur, and the user subsequently
reduces the combined patient and applicator points to a total of 24 or less, then the reduced
data set can be successfully transferred. However, if it is necessary to transfer a treatment plan, to the HDR TCS, that contains a total of more than 24 patient and applicator points, then it will
be necessary to enter either all or part of the treatment plan into the TCS manually.
The sequence of events that led to the erroneous step size change occurred as follows:
1. The treatment plan that eventually produced the erroneous step size was entered
into the TCS manually because of the previously described inability to transfer it
electronically;
2. The radiation oncologist discovered that the dwell times of this treatment plan were
in error, when he reviewed the plan;
IN 99-09 March 24, 1999 3. During the subsequent manual editing of the treatment plan on the TCS, to correct
the erroneous source dwell times, the licensee used the "Tab" key twice in an attempt to
move from one dwell time position to the next. This action inadvertently selected the
step size option;
4. When the previous action had no effect on the selection of the next dwell time
position to be edited, the licensee tried the 'arrow" key twice in an attempt to select the
desired dwell time data. This had the effect of changing the source step size from 2.5 mm to 10 mm;
5. The licensee did not notice the unintended selection of the step size option and
subsequent change to the value of the step size. This change to the step size would
have also resulted in changing the scale and overall length of the "loading grid ruler"
above the channel one dwell positions, as well as the "treatment length value" per
channel;
6. The licensee then used the mouse to select the next dwell time position(s) to be
edited and successfully made the necessary corrections to the source
dwell times.
7. The radiation oncologist reviewed and approved the revised treatment plan without
noticing the altered step size. The patient was subsequently treated using this incorrect
source step size.
The licensee did not discover the error in the step size for the first treatment until one week
later, when it was preparing the treatment plan for the second of the two fractions to be
administered to this patient. When the previous treatment plan was brought up in preparation
for the second treatment, the licensee discovered the increased step size. At this point, the
licensee corrected the erroneous step size and adjusted the written directive, and
corresponding treatment plan, to compensate for the under dosage to the intended treatment
site that occurred in the first fraction.
How did the licensee not notice this step size change? First, in attempting to select the dwell
positions to be edited, by the inappropriate use of the "Tab" and "arrow" keys, the licensee did
not expect this to have any affect on other (unrelated) treatment plan parameters. This
expectation was reinforced by the lack of any cautions or other instructions, in the Nucletron
microSelectron-HDR v1.2X manual, that would indicate otherwise. More importantly, the
licensee expected to see a confirmation message that would have required it to acknowledge
any changes to the treatment plan step size, in accordance with the information on page 4-23 of
the users manual. Secondly, since the licensee did not anticipate that any of the other treatment
plan parameters would change it did not check any parameters other than the source dwell
times on the final printed treatment plan. 7 I
i2 IN 99-09 March 24, 1999 Nucletron has confirmed that this acknowledgment prompt, and corresponding warning
message, only appears when the step size parameter is changed for the first time to a treatment
plan that either: (1) has been electronically transferred from the treatment planning system; or,
(2) has previously had a reference dose entered into TCS. Subsequent changes to the step
size, or changes to the step size in manually entered treatment plans, do not generate the
indicated confirmation box or warning unless you have entered the reference dose on the
previous screen. This behavior is contrary to what would be expected, given the information
provided on page 4-23 of the Nucletron microSelectron HDR users manual, which does not
place any conditions on the expected confirmation prompt from the system. Also, the
descriptions given in the Nucletron TCS manual for the functions of the "Tab" and uarrow* keys
do not include the ability to use these keys for changing treatment plan parameters. Based on
these manual descriptions, the licensee would appear justified in its assumption that no
parameters were inadvertently changed by their inappropriate use of these keys.
This event highlights the importance that, when making changes to treatment plans, licensees
should always be alert to the possibility that other unintended changes can also occur. If such
an unintended change should occur, whether this change were to occur through user error or
system software problems, the potential adverse consequences to the patient remain the same.
Thus, after making any changes to a pre-existing treatment plan, the final treatment plan should
be reviewed for not only for the correctness of the changed parameters but also for its total
overall correctness.
Often device users are the first to discover problems with marketed medical devices. If you
encounter device malfunctions or product problems involving radiation therapy devices or
radiation therapy treatment planning systems, particularly Y2K problems or those which may be
software related, you are strongly encouraged to report such events to MedWatch, the Food
and Drug Administration's (FDA) voluntary reporting program. You may submit voluntary
reports to MedWatch:
by phone at 1-800-FDA-1088;
by FAX at 1-800-FDA-0178;
over the Internet at httP:/ANww.fda.gov/medwatch/; or,
by mailing your report to MedWatch, Food and Drug Administration, 5600
Fishers
Lane (HF-2), Rockville, MD 20857.
You are also reminded that under the Safe Medical Devices Act of 1990, user facilities have
specific mandatory reporting time frames and requirements when they become aware that a
medical device may have caused or contributed to a patient death or serious injury/illness.
al
'J
IN 99-09 March 24, 1999 Questions concerning FDA's mandatory user facility reporting requirements can be directed to
FDA's Center for Devices and Radiological Health, Office of Surveillance and Biometrics, by
calling (301) 594-2735.
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
Technical Contact:
Robert L. Ayres, NMSS
(301) 415-5746 E-mail: rxal@nrc.gov
Attachments:
1. List of Recently Issued NMSS Information Notices
2. List of Recently Issued NRC Information Notices
V.
Attachment 1
March 24, 1999 LIST OF RECENTLY ISSUED
NMSS INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
99-06
1998 Enforcement Sanctions as
3/19/99
All U. S. Nuclear Regulatory
a Result of Deliberate Violations of
Commission licensees.
99-05
99-04
99-03
Inadvertent Discharge of Carbon
Dioxide Fire Protection System
and Gas Migration
Unplanned Radiation Exposures
to Radiographers, Resulting from
failures to follow Proper Radiation
Safety Procedures
Exothermic Reactions Involving
Dried Uranium Oxide Powder
(Yellowcake)
Guidance to Users on the
Implementation of a New
Single-Source Dose-
Calculation Formalism and Revised
Air-Kerma Strength Standard
for lodine-125 Sealed Sources
Deterioration of High-Efficiency
Particulate Air Filters in a
Pressurized Water Reactor
Containment Fan Cooler Unit
3/8/99
3/8/99
1/29/99
1/21/99
1/20/99
All holders of licenses for nuclear
power, research, and test reactor, and fuel cycle facilities
All radiography licensees.
All operating uranium recovery
facilities that produce oxide
powder (U308) (yellowcake)
All medical licensees authorized to
conduct brachytherapy
treatments.
All holders of licences for nuclear
power, research and test reactors;
and fuel cycle facilities.
99-02
99-01
98-33 Regulatory
NRC Regulations Prohibit
Agreements that Restrict or
Discourage an Employee from
Participating in Protected Activities
8/28/98
All holders of a Nuclear
Commission license
98-30
Effect of the Year 2000
Computer Problem on NRC
Licensees and Certificate Holders
8/12/98
All material and fuel cycle
licensees and certificate holders
II
J-
Attachment 2
March 24, 1999 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
99-08 Urine Specimen Adulteration
3/24/99
All holders of operating licenses
For nuclear power reactors and
Licensees authorized to possess
Or use formula quantities of
strategic special nuclear material
(SSNM)
99-07
99-06
99-05
99-04
99-03
99-02
Fire Proctection Preaction
Preaction Sprinkler System
Deluge Valve Failures and
Potenetial Testing Deficiencies
1998 Enforcement Sanctions as a
Result of Deliberate Violation on
NRC Employee Protection
Requirements
Inadvertent Discharge of Carbon
Dioxide Fire Protection System
and Gas Migration
Unplanned Radiation Exposures
to Radiographers, Resulting from
failures to follow Proper Radiation
Safety Procedures
Exothermic Reactions Involving
Dried Uranium Oxide Powder
(Yellowcake)
Guidance to Users on the
Implementation of a New
Single-Source Dose-
Calculation Formalism and Revised
Air-Kerma Strength Standard
for lodine-125 Sealed Sources
3/22199
3/19/99
3/8/99
3/8/99
1/29/99
1/21/99
All NRC licensees
All U.S. Nuclear Regulatory
Commission licensees
All holders of licenses for nuclear
power, research, and test reactor, and fuel cycle facilities
All radiography licensees.
All operating uranium recovery
facilities that produce oxide
powder (U308) (yellowcake)
All medical licensees authorized
to conduct brachytherapy
treatments.
OL = Operating License
CP = Construction Permit
IN 99-09 March 24, 1999 Questions concerning FDA's mandatory user facility reporting requirements can be directed to
FDA's Center for Devices and Radiological Health, Office of Surveillance and Biometrics, by
calling (301) 594-2735.
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
Technical Contact:
Robert L. Ayres, NMSS
(301) 415-5746 E-mail: rxal@nrc.gov
Attachments:
1. List of Recently Issued NMSS Information Notices
2. List of Recently Issued NRC Information Notices
DOCUMENT NAME: G(l:\\):IN99-09.WPD
l FC
l
MS
llTechED
llMSB
L
lDIMNSTl
NAME
RAyres/I
EKraus(FAx)
LWCamper
DACool
l DATE
03/ 05 /99 j
3/8/99
3/17/99
3/17/99
OFFICIAL RECORD COPY
IN 99-XX
March XX. 1999 requirements can be directed to FDA's Center for Devices and Radiological Health, Office of Surveillance and Biometrics, by calling (301) 594-2735.
This information notice requires no specific action nor written response. If you leave
any questions about the information in this notice, please contact the technicat'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
Technical Contact:
Robert L. Ayres, NMSS
(301) 415-5746 E-mail: rxal @nrc.gov
Attachments:
1.
List of Recently Issued NMSS Information Notices
2.
List of Recently Issued NRC Information Notices
DOCUMENT NAGE: G(I:\\):1N99-XX.WPD
l OFA
J/
TechED
MA
1
, D/IS,
NAME
RAyres/ll
EKraus(FAX)
r
[DATE
03/05/99
3/8/99
99
03/ &/99
OFFICIAL RECORD COPY
!