ML20137C265
| ML20137C265 | |
| Person / Time | |
|---|---|
| Issue date: | 12/31/1985 |
| From: | Pettijohn S NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | |
| Shared Package | |
| ML20137C253 | List: |
| References | |
| FRN-52FR36942, RULE-PR-35, TASK-AE, TASK-C505 AC65-1-092, AC65-1-92, AC65-92, AEOD-C505, NUDOCS 8601160258 | |
| Download: ML20137C265 (61) | |
Text
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sO e b AE00/C505 l
I I
f Case Study Report on the I
L Therapy Misadministrations Reported to the NRC Pursuant to 10 CFR 35.42 by the Office for Analysis and Evaluation of Operational Data December 1985
?
l I
Prepared by.
Samuel Pettijohn P
This report documents the results of a study completed to date by the Office for Analysis and Evaluation of Operational Data with regard to particular operating events.
The findings and recommendations may not necessarily represent the final position or requirements of the responsible program
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111 Table of Contents Page EXECUTIVE
SUMMARY
1 1.0 INTR 000CTION....................................................
7 2.0 TELETHERAPY AND BRACHYTHERAPY TREATMENT........................
11 2.1 Teletherapy Treatment.....................................
11 2.2 Brachytherapy Treatment...................................
13 3.0 ANALYSIS OF 18 THERAPY MISA0 MINISTRATIONS REPORTED TO NRC.......
14 3.1 Genera 1...................................................
14 3.2 Teletherapy Misadministrations Involving the Treatment
. Planning Dose Calculations and Treatment Phases of Teletherapy Treatment.....................................
15 3.2.1 Misinterpretation of Physician's Prescription......
15 3.2.2 Dose Calculation Errors............................
17 3.2.3 Other Errors.......................................
18 3.2.4 Summary of Types of Errors and How the Errors Could Have Been Detected...........................
18 3.3 Teletherapy Misadministration Involving Beam Parameter Measurements....................................
21 3.4 Brachytherapy Misadministrations..........................
22 3.5 Present NRC and Industry Efforts Relating to Patient Radiation Safety in Radiotherapy..........................
23
- 3. 5.1 Regul atory Requirements.............................
23
- 3. 5. 2 Indus try Requi rements...............................
24 4.0 FIN 0!NGS........................................................
26
- 5. 0 R E COMME ND AT ION S.................................................
27
6.0 REFERENCES
29 A P P E ND I X A................................................
3 0 l
APPENDIX 8................................................
48 l
l
e' Executive Summary As a result of a number of serious misadministrations involving radiation therapy in the 1970's and to assure the complete and consistent reporting of such events, the NRC promulgated regulations effective November 10, 1980, requiring the reporting by its licensees of diagnostic and therapy mis-administrations involving nuclear medicine studies or radiation therapy."
There are approximately 400 NRC licensees authorized to perform teletherapy treatment, 600 authorized to perform brachytherapy treatment, and 600 authorized to perform radiopharmaceutical therapy treatment.
The Commission's purpose in requiring the submittal of misadministration reports to the NRC is to verify that their causes are properly identified and that licensees implement appropriate corrective actions to prevent recurrence.** If potential generic problems are identified, the Commission notifies other licensees of the generic problem or concerns and assesses the need for additional actions, e.g., changes in regulations to reduce the occurrence of similar and perhaps more serious events.
From November 1980 through July 1984,'NRC licensees reported 27 therapy misadministrations, or about eight per year.
Sixtean of the therapy misadministration involved teletherapy treatment, five involved brachy-therapy treatment, and six involved radiopharmaceutical therapy treatment.
The significance of the therapy misadministrations stem from the fact that each therapy misadministration had the potential to result in severe health effects including shortening the patient's life.
For example, a report by the American Association of Physicists in Medicine (AAPM) on quality assurance in radiation therapy, " Physical Aspects of Quality Assurance in Radiation Therapy" (Ref. 8) states, "The dose response curve in radiation therapy is quite steep in certain cases, and there is evidence that a 7-10% change in the dose to the target volume may result in a significant change in tumor control probability.
Similarly, such a dose change may also result in a sharp change in the incidence and severity of radiation induced morbidity." For 13 of the 27 misadministrations (48%), the patients were overtreated by 20-200% and, in one misadministration case, at least 53 patients were undertreated by s
- The NRC requirement to report these misadministrations was not made an item of "compatability" for Agreement States, however, six Agreement States have adopted similar reporting requirements.
There are about 500 Agreement State licensees authorized to perform teletherapy treatment, about 700 licensees authorized to perform brachytherapy treatment and about 700 licensees authorized to perform radiopharmaceutical therapy treatment.
- Although NRC verifles through the review of misadministration reports and the inspection of licensee facilities that licensees have proposed and implemented corrective actions; there is no regulatory basis to enforce i
the corrective action that licensees voluntarily propose or implement.
. 10-15%.
Further evidence of the potential for adverse health effects is medical consultant reports concerning patients in two of the reported misadministrations.
These reports stated that the two patients have a high probability of developing long-term health effects as a result of the misadministrations.
, Additional factors that weigh on the significance of the reported misadminis-trations are that:
The types of errors that led to most of the misadministrations are similar to one another, indicating that there may be a significant potential for these types of errors to occur and thus to continue to occur in the future.
The data highlight that many misadministrations may have been detected by licensees during such routine medical activities as patient chart reviews; however, the errors appeared to have been detected more by chance than by design.
That is, in 14 out of 16 teletherapy mis-administrations (88%), the errors were not detected before at least 70% of the treatment had been performed.
Three of the misadministration cases involved a substantial degradation to the protection of public health and safety as defined in the Commission's criteria for abnormal occurrences related to misadmints-trations and thus were reported in the Quarterly Report to Congress on Abnormal Occurrences.
The 16 teletherapy misadministrations reported to NRC from November 1980 to July 1984 came from 400 or so NRC licensees.
The annual licensee error rate (misadministrations/ licensee / year) is about 1 x 10 2, the rate ranging from a low of 2.5 x 10 3 (1982) to 3 x 10 2 (1984).* Since hospital procedures are probably reasonably consistent, and professional staffs reasonably invarient, the annual licensee error rate describes the probable error rate for all NRC licensees.
There were 68 patients over or undertreated in the 16 teletherapy misadminis-trations reported to NRC.
The error rate per patient amounts to 2 x 10 4**
or about the same error rate as calculated for diagnostic misadministrations, 80ata from which error rates could be calculated were not available for brachytherapy and radiopharmaceutical therapy.
- This error rate is calculated based on data contained in the summary of results from the Fourth Facilities Master List 50rvey conducted by the American College of Radiology (ACR) " Patterns of Care" Study (Ref. 1).
The survey showed that in 1980 there were 820 cobalt-60 teletherapy machines in use in the United States.
The survey also showed that about 227 new patients are treated per year per machine. This gives about 177,514 new patients treated per year.
Since NRC regulates only about half of the therapy facilities in the United States (23 States are regulated by NRC), about 88,757 patients per year or about 310,649 patients for the approximately 3-1/2 year period from November 1980 through June 1984 were treated in NRC-licensed facilities.
- . i.e., 6 x 20 2.to 1 x 10 4 If one looks only at diagnostic misadministrations in which the patient received too much or too little radioisotope, the error rate for that type of misadministration is about 3 x 10 s or a factor of 100 smaller than the therapy misadministration rate.
The smaller rate may result from the requirement for licensees to measure the diagnostic dose of radioisotopes before they are administered to patients, an action that can be interpreted as independent verification.
Despite the fact that therapy misadministrations have a much higher probability of resulting in a large unintentional radiation dose to patients than do diagnostic misadministrations,* there is no comparable requirement for therapy licensees to independently verify the accuracy of patient doses prior to administration (e.g., independent verificaticn of dose calculations).
Consequently, based on the potential for theracy misadministrations to result in severe health effects including death, the types of errors, the potential for improved detection of errors, and the public health and safety implica-tions, a detailed analysis of the reported misadministrations was undertaken as embodied in this report.
We believe this decision to be consistent with the guidance set forth in Section I, Paragraph 2, of the medical policy statement, "The NRC will regulate the radiation safety of patients where justified by the risk to patients and where voluntary stand:rds or compliance with these standards are inadequate."
This case study is a detailed review of the 16 teletherapy misadministrations and two brachytherapy misadministrations reported by 17 hospitals to NRC through July of 1984.
The remaining nine events, three brachytherapy events and six radiopharmaceutical events, involved procedural problems, equipment problems, or failure of licensees to follow NRC requirements.
Because of the specific nature of these nine misadministrations, they were not analyzed as part of this study and no recommendations regarding them are provided.
All nine events are, however, discussed in Appendix B of this report.
Each therapy misadministration event involved the administration of a radiation dose that differed from the prescribed dose by greater than 10%
(10 CFR 35.42(f)) and each was caused by human error.
Except for one case, the misadministrations involved only one patient.
The exception involved 53 patients over a three year period.
This misadministration resulted from an error in the measurement of the transmission of cobalt-60 radiation through a wedge filter used as an accoutrement to the teletherapy machine.
- Diagnostic procedures typically involve the administration of a millicurie amount of a radioisotope that results in a radiation dose to the patient of less than a rad.
The administration of a typical diagnostic dose of a radiopharmaceutical even 100% greater than the prescribed diagnostic dose would result in a total radiation dose to the patient of less than 10 rads.
e
. The root causes that led to the teletherapy misadministrations involving single patients were; misinterpretations of the therapy physician's prescription; arithmetic errors in dose calculations; use of the wrong data in dose calcula-tions; misreading of treatment time; and arithmetic errors in adding therapy segments.
The root cause leading to both brachytherapy misadministrations was the loading of the wrong activity sources into the source applicator.
Corrective actions identified by licensees for the teletherapy misadminis-trations included independent verification of patient dose calculations and improved patient treatment chart checks.
The proposed corrective action for the brachytherapy misadministrations was independent verification of the activity of brachytherapy sources loaded into source applicators.
The existing NRC regulations do not specifically address patient radiation safety as it relates to ensuring the accuracy of dose calculations and/or delivery of treatment.
However, the NRC policy statement on the regulation of the medical uses of radioisotopes serves as further guidance in interpreting NRC's role in regulating medical uses of radioisotopes, and provides a basis for regulating patient radiation safety.
The three salient points of the policy statement are:
The NRC will continue to regulate the medical uses of radioisotopes as necessary to provide for the radiation safety of workers and the j
general public.
The NRC will regulate the radiat. ion safety of patients where justified by the risk to patients and where voluntary standards, or compliance with these standards, are inadequate.
The NRC will minimize intrusion into medical judgments affecting patients and into other areas traditionally considered to be a part of the practice of medicine.
Medical professional groups and government agencies other than the NRC are involved in promoting quality assurance programs in medical facilities performing radiation therapy.
Independent verification of dose calculations, source activity (brachytherapy sources) and measurements relating to patient dose calculations, and the adequacy of patient chart reviews are normally included in the recommendations made by these groups for quality assurance programs at medical facilities performing therapy procedures using radio-isotopes.
Further, such activities have been determined to be appropriate and warranted in order to help prevent the recurrence of misadministration events, and thus, are standard practice in a number of facilities.
However, adherence by radiotherapy facilities to such recommended practices is now voluntary.
There are no generally accepted standards that address the verification of patient dose calculations, or the quality of patient chart reviews.
The findings contained in this report are:
4 (1) Of the 16 teletherapy misadministrations reviewed in this study, 12 could have been prevented by improved patient chart reviews or in most cases by independent verification of patient dos calculations.
In
. addition, one of the 16 misadministrations could have been prevented by independent verification of measurements made in calculating wedge filter correction factors; and one misadministration could have been prevented by independent verfication of the tumor depth measurements.
Such actions were identified by licensees as the appropriate corrective action for the misadministration events that have occurred.
(2) The two brachytherapy misadministrations could have been prevented by licensee personnel independently verifying that correct brachytherapy sources were loaded into the source applicator prior to, or concurrent with, implanting the brachytherapy sources.
Such independent verifi-cation was the appropriate corrective action identified by the licensees in the case of the two misadministrations.
(3) The teletherapy misadministration that involved 53 patients over three years involved human error in measuring the transmission of cobalt-60 radiation through a wedge filter.
The regulations issued in November 1980 that require teletherapy machine calibration (10 CFR 35.21) do not require that correction factors for beam modifiers such as wedge filters be verified during the annual calibration of the teletherap machine.
(4) Adverse patient reactions were factors in prompting licensee personnel to review treatment plans in only three of the misadministration cases despite the fact that in at least six cases treatment fractions exceeded the prescribed fraction by over 50L
' Licensee personnel did not appear perceptive in associating adverse patient reactions (which occurred in at least two misadministration cases) or in noting excessive timer settings as possible indicators of misadministrations.
(5) Although professional medical groups involved with radiotherapy and related government agencies encourage quality assurance programs in radiotherapy facilities, no government agency or nongovernmental accrediting body requires that radiotherapy facilities have quality assurance programs that conform to the programs recommended by professional medical groups.
Thus, many facilities may not have quality assurance programs that are consistent with recommendations of medical professional groups involved with radiation therapy.
(6) Our analysis indicates that Agreement State licensees are likely to experience the same frequency and types of errors found for NRC licensees.
As a result, the recommendations for corrective actions contained in this report are applicable to Agreement State licensees as well as NRC licensees.
The recommendations contained in this report are:
(1) That the Office of Nuclear Material Safety and Safeguards (NMSS) should communicate the information contained in this report to the affected licensees.
. (2) That the Office of Nuclear Material Safety and Safeguards (NMSS) should consider the following actions in regard to establishing qual #ty assurance requirements for radiotherapy facilities
- licensed by NRC:
-l Contact appropriate professional organizations to encourage and support the initiation of a voluntary, industry-directed physical quality assurance program for radiotherapy facilities.
We believe that the commitment of the professional organizations in this regard should be assessed by the NRC and a conclusion reached as to the effectiveness of the voluntary program within two years.
If substantial progress toward completion of the voluntary program, including a final completion date, has not been demonstrated at the end of two years, we recommend that NMSS initiate the necessary studies to determine whether a rulemaking is justified to require
'that radiotherapy facilities. licensed by NRC have quality assurance programs to insure the accuracy of patient doses.
The program should include such things as:
independent verification of patient dose calculations and independent verification of the activity of brachytherapy sources before the sources are implanted.
The voluntary quality assurance program should contain at least the elements outlined above.'
(3) 10 CFR Part 35.21 should be amended to include the calibration of beam modifiers such as wedge filters, shaping filters, trays, etc.
(4)
In addition, to the extent that th*e NRC implements recommendation 3, the action should be made an item of compatibility for Agreement States.
- A comprehensive quality assurance program in radiation therapy has both a clinical component and a physical component.
The clinical component includes such things as clinical evaluation of the patient, therapeutic decision (e.g., curative, or pallative treatment, and choice of treatment modalities).
The physical component includes such things as dosimetry, treatment planning, treatment machines and simulators, and radiation safety.
1.0 INTRODUCTION
The Nuclear Regulatory Commission (NRC) regulates certain aspects of the uses of reactor produced radioisotopes in nuclear medicine and therapeutic radiology.
Nuclear medicine is defined as that specialty in the practice of medicine dealing with the diagnostic, therapeutic (exclusive of sealed sources),
and investigative use of radionuclides.
Therapeutic radiology is that branch of radiology which deals with the therapeutic application of ionizing radiation including roentgen and gamma rays as well as particulate radiation from what-q ever source, including artificially and naturally radioactive materials as well as X-ray generators and particle accelerators.* As a result of a number of serious misadministrations involving radiation therapy in the 1970s, and to assure the complete and consistent reporting of such events, the NRC promul-gated regulations (10 CFR 35.41 through 35.45) to require the reporting of diagnostic and therapy misadministrations** involving nuclear medicine studies or radiation therapy.
The regulations which became effective on November 10,'1980, define a misadministration to mean the administration of:
(a) a radiopharmaceutical or radiation from a sealed source other than the one intended; (b) a radiopharmaceutical or radiat. ion to the wrong patient;-
(c) a radiopharmaceutical or radiation by a route of 'dministration a
other than that' intended by the prescribing physician; (d) a diagnostic dose of a radiopharmaceutical differing from the prescribed dose by more than 50%;
(e) a therapeutic dose of a radiopharmaceutical differing from the prescribed dose by more than 10%; or (f) a therapeutic radiation dose from a sealed source such that errors in the source' calibration, time of exposure, and treatment geometry result in a calculated total treatment dose differing from the final prescribed total treatment dose by more than 10%.
- The Atomic Energy Act of 1954, as amended in 1974, limits the NRC's regula-tion of radioactive materials to reactor produced isotopes.
- Diagnostic misadministration, as used in NRC regulations, refers to the misadministration of radioisotopes in nuclear medicine studies such as brain scans and bone scans.
Therapy misadministration as used in NRC regulations refers to the misadministration of radiation from cobalt-60 teletherapy or radioisotopes in radiation therapy.
s
. Items (a), (b), (c), (e) and (f) apply to theroy misadministrations, and (a),
(b), (c) and (d) apply to diagnostic misadministrations.* The NRC requirement to report these misadministrations was not made an item of " compatibility" for Agreement States; however, six Agreement States have adopted similar reporting requirements.
From November 1980 through July 1984, NRC licencees reported 27 therapy i
misadministrations, or about eight per year.
Sixteen of the therapy misadministrations involved teletherapy treatment, five involved brachy-therapy treatment, and six involved radiopharmaceutical therapy treatment.
The significance of the therapy misadministrations stem from the fact that each therapy misadministration had the potential to result in severe health effects including shortening the patient's life.
For example, a report by the American Association of Physicists in Medicine (AAPM) on quality assurance in radiation therapy, " Physical Aspects of Quality Assurance in Radiation Therapy." (Ref. 8) states, "The dose response curve in radiation therapy is quite steep in certain cases, and there is evidence that a 7-10% change in the dose to the target volume may result in a significant change in tumor control pr'bability.
Similarly, such a dose change may also result in a sharp change o
in the incidence and severity of radiation induced morbidity.,"
For 13 of the 27 misadministrations (48%), the patients were overtreated by 20-200% and,
,in one misadministration case, at least 53 patients were undertreated by 10-15%.
Further evidence of the potential for. adverse health effects is medical consultant reports concerning patients in two of the reported misadministrations.
These reports stated that the two patients have a high probability of developing long-term health effects as a result of the misadministrations.
Additional factors that weigh on the significance of the reported misadminis-trations are that:
The types of errors that led to most of the misadministrations are similar to one another, indicating that there may be a significant potential for these types of errors to occur and thus to continue to occur in the future.
The data highlight that many misadministrations may have been detected by licensees during such routine medical activities as patient chart reviews; however, the errors appeared to have been detected more by chance than by design.
That is, in 14 out of 16 teletherapy mis-l administrations (88%), the errors were not detected before at least j
70% of the treatment had been performed.
l Three of the misadministration cases involved a substantial degradation to the protection of public health and safety as defined in the Commission's criteria for abnormal occurrences related to misadminis-trations and thus were reporteJ in the Quarterly Report to Congress on Abnormal Occurrences.
l
- AE00's study of misadministrations as embodied in this report is concerned with therapeutic misadministrations although several references are made in the report to diagnostic misadministrations.
. The 16 teletherapy misadministrations reported to NRC from November 1980 to July 1984 came from 400 or so NRC licensees.
The annual licensee error rate (misadmin'istrations/ licensee / year) is about 1 x 10 2, the rate ranging from a low of 2.5 x 10 3 (1982)-to 3 x 10 2 (1984).* Since hospital procedures are probably reasonably consistent, and professional staffs reasonably invarient, the annual licensee error rate describes the probable error rate for all NRC licensees.
There were 68 patients over or undertreated in the 16 teletherapy misadminis-trations reported to NRC. The error rate per patient amounts to 2.x 10 4**
or about the same error rate as calculated for diagnostic misadministrations, i.e., 6 x 10 2 to 1 x 10 4 If one looks only at diagnostic misadministrations in which the patient received too much or too little radioisotope, the error rate for that type of misadministration is about 3 x 10.s or a factor of 100 smaller than the therapy misadministration rate.
The smaller rate may result from the requirement for licensees to measure the diagnostic dose of radioisotope before they are administered to patients, an action that can be interpreted as independent verification.
Despite the fact that therapy misadninistrations have a much higher probability of resulting in a large unintentional radiation dose to patients than do diagnostic misadministrations,*** there is no comparable requirement for therapy licensees to independently verify the accuracy of patient doses prior to administration (e.g., independent verification of dose calculations).
Consequently, based on the potential for therapy misadministrations to result in severe health effects including death, the types of errors, the potential for improved detection of errors; and the public health and safety impli-1
- Data from which error rates could be calculated were not available for brachytherapy and radiopharmaceutical therapy.
- This error rate is calculated based on data contained in the summary of results from the Fourth Facilities Master List survey conducted by the American College of Radiology (ACR) " Patterns of Care" Study (Ref. 1).
The survey showed that in 1980 there were 820 cobalt-60 teletherapy machines in use in the United States.
The survey also showed that about 227 new patients are treated per year per machine.
This gives about 177,514 new patients treated per year.
Since NRC regulates only about half of the therapy facilities in the United States (23 States are regulated by NRC), about 88,757 patients per year or about 310,649 patients for the approximately 3-1/2 year period from November 1980 through June 1984 were treated in NRC-licensed facilities.
- Diagnostic procedures typically involve the administration of a millicurie amount of a radioisotope that results in a radiation dose to the patient of less than a rad.
The administration of a typical diagnostic dose of a radiopharmaceutical even 100% greater than the prescribed diagnostic dose would result in a total radiation dose to the patient of less than 10 rads.
i
o
. cations, a detailed analysis of the reported misadministrations was undertaken as embodied in this report. We believe this decision to be consistent with the guidance set forth in Section I, P6ragraph 2, of the medical policy statement, "The NRC will regulate the radiation safety of patients where justified by the risk to patients and where voluntary standards or compliance with these standards are inadequate."
As used in NRC regulations, radiation therapy treatment involves the use of ionizing radiation for treatment of malignant neoplasia and several other diseases such as hyperthyroidism and cardiac dysfunction. The National Cancer Institute, however, defines radiation therapy as a clinical specialty dealing with the use of ionizing radiation for the treatment of patients with malignant neoplasia (Ref. 3).
In this case study, the use of the term " radiation therapy" is consistent with the NRC regulations.
There are three principal types of radiation therapy:
teletherapy (radiation treatment administered by an external radiation source such as cobalt-60, linear accelerators, etc.);* brachytherapy (radiation treatment administered by a sealed source, internal to the body, such as small " needles" or " seeds" containing cesium-137, iodine-125, or iridium-192 sources contained in ribbons); and radiopharmaceutical th'erapy (radiation treatment administered orally or through injection of an unsealed source such as iodine-131 or phosphorus-32).
There are approximately 400 NRC licensees authorized to perform teletherapy treatment, 600 authorized to perform brachytherapy treatment, and 600 licensees authorized to perform radiopharmaceutical therapy treatment.
In addition to the NRC licensees authorized to perform radiation therapy, about l
500 Agreement State licensees are authorized to perform teletherapy treatment, about 700 to perform brachytherapy treatment, and about 700 to perform radio-pharmaceutical therapy treatment.
The Commission's purpose in requiring the submittal of misadministration reports to the NRC is to verify that their causes are properly identified and that licensees implement appropriate corrective action to prevent their recurrence.** If potential generic problems are identified, the Commission l
l
- Any regulation of radiation therapies that use linear accelerators, or X-ray l
equipment is done by the individual States. As a result, misadministrations involving these types of radiation therapy do not come within NRC's reporting requirement. Any reporting requirements for these types of therapy would be those imposed by the individual States.
- Although NRC verifies through the review of misadministration reports and the inspection of licensee facilities that licensees have proposed and implemented ccrrective actions, there is no regulatory basis to enforce the corrective action that licensees voluntarily propose or implement.
l l
notifies all licensees and assesses the need for additional action, e.g.,
changes in regulations to reduce the occurrence of similar and perhaps more 2
serious events.
Written reports of misadministrations are submitted by licensees to the appropriate NRC Regional Office. The Regional Office reviews a licensee's misadministration report and either performs a special inspection to investigate the misadministration or includes a review of the misadministration in the next scheduled inspection of the licensee.
In.the case of therapy misadministrations, the Regional Office will normally make a determination of whether to have a medical consultant assess the effects of the misadminis-tration on the patient.* The NRC Offices of Inspection and Enforcement (IE) and Nuclear Material Safety and Safeguards (NMSS) receive copies of licensee misadministration reports and review them for generic problems. The NRC Office for Analysis and Evaluation of Operational Data (AE00) also receives copies of the reports, reviews them for generic problems, prepares abstracts, and enters 4
pertinent data into a computerized data base.
A review of the brachytherapy and radiopharmaceutical therapy misadminis-trations repor.ted to NRC showed that:
three of the five brachytherapy events resulted from procedural or equipment problems; two of the six radio-
~
pharmaceutical events resulted from procedural problems; and the four radio-pharmaceutical events resulted from fai. lure of licensees to assay patient doses before administration as presently required by NRC. Because of the nature of these events, no recommendations are provided relating to these nine misadministrations.
Further discussion of these nine events is contained in Appendix B of this report. The remainder of this report is a detailed review of the remaining 16 teletherapy misadministrations and two brachytherapy misadministrations reported to NRC through June of 1984.
Section 2 discusses radiation therapy treatment; Section 3 is an analysis i
of the 16 teletherapy misadministrations and two brachytherapy misadminis-trations; Section 4 gives the findings of the ~ tudy; and Section 5.contains s
recommendations from the study. Appendix A contains a summary description of the 18 misadministrations discussed in Section 3; and Appendix B provides
.a discussion of the nine other therapy misadministrations reported to NRC.
2.0 TELETHERAPY AND BRACHYTHERAPY TREATMENT 2.1 Teletherapy Treatment Teletherapy treatment involves delivering a radiation dose to a tumor by directing a beam of ionizing radiation from an external source toward the tumor region. The prescribed radiation dose is delivered in a series of treatments
- Medical consultants were involved in evaluating the effect of the mis-administration on the patient in about 5 of the 27 cases reported.
---w v
- FIGURE 1 SIMPLIFIED FLOWCHART OF RADIATION. THERAPY CLINICAL SERVICE (Ref. 3)
Patient Ra cfiation Therapy Flow -
.As
" Program Clinical Evaluation Pathobiology of Tumor l
DX Work Up Analysis of Stagin9 Regional!!aeds 4
In Cancer Care Thetepe utic Decision a
Cure intera ction with RX Go,als ( Palliation
~
Prof e ssienal 0:hsr Caricer Care In t e ra citons
Activities in the
' Patient Care Choice of Tntrapy Regico i-Con:Inuing Modalities Education 4
- Research Tumor Locallaation I
Patient Contour i
j Ta rget Volume Definition Equipment Sensitive Organs Catitration Definition.
and Tests 4
/
Treatment Planning Simulation Records'. }
Records:
- Equipment Computation of Beams
- Pa:ient Analysis of A! ernatives
(
- Faciti:y Choice o! F.X Plan Cc:.;ensa.tsrs I
PrFg' ram Films 1or Vari lica:lon t== dill:ailon I
g Cosimetry Precedures Shieldin;'E!o:ks -
I 4
Mc.: Ids-1.'. asks Treatment V
Oose Time Calculations Dosimet.y Checks Repositioning Locall:atien Films 4
Periodic Evaluauon
/
---of Tumor Response and Supportive Tolerance of Patient Core During Treatment s
+
Fo11ove Up Evalu alion L.
.v From: " Criteria for Radiation Oncology in Multidiciplinary Cancer Management," Report to the Director of the National Cancer Institute of Health by the Committee for Radiation Oncology Studies, February 1981.
(fractions), usually one per weekday for several weeks.
Teletherapy treatment is a complex procedure that involves several professionals and many steps (see Fig. 1); consequently, there are many opportunities for errors.
- However, because teletherapy treatment normally involves a series of treatments or dose fractions administered over a period of days or weeks, the opportunity exists to detect and possibly adjust for errors before they result in misadminis-trations (i.e., once an error has been detected, the subsequent dose fractions may be adjusted to compensate for the error in treatment dose).
Most treatment regimes are modified after weekly examination of the patient and there is usually a weekly review conference about each patient's treatment. One method of modifying treatment regimes as well as detecting errors is to have important calculations and measurements (e.g., dose calculations, tumor depth measurements, machine calibration measurements) checked by a qualified individual who did not do the original mcasurments or calculations.
Another method of treatment modification and detecting errors is through periodic reviews of the patient treatr.ent chart.
Each institution generally develops its own system or method of describing and recording the treatment on individual patient charts, but the function of the chart is essentially the same in all cases.
Reviews of the treatment chart are performed to insure that the patient's progress is monitored, and that any needed changes in the treatment procedures are determined and implemented.
Teletherapy treatment typically involves linear accelerators or teletherapy machines containing cobalt-60.
However, only cobalt-60 teletherapy machines are licensed by the NRC and, therefore, only misadministrations involving cobalt-60 teletherapy machines are required to be reported to NRC.
Linear accelerators are licensed or registered by individual States; therefore, any reporting requirements for misadministrations involving linear accelerators are those imposed by the individual States.
l Regulatory Guide, " Guide for the Preparation of Applications for Licenses in
~
^
Medical Teletherapy Programs," dated March 1982, contains instructions for laplicantsrequesting.teletherapylicenses.
Although this Regulatory Guide.
p has been issued only in draft form, it provides a description of an NRC staff position on licensing cobalt-60 teletherapy treatment.
2.2 Brachytherapy Treatment Brachytherapy treatment involves the use of sealed radioactive sources placed in the tumor region for a prescribed period of time (intracavitary or inter-stitial implants).
While brachytherapy treatment may be performed in conjunction with teletherapy treatment, brachytherapy treatment typically I
does not involve a series of treatments.
Brachytherapy treatment involves essentially the same general steps as outlined in Figure 1 for teletherapy treatment; e.g., therapeutic decision, tumor localization, treatment planning, etc.
Brachytherapy treatment can involve several sources of different activity for a particular patient versus a single source contained in a teletherapy machine for teletherapy treatment.
Brachytherapy treatment may involve the use of sealed sources of radium-226, cesium-137, iridium-192, or iodine-125.
Some brachytherapy implants are permanent implants; e.g., iodine-125 seeds used in somt procedures.
- However, most procedures involve implanting the sources into the. tumor or in a body cavity for a specific period of time, after which the sources are removed.
o
. The use of cesium-137, iodine-125, and iridium-192 brachytherapy sources is licensed by the NRC.
The use of radium-226 sources is not licensed by NRC (radium-226 sources are being replaced by cesium-137 sources).
Any licensing or registration of radium-226 sources still in use is done by individual States.
Regulatory Guide 10.8 (Ref. 4) describes, among other things, the type of information the NRC staff needs for review of license applications for brachytherapy treatment.
3.0 ANALYSIS OF 18 THERAPY MISADMINISTRATIONS REPORTED TO NRC 3.1 General The 16 teletherapy misadministrations and two brachytherapy misadministratio~ns analyzed in this section were reported by 17 hospitals.* Each involved the administration of a therapy dose of radiation that differed from the prescribed dose by greater than 10% (10 CFR 35.42(f)), and each was caused by human error.
Table 1 is a tabulation of the percent difference in prescribed and admini-stered doses for the reported misadministrations.
All of the misadministrations involved only one patient, except one which involved 53 patients over a three year period.
This misadministration resultad from an error in the measurement of the transmission of cobalt-60 radiation through a wedge filter used as an accoutrement to the teletherapy machine.
The root causes that led to the teletherapy misadministrations involving single patients were:
misinterpretations of the therapy physician's prescription; arithmetic errors in dose calculations; use of the wrong data in dose calculations; misreading of treatment time; and arithmetic errors in adding therapy segments.
The root cause leading to both brachytherapy misadministrations was the loading of the wrong activity source into the source applicator.
_ Corrective actions identified by licensees for the teletherapy misadminis-trations included independent verification of patient dose calculations and improved patient treatment chart checks.
The corrective action for the brachytherapy misadministrations was independent verification of the activity of brachytherapy sources loaded into source applicators.
While the adverse health effects that may result from these therapy mis-administrations could not be quantified for most of the cases, an evaluation of the health effects of the misadministrations was donc by the licensee or l
an NRC medical consultant.
The evaluations for two of the cases indicate l
that there is a high probability of severe long-term health effects for the patients affected.
Three of the cases (1, 8, 9)** involved a substantial degradation to the protection of public health and safety as defined in the Commission's Criteria for Abnormal Occurrences related to misadministration and, thus, were reported in the quarterly report to Congress as Abnormal Occurrences.
l
- 0ne hospital reported two misadministrations.
- These numbers refer to the listing in Table 1; these numbers are also used in Appendix A.
i l
o e, The subsections.which follow contain an evaluation of several factors related to the reported misadministrations:
the type of misadministration, the cause 4
of the mi'sadministration, factors contributing to the detection of the i -
misadministration, and indicators that might have alerted the licensee to a pending or actual misadministration.
In addition, Appendix A contains a tabulation of these factors and a brief description of each of the 16 tele-therapy misadministrations and two brachytherapy misadministrations.
TABLE i Percent Differences in Prescribed and Administered Doses for the Reported Misadministrations Percent Difference Misadministration #
Administered Dose / Prescribed Dose 1
-10% to -15% (53 patients) 2 N/A (wrong part of body) 3 11.5%
4 25%
5 14%
~
6 36%
7 33%
8 70%
9 60%
4 10 20%
11 60%
12 45%
13 60%
14 100%
15 11%
16 37%
f 17 21-37%
18 200%
3.2 Teletherapy Misadministrations Involving the Treatment Planning Dose Calculations and Treatment Phases of Teletherapy Treatment i
Of the 16 teletherapy misadministrations, all except one involved the treatment planning dose calculations and treatment phase of teletherapy treatment.
Twelve resulted from errors associated with the dose calculation phase of treatment planning.
That is, either the physician's prescription was misinterpreted (2, 12, 13, 14, 16), the wrong data were used in the dose calculation formula (6, 7, 9, 11), or an arithmetic error was made in the dose calculation (3, 10, 15).
Three of the other four misadministrations involved:
errors during the treatment Phase (1, 4, 5, 8) such as, misreading of the handwritten treatment time (1.39 read as 1:89) (4); an arithmetical error in the addition of therapy segments (5); and a failure of the therapy physician to record a change in the treatment plan on the radiotherapy treatment sheet (8).
The only misadministration that did not occur during planning or treatment involved the use of an erroneous wedge block correction factor.
This misadministration is discussed in section 3.3.
i v,.
+
.-m--.--..-,.r
--c.~
.ry----
o,
.. 3.2.1 Misinterpretation of Physician's Prescription
-The five misadministrations involving misinterpretation of the physician's prescription (2, 12, 13, 14, 16) involved the prescribed tumor dose per treatment.
Two of these misadministrations (12 and 13) were very.similar.
They involved treating brain tumors using two treatment fields--laterally opposed in one case and front and side in the other case.
In calculating the timer setting, the physicist or dosimetrist used the prescribed total dose per treatment field for the treatment dose per field.
This resulted in a tumor treatment dose twice the prescribed dose.
The dose prescriptions were clear in both cases. The errors apparently resulted from confusing the dose per treatment fraction with the dose per tumor field.
- In misadministration 13, the final dose calculations were checked by a second individual before treatment began.
This check apparently consisted only of verifying the arithmetic accuracy of the calculations.
Thus, the error was not detected.
Even though the patient was being treated at twice the dose per fraction there were no adverse patient reactions to alert therapy personnel.
The error was detected during a routine patient treatment chart review, but was not discovered until 16 of 20 prescribed treatments had been administered.
In misadministration 12, the patient did experience an adverse reaction (severe erythema) to the treatment.
As a result, the dose calculations were checked, for arithmetic accuracy; however, the e'rror was not detected.
The administered dose was reduced from 200 rads per treatment field to 150 rads per treatment field (the prescribed dose was 100 rads per treatment field).
After noting an increasing severity of the erythema, the dose calculations were again reviewed and the error finally was detected after 33 of the prescribed 36 treatments had been administered.
i.
A third misadministration in which the physician's order was misinterpreted (14) also involved treatment to two tumor fields--anterior and posterior pelvic treatment.
The error in this case resulted from confusion regarding treatment dose information given in a verbal prescription (600 rads times three treatments), with treatment dose information given in a later written prescription (300 rads times five treatments).
The administered treatment was i
600 rads times five treatments, which was twice the prescribed dose rate.
The verbal prescription was apparently given by the therapy physician to a therapy technologist while the technologist was simulating the patient for another therapy.
The technologist was told to simulate the patient for the pelvic therapy in the event the patient's physician ordered the treatment.
The dose verbally prescribed was 600 rads times three treatments. The technologist made dose calculations based on this prescription which were checked for arithmetic accuracy by a physicist.
The same physicist later received a verbal prescription from the therapy physician for the therapy prescribing 300 rads times five treatments.
The physicist wrote down the prescription and had the therapy physician ~ sign it.
The physicist, not realizing that the technologist's dose calculations that he had reviewed (600 rads times three 1
a.
. i treatments) were for a different prescription than the written prescript' ion (300 rads times five treatments) he received, transcribed the information from i
the dose calculation sheet onto the patient's treatment sheet.
Before the treatment began one of the therapy technologists questioned the physicist as to l
whether the machine on-time was excessively long, indicating possible over-i treatmerit of the_ patient. The physicist reviewed the physician's prescription with the technologist and concluded that the time was correct.
The misadministration was not discovered until about a month after the patient received the treatment, when the patient's treatment plan was reviewed because the patient complained of discomfort.
The other two misadministrations in this group involved the misinterpretation of the last three of 30 prescribed treatments as 500 rads times three treatments instead of 500 rads in three treatments (16); and the treatment of the left breast instead of treatment of the right breast (2).
In the first case the misadministration was not detected until after completion of the therapy from a patient chart review.
In the second case, one treatment was made before the therapist, who was present during the treatment, realized that 4
the patient had been set up for treatment to the wrong breast.
3.2.2 Dose Calculation Errors There were seven misadministrations due to this type of error involving dose calculation.
Four misadministrations resulted from the wrong data used for dose calculations, and three misadministrations resulted from arithmetic errors.
j (1) Wrong data used in the dose calculation formula (6, 7, 9,11):
In two cases (6, 7), the incorrect tumor depth was used in calculating the treatment dose.
In one case, the tumor depth had been measured incorrectly.
This resulted in an administered 4
dose of 5570 rads whereas the prescribed dose was 4070 rads.
4 The patient was being remeasured during a routine follow-up visit when the error was discovered.
In the other case the correct tumer depth apparently had been determined, but had been entered erroneously on the patient's chart.
This resulted in an admini-l-
stered dose of 6000 rads whereas the prescribed dose was 4500 rads.
1 The error was detected during a routine patient chart review.
l In one case (9), erroneous data generated by one computer program was used in another unrelated computer program. The licensee was using a relatively new computer treatment planning system and indicated to NRC that it was aware of the need to verify the computer calculations by hand.
The prescribed dose for the treatment was 2000 rads; however, the patient was administered a dose of 3200 rads.
The misadministration was detected when hand calculations revealed the error. The hand calculations were made after the five prescribed therapy I
treatments had been completed.
i
't
- In another case (11), the dosimetrist used a dose rate factor for one machine from a table for a different machine.
The tables for several different machines were kept in the same book.
The error resulted in a treatment dose rate of over 50% of the prescribed treatment dose rate and a total treatment dose of 8500 rads, whereas the prescribed dose was 6500 rads.
The error was detected while the dosimetrist was revising the patient's treatment plan, but not until 27 of 36 prescribed treatments had been completed.
(2) Arithmetic error made in dose calculations (15, 3,10):
One case (15) involved brain therapy using opposed lateral fields similar to misadministrations 13 and 14.
In this instance, an arithmetic error was made in the dose calculation.
The calculations were originally done by a technologist and were checked by a physicist, but the enror was not detected.
Hospital records indicated that the physicist reviewed the treatment chart four times at two-week intervals a's required by the hospital's procedures without detecting the error.
The administered treatment dose rate was approximately 50%
greater than the prescribed dose rate (308 rads per fraction vs 200 rads per fraction).
The patient exhibited an unduly severe scalp reaction, prompting a review of the patient's treatment plan.
An initial review by the same physicist who had. checked the original, calculations did not detect the error.
A. review of the treatment plan by the chief technologist about three weeks later revealed the error. Twenty-two of the prescribed 30 treatments had been completed.
The other two misadministrations (3, 10) involved a multi-plication error in calculating machine nn-time and an error in converting from rads per day to machine on-time.
In both cases, the errors were detected by routine patient chart reviews.following completion of the therapy.
3.2.3 Other Errors Three of the misadministrations involving teletherapy machines resulted from random errors:
an error of misreading the length of time for machine operation (1.39 minutes was read as 1.89 minutes) was detected after 11 of 12 scheduled treatments had been completed (4); an arithmetic error made in the addition of therapy segments (5); and the failure of the therapy physician to record a change in the treatment plan on the radiotherapy treatment sheet (8).
Misadministrations 5 and 8 were detected by a patient treatment chart review after completion of the therapy.
3.2.4 Summary of Types of Errors and How the Errors Could Have Been Detected Table 2 lists the types of errors that caused 15 of the teletherapy mis-administrations and indicates whether independent verification of dose calcu-lations or timely chart reviews could have dc.tected the error and prevented
]
e-
. ^ ' TABLE 2'
~
Summary of Types of Errors that Caused 15 of the 16 Teletherapy Misadmini~ trations Reported to NRC s
Error in Independent Timely and Treatment Verifleation of Improved Misadmin-Planning /
Error in Dose Calculations Chart Review istration.
Dose Treatment /
Could Have Could Have Number
- Calculation Chart Error Detected Error **
Detected Error 2
x 3
x x
x 4
x x
~
5 x
x 6
x 7
x x
8 x
9
-x x
x 10 x
x x
11 x
x x
12 x
x x
13 x
x x
14 x
x x
15 x
x x
16 x
x
- Misadministration #1 is discussed in Section 3.3.
- Several licensees indicated that either independent verification of dose calculations or improved chart reviews could have detected the error before a misadministration occurred.
In cases where licensees did not indicate that independent verification or chart reviews could have detected the error, AE00 assigned one or both of these activities if the misadministration was similar to one in which the licensee assigned the comparable activity as being able to detect the error.
o-
'. l l
the misadmini~trationc If.the errors had been detected early in the treatment, s
the treatment could have been terminated and/or the dosage adjusted to compensate for the error.
All of the errors involved either the treatment planning / dose calculation phase or the treatment phase of the therapy.
Errors leading to 12 of the 15 misadministrations could have been detected by an independent verification of the patient dose calculations or by timely and improved review of patient charts during the therapy process.
Of the 12 errors that could have been detected by independen',' verification of dose calculation or by timely and improved chart reviews, independent verification of dose calculations could have detected 8; timely chart reviews could have detected all 12 errors.
Independent verification of patient dose calculations should detect those
. errors where a misinterpretation of the physician's orders or an error in dose calculations led to a misadministration, because an independent workup of dose calculations starting with the physician's order should not reproduce the same errors.
In two cases where licensee personnel indicated that dose calculations
.had been checked by a second individual, it appears that those checks consisted only of checking the accuracy of the arithmetic in the calculations.
Conse-quently, errors that were made in misinterpreting a physician's. order were not detected.
Independent verification of dose calculations should encompass verification of the interpretation of physician's orders, the value of constants used in the calculations, etc.
Patient chart reviews should detect errors in those cases where the treatment times were too long (i.e., treatments greater than prescribed) because the accumulated dose as well as the dose fraction is normally recorded on the patient chart, and the total prescribed dose could have been compared with the product-of dose / treatment fraction an'd the number of prescribed fractions.
Overtreatment should have been evident when the accumulated dose became greater than or equal to the prescribed dose with some treatments remaining to be given.
In several misadministrations, there were indicators that could have alerted licensees to the fact that patients probably were being overtreated, licensee personnel did not appear to be perceptive of the indicators. For example:
In two teletherapy cases (12 and 15) the patients developed either an erythema which increased in severity with treatment
!~
or an unduly severe scalp reaction.
These symptoms did not lead licensee personnel to check the correctness of the dose j
calculations or treatment.
In five of the teletherapy cases, the treatment fractions were at least 50% greater than the prescribed treatment fractions (11, 12, 13, 14, 15, 16), which resulted in correspondingly higher machine timer settings.
In three of those cases, the timer settings differed by a factor of two or more from the setting for the prescribed dose.
In only one case (14) did the technologist question the timer setting as possibly being i
excessive.
The physicist to whom the question was directed apparently did not take action to adequately review the treatment plan.
4 I
t
~-.- ---._.
... 1 In their own reports of the therapeutic misadministrations to the NRC, licensees have identified independent verification of patient dose calcula-tions and/or improved chart reviews as the proper corrective action to prevent the recurrence of misadministrations involving errors in miscalculations, misinterpretation of physician's orders, or errors in identification.
Independent verification of radiopharmaceutical doses (e.g., iodine-131 therapy doses) is normally required by license condition.
This requirement is based on radiation safety considerations for the patient.
However, there is no equivalent regulatory requirement for independent verification of sealed source therapy dose calculations or for brachytherapy source activity.
3.3 Teletherapy Misadministration Involving Beam Parameter Measurements i
One misadministration involving teletherapy machines (1) resulted from an error made in the measurement of the tra.nsmission of cobalt-60 radiation through a wedge filter block.
The misadministrations that resulted from the wedge block correction factor error continued over a three year period, during which at least 53 of 900 patients treated using the incorrect we'dge correction factor received radiation doses that were below the prescribed doses by 10-15%.
Wedge filters are generally used to' configure the treatment field for only a portion of the i
treatment.
The fraction of the treatment varies from patient to patient and depends on the treatment plan.
Therefore, according to the licensee's. report, 3
the treatment doses that differed from the prescribed doses by 10-15% were within the range of doses generally accepted for the specific treatments.
The errors involved four wedge filters, which are wedge-shaped lead blocks placed in the path of the radiation beam to produce a defined gradient of radiation in the treatment field.
Radiation transmission factors determined by measurement in July 1980 were used until August 1983 when, during a complete calibration of the machine, the error was discovered.
A comparison of the wedge correction factors is presented in Table 3.
TABLE 3 Wedge Facter Comparisons for 1980 and 1983 Measurements Wedge Filter Wedge Factor 1980 Wedge Factor August 1983 20 1.16 1.34 30 1.20 1.44 45 1.44 2.08 L
60 1.62 2.70 The initial wedge factor measurements were done by a qualified individual. The l
error was made in the measurement of the transmission of cobalt-60 radiation through the filters.
Although the calculations that-produced the wedge correction factors were found to be correct, an erroneous measurement reading used in the calculation resulted in the error.
i-During the three year period that the wedge factors were used, the licensee l
performed the annual full calibration and periodic spot checks (at least l
monthly) of the cobalt-60 machine as required by 10 CFR 35.21 and 35.22.
l However, the licensee did not recheck the wedge factors during this period, l
nor were they required to do so by the regulations.
l l
l
22 -
The NRC regulations that require an annual full calibration of cobalt-60 teletherapy machines and periodic spot checks of the machines (10 CFR 35.21 and 35.22) evolved from a study sponsored by the Bureau of Radiological Health (now the Center for Devices and Radiological Health) and from the investigation of a group of misadministrations that occurred at Riverside Hospital, Columbus, Ohio, in 1976 (Ref. 5).
The cause of this group of misadministrations was the use of the wrong machine output in dose calculations.
The erroneous output resulted from an error in plotting the decay of cobalt-60.
The error produced a graph indicating that the source activity was lower than the actual value; thus, treatment times were longer than required, resulting in patients receiving radiation doses higher than prescribed.
The cause of the misadministrations that resulted from the wedge factor error is similar to that of the misadministrations that occurred at Riverside Hospital.
Both i_nvolved an error in the exposure rate or a factor related to
~
the exposure rate, and the use of an erroneous factor continued over a period of years.
An annual or more frequent check of the machine output or correction factors related to machine output would have uncovered the error and minimized the effect of the error on patient treatment. While the changes in NRC regulations (addition of section 10 CFR 35.21 and 10 CFR 35.22) that evolved, in part, from the Riverside Hospital misadministration events address the machine calibration problem, the new regulations,do not require that correction factors for beam modifying devices such as wedge filters be verified during the annual calibration of teletherapy machines.
3.4 Brachytherapy Misadministrations The two brachytherapy misadministrations were very similar to each other and concerned cases in which the wrong activity sealed sources were used (17, 18).
The wrong activity brachytherapy sources were loaded into shielded containers by a technologist being trained as a dosimetrist in one case, and by a dosi-metrist in the other case, and were delivered to the therapist for insertion into an "after-loading"* device positioned in the patient.
The sources were color-coded but were otherwise unlabeled.
The color-coding on the sources was either a colored dot or band on the body of the source. In both cases, different activity sources were stored in the same drawer of a storage cabinet.
In each of these two misadministrations, the technologist in the first case and the dosimetrist in the second, were familiar with the color codes used for loading sources, and had performed the task successfully on previous occasions.
The technologist had removed or replaced sources about four times a month for about 10 months.
The dosimetrist had been performing this procedure for eight years.
In neither case did the therapist independently verify that the correct sources were loaded in the applicator before, or concurrent with, implanting the sources in the patient, nor were there any NRC or licensee requirements that the therapist verify the source activity.
An independent verification of the source strength should have detected the error.
- This is a type of source applicator that is first placed in the tumor treatment location in the patient and then loaded with the required brachytherapy sources.
Personnel conducting the required room radiation surveys (Ref. 4), which each licensee indicated were performed following the implantation of the sources, failed to detect that higher activity sources had been implanted than had been prescribed.
In one case, the implanted source activity was about two-and-one-half times higher than the prescribed activity, and in the other case the implanted source activity was about 15% higher.
Room / patient radiation survey levels should, therefore, have been comparably higher.
The misadministration event involving two-and-one-half times the prescribed source activity should have been readily detected from room / patient survey results.
These two brachytherapy misadministrations involved the use of the wrong brachytherapy sources by experienced personnel.
The misadministrations that resulted from the use of the wrong sources could have likely been prevented if a second individual was required to independently verify that the correct sources were loaded before, or concurrent with, the sources being implanted in the patient.
In their reports of the brachytherapy misadministrations to the NRC the involved licensees identified, as the proper corrective action, that personnel independently verify that the correct sources have been loaded in the source applicator as a way to prevent this type of misadministration.
3.5 Present NRC and Industry Efforts Relating to Patient Radiation Safety in Radiotherapy 3.5.1
, Regulatory Requirements NRC published a policy statement (Ref. 7) on the regulation of the. medical uses of radioisotopes to serve as further guidance in interpretation of the regulations.
The three salient points of the policy are:
The NRC will continue to regulate the medical uses of radoisotopes as necessary to provide for the radiation safety of workers and the general public.
The NRC will regulate the radiation safety of patients where justified by the risk to patients and where voluntary standards, or compliance with these standards, are inadequate.
The NRC will minimize intrusion into medical judgments affecting l
patients and into other areas traditionally considered to be a part l
of the practice of medicine.
With respect to the second point, three examples of existing NRC requirements that relate to the radiation safety of patients are:
Physicians who use, or directly supervise the use of, radioisotopes l
must submit a record of their training and experience to NRC i
($35.11(d)).
j Licensees authorized to use teletherapy machines for treating humans must have the machine calibrated by a qualified expert.
The j
qualifications are specified in S35.24.
' Regulatory Guide 10.8, Guide for the Preparation of Applications for Medical Programs, states that "All radiopharmaceuticals should be assayed for activity to an accuracy of +10% of the true value prior to being administered to patients."
Licensees are committed to this practice in the license.
The existing regulations do not address patient radiation safety as it relates to ensuring the accuracy of dose calculations and/or delivery of treatment doses.*
3.5.2 Industry Requirements Independent verification of dose calculations, source activity (brachytherapy sources), measurements relating to patient dose calculations, and the adequacy of patient chart reviews are normally addressed in quality assurance programs ** for radiotherapy facilities.
Medical professional societies associated with radiation therapy, such as the American Association of Physicists in Medicine (AAPM), the American College of Radiology (ACR), and the American Society for Therapeutic Radiology and Oncology (ASTRO), are strong advocates of quality assurance programs in radiation therapy treatment to insure proper patient care.
Governmental agencies, such as the National Cancer Institute and the Center for Devices and Radiological Health, are also actively involved in efforts to promote and improve quality assurance procedures in radiation therapy treatment.
A paper presented by Robert J. Shalek, Ph.D.,' entitled " Criteria for Quality Assurance Programs in Radiation Therapy and Legal Duty" (Ref. 7) includes a discussion of the types of errors that can lead to misadministrations and how there trrors can be detected before hand.
An excerpt from that paper states:
Attitudes and Procedures for Avoiding Large Errors It is the large error, such as arithmetic miscalculations, the use of data for the wrong treatment machine, the misinterpretation of written instructions, the incorrect decay of a radioactive source, the use of inappropriate factors for calculation, the overlap of treatment fields, and the misfunction of a treatment machine, that result in doses to the patient of 15% to 400% different from those intended.
- A proposed amendment to 10 CFR 35 to codify this requirement was published for comment on September 1, 1982.
This proposed amendment has been incorporated in the proposed revisions to 10 CFR Part 35 that NRC published for comment in the Federal Register on July 26, 1985 (50 FR 30616).
- Comprehensive quality assurance programs in radiotherapy include both the clinical and physical aspects of radiation treatment.
o Three suggestions made by the author for avoiding large errors are:
1.
Reged redundancy as a virtue and not a mark of inefficiency.
Important measurements and calculations relating to individual patients should be checked by a person who did not do the~ calculation.
Independent review of systems of measurement and calculation by outside persons often reveals errors repeat'ed over and over.
- 2.. Regard computer calculations with suspicion.
It is good practice to check every computerized treatment plan by some simple manual check, perhaps to a single, easily calculated point.
The stylized output of computers sometimes confers credibility that is undeserved.
3.
Check accumulating dose to patients at least weekly. Literally hundreds of errors and.inccnsistencies have been discovered by visiting physicists of the RPC [ Radiological Physics Center] in patient chart review.
If physicists take responsibility for the correctness of dose delivered to the patient, then this weekly check by a physicist is indispensable.
The author states that "All of the above advice was derived from factual situations in law suits or from review visits."
In October 1984, AAPM also published " Physical Aspects of Quality Assurance in Radiation Therapy" (Ref. 9) which addresses comprehensive physical quality assurance programs in radiotherapy facilities (e.g., dosimetry treatment planning, treatment machines and simulators, and radiation safety).
The American College of' Radiology (ACR), under contract with the Division of Training and Medical Applications of the Bureau of Radiological Health (now the Center for Devices and Radiological Health) in cooperation with the Division of Resources Centers and Community Activities of the National Cancer Institute, developed a quality assurance manual, Quality Assurance in Radiation Therapy:
A Manual for Technologists which was published by ACR in 1982 (Ref. 10).
This manual covers physical quality assurance program recommendations for teletherapy and brachytherapy treatment facilities.
Chapter 1 lists several patient chart defects that may lead to treatment error, i
for example:
i I
1.
Doctor's prescription i
a.
Omission of any treatment parameter b.
Illegible handwriting c.
Failure to write orders changing prescription 2.
Dosimetrist or technologist a.
Miscalculation of time b.
Miscalculation of daily maximum or tumor dose c.
Failure to record exact patient.p'osition d.
Incorrect measurements of patient thickness, etc.
i e.
Failure to make changes in calculations based on changes in. treatment parameters or machine output i
I
3.
Treating technologist a.
Errors in addition b.
Errors in timer or monitor unit settings c.
Errors in patient position parameters d.
Failure to note changes in treatment parameters e.
Failure to note changes in prescription f.
Failure to use prescribed treatment devices While medical professional groups and governinent agencies other than the NRC are involved in encouraging quality assurance programs in radiotherapy facilities, adherence by radiotherapy facilities to recommendations made by these groups is voluntary.
There are no generally accepted industry standards that address the verification of patient dose calculations, or the quality of patient chart reviews.
Consequently, many facilities may not have program activities that are consistent with these recommendations for cor.prehensive quality assurance programs.
Despite these above mentioned programs, the NRC did receive reports on l
27 therapy misadministrations during a 3 1/2 year period.
4.0 FINDINGS l
(1) Of the 16 teletherapy misadministrations reviewed in this study, 12 could have been prevented by improved patient chart reviews or in most cases by independent verification of patient dose calculations.
In addition, one of the 16 misadministrations could have been prevented by independent verification of measurements made in calculating wedge filter correction factors, and one misadministration could have been prevented by independent verification of the tumor depth measurements.
Such actions were identified by licensees as the appropriate corrective action for the misadministration events that have occurred.
l (2) The two brachytherapy misadministrations could have been prevented by licensee personnel independently verifying that correct brachytherapy sources were loaded into the source applicator before, or concurrent with, implanting the brachytherapy sources.
Such independent verifi-i cation was the appropriate corr'ective action identified by the licensees l
in the case of the two misadministrations.
(3) The teletherapy misadministration that involved 53 patients over three years involved human error in measuring the transmission of cobalt-60 1
rediation through a wedge filter.
The regulations issued in November 1980 that require teletherapy machine calibration (10 CFR 35.21) do not require that corrections factors for beam modifiers such as wedge filters l
be verified during the annual calibration of teletherapy machines.
(4) Adverse patient reactions were factors in prompting licensee personnel to review treatment plans in only three of the misadministration cases l.
despite the fact that'in at least six cases treatment fractions exceeded the prescribed fraction by over 50L Licensee personnel did not appear
{
perceptive in associating adverse patient reactions (which occurred in at least two misadministration cases) or in noting excessive timer i
l setting as possible indicators of misadministrations.
I
., (5) Although professional medical groups involved with radiotherapy and rela.ted government agencies encourage quality assurance programs in radiotherapy facilities, no government agency or nongovernmertal accrediting body requires that radiotherapy facilities have quality assurance prcgrams that conform to the programs recommended by professionai medical groups.
Thus, many facilities may not have quality arsurance programs that are consistent with recommendations of medicai professional groups involved with radiation therapy.
(6) Our analysis indicates that Agreement State licensees are likely to experience the same frequency and types of errors found for NRC licensees.
As a result, the recommendations for corrective actions contained,in this report are applicable.to Agreement State licensees as well as NRC licensees.
5.0 RECOMMENDATIONS (1) AEOD recommends that the Office of Nuclear Material Safety and Safeguards (NMSS) should communicate the information contained in this report to the affected licensees.
(2) AE0D recommends that the Office of Nuclear Material' Safety and Safeguards (NMSS) should consider'the following actions in regard to establishing quality assurance requirements for radiotherapy facilities
- licensed by NRC.
Contact appropriate professional organizations to encourage and support the initiation of a voluntary, industry-directed physical quality assurance program for radiotherapy facilities.
We believe that the commitment of the professional organizations in this regard should be assessed by the NRC and a conclusion reached as to the effectiveness of the voluntary program within two years.
If substantial progress toward completion of the voluntary program, including a final completion date, hassnot been demonstrated at the end of two years, we recommend that NMSS initiate the necessary studies to
. determine whether a rulemaking is justified to require
~that radiotherapy facilities licensed by NRC have quality assurance programs to insure the accuracy of patient doses..The program should include such things as:
independent verification of patient dose calculations and independent verification of the activity of brachytherapy sources before the sources are implanted.
- A comprehensive quality assurance prog am in radiation therapy has both a clinical component and a physical component.
The clinical component includes such things as clinical evaluation of the patient, therapeutic decision (e.g., curative, or pallative treatment, and choice of treatment modalities).
The physical component includes such things as dosimetry, treatment planning, treatment machines and simulators, and radiation safety.
O e.
The voluntary quality assurance program should contain at least the elements outlined above.
(3) 10 CFR Part 35.21 should be amended to include the' calibration of beam modifiers such as wedge filters, shaping filters, trays, etc.
(4) In addition, to.the extent that the NRC implements recommendation 3, the action should be made an item of compatibility for Agreement States.
b e
6 e
p 0
b
6.0 REFERENCES
(1) Kramer, S., Hanks, G.E., and Diamond, J.J., " Summary Results from Fourth Facilities Master List Survey Conducted by Patterns of Case Study," Int.
J. Radiat. Oncol. Biol. Phys. 9.12, 1983.
.(2) NRC, AE00 Report AE00/N204A, " Report on Medical Misadministrations for 1981," March 1982.
(3) Criteria for Radiation Oncology in Multidisplinary Cancer Management, Report to the Director of the National Cancer Institute, National Institutes of Health, by the Committee for Radiation Oncology Studies, Grant, CA 25791, February 1981.
(4) NRC, Regulatory Guide 10.8 " Guide for the' Preparation of Applications for Medical Programs" October 1980, pp. 47-49.
(5) Vacca, Patricia C., NRC, Presentation at the Plenary Session of the American Association of Physicists in Medicine, August 3, 1977.
(6) 42 FR 25746,' " Regulation of the Medical Uses of Radioisotopes, Statement of General Policy," February 9,1979.
(7) Shalek, Robert J.,
Ph.D., " Criteria for Quality Assurance Programs in Radiation Therapy and Legal Duty," Proceedings of a Symposium on Quality Assurance in Radiotherapy Equipment, Missouri River Valley Chapter, AAPM, June 1982, pp. 14-15.
(8) Svensson, G.K., Baily, N.A., Loevinger R., Morton, R., and Wright, K.A.,
Physical Aspects of Quality Assurance in Radiation Therapy, Report #13, May 1984.
(9) Wizenberg, Morris, J., M.D., ed., Quality Assurance in Radiation Therapy.
A Manual for Technologists, published by the American College of Radiology under contract with the Division of Training and Medical Applications of the Bureau of Radiological Health (BRH).
l
. APPENDIX A Descriptions of 16 Teletherapy and two Brachytherapy Misadministrations, Reported to the NRC (November 1980-July 1984)
I.
Therapy Misadministrations Involving the Use of Teletherapy Machines MISAD #:
1 Type:
Dose differing from prescribed dose by >10%
Cause:
Apparent-human error in the measurement of the transmission of Co-60 radiation through a wedge filter.
Contributing Factors:
(1) No independent verification of wedge filter transmission measurements; (2) Failure of licensee to recheck previous measurement in a timely manner.
When Was Error Detected:
Three years after erroneous parameter fir'st used.
How Error Was Detected:
During complete calibration of Co-60 teletherapy system in preparation for use of new treatment planning computer, all beam modifier measurements were checked.
Indications of Misadministrations:
None Principal Licensee Personnel Involved:
Physicist Licensee's Proposed Corrective Actions:
Require independent verification of parameter measurements.
==
Description:==
An error was made in measuring wedge filter transmission factors.
The filters are wedge-shaped lead blocks placed in the path of the radiation beam to produce a defined gradient of radiation in the treatment field.
The under-treatment of at least 53 of approximately 900 patients treated by tele-therapy irradiation from July 1980 to August 30, 1983 resulted from the error.
Most of the 53 cases were 10-15% below the prescribed dose; however, four cases were.30% below the prescribed dose.
In 38 cases the licensee still had contact with the patient and had noted three cases where cancers (neoplasms) had recurred.
The error was discovered during an annual output calibration measurement that included a check of all wedges used in the treatment of patients.
A dis-crepancy was found between the July 7, 1980 calculated wedge filter trans-mission factors and the August 30, 1983 calculated factors.
For example, the 60 degree angle wedge, which had a factor of 1.63 based on data and calcu-lations from 1980 had been recalculated based on August 30, 1983 data to have a facter of 2.70. Therefore, the licensee's patients treated with this wedge received radiation doses less than those prescribed by the physician.
' 1.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
MISAD #:
2 Type:
Dose differing from prescribed dose by >10%
Cause:
Human error in setting up patient for treatment.
Contributing Factors:
No independent verification of treatment set-up.
When Was Error Detected:
After one treatment.
How Error Was Detected:
Review of treatment plan.
Indicators of Misadministrations:
None t
PrincipalLicenseePersonnelInvolved$
Therapist Licensee's Proposed Corrective Actions:
Install treatment simulator.
==
Description:==
A patient was set up for cobalt-60 radiation therapy treatment to the right breast, when the left breast was the one with the carcinoma.
The patient received one treatment of 200 rads.
There was na apparent injury.
The therapist was directly involved with the setup and notified the patient and the referring physician.
4 i
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0
. 1.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
'MISAD #:
3 Type:
Dose differing from prescribed dose by >10%
Cause:
Multiplication error in calculating the time that Co-60 source was exposed.
Contributing Factors:
(1) No independent verification; (2) Failure of licensee to recheck calculations and ongoing therapy in a timely manner.
When Was Error Detected:
Two months after treatment ended.
.How Error Was Detected:
Patient chart review.
Indicators of Misadministrations:
None Principal Licensee Personnel Involved:
Dosimetrist Licensee's Proposed Corrective Actions:
Require that all treatment times are checked by a second individual.
==
Description:==
A patient scheduled for cobalf lit <tre apy treatment of 3000 rads was administered a dose of 3345 rads (11.5% et.ertfa ec ment).
The treatment period was from December 22 to January 6 of the next year (10 treatments). The error was discovered on March 10.
The overtreatment occurred due to an error in calculating the time that the cobalt source was exposed.
.; 1.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
MISAD #:
4 Type:
Dose differing from prescribed dose by >10%
Cause:
The technologist misread the scheduled treatment time as 1.89 minutes instead of the correct time of 1.39 minutes.
Contributing Factors:
Licensee failed to perform adequate chart reviews.
When Was Error Detected:
After 11 of 12 scheduled treatments.
How Error Was Detected:
Patient chart review.
Indicators of Misadministrations:
None' Principal Licensee Personnel Involved:
Technologist, Physicist, Dosimetrist
==
Description:==
A treatment of 3000 rads to the midline of the brain in 12 equal fractions of 250 rads each via two lateral beams was prescribed.
The treatment time for each beam was calculated to be 1.39 minutes.
The dosimetrist calculated the treatment time on the physics calculation sheet and then entered it in pencil in the first treatment column on the daily treatment record sheet.
The calculations were then checked by a physicist who initialed both the physics calculation sheet and the chart check column in the daily treatment record sheet.
In the hospital's procedures, when a patient is treated for the first time, the treatment time and the doses which have been written in with pencil by the dosimetrist are overwritten in ink by the technologist who administers the treatment.
In this case, the first treatment was administered for 1.89 minutes instead of 1.39 minutes.
This mistake was then carried on for 10 more treatments. The mistake was discovered after the lith treatment.
The 12th treatment was cancelled.
The patient received 3753 rads instead of the prescribed 3000 rads.
\\
0
~.
1.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
MISAD #:
5 Tygei Dose differing from prescribed dose by >10%
Cause:
Arithmetic. error in the addition of therapy segments.
Contributing Factors:
Failure to independently verify calculations or conduct timely chart revi.ew of therapy progress.
. When Was Error Detected:
After completion of therapy treatment.
How Error Was Detected:
Patient's chart review.
Principal Licensee Personnel Involved:
Technologist, Physicist, Dosimetrist Licensee's Proposed Corrective Actions:
Organize new chart review committee; change record format to improve system of cross checks.
==
Description:==
A patient with widespread metastatic carcinoma of the breast was referred to_ therapy with a chief complaint of massive swelling of the left arm due to... ttensive disease in the left axilla.
Treatment of the left axilla with q
cobalt teletherapy began on March 2.
Treatment ended on April 20 after delivery of a total of 6173 rads.
The misadministration involves the treatment exposure record.
Initially, the prescribed treatment was reviewed daily, but early response led to a prescribed three-week treatment regime with a total dose of 4575. The response at the end of the three week period was so favorable that additional treatment was prescribed by the radiotherapist.
Treatment was stopped by the radiotherapist after a recorded tumor dose of 5373 with the patient doing well.
It was later determined that there had been an arithmetical error _made in the addition of 1
the therapy sements and that the actual tumor dose delivered was 6173 rads to the axilla.
This error was found by the physics division during the routine check of the record as the record was being retired following discharge of the 3
patient.
i 1
j I.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
MISAD #:
6 Type:
Dose differing from prescribed dose by >10%
Cause:
Error in determining the tumor depth.
Tumor depth stated to be 16.5 cm on patient chart was found to be 11.5 cm.
Contributing Factors:
(1) Failure to verify tumor depth before initiation of patient treatment; (2) failure to do complete quality control check of all factors that determine patient dose during treatment period.
When Was Error Detected:
During follow-up visit after treatment.
. How Error Was Detected:
Remeasurement of. tumor dose by oncologist.
Indicaters of Misadministrations:
None Principal Licensee Personnel Involved:
Therapist Licensee's Proposed Corrective Actions:
Exercise greater care in determination of tumor depth.
Descripti~on:
A patient undergoing radiation therapy was administered a tumor dose of 5570 rads instead of the prescribed tumor dose of 4070 rads.
The error occurred because of an error in measuring the tumor depth.
Before treatment was begun, the tumor depth was measured to the 16.5 cm and dose calculations were based on this measurement.
During the last of several subsequent patient followup visits after completion of therapy, the radiation oncologist remeasured the patient and found that the tumor depth should have been stated as 11.5 cm.
~
. I.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
MISAD #:
7 Type:
Dose differing from prescribed dose by >10%
Cause:
Treatment calculation depth was incorrectly entered on patient log.
Contributing Factors:
(1) No independent verification of treatment parameters; (2) Failure to perform timely or adequate checking of patient treatment chart.
When Was Error Detected:
After completion of first treatment phase.
How Error Was Detected:
While calculations were being done for a second treatment phase.
Indicators of Misadministrations:
None Principal Licensee Personnel Involved:
Physicist, Dosimetrist Licensee's Proposed Corrective Actions:
None
==
Description:==
A patient, prescribed a dose of 4500 rads, was administered a dose in excess of 6000 rads.
The misadministration occurred because the treatment depth to be used in the dose calculation was incorrectly entered on the patient's chart.
This was discovered as calculations were being prepared for a second treatment for the patient.
a.
37 -
I.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
MISAD #:
8 Type:
Dose differing from prescribed dose by >10%
Cause:
Therapist failed to annotate radiotherapy treatment sheet to reflect a change in the therapy prescription requiring a reduction in the tumor treatment area.
Contributing Factors:
None When Was Error Detected:
At completion of treatment.
How Error Was Dete'cted:
Patient chart review.
Indicators of Misadministrations:
None Principal Licensee Personnel Involved:
Therapist Licensee's Proposed Corrective Actions:
Record all intended therapy procedures on therapy prescription form.
==
Description:==
A teletherapy misadministration resulted in administering about 2475 rads to a portion of a lung.rather than the originally prescribed 1500-1800 rads.
The original prescription called for administering 3000 rads to all sites of the initial disease in the lung.
Because the therapist felt that the volume of lung involved could not tolerate the dose, he elected to reduce the area of lung to be irradiated after 1500-1800 rads had been administered.
A filter block to reduce the area being irradiated was not inserted as intended by the therapist, because the prescription had not been updated by the therapist before this phase of the treatment.
The patient may have increased risk of pneumonitis.
'I.
Therapy Misadministrations Involving the Use of Teletherapy Machines Continued)
MISAD #:
9 Tyge:
Dose differing from prescribed dose by >10%
Cause:
Erroneous data' generated by one computer program was used in another computer treatment plan resulting in overtreatment for the last 3 of 5 treatments.
Contributing Factors:
(1) Poor quality control in the use of a computer treatment-plan; (2) failure to verify the results of computer generated treatment data.
When Was Error. Detected:
After completion of treatment.
5 How Error Was Detected:
Patient chart review.
Indicators of Misadministrations:
None Principal Licensee Personnel Involved:
Therapist, Dosimetrist Licensee's Proposed Corrective Actions:
(1) Remove erroneous data from the computer; (2) verify future treatment plans generated by computer by a single central axis hand calculation., (3) compare all external beam isodose curves with measured data before using.
==
Description:==
A patient undergoing teletherapy treatment to the right posterior chest was administered a radiation therapy dose of 3200 rads instead of the prescribed dose of 2000 rads.
The treatment was administered in two treatments of 400 rads and three treatments of 800 rads.
The misadministration apparently occurred because of a combination of erroneous data from the treatment planning system computers and a miscalculation based on those data.
The error was discovered when the calculations were rechecked after completion of the treatments.
_m.
- . I.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
MISAD #:
10 Type:
Dose differing from prescribed dose by >10%
'Cause:
Hand calculated treatment parameters were employed for two treatments after which time a computer analysis was worked up.
In this analysis an error was made in converting rads / day to machine on-time.
Contributing Factors:
(1) No independent verification of patient dose calculations; (2) failure to perform timely or adequate check of patient treatment chart.
When Was Error Detected:
After completion of treatment.
How Error Was Detected:
Patient chart review.
Indicators of Misadministrations:
None Principal Licensee Personnel Involved:
Therapist, Dosimetrist Licensee's Proposed Corrective Actions:
I'nsure that multiple dosimetry crosschecks.are performed in a timely manner.
==
Description:==
A patient scheduled for a 3000 rad cobalt-60 teletherapy treatment was administered a dose of 3614 rads.
The patient treatment prescribed by the radiotherapist was 3000 rads minimum tumor dose to the patient's whole brain to be delivered in 10 fractions utilizing two lateral, pair-opposed cobalt-60 teletherapy radiation fields.
The misadministration was detected during the final dosimetry check by the physics department personnel who determined that the total dose delivered to the tumor was 3614 rads.
On July 31 a hand calculation was performed correctly for the treatment of the patient who was to receive a total of 300 rads per day from two lateral fields.
The hand-calculated treatment parameters were employed for two treatments, at which time a computer analysis was worked up for determining a more precise schedule for the remainder of the treatment.
An error in converting from rads / day to minutes of exposure per day occurred at this point in the planning process on August 4.
This incorrect time was used through the remaining eight days of treatment.
. I.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
MISAD #:
11 Type:
Dose differing from prescribed dose by >10%
Cause:
The dosimetrist used a dose rate factor from a. table for a different machine.
Contributing Factors:
(1) No independent verification of patient dose calculations for patient treatment plan; (2) dose rate factors for several machines were kept in the same book.
When Was Error Detected:
After 27 treatments.
How Error Was Detected:
Dosimetrist detected error while revising patient treatment plan.
Indicators of Misadministrations:
None Principal Licensee Personnel Involved:
Therapist, 00simetrist
' Licensee's Proposed Corrective Actions:
(1) Separate data for each machine
'into separate binders;~(2) enter dose rate factor used in dosimetry calcu -
lation in patient's treatment plan.
==
Description:==
A patient undergoing cobalt-60 teletherapy treatment was administered a dose of 8100 rads instead of the 6500 rads dose intended.
The error in treatment was detected during a revision of the patient's treatment time for another procedure by a radiation dosimetrist.
At the time the error was detected, the patient's treatment record indicated that a cumulative dose of 4860 rads at 180 rads / fraction in 27 fractions had been delivered, whereas the patient had actually received 8100 rads at 300 rads / fraction in 27 fractions. The treatment plan for this patient was devised at one hospital and transferred to a second hospital where the dose was administered.
Calculation of the treatment time requires the dosimetrist or physicist to obtain the calibrated dose rate for the particular treatment machine from a table of dose rate vs. field size.
Tables for three machines are kept in the dosimetry work area in a single binder separated by dividers.
The error occurred because the dosimetrist obtained the dose rate from the table for a machine different from the one to be used and the physicist reviewing the treatment plan did not detect the error, b
. I.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
MISAD #:
12 hpe:
Dose differing from prescribed dose by >10%
Cause:
Dosimetrist made an error in calculating the time the machine was on using 200 as the number of rads per treatment field for each treatment fraction.
This was later reduced to 150 rads per treatment field.
Contributing Factors:
(1) No independent verification of patient dose calculations; (2) inadequate patient chart checks.
When Was Error Detected:
After 24 treatments,15 at 400 rads / fraction and 9 at 300 rads / fraction.
How Error Was Detected:
Skin reaction of patient prompted' a check of treatment time calculations.
Indicators of Misadministrations:
Patient developed erythema which increased,
in severity with the treatment.
Principal Licensee Personnel Involved:
Therapist, Oosimetrist Licensee's Proposed Corrective Actions:
Have a physicist double check the dosimetry calculations before the patient's third treatment.
==
Description:==
A patient undergoing teletherapy treatment of the brain received a dose of 8700 rads instead of the prescribed dose of 6000 rads. The treatment prescribed for the patient was 200 rads total dose per day to the midline of the brain via two lateral radiation beams.
Thus, each lateral field should have contributed 100 rads per day total dose delivered to the midline of the brain.
The patient received 15 treatments at an actual rate of 400 rads / day (200 rads / day per field) for a cumulative dose of 6000 rads. The patient developed erythema (severe reddening of the skin) during the treatment course.
Because this condition was more severe than anticipated, the attending physician reduced the prescribed dose to 150 rads per treatment after the 15th treatment.
A second dosimetrist calculated a new exposure time, repeating the original error.
The dosimetrist who calculated the original treatment dose erred in calculating the exposure time so that 200 rads was administered to each side of the head (twice the intended amount of radiation per treatment).
The severity of the erythema continued to increase and after nine treatments at the reduced level the physician asked for a review of the dose calculations.
The recheck identified the error and the treatment was stopped.
The patient had received a total of 8700 rads which was 45% more than the prescribed dose.
I.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
MISA0 #:
13 lype:
Dose differing from prescribed dose by >10%
Cause:
Dosimetrist or physicist misinterpreted the physician's prescription and calculated machine on time for 200 rads per treatment field per treatment fraction instead of 100 rads per treatment field.
Contributina Factors: (1) No independent verification of patient dose calculations; (2) inadequate patient chart checks.
When Was Error Detected: After 16 treatments.
How Error Was Detected:
During routine patient chart review.
Indicators of Misadministrations:
None Principal Licensee Personnel Involved:
Therapist, Dosimetrist, Physicist Licensee's Proposed Corrective Actions:
(1) Restate to staff proper procedures for calculating and specifying. daily tumor dose for multifield treatment techniques; (2) reemphasize ~importance of chart review; (3) have more than one individual check dose prescription.
==
Description:==
A patient undergoing teletherapy radiation therapy treatment of the brain with a prescribed dose of 4000 rads received a 6400 rad dose to the treatment area.
The prescribed dose was to be administered from both the front and the side of the head (100 rads per side).
Hospital therapy personnel erroneously calculated the exposure time so that the patient received 200 rads from the front and 200 rads from the side.
The total exposure for each treatment was therefore twice that intended.
-The patient received 16 treatments at the elevated level for a total of 6400 rads compared to the intended total of 4000 rads.
The error was found during a review of the patient's treatment record by the therapist.
The licensee had quality control procedures to check the exposure calculations, but the checks apparently failed to detect the error in this case in a timely manner.
. 1.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
MISAD #:
14 Type:
Dose differing from prescribed dose by >10%
Cause:
Physician initially gave an oral prescription for 600 rads /
treatment times three treatments.
He later signed a written prescription calling'for 300 rads to be delivered in five
. treatments.
Confusion of the two prescriptions resulted in a treatment plan for 600 rads for five treatments.
The physicist who had checked the arithmetic accuracy of the dose calculations for the oral prescription transferred the data from these calculations to the patient treatment sheet.
Contributing Factors:
(1) Use of initial oral prescription for purpose of setting patient simulation by technologist; (2) Inadequate patient chart checks.
When Was Error Detected: After completion of therapy.
d How Error Was Detected:
Patient chart review following patient complaint of discomfort.
Indicators of Misadministrations:
One technologist questioned physicist about what appeared to be too long a treatment time.
Principal Licensee Personnel Involved:
Therapist, Physicist Licensee's Proposed Corrective Actions:
(1) Use written prescription to perform dose calculations; (2) before first treatment, require check of dose calculations by technologist and physicist; and make check of total number of parts, and tumor dose per part.
l l
]
i
)
l 2
. I.
Therapy Misadministrations Involving the Use of Teletherapy Machines (Continued)
MISAO #:
15 Tyge:
Dose differing from prescribed dose by >10%
Cause:
Error in dose calculation by technologist (checked by physicist without detecting the error) that resulted in 154 rads to each of two treatment fields instead of 100 rads to each field as prescribed.
Contributing Factors:
(1) Inadequate review of patient dose calculations by physicist; (2) inadequate chart check review of therapy progress.
When Was Error Detected:
After 22 treatments.
How Error Was Detected:
Chief technologist reviewed treatment plan because of patient reactions.
Indicators of Misadministrations:
Patient exhibited a severe scalp reaction.
Principal Licensee Personnel Involved:
Therapist, Physicist, Technologist Licensee's Proposed Corrective Actions:
Require physicist to generate own dosimetry calculations rather than check technologist's calculations.
==
Description:==
A patient scheduled for cobalt-60 teletherapy treatment (whole brain irradiation) was administered a. dose of 6776 rads instead of a prescribed dose of 6000 rads.
The original calculations called for a treatment time to each field (treatment utilizing opposed lateral fields of 1 minute 58 seconds to deliver 100 rads to the mid sagittal plane.
For this exposure time, the delivered dose was actually 154 rads to the mid-sagittal plane from each field, resulting in a daily misadministration error of approximately 50%.
The original dosimetry was done by a technologist on the cobalt unit.
The technologist initiated the calculation which was subsequently checked and initialed by the resident physicist.
The physicist reviewed the dosimetry and ongoing treatment record four times at two-week intervals (a standard of the licensee's procedure). Af ter 22 treatments and a projected dose of 4400 rads to the mid-sagittal plane, the patient exhibited severe scalp reaction.
Because of this, the dosimetry was rechecked by the physicist and no error was perceived.
The treatment was halted.
Three weeks later when the patient's scalp reaction had subsided, she returned to continue treatment, at which point the chief technologist reviewed the dosimetry and pointed out an error in the original dosimetry. Treatment had begun on April 22, the error was discovered on June 12.
. I.
Therapy Misadministrations Involving the Us'e of Te1etherapy
~
Machines (Continued)
MISAO #:
16 Type:
Dose differing from prescribed dose by >10%
Cause:
The 500 rads in three treatment segments of therapy was misread as 500 rads times three treatments.
Contributing Factors:
(1) No independent verification of dose calculations; (2) patient chart review not done before completing treatment.
When Was Error Detected: After completion of therapy.
How Error Was Detected:
Patient chart review.
Indicators of Misadministrations:
None Principal Licensee Personnel Involved:, Therapist, Physicist Licensee's Proposed Corrective Actions:
Require individual performing dose calculation to flag the patient treatment chart by folding the dosimetry sheet so that it sticks out of chart to alert physicist, technologist, and oncologist to review chart.
==
Description:==
A teletherapy misadministration to the mediastinal area of a young male Hodgkin's disease patient resulted in an overexposure of about 11%.
The prescribed dose was 4000 rads in 27 treatments plus 500 rads in three treatments.
The latter was misread as 500 rads times three treatments, so that the patient receivei 5500 rads.
The radiotherapist does not foresee any adverse affects to the patient because the spinal cord did not receive more than 4500 rads.
, _. _. _ - _ _ ~, _.,
. ~. _ _ _. _ -.
. II.
Therapy Misadministrations Involving'the Use of Brachytherapy -
Sources MISAD #:
17 Type:
Dose differing from prescribed dose by >10%
Cause:
The wrong activity sources were loaded in the brachytherapy source applicator.
The misloading involved loading a 17.4 mg radium equivalent source (color coded orange dot) instead of a 11.8 mg radium equivalent source (color coded white dot).
Contributing Factors:
(1) No independent verification of source activity by the therapist; (2) the sources not labeled as to activity although they were color coded; (3) both activity sources were stored in the same drawer.
When Was Error Detected:
One day after end of treatment period (30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />).
How Error Was Detected:
Physicist.while returning the sources to the storage safe.
Indicators of Mi'sadministrations:
The results of the patient's room radiation survey following the source loading should have indicated activity sources were used.
Principal Licensee Personnel Involved:
Dosimetrist (who' loaded sources from safe) and therapist.
Licensee's Proposed Corrective Actions:
(1) Advise dosimetrist of the requirement to inventory the sources at the time of removal and placement of sources; (2) require that all Physics Department staff handling the sources take inventory of sources in the safe before and af ter removing or replacing sources.
==
Description:==
A patient undergoing both internal and external radiation treatment for cervical cancer using teletherapy and brachytherapy methods was administered doses of radiation (to two treatment areas) from brachy-therapy sources that were 21% and 37% higher than planned or prescribed.
The total treatment dose from external and internal irradiation was 3.5% and 13% higher to the affected areas than prescribed.
The overtreatment resulted from the brachytherapy loading device (applicator) being loaded with 17.4 mg radium equivalent sources instead of 11.8 mg radium equivalent.
, - +
I.
Therapy Misadministrations Involving the Use of Brachytherapy Sources (Continued)-
MISAD #:
18 Type:
Dose differing from prescribed dose by >10%
Cause:
The wrong activity sources were loaded in the brachytherapy source applicator.
The misloading involved loading three 20.3 mg radium-e'uivalent sources (color coded white) instead of three 6.3 mg q
radium equivalent sources (color coded purple)
Contributing Factors:
(1) No independent verification of source activity by the therapist; (2) the sources were not labeled as to activity although they were color coded; (3) possible high work load.
When Was Error Detected:
End of treatment period.
How Error Was Detected: While returning the sources to the. storage safe physician noted a dif ference between color code of sources and prescription.
Indicators of Misadministrations:
The results of patient's room radiation sources loading should have indicated that the wrong activity sources were used.
Principal Licensee Personnel Involved:
Therapy Technologist who loaded sources from storage safe and Therapist.
Licensee's Proposed Corrective Actions:
(1) Revise written protocol for handling brachytherapy sources; (2) change brachytherapy source record form to emphasize the verification of the correct source loading by physician prior to application.
==
Description:==
A patient undergoing cesium-137 brachytherapy treatment was administered a dose of 12,000 rads to the uterus during a treatment period from April 9 to April 12.
The prescribed total dose was 4000 rads.
The error was caused when the wrong activity sources were loaded in a vaginal applicator.
The prescribed loading of sources for the brachytherapy application was one 9.9 mg radium equivalent source and three 6.3 mg radium-equivalent sources.
Three 20.3 mg radium equivalent sources were loaded instead of the prescribed three 6.3 mg radium equivalent sources.
The source loading was performed by a registered therapy technologist who was being trained as a dosimetrist.
The error was discovered by the physicist as the sources were being replaced in the storage safe upon removal from the patient.
The physicist noted that the source color coding did not match the color coding for the sources in the prescription (20.3 mg radium equivalent sources are color coded white., 6.3 mg radium-equivalent sources are color coded purple).
An examination of the patient three days after removal of the sources revealed no unexpected abnormalities in the vagina.
~
APPENDIX B Descriptions of Radiopharmaceutical Misadministrations and Brachytherapy i
Misadministrations Reported to the NRC but Not Included in the AE00 Case Study General-There were three brachytherapy misadministrations and six radiopharmaceutical misadministrations reported to NRC that were not included in section 3.0 of the case study report, because these misadministrations were found to have resulted from miscellaneous errors or specific procedural or equipment problems.
As a result, recommendations involving NRC rulemaking were not considered warranted.
Brachytherapy In the first brachytherapy case (19) a patient was being treated for cancer of the cervix using an intracavitary cesium implant.
A Fletcher Suit Tandem and Ovoids (four sources in the Tandem and one source in each Ovoid) was used. One of the sources slipped out of the Tandem part of the applicator some time during the treatment period and fell underneath the patient.
The second case (20) involved treatment of the vaginal cuff using two sources in a Delclos applicator.
The normally circular hole in the dome part of the applicator had become somewhat elliptical.
This made the source carrier difficult to insert and resulted in the sources not being placed in a location that would deliver the prescribed dose to the treatment area. Although the radiation therapist experienced difficulty in inserting the sources, the change in shape of the hole in the applicator was not discovered until after the applicator was removed from the patient and the sources were removed from the applicator.
The third case (21) involved a patient undergoing treatment with iridium-192.
There was a delay in evaluating the iridium implant volume using a computerized reconstruction of the iridium implant.
This delay led to an underestimate of the dose rate to the treatment area and resulted in an overtreatment.
Radiopharmaceutical Therapy Radiopharmaceutical therapy involves the use of radioisotopes such as iodine-131 as sodium iodide and phosphorus-32 as sodium phosphate or chromic phosphate for therapy procedures.
The isotopes are administered orally (iodine-131) or injected intravenously (sodium phosphate) or injected into a body cavity (chromic phosphate).
Radiopharmaceutical therapy as used in NRC regulations includes the treatment of hyperthyroidism as well as thyroid cancer (fodine-131).
While the overall therapy plan may include the general steps outlined in Figure 1, the specific substeps for radiopharmaceutical therapy would be much simpler.
Although treatment procedures can involve a series of treatments (for example, the treatment of thyroid cancer may involve one or more doses of iodine-131),
radiopharmaceutical therapy generally involves single treatment doses.
One notable difference between teletherapy or brachytherapy procedures and
radiopharmaceutical therapy is that in the former the radiation dose to the tumor is determined by the position of sources as well as source activity, whereas with radiopharmaceutical therapy the chemical form or specific element of the radiopharmaceutical determines which organ of the body receives the maximum radiation dose.
Because of this, the administration of the wrong chemical form of an isotope (e.g., sodium phosphate vs chromic phosphate) constitutes a misadministration.
The NRC regulates the use of radiopharmaceuticals for therapy unnr 10 CFR 35.100.
Regulatory Guide 10.8, which describes, among other things, the type of information the NRC staff needs for review of ' applications for reif.a-pharmaceutical therapy, recommends that all patient doses (both diagnostic and therapeutic) be assayed before administration to patients (i.e., independent verification of patient doses).
Licensees are required to adhere to this recommendation through a license condition.
Six of the therapy misadministrations involved the use of radiopharmaceuticals.
One of these misadministrations (22) involved an apparent misinterpretation of the physician's order by hospital personnel who ordered sodium phosphate (soluble) instead of chromic phosphate (insoluble). The activity of the misinterpreted order material was correct.
Therefore, the normally required check of the dose in a dose calibrator would not have revealed the error.
The licenset would have had to depend on labels or physical appearance to distinguish the tso radiopharmaceuticals.
Three of the radiopharmaceutical therapy misadministrations resulted.from a failure of the technologist to assay the patient doses before administration (23,24,27).
In one of these cases, the patient received a lower activity dose than prescribed.
In the two other cases, the administered activity
. differed from the prescribed activity by 10% and 30%, respectively.
Two of the radiopharmaceutical therapy misadministrations were of the types that are frequently reported for diagnostic misadministrations:
the wrong radiopharmaceutical was administered to a patient (25), and a radio-pharmaceutical was administered to the wrong patient (26).
These two types of misadministrations account for over 90% of the reported diagnostic therapy misadministrations.
Misadministration 25 involved a mixup of radio-pharmaceuticals stored in shielded containers (phosphorus-32 for iodine-131).
In misadministration 26, 8 millicuries of iodine-131 was administered to the wrong patient.
In the first case, a physician substituting for a technologist, failed to read the lable on the vial from which he drew the dose; and in the second case, the patient answered to the wrong name.
These two types of errors account for about 30% of the errors reported for diagnostic mis-administrations.
~
I.
Therapy Misadministrations Involving the Use of Brachytherapy Soteces MISAD #:
19 Type:
Dose differing from prescribed dose by >10%
l Cause:
During treatment one source slipped out of the applicator and became lodged underneath the patient.
Contributing Factors:
(1) The sources were apparently not secure in the applicator; (2) no checks were made during the treatment period to insure that i
all sources were in the applicator.
When Was Error Detected:
End of treatment period (23.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />).
How Error Was Detected:' Routine room radiation survey revealed that a source l
was missing.
Indicators of Misadministrations:
None '
Principal Licensee Personnel Involved:
Therapist Licensee's Proposed Corrective Actions:
Ovoid afterloading device will be covered with beeswax to immobilize sources.
l
==
Description:==
A patient with carcinoma of the cervix underwent intracavitary cesium application with a Fletcher Suit tandem and ovoids (four sources in the tandem and one source in each ovoid (20 mg radium equivalent in each source).
l The applicator was removed af ter 23.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.
A routine radiation protection survey of the room immediately following removal of the sources showed that a source was present in the room.
The source was subsequently found in the patient's bed.
It was believed that the source had slipped out of the tandem on removal of the afterloading device and fell underneath the patient.
Upon that patient's return for additional treatment four weeks later, it was I
discovered that a lesion (approximately 2 cm x 3 cm) with erythema and dry j
desquamation was present on her buttock.
l l
i l.
. I.
Therapy Misadministrations Involving the Use of Brachytherapy Sources (Continued)
MISAD #:
20 Type:
Dose differing from prescribed dose by >10%
Cause:
Brachytherapy sources were not placed in c erect location in Delclos applicator.
Contributing Factors:
(1) The normally round hole in the come part of the applicator was somewhat elliptical making insertion of the sources difficult; (2) the therapist did not verify the correct position of the sources at the initiation of treatment.
When Was Error Detected:
Five days after therapy was completed.
How Error Was Detected:
Inspection of appifcator af ter removal from the patient revealed change in shape in hole in dome part.
Indicators of Misadministrations:
Brachytherapy sources contained within a plastic insert had been difficult to insert into the applicator.
Principal Licensee Personnel Involved:
Therapist Licensee's Proposed Corrective Actions:
Radiation therapist and gynecologist have been given a dummy source carrier.
Before the applicator is loaded into the patient, the hole of the applicator will be checked for clearance using the dummy carrier.
==
Description:==
A patient undergoing therapy treatment of vaginal cuff following a hysterectomy for an adenocarcinoma of the endometrium was administered a dose of 1000 rads instead of a prescribed dose of 3825 rads.
The treatment used two cesium-137 sources of 30 mg radium-equivalent and 15 mg radium equivalent loaded in an applicator.
The estimated lower dose received was based on a review of the source placement in the applicator following completion of the treatment.
The therapist believes that two radioactive sources were not placed exactly at the intended location in the applicator. While loading the sources in the applicator which had been placed in the vagina, the radiation therapist experienced some difficulty inserting the active sources.
The applicator was examined and it was found that the dome part of the applicator had changed its shape from circular to somewhat elliptical.
This made the plastic tube source carrier difficult to insert into the applicator.
o :
I.
Therapy Misadministrations Involving the Use of Brachytherapy Sources (Continued)
MISA0 #:
21 Type:
Dose differing from prescribed dose by >10%
l Cause:
Delay in performance of computerized reconstruction of a volume iridium implant.
Contributing Factors:
Failure of the licensee to perform timely verification of brachytherapy dose rate.
When Was Error Detected.
After completion of treatmen't.
How Error Was Detected:
Computerized dose assessment.
Indicators of Misadministrations: 'None Principal Licensee Personnel Involved:
Therapist Licensee's Proposed Corrective Actions:
Require calculations to be checked by l
the Physics Department if computer dosimetry cannot be run within one-fourth of the task.
==
Description:==
A patient undergoing brachytherapy treatment with fridium-192 was administered a dose to the treatment area that was 12% greater than the prescribed dose.
The misadministration occurred because of a delay in determining the precise location of the implant in the tumor volume.
This led to an underestimate of the dose rate to the treatment area.
l 3.
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[ II.
Therapy Misadministrations Involving the Use of Radiopharmaceuticals 9
MISAD #:
22 TY2e:
Wrong radiopharmaceutical.
\\-
l Cause:
Error in ordering of radiopharmaceutical from supplier.-
L l
Cor.tributin'a Factors:
(1) Lack of quality control procedure to verify accuracy of form of P-32 administered; (2) material ordered by phone rather than written order.
When Was Error Detected:
Two weeks after therapy.
How Error Was Detected:
Patient chart review.
Indicators of Misadministrations:
None Principal Licensee Personnel Involved:
Technologist l
Licensee's Proposed Corrective Actions:
(1) Require therapist to review and 1
initial isotope log book before administering isotope; (2) require physicist or dosimetrist to review treatment plan and initial log book.
==
Description:==
A patient with widely disseminated nalignant melanoma with extensive brain metastases developed malignant ascites.
In an attempt to help alleviate the symptoms, on May 22 an intra-abdominal injection of 13.4 millicuries of phosphorus-32 in the form of chromic phosphate was ordered from the radiopharma-ceutical company.
Review of records'on June 5 revealed the actual injection i
consisted of the correct amount of phosphorus-32, but in the sodium phosphate form.
The chemical significance of the use of sodium phosphate instead of chromic l
phosphate results from the greater solubility of the sodium form as compared to the insolubility of the latter.
In the intended treatment with P-32' chronic i
phosphate, a substantial amount of'the radioactive P-32 is retained within the abdominal cavity until decay.
With the use of sodium phosphate, some of the P-32 will be eliminated from the body and some will enter the bloodstream.
The principal cifnical effects of the use of P-32 as sodium phosphate are a somewhat reduced ~ dose to the abdominal areas and an increased dose to the bone marrow.
Any effects on the bone marrow would appear several months'after the dose as abnormal blood parameters.
-y.
II.
Therapy Misadministrations Involving the Use of Radiopharmaceuticals (Continued) l MISAD #:
23 l
Typ_e:
Dose differing from prescribed dose by >10%
Cause:
Technologist failed to assay patient dose before to administration.
Contributina Factors: (1) Three technologists were involved in administering the dose and there was a confusion as to who should perform assay; (2) Lack of training in procedures in that the technologists were uncertain as to the requirement to assay the dose before administration.
When Was Error Detected:
One day after therapy.
l How Error Was Detected:
Patient chart review.
Indicators of Misadministrations:
None
/rfncipal Licensee Personnel Involved:
Technologist Licensee's Proposed Corrective Actions:
(1) Retrain technologists on procedures or thyroid therapies; (2) when there is more than one technologist, specify one technologist to he in charge.
==
Description:==
A patient with a diagnosis of toxic multinodular goiter was prescribed 29.9 mci of I-131'to be administered on February 22.
On that date, the patient was administered two capsules of I-131 with one capsule assayed by the supp1fer as 20 mci and the other capsule assaye,d as 8 mCl, with the assay time for both capsules being 12 noon on February 26.
While written procedures require the dose to be calculated on a dose sheet and the activity of the i
radioisotope to be measured in a dose calibrator before being administered to the patient, neither procedure was followed.
The calculation procedure was i
not followed because each of the technologists assumed another technician had performed the dose calculation and had corrected the activity to February 22.
The activity of the I-131 capsules was not measured in the dose calibrator because of the technologists' confusion in the requirements to calibrate I-131 i
therapy doses.
As a result of these two errors, the patient was given 39.5 mci of I-131 instead of the prescribed dose of 29.9 mCf.
I l
L
11.
Therapy Misadmin'strations Involving the Use of Radiopharmaceuticals (Continued)
MISAD #:
24 i
Tyge:
Dose differing from prescribed dose by >10%
Cause:
Technologist failed to assay patient dose before administration.
Contributina Factors: (1) Containers holding two capsules (5.4 mci and 0.392 mC1) were not clearly labeled; (2) capsule being stored for decay was kept in same area as usable capsules.
When Was Error Detected:
Same day or one day after therapy.
How Error Was Detected:
Patient chart review.
Indicators of Misadministrations:
None Principal Licensee Pirsonnel Involved: Technologist Licensee's is'oosed Corrective Actions:
(1) Seal therapeutic doses of I-131 not utiliiid'kithin 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the scheduled time in their container and mark "00 NOT USE"; (2) assay therapeutic doses of I-131 within 30 minutes of administration.
==
Description:==
On September 24, a patient scheduled to receive a therapeutic dose of 5.4 millicuries of fodine-131 in capsule form received a capsule of 0.392 millicurie activity.
The administering technologist took the capsule from a container containing a capsule which had been assayed at 5.2 millicuries on August 25, and was being stored for decay prior to disposal.
The technologist overlooked the unmarked container that contained the capsule intended for the patient.
. 11.
Therapy Misadministrations Involving the Use of Radiopharmaceuticals (Continued)
MISA0 #:
25 Tyfte:
Wrong radiopharmaceutical Cause:
Physician administering the dose used the wrong radiopharmaceutical storage vial to prepare the dose.
Contributino Factors:
(1) The physician who was filling in for an absent technologist had not administered therapy doses in several years and was not familiar with therapy lab and equipment; (2) the patient dose was not assayed, because physician was not familiar with sodiun: iodine scintillation counter; (3) physician failed to read, label on vial from which he drew dose.
When Was Error Detected:
Same day, shortly after dismissing the patient.
How Error Was Detected:
Physician cleaning up noticed vial was labeled P-32.
Indicators of Misadministrations:
If the patient had received the correct radiopharmaceutical, the radiation monitor positioned at the door would have alarmed as the patient left.
Principal Licensee Personnel Involved:
Physician filling in for technologist.
Licensee's Proposed Corroctive Actions:
(1) Revise protocol to insure proper training for all persons who dispense radioisotope material to patient, (2) reduce physical proximity of the two mixed-up doses (P-32. I-131).
==
Description:==
An outpatient scheduled to receive 11.0 millicuries of fodine-131 for treatment of hyperthyroidism was administered 9.85 millicuries of phosphorus-32.
The dose was prepared and administe:ed by the prescribing therapeutic radiologist.
The physician, in preparing the dose, used a vial containing phosphorus-32 thinking it to be iodine-131.
The physician stated that the personnel who normally administer the I-131 therapeutic doses were not present at the clinic.
In their absence, he proceeded to administer an I-131 dose to a patient.
The physician indicated he had not administered 1-131 therapeutic doses in several years and did not have the familiarity with the therapeutic radiology department's laboratory equipment that he had when he routinely administered I-131 years ago.
In the process of preparing the therapeutic dose in the laboratory, the physician
- II.. Therapy Misadm.nistrations Involving the Use of Radiopharmaceuticals (Continued)
MISAD #:
25 (continued) removed a vial from a lead box in an area where the I-131 had been located based on his past experience.
He stated that he was not aware that P-32 was now located in that area.
The physician did not notice that the vial was labeled P-32 because he apparently focused his attention only on the portion of the label which contained the assay information.
He did not assay'the dose after it was prepared because he was unfemiliar with the operation of the sodium iodide scintillation counter.
Subsequent to administering the dose and ',
dismissing the patient, the physician returned to the laboratory to clean up and discovered the vial was labeled P-32. A hematologist was immediately contacted for advice.
The patient was contacted and returned to the hospital about an hour later.
The patient's stomach was pumped and she 'was administered calcium carbonate and Amphogel in an effort to confine the P-32 and mitigate its effects.
After the initial interview, the physician. remembered that normally there was an erratic and loud sound from the radiation monitor (positioned at the entrance / exit of the laboratory) whenever a patient who had received 1-131 left the laboratory.
He recalled there was not any such reaction when the patient, subsequent to receiving the P-32, exited the laboratory. He indicated that, although he did not recognize it at the time, the " lack of reaction" from the monitor was an indication that the patient had not received the intended 1-131 therapy.
)
'g-
~,
II.
Therapy Misadministrations Involving the Use of Radiopharmaceuticals (Continued)
MISAD #:
26 Type _:
Wrong patient Cause:
The patient answered to the wrong name.
Contributing Factors:
The patient did not speak English (an interpreter was used).
l l
When Was Error Detected: The day af ter the therapy.
l How Error Was Detected:
The correct patient reported to the hospital for the scheduled therapy.
l Indicators of Misadministrations:
The therapy was not scheduled for the day it was performed.
Principal Licensee Personnel Involved:
Physician, Technologist Licensee's Proposed Corrective Actions:
Improve efforts to verify patient l
identity.
==
Description:==
The wrong patient received an 8 millicurie dose of iodine-131 for hyperthyrofdism.
This patient (who did not speak English) was scheduled for thyroid evaluation as an outpatient in the nuclear medicine department on March 23.
She was misidentified as another patient (who also did not speak English) who was scheduled for hyperthyroid treatment on March 24. The language barrier was cited by the hospital as the principal reason for the mistake.
The error was discovered when the correct patient reported to nuclear medicine on March 24.
The misadministered patient was contacted on that date and returned to the hospital the morning of March 25. A thyroid scan was performed and she was instructed to start taking Lugol's solution orally for the next five days.
p l
l L
k' o.
II.
Therapy Misadministrations Involving the Use of Radiopharmaceuticals (Continued)
MISAD #:
27 Type:
Dose differing from prescribed dose by >10%
Cause:
Failure to use dose calibrator.
Contributing Factors:
None When Was Error Detected:
After completion of therapy.
How Error Was Detected:
Patient chart review.
Indicators of Misadministrations:
None Principal Licensee Personnel Involved:
Technologist Licensee's Proposed Corrective Actions:
None
==
Description:==
Patient received a dose of iodine-131 for hyperthyroid treatment that exceeded the prescribed dose by more than 10%.
O O
a