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Advisory Committee on the Medical Use of Isotopes (ACMUI)

Report on Abnormal Occurrence Criteria for Medical Use

April 15, 2013

Subcommittee Members: D. Bailey; S. Langhorst, Ph.D. (Chair); S. Mattmuller; C. Palestro, 

M.D.; B. Thomadsen, Ph.D.; L. Weil; J. Welsh, M.D.

Charge: To review the refined abnormal occurrence criteria for events involving patients or human 

research subjects and to provide recommendations to the NRC staff.

Recommendations:

The following changes are recommended to Appendix A: Abnormal Occurrence 

Criteria in the current Abnormal Occurrence Revised Policy Statement1.

1. In section I. A., add new paragraph 4. to read as follows:

4. These criteria do not apply to events included in criteria III.C. involving medical 

administrations using byproduct material to patients or human research subjects.

2. In section III. C., redefine title; replace paragraphs 1. and 2. with the following 

paragraphs 1. and 2.:

C. For Events Involving Patients or Human Research Subjects

1. Medical event involving a patient or human research subject that, as 

determined by a consultant physician(s) deemed qualified by NRC or an 

Agreement State, results in one or more of the following:

a. Unintended or unexpected permanent functional damage to an organ.

b. Unintended or unexpected permanent functional damage to a 

physiological system.

c. A significant unexpected adverse health effect.

d. Death.

 1 Nuclear Regulatory Commission, “Revised Policy Statement on Abnormal Occurrence Criteria,” 71 FR 60198, 

October 12, 2006, http://www.gpo.gov/fdsys/pkg/FR-2006-10-12/pdf/E6-16871.pdf (accessed March 25, 2013).
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2. Notification under 10 CFR 35.3047 of an event involving an unintended dose 

to an embryo/fetus or a nursing child that results in a significant adverse 

health impact to the embryo/fetus or child, as determined by a consultant 

physician(s) deemed qualified by NRC or an Agreement State.

Need for Medical Abnormal Occurrence Criteria Update:

The Nuclear Regulatory Commission (NRC) is required to annually report abnormal 

occurrences to Congress as defined in Section 208 of the Energy Reorganization Act of 19742. This 

section states:

“For the purposes of this section an abnormal occurrence is an unscheduled incident or event 

which the Commission determines is significant from the standpoint of public health or 

safety.”

Establishment of the NRC Policy Statement on Abnormal Occurrence Criteria3 provides 

explanation of how the Commission determines the incidents or events to be significant and 

included in the annual abnormal occurrence (AO) report. The NRC Staff and the Advisory 

Committee on the Medical Use of Isotopes (ACMUI) have discussed concerns that the medical userelated incidents and events being included in AO reports may not be significant from the 

standpoint of public health or safety. During an ACMUI teleconference in December 20114, the 

ACMUI endorsed their 2008 position, which is summarized by the following: AOs for medical

licensees should be events which result in death or threaten life; AOs should not capture those 

occurrences that are accepted risks of the treatment; AOs should be of significant adverse effect; 

AO criteria should be qualitative and not quantitative5.

At the September 2012 ACMUI meeting6

 2 U.S. Energy Reorganization Act of 1974, as Amended (Public Law 93-438), pages 252-253, 

http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0980/v1/sr0980v1.pdf#page=241 (accessed March 25, 

2013).

, the NRC Staff asked the Committee to consider 

their proposal to add dose-based criteria for medical licensee AO criteria (see Attachment 1) to 

allow the NRC Staff a screening tool to decide which medical events should then be evaluated by a 

consultant physician to determine significant adverse effect. During discussion of this proposal, the 

ACMUI again voiced their concerns of using dose-based criteria to judge medical AOs. The 

ACMUI established a subcommittee to develop recommendations concerning the AO criteria 

related to medical use incidents and events.

3 Nuclear Regulatory Commission, “Revised Policy Statement on Abnormal Occurrence Criteria,” 71 FR 60198, 

October 12, 2006, http://www.gpo.gov/fdsys/pkg/FR-2006-10-12/pdf/E6-16871.pdf (accessed March 25, 2013). 4 Official Transcript of Proceedings, Nuclear Regulatory Commission Advisory Committee on the Medical Use of 

Isotopes Teleconference, December 15, 2011, http://pbadupws.nrc.gov/docs/ML1206/ML12062A278.pdf (accessed 

March 25, 2013).

5 Meeting Summary, Nuclear Regulatory Commission Advisory Committee on the Medical Use of Isotopes 

Teleconference, December 15, 2011, http://pbadupws.nrc.gov/docs/ML1135/ML11355A253.pdf (accessed April 4, 

2013).

6 Official Transcript of Proceedings, Nuclear Regulatory Commission Advisory Committee on the Medical Use of 

Isotopes Teleconference, September 21, 2012, http://pbadupws.nrc.gov/docs/ML1232/ML12324A222.pdf (accessed 

April 4, 2013).
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Development of Recommendations:

The Subcommittee reviewed medical use-related abnormal occurrences reported to Congress 

in the past five years, as summarized in this table, discussed the NRC Staff’s proposed criteria, and 

came to the conclusions as described here. Additional Subcommittee discussion points pertinent to 

these conclusions are included in Attachment 2.

Abnormal Occurrences Reported to Congress

FY All AO

AO I.A.2. 

from 

Medical Use

AO III.C. 

from 

Medical Use

20117 24 2 19

20108 15 3 12 

20099 9 2 7

200810 10 2 8 

200711 11 1 10

 Each AO listed here involved one I-131 therapy patient who was found to be in early 

stage pregnancy following her therapy. No medical licensee reported more than one patient.

 Each AO listed here involved one or two radiation therapy patients per medical licensee,

except as noted.

 One AO in this total involved three or more radiation therapy patients at one medical 

licensee.

 7 NUREG-0090, Vol. 34, “Report to Congress on Abnormal Occurrences – Fiscal Year 2011,” Nuclear Regulatory 

Commission, http://pbadupws.nrc.gov/docs/ML1214/ML12142A194.pdf (accessed March 25, 2013). 8 NUREG-0090, Vol. 33, “Report to Congress on Abnormal Occurrences – Fiscal Year 2010,” Nuclear Regulatory 

Commission, http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0090/v33/sr0090v33.pdf (accessed March 

25, 2013).

9 NUREG-0090, Vol. 32, “Report to Congress on Abnormal Occurrences – Fiscal Year 2009,” Nuclear Regulatory 

Commission, http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0090/v32/sr0090v32.pdf (accessed March 

25, 2013).

10 NUREG-0090, Vol. 31, “Report to Congress on Abnormal Occurrences – Fiscal Year 2008,” Nuclear Regulatory 

Commission, http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0090/v31/sr0090v31.pdf (accessed March 

25, 2013).

11 NUREG-0090, Vol. 30, “Report to Congress on Abnormal Occurrences – Fiscal Year 2007,” Nuclear Regulatory 

Commission, http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0090/v30/sr0090v30.pdf (accessed March 

25, 2013).
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Title Change for Medical Use AO Criteria

The Subcommittee agreed with the NRC Staff’s proposed medical use AO criteria title, “For 

Events Involving Patients or Human Research Subjects.” This title change makes clear that these 

AO criteria refer only to incidents related to medical administrations using byproduct materials, and 

that other parts of a medical licensee’s program are subject to the other AO criteria applicable to 

material licensees.

Use of Screening Criteria for Medical Use AO Criteria

At the September 2012 ACMUI meeting

12, the NRC Staff voiced concern that without dosebased AO criteria, all medical events may require the NRC to have every medical event reviewed 

by a medical consultant, resulting in significant costs and time delays. The Committee’s 

discussions at that meeting and continued discussions by the Subcommittee led the Subcommittee to 

conclude that dose-based screening criteria would not provide the NRC Staff a reliable method to 

identify medically significant incidents in all cases and therefore should not be included in the AO 

criteria.

The Subcommittee discussed the NRC Staff’s request to establish screening criteria for 

identifying those medical events that require an additional medical consultant review. ACMUI’s

annual review of the medical events and the Subcommittee’s review of the AO reports for the past 

five years indicate there are few medical events reported each year that have the potential to cause

significant harm. The Subcommittee believed that requiring an additional medical consultant 

review of every medical event to determine the significance of the event would be an unnecessary 

expenditure of resources. The Subcommittee explored the use of alternative screening criteria, such 

as setting a minimum number or rate of individuals significantly harmed by a medical event(s)

reported by a medical licensee in one AO report year (see Attachment 2, Discussion Points 2 and 3 

for additional information on these discussions). The NRC Staff informed the Subcommittee that a

screening criterion using a threshold number of individuals would not be acceptable from a 

regulatory point of view. In addition, the Subcommittee was unable to come to a unanimous 

consensus on what the threshold number of individuals should be for an AO definition.

The Subcommittee concluded that there are no practical and implementable screening 

criteria which could be included with the NRC Staff’s proposed AO criteria definition of significant 

harm (see Attachment 1, Item 2). However, the Subcommittee suggested that the NRC Staff could 

rely on the existing NRC policy regarding the use of medical consultants13 as a reasonable and 

practical screening tool to determine the need for a consultant physician (see Attachment 3).

 12 Official Transcript of Proceedings, Nuclear Regulatory Commission Advisory Committee on the Medical Use of 

Isotopes Meeting, September 21, 2012, http://pbadupws.nrc.gov/docs/ML1232/ML12324A222.pdf (accessed March 25, 

2013).

13 NRC Inspection Manual Chapter 1360: “Use of Physician and Scientific Consultants in the Medical Consultant

Program”, IMC 1360-04.02, November 2, 2006, http://pbadupws.nrc.gov/docs/ML0627/ML062720195.pdf (accessed 

March 25, 2013).
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Embryo/Fetus or Nursing Child Dose

The Subcommittee also reviewed the reporting criteria of abnormal occurrences involving 

medical licensee notification of unintended dose to an embryo/fetus or nursing child. The past five

years of AO reports included notifications of unintended dose to an embryo/fetus that were due to I131 therapy patients unknowingly being pregnant at the time of their therapy despite appropriate 

pre-treatment pregnancy screening. These incidents were reported as abnormal occurrences due to 

the low dose threshold criterion defined the “For All Licensees” AO criteria I.A.3. 

The Subcommittee did not believe use of the “For All Licensees” criteria I.A.3 is 

appropriate in judging a medical use AO, even though dose to the embryo/fetus or child may be

considered a public dose. The Subcommittee considered it inappropriate because the mother is 

undergoing a medical treatment and the unintended dose to the embryo/fetus or child should not be 

considered separate from the medical administration. In a regulatory sense, this is consistent with 

how the NRC requires embryo/fetus or nursing child dose reporting to be done under the medical 

use regulations14 rather than under the protection against radiation regulations15

 14 10 CFR 35.3047, “Report and notification of a dose to an embryo/fetus or a nursing child,” 

http://www.nrc.gov/reading-rm/doc-collections/cfr/part035/part035-3047.html (accessed March 25, 2013).

. The 

Subcommittee recommended that the “For All Licensees” AO criteria I.A. be modified to exclude 

events that are included in criteria III.C involving medical administrations using byproduct material 

to patients or human research subjects. This recommended modification is made in a similar way 

the “For All Licensees” criteria I.B. excludes transportation events. The Subcommittee 

recommended that the AO criteria III.C. also include the unintended dose reported under 10 CFR 

35.3047 to an embryo/fetus or a nursing child which results in a significant medical harm to the 

embryo/fetus or child because this abnormal occurrence can only happen as a result of medical 

administration to a patient or human research subject. 

15 10 CFR 20.2203(a)(2)(iv), “Reports of exposures, radiation levels, and concentrations of radioactive material 

exceeding the constraints or limits,” http://www.nrc.gov/reading-rm/doc-collections/cfr/part020/part020-2203.html 

(accessed March 25, 2013).
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Attachment 1

Medical AO Draft Criteria Discussed at the September 2012 

ACMUI Meeting

For Events Involving Patients or Human Research Subjects 

1. A medical event that results in an unintended dose to the target or a dose other than the dose to 

the intended target that is:

a. Greater than or equal to 1 Gy (100 rad) to a major portion of the bone marrow or to the 

lens of the eye; or

b. Greater than or equal to 2.5 Gy (250 rad) to the gonads; or

c. Greater than or equal to 10 Gy (1,000 rad to any other unintended organ or tissues other 

than the treatment site; and

2. Results in a significant impact on patient health that would result in one or more of the 

following, as determined by a consultant physician(s) deemed qualified by NRC or an 

Agreement State:

a. Unintended or unexpected permanent functional damage to an organ.

b. Unintended or unexpected permanent functional damage to a physiological system. 

c. A significant unexpected adverse health effect.

d. Death
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Attachment 2

Additional Subcommittee Discussion Points 

Concerning Medical Use Abnormal Occurrence Criteria

In developing recommendations for medical use abnormal occurrence (AO) criteria, the 

Subcommittee discussed the following points.

1. What is the difference between medical events or notifications of embryo/fetus or child 

dose versus abnormal occurrences?

The Subcommittee recognized that regulations for medical events and notifications 

of unintended embryo/fetus or child dose provide indicators of errors in a medical 

administration using byproduct materials worthy of close evaluation by the licensee 

and the regulators. The fact that these incidents may not be considered abnormal 

occurrences does not diminish the seriousness of the incident, the requirements to 

evaluate cause and corrective action, or the need for regulatory enforcement. 

Medical licensees have demonstrated a good safety record with low incident rates

less than 0.3 % for medical events affecting the medical treatment of 50 to 100 

patients a year16. In most cases, these medical events do not result in a significant 

adverse effect to the patient or human research subject. 

In the end, the Subcommittee distinguished regulatory criteria defining medical 

events and notifications of unintended embryo/fetus or child dose as being chosen to 

protect the individual member of the public, while AO criteria are used to define 

which of these medical events and notifications should be considered as significant 

from the standpoint of public health and safety for the annual report to Congress.

2. Could a minimum number of medical use-related event reports per licensee to be 

considered as a screening criterion for abnormal occurrence definition?

The Subcommittee explored the meaning of “public health or safety” used in the 

definition of an abnormal occurrence by considering the definitions of the following 

terms:

 16 Byproduct Material Events Subcommittee Report, Nuclear Regulatory Commission Advisory Committee on the 

Medical Use of Isotopes Meeting, April 2011, http://pbadupws.nrc.gov/docs/ML1109/ML11095A086.pdf (accessed 

April 4, 2013).
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Public17

1. of, belonging to, or concerning the people as a whole; of or by the 

community at large

–

3. as regards community, rather than private, affairs

Public Health18

The science and practice of protecting and improving the health of a 

community, as by preventive medicine, health education, control of 

communicable diseases, application of sanitary measures, and monitoring of 

environmental hazards.

–

Public Health Ethics19

Public health ethics involves a systematic process to clarify, prioritize and 

justify possible courses of public health action based on ethical principles, 

values and beliefs of stakeholders, and scientific and other information.

-

The Subcommittee considered that incidents or events should have the potential for 

significant medical harm to more than one individual to be considered as significant 

from a public health or safety standpoint. The NRC has used this sort of threshold 

criteria for determining whether an Incident Investigation Team (IIT) or an 

Augmented Inspection Team (AIT) is warranted for a Medical Event Assessment 

(MEA)20.

The Subcommittee discussed what might be an appropriate number of individuals for 

a threshold criterion. One Subcommittee member felt any number greater than one 

would not be acceptable because of the adverse medical consequence criteria. 

Another Subcommittee member suggested two individuals would be the appropriate 

threshold criterion because one adverse event could happen anywhere, and not 

signify a threat to public health, but a second similar adverse event could indicate a 

failure in the cause analysis and correction process. The remaining Subcommittee 

members thought three individuals would be an appropriate threshold criterion, but

also suggested that the Commission should consider providing summary information 

of medical use-related events resulting in medical harm not meeting this AO 

criterion as part of the AO report under the AO criteria IV. Other Events of Interest.

The NRC Staff told the Subcommittee that this sort of screening criterion would not 

be acceptable from a regulatory point of view. They noted that the regulatory 

philosophy of the NRC considers harm to any individual. As noted in Discussion 

Point 1, every medical event is subject to regulation and therefore no event posing 

harm to an individual would avoid regulatory scrutiny. The majority of 

 17 Webster’s New World College Dictionary, http://www.yourdictionary.com/public (accessed March 25, 2013). 18 The American Heritage® Medical Dictionary, http://medical.yourdictionary.com/public-health (accessed March 25, 

2013).

19 Centers for Disease Control and Prevention, http://www.cdc.gov/od/science/integrity/phethics/ (accessed March 25, 

2013)

20 NRC Medical Event Assessment Program Directive 8.10, July 6, 1994, 

http://pbadupws.nrc.gov/docs/ML0414/ML041410592.pdf (accessed April 8, 2013)
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Subcommittee members did not see a conflict between using a threshold number of 

individuals as a screening criterion and the NRC’s regulatory philosophy.

3. Could a measure of rate be used rather that an absolute number of events reported in 

a year by a medical licensee?

The Subcommittee discussed whether consideration should be included for an AO 

criterion that evaluates the difference between a small clinic medical licensee 

reporting multiple events out of a low number of medical administrations a year 

versus a large university hospital medical licensee reporting the same number of 

events out of a much higher number of medical administrations. The Subcommittee 

concluded that use of a rate-based AO criterion would be impractical because 

medical licensees are not required to report the number of medical administrations 

per year. The Subcommittee did recognize that the evaluation of this kind of event 

rate is an important aspect of the NRC or Agreement State inspection of the medical 

licensee’s compliance and subsequent enforcement actions.
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Attachment 3

NRC INSPECTION MANUAL

Manual Chapter 1360

Use of Physician and Scientific Consultants

in the Medical Consultant Program

(http://pbadupws.nrc.gov/docs/ML0627/ML062720195.pdf)

1360-04 POLICY ON USE OF MEDICAL CONSULTANTS

04.01 The time frame for initial activation of the procedures in this Manual Chapter should be 

based on the initial assessment of the severity of the event. This assessment will typically be 

performed by the regional office with input from MSSA/FSME, as necessary.

The following guidelines may be used when establishing the time frame for activation1

:

a. Radiation Exposure Incident resulting in a fatality - 2 working days after NRC is informed 

of the event.

b. Radiation Exposure Incident determined to:

1. be a medical event; and

2. result in a total dose in excess of the prescribed total dose to a patient – 5 working 

days after the event is determined to be a medical event by NRC.

c. Radiation Exposure Incident determined to: 

1. be a medical event where the reporting requirement was based on the fractionated 

dose; and

2. result in an overexposure that exceeds the prescribed total dose or three times the 

fractionated dose, whichever occurs first - 10 working days after the event is 

determined to be a medical event by NRC.

d. Radiation Exposure Incident (other than a medical event) that has not resulted in a fatality -

10 working days after NRC is informed of the event.

 1 The specified time frame assumes that the radiation exposure incident occurred within the last 2 months. If the 

radiation exposure incident occurred in the past, consideration should be given to extending the time frame.
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04.02 Medical Consultants must be used under the following circumstances:

a. Incidents where an individual has received one or more of the following doses:

1. A suspected total effective dose equivalent of 0.25 sievert (Sv) (25 rem) or more.

2. A suspected lens of the eye dose equivalent of 0.75 Sv (75 rem) or more.

3. A shallow-dose equivalent to the skin or extremities of 2.5 Gray (250 rad or more.

4. A suspected committed effective dose of 2.5 Sv (250 rem) or more to any individual 

organ or tissue other than the lens of the eye.

b. Incidents where an individual is demonstrating physical symptoms (erythema, nausea, 

vomiting, etc.) consistent with radiation syndromes, and the source of the radiation may be 

attributable to NRC-licensed radioactive material.

c. Incidents where NRC staff believe permanent functional damage to an organ or a 

physiological system is possible.

d. Incidents where a nursing infant or an embryo/fetus may have been inadvertently exposed to 

radiation or radioactive material as a result of the intentional or unintentional exposure of 

the mother of the nursing infant or an embryo/fetus to radiation or radioactive material.

e. A medical consultant shall be contacted for all medical events involving an overexposure in 

accordance with Management Directive 8.10, “NRC Medical Event Assessment Program.” 

With the exception of the case identified in item c. above (for which site visits are required), 

a site visit by the medical consultant will not normally be required. A site visit by the 

medical consultant would be appropriate if the region and consultant agree that a site visit is 

necessary for NRC to understand the event, its causes, and its ramifications to the NRC’s 

programs. Section 05.04e describes documentation required when the medical consultant

determines that a site visit or consulting services are not necessary.

04.03 Medical Consultants may be used under the following circumstances:

a. Incidents where members of the public or occupationally exposed individuals may have 

been exposed to radiation during a radiation exposure incident.

b. Incidents where the staff believes that the assistance of a medical consultant would be 

beneficial to fulfilling the NRC mission.