RIS 2005-24, Control of Radiation Dose to Visitors of Hospital Patients: Difference between revisions

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Revision as of 07:49, 5 March 2018

Control of Radiation Dose to Visitors of Hospital Patients
ML052840388
Person / Time
Issue date: 11/23/2005
Revision: 0
From: Holahan P K, Miller C L
NRC/NMSS/IMNS
To:
Shebini S
References
RIS-05-024
Download: ML052840388 (12)


UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDSWASHINGTON, D.C. 20555November 23, 2005NRC REGULATORY ISSUE SUMMARY 2005-24 CONTROL OFRADIATION DOSE TO VISITORS OF HOSPITAL PATIENTS

ADDRESSEES

All medical licensees.

INTENT

The U.S. Nuclear Regulatory Commission (NRC) is issuing this regulatory issue summary (RIS)to provide guidance on methods that may be used to estimate and control radiation doses to visitors of hospitalized patients who have been administered radioactive materia Guidance is also provided on information collection in visitor exposure cases requiring dose reconstructio No specific action nor written response is required.

BACKGROUND

In 2002, several members of the public were inadvertently permitted to receive radiation dosesin excess of the regulatory limi The individuals received the doses when they visited a family member who was confined to the hospital after receiving radioactive materia The licensee was not required to individually monitor the doses received by each of the visitors, and none of the visitors were provided with dose-monitoring device The licensee was required, however, to perform surveys and take other measures to ensure that none of the visitors received a dose in excess of the dose limit for a member of the publi The licensee discovered the inadvertent exposures a few weeks after they had occurred, and it attempted to estimate the doses receive However, lacking the data to accurately and directly assign doses to the visitors, it was necessary to retrospectively estimate the doses using a combination of survey data, records of radioactive material administration, interviews with persons involved with the case, and dose calculation Because these efforts were initiated a considerable time after the exposures had taken place, there were uncertainties regarding the details of the case and the conditions under which the exposures occurre The final dose estimates necessarily reflected these uncertainties, and consequently involved wider margins of uncertainty than are normally desirable in such assessments.The NRC identified several factors that indicated a lack of sufficient awareness of the status ofthe visitors' accumulated doses during the visits to ensure compliance with applicable regulations, including applicable dose limit A contributing factor that resulted in a dose above the applicable limit in the case of at least one of the visitors was a reluctance, on the part of the visitor, to comply with the licensee's instructions that were designed to minimize these dose Important questions also arose regarding the use of data obtained from radiation surveysconducted in the patient's room to retrospectively estimate the doses received by the visitor These concerns prompted an examination of the methods that may be used in controllingexposures of visitors, and in estimating the doses they receive during these visit This RIS provides some guidance in these areas.

SUMMARY OF ISSUE

Patients undergoing nuclear medicine procedures, either diagnostic or therapeutic, as well aspatients with brachytherapy implants, may be released from the hospital only if they meetcertain conditions specified in NRC's regulations [10 CFR 35.75]. Patients failing to meet theseconditions must be kept in the hospital until the radiation fields emanating from them diminish tothe point where they meet the release conditions.During their confinement in the hospital, patients are usually visited by family members andfriend Such visitors are considered to be members of the public, subject to the dose limits applicable to members of the public [10 CFR 20.1301]. The hospital's radiation protection staff are required to ensure that doses do not exceed these limits, and that all reasonable measuresare taken to keep doses ALARA, given the circumstances of the cas Ensuring compliance with the dose limits implies that either the licensee has prospectively determined that conditionscannot lead to doses in excess of the limit, or the accumulated dose to date for each visitor is monitored, and appropriate controls are imposed based on the degree to which the accumulated dose approaches an action level or a limi It should be pointed out that the success of these controls depends on the cooperation of the visitors and on their compliancewith the licensee's instructions for minimizing the doses receive In many situations involving exposure of visitors in patient rooms, the visitors are not providedwith radiation-monitoring devices, such as self-reading pocket dosimeters, to measure the doses they receive during the visits, nor is such monitoring required by regulatio This is adequate if it is prospectively determined that the doses to visitors, under the specific conditions of the case, are unlikely to exceed any limit or action leve Otherwise, the hospital radiation protection staff should either issue personnel-monitoring devices to the visitors or must rely on the radiation survey data routinely conducted in the patient's room to estimate and monitorvisitor doses in real tim Under certain conditions, and where adequate data are available, the doses received by the visitors may be calculated, but such calculations are complex, require a considerable amount of input data, and are normally performed only if it becomes necessary to undertake a retrospective dose assessmen The calculations are generally not suitable for controlling an ongoing exposure situation.This RIS discusses some of the measures that may be used to maintain control and minimizedoses to visitors, and also discusses the types of information that may be needed if a retrospective dose assessment becomes necessar In addition, it provides guidance on the use of radiation survey data to estimate visitor doses in those cases where visitors are not provided with personnel-monitoring device This discussion and guidance is provided in the Appendix to this RI

FEDERAL REGISTER NOTIFICATION

A notice of opportunity for public comment on this RIS was not published in the FederalRegister because it is informational, and does not represent a departure from current regulatoryrequirements.SMALL BUSINESS REGULATORY ENFORCEMENT FAIRNESS ACT NRC has determined that this action is not subject to the Small Business RegulatoryEnforcement Fairness Act of 1996.

PAPERWORK REDUCTION ACT STATEMENT

This RIS does not contain information collections and, therefore, is not subject to therequirements of the Paperwork Reduction Act of 1995 (44 U.S.C., 3501 et seq).This RIS requires no specific action or written respons If you have questions about theinformation in this summary, please contact one of the technical contacts listed below, or the appropriate regional office.Patricia K. Holahan, for /RA/Charles L. Miller, Director Division of Industrial and Medical Nuclear Safety Office of Nuclear Material Safety and Safeguards

Attachments:

Appendix: Controlling Visitor Exposures "List of Recently Issued NMSS Generic Communications"Technical Contacts:

Sami Sherbini, NMSSJoseph E. DeCicco, NMSS Thomas H. Essig, NMSS(301) 415-7853(301) 415-7833 (301) 415-7231 E-mail: sxs2@nrc.govE-mail: jxd@nrc.gov E-mail: the@nrc.gov

FEDERAL REGISTER NOTIFICATION

A notice of opportunity for public comment on this RIS was not published in the FederalRegister because it is informational, and does not represent a departure from current regulatoryrequirements.SMALL BUSINESS REGULATORY ENFORCEMENT FAIRNESS ACT NRC has determined that this action is not subject to the Small Business RegulatoryEnforcement Fairness Act of 1996.

PAPERWORK REDUCTION ACT STATEMENT

This RIS does not contain information collections and, therefore, is not subject to therequirements of the Paperwork Reduction Act of 1995 (44 U.S.C., 3501 et seq).This RIS requires no specific action or written respons If you have questions about theinformation in this summary, please contact one of the technical contacts listed below, or the appropriate regional office.Patricia K. Holahan, for /RA/Charles L. Miller, Director Division of Industrial and Medical Nuclear Safety Office of Nuclear Material Safety and Safeguards

Attachments:

Appendix: Controlling Visitor Exposures "List of Recently Issued NMSS Generic Communications" Technical Contacts:

Sami Sherbini, NMSSJoseph E. DeCicco, NMSSThomas H. Essig, NMSS (301) 415-7853(301) 415-7833(301) 415-7231 E-mail: sxs2@nrc.govE-mail: jxd@nrc.gov E-mail: the@nrc.govG:\sherbini\ris.wpdOFFICEMSIBNMSSMSIBIMNSIMNSNAMESSherbiniEKrausRCorreiaTEssigCMiller DATE6/16/056/15/05 6 6/20/056/20/0510/5/05OFFICEOGCOGC:SBREFAOIS/PRA NAMES.TrebyT.RothschildB.SheltonDATE10/24/0511/16/0511/10/05OFFICIAL RECORD COPY Attachment 1 APPENDIXCONTROLLING VISITOR EXPOSURES:To assist in maintaining compliance with regulatory requirements, and in assessing doses tovisitors when necessary, the following measures are recommended:1.It has sometimes proven useful to mark the floor of the patient's room with clearly visible tape of an appropriate color to indicate areas where visitors may stand or sit without being in excessively high-dose-rate area Conversely, appropriately colored tape may be used to indicate areas that visitors should not enter, or should avoid whenever possible, because of high dose rates. 2.In planning for visitor exposures and for performing surveys, consideration should begiven to the fact that the radiation fields around the patient could vary rapidly withlocation around the patient, depending on where the radioactive material is located within the patient's body and the nature and energy of the radiatio Frequently, theradiation field may be much higher on one side of the patient, compared with the other sid In nuclear medicine procedures, consideration should also be given to the fact that the radioactive material will generally move inside the body, with time, afteradministration of the dos This movement within the body could cause significant changes over time in the radiation fields surrounding the patient, and therefore to the doses received by visitor The distribution of radiation fields around the patient can be easily and quickly determined by appropriate surveys using a standard survey instrumen Survey locations and frequencies should be planned to identify these changes as they occur, allowing timely action in controlling visitor activities.3.In cases where it is anticipated that the dose to a visitor will approach a substantialfraction of the applicable limit, it is important to increase control of exposures to avoid exceeding that limi The limit is normally 0.1 cSv (0.1 rem), but in some cases may be 0.5 cSv (0.5 rem) or a higher pre-approved valu In such cases, it is usually prudent to provide affected visitors with self-reading pocket dosimeters that are checked periodicall These periodic dosimeter readings are added to previous readings to obtain each visitor's total dose to dat The reading of the dosimeter in roentgen or rad in such cases may be taken as a sufficiently accurate indicator of the person's dose in re Action must be taken if the running total dose for any visitor approaches a pre- established action leve These actions may be, for example, attempting to restrict visit durations or frequency, increasing the use of shielding, and/or confining the visitor to locations within the room that are not too close to the patien An alternative approachto keeping a running total dose might be to attempt to restrict the total duration of all visits by a visitor to a time period based on a conservative estimate of the dose rate to which the visitor may be expose The time period would be chosen such that the total dose received during that period, assuming a conservatively high dose rate, will not cause any dose limit to be exceede Additional measures might include increasedsurveillance by the radiation protection staff, and training of the visitor in ways to Attachment 1 minimize radiation exposur If for any reason it appears that a visitor's dose mayexceed the applicable regulatory limit, the licensee should notify the NRC promptly to considerappropriate measure Notification of the NRC is required if the dose has, or may have,exceeded any applicable limi It should be noted that attempts to control visitor activities, such as restricting visit frequency and duration, may in some cases be difficult or impossible if the visitor refuses to cooperat Explaining the risks from radiation exposure and the need tokeeps doses within regulatory limits for health and safety reasons may be useful in some case However, as indicated above, the licensee should immediately notify the NRC if a situationdevelops in which a failure by a visitor to follow the licensee's instructions could to lead to doses that exceed the applicable regulatory limit. 4.Some licensees have adopted the practice of routinely issuing self-reading pocketdosimeters to all visitors who enter the patient's room, even in those cases where the doses received by the visitors are not expected to be significan This practice has many advantages, including providing reliable control and easy monitoring of visitor doses, as well as producing a reliable record showing compliance with applicable limit This option may be especially attractive if the licensee already uses such dosimetry for other purposes, but may be expensive to implement if the dosimetry is not already in use at the facility.5.If it appears, in prospective assessments, or in re-evaluations during the visiting period,that circumstances are such that it may not be feasible to remain within the regulatorylimit for some of the visitors, then several actions should be considere The NRC Regional Office, or equivalent State regulatory authority, should be immediately notifiedof the situation and guidance sought on the appropriate regulatory mechanisms to beused for that situatio Close monitoring of the visitor using a self-reading dosimeterwould be advisabl The key elements in these measures are that visitor doses should be estimated prospectively, and that dose trends be carefully monitored and action taken before any pre-established action level or limit is reache .In the case of unsealed sources, such as those used in nuclear medicine procedures,there is the potential that the patient's room may become contaminate Thecontamination may be on surfaces, or it may be airborn The licensee should determine, in any given case, whether there exists a potential for such contaminatio Ifthere is such a potential, then appropriate surveys may be required to establish if the contamination exists, and if so, its magnitud Should it be determined that visitors mayhave been exposed to unsealed radioactive material, suitable measurements and internal dose calculations should be considered, and the calculated internal doses added to the external doses to estimate the visitor's total effective dose equivalent (TEDE), to show compliance with 10 CFR Part 20 dose limits.DATA COLLECTION IF RETROSPECTIVE DOSE ASSESSMENT IS ANTICIPATED:A detailed retrospective dose assessment should be considered whenever available information suggests that the dose to any person may have exceeded an applicable limit, and when there isinsufficient reliable data to directly assign a dose to the exposed visito The type of Attachment 1 assessment will depend in part on the degree to which the dose may have exceeded the limit,and also on the type and quality of the data available on which to base the assessmen Estimating dose retrospectively may be as simple as reviewing survey or dosimeter readings, if such data are of adequate quality and quantit Alternatively, and especially if the measurements are inadequate or if the dose received may be high, calculations may be performed to estimate the doses. The success and accuracy of any retrospective analysis depends on the availability of adequateinformation and data to permit a reliable reconstruction of the exposure situation and reasonably accurate estimation of the resulting dos Therefore, as soon as it is realized that a retrospective dose assessment may be required, the licensee should assemble as much relevant information on the case as is possibl The types of information that should be assembled include, but are not limited to, the following:a.All relevant survey data, including the survey readings, location of each survey, the timeand date each survey was conducted, the type of instrument used, and the name of theperson who conducted the surve The models and serial numbers of the instruments used should be recorded, as well as the calibration date and calibration due date for each instrument. b.If the affected persons were monitored with personal dosimeters, then the readings ofthe dosimeters should be provided, as well as the calibration certificates, the processorreports if the dosimeters were processed, and descriptions of where the dosimeters were placed on the monitored persons.c.Details on the radioactive material involved, activity or amount administered (orimplanted), date and time of administration, and initial surveys after administratio For implants, their shapes, sizes, and locations should additionally be provide d.Data on excretion of radioactive material by the patient if the material was administeredin unsealed for Although excreta are not normally collected and analyzed, any data on excretion patterns that may be available would be usefu These data may include volumes excreted (fecal and urinary), how collected, activity contained in the excreta or a measurement of the radiation fields emitted by these excreta, date and time excreted,and any surveys performed on the excret This type of information may help in retrospective assessment by permitting a better estimate of the amount of radioactive material that was retained in the patient's body during various periods of visitor exposures.e.As much detail as possible on the movements of the exposed persons during theperiods of exposur This would include location with respect to the patient; time spent; and orientation with respect to the patient, (e.g. facing the patient and leaning on thebed, sitting on a chair, with side to the patient, and so on).

f.In the case of unsealed sources, any information that is useful for understand the Attachment 1 distribution of the radioactive material in the patient's body as a function of tim Thismay be obtained from the medical staff and/or the results of radiation surveys conducted close to the patien The patient's medical condition at the time maysignificantly alter the pattern distribution and excretion of radioactivity, and this should be taken into account.g.Detailed records and notes of any interviews that may have been conducted withaffected persons, including the exposed persons, other visitors, and licensee and other staf These interviews should be conducted as promptly as possible after the decision is made to retrospectively estimate doses.h.Any information that indicates the level of contamination in the patient's room or thatindicates the absence of such contaminatio The information could also include any data from bioassays that may have been performed on a visitor.The above information may not be needed in all cases involving retrospective doseassessmen However, the licensee should judge the scope of the expected assessments and collect the information as appropriat The information should be collected promptly, because delays will blur recollections, and certain information may be short-lived, and may not beavailable if collection of that information is delaye In addition, certain tests, such as internal contamination measurements, may not be possible after a certain time period has elapsed after the exposur If these tests are to be successful, the decision to order them must be made soon after the exposures.It should be clear from the above that mechanisms should be in place that promptly alert thelicensee of an event that would initiate data collection and preparations for retrospective assessment A procedure should also be in place to indicate the types of information to be assembled. ESTIMATING VISITOR DOSES USING SURVEY DATA:In February 2003, NRC issued a RIS entitled, "Use of the Effective Dose Equivalent in Place ofthe Deep Dose Equivalent in Dose Assessment" [RIS 2003-04]. This RIS encouraged licensees, in certain situations, to use the effective dose equivalent in place of the deep dose equivalent (DDE) in the 10 CFR Part 20 definition of the total effective dose equivalent ( TEDE).

The reason was that in situations other than uniform whole body exposures, the effective doseequivalent is more closely related to the risks from radiation exposures than is the DD Theaforementioned RIS noted that the guidance applies to all situations except those involvingmonitoring of individuals using personal dosimetr This exception arises from the fact that special methods are required for interpreting the dosimetry results, so as to obtain reliable estimates of the effective dose equivalent, and the NRC reserved the right to approve each ofthese methods individually before authorizing its use.The effective dose cannot be measured directly, and it is therefore necessary to estimate itsvalue in any given situation on the basis of an appropriate measured quantit In many situations involving visitor exposures, the only available measured quantity is the exposure rate, in roentgens (R) per hour, obtained from the required periodic surveys of the patient's room.Attachment 1 To determine the relationship of the survey readings to visitor dose, NRC has made detailedcalculations of the radiation fields around a patient lying on a hospital bed and containingradioactive material administered during nuclear medicine or brachytherapy procedure The calculations estimated the relationship between the readings of a survey instrument, in R/hr, at specified locations around the bed, and the effective dose rate that would be received by a person present at that locatio These calculations serve as the technical basis for theguidance provided in this sectio The details of this study were presented in Health Physics Journal, Volume 89, Number 3, 200 Based on these calculations, NRC will consider it acceptable to use the reading of a calibratedand correctly functioning survey meter, in R/hr, as directly indicating the effective dose rate to a visitor, in centisievert per hour (cSv/hr, rem/hr), who may be present at the survey locatio The surveys should be performed without the presence of the visitor, and the survey instrument should be held at some distance (e.g. at arm's length) from the body of the person performing the survey Failing to take these precautions will lead to high survey readings and will, in turn,cause the effective dose rate based on these readings to be overestimate This is a result of backscatter from the person's body contributing to the survey readin Assuming no internalexposures, the effective dose determined in this manner may be considered to be equal to the TEDE for purposes of showing compliance with applicable dose limits. It will be noted, on reviewing the Health Physics Journal article referred to above, that theresults indicated that the effective dose may be underestimated by as much as a factor of 2 under certain exposure conditions if the survey readings in R/hr are equated directly to the visitor dose in cSv/hr (rem/hr). The results also showed that the effective dose may be overestimated in some circumstance However, the calculations in the study were based on the assumption that the visitor was exposed while directly facing the patien Exposure in otherorientations, such as with one side or the back toward the patient, will result in significantlylower visitor doses for a given radiation fiel Therefore, if the reasonable assumption is made that visitors will generally be exposed from varying directions during their visits, using a one-to-one correspondence between the survey readings and the visitor doses is not likely to significantly underestimate or overestimate the visitor's dose, and is expected to yield estimates of the effective dose with an accuracy considered acceptable for this type of assessmen Attachment 2 Recently Issued NMSS Generic CommunicationsDateGC No.Subject

Addressees

2/11/05BL-05-01Material Control and Accounting atReactors and Wet Spent FuelStorage FacilitiesAll holders of operating licenses fornuclear power reactors, decommissioningnuclear powerreactor sites storing spent fuel in a pool,and wet spent fuel storage sites.10/28/05RIS-05-22Requirements for the PhysicalProtection During Transportation ofSpecial Nuclear Material ofModerate and Low StrategicSignificance: 10 CFR Part 72 vs.Regulatory Guide 5.59 (1983)All holders of licenses for the possessionof special nuclear material (SNM) thatship Category II and III quantities of thismaterial.9/27/05RIS-04-17,Rev. 1Revised Decay-in-StorageProvisions for the Storage ofRadioactive Waste ContainingByproduct MaterialAll licensees regulated under 10 CFRParts 30, 32, 33, 35, 39, and 50.8/25/05RIS-05-18Guidance for Establishing andMaintaining a Safety ConsciousWork EnvironmentAll licensees, applicants for licenses,holders of certificates of compliance, andtheir contractors subject to NRC authority8/10/05RIS-05-16Issuance of NRC ManagementDirective 8.17, "LicenseeComplaints Against NRCEmployees"All licensees and certificate holders.8/3/05RIS-05-15Reporting Requirements forDamaged Industrial RadiographicEquipmentAll material licensees possessingindustrial radiographic equipment,regulated under 10 CFR Part 34.7/13/05RIS-05-13NRC Incident Response and theNational Response PlanAll licensees and certificate holders.7/11/05RIS-05-12Transportation of RadioactiveMaterial Quantities of ConcernNRC Threat Advisory andProtective Measures SystemLicensees authorized to possessradioactive material that equals orexceeds the threshold values in theAdditional Security Measures (ASM) fortransportation of Radioactive MaterialQuantities of Concern (RAMQC) undertheir 10 CFR Part 30, 32, 50, 70, and 71licenses and Agreement State licenseessimilarly authorized to possess suchmaterial in such quantities under theirAgreement State licenses.7/11/05RIS-05-11Requirements for Power ReactorLicensees in Possession ofDevices Subject to the GeneralLicense Requirements of 10 CFR31.5All holders of operating licenses fornuclear power reactors and generallylicensed devicevendor Attachment 2 DateGC No.Subject

Addressees

6/10/05 RIS-05-10 Performance-Based Approach forAssociated Equipment in 10 CFR34.20All industrial radiography licensees andmanufacturers and distributors ofindustrial radiography equipment.4/18/05RIS-05-06Reporting Requirements forGauges Damaged at TemporaryJob SitesAll material licensees possessingportable gauges, regulated under 10 CFRPart 30.4/14/05RIS-05-04Guidance on the Protection ofUnattended Openings thatIntersect a Security Boundary orAreaAll holders of operating licenses orconstruction permits for nuclear powerreactors,research and test reactors,decommissioning reactors with fuel onsite, Category 1 fuel cyclefacilities, critical mass facilities, uraniumconversion facility, independent spentfuel storageinstallations, gaseous diffusion plants,and certain other material licensees.2/28/05RIS-05-0310 CFR Part 40 Exemptions forUranium Contained in AircraftCounterweights - Storage andRepairAll persons possessing aircraftcounterweights containing uranium underthe exemption in10 CFR 40.13(c)(5).10/31/05IN-05-28Inadequate Test Procedure Failsto Detect Inoperable CriticalityAccident Alarm HornsAll licensees authorized to possess acritical mass of special nuclear material.10/07/05IN-05-27Low Dose-Rate ManualBrachytheraphy EquipmentRelated Medical EventsAll medical licensees.7/29/05IN-05-22Inadequate Criticality SafetyAnalysis of Ventilation Systems atFuel Cycle FacilitiesAll licensees authorized to possess acritical mass of special nuclear material.6/23/05IN-05-17Manual Brachytherapy SourceJammingAll medical licensees authorized topossess a Mick applicator.5/17/05IN-05-13Potential Non-conservative Error inModeling Geometric Regions intheKeno-v.a Criticality CodeAll licensees using the Keno-V.a criticalitycode module in Standardized ComputerAnalyses for Licensing Evaluation(SCALE) software developed by OakRidge National Laboratory (ORNL)5/17/05IN-05-12Excessively Large Criticality SafetyLimits Fail to Provide DoubleContingency at Fuel Cycle FacilityAll licensees authorized to possess acritical mass of special nuclear material.4/7/05IN-05-10Changes to 10 CFR Part 71PackagesAll 10 CFR Part 71 licensees andcertificate holder Attachment 2 DateGC No.Subject

Addressees

4/1/05IN-05-07Results of HEMYC ElectricalRaceway Fire Barrier System FullScale Fire TestingAll holders of operating licenses fornuclear power reactors, except those whohavepermanently ceased operations and havecertified that fuel has been permanentlyremovedfrom the reactor vessel, and fuel facilitieslicensees.3/10/05IN-05-05Improving Material Control andAccountability Interface withCriticality Safety Activities at FuelCycle FacilitiesAll licensees authorized to possess acritical mass of special nuclear material.Note: NRC generic communications may be found on the NRC public website athttp://www.nrc.gov, under Electronic Reading Room/Document Collections.