ML20137Z361
| ML20137Z361 | |
| Person / Time | |
|---|---|
| Issue date: | 04/30/1997 |
| From: | NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | |
| References | |
| TASK-*****, TASK-RE REGGD-08.039, REGGD-8.039, NUDOCS 9704240107 | |
| Download: ML20137Z361 (20) | |
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{{#Wiki_filter:U.S. NUCLEAR REGULATORY COMMISSION April 1997 n nog \ Ui i REGULATORY GU DE
%**O *** / OFFICE OF NUCLEAR REGULATORY RESEARCH REGULATORY GUIDE 8.39 (Draft was DG-8015)
RELEASE OF PATIENTS ADMINISTERED RADIOACTIVE MATERIALS A. INTRODUCTION release, if the total effective dose equivalent is calcu-lated by (1) using the retained activity rather than the Section 35.75," Release ofIndividuals Containing activity administered, (2) using an occupancy factor Radiopharmaceuticals or Permanent implants," in less than 0.25 at 1 meter,(3) using the biological or ef-10 CFR Part 35," Medical Use of Byproduct Material,"
' fective half-life, or (4) considering the shielding by permits licensees to" authorize the release from its con-tissue."
trol of any individual who has been administered radio-pharmaceuticals or permanent implants containing ra. In 10 CFR 35.75(d), the licensee is required to dioactive material if the total effective dose equivalent " maintain a record, for 3 years after the date of release, to any other individual from exposure to the released in. that instructions were provided to a breast-feeding dividual is not likely to exceed 5 millisieverts (0.5 woman if the radiation dose to the infant or child from rem)." continued breast feeding could result in a total effective A Further,10 CFR 35.75(b) requires that the b.censee dose equivalent exceeding 5 millisieverts (0.5 rem)."
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() " provide the released individual with instructions, in- In this guide, the individual to whom the radioac-cluding written instructions, on actions recommended tive material has been administered is called the to maintain doses to other individuals as low as is rea- " patient." sonably achievable if the total effective dose equivalent This guide provides guidance to the licensee on to any other individual is likely to exceed 1 millisievert determining (1) when the licensee may authorize the (0.1 rem). If the dose to a breast-feeding infant or child release of a patient who has been administered radio-could exceed 1 millisievert (0.1 rem) assuming there ' pharmaceuticals or permanent implants containing ra-were no interruption of breast-feeding, the instructions dioactive material, (2) when instructions to the patient shall also include (1) guidance on the interruption or are required by 10 CFR 35.75(b), and (3) when records discontinuation of breast-feeding and (2)information are required by 10 CFR 35.75(c) and (d) to be generated on the consequences of failure to follow the guidance." and maintained. The guide lists activities for common-
'In addition,10 CFR 35.75(c) requires that the li- ly used radionuclides and their corresponding dose censee " maintain a record of the basis for authorizing rates with which a patient may be released in com-ti le release of an individual, for 3 years after the date of pliance with the dose limits in 10 CFR 35.75.
USNRC REGULA TORY GUIDES The guides se saved m the following ten broad divisens l Roguetary Gudes are esund to desenbe and make avalable to the pubke sucn informa-ton as metnods acceptable to the NRC staff for rnplementing specac pets of the Coris. p
- 1. Power Reactors 6 Products ' ,
trusamn s regulabons, tectvwques used by the staff m evaluahng speMc problems or pos' 2 Recoerch and Test Reactors 7 Traisportabon tulated acodonts. and data riesdod by the NRC staff n its renew of appiscatone for pe'- O i 3 Fuels and Matenals Facsimos 8 Occupatonal Health '
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\I issued guides may also be purchased from Ino Natonal Techrucal Informacon Service on Wntion comments may be submrtted to the Rules Remew and DwecDves Branch DFIPS, a standing order bass Detals on trws senrice may be obtened by wrmng NTIS. 5265 Port ADM. U S Nuclear Reguatory Commeson. Westungton, DC20555-0Wt. Royaf Road, Spnngftead, VA 22t61.
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l The information collections contained in this regu- clear medicine and brachytherapy procedures latory guide are covered by the requirements in 10 CFR are given in Appendix A to this guide, Part 35, which were approved by the Office of Manage-
- Default activities at which patients may be ment and Budget, approval number 3150-0010. The NRC may not conduct or sponsor, and a person is not released are calculated using the physical half-required to respond to, a collection ofinformation un- lives of the radionuclides and do not account i less it displays a currently valid OMB control number, for the biological half-lives of the !
radionuclides. B. DISCUSSION
- When release is based on biological elimina-tion (i.e., the effective half-life) rather thanjust The activities at which patients could be released the physical half-life of the radionuclide, b were calculated by using, as a starting point, the method Equation 1 is modified ta account for the up-discussed in the National Council on Radiation Protec- take and retention of the radionuclide by the tion and Measurements (NCRP) Report No. 37, " Pre- patient as discussed in Appendix B.
cautions in the Management of Patients Who Have
- For radionuclides with a physical half-life Received Therapeutic Amounts of Radionuclides" (Ref.1). greater than 1 day and no consideration of bio-logical elimination, it is assumed that the indi-NCRP Report No. 37 uses the following equation vidual likely to receive the highest dose from to calculate the exposure until time t at a distance r from exposure to the patient would receive a dose of the patient:
25 percent of the dose to total decay (0.25 in Equation 2) at a distance of 1 meter. Selection 34.6 r Oo T,(1 - c-0Nr) . of 25 percent of the dose to total decay at 1 me-D(t) = (Equation 1) r2 h hhhWmm ' surements discussed in the supporting regula-Where D(t) = Accumulated exposure at time t, in tory analysis (Ref. 2) that indicate the dose roentgens, calculated using an occupancy factor, E, of 25 34.6 = Conversion factor of 24 hrs / day percent at 1 meter is conservative in most nor-times the total integration of decay mal situations. (1.44),
- For radionuclides with a physical half-life less
, T = Specific gamma ray constant for a than or equal to 1 day, it is difficult tojustify an point source, R/ mci-hr at 1 cm, occupancy factor of 0.25 because relatively long-term averaging of behavior cannot be as-00 = Initial activity of the point source in sumed. Under this situation, occupancy fac-millicuries, at the time of the release, tors from 0.75 to 1.0 may be more appropriate. Tp = Physical half life in days, Thus, for radionuclides with a physical half-life r = Distance from the point source to the greater than 1 day: point ofinterest in centimeters, t
= Exposure time in days. p(m) = 34.6 r Oo T,(0.25) (Equation 2) 100 cm2 This guide uses the NCRP equation (Equation 1)in the following manner to calculate the activities at For radionuclides with a physical half-life less thhn I which patients may be released. r equa t 1 yn an ecup n y a r .
0 is used:
- The dose to an individual likely to receive the >
highest dose from exposure to the patient is
, 34.6 F Oo T, (1) (Equation 3) taken to be the dose to total decay. Therefore, 100 cm2 (1--e-0.693t/Tp) is set equal to 1.
e It is assumed that I roentgen is equal to 10 mil-Equations 2 and 3 calculate the dose from external hsteverts (1 rem). exposure to gamma radiation. These equations do not - include the dose from internal intake by household
- The exposure rate constants and physical half- members and members of the public because the dose lives for radionuclides typically used in nu- from intake by other individuals is expected to be small 8.39 - 2
____ _ d
for most radiopharmaceuticals (less than a few percent) If a radionuclice not listed in Table 1 is adminis-relative to the external gamma dose (see Section B.3, tered, the licensee can demonstrate compliance with the Internal Dose," of Appendix B). Further, the equations regulation by maintaining, for NRC inspection, a cal-culation of the release activity that corresponds to the O "above do not apply to the dose to breast-feeding infants dose limit of 5 millisieverts (0.5 rem). Equation 2 or 3 or children who continue to breast-feed. Patients who are breast-feeding an infant or child must be considered may be used, as appropriate, to calculate the activity Q separately, as discussed in Regulatory Position 1.1, corresponding to 5 millisieverts (0.5 rem).
" Release of Patients Based on Administered Activity." The release activities in Column l of Table 1 do not include consideration of the dose to a breast-feeding in-C. REGULATORY POSITION fant or child from ingestion of radiopharmaceuticals contained in a patient's breast milk. When the patient is breast-feeding an infant or child, the activities in Col-
- 1. RELEASE CRITERIA
*"" I * .are n t appHeaWe to We yant or Licensees should use one of the following options ,
child. In this case, it may be necessary to give mstruc-to release a patient who has been administered radio- ti ns as described in Regulatory Positions 2.2 and 2.3 pharmaceuticals or permanent implants containing as a c ndition for release if failure tointerrupt or dis-radioactive material in accordance with regulatory continue could result m a dose to the breast-feeding in-requ ements. fant or child in excess of 5 millisieverts (0.5 rem), a re-c rd that instructions were provided is required by 10 1.1 Release of Patients Based on Administered CFR 35.75(d). Activity In compliance with the dose limit in 10 CFR 1.2 Release of Patients Based on Measured Dose 35.75(a), licensees may release patients from licensee Rate controlif the activity administered is no greater than the Licensees may release patients to whom radionu-activity in Column 1 of Table 1. The activities in clides have been administered in amounts greater than Table 1 are based on a total effective dose equivalent of the activities listed in Column 1 of Table 1 provided the O 5 millisieverts (0.5 rem) to an individual using conser-vative assumptions of (1) administered activity, measured dose rate at 1 meter (from the surface of the patient) is no greater than the value in Column 2 of Table 1 for that radionuclide. In this case, however,10 (2) physical half-life, (3) occupancy factor of 0.25 at 1 meter for physical half-lives greater than 1 day, and, for CFR 35.75(c) requires a record because the release is conservatism, an occupancy factor of 1 at 1 meter for based on considering shielding by tissue. physical half-lives less than or equal to 1 day, and (4) no . if a radionuclide not listed in Table 1 is adm. .ims-shielding by tissue. The total effective dose equivalent tered and the licensee chooses to release a patient based is approximately equal to external dose because the in- n the measured dose rate, the licensee should first cal-ternal dose is a small fraction of the external dose (see wlate a dose rate that corresponds to the 5-milhsievert Section B.3, " Internal Dose," of Appendix B). In this case, no record of the release of the patient is required (0.5-rem) dose limit. If the measured dose rate at 1 me-ter is no greater than the calculated dose rate, the patient unless the patient is breast-feeding an infant or child as may be released. A record of the release is required by discussed in Regulatory Position 3.2," Records of in- 10 CFR 35.75(c). The dose rate at 1 meter may be cal-structions for Breast-Feeding Patients." The licensee mlated from Equation 2 or 3, as appropriate, because may demonstrate compliance by using the records of the dose rate at 1 meter is equal to 1 O/10,000 cm2 , activity that are already required by 10 CFR 35.32 and 35.53. 1.3 Release of Patients Based on Patient Specific Dose Calculations If the activity administered exceeds the activity in Column 1 of Table 1, the licensee may release the pa- Licensees may release patients based on dose cal-tient when the activity has decayed to the activity in culations using patient-specific parameters. With this Column 1 of Table 1. In this case, a record is required by method, based on 10 CFR 35.75(a), the licensee must 10 CFR 35.75(c) because the patient's release is based calculate the maximum likely cose to an individual ex-posed to the patient on a case-by-case basis. If the cal-j O on the retained activity rather than the administered ac-tivity The activities in Column 1 of Table 1 were calcu-lated using either Equation 2 or 3, depending on the culated maximum likely dose to an individual is no greater than 5 millisieverts (0.5 rem), the patient may physical half-life of the radionuclide. be released. Using this method, licensees may be able 8.39 -3
Table 1. Activities cnd Dose Rates for Authorizing Ittient R:le: set COLUMN 1 COLUMN 2 Activity at or Dose Rate at 1 Meter, at or Below Which Patients May Be Below Which Patients May Be l Released Released
- Radionuclide (GBq) (mci) (mSv/hr) (mrem /hr)
Ag-111 19 520 0.08 8 l Au-198 3.5 93 0.21 21 Cr-51 4.8 130 0.02 2 Cu-64 8.4 230 0.27 27 Cu-67 14 390 0.22 22 Ga-67 8.7 240 0.18 18 l-123 6.0 160 0.26 26 I-125 0.25 7 0.01 1 1-125 implant 0.33 9 0.01 1 1-131 1.2 33 0.07 7 In-111 2.4 64 0.2 20 Ir-192 implant 0.074 2 0.008 0.8 P-32 " " " " Pd-103 implant 1.5 40 0.03 3 Re-186 28 770 0.15 15 Re-188 29 790 0.20 20 Sc-47 11 310 0.17 17 Se-75 0.089 2 0.005 0.5 Sm-153 26 700 0.3 30 Sn-117m 1.1 29 0.04 4 Sr-89 ** ** ** ** Tc-99m 28 760 0.58 58 TI-201 16 430 0.19 19 Y-90 ** ** ** ** Yb-169 0.37 10 0.02 2 t The activity values were computed based on 5 millisieverts (0.5 rem) total effective dose equivalent. *
- If the release is based on the dose rate at I meter in Column 2, the licensee must maintain a record as required by 10 CFR 35.75(c) because the measurement includes shielding by tissue. See Regulatory Position 3.1," Records of Release /' for information on records.
r*
- Activity and dose rate limits are not applicable in this case because of the minimal exposures to members of the public esulting from activities normally administered for diagnostic or therapeutic purposes.
NOTES: The millicurie values were calculated using Equations 2 or 3 and the physical half. life. The gigabecqueret values vwere calculated based on the millicurie values and the conversion factor from millicuries to gigabecquerels. The dose rate alues are calculated based on the millicurie values and the exposure rate constants. I on general, the values are rounded to two significant figures. liowever, values less than 0.37gigabecquerel (10 millicunes) NrUREG-!492 0.1 millisievert (10 millirems) per hour are rounded to ors (tnificant figure. Details of the calculations are provided in (Ref. 2). A lthough non-byproduct materials are not regulated by the NRC, information on non.bypoduct material is included in this r egulatory guide for the convenience of the licensee. A greement t hese values. State regulations may vary. Agreement State licensees should check with their State regulations prior to using l 8.39-4
to release patients with activities greater than those breast-feeding status of the patient.1 The purpose of the listed in Column 1 of Table 1 by taking into account the instructions (e.g., on interruption or discontinuation) is b effective half-life of the radioactive material and other to permit licensees to release a patient who could be factors that may be relevant to the particular case. If the breast-feeding an infant or child when the dose to the dose calculation considered retained activity, an occu- infant or child could exceed 5 millisieverts (0.5 rem) if pancy factor less than 0.25 at 1 meter, effective half- there is no interruption of breast-feeding. life, or shielding by tissue, a record of the basis for the if the patient could be breast-feeding an infant or release is required by 10 CFR 35.75(c). child after release, and if the patient was administered a Appendix B contains procedures for performing radiopharmaceutical with an activity above the value stated in Column.1 of Table 3, instructions on disconti-patient specific dose calculations, and it describes how various factors may be considered in the calculations, nuation or on the interruption period for breast-feeding and time consequences of failing to follow the recom-
- 2. INSTRUCTIONS mendation must be provided. The patient should also be informed if there would be no consequences to the 2.1 Activities and Dose Rates Requiring breast-feeding infant or child. Table 3 also provides rec-Instructions ommendations for interrupting or discontinuing breast-Based on 10 CFR 35.75(b), for some admimstra- feeding to minimize the dose to below 1 millisievert tions the released patients must be given instructions' , (0.1 rem) if the patient has received certain radiophar-includmg written mstructions, on how to maintain ,
maceutical doses. The radiopharmaceuticals listed in doses to other ,mdividuals as low as is reasonably Table 3 are commonly used in medical diagnosis and achievable after the patients are released.1 Licensees treatment
- may use Column 1 of Table 2 to determine the activity above which instructions must be given to patients. if a radiopharmaceutical not listed in Table 3 is administered to a patient who could be breast-feeding, Column 2 provides corresponding dose rates at 1 meter, based on the activities in Column 1. If the patient is the licensee should evaluate whether instructions or re-cords (or both) are required. If information on the ex-O breast-feeding an infant or child, additional instruc-cretion of the radiopharmaceutical is not available, an Q tions may be necessary (see Regulatory Position 2.2,
" Additional Instructions for Release of Patients Who acceptable method is to assume that 50 percent of the Could be Breast-Feeding After Release"), administered activity is excreted in the breast milk
. (Ref. 2). The dose to the infant or child can be calcu-The activities or dose rates m. Table 2 may be used using the dose conversion factors given for a I
for determining when instructions must be given. , newborn mfant by Stabin (Ref. 3). When patient-specific calculations (as described in Ap-pendix B) are used, instructions must be provided if the 2.3 Content ofInstructions calculation indicates a dose that is greater than 1 milli- The instructions should be specific to the type of sievert (0.1 rem). treatment given, such as permanent implants or rad.io-If a nadionuclide not listed in Table 2 is adminis- iodine for hyperthyroidism or thyroid carcinoma, and tered, the licensee may calculate the activity or dose they may include additional information for individual rate that corresponds to 1 millisievert (0.1 rem). Equa- situations. However, the instructions should not inter-tion 2 or 3, as appropriate, may be used. fere with or contradict the best medical judgment of physicians. The instructions may include the name of a 2'.2 Additional Instructions for Release of Patients knowledgeable person to contact and that person's tele-Who Could be Breast Feeding After Release phone number in case the patient has any questions. The requirement in 10 CFR 35.75(b) that a licensee Additionalinstructions appropriate for each modality, provide instructions on the discontinuation or the inter- as shown in examples below, may be provided. ruption period of breast-feeding, and the consequences of failing to follow the recommendation, presumes that 2.3.1 Instructions Regarding the licensee will inquire, as appropriate, regarding the Radiophr maceutical Administrations S E "" p IThe NRC does not intend to enforce patient cornpliance with the instruc-tions noris it the licensee's responsibihty to do so. E additional instructions may include the following. 839-5 [
Table 2.Authorizing Activities Patient and Dose Rates Above Which Instructions Should be Given When Release
- COLUMN 1 COLUMN 2 Activity Above Which Instrue.
Dose Rate at 1 Meter Above tions Are Required Which Instructions Are Required Radionuclide (Gilq) (MCI) (mSv/hr) (mrem /hr) Ag-111 3.8 100 0.02 2 Au-198 0.69 19 0.04 4 Cr-51 0.96 26 0.004 0.4 Cu-64 1.7 45 0.05 5 Cu-67 2.9 77 0.04 4 Ga-67 1.7 47 0.04 4 I-123 1.2 33 0.05 5 , 1-J25 0.05 1 0.002 0.2 1-125 implant 0.074 2 0.002 0.2 I-131 0.24 7 0.02 2 In-111 0.47 13 0.04 4 Ir-192 implant 0.011 0.3 0.002 0.2 P-32 ** ** ** ** Pd-103 implant 0.3 8 0.007 0.7 Re-186 5.7 150 0.03 3 Re-188 5.8 160 0.04 4 Sc-47 2.3 62 0.03 3 Se-75 0.018 0.5 'J.001 0.1 Sm-153 5.2 140 0.06 6 Sn-117m 0.21 6 0.009 0.9 g._gg .. .. n .. Tc-99m 5.6 150 0.12 12 TI-201 3.1 85 0.04 4 Y-90 " " " " Yb-169 0.073 2 0.004 0.4 .
- The activity values were computed based on 1 millisievert (0.1 rem) total effective dose equivalent.
r" Activity and dose rate limits are not applicable in this case because of the minimal exposures to members of the public esulting from activities normally administered for diagnostic or therapeutic purposes. NOTES: w The millicurie values were calculated using Equations 2 or 3 and the physical half-life. The gigsbecquerel values u ere calculated based on millicuric values and the conversion factor from millicuries togigabecquerels. The dose rate val-cs were calculated based on millicurie values and exposure rate constants. I 0 n general, values are rounded to two significant figures. Ilowever, values less than 0.37 gigabecquerel (10 millicuries) or 1 millisievert (10 millirems) per hour are rounded to one significant figure. Details of the calculations are provided in N UREG-1492 (Ref. 2). A lthough non-byproduct materials are not regulated by the NRC, information on non-byproduct material is included in this r egulatory g,uide for the consenience of the licensee. A greement these values. State regulations may vary. Agreement State licensees should check with their State regulations prior to using O l 8.39-6
Table 3. Acthities of Radiopharmaceuticals that Require Instructions and Records When Administered to Patiene Who Are Breast Feeding an Infant or Child 7 s COLUMN 2 COLUMN 3 COLUMN 1 ( l Activity Above Which a Examples of
'~ Activity Above Which Instructions Are Required Record Is Required Recommended Duration ofInterruption of Radiopharmaceutical (Milq) (mci) lireast Feeding *
(MBq) (mCl) 0 0004 0.07 0.002 Complete cessation (for I-131 Nal 0.01 this infant or child) 20 0.5 100 3 1-123 Na1 100 4 700 20 1-123 Olii 400 10 24 hr for 370 MBq 70 2 1-123 mIBG (10 mci) 12 hr for 150 MBq (4 mci) 0.08 10 0.4 I-125 Olli 3 10 0.30 60 1.5 1-131 Olli 1,000 30 6,000 150 Tc-99m DTPA 1.3 200 6.5 12.6 hr for 150 MBq Tc-99m MAA 50 (4 mci) 3 600 15 24 hr for 1,100 MBq Tc-99m Pertechnetate 100 (30 mci) 12 hr for 440 MBq (12 mci) 1,000 30 6.000 150
) Tc-99m DISIDA Tc-99m Glucoheptonate 1,000 30 6,000 170 Tc-99m HAM 400 10 2,000 50 Tc-99m MIBl 1,000 30 6,000 150 Tc-99m MDP 1,000 30 6,000 150 Tc-99m PYP 900 25 4,000 120 400 10 2,000 50 6 hr for 740 MBq Tc-99m Red Blood Cell In Vivo Labeling (20 mci)
Tc-99m Red Blood Cell in 1,000 30 6,000 150 Vitro Labeling Tc-99m Sulphur Colloid 300 7 1,000 35 6 hr for 440 MBq (12 mci) Tc-99m DTPA Aerosol 1,000 30 6/K)0 150 Tc-99m MAG 3 1,000 30 6,000 150 Tc-99m White Blood 100 4 600 15 24 hr for 1,100 MBq Cells (5 mci) 12 hr for 440 MBq (2 mci) 7
,Y 8.39 - 7
Table 3. (continued) COLUMN 1 COLUMN 2 COLUMN 3 Activity Above Which Activity Above WMeh a Instructions Are Required Examples of Radiopharmaceutical Record is Required Recommended Duration (MBq) (mci) (MBq) ofInterruption of (mci) Ga-67 Citrate Breast-Feeding
- 1 0.04 7 0.2 1 month for 150 MBq (4 mci) 2 weeks for 50 MBq (1.3 mci)
I week for 7 MBq Cr-51 EDTA (0.2 mci) 60 1.6 300 8 In-111 White Blood Cells 10 0.2 40 1 1 week for 20 MBq TI-201 Chloride 40 (0.5 mci) 1 200 5 2 weeks for 110 MBq (3 mci) the regulatory limit is 5 millisieverts (0.5 rem). The actual n millisievertdoses that would be recei (O.I rem). although course, the physician may use discretion in the recommendation, increasing or decreasing the duration of interruptio tions are shown in NUREG-1492," Regulatory Analysis on I Criteria gures. for the Release of Details of the calcula-i f there is no recommendation in Column 3 of this table, the maximum activity normally administered is below the nterruption or discontinuation of breast-feeding. v es that require instructions on Ahhough nience non-byproduct of the licensee. materials are not regulated by the NRC, informationison non-byproduct material is included in t regulatory guide for the conve-Agreement State regulations may vary. Agreement State licensees should o o using check with their state regulations pn r t these values. O e Maintaining distance from other persons, structions in this pamphlet te be an acceptable method including separate sleeping arrangements. f r meeting the requirements of 10 CFR 35.75(b) pro-
- vided the times filled in the blanks are appropriate for Minimizing time in public places (e.g.,
public transportation, grocery stores, the activity and the medical condition. shopping centers, theaters, restaurants, If additionalinstructions are required because the sporting events). patient is breast feeding, the instructions should in-Precautions to reduce the spread of radio- clude appropriate recommendations on whether to in-active contammation. terrupt breast-feeding, the length of time to interrupt The length of time each of the precautions breast-feeding, or, if necessary, the discontinuation of should be in effect. F a.st-feeding. The instructions should include infor-mation on the consequences of failure to follow the rec-ommendation to interrupt or discontinue breast-The Society of Nuclear Medicine published a pam-phlet in 1987 that provides information for patients re- feeding. The consequences should be explained so that a the patient will understand that, in some cases, breast-ceiving treatment with radiciodine (Ref. 4). This pam-phlet was prepared jointly by the Society of Nuclear feeding after an administration of certain radionuclides Medicine and the NRC. The pamphlet contains blanks should be avoided. For example, a consequence of pro-for the physician to fill in the length of time that each cedures involving iodine-131 is that continued breast-instruction should be followed. While this pamphlet feeding could harm the infant's or child's thyroid. Most was written for the release of patients to whom less than diagnostic procedures involve radionuclides other than 1,110 megabecquerels (30 millicuries) of iodine-131 radiciodine and there would be no consequences; had been administered, the NRC still considers the in- guidance should simply address avoiding any unneces-sary radiation exposure to the infant or child from 8.39-8
breast-feeding. If the Society of Nuclear Medicine's 3. RECORDS pamphlet is given at release to a patient who is breast-3.1 Records of Release p feeding an infant or child, the pamphlet should be sup-plemented with information specified in 10 CFR There is no requirement for recordkeeping on the 35.75(b)(1) and (2). release of patients who were released in accordance with Column 1 of Table 1. Ilowever,if the release of the The requirement of 10 CFR 35.75(b) regarding patient is based on a dose calculation that considered re-written instructions to patients who could be breast-tained activity, an occupancy factor less than 0.25 at 1 feeding an infant or child does not in any way interfere meter, effective half-life, or shielding by tissue, a rec-with the discretion and judgment of the physician in ord of the basis for the release is required by 10 CFR specifying the detailed instructions and recommenda-35.75(c). This reccia should include the patient identi-tions. fier (in a way that ensures that confidential patient in- r formation is not traceable or attributable to a specific 2.3.2 Instructions Regarding Permanent Implants patient), the radioactive material administered, the For patients who have received permanent im. administered activity, and the date of the administra- , plants, additional instructions may include the follow. tion. In addition, depending on the basis for release, ing records should include the following information. A small radioactive source has been (1) ForImmediate Release of a Patient Based on placed (implanted) inside your body. The a Patient Specific Calculation: The equation used, source is actually many small metallic pellets including the patient-specific factors and their bases or seeds, which are each about 1/3 to 1/4 of an that were used in calculating the dose to the person ex-inch long, similar in size and shape to a grain of Posed to the patient, and the calculated dose. The rice. To minimize exposure to radiation to oth- patient-specific factors (see Appendix B of this guide) ers from the source inside your body, you include the effective half-life and uptake fraction for should do the following for each component of the biokinetic model, the time that days. p the physical half-life was assumed to apply to retention, (
- Stay at a distance of feet from and the occupancy factor. The basis for selecting each of these values should be included in the record. !
(2) ForImmediate Release of a Patient Based on '
- Maintain separate sleeping arrangements. hicasured Dose Rate: The results of the measurement,
- Minimize time with children and pregnant the specific survey instrument used, and the name of the i women. individual performing the survey. 1 (3) For Delayed Release of a Patient Based on
- Do not hold or cuddle children.
Radioactive Decay Calculation: The time of the ad-
- Avoid public transportation. ministration, date and time of release, and the results of the decay calculation.
- Examine any bandages orlinens that come into contact with the implant site for any (4) For Delayed Release of a Patient Based on pellets or seeds that may have come out of hieasured Dose Rate: The results of the survey meter the implant site, measurement, the specific survey instrument used, and the name of the individual performing the survey.
- If you find a seed or pellet that falls out:
In some s.tuations, i a calculat. ion may be case-
- Do not handle it with your fingers, specific for a class of patients who all have the same Use something like a spoon or tweez- patient-specific factors. In this case, the record for a ers to place it in a jar or other container particular patient's release may reference the calcula- l that you can close with a lid. tion for the class of patients.
- Place the container with the seed or Records, as required by 10 CFR 35.75(c), should
, pellet in a location away from people. be kept in a manner that ensures the patient's confiden-y liality, that is, the records should not contain the pa-
- Notify one of the persons listed in this tient's name or any other information that could lead to instruction. identification of the patient. These recordkeeping re-8.39-9 1
i
quirements may also be u. sed to verify that licensees tered activity, the date of the administration, and wheth-have proper procedures in place for assessing potential er instructions were provided to the patient who could third-party exposure associated with and arising from be breast-feeding an infant or child. 1 exposure to patients administered radioactive naterial.
- 4. Summary Table 3.2 Records ofInstructions for Breast Feed:ng Patients Table 4 summarizes the criteria for releasing pa-tients and the requirements for providing instructions if failure to interrupt or discontinue breast-feeding and maintaining records.
could result in a dose to the infant or child in excess of 5 millisieverts (0.5 rem), a record that instructions were D. IMPLEMENTATION provided is required by 10 CFR 35.75(d). Column 2 of l Table 3 states, for the radiopharmaceuticals commonly The purpose of this section is to provide informa-used in medical diagnosis and treatment, the activities tion to licensees and applicants regarding the NRC { that would require such records when administered to staff's plans for using this regulatory guide. patients who are breast-feeding. Except in those cases in which a licensee proposes The record should include the patient's identifier an acceptable alternative method for complying with (in a way that ensures that confidential patient informa- 10 CFR 35.75, the methods described in this guide will tion is not traceable or attributable to a specific patient), be used in the evaluation of a licensee's compliance the radiopharmaceutical administered, the adminis- with 10 CFR 35.75. O 1 ( l l O 8.39 - 10
v ' Table 4. Summary of Release Criteria, Required Instructions to Patients, and Records To Be Maintained PATIENT GROUP HASIS FOR RELEASE CRITERIA FOR RELEASE INSTRUCTIONS NEEDED? RELEASE RECORDS REQUIRED? All patients, Administered activity Administered activity Yes-if administered activity No including patients s Column 1 of Table 1 > Column 1 of Table 2 who are breast- Yes-if retained activity Yes Retained activity Retained activity r. Column 1 feeding an infant or > Column 1 of Table 2 f Table 1 child Measured dose rate Measured dose rate s Column Yes -if dose rate > Column 2 Yes
,2 of Table 1 of Table 2 Patient-specific Calculated dose s 5 mSv (0.5 Yes -if calculated dose > 1 Yes calculations rem) mSv (0.1 rem)
Patients who are All the above bases for Additional instructions Records that instructions were j breast-feeding an release required if: provided are required if: infant or child Administered activity Administered activity
> Column 1 of Table 3 > Column 2 of Table 3 C or or Licensee calculated dose fmm Licensee calculated dose from breast-feeding > 1 mSv (0.1 continued breast-ft.eding > 5 mSv (0.5 rem) to the infant or child rem) to the infant or child
REFERENCES
- 1. National Council on Radiation Protection and Edited by S. Treves, Springer Verlag, New York, Measurements (NCRP), " Precautions in the Man- 1995.
agement of Patients Who llave Received Thera-peutic Amounts of Radionuclides," NCRP Report 4. " Guidelines for Patients Receiving Radiciodine No. 37, October 1,1970. (Available for sale from Treatment," Society of Nuclear Medicine,1987. the NCRP,7910 Woodmont Avenue, Suite 800, This pamphlet may be obtained from the Society Bethesda, MD 20814-3095.) of Nuclear Medicine,136 Madison Avenue, New York, NY 10016-6760.
- 2. S. Schneider and S. A. McGuire, " Regulatory Analysis on Criteria for the Release of Patients ' Copies may be purchased ai current rates from ihe u.s covernment Prini-Administered Radioactive Material," NUREG- ing office. P. O. Box 37082, Washington, DC 20402-9328 (telephone (202)512-2249; or from the National Technica. Information service by 1492 (Final Report), NRC, February 1997.. w niing NTis ai 5285 Port Royal Road. springfield, VA 22161. Copies are also available for inspection and copying for a fee from the NRC Public D '"**"t Room at 2120 L street NWDwer Level), Washington, DC. g
- 3. M. Stabin, " Internal Dosimetry in Pediatric Nu-The PDR.s mailing address is Mail stop LL-6, Washington, DC 20555; clear Medicine," in Pediatric Nuclear Medicine, telephone (202)634-3273; fax (202)634-3343.
O 8.39 - 12
APPENDIX A b Table A-1. Half Lives and Exposure Rate Constants of Radionuclides Used in Medicine Exposure Hate Exposure Rate Half. Life Constant 3 IIalf Life Comtant3 Radionuclidet (days)2 (R/ mci-h at I cm) Radionuclidel (days)2 (R/ mci-h at I cm) Ag-111 7.45 0.150 Pd-103 implant 16.96 0.865 Au-198 2.696 2.3 Re-186 3.777 0.2 Cr-51 27.704 0.16 Re-188 0.708 0.26 Cu-64 0.529 1.2 Sc-47 3351 0.56 Cu-67 2.578 0.58 Se-75 119.8 2.0 Ga-67 3.261 0.753 Sm-153 1.946 0.425 I-123 0.55 1.61 Sn-117m 13.61 l 1.48 I-125 60.14 1.42 Sr-89 50.5 NA6 I-125 implant 60.14 1.114 Tc-99m 0.251 0.756 I-131 8.04 2.2 TI-201 3.044 0.447 In-111 2.83 3.21 Y-90 2.67 NA6 ! Ir-192 implant 74.02 4.594 Yb-169 32.01 1.83 I P-32 14.29 NA6 l 1 Although non-byproduct snaterials are not regulated by the NRC, information on non-byproduct material is included in this regulatory guide for the convenience of the licensee. 2 K.F. Eckerman, A.B. Wolbarst, and A.C.B. Richardson," Federal Guidance Repon No. I1, Limiting Values of Radionuclide Int ke and Air Concentra. tion and Dose Conversion Factors for trialation, Submersion, and Ingestion," Report No. EPA-520/1-88-020, Office of Radiation Programs, U.S. Envi-
, ronmental Protection Agency, Washington, DC,1988. \ 3 Values for the exposure rate constant for Au-198, Cr-S t, Cu-64,1-131, Sc-47, and Se-75 w ere taken from the Radwlogicalllealth Handbook, U.S.
Department ofIlealth, Education, and Welfare, pg. 135,1970. For Cu-67,1-123, In-l i t , Re-186, and Re-188, the s alues for the e sposure rate constant were taken from D E. Barber, J.W. Haum, and C.B. Meinhold," Radiation Safety issues Related to Radiolabeled Antibodies," NUREG'CR-4444, U.S. N RC, Washington, DC,1991. Fot Ag-i l l, Ga-67,1-125, Sm-153, Sn-l l 7m,Tc-99m,Tl 201, and Yb-169. t he exposure rate constants w ere calculated because lhe published values for these radionuclides were an approximation, presented as a range, or varied from one reference to another. Details of the calculation of the exposure rate constants are shown in Table A 2 of Appendix A to NUREG-1492," Regulatory Analysis on Cnteria for the Release of Patients Administered Radioactive Material," U.S. NRC, February 1997. 4 R. Nath, A.S. Meigooni, and J.A. Meli," Dosimetry on Transverse Axes of125l and l'21r Interstitial Hrachytherapy Sources," Medical Physics, Volume 17, Number 6, November / December 1990. The exposure rate constant given is a measured value averaged for seseral source models and takes into ac-count the attenuation of gamma rays within the implant capsule itself. 5 A.S. Meigooni, S. Sabnis, R. Nath " Dosimetry of Palladium 103 Brachytherapy Sources for Permanent implants /' Endocurierherapy Hyperthermia Oncology, Wlume 6, April 1990.The exposure rate constant given is an" apparent"value (i.e., with respect to an apparent source activity)and takes into account the attenuation of gamma rays within the implant capsule itself. 6 Not applicable (NA) because the release activity is not based on beta emissions. i l C i l 8.39 -13 m
APPENDIX B PROCEDURES FOR CALCUIEFING DOSES BASED ON PATIENT-SPECIFIC FACTORS A licensee may release a patient who has been that measurements of doses to family members as well administered an activity higher than the values listed in as considerations of normal human behavior (as dis-Column 1 of Table 1 of this regulatory guide if dose cal- cussed in the supporting regulatory analysis (Ref. B-1)) suggest that an occupancy factor of 0.25 at 1 me- I culations using patient-specific parameters, which are I less conservative than the conservative assumptions, ter, when used in combination with the physical half-show that the potential total effective dose equivalent to life, will produce a generally conservative estimate of any individual would be no greater than 5 millisieverts the dose to family members when instructions on mini-mizing doses to others are given. (0.5 rem). 1 If the release of a patient is based on a patient. An occupancy factor of 0.25 at 1 meter is not con-specific calculation that considered retained activity, an sidered appropriate when the physical half-life is less occupancy factor less than 0.25 at 1 meter, effective than or equal to 1 day, and hence, the dose is delivered y half life, or shielding by tissue, a record of the basis of over a short time. Specifically, the assumptions regar-the release is required by 10 CFR 35.75(c). ding patient behavior that led to an occupancy factor of 0.25 at 1 meter include the assumption that the patient The following equation can be used to calculate will n t be in close proximity to other mdividuals for doses: several days. However, when the dose is from a short-lived radionuclide, the time that individuals spend in 34.6 F Oo TE (1 - e-"%) (Equation B-1) close proximity to the patient immed:ately following D(t) = g release will be most significant because the dose to oth-er individuals could be a large fraction of the total dose Where D(t) = Accumulated dose to time t,in rems from the short-lived radionuclide. Thus, to be conser-34.6 = Conversion factor of 24 hrs / day vative when providing generally applicable release times the totalintegration of decay quantities that may be used with little consideration of (1.44) the specific details of a particular patient's release, the values calculated in Table 1 were based on an occupan-F = Exposure rate constant for a point source, R/ mci x hr at 1 cm cy factor of 1 at 1 meter when the half life is less than or Y U Oo = Initial activity at the start of the time interval B.1.2 Occupancy Factors To Consider for Patient. Specific Calculations Tp = Physical half-life in days
**** n an ccupancy factor for patient-E = Occupancy factor that accounts for .
specific calculations will depend on whether the physi-different occupancy times and dis-tances when an individual is around C I ' *".ective half-life of the radionuclide is used and whether instructions are provided to the patient before release. The following occupancy factors, E, at 1 meter, r = Distance in centimeters. This value may be used for patient-specific calculations. is typically 100 cm
- E = 0.75 when a physical half-life, an effective 4
t = exposure time in days half-life, or a specific time period under consider-ation (e.g., bladder holding time) is less than or B.1 OCCUPANCY FACTOR equal to 1 day. B.1.1 Rationale for Occupancy Factors Used To e E = 0.25 when an effective half-life is greater than 1 Derive Table 1 day if the patient has been given instructions, such as, In Table 1 in Regulatory Guide 8.39, the activities at which patients could be released were calculated us-
- Maintain a prudent distance from others for at ingthe physical half-life of the radionuclide and an oc- least the first 2 days, cupancy factor at 1 meter of either 0.25 (if the radionu-
- Sleep alone in a room for at least the first night, clide has a half-life longer than 1 day) or 1.0 (if the radionuclide has a half-life less than or equal to 1 day).
- Do not travel by airplane or mass transporta-The basis for the occupancy factor of 0.25 at 1 meter is tion for at least the first day, 8.39 - 14
I l o Do not travel on a prolonged automobile trip Since the dose is less than 5 mi..isieverts (0.5 rem), with others for at least the first 2 days, the patient may be released, but 10 CFR 35.75(b) re-
/ \ quires that instructions be given to the patient on main-(") e llave sole use of a bathroom for at least the first 2 days, taining doses to others as low as is reasonably achiev-able. A record of the calculation must be maintained e Drink plenty of fluids for at least the first 2 pursuant to 10 CFR 35.75(c) hecause an occupancy fac-days. tor less than 0.25 at 1 meter was used.
e E = 0.125 when an effective half-life is greater than B.2 EFFECTIVE HALF LIFE 1 day if the patient has been given instructions, A licensee may take into account the effe.ctive half-such as, life of the radioactive material to demonstrate com-
- Follow the instructions for E = 0.25 above, pli oce with the dose limits for individuals exposed to the patient that are stated in 10 CFR 35.75. The effec-e Live alone for at least the first 2 days, tive half-life is defined as:
e llave few visits by family or friends for at least the first 2 days. T,, = { (Equation B-2)
- In a two-component model (e.g., uptake of iodine-131 using thyroidal and extrathyroidal Where Tb = biological half-life of the radionu-components), if the effective half-life associated clide with one component is less than or equal to one day TP = physical half-life of the radionu-but is greater than one day for the other component, it is rr. ore justifiable to use the occupancy factor as-sociated with the dominant component for both The behavior of iodine-131 can be modeled using components. two components: extrathyroidal iodide (i.e., existing n outsiie of the thyroid) and thyroidal iodide following Example 1: Calculate the maximunilikely dose t (V) an individual exposed to a patient who has received uptake by the thyroid. The effective half-lives for the extrathyroidal and thyroidal fractions (i.e., Fi and F2, 2,220 megabecquerels (60 millicuries) of iodine-131.
respectively) can be calculated with the following The patient has been provided with instructions t equations. maintain a prudent distance from ethers for at least 2 days, lives alone, drives home alone, and stays at home for several days without visitors. Ti ," ' T. x T' (Equation B-3) T +T Solution: The dose to total decay (t = z) is calcu-lated based on the physical half-life using Equation
- xT
.g.
B-1. (This calculation illustrates the use of physical P (equation B-4) half-life. To account for biological elimination, cal-T.s = T 62 +T 2 P culations described in the next section should be used.) Where Tb1 = biological half-life for extrathyroi-dal iodide D( x) = 34.6 l' Oo T, E 7 2 Tb2 = biole ;al half-life of iodide follow-ing uptake by the thyroid Since the patient has been provided with instruc- Tp = physical half-life of iodine-131. tions for reducing exposure as recommended for an oc* Ilowever, simple exponential excretion models do cupancy iactor of E = 0.125, the occupancy factor of not account for (a) the time for the iodine-131 to 1 e ab-0.125 at 1 meter may be used. sorbed from the stomach to the blood and (b) the i. 2 dup ofiodine in the urine while in the bladder. Failure to ac-m 34.6 (2 ' 2 cm / mci hr'(60 mci)(8.04 d)(0.125) count for these factors could result in an underestimate I i DI ~ of the dose to another individual. Therefore, this guide (too cm)2 U makes a conservative approximation to account for these factors by assuming that, during the first 8 hours D (x) = 4.59 millisieverts (0.c 59 tem) after the administration, about 80 percent of the 8.39 - 15 s
iodine-131 administered is removed from the body at a E2 = Occupancy factor from 8 hours to to-rate determined only by the physical half-life of tal decay.
" I' All the other parameters are as defined in Equa- I Thus, an equation to calculate the dose from a pa- tions B-1, B-3, and B-4. Acceptable values for F t, tient administered iodine-131 may have three compo- T ieff, F2, and T2err are shown in Table B-1 for thyroid nents. The first component is the dose for the first 8 ablation and treatment of thyroid remnants after surgi-hours (0.33 day) after administration. This component cal removal of the thyroid for thyroid cancer. If these comes directly from Equation B-1 using the physical values have been measured for a specific individual, the half-life and a factor of 80 percent. The second compo- measured values may be used.
nent is the dose from the extrathyrial component The record of the patient's release required by 10 from 8 hours to tot jecay. In this component, the first CFR 35.75(c) is described in Regulatory Position 3.1 of C exponential factor represents the activity at t = 8 hours this guide. based on the physical half-life ofiouine-131. The sec-ond exponential factor represents the activity from t = 8 Example 2, Thyroid Cancer: Calculate the maxi- h hours to total decay based on the effective half-life of mum likely dose to an individual exposed to a patient the extrathyroidal component. The third component, who has been administered 7,400 megabecquerels (200 the dose from the thyroidal component for 8 hours to millicuries) of iodine-131 for the treatment of thyroid total decay, is calculated in the same manner as the sec. remnants and metastases. ond component. The full equation is shown as Equa- Solution: In this example, we will calculate the tion B-5. dose by using Equation B-5 to account for the elimina-
- ion ofiodine-131 from the body, based on the effective half-lives appropriate for thyroid cancer. The physical D(=) 34.6ro,, Ei T,(0.8)(1 - e-""*23Wr) half-life and the exposure rate constant are from Table A-1. The uptake fractions and effective half-lives are from Table B-1. An occupancy factor, E, of 0.75 at 1
+ e -o eu<o 333/1, Ei FiT n + e -o.6,3to 333/7PEFT.n}
2 2 2 meter will be used for the first component because the (Equation B-5) time period under consideration is less than I day. However, for the second and third components, an Ft = Extrathyroidal uptake fraction occupancy factor of 0.25 will be used because (1) the F, = Thyroidal uptake fraction effective half-life associated with the dominant compo-nent is greater than 1 day and (2) patient-specific Et = Occupancy factor for the first 8 hours questions were provided to the patient topcify the }, Table B-1. Uptake Fractions and Effective IIalf Lives for Iodine-131 Treatments Extrathyroidal Component Thyroidal Component Uptake Fraction Effective IIalf Life Uptake Fraction Effective IIalf Life Medical Condition F3 T teft (day) F2 T2 err (day) liyperthyroidism 0.20' O.322 0.801 5.21 ; Postthyroidectomy for 0.953 0.322 0.053 7.32 Thyroid Cancer
! M.G. Stabin et al.." Radiation Dosimer"' for the Adult Female and Fet.as from Iodine-131 Admimstration in Hyperthyroidism."lournalofNuclear Medicine. Volume 32, Number 5, May 19W. The thyroid uptake fraction of 0.80 was selected as one that is seldom exceeded by the data rhown in Figure 1 in this referenced document. The effective half-hfe of 5.2 days for the thyroidal component w as derived from a biological half-hfe of 15 days,w hich was obtained from a st:aight-hne fit that accounts for about 75 percent of the data points show n in Figure 1 of thisjournalo/Nuc! car Medicine docu-ment.
2 International Commission on Radiological Protection (ICRP)," Radiation Dose to Patients from Radiopharmaceuticals," ICRP Pubhcation No 53, March 1987. (Available for sale from Pergamon Press,Ir es Elmsford, NY 10523.) The data in this ICRP document suggest that the extrathyroidal component effective l d 'ife in normat subjects is about 0.32 days. Lacking other data, this value is apphed to hy perthyroid and thy road cancer ps .cnts. For thy roid cancer, the Gyroidal component effective half-hfe of 7.3 days is based on a biological half hfe of 80 days (adult thyroid) as suggnied in thia ICRP document. 3 The thyroidal upiate fraction of 0.05 was recommended by Dr M. Pollycove, M.D.. NRC medical visiting fellow, as ao up[ "mit postthyroidectomy for thyroid cancer. 8.39 -16
occupancy factor (see Section B.1.2, " Occupancy Fac-tors To Consider for Patient-Specific Calculations," of (3 this Appendix B). p( .) . 3u(2.2p) {(g ,,)(, g4)(g ,)(l _ c ,,ng,,,,,)
' (i ")*
Vl Substituting the appropriate values into Equation l B-5, the dose to total decay is + c - 6""v8 " (0.25)(0.20)(0.32) '
+ e-06%o333/sN(0.25)(0E0x52)}
D(a) " 3u(2.2x200) Wxmxogi e *"p>N) D(x) = 4.86 mSv (0.486 rem) (ioo cmj2 Therefore, hyperthyroid patients administered 2,035 megabecquerels (55 millicuries) of iodine-131
+ e-a6%a33us"(0.25)(0.95)(0.32) would not have to remain under licensee control and
+ c-o6%c33us04(0.25xo.05)(7.3)} could be released under 10 CFR 35.75 when the occu- l pancy factor of 0.25 in the second and third components of the equation is justified.
In the example above, the thyroidal fraction, F2 = D(m) = 4.53 niilimeverts (0.453 rem) 0.8, s a conservative assumption for persons who have Therefore, thyroid cancer patients administered this treatment for hyperthyroidism. If F 2 has been 7,400 megabecquerels (200 millicuries) ofiodine-131 measured for a specific patient, the measured value may be used. or less would not have to remain under licensee control and could be released under 10 CFR 35.75, assuming B.3 INTERNAL DOSE that the foregoing assumptions can be justified for the individual patient's case and that the patient is given in-ra .n es,su as dine 431, there structions. Patients administered somewhat larger ac- may be concerns that the internal dose of an individual n tivities could also be released immediately if the dose is fr m xp sur t ar leased patientcouldbesignificant.
) not greater than 5 millisieverts (0.5 rem). A rough estimate of the maximum likely committed ef-t(j fective dose equivalent from internal exposure caa be In the example above, the thyroidal fraction, F2 = ' """
0.05, is a conservative assumption for persons who Di = O(10-5)(DCF) (Equation B-6) have had surgery to remove thyroidal tissue. If F2has Where D i = Maximum likely internal committed been measured for a specific patient, the measured value may be used. effective dose equivalent to the indi- , vidual exposed to the patient in rems i Example 3, Ilyperthyroidism: Calculate the O = Activity administered to the patient maximum like!y dose to an individual exposed to a pa. in millicurie; i tient who has bm administered 2,035 megabecquerels 10-5 = Assumed fractional intake 1 (55 millicuries) of iodine-131 for the treatment of hy-perthyroidism (i.e., thyroid ablation). DCF = Dose conversion factor to convert an intake in millicuries to an internal ! Solution: In this example, we will again calculate c mmitted effective dose equivalent I tht dose using Equation B-5, Table A-1, and Table (such as tabulated in Reference ! B-1 to account for the elimination of iodine-131 from - I' the body by using the effective half-lives appropriate Equation B-6 uses a value of10-5 as the fraction of for hyperthyroidism. An occupancy factor, E,of 0.25 at the activity administered to the patient that would be 1 meter will be used for the seccmd and third compo- taken in by the individual exposed to the patient. A nents of the equation because patient-specific instruc- common rule of thumb is to assume that no more than I { tions were provided tojustify the occupancy factor (see millionth of the activity being handled will become an Section B.I.2, " Occupancy Factors To Consider for intake to an individual working with the material. This Patient-Specific Calculations"). rule of thumb was developed in Reference B-3 for cases of worker intakes during normal workplace op-Substituting the appropriate values into Equation erations, worker intalces from accidental exposures, B-5, the dose to total decay is and public intakes from accidental airborne releases 8.39 -17
Substituting the appropriate values into Equation from a facility, but it does not specifically apply for B-6, the maximum internal dose to the person is cases of intake by an individual exposed to a patient. llowever, two studies (Refs. B-4 and B-5) regarding D = (33 mci)(10-5)(53 rem / mci) the intakes of individuals exposed to patients adminis-Di a 0.17 mSv (0.017 rem) tered iodine-131 indicated that intakes were generally In this rase, the external dose to the other person of the order of 1 millionth of the activity administered would be no gieater than 5 millisieverts (0.5 rem), to the patient and that internal doses were far below ex-ternal doses. To account for the most highly exposed in- while the internal c se would be about 0.17 millisievert dividual and to add a degree of conservatism to the cal- (0.017 rem). Thus, the internal dose is about 3 percent of the external gamma dose. Internal doses may be ig-culations, a fractional transfer of 10-5 has been nored in the calculations if they are likely to be less than assumed. 10 percent of the external dose since the internal dose would be signincantly less than the uncertainty in the Example 4, Internal Dose: Using the ingestion external dose. pathway, calculate the maximum internal dose to a per-son exposed to a patient who has been administered The conclusion that internal contamination is rela-1,110 megabecquerels (33 millicuries) of iodine-131. tively unimportant in the case c. patient release was The ingestion pathway was selected since it is likely also reached by the NCRP. The NCRP addressed the that most of the intake would be through the mouth or risk ofintake of radionuclides from patients' secretions through the skin, which is most closely approximated and excreta in NCRP Commentary No.11," Dose Lim-its for Individuals Who Receive Exposure from Radio-by the ingestion pathway, nuclide Therapy Patients"(Ref. B-6). The NCRP con-Solution: This is an example of the use of Equa- cluded, "Thus, a contamination incident that could lead to a significant intake of radioactive material is very un-tion B-6. The dose conversion factor DCF for the in-likely." For additional discussion on the subject, see gestion pathway is 53 rems /millicurie from Table 2.20f Reference B-1. Reference B-2. 9 0 0 8.39 - 18
l REFERENCES FOR APPENDIX B B-1. S. Schneider and S.A. McGuire, " Regulatory B-3. A. Brodsky, "Resuspension Factors and Proba-
/O Analysis on Criteria for the Release of Patients d Administered Radioactive Material," USNRC, NUREG-1492, February 1997.*
bilities of Intake of Material in Process (or 'Is 10-6 a Magic Number in Health Physics?')," i p Health Physics, Volume 39, Number 6,1980. B-2. K.E Eckerman, A.B. Wolbarst, and A.C.B. Rich- B-4. R.C.T. Buchanan and J.M. Brindle, "Radiciodine ardson, Limiting Values of Radionuclide Intake Therapy to Out-patients-The Contamination
- and Air Concentration and Dose Conversion Hazard," British Journal of Radiology, Volume i Factors for Inhalation, Submersion, and Inges- 43,1970. >
tion, Federal Guidance Report No.11, U. S. Envi-ronmental Protection Agency, Washington, DC, B-5. A.P. Jacobson, P.A. Plato, and D. Toeroek, " Con-
- 1988, tamination of the Home Environment by Patients '
Treated with Iodine-131," American Journal of f
- Copies may be purchased at current rates from the U. S. Government Print-
" ' " ho"
$235l$*itSi9oro he on chn c 1 I or ion e c, by B-6. National Counc9 on Radiation Protection and writing NTIS at 5285 Port Royal Road, Springfield, VA 22161. Copics of Measurements, Dose Limits for Individuals )
f' ' " NRC i ('biIc'Nm'd'ik'*m ai N'2E'N"'t e l i g), ora N t ece to ng Who Receive Exposure from Radionuclide Ther- l DC. The PDR's mailing address is Mail Stop LIA, Washington. DC apy Patients," Commentary No.11, February 28, l 20555; telephone (202)634-3273; fax (202)634- 3343. 1995.
' ("N REGULATORY ANALYSIS
" Regulatory Analysis on Criteria for the Release of Patients Administered Ra-dioactive Material"(NUREG-1492, February 1997), provides the regulatory ba-sis for this guide and examines the costs and benefits. A copy of NUREG-1492 is
'avaihble for inspection and copying for a fee at the NRC Public Document Room, 2120 L Street NW., Washington, DC. Copies may be purchased at current rates from the U.S. Government Printing Office, P.O. Box 37082, Washington, DC 20402-9328 (telephone (202)512-2249); or from the National Technical Informa-tion Service by writing NTIS at 5285 Port Royal Road, Springfield, VA 22161. I l
8.39 -19
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