Patient Release Calculator
Estimates the dose to the individual most likely to be exposed to a patient who has been administered radioactive material, and whether the patient may be released under 10 CFR 35.75, using NRC Regulatory Guide 8.39, Rev. 1 (April 2020).
Want to use the methodology in draft DG-8061 (proposed Reg Guide 8.39, Rev. 2)?
Using draft DG-8061 methodology.
Patient information (optional)
Optional. Appears only on your printout. Nothing entered here is sent anywhere or saved.
Radionuclide and administered activity
Patient-specific factors
Uses the I-131 two-component model (Reg Guide 8.39, Rev. 1, Appendix B, Eq. B-5). Occupancy: 0.75 for the first 8 hours, then 0.25.
Release instructions this calculation assumes
Occupancy factor: 0.25 at 1 m, assuming the patient receives release instructions.
Release instructions this calculation assumes
Assessment tier (DG-8061 draft)
The first tier assumes 100% occupancy at 1 m, physical decay only, and no tissue attenuation. The second tier multiplies that dose by four patient-specific factors: D = 1.44·Tr·Δpr·A0·FB·FO·FG·FA.
FB: biokinetics
Fraction of the total disintegrations that occur in the patient.
FO: occupancy
Fraction of the patient’s total emitted exposure that the maximally exposed bystander receives.
FG: geometry
Adjusts for the actual distance and how the activity is distributed (DG-8061 Table B-1).
FA: attenuation
Photon scatter, buildup, and absorption in the patient’s tissue. Can be greater than 1.
Dose to the maximally exposed individual
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Can this patient be released?
Enter activityEquation, parameters and references
Privacy: no information is collected or stored
This calculator runs entirely in your web browser. Nothing you enter, including optional patient information, is transmitted to, collected by, or stored by Olympic Health Physics, Inc. or this website, and it is cleared when you reload or close the page. If you print or save a copy, you are responsible for protecting it under your facility’s privacy policies and applicable law, including HIPAA.
Disclaimer and limitation of liability
This calculator is provided by Olympic Health Physics, Inc. for general informational and educational purposes only, “as is” and without warranty of any kind, express or implied, including any warranty of accuracy, completeness, or fitness for a particular purpose. It is not professional, medical, legal, or regulatory advice and does not replace the judgment of your Authorized User, Radiation Safety Officer, or qualified medical physicist. You are solely responsible for verifying all inputs, assumptions, and results; for confirming that the method used is appropriate for your patient; and for complying with 10 CFR 35.75, 10 CFR 35.2075, your license conditions, and any Agreement State requirements, which may differ from NRC guidance. Use of this calculator is entirely at your own risk. To the fullest extent permitted by law, Olympic Health Physics, Inc. and its officers, employees, and agents are not liable for any direct, indirect, incidental, consequential, or other damages arising from the use of, or reliance on, this calculator or its results. Using this calculator means you accept these terms.
References: U.S. NRC Regulatory Guide 8.39, Rev. 1, “Release of Patients Administered Radioactive Material” (April 2020). U.S. NRC Draft Regulatory Guide DG-8061, proposed Rev. 2 to Reg Guide 8.39 (April 2023; draft for comment, not approved). This calculator does not address breastfeeding infants or children, internal dose, or incontinent or dialysis patients.