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Han E, Lee C, McGuire E, et al. SU-E-J-182: Patient Specific Assessment of External Radiation Exposure to Bystanders Interacting with Patients Following 131I Therapy. Med Phys. 2012;39(6):3694doi: 10.1118/1.4735023.
Han, E., Lee, C., McGuire, E., Brown, T., Penagaricano, J., Corry, P., & Bolch, W. (2012). SU-E-J-182: Patient Specific Assessment of External Radiation Exposure to Bystanders Interacting with Patients Following 131I Therapy. Medical physics, 39(6), 3694. https://doi.org/10.1118/1.4735023
Han, E, et al. "SU-E-J-182: Patient Specific Assessment of External Radiation Exposure to Bystanders Interacting with Patients Following 131I Therapy." Medical physics vol. 39,6 (2012): 3694. doi: https://doi.org/10.1118/1.4735023
Han E, Lee C, McGuire E, Brown T, Penagaricano J, Corry P, Bolch W. SU-E-J-182: Patient Specific Assessment of External Radiation Exposure to Bystanders Interacting with Patients Following 131I Therapy. Med Phys. 2012 Jun;39(6):3694. doi: 10.1118/1.4735023. PMID: 28519014.
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Med Phys. 2012 Jun;39(6):3694. doi: 10.1118/1.4735023.

SU-E-J-182: Patient Specific Assessment of External Radiation Exposure to Bystanders Interacting with Patients Following 131I Therapy.

Medical physics

E Han, C Lee, E McGuire, T Brown, J Penagaricano, P Corry, W Bolch

Affiliations

  1. University of Arkansas for Medical Sci, Little Rock, AR.
  2. National Cancer Institute, Bethesda, MD.
  3. University Florida, Gainesville, FL.

PMID: 28519014 DOI: 10.1118/1.4735023

Abstract

PURPOSE: Conventional calculation methods of patient release criteria for compliance with NRC regulations are based on the assumption that both patient and bystander are each a single point in space. This study was intended to assess the patient-specific external radiation exposure to a bystander interacting with the patient following radionuclide therapy with 131I.

METHODS: 131I-sodium iodide treatment for hyperthyroidism and thyroid cancer and 131I-tositumomab treatment of non-Hodgkin's lymphoma were considered. 131I distribution provided by the patient SPECT image was rendered on the SPECT-fused CT images. The CT images were then imported to a Monte Carlo based simulation code, MCNPX 2.7, as a source phantom. For a target phantom, we employed the adult male hybrid phantom developed at the University of Florida and National Cancer Institute. A single orientation - patient and a bystander facing one another at 1.0 m - was considered. S factors (dose per unit cumulative activity (A)) for each organ in a bystander was obtained from the MC calculations and effective dose (EDE) per A was calculated based on tissue-weighted individual organ doses. The results were compared with the calculations using UF/NCI adult hybrid source/target phantoms and the revised adult ORNL stylized source/target phantoms.

RESULTS: EDE per A of the stylized phantom was 1.5% higher than that of the hybrid phantom for uniform source localization in the thyroid. However, EDE per A of the hybrid phantom was 20% less than that of stylized phantoms for a torso source. The difference is attributed to the realistic shape of the frontal body comparing to the simple ellipsoidal trunk of the stylized phantom.

CONCLUSIONS: Based on the realistic hybrid phantoms and accurate MC radiation transport calculation tools, patient specific dosimetry for a bystander is feasible. S factors will be calculated using the patient CT image with 131I bio-distributions and hybrid phantoms.

© 2012 American Association of Physicists in Medicine.

Keywords: Anatomy; Cancer; Computed tomography; Dosimetry; Exposure assessment; Medical imaging; Monte Carlo methods; Radiation treatment; Single photon emission computed tomography

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