TPM-B - Medical Health Physics Part 2 Orlando V 14:30 - 16:45
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| Chair(s): Thomas Morgan, Muhammad Maqbool
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TPM-B.1
14:30 The Development, Validation, And Application Of A Monte Carlo-based CBCT Model To Investigate Patient Size Impact On Organ Dose HK Niskanen*, Rensselaer Polytechnic Institute
; PF Caracappa, Columbia University; XG Xu, Rensselaer Polytechnic Institute
Abstract: Image-guided radiotherapy has become the standard of care in medical institutions for improving the accuracy during radiotherapy, and cone-beam CT (CBCT) scans are generally performed for each treatment fraction to monitor the target volume geometry changes and ensure correct positioning. While the imaging dose from a single scan is small, a full course of treatment may include many scans, and therefore, the accumulated dose for the entire treatment can be significant. Despite the possibility of delivering significant dose to critical organs, increasing the risk of developing secondary cancer, the imaging dose is not included in radiotherapy planning. A recent AAPM Task Group Report 180 provided recommendations for assessing concomitant imaging dose and techniques for reducing it, and concluded that the proper management of IGRT imaging dose includes adhering to ALARA principles by minimizing dose as much as possible. The need to assess the risk associated with CBCT scans can be achieved through the use of computational models of CBCT scanners and patient phantoms for organ dose computations. This work describes the development and validation of two CBCT scanners in wide clinical use, the Varian OBI and Elekta XVI, using the Monte Carlo method. Computational phantoms were then integrated with the model to assess organ dose from clinical CBCT scans. The validated CBCT scanner models were then used to assess organ dose to phantoms of different body mass. The thymus received the highest dose in case of the chest scan, where the absolute dose varied from 4.7 to 7.3 mGy (OBI) and 16.9 to 23.3 mGy (XVI). The prostate received the highest dose in case of the pelvic scans for males, with the dose varying from 9.3 mGy to 27.3 mGy. For females, the small intestine received the highest dose with a range of 6.1 mGy to 30.5 mGy. The XVI system was found to deliver considerably higher absolute doses due to the higher tube current used in the clinical protocols.
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TPM-B.2
14:45 Occupational Radiation Exposures to Clinical Staff Working With I-131-Iomab-B F Safavi, Actinium Pharmaceuticals, Inc.
; S Konerth, Versant Medical Physics and Radiation Safety; DR Fisher, Versant Medical Physics and Radiation Safety; Q Liang*, Actinium Pharmaceuticals, Inc.; V Reddy, Actinium Pharmaceuticals, Inc.; MS Berger, Actinium Pharmaceuticals, Inc.
Abstract: Background and Purpose. Acute myeloid leukemia in older patients is difficult to treat due to the toxicity of most therapeutic agents. However targeted high-dose radioimmunotherapy using iodine-131-anti-CD45-Apamistamab (I-131-Iomab-B, Actinium Pharmaceuticals, Inc.) has shown potential to improve survival rates in patients who progressed on conventional salvage chemotherapies. A phase III clinical trial with I-131-Iomab-B is currently being conducted at 18 major medical centers in the U.S. and Canada. The SIERRA trial provides a therapeutic dose delivered to the target organ (bone marrow) without exceeding radiation dose tolerances to normal organs (liver, spleen). The purpose of this presentation is to describe the safety measures, education, training, and customized shielding used for this study. Methods. Exposure data for approximately 32 health care personnel collaborating in the ongoing SIERRA study were collected from four participating sites. Results. Health care personnel exposure levels were minimal (approximate mean of 0.13 mSv and median of 0.064 mSv) for those caring for SIERRA study participants who received between 12.9 GBq to 38.1 GBq of I-131-Iomab-B. Methods of radiation safety, training and customized shielding, low exposure levels will be described. Conclusions. This review of personnel radiation exposure levels indicates that targeted radioimmunotherapy with I-131-Iomab-B can be accomplished with minimum additional exposure to staff members. This is achieved through training, education and customized physical shielding for creating more advanced safety procedures and to decrease the exposure for this ongoing study. Support. Actinium Pharmaceuticals, Inc., New York, New York.
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TPM-B.3
15:00 The Adventures of a Health Physicist in Nuclear Medicine as a Patient DB Schultz*, United States Military Academy
Abstract: The presenter underwent several nuclear medicine procedures at a major New York City hospital and was surprised by the inadequacies of the patient radiation safety briefs he received, lack of general radiation protection knowledge of the nuclear medicine staff, and lack of consistency between repeated procedures. The presentation will describe his experiences with two CT scans, multiple MRIs, a PET/CT scan, and a gallium scan. The presentation will include graphs of radiation dose rates coming from the presenter with time after being administered gallium-67 and fluorine-18, yielding effective half-lives of (2.92 ± 0.04) d for gallium-67 and (96 ± 6) min for fluorine-18. The presenter will also discuss what he believes should have been included in the patient radiation safety briefs. This information should help health physicists working in hospitals better monitor and train nuclear medicine staff to better inform and protect patients and their families before and after nuclear medicine procedures.
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TPM-B.4
15:15 Estimation of External Dose Rates to Hotel Workers from I-131 Patients C Foreman, Texas A&M University
; SA Dewji*, Texas A&M University
Abstract: Iodine-131 is commonly used in medical diagnosis and therapy for patients with hyperthyroidism or differentiated thyroid cancer. Following treatment, patients often recuperate in a hotel room to avoid exposing family members. The main purpose of this study was to estimate effective dose rate coefficients to a hotel worker who handles potentially contaminated bed linens due to secretions by 131I patients as sweat or urine. The external dose rate estimates were derived using Monte Carlo methods and the Phantom with Movable Arms and Legs (PIMAL), to model a housekeeper standing in an upright position holding a pile of bed sheets. Simulations further integrate the body burden of time-dependent biokinetic metabolism of 131I in the patients body. Organ absorbed dose rate and effective dose rate coefficients were calculated for three scenarios of bed linen contamination, and compared to maximum allowable values reported in the U.S. Nuclear Regulatory Guide 8.39, and to previous work examining dose rates to members of the public due to exposure to patients with 131I treatment.
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TPM-B.5
16:00 Radioactive Decedants - What are the Risks? MA Miller*, Cleveland Clinic
; GM Sturchio, Mayo Clinic
Abstract: The use of radioactive materials for therapies is done safely, in accordance with regulations and often has very successful results for patients. There are rare times when a patient passes away before the administered activity has been eliminated or decayed to a negligible level. The deceased are handled in a variety of ways from death to burial or cremation; each with potential pathways for family member or mortuary workers to receive radiation exposure. We will discuss these exposure pathways, provide exposure estimates (using calculations or measurements) to support dose assessments, and provide recommendations for consideration by licensees and regulators.
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TPM-B.6
16:15 Functions of the Nuclear Regulatory Commission Advisory Committee on the Medical Uses of Isotopes - Part I MA Sheetz*, University of Pittsburgh
; S Holiday, US Nuclear Regulatory Commission
Abstract: The Advisory Committee on the Medical Uses of Isotopes (ACMUI) advises the U.S. Nuclear Regulatory Commission (NRC) on policy and technical issues that arise in the regulation of the medical uses of radioactive material in diagnosis and therapy. The ACMUI membership includes health care professionals from various disciplines, who comment on changes to NRC regulations and guidance; evaluate certain non-routine uses of radioactive material; provide technical assistance in licensing, inspection, and enforcement cases; and bring key issues to the attention of the Commission for appropriate action. The ACMUI originated out of the subcommittee of experts who reviewed and approved the distribution of radioactive isotopes as part of the Manhattan Project, and later the Atomic Energy Commission (AEC). As an official advisory body to the NRC staff, the ACMUI's operational practices are governed by the provisions of the Federal Advisory Committee Act (FACA) and NRC's regulations in 10 CFR Part 7. This presentation will provide an overview of the ACMUIs reporting structure, functions, and recent hot topic issues on which it has reported such as: Patient Release Criteria, Physical Presence Requirements for Leksell Gamma Knife Icon and Perfexion, Germanium-68/Gallium-68 Pharmaceutical Grade Generators Licensing Guidance, and Authorized User Training and Experience Requirements under 10 CFR 35.390.
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TPM-B.7
16:30 Functions of the Nuclear Regulatory Commission Advisory Committee on the Medical Uses of Isotopes - Part II S Holiday*, US Nuclear Regulatory Commission
; MA Sheetz, University of Pittsburgh
Abstract: The Advisory Committee on the Medical Uses of Isotopes (ACMUI) advises the U.S. Nuclear Regulatory Commission (NRC) on policy and technical issues that arise in the regulation of the medical uses of radioactive material in diagnosis and therapy. The ACMUI membership includes health care professionals from various disciplines, who comment on changes to NRC regulations and guidance; evaluate certain non-routine uses of radioactive material; provide technical assistance in licensing, inspection, and enforcement cases; and bring key issues to the attention of the Commission for appropriate action. The ACMUI originated out of the subcommittee of experts who reviewed and approved the distribution of radioactive isotopes as part of the Manhattan Project, and later the Atomic Energy Commission (AEC). As an official advisory body to the NRC staff, the ACMUI's operational practices are governed by the provisions of the Federal Advisory Committee Act (FACA) and NRC's regulations in 10 CFR Part 7. This presentation will provide an overview of the ACMUIs reporting structure, functions, and recent hot topic issues on which it has reported such as: Patient Release Criteria, Physical Presence Requirements for Leksell Gamma Knife Icon and Perfexion, Germanium-68/Gallium-68 Pharmaceutical Grade Generators Licensing Guidance, and Authorized User Training and Experience Requirements under 10 CFR 35.390.
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TPM-B.8
16:45 Assessment of Reference Dose Associated with Computed Tomography Examination SH Allehyani*, Medical Physics Division
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