2020 Health Physics Society Midyear Meeting & ExhibitionWAM-A
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| Chair(s): Matthew Arno, Teresa Fisher |
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WAM-A.1 10:00 Mechanisms Underlying Electromagnetic Interference To Cardiovascular Implantable Electrical Devices. Dopart Pamela J, Exponent; Cotts Benjamin RT*, Exponent pdopart@exponent.com
Cardiovascular Implantable Electrical Devices or CIEDs such as pacemakers or implantable cardioverter defibrillators (ICDs) are life-saving medical devices used by a growing number of patients and which are potentially susceptible to electromagnetic interference (EMI) from a variety of sources, including metal detectors, anti-theft gates, and communication devices. Exposure of patients to electromagnetic signals from wireless communication and charging sources, including from medical devices, are expanding at an ever-increasing rate, due to the increase of wirelessly-connected devices as part of the “Internet of Things” and the introduction of 5G mobile technology. The frequency, modulation format, duration and power of the signal from these sources all can play an important role in the potential for EMI. This presentation provides an overview of the coupling mechanisms for potential interference of electromagnetic sources with CIEDs and a discussion of the characteristics of electromagnetic sources currently in use and those expected to be introduced in the near future. In addition, a brief discussion of the evaluation and mitigation of risk of a potential adverse event related to EMI and CIEDS is presented. |
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WAM-A.2 10:15 Public Dose Assessment from Canine Treatment with Sn-117m. Arno Matthew G*, Foxfire Scientific; Smith Chad , FX Masse; Donecker John M, Exubrion Therapeutics; Stevenson Nigel R., Exubrion Therapeutics arno@foxfirescientific.com
US Nuclear Regulatory Commission (NRC) detailed guidance for release of animals injected with radioactive materials is specific to and limited to feline hyperthyroidism treatment with I-131. A treatment for dogs with osteoarthritis has been developed that involves the injection of a Sn-117m colloid into the affected joint(s). A major issue with successfully licensing this treatment is ensuring that no member of the public will receive a dose in excess of 1 mSv. Discussions with the NRC indicates that issues that needed to be addressed included the nature of human-dog interactions, occupancy factors, and the reliance upon and specificity of written instructions. Therefore, detailed investigations were performed to determine the nature of human-dog interactions as part of a time and motion study in conjunction with the treatment specific radioactive material characteristics and biokinetics. The results of these investigations were used to calculate the hypothetical doses from typical human-dog interactions and develop the necessary written instructions for the caregivers (dog owners and household members) to keep doses below the regulatory limit that were modeled after the existing guidance for feline hyperthyroidism treatment. |
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WAM-A.3 10:30 Health Physics Analysis of Cs-131 Mesh Implants for Colorectal Cancer - An Update. Chang Lienard A*, Houston Methodist Hospital; Patel Pankaj, Houston Methodist Hospital; Alvarez Hope, Houston Methodist Hospital; Quan Enzhuo M, Houston Methodist Hospital; Farach Andrew M, Houston Methodist Hospital LienardAC@gmail.com
At the HPS 64th Annual Meeting in Orlando, Florida, we presented a health physics analysis from three Cs-131 brachytherapy procedures. The first was an open-cavity mesh implant while another was a robotically insertion of a mesh implant, both for colorectal cancer patients. The third involved loose seed implantation for a patient with vaginal cancer. Since then, we have had three additional procedures (also one open cavity mesh, one robotic mesh and one outpatient loose seed insertion) that presented us with new challenges and additional data to assess exposure to patients, OR staff, medical physicists, and the public. While the health physics team have no official roles in the actual procedures themselves, there is a large undertaking behind the scenes to ensure everything is in order from a regulatory standpoint, as well as making sure that all staff in the post-implantation patient flow are trained and comfortable with radioactive patients. In terms of the exposure rates, the highest exposure from 1 m from the implants was 0.74 mR/hr, well below our calculated discharge limit derived from Nuclear Regulatory Commission Guide 8.39. Area monitors were placed in nursing stations and some personal dosimeters were issued as well, which all came out minimal. Inside the operating rooms, the highest dose rates appeared unsurprisingly for the radiation oncologist and the medical physicist handling the mesh/seeds, but dosimeter readings are also expected to come out minimal. Exposure rates to the nursing staff and anesthesiology team were also of minimal concern. |
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WAM-A.4 10:45 First in U.S. Clinical Administration of Th-227. Fisher Teresa*, National Institutes of Health teresa.fisher@nih.gov
In July, 2019 the first targeted thorium conjugate patient in the United States was treated. There were many hurdles to overcome in order to prepare for this treatment. These included getting proper classification of Th-227 for clinical use, license amendments, delivery logistics, instrumentation challenges, staff training, and more. This talk summarizes the 18-month journey from the initial proposal to patient administration. |
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WAM-A.5 11:00 Understanding the Measurement of 227Th Activity in Targeted Alpha-Emitting Radiotherapy using a Dose Calibrator. Munger Eric J*, NIH; Maass-Moreno Roberto, NIH mungerej@mail.nih.gov
Dose calibrator measurements in clinical trials with Targeted 227Th Conjugates (TTC) are needed to maintain and document adherence with IRB approved protocol requirements and federal regulation promulgated to protect patients receiving both diagnostic and therapeutic radiopharmaceutical treatments. Clinical doses of 227Th are required to be measured by a dose calibrator, configured appropriately to specific dial settings outlined in the Bayer-recommended settings using a certified 227Th check source. Understanding the physics behind the method of setting the dials is critical for Health Physicists before enrollment of patients in the clinical trial. |
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WAM-A.6 11:15 The Potentials Of EXPLORER For Low Dose, Total Body PET/CT Imaging. Kroger Linda A*, UC Davis; Cherry Simon R, UC Davis; Badawi Ramsey D, UC Davis lakroger@ucdavis.edu
Use of positron emission tomography integrated with computed tomography (PET/CT) has transformed nuclear medicine imaging. PET/CT with F18-fluorodeoxyglucose (FDG) for tumor staging and evaluation of treatment response is a mainstay in oncology and potential uses of PET/CT in other areas of medicine and research are numerous. EXPLORER is a revolutionary, total-body PET/CT that was conceptualized and built by a multi-institutional group designed for a wide range of clinical and biomedical research applications. To date it is the world’s highest sensitivity PET scanner. This high sensitivity allows for performance of scans with very low doses of radiotracer and acquisition of whole-body dynamic images in less than 1 minute. Total-body functional imaging applications include studies of trafficking patterns in cell-based therapies, evaluation of new drug pharmacokinetics across all organs, studies of metabolic disorders and autoimmune disease as well as other chronic conditions. One area of interest is pediatrics. Despite its great potential, use of PET/CT in children has been restricted because of concerns over radiation dose and the need for anesthesia. Much effort has been devoted to lower radiation dose in imaging through the Image Gently campaign. One goal of EXPLORER is to reduce the total radiation dose of a whole-body PET/CT examination to less than 1 mSv. Because of increased signal capture, the dose of FDG can be reduced by a factor of 20 or more compared to conventional PET. This reduction in FDG can reduce the effective dose to less than 0.5 mSv and efforts to reduce the CT dose are underway. The EXPLORER scanner will allow total-body and functional PET/CT to be used widely and safely in both adults and children. |