Applications of justification and optimization in medical imaging: examples of clinical guidance for computed tomography use in emergency medicine.

Availability, reliability, and technical improvements have led to continued expansion of computed tomography (CT) imaging. During a CT scan, there is substantially more exposure to ionizing radiation than with conventional radiography. This has led to questions and critical conclusions about whether the continuous growth of CT scans should be subjected to review and potentially restraints or, at a minimum, closer investigation. This is particularly pertinent to populations in emergency departments, such as children and patients who receive repeated CT scans for benign diagnoses. During the last several decades, among national medical specialty organizations, the American College of Emergency Physicians and the American College of Radiology have each formed membership working groups to consider value, access, and expedience and to promote broad acceptance of CT protocols and procedures within their disciplines. Those efforts have had positive effects on the use criteria for CT by other physician groups, health insurance carriers, regulators, and legislators.

Applications of justification and optimization in medical imaging: examples of clinical guidance for computed tomography use in emergency medicine.

Availability, reliability, and technical improvements have led to continued expansion of computed tomography (CT) imaging. During a CT scan, there is substantially more exposure to ionizing radiation than with conventional radiography. This has led to questions and critical conclusions about whether the continuous growth of CT scans should be subjected to review and potentially restraints or, at a minimum, closer investigation. This is particularly pertinent to populations in emergency departments, such as children and patients who receive repeated CT scans for benign diagnoses. During the last several decades, among national medical specialty organizations, the American College of Emergency Physicians and the American College of Radiology have each formed membership working groups to consider value, access, and expedience and to promote broad acceptance of CT protocols and procedures within their disciplines. Those efforts have had positive effects on the use criteria for CT by other physician groups, health insurance carriers, regulators, and legislators.

Summary of workshop on CT in emergency medicine: ensuring appropriate use.

This paper addresses the increasing use of CT in medical radiologic imaging, with a focus on applications in emergency medicine. The rapidly increasing use of CT in medical imaging over the past 3 decades has been a major subject in many recent publications, including a discussion of concerns about patient radiation doses, unnecessary CT examinations, and the costs of CT examinations. One area of these concerns has been the use of CT examinations for triage, selection of treatment options, and release of patients from emergency medical settings. On September 23 and 24, 2009, the National Council on Radiation Protection and Measurements held a workshop on appropriate uses of CT imaging with emergency patients. The workshop was cosponsored by 8 private and government organizations: the American Association of Physicists in Medicine, the American College of Emergency Physicians, the ACR, the American Society of Emergency Radiology, the Centers for Disease Control and Prevention, Landauer, Inc, the Society for Academic Emergency Medicine, and the US Environmental Protection Agency. This paper presents a summary of discussions at the workshop and recommendations for important areas of consideration in a subsequent consensus paper to be prepared on clinical guidance for applications of CT in emergency medicine procedures.

Panel session on "how to meet the challenges for nuclear power".

This panel session at the 2009 Annual Meeting involved a discussion of views of government, industry, and national research laboratory members on the primary future goals in developing advanced nuclear reactor and nuclear fuel cycle designs, fuel management, and used fuel disposal options. The session at the 2009 NCRP Annual Meeting on "How to Meet the Challenges for Nuclear Power" was chaired by Mary E. Clark of the U.S. Environmental Protection Agency and focused on efforts in the United States and worldwide to expand nuclear capabilities for electric power production in a safe, secure, and environmentally acceptable manner. This paper briefly summarizes the key topics discussed in five presentations during this session of the NCRP Annual Meeting.

Perspectives of U.S. government agencies on the potential role of greater scientific understanding of low-dose radiation effects in establishing regulatory health protection guidance.

This paper summarizes the perspectives of three U.S. federal agencies on the potential long-term influence of new findings on the biological and potential health effects of low dose and low dose-rate radiation on regulatory controls placed on exposures in occupational, medical, and public settings.

Magnetically induced electric fields and currents in the circulatory system.

Blood flow in an applied magnetic field gives rise to induced voltages in the aorta and other major arteries of the central circulatory system that can be observed as superimposed electrical signals in the electrocardiogram (ECG). The largest magnetically induced voltage occurs during pulsatile blood flow into the aorta, and results in an increased signal at the location of the T-wave in the ECG. Studies involving the measurement of blood pressure, blood flow rate, heart sounds, and cardiac valve displacements have been conducted with monkeys and dogs exposed to static fields up to 1.5 tesla (T) under conditions producing maximum induced voltages in the aorta. Results of these studies gave no indication of alterations in cardiac functions or hemodynamic parameters. Cardiac activity monitored by ECG biotelemetry during continuous exposure of rats to a 1.5-T field for 10 days gave no evidence for any significant changes relative to the 10 days prior to and following exposure. Theoretical modeling of magnetic field interactions with blood flow has included a complete solution of the equation describing the flow of an electrically conductive fluid in the presence of a magnetic field (the Navier-Stokes equation) using the finite element technique. Magnetically induced voltages and current densities as a function of the applied magnetic field strength have been calculated for the aorta and surrounding tissues structures, including the sinoatrial node. Induced current densities in the region of the sinoatrial node are predicted to be >100 mA/m2 at field levels >5 T in an adult human under conditions of maximum electrodynamic coupling with aortic blood flow. Magnetohydrodynamic interactions are predicted to reduce the volume flow rate of blood in the human aorta by a maximum of 1.3%, 4.9%, and 10.4% at field levels of 5, 10, and 15 T, respectively.

Future role of the NCRP in radiation health protection.

The predecessor organizations of the National Council on Radiation Protection and Measurements (NCRP) were established in 1929 (the U.S. Advisory Committee on X-Ray and Radium Protection) and in 1946 (the National Committee on Radiation Protection and Measurements). In 1964, the NCRP was formally chartered by the U.S. Congress as a national resource for scientific guidance on issues related to radiation measurements and health protection. In this paper the history and scientific contributions of NCRP are reviewed, followed by a discussion of its evolving mission and future scientific goals.

Large-scale purification of 90Sr from nuclear waste materials for production of 90Y, a therapeutic medical radioisotope.

A major limitation on the supply of the short-lived medical isotope 90Y (t1/2 = 64 h) is the available quantity of highly purified 90Sr generator material. A radiochemical production campaign was therefore undertaken to purify 1,500 Ci of 90Sr that had been isolated from fission waste materials. A series of alkaline precipitation steps removed all detectable traces of 137Cs, alpha emitters, and uranium and transuranic elements. Technical obstacles such as the buildup of gas pressure generated upon mixing large quantities of acid with solid 90Sr carbonate were overcome through safety features incorporated into the custom-built equipment used for 90Sr purification. Methods are described for analyzing the chemical and radiochemical purity of the final product and for accurately determining by gravimetry the quantities of 90Sr immobilized on stainless steel filters for future use.

The wonders of magnetism.

In this acceptance address for the Bioelectromagnetics Society's 2001 d'Arsonval Award, Dr. Tenforde reviews the highlights of the nonionizing field aspects of his research and scientific service career. These are focused in four areas: (a). development and application of microelectrophoretic methods to probe the surface chemistry of normal and cancerous cells; (b). research on the biophysical mechanisms of interaction and the dosimetry of static and extremely low frequency magnetic fields; (c). application of extremely high intensity magnetic fields in several spectroscopic methods for probing the detailed structures of large biological macromolecules; and (d). development of national and international guidelines for the exposure of workers and members of the general public to electromagnetic fields with frequencies spanning the entire nonionizing electromagnetic spectrum.