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Biomedical subjects

Fred A Mettler

Publications and source records attributed to Fred A Mettler.

11 recordsLinked to original sources
PubMed2005

Reference values for diagnostic radiology: application and impact.

Reference values (RVs) are recommended by the American Association of Physicists in Medicine for four radiographic projections, computed tomography, fluoroscopy, and dental radiography. RVs are used to compare radiation doses from individual pieces of radiographic equipment with doses from similar equipment assessed in national surveys. RVs recommended by the American Association of Physicists in Medicine have been developed from the Nationwide Evaluation of X-ray Trends survey performed by the state radiation protection agencies with the cooperation and support of the U.S. Food and Drug Administration, the Conference of Radiation Control Program Directors, and the American College of Radiology. The RVs selected by the American Association of Physicists in Medicine represent, approximately, the 80th percentile of the survey distributions. Consequently, equipment exceeding the RVs is using higher radiation doses than is 80% of the equipment in the surveys. Radiation doses for specific projections, with standard phantoms, should be measured annually, as recommended by the American College of Radiology. When the RVs are exceeded, the medical physicist should investigate the cause and determine, in cooperation with the responsible radiologist, whether these doses are justified or the imaging system should be optimized to reduce patient radiation doses. RVs are a useful tool for comparing patient radiation doses at institutions throughout the United States and for providing information about radiographic equipment performance.

Equipment Safety↗
PubMed2005

Medical treatment of radiological casualties: current concepts.

The threat of radiologic or nuclear terrorism is increasing, yet many physicians are unfamiliar with basic treatment principles for radiologic casualties. Patients may present for care after a covert radiation exposure, requiring an elevated level of suspicion by the physician. Traditional medical and surgical triage criteria should always take precedence over radiation exposure management or decontamination. External contamination from a radioactive cloud is easily evaluated using a simple Geiger-Muller counter and decontamination accomplished by prompt removal of clothing and traditional showering. Management of surgical conditions in the presence of persistent radioactive contamination should be dealt with in a conventional manner with health physics guidance. To be most effective in the medical management of a terrorist event involving high-level radiation, physicians should understand basic manifestations of the acute radiation syndrome, the available medical countermeasures, and the psychosocial implications of radiation incidents. Health policy considerations include stockpiling strategies, effective use of risk communications, and decisionmaking for shelter-in-place versus evacuation after a radiologic incident.

Environmental Exposure↗
PubMed2005

Medical resources and requirements for responding to radiological terrorism.

Medical planning and response to radiological terrorism is different than planning or responding to an event such as a nuclear power plant accident. The major differences are that now we must plan for multiple simultaneous events, suicide scenarios, and the possibility of biological, chemical, and radiological agents being used at the same time. This demands an "all-hazards" approach and not just a radiological response. An overview of the issues related to diagnosis, treatment, training, and resources is provided. Although the requirements for medical management are clear, the available resources have not been applied in a manner that results in adequate preparedness for radiological events.

Decontamination↗
PubMed2004

Medical perspective on ways to improve radiation protection standards.

Radiation has been used in medical practice for over a century. While hazards were recognized very early, radiation protection in medicine evolved over many subsequent decades. Current issues and problems of radiation protection in medicine are mainly the result of rapidly changing technology and lack of education. With the widespread application of computed tomography and digital radiography, use of high dose radiological equipment by nonradiologists, and continuing accidental exposures in radiation therapy there are problems not envisioned before. Radiation protection in medicine is not likely to be improved significantly simply with the addition of more standards, but it will require a combined approach with the medical and educational communities.

Diagnostic Imaging↗
PubMed2002

CT scanning: a major source of radiation exposure.

CT scanning is a relatively high dose procedure that is becoming much more common worldwide. In the mid-1990s, CT scanning accounted for about 4% of procedures and about 40% of the collective dose in diagnostic radiology. With the advent of helical, fluoroscopic, and multi-slice techniques the dose per procedure has not diminished and the use of CT has increased even more. In large hospitals, CT scanning now accounts for about 15% of procedures and 75% of the diagnostic radiation dose received by patients. When multiple CT scans are conducted on the same patient, the absorbed doses are in the range at which small but statistically significant increases in cancer have been found in the atomic bomb survivors.

Adolescent↗
PubMed2002

Radiation injuries after fluoroscopic procedures.

Fluoroscopically guided diagnostic and interventional procedures have become much more commonplace over the last decade. Current fluoroscopes are easily capable of producing dose rates in the range of 0.2 Gy (20 rads) per minute. The dose rate often changes dramatically with patient positioning and size. Most machines currently in use have no method to display approximate patient dose other than the rough surrogate of total fluoroscopy time. This does not include patient dose incurred during fluorography (serial imaging or cine runs), which can be considerably greater than dose during fluoroscopy. There have been over 100 cases of documented radiation skin and underlying tissue injury, a large portion of which resulted in dermal necrosis. The true number of injuries is undoubtedly much higher. The highest dose procedures are complex interventions such as those involving percutaneous angioplasties, stent placements, embolizations, and TIPS. In some cases skin doses have been in excess of 60 Gy (6000 rads). In many instances the procedures have been performed by physicians with little training in radiation effects, little appreciation of the radiation injuries that are possible or the strategies that could have been used to reduce both patient and staff doses. Almost all of the severe injuries that have occurred were avoidable.

Eye↗