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XaHP Document 111, October 2001
To help educate health professionals and the public about x-ray dose-levels, the X-Rays and Health Project has assembled some excerpts from the peer-reviewed radiology journal American Journal of Roentgenology. (Roentgen ray is another name for x-ray.) The AJR is edited by Lee F. Rogers, M.D. and published by the American Roentgen Ray Society (www.arrs.org), which was founded in 1900 -- the nation's first radiology society.
CT (Computed Tomography) Exams
Rogers 2001: "So the time has come for radiologists to make the effort to lower radiation exposure doses in CT for our patients . . . Why is radiation exposure in CT so high? Probably because we radiologists have not insisted that patient exposure doses be lowered. It is time for us to do so," writes Lee F. Rogers, M.D., Editor-in-Chief of AJR in his ground-breaking editorial in the August 2001 issue (AJR 177: p.277). Among his colleagues, Dr. Rogers personifies outstanding leadership.
Ravenel et al 2001: During CT exams, the dose to patients is proportional to the selected value for milliampere-seconds (mAs). Prof. James G. Ravenel (with colleagues in Radiology at SUNY Upstate Medical University, Syracuse, NY), led a study which concludes, "Radiographic techniques for unenhanced chest CT examinations can be reduced from 280 to 120 mAs without compromising image quality" (AJR 177: 279-284. August 2001). Ravenel and colleagues are studying the extent to which their findings are applicable to all types of chest CT studies.
Nickoloff + Alderson 2001: "Because of the high radiation exposure potential of present-day helical and multi-slice helical CT, radiologists should be aware of the radiation risks of CT and work actively to keep patient radiation exposures from CT as low as possible while achieving the required image quality and benefit (p.285) . . . Scanning techniques can be altered to provide acceptable images at lower radiation exposures (p.286) . . . We recommend that a qualified radiology physicist determine and post the estimated patient radiation doses for various CT scans in all CT working areas. This notification will serve to remind technologists and radiologists about judicious selection of scan parameters (p.287)" (Edward L. Nickoloff and Philip O. Alderson, Radiology Dept., Columbia University, NYC in AJR 177: 285-287. August 2001).
Haaga 2001: "One of the major imperatives of rational CT is to minimize the amount of radiation used to obtain diagnostic scans or to execute interventional procedures (p.289) . . . The need and ability to adjust milliampere-seconds and radiation dose to suit individual patient size is a no-brainer (p.289) " (John R. Haaga, Radiology Dept., University Hospitals of Cleveland, in AJR 177: 289-291. August 2001).
Fluoroscopes use x-ray beams which can irradiate patients continuously or in a pulsed fashion, during diagnosis and frequently in guiding catheters, biopsy needles, and other instruments. Modern machines have freeze-frame capability ("last-image hold"). Radiologists are not the only specialists using fluoroscopy ("fluoro"). Additional users include cardiologists, neurologists, urologists, gastro-enterologists, and others.
Rogers 2001: In his July 2001 editorial, AJR editor-in-chief Lee F. Rogers, M.D., focuses on reducing x-ray doses during fluoroscopy. He writes, "The operator must be aware of the amount of radiation used during a procedure. Cavalier attitudes about fluoro time, failure to record the time, and conscious avoidance of steps that minimize exposure are to be condemned and discouraged. Using intermittent fluoro, pulsed fluoro, simply taking your foot off the fluoro pedal, reviewing the previous run on video rather than repeating it -- there are many ways to reduce exposure without compromising a procedure, but you must recognize the need to do so . . . If you use radiation, you must respect it. You must be informed and believe. Radiation safety is serious business" (Lee F. Rogers, M.D., in AJR 177: p.1. July 2001).
Boland et al 2000: Dr. Boland and co-workers "evaluated the diagnostic accuracy of a grid-controlled fluoroscopy unit compared with a conventional continuous fluoroscopy unit for a variety of abdominal and pelvic fluoroscopic examinations . . . Our findings suggest that most abdominal and pelvic fluoroscopic procedures can be performed at substantially lower frame rates than those used for continuous fluoroscopy; adopting this procedure may lead to substantial dose savings for the patient and the fluoroscopy operator" (Giles W. L. Boland and 4 co-workers at the Massachusetts General Hospital in Boston, in AJR 175: 1453-1457. November 2000).
Suleiman 2001: Orhan Suleiman, Ph.D., is Exec. Secretary of the FDA's "Technical Electronic Product Radiation Safety Standards Committee." He is quoted in the September 2001 issue of ASRT Scanner (p.8): "Doses from fluoroscopy can easily be reduced by orders of magnitude [over 10-fold] when one uses currently available technologies such as a cumulative timer, pulsed fluoroscopy, more filtration, better collimation, last frame hold, dose and dose rate display." (In "Radiation Dose: The Elephant in the Radiology Department," by Robin Anderson, Managing editor of ASRT Scanner 33, No.12: 6-8, Sept. 2001. ASRT Scanner is the official member newsmagazine of the American Society of Radiologic Technologists (www.asrt.org), which was established in 1920 and currently has 90,000 members.)
Printed by the X-rays and Health Project (Document 111, October 2001), Committee for Nuclear Responsibility, Inc.