Younger Patients Face Double Radiation Risk from CT Scans: Study
Younger patients run a higher risk of health problems from radiation exposure caused by computed tomography (CT) scans, according to a new study.
Researchers at the Medical University of South Carolina found that the radiation risk for younger patients were double those of older patients in a CT radiation exposure study presented last week at the American Roentgen Ray Society 2010 annual meeting in San Diego, CA. Scientists say that the findings indicate that age is another factor that doctors should consider when ordering CT scans.
Researchers looked at 51 patients who received pelvic and abdominal scans. They found that the estimated radiation risk for a 31 year old patient was 0.91 per every 1,000; twice that of the risk for a 74-year-old patient, 0.47 per 1,000. The risk for females was slightly higher than for males; 0.74 per 1,000, compared to 0.61 per 1,000.
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Learn More“Knowing the risk involved with radiation exposure to a patient during an abdominal/pelvic CT allows for more accurate risk benefit evaluation when a physician is deciding whether or not to order an exam,” said Dr. James Koonce, lead author of the study
CT scan procedures across the country are under close scrutiny by the FDA after the discovery that a number of patients have suffered radiation overexposure from CT Scans performed incorrectly. The FDA is currently reviewing CT scan procedures nationwide, and released interim guidance for health care professionals and radiologists in December. The guidance advised them to review procedures and CT scan settings, and to be thorough in checking the amount of dosage prescribed for each CT scan patient.
The recent FDA investigation was sparked by the discovery of CT scan radiation over-exposure problems that may have affected more than 200 patients at Cedars-Sinai Medical Center in Los Angeles last year. Since then, the FDA has uncovered at least 50 more radiation CT errors.
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ValderirOctober 1, 2012 at 9:36 pm
First, thank you for your reply, and also what a good question.“As a ditinosagc radiographer I am sorry but I have limited experience of the amazing work of the therapeutic discipline. Can you provide additional insight and benefits to the patient of preforming portal images with a single exposure? Good luck in the competition.”Let me see if I can help explain why my submission is so important. T[Show More]First, thank you for your reply, and also what a good question.“As a ditinosagc radiographer I am sorry but I have limited experience of the amazing work of the therapeutic discipline. Can you provide additional insight and benefits to the patient of preforming portal images with a single exposure? Good luck in the competition.”Let me see if I can help explain why my submission is so important. To help you better understand this work allow me to give some background.Portal images are taken to verify placement of the isocenter and that the intended area of treatment is indeed being irradiated. Typically when portal images are taken they are produced by the LINAC with MV radiation. Obviously you know we don’t use a mix of kVp and mAS. The exposure for a portal image is determined by what is called a monitor unit. A monitor unit is a measure of machine output. Typically LINACs are calibrated to deliver 1 cGy/ MU to a depth of dose maximum with a 10 cm x 10 cm field at an SSD of 100 cm. The typical portal image utilizes two exposures. One exposure is made of the treatment field size. The other is produced with the collimators open for the purpose of showing more anatomy. The required MUs for the combination of these exposures are in the neighborhood of 8 MUs. Now if the patient is ported weekly the cumulative dose is probably negligible, but with IGRT the patient is imaged daily. For example, an intact prostate patient with gold fiducial markers imbedded in his prostate would require a daily AP and a Lat portal image. This orthogonal pair allows a 3D correction if needs be. If the double exposure method is utilized the images produced daily would be four and the total per course of treatment would be 168. Now to give you some perspective on what the consequences of the double exposure are. The dose to the iso depth from the portal images would be less than the MU because of tissue attenuation. Typically the isocenter would receive 3 cGy per exposure. So the total dose from portal imaging would be approximately 504 cGy, which equals 54,000 chest x-rays! Yes that’s right, 54,000. So because of the need for only one exposure we can half that dose to 252 cGy instead of 504 cGy. I hope this offers an explanation.Thank you.