Unneeded CT Scans Magnify Radiation Risks

CHICAGO — Patients undergoing abdominal/pelvic computed tomography frequently receive unindicated additional scans, resulting in excess radiation exposure, a review of 978 CT scans suggests.

The review, which included exams done in 500 patients, revealed that 263 exams (52.6% of the total) were not indicated based on American College of Radiology Appropriateness Criteria. The exams, performed at institutions in Illinois, Michigan, Minnesota, and Wisconsin, involved patients aged 9 months to 91 years.

One in five patients received at least 50 millisieverts (mSv) of radiation in a single examination. Seven (1.4%) of the 500 patients received greater than 100 mSv—a dose that is associated with an increased cancer risk. The mean radiation dose per patient was 32.9 mSv, which is equivalent to the dose from about 1,000 chest X-rays. The 308 exams that consisted of multiple phases exposed patients to a mean dose of 43 mSv, Dr. Kristie Guite reported at the annual meeting of the Radiological Society of North America.

Radiologists are encouraged to follow the standard of “As Low as Reasonably Achievable” or ALARA, noted Dr. Guite, a resident at the University of Wisconsin, Madison. “The most important finding in this study is that adherence to ALARA is not widespread at this time,” she said at a press briefing during the meeting.

“At the doses seen in our study, 1 in 1,000 patients could get a radiation-induced cancer,” she said. If the data are extrapolated to all CT scans of the abdomen/pelvis performed in the United States, “this would lead to 23,000 radiation-induced cancer cases per year.”

As for why radiologists may order extra scans, coauthor Dr. J. Louis Hinshaw, also with the UW-Madison, said it may be that radiologists simply have the ability and tools available to perform the tests. Also, protocols are set up on CT scanners beforehand and are often designed to answer “what if” scenarios, in which additional views may be needed. “There is some risk-aversion that comes into play,” he said at the briefing.

Of the 500 patients, 7% had findings that would not have been identified without the extra scans, but most of these were not clinically relevant, Dr. Hinshaw said.

The Radiological Society of North America has partnered with the American College of Radiology to create a task force on adult radiation protection to increase awareness of cumulative dose and radiation risks.

Both researchers stressed that CT is a valuable diagnostic tool and that the study findings should not impede use of the technology.

Press briefing moderator Dr. Robert Zimmerman, professor of radiology at Weill Cornell Medical College in New York, concurred. He suggested that patients investigate the radiation protocol at their institution and ask their physicians what steps are being taken to minimize radiation dose.

“We don't want to damage patients, but we know we have the technology that is very useful in saving people's lives,” Dr. Zimmerman said. “We are trying to balance the two.”

In the current study, patients with a malignancy were 22% more likely to receive excess radiation, Dr. Guite said.

Delayed-phase imaging, performed after a contrast agent has accumulated in the kidneys/bladder, accounted for 77% of the unnecessary scans.

There was no study sponsorship, but one coauthor disclosed being a stock holder with NeuWave Medical Inc. and a patent holder with Covidien AG.

'At the doses seen in our study, 1 in 1,000 patients could get a radiation-induced cancer.'

Source DR. GUITE

CHICAGO — Patients undergoing abdominal/pelvic computed tomography frequently receive unindicated additional scans, resulting in excess radiation exposure, a review of 978 CT scans suggests.

The review, which included exams done in 500 patients, revealed that 263 exams (52.6% of the total) were not indicated based on American College of Radiology Appropriateness Criteria. The exams, performed at institutions in Illinois, Michigan, Minnesota, and Wisconsin, involved patients aged 9 months to 91 years.

One in five patients received at least 50 millisieverts (mSv) of radiation in a single examination. Seven (1.4%) of the 500 patients received greater than 100 mSv—a dose that is associated with an increased cancer risk. The mean radiation dose per patient was 32.9 mSv, which is equivalent to the dose from about 1,000 chest X-rays. The 308 exams that consisted of multiple phases exposed patients to a mean dose of 43 mSv, Dr. Kristie Guite reported at the annual meeting of the Radiological Society of North America.

Radiologists are encouraged to follow the standard of “As Low as Reasonably Achievable” or ALARA, noted Dr. Guite, a resident at the University of Wisconsin, Madison. “The most important finding in this study is that adherence to ALARA is not widespread at this time,” she said at a press briefing during the meeting.

“At the doses seen in our study, 1 in 1,000 patients could get a radiation-induced cancer,” she said. If the data are extrapolated to all CT scans of the abdomen/pelvis performed in the United States, “this would lead to 23,000 radiation-induced cancer cases per year.”

As for why radiologists may order extra scans, coauthor Dr. J. Louis Hinshaw, also with the UW-Madison, said it may be that radiologists simply have the ability and tools available to perform the tests. Also, protocols are set up on CT scanners beforehand and are often designed to answer “what if” scenarios, in which additional views may be needed. “There is some risk-aversion that comes into play,” he said at the briefing.

Of the 500 patients, 7% had findings that would not have been identified without the extra scans, but most of these were not clinically relevant, Dr. Hinshaw said.

The Radiological Society of North America has partnered with the American College of Radiology to create a task force on adult radiation protection to increase awareness of cumulative dose and radiation risks.

Both researchers stressed that CT is a valuable diagnostic tool and that the study findings should not impede use of the technology.

Press briefing moderator Dr. Robert Zimmerman, professor of radiology at Weill Cornell Medical College in New York, concurred. He suggested that patients investigate the radiation protocol at their institution and ask their physicians what steps are being taken to minimize radiation dose.

“We don't want to damage patients, but we know we have the technology that is very useful in saving people's lives,” Dr. Zimmerman said. “We are trying to balance the two.”

In the current study, patients with a malignancy were 22% more likely to receive excess radiation, Dr. Guite said.

Delayed-phase imaging, performed after a contrast agent has accumulated in the kidneys/bladder, accounted for 77% of the unnecessary scans.

There was no study sponsorship, but one coauthor disclosed being a stock holder with NeuWave Medical Inc. and a patent holder with Covidien AG.

'At the doses seen in our study, 1 in 1,000 patients could get a radiation-induced cancer.'

Source DR. GUITE

CHICAGO — Patients undergoing abdominal/pelvic computed tomography frequently receive unindicated additional scans, resulting in excess radiation exposure, a review of 978 CT scans suggests.

The review, which included exams done in 500 patients, revealed that 263 exams (52.6% of the total) were not indicated based on American College of Radiology Appropriateness Criteria. The exams, performed at institutions in Illinois, Michigan, Minnesota, and Wisconsin, involved patients aged 9 months to 91 years.

One in five patients received at least 50 millisieverts (mSv) of radiation in a single examination. Seven (1.4%) of the 500 patients received greater than 100 mSv—a dose that is associated with an increased cancer risk. The mean radiation dose per patient was 32.9 mSv, which is equivalent to the dose from about 1,000 chest X-rays. The 308 exams that consisted of multiple phases exposed patients to a mean dose of 43 mSv, Dr. Kristie Guite reported at the annual meeting of the Radiological Society of North America.

Radiologists are encouraged to follow the standard of “As Low as Reasonably Achievable” or ALARA, noted Dr. Guite, a resident at the University of Wisconsin, Madison. “The most important finding in this study is that adherence to ALARA is not widespread at this time,” she said at a press briefing during the meeting.

“At the doses seen in our study, 1 in 1,000 patients could get a radiation-induced cancer,” she said. If the data are extrapolated to all CT scans of the abdomen/pelvis performed in the United States, “this would lead to 23,000 radiation-induced cancer cases per year.”

As for why radiologists may order extra scans, coauthor Dr. J. Louis Hinshaw, also with the UW-Madison, said it may be that radiologists simply have the ability and tools available to perform the tests. Also, protocols are set up on CT scanners beforehand and are often designed to answer “what if” scenarios, in which additional views may be needed. “There is some risk-aversion that comes into play,” he said at the briefing.

Of the 500 patients, 7% had findings that would not have been identified without the extra scans, but most of these were not clinically relevant, Dr. Hinshaw said.

The Radiological Society of North America has partnered with the American College of Radiology to create a task force on adult radiation protection to increase awareness of cumulative dose and radiation risks.

Both researchers stressed that CT is a valuable diagnostic tool and that the study findings should not impede use of the technology.

Press briefing moderator Dr. Robert Zimmerman, professor of radiology at Weill Cornell Medical College in New York, concurred. He suggested that patients investigate the radiation protocol at their institution and ask their physicians what steps are being taken to minimize radiation dose.

“We don't want to damage patients, but we know we have the technology that is very useful in saving people's lives,” Dr. Zimmerman said. “We are trying to balance the two.”

In the current study, patients with a malignancy were 22% more likely to receive excess radiation, Dr. Guite said.

Delayed-phase imaging, performed after a contrast agent has accumulated in the kidneys/bladder, accounted for 77% of the unnecessary scans.

There was no study sponsorship, but one coauthor disclosed being a stock holder with NeuWave Medical Inc. and a patent holder with Covidien AG.

'At the doses seen in our study, 1 in 1,000 patients could get a radiation-induced cancer.'

Source DR. GUITE