Radiation risk

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Radiation risk

Doctors concerned about the exploding use of CT scanners

Email|Print| Text size – + By Liz Kowalczyk

Globe Staff / November 26, 2007

Dr. David Bor, chief of medicine at the Cambridge Health Alliance, had been concerned for years about the financial cost of the rampant use of CT scans. But several months ago, after a conversation with the system's head of radiology, he started to worry about another kind of cost: radiation exposure to patients.

more stories like thisBor sent a memo to 150 doctors in his department in June, warning them about overreliance on CT scans and about the potential risk to patients; he recently invited in a radiation specialist to educate physicians; and he has altered his medical practice. Bor said, for example, that he no longer automatically orders a CT scan to diagnose abdominal pain in a patient with previous bouts of kidney stones.

"I am much more likely to suggest they have an ultrasound," which is harder to interpret but does not emit radiation, he said. "I'm much more vigilant about it now."

The use of CT, or computed tomography, is soaring. The number of scans performed on patients nationwide grew from 20 million in 1995 to 35 million in 2000 to 63 million in 2005. The rise has been fueled by improvements in the technology that give doctors clearer, more detailed pictures of the body, making CT an invaluable diagnostic test.

Companies are coming out with faster scanners that take more comprehensive pictures - Brigham and Women's Hospital recently bought one of the first 256-slice scanners in the world, which can take a picture of the entire heart and surrounding blood vessels in seconds.

And doctors and hospitals are using CT scans to diagnose patients complaining of headaches, abdominal pain, chest pain, and to monitor cancer patients for their response to drugs and for recurrence after treatment.

Early data show that a CT scan of the colon may be as effective as a colonoscopy for finding polyps that could lead to colon cancer - and if these results are borne out, tens of thousands more people could get regular CT scans. Researchers also are studying the effectiveness of CT scans in screening smokers and former smokers for lung cancer.

But some physicians are starting to sound alarm bells about radiation exposure from the expanding use of CT scanning, which uses multiple X-rays to create cross-sectional pictures of the organs and blood vessels. They are adopting practices to reduce the number of patients scanned and the number getting repeat scans.

A chest CT, for example, exposes a patient to about 8 millisieverts of radiation - 80 to 400 times the radiation exposure from a chest X-ray and, recent studies show, close to the lowest doses received by Japanese survivors of the atomic bombs who were farthest away from the blasts. These survivors, irradiated with 5 to 20 millisieverts, have demonstrated a small but measurable increase in their lifetime risk of dying from cancer. A person typically is exposed to 3 to 5 millisieverts a year from normal environmental sources.Continued...

"The scanners . . . are humming nonstop," said Dr. James Brink, chairman of diagnostic radiology at the Yale University School of Medicine and a member of the National Council on Radiation Protection and Measurements, a group charted by Congress to make safety recommendations. "It's one of the most valuable tools we have in medicine. There are innumerable diagnoses made and excluded by this technology on a minute-by-minute basis."

But, he said, "a larger and larger chunk of the population is being exposed to radiation because of the scans."

Brink said he is most concerned about patients, such as those with chronic kidney stones or Crohn's disease, who are scanned "over and over and over again." Younger patients are at higher risk than elderly patients, because they have more years to develop radiation-related cancer, which can take decades to appear.

Many cancer patients also receive repeated CT scans, especially those who are enrolled in clinical drug trials. Drug-makers or doctors may require scans every three months so they know as quickly as possible whether a medication is shrinking a patient's tumor or not. The benefit of CT scans to patients with life-threatening cancer can be far greater than to patients with other chronic diseases, so doctors generally are willing to give higher cumulative doses.

Brink lectures to doctors across the country about the importance of reducing unnecessary CT scans, and about ways to cut down radiation doses for patients who need scans. The more radiation the better the image - much like the comparison between high-definition television and conventional television - but doctors might not need a beautiful picture to make an accurate diagnosis, and alternative types of scans might work as well for some conditions. At Yale-New Haven Hospital, doctors now give a pregnant patients with lower right-side pain an MRI - which does not emit radiation - rather than a CT scan to diagnose appendicitis.

Other hospitals are taking precautions too.

Brigham and Women's is reprogramming its electronic medical record system to calculate and record a patient's dose for every procedure he or she receives that involves radiation, so doctors and patients will have a record over time. "The cumulative dose is as important as the individual dose," said Dr. Steven Seltzer, chairman of radiology.

Earlier this year, the American College of Radiology published a report on medical radiation, saying that the rapid growth of CT scans and nuclear medicine studies "may result in an increased incidence of radiation-related exposure in the not-too-distant future." The authors recommended an education campaign for patients, better state regulation to protect patients, and that insurers identify and alert the doctors of members who have had frequent CT scans.

Other doctors, especially those who treat patients with life-threatening cancer, said it's important for patients to keep the risk in perspective.

Modern scanners are much more efficient, allowing doctors to lower the radiation dose for smaller patients, and for pictures of thinner parts of the body, such as the front of the chest to the back, that don't require as much radiation as a side-to-side view. And manufacturers are developing CT scanners that produce less radiation overall.

Jeffrey Yap, senior diagnostic physicist at Dana-Farber Cancer Institute, said he considers it a positive sign if a patient has gotten multiple CT scans, because it means the patient has survived long enough to require continued monitoring. He said doctors at the hospital carefully calculate how much radiation patients would be exposed to before enrolling them in a clinical trial, although he said there is no absolute maximum that applies to all patients.

No studies have been done connecting multiple CT scans to cancer, and it would be difficult to conduct such research, for ethical reasons and because of how long it takes radiation-related cancer to develop. So doctors must make assumptions based on large-scale accidents or events such as the dropping of the atom bombs on Japan.

"Frankly a lot of the US has not been on top of the radiation issue partly because the data is not that good," said Dr. Giles Boland, vice chairman for business development for the radiology department at Massachusetts General Hospital.

But Bor, the Cambridge Health Alliance medicine chief, said in the absence of data on cumulative risk, doctors need to be thoughtful about CT use. He wonders whether doctors should adopt policies requiring a detailed discussion of risks and benefits for patients who've received repeat CT scans, much like the "informed consent" process for surgery and blood transfusions. "Everyone is rushing to buy the machines, yet the data to tell us how to use them for our patients really isn't there," he said.

"The scanners . . . are humming nonstop," said Dr. James Brink, chairman of diagnostic radiology at the Yale University School of Medicine and a member of the National Council on Radiation Protection and Measurements, a group charted by Congress to make safety recommendations. "It's one of the most valuable tools we have in medicine. There are innumerable diagnoses made and excluded by this technology on a minute-by-minute basis."

more stories like thisBut, he said, "a larger and larger chunk of the population is being exposed to radiation because of the scans."

Brink said he is most concerned about patients, such as those with chronic kidney stones or Crohn's disease, who are scanned "over and over and over again." Younger patients are at higher risk than elderly patients, because they have more years to develop radiation-related cancer, which can take decades to appear.

Many cancer patients also receive repeated CT scans, especially those who are enrolled in clinical drug trials. Drug-makers or doctors may require scans every three months so they know as quickly as possible whether a medication is shrinking a patient's tumor or not. The benefit of CT scans to patients with life-threatening cancer can be far greater than to patients with other chronic diseases, so doctors generally are willing to give higher cumulative doses.

Brink lectures to doctors across the country about the importance of reducing unnecessary CT scans, and about ways to cut down radiation doses for patients who need scans. The more radiation the better the image - much like the comparison between high-definition television and conventional television - but doctors might not need a beautiful picture to make an accurate diagnosis, and alternative types of scans might work as well for some conditions. At Yale-New Haven Hospital, doctors now give a pregnant patients with lower right-side pain an MRI - which does not emit radiation - rather than a CT scan to diagnose appendicitis.

Other hospitals are taking precautions too.

Brigham and Women's is reprogramming its electronic medical record system to calculate and record a patient's dose for every procedure he or she receives that involves radiation, so doctors and patients will have a record over time. "The cumulative dose is as important as the individual dose," said Dr. Steven Seltzer, chairman of radiology.

Earlier this year, the American College of Radiology published a report on medical radiation, saying that the rapid growth of CT scans and nuclear medicine studies "may result in an increased incidence of radiation-related exposure in the not-too-distant future." The authors recommended an education campaign for patients, better state regulation to protect patients, and that insurers identify and alert the doctors of members who have had frequent CT scans.

Other doctors, especially those who treat patients with life-threatening cancer, said it's important for patients to keep the risk in perspective.

Modern scanners are much more efficient, allowing doctors to lower the radiation dose for smaller patients, and for pictures of thinner parts of the body, such as the front of the chest to the back, that don't require as much radiation as a side-to-side view. And manufacturers are developing CT scanners that produce less radiation overall.

Jeffrey Yap, senior diagnostic physicist at Dana-Farber Cancer Institute, said he considers it a positive sign if a patient has gotten multiple CT scans, because it means the patient has survived long enough to require continued monitoring. He said doctors at the hospital carefully calculate how much radiation patients would be exposed to before enrolling them in a clinical trial, although he said there is no absolute maximum that applies to all patients.

No studies have been done connecting multiple CT scans to cancer, and it would be difficult to conduct such research, for ethical reasons and because of how long it takes radiation-related cancer to develop. So doctors must make assumptions based on large-scale accidents or events such as the dropping of the atom bombs on Japan.

"Frankly a lot of the US has not been on top of the radiation issue partly because the data is not that good," said Dr. Giles Boland, vice chairman for business development for the radiology department at Massachusetts General Hospital.

But Bor, the Cambridge Health Alliance medicine chief, said in the absence of data on cumulative risk, doctors need to be thoughtful about CT use. He wonders whether doctors should adopt policies requiring a detailed discussion of risks and benefits for patients who've received repeat CT scans, much like the "informed consent" process for surgery and blood transfusions. "Everyone is rushing to buy the machines, yet the data to tell us how to use them for our patients really isn't there," he said.

© Copyright 2007 Globe Newspaper Company.