Featured Research

from universities, journals, and other organizations

Numerous CT Scans Over Lifetime May Increase Cancer Risk

Date:
April 1, 2009
Source:
Radiological Society of North America
Summary:
Patients who undergo numerous CT scans over their lifetime may be at increased risk for cancer, according to a new study.

Patients who undergo numerous CT scans over their lifetime may be at increased risk for cancer, according to a new study.
Credit: iStockphoto/Brad Wieland

Patients who undergo numerous CT scans over their lifetime may be at increased risk for cancer, according to a new study.

"We found that while most patients accrue small cumulative cancer risks, 7 percent of the patients in our study had enough recurrent CT imaging to raise their estimated cancer risk by 1 percent or more above baseline levels," said Aaron Sodickson, M.D., Ph.D., assistant director of Emergency Radiology at Brigham and Women's Hospital and researcher at the Center for Evidence-Based Imaging in Boston. "The techniques implemented in our study can be used to identify higher risk patients who might benefit from enhanced radiation protection efforts."

CT has proven to be a valuable clinical tool, and its use has grown rapidly. According to a 2008 IMV Medical Information Division report, approximately 68.7 million CT exams were performed in the U.S. in 2007, up from 62 million in 2006. CT provides detailed images of internal organs and is a common technique used to make medical diagnoses and help guide medical treatment decisions. However, CT uses a higher radiation dose than most other imaging exams.

For the study, the researchers developed new methodology to estimate cumulative CT radiation doses and associated radiation-induced cancer risks at the level of the individual patient, by extracting each patient's CT history from the electronic medical record and applying standard risk-estimation models that incorporate patient gender and age at exposure.

The study group was comprised of 31,462 adult patients who had diagnostic CT scans at Brigham and Women's Hospital or the Dana-Farber Cancer Center in 2007 and had undergone a total of 190,712 CT exams over the prior 22 years. Approximately 33 percent of the patients underwent five or more lifetime CT exams, 5 percent underwent more than 22 exams, and 1 percent underwent more than 38 exams. Fifteen percent received estimated cumulative effective radiation doses of more than 100 millisieverts (mSv), equivalent to the dose one would receive from 1,000 chest x-rays. Four percent received over 250 mSv, and 1 percent received over 399 mSv.

The researchers used the BEIR-VII (Biological Effects of Ionizing Radiation) risk model to estimate lifetime attributable risk (LAR) of cancer for each patient, based on their CT exposures. Approximately 7.3 percent of the study group had an estimated LAR of greater than 1 percent, meaning that due to cumulative CT radiation exposure, their risk of developing cancer increased by 1 percent above the baseline US cancer risk rate of 42 percent. Among the 315 patients in the top percentile of cumulative LAR, risk increased by 2.7 to 12 percent.

"CT is an excellent diagnostic tool of tremendous clinical value in many situations," Dr. Sodickson said. "Individual decisions about its use should balance the expected clinical benefits against the potential cumulative risks of recurrent imaging."

Dr. Sodickson points out that for patients who have not undergone a large number of CT scans, the benefits of appropriate CT exams typically outweigh the potential risks.

"However, we feel that a higher clinical threshold is warranted in patients undergoing a large amount of recurrent CT imaging," Dr. Sodickson said, "particularly if many of their prior CT scans have been negative. This scenario may result in a combination of high cumulative risk with low clinical benefit."

Dr. Sodickson hopes that these findings will raise awareness of cumulative radiation exposure concerns, so that physicians will be better able to incorporate patient-specific radiation risk estimates into the CT decision-making process.


Story Source:

The above story is based on materials provided by Radiological Society of North America. Note: Materials may be edited for content and length.


Journal Reference:

  1. Sodickson et al. Recurrent CT, Cumulative Radiation Exposure, and Associated Radiation-induced Cancer Risks from CT of Adults. Radiology, 2009; 251 (1): 175 DOI: 10.1148/radiol.2511081296

Cite This Page:

Radiological Society of North America. "Numerous CT Scans Over Lifetime May Increase Cancer Risk." ScienceDaily. ScienceDaily, 1 April 2009. <www.sciencedaily.com/releases/2009/03/090331091244.htm>.
Radiological Society of North America. (2009, April 1). Numerous CT Scans Over Lifetime May Increase Cancer Risk. ScienceDaily. Retrieved September 19, 2014 from www.sciencedaily.com/releases/2009/03/090331091244.htm
Radiological Society of North America. "Numerous CT Scans Over Lifetime May Increase Cancer Risk." ScienceDaily. www.sciencedaily.com/releases/2009/03/090331091244.htm (accessed September 19, 2014).

Share This



More Health & Medicine News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Could Grief Affect The Immune Systems Of Senior Citizens?

Could Grief Affect The Immune Systems Of Senior Citizens?

Newsy (Sep. 19, 2014) The study found elderly people are much more likely to become susceptible to infection than younger adults going though a similar situation. Video provided by Newsy
Powered by NewsLook.com
Jury Delivers Verdict in Salmonella Trial

Jury Delivers Verdict in Salmonella Trial

AP (Sep. 19, 2014) A federal jury has convicted three people in connection with an outbreak of salmonella poisoning five years ago that sickened hundreds of people and was linked to a number of deaths. (Sept. 19) Video provided by AP
Powered by NewsLook.com
How The 'Angelina Jolie Effect' Increased Cancer Screenings

How The 'Angelina Jolie Effect' Increased Cancer Screenings

Newsy (Sep. 19, 2014) Angelina's Jolie's decision to undergo a preventative mastectomy in 2013 inspired many women to seek early screenings for the disease. Video provided by Newsy
Powered by NewsLook.com
The Cost of Ebola

The Cost of Ebola

Reuters - Business Video Online (Sep. 18, 2014) As Sierra Leone prepares for a three-day "lockdown" in its latest bid to stem the spread of Ebola, Ciara Lee looks at the financial implications of fighting the largest ever outbreak of the disease. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins