Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Unindicated CT series result in unnecessary radiation exposure for patients

A large proportion of patients who undergo abdominal/pelvic computed tomography (CT) receive unindicated and unnecessary additional image acquisition resulting in excess, avoidable radiation exposure, according to a study presented today at the annual meeting of the Radiological Society of North America (RSNA).

"It is the responsibility of all physicians who work with ionizing radiation to ensure that the dosage is as low as reasonably achievable without compromising the patient's well being," said Kristie Guite, M.D., radiology resident at the University of Wisconsin (UW) in Madison. "Our study found that this principle is not being followed in many practices."

A CT examination consists of imaging the patient using a CT scanner and sometimes involves the injection of an intravenous contrast agent. Imaging can be performed at multiple time points before and/or after the injection of the contrast material. Each image acquisition is referred to as a "series." Although having multiple series can be helpful for some conditions, they are not generally necessary.

Because it provides valuable diagnostic information, CT use has risen rapidly. In recent years, a number of reports have highlighted the increasing radiation exposure to patients through the use of medical imaging, particularly CT. While these reports have often focused on general and screening uses, little attention has been paid to radiation from additional series, including routine non-contrast or delayed-phase CT, which may or may not be indicated by the patient's condition but are sometimes performed so that nothing is overlooked.

To determine the frequency of unindicated additional scanning and the resultant excess radiation exposure to patients, the researchers reviewed the appropriateness and radiation dose of abdomen and pelvis CT exams for 500 patients performed at outside institutions and submitted to UW – Madison for interpretation. The patients ranged in age from nine months to 91 years, with most between 30 and 50 years old.

There were a total of 978 series for the 500 patients. Using the American College of Radiology (ACR) Appropriateness Criteria®, 35.3 percent (345/978) of the CT series in 52.2 percent (261/500) of the patients were determined to be unindicated. The most common unnecessary exam was delayed-phase imaging, accounting for 268 (77.7 percent) of the 345 unnecessary series. In delayed-phase imaging, several images of the same region are obtained a short period of time after contrast injection to detect changes. Among the 500 patients, the mean excess radiation dose per patient from unnecessary scans was 11.3 millisieverts (mSv), equivalent to the dose received from 113 chest x-rays or three years of naturally occurring background radiation.

"We suspect that at many institutions there is a lack of focus on selecting CT protocols tailored specifically to answer the clinical question," said coauthor J. Louis Hinshaw, M.D., assistant professor of radiology at UW – Madison. "It is certainly easier to select an 'every size fits all' approach."

The researchers also noted a possible connection in some cases between additional scanning and increased payment, such as performing both non-contrast and contrast-enhanced scans when only one series was indicated.

Efforts are ongoing to protect patients from unnecessary radiation exposure from medical imaging procedures, including the Image Gently initiative for safety in pediatric radiology and an ACR-RSNA task force for adult radiation protection. In addition to following strict appropriate imaging utilization standards, radiologists and medical physicists stress the importance of minimizing dose without sacrificing diagnostic ability. Advances in CT technology over recent years have markedly decreased dose while maintaining optimal image quality.

Dr. Guite advises patients not to be unduly alarmed when their physician orders a CT exam.

"The use of CT has been a huge benefit to human health," she said. "When used appropriately, the benefits of the diagnostic information obtained with CT far outweigh the potential risks."

Dr. Hinshaw suggests that patients ask their physicians about the risks and benefits of the proposed exam and inquire at the CT facility as to the number of series that will be performed, and if a smaller number of series would be sufficient.

Coauthors are Frank N. Ranallo, Ph.D., and Fred T. Lee, M.D.

Note: Copies of RSNA 2009 news releases and electronic images will be available online at beginning Monday, Nov. 30.

RSNA is an association of more than 44,000 radiologists, radiation oncologists, medical physicists and related scientists committed to excellence in patient care through education and research. The Society is based in Oak Brook, Ill. (

Editor's note: The data in these releases may differ from those in the printed abstract and those actually presented at the meeting, as researchers continue to update their data right up until the meeting. To ensure you are using the most up-to-date information, please call the RSNA Newsroom at 1-312-949-3233.

Linda Brooks | EurekAlert!
Further information:

More articles from Medical Engineering:

nachricht Gentle sensors for diagnosing brain disorders
29.09.2016 | King Abdullah University of Science and Technology

nachricht New imaging technique in Alzheimer’s disease - opens up possibilities for new drug development
28.09.2016 | Lund University

All articles from Medical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>