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Using text to make CT scans safer

Toronto, July 18, 2014

By Greg Winson

Dr. Bruce Gray stands in front of a CT scanner
Dr. Bruce Gray stands in front of a CT scanner. (Photo by Yuri Markarov)

Computed tomography, or CT, scans represent an important advancement in medical care, allowing doctors to non-invasively view detailed images of the body. However, since these diagnostic tests require the use of radiation, it is important to monitor whether the scans are necessary and that they use a radiation dose that is as low as reasonably achievable.

Dr. Bruce Gray and Dr. Timothy Dowdell, radiologists in the Medical Imaging Department at St. Michael’s Hospital, hope to use image metadata—basically data about data--that is attached to each CT study to ensure that the process is safe and effective.

“Image metadata, similar to metadata for images in a digital camera, contains information on the type of CT scanner, type of study, who ordered it, when it was performed, by whom and the specific scanner settings used for the particular study,” said Dr. Gray.

Little was done with this metadata until a Toronto-based company, Radimetrics, developed software to extract the information into a database for analysis. St. Michael’s was an early adopter of this dose-tracking software and now has a database containing metadata from St. Michael’s CT scans for the past four years. This has allowed for the development of a quality initiative that has seen radiation exposures for routine scans going down during this period.

During the last 18 months, Drs. Gray and Dowdell have been working to expand this approach to data collection and analysis province-wide with the creation of the Medical Imaging Metadata Radiation Registry of Ontario, or MIMRRO.


Did you know?
- St. Michael’s performs 35,000 CT scans per year
- St. Michael’s has three CT scanners

By analyzing the CT radiation data across institutions they will be able to determine the average radiation exposure for particular exams and identify centres that may be using more than necessary.

“The fact that there are wide variations in radiation dose between sites is a concern,” said Dr. Gray. “Reducing average dose as well as identifying causes of variability and reducing them will significantly improve the care to our patients.”

MIMRRO is focused on data from CT scans but ultimately could be applied to other types of medical imaging, such as interventional radiology, nuclear medicine and MRI.

About St. Michael's Hospital

St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in 27 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael's Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.