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Radiation Dose in CT Scans Varies Due to Scanners' Technical Settings

UCSF-led International Research Team Recommends Standard Protocols for CT Scan Doses

By Elizabeth Fernandez | UCSF.edu | January 8, 2019

Radiation Dose in CT Scans Varies Due to Scanners' Technical Settings

The amount of radiation that patients are exposed to from computed tomography (CT) scans varies widely between institutions and countries, and is largely due to differences in the technical settings of the scanning machines at each institution, according to an international study led by UC San Francisco.

The authors recommend that consistent international standards be established for optimizing doses without sacrificing accuracy.

The study appears in the British medical publication The BMJ

“Radiation, including radiation from CT, has been shown to be associated with an increased risk of cancer. Therefore, it is important to minimize exposures whenever possible,” said lead author Rebecca Smith-Bindman, MD, a UCSF professor of radiology, epidemiology and biostatistics, and of obstetrics, gynecology and reproductive medicine. “Our study indicates that this can be accomplished through the creation and implementation of consistent international technical standards for CT scanners.” 

For such standards to be established, she said, “we need to learn how institutions set up their scanning protocols in the first place, and how to develop consensus about balancing image quality with diagnostic accuracy.” 

The study used data collected from the UCSF CT International Dose Registry between November 2015 and August 2017. The researchers analyzed records of more than 2 million diagnostic CT scans conducted on 1.7 million adults in 151 institutions across seven countries (Switzerland, Netherlands, Germany, United Kingdom, United States, Israel and Japan). The records included scans of the head, abdomen, chest, and combined abdomen and chest.

The researchers controlled for variables including anatomical area scanned, patient characteristics, make and model of CT scanner, type of institution, and the scanners’ technical settings. They found that dose variations persisted even when patients were scanned on the same make and model of CT scanner or  were scanned for the same clinical reason, and even after adjusting for factors such as patient size. 

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