Evaluating Kidney Stones – Why Use Reduced-Dose CT Scans

by | Aug 3, 2021 | CT

Reading Time: 3 minutes

According to the National Health and Nutrition Examination Survey, there is an upward trend in the prevalence of kidney stones in the United States. In a cross-sectional analysis of data from 2007 to 2010, researchers found an average prevalence of 8.8 percent—10.6 percent among men and 7.1 percent among women.

There are many reasons why people form kidney stones. Some causes include too little or too much exercise, drinking too little water, or eating food with too much sugar or salt. Obesity, weight loss surgery, and infections, or family history might also be factors in some situations. Fortunately, proper screening and care can facilitate treatments for this condition.


Reduced-Dose CT for Evaluating Kidney Stones

An effective way of evaluating kidney stones is with a CT scan with reduced radiation. Reduced-dose CT lessens the radiation burden on patients who have to undergo repeat sessions of imaging. However, reduced-dose CT isn’t as widely used as it should, according to a group of researchers at the Yale University School of Medicine. These researchers, led by Dr. Christopher Moore, wrote:

“Reduced dose CT use […] remains well below what is ‘as low as reasonably achievable […] Increased adoption of reduced-dose CT protocols will decrease the overall radiation burden associated with kidney stone CT, which often requires repeat imaging in relatively young patients.”


Findings from the Yale Research

Moore and his fellow researchers noted that kidney stones tend to affect younger people. It is a common and recurring condition, so overexposure to radiation is a genuine concern among people suffering from kidney stones. Of people afflicted with stones, Moore and his colleagues note that 85 percent undergo CT. These patients receive an average of 1.4 to 1.7 CT scans per incidence. These statistics highlight the need for radiation protocols.

The Yale researchers sought to use reduced doses of CT for people with kidney stones. They designed an intervention they named DOSE or Dose Optimization for Stone Evaluation. It includes continuing education, protocol recommendations, and consultations for patients and facilities. The team included 192 facilities in their study. These medical centers performed 422,039 CT scans for kidney stones between 2015 and 2019.

The researchers randomized half of the centers to an intervention cohort implementing DOSE protocols and kept the other half as a control group. The team further classified the intervention cohort into ‘having participated’ and ‘not having participated,’ which had 25 and 71 participants, respectively. 

Once they had their participants, the researchers tracked DLP or dose-length product changes from 2015 and compared these with data from 2017, 2018, and 2019. The researchers reported that between 2015 and 2017, the DLP fell by 16 percent in facilities that followed DOSE. They also noted that facilities using DOSE had a year-on-year increase in the proportion of reduced-dose CT scans. These findings prompted them to conclude that reduced-dose CT for kidney stone evaluation is feasible and sustainable. They wrote:

“It is the shared responsibility of medical users of … radiation dose-based imaging tests such as CT to ensure use of as low as reasonably achievable radiation doses. […] This is particularly true for an indication such as kidney stone CT, in which there is unequivocal evidence that [reduced dose] can be employed without adverse effects.”



Kidney stone treatment often involves CT scans, and the amount of scans needed puts patients in danger of overexposure to radiation. Medical facilities would benefit from implementing protocols like DOSE, which strike a balance between patient health and accuracy.

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