Radiation Dose Tracking Software and Patient Safety

Reducing patient exposure to ionizing radiation continues to be a hot topic in radiology. Many imaging facilities implement dose monitoring software (DMS) to track radiation dose and help mitigate the risk of exposing patients to unnecessary radiation.

Applied Radiology hosted a recent webinar sponsored by Guerbet and presented by Samuel Brady, PhD, a clinical medical physicist and associate professor of radiology at Cincinnati Children's and University of Cincinnati in Ohio. Dr Brady develops and maintains CT protocols and dose minimization techniques, which are particularly important for the pediatric population at Cincinnati Children's.

Creating a Culture of Safety

Before DMS solutions began emerging in the past two decades, radiation dose was often not tracked by facilities. Clinicians typically had to manually calculate dose based on scanner data. Today's DMS can track dose metrics across modalities, going beyond earlier versions that reported only CT radiation exposure.

DMS helps to reduce patient risk by identifying inconsistent practices, poorly optimized examinations and procedures, devices that exceed radiation exposure levels, and the need for staff training.

“I truly love the fact that these software options are out there. These tools help answer the question of how we can image our patients better,” said Dr Brady.

Dr. Brady uses Guerbet’s Dose&Care® to help create a culture of safety. Many DMS solutions such as Dose&Care® track and present critical data, such as patient demographics, the number of studies performed over time, alert levels, protocols, and technologist performance, to help identify trends and challenges. “As someone that leads the dose tracking program at our hospital, this is very important. Now I'm able to look at the statistics of each protocol to establish alert levels,” he said.

In addition, DMS can help facilities generate feedback to guide radiologists and their staff. “DMS can actually demonstrate teaching points so they can learn from what's happened in the past so we can hopefully not repeat that,” he said.

Establishing Alert Levels

In Dr Brady’s view, dose tracking software is only as good as how it’s set up and implemented. “Paying attention to the details, especially when you initially set up the system, really pays dividends,” he said. “But once you get [the alert levels set for each modality and type of exam], they are largely self-sufficient in the background, and you just have to tweak them as new procedures or machines get installed in your system. Take the time upfront to do it right, and it will help you long term.”

There are several layers of warning or alerts that should be set up to help minimize patient risk, each layer is critically important. A common example of these three layers is found when discussing CT.  In CT, the first layer is called a Notification Value (NV) and it provides a warning system at the time of imaging to pause the initiation of a study if any of the imaging parameters will cause a dose level to exceed the NV; this is meant to prevent harm to the patient before the study begins. The second layer is called an Alert Value (AV), this occurs after imaging has been initiated and will cause a pause in the imaging, if the accumulating dose exceeds the AV threshold;  this is meant to prevent harm to the patient after a study has begun. 

The use of NVs and AVs stems from NEMA standard XR-25, which requires CT scanners to produce alerts to inform operators at the time of the study; typically, NVs are based on institution-specific dosing history.

Alert values, meanwhile, represent “never events” and are established at higher values than those for normal clinical procedures.

“We should never be crossing an AV. It’s the ultimate safety net to prevent patient harm,” said Dr Brady. “Setting up AV is meant to reduce risk from unnecessary exposure to ionizing radiation where we know that the risk-to-benefit ratio is not tilted towards the benefit side.”

Finally, the third layer is called an alert level, and it enables a warning system after the completion of a patient study, as monitored by the DMS; alert levels may be used to help reduce harm to future patients.

There are different types of alert levels, the first is known as a fixed value level. This is established and published by accreditation bodies and professional organizations such as the American College of Radiology and the American Association of Physicists in Medicine. A common type of fixed value is the diagnostic reference level (DRL), which is based on national databases. DRLs can be used to compare local institutional data to large sources of nationally derived data. “[DRLs] These are published data based on … hundreds of thousands of data points that we can use to develop a similar fixed value. So, we are able to say that we're comparing ourselves to national peers,” Dr Brady said.

He stressed that every facility must choose how to apply these fixed values. “When applying national DRL values, you need to consider how your system can interface with them,” he said. “You might have to calibrate your data or the patient demographic to set up your alert levels according to DRLs. Sometimes it takes a little bit of extra work to apply national DRLs in your DMS.”

A second type of alert level is based on a percent value, which can affect how often staff receive notifications from the DMS. “Percent values are based off your internal data. The question to ask is: how often do you want to respond to an alert?” he noted.

For example, at an institution that scans 500,000 patients a year with a 1% alert threshold, about 5,000 cases a year would trigger an alert, and approximately 500 [of those] studies would need to be reviewed every month. “That’s a lot,” said Dr Brady. “When we went through this process at Cincinnati Children’s, we had to set up two different levels of alerts in the DMS.”

To learn more about establishing alerts in DMS, view the entire Expert Forum.