Optimizing CT Radiation Doses Across Institutions Leads to Dose Reductions

This excellent research from UCSF documents that education about best CT dose practices has a significant impact. The authors state, “The project strategy was to collectively define metrics, assess radiation doses, and move toward dose standardization. This article presents the results of our efforts using a combination of facility-level audit and collaborative efforts to share best practices.”


Low radiation dose without compromise of image quality

This article illustrates that Radiologists’ perceptions of image quality and content change as they become accustomed – over time –  to the different noise pattern of the various types of iterative reconstruction.

In fact, no spatial resolution or low contrast resolution is lost with iterative reconstruction techniques – and diagnostic power is maintained.

Our work here at UW Medicine agrees with this report.

And it is important to know this because iterative reconstruction can result in 30%-60% dose reduction for all types of CT, without loss of diagnostic power.

Emphysema Found on CT Scans Points to Increased Lung Cancer Risk

That there are strong associations between smoking and emphysema and smoking and lung cancer is well established. Therefore, it’s of little surprise that a report from Lung Cancer finds emphysema that is visible to radiologists from CT scans is correlated with an increased risk of lung cancer.

However, these results were only discovered when the emphysema was read by radiologists— and not by computer interpretation. Researchers point out that radiologists and automated computer software likely detect different types of emphysema- with only doctors appearing to detect the type of emphysema associated with lung cancer. This clearly highlights the “intuition” factor in scan interpretation by experienced radiologists—a factor not yet evident in intelligent computers!

Patients that are found to have emphysema detected by CT scans are already at an increased risk of developing lung cancer and should quit smoking as soon as possible. It is interesting to remember that before cigarette smoking became widespread, both lung cancer and emphysema were exceedingly rare diseases. Those high risk patients should explore the benefits of lung cancer screening and lung cancer screening programs.

For more information on the benefits of lung cancer screening, please see here.

Obesity and CT Scan Radiation—Technology Helps to Cut Exposure

Most medical equipment is not designed for obese patient optimization, including diagnostic imaging modalities. Due to this, overweight and obese individuals are subject to higher levels of radiation during routine CT scans and X-rays.

A recent study, published in the Journal of Physics in Medicine and Biology, calculated exactly how much additional radiation overweight patients are exposed to from CT scans. According to the research, obese men and women receive 62 percent and 59 percent more radiation during CT scans than normal weight individuals. However, new technology can help control that percentage.

Phantoms, realistic 3-D computer models of overweight and obese men and women, can now be used to determine the risk of radiation scans on different body types.  The use of various sized phantoms to study CT dose distribution within the human body is a very scientific approach when considering the effects of CT. This technology will be able to accurately tell radiologists how much radiation patients receive from different devices so that they can make the safest and optimal choice for the patient.

Notice, this article highlights the significant increase in radiation dose—especially in obese patients—from increasing kVp to 140. At UW, our technologists use 140 kVP for CT only after having a conversation with a radiologist about each specific case.

Learn more about the use of phantoms for obese patients here.

Face Time with Patients Helps Increase Low Dose Understanding

A recent article in Health Imaging discusses a study that caught my eye. According to the study, the article noted, 80 to 90 percent of radiologists remain “invisible to their patients and approximately half of the public is unaware of whether radiologists are physicians or technicians.” In effect, the “commoditization of radiology is becoming a pressing concern to many practitioners.”

The authors of this study provide a good solution: “By offering an even higher level of personalized service through direct communication, radiologists can dispel this viewpoint by showing patients that they customize imaging examinations to fit each patient’s individual healthcare needs.”

I find this relates to my own experiences as a radiologist and, in a way, to the low dose movement. One way to lower the dose of CT is to not do inappropriate CT scans. How do you decide what is inappropriate?

This is where the radiologist (a physician) as a knowledgeable advisor (who consults with other physicians about imaging) comes in.

Face time with patients can help them understand this role. It can also help them understand that lower dose in their appropriate CT exams is possible without compromising the diagnostic power of the exam – again, achieved through a knowledgeable radiologist designing the CT exam and monitoring the conduct of executing the exam.

Team Effort Needed in Push for Low Radiation Dose CT

In the days that followed last month’s Low Dose CT Symposium, I had time to reflect on how wonderful it was that the event drew an unprecedented number of attendees. The interest in the symposium was evident by how far some attendees traveled to get there. I was also struck by the segments of the industry that were represented in the audience: technologists, radiologists, technicians and administrators were all there. It made me think about each segment’s relationship to one another, and their ability to impact change in the industry.

When driving toward much lower radiation dose in CT, it’s good to remember that a team effort is needed. Technologists must be educated on all the tricks and skills needed and must fully understand why dose reduction is important. They can help radiologists be more conscious of dose exactly when radiologists are urging technologists to pay close attention. Both techs and radiologists can use their knowledge to help educate administrators about the importance of investing in low dose CT. Everyone can help educate referring clinicians about thinking of dose when they order, both for an individual study and cumulative dose (over time) in individual patients. And it is the whole chain of providers who monitor appropriateness of studies at each and every level.

ACR Guidelines Still Best Resource for Determining Appropriateness of CT Imaging

William R. Hendee, Medical College of Wisconsin, makes some very valid points in a recent article about overuse of CT scans and the harmful effects unnecessary exams have on both patients and the healthcare industry. Specifically, he says that radiologists can “play a big role in educating ordering physicians about what scans are appropriate and when.”

A big part of the training and experience-based learning of radiologists is what imaging tests are appropriate for specific healthcare problems and what imaging tests are inappropriate. Inappropriate means the imaging test has little chance of adding significant value to the diagnosis and therapy of the patient, especially relative to its cost.

The American College of Radiology (ACR) has spent more than a decade developing imaging appropriateness guidelines for hundreds of clinical problems and indications. These ACR appropriateness guidelines are based on the best available scientific evidence and were written by panels of best sub-specialized experts. The guidelines each get revised every three to five years as new evidence becomes available. There is no better source available for appropriateness of diagnostic imaging.

The decision support computer programs mentioned in the article start with the ACR appropriateness guidelines and create a quick way for referring physicians to know if any imaging test they order is appropriate. At the point of computerized imaging exam order entry into an electronic system, the decision support examines the entered indications for an imaging exam and then either agrees with doing the exam, or cautions that the exam may be only marginally indicated – or states that by generally accepted criteria the requested exam is unindicated. There is education involved, as the evidence-based reasons an exam is unindicated are provided to the ordering physician, along with suggestions for a better approach to the patient’s problem (often involving some other type of imaging). These decision support programs are now running in several healthcare enterprises, and they hold good hope for decreasing inappropriate complex imaging exam utilization without blocking access to appropriate tests.