Using CT to Search for Urinary Tract Stones

CT to search for urinary tract stone is a very commonly performed procedure because both negative and positive results may have significant impact on subsequent patient care. Often the patients are younger since stones can occur at any age.

This article presents very encouraging news about significantly lowering the dose of a CT for urinary stones by using statistical iterative reconstruction – yet with acceptable image quality and no loss of diagnostic power.

This report adds to a rapidly growing body of data about both statistical iterative reconstruction and model based iterative reconstruction for various types of CT exams.  This body of data almost uniformly reports substantial patient radiation dose reduction in the 30% to 60% range with equal or even better image quality.

Analyzing the Cost-effectiveness of Low-dose CT

We already know that low-dose CT is a valuable tool for reducing mortality rates, but now there’s evidence that it might reduce financial costs as well. A new analysis of the 2010 National Lung Screening Trial (NLST) shows that low-dose CT is a cost-effective diagnostic tool for patients at high-risk of lung cancer, according to AuntMinnie.com.

The Medical Imaging and Technology Alliance (MITA) released a statement saying the organization welcomes the analysis and “looks forward to ongoing collaboration with patient advocates and others in the imaging community to ensure access to this lifesaving technology.”

In my opinion, though, the key question in whether low-dose screening for lung cancer is cost effective is: what is the cost of working up the false positives? That cost needs to be subtracted from the cost benefit of the lives saved. This new analysis suggests that low-dose screening is indeed cost effective. One thing no cost analysis considers: the value of a negative exam to a very worried patient.

Further new twist: we now can do ultra-low-dose lung cancer screening using fully model-based iterative reconstruction techniques. This technique enables a 60 percent radiation dose reduction (down to the sub-0.5 mSv range) below that of even recent low-dose CT – further substantially decreasing any downside from lung cancer screening in high-risk patients.

Monitoring Cumulative Dose from Multiple CT Scans

new study presented at the American Roentgen Ray Society (AARS) meeting brought attention to another key point in radiation dose reduction. Currently, a majority of the focus on cutting CT scan radiation is centered on dosage levels, but it is also important to monitor cumulative dosage in patients receiving multiple scans. While government and industry are increasingly focused on single CT scan dosage reduction (which is great news!), there is a lesser concern for decreasing the overall number of CT scans for patients.

The research tracked the amount of repeated CT exams performed on patients in order to calculate cumulative radiation dosage. Some of the results are shocking. The study identified a group of patients from the test population undergoing more than 20 medical imaging exams in one year, and as a result, being exposed to high cumulative dosage—more than 300 mSv per annum!  In fact, one patient received 70 different scans in one year!

This is, of course, something we are working to mitigate continuously. Europe (EEU) has been tracking the cumulative dose of its citizens for about 10 years—by law! This is certainly a good thing for patients and in the U.S, we are beginning efforts towards this direction. Several products are now available that serve as a repository for dose from devises and particular protocols, to keep track for individual patients (including cumulative).

We recently purchased such a product (DoseWatchGE Healthcare) which will be integrated with our RIS and connected to every radiation emitting device in our medical center. This product will pick up cases of unusually high cumulative dose in patients, but also identify protocols which have high dose or devices which are emitting high dose. We are looking forward to implementing DoseWatch a few months from now.

Be sure to check back regularly as we document our experience with the product.