New National Dose Levels Established for Common CT Exams

Dr. Kanal’s Research Establishes New National Dose Levels for Common CT Exams

Kalpana M. Kanal, Ph.D., a medical physicist, professor and section chief in diagnostic physics in the Department of Radiology at the University of Washington School of Medicine, Seattle, and colleagues examined actual patient data from the American College of Radiology (ACR) CT Dose Index Registry to develop size-based DRLs that enable healthcare facilities to compare their patient doses with national benchmarks and more effectively optimize CT protocols for the wide range of patient sizes they examine.

The use of DRLs have shown to reduce overall dose and the range of doses observed in clinical practice.

Dr. Kanal’s research is published here in Radiology.

This landmark work is very helpful in benchmarking CT dose levels. It will be widely cited, I predict. Congratulations, Kalpana!

Kalpana M. Kanal, Ph.D.

Adopting Best Practices for CT Radiation Dose Monitoring

In this article, the research conducted by University of Washington Radiology Fellow Dr. Achille Mileto and colleagues highlight the importance of dose monitoring, but also the challenges: “Successful efforts to reduce overall radiation doses may actually direct attention away from other critical pieces of information that have so far been underappreciated, namely the widespread variability in global radiation dose values across clinical operation volumes.” … “These data may provide a foundation for the future development of best-practice guidelines for patient-specific radiation dose monitoring.”

Dr. Achille Mileto from the University of Washington

“We are kind of obsessed with radiation dose reduction, but I think we should keep in our minds the concept of radiation dose optimization, which means trying to adjust the dose to the specific clinical task,” Mileto said. “With technology we are reducing the dose, but we are increasing the room for variability. This is great if you are consistently reducing the dose, but we really want to understand what’s going on in terms of variability. So I think the main lesson is to try to develop best-practice guidelines for patient-specific radiation dose monitoring. I think basically the scenario in the near-term future will be to create some kind of shared library for radiation doses.”

CT technique and technology

This article highlights the wide variation in CT patient radiation dose between similar institutions for similar exams. Recent analysis of ACR dose registry data also suggests there is wide variation amongst different regions of the country.

Such variations suggest that attention to the details of CT technique and technology can produce CT exams at much lower dose – presumably without compromising diagnostic power.

Communicating with Patients

There is no question that a radiologist who consults directly adds substantial value for both referring physicians and patients. As we make exams more appropriate, we should probably plan on spending more time as consultants and meet the patients, as this article explains.

Jenny Favinger with patient at SKC Oct 2015

Radiologist at free clinic

Pictured above: UW Medicine Radiology Chief Resident Jennifer Favinger and Resident Derek Khorsand consulting with patients at the Seattle/King County Clinic

Images courtesy of UW GME

Gentle and wise use of CT radiation dose

This comprehensive article demonstrates the importance of CT dose monitoring and utilizing strategies to achieve ALARA (as low as reasonably achievable) doses while maintaining image quality for optimal clinical diagnosis. The authors also describe how the use of technology can improve the radiation dose efficiency of CT scanners.

Radiation Dose Management in CT: Is it easy to accomplish?

Guest blog by Kalpana M. Kanal, PhD, Direc­tor of Diag­nos­tic Physics Sec­tion and Asso­ciate Pro­fes­sor in the Depart­ment of Radi­ol­ogy at Uni­ver­sity of Washington

At the AHRA conference in Las Vegas recently, Dr. Pizzutiello, a medical physicist, discussed the complexity of CT radiation management and monitoring in diagnostic imaging. With the growing use of CT exams being performed and radiation dose in CT being a hot topic in the radiology community, it is imperative to monitor radiation dose from the CT exams as well as observe trends over time. Regulations now require that CT dose has to be documented and available on demand, CT protocols be revisited on an annual basis and incidents with high dose CT exams be reviewed. Several states around the US have CT regulations or are in the process of regulation implementation. It is a monumental task to monitor and manage dose, especially for large hospitals.

There are several dose management software products available that can help in managing the dose. Dose management is, however, a team effort and it is not possible to do this effectively without a team of radiologists, technologists, and medical physicists participating in this important task.

At our institution, we have been managing dose using a commercial product, Dose Watch (General Electric Healthcare) and also have a radiation safety committee within the department to review dose trends and make intelligent decisions based on our dose data. We have also been participating in the ACR CT Dose Index Registry since its inception and review our trends and benchmark values to our peer institutions. This is definitely a good idea if one is unaware of dose trends at their institution and how it compares to others around the nation.

Dose monitoring is complex but a necessary patient safety tool and, if well planned, can be accomplished and maintained with the help of dedicated professionals who understand the importance of the task.

Low dose techniques for urinary stone detection

This article highlights that it is possible to achieve much lower radiation dose CT scans for commonly employed types of CT studies – the CT for urinary tract stones is one of the most common.

While not done everywhere, attention to detail can produce remarkable reductions in patient radiation without compromising diagnostic power.

Use of a lower kVp will actually make stones a bit brighter.

Careful attention to patient centering in the gantry can make a difference of up to 40% in dose.

And the use of iterative reconstruction techniques is now widely accepted to not compromise detection, yet with marked dose reduction – whether it be statistical iterative reconstruction, model based iterative reconstruction, or some blend of the two.

Radiologists and technologists both need to understand the importance of these tricks and the physics behind each.

Optimizing Radiation Dose

Standardizing dose description parameters and metrics is an ongoing and very active area in ACR and nationwide. This will be a big help to comparing metrics between institutions and over time. The SSDE (Size Specific Dose Estimate) is a good step in that direction.

But this article also points out the large impact of exam appropriateness on dose. It is an impressive fact that a profound way to lower population dose is to avoid doing inappropriate exams. Tools such as the ACR Appropriateness Criteria or Computerized Decision Support at the point of order entry can empower appropriateness review. And every radiologist needs to increase their awareness of exam appropriateness in daily work.

Applying Appropriate Use Criteria to Medical Imaging Decisions

It is still true that the best way to maximize value and impact on disease while minimizing cost and radiation dose is to do only appropriate exams and not do inappropriate exams. But how to decide what is appropriate? Many of the standard criteria – such as those published by the ACR – are as evidence based as the current peer-reviewed literature evidence will support. But sometimes there may not be scientific evidence available for a hard clinical question – particularly if a randomized trial might be very expensive and take a long time. Under those circumstances, expert opinion is often a pretty good alternative.

Expert opinion can be incorporated into computerized decision support programs but also into daily practice. Indeed, every radiologist is on their own an expert in imaging and its appropriate use – which is valuable if they use this local expertise to guide choice of exams through being a consultant.

Your practice should make radiologist consultation easy to access … and widely known as a valuable service.

See this article.

Striving towards ALARA

This direction of combining a higher noise index (NI) to get lower dose images and then correcting for the resultant noise by using an increased percent of iterative reconstruction (ASIR) is exactly the way to go when striving towards “as low as reasonably achievable” (ALARA) – in my opinion.

At UWMC, we have for a couple of years now gone even further – we use NI in the 30-36 range and routine 70 percent ASIR as a standard for all our CT imaging except high resolution lung (which is NI 25 and ASIR 30%). According to the ACR CT Dose Registry, we are in the bottom 10% of their data base for CT dose….. but the images are very good.

Check out this article to learn more.

Despite Initial Challenges, ACR Dose Index Registry is a Success!

The American College of Radiology’s (ACR) CT Dose Index Registry (DIR) program was introduced in May 2011. The DIR is a data registry that allows institutions across the United States to send their anonymized CT exam dose information to the ACR to be saved in a database at ACR. Institutions are then provided with semi-annual feedback reports comparing their results by body part and exam type to aggregate results for adult and pediatric exams. Facilities can then compare their CT dose indices to regional and national values.

At UW, we enrolled in the DIR in May 2011 and since then have been sending encrypted DICOM structured dose report files from all of our CT scanners to ACR. Doing so required collaboration between ACR, IT, PACS personnel and the on-site physicist. Implementation involved several challenges, including software installation and data transmission consistency problems. Since numerous institutions are involved, the ACR required an exam mapping process via the Radlex Playbook to unify the protocol classification. This mapping process has been the most challenging factor in the implementation process. These challenges have been overcome and data is being successfully transmitted to and analyzed by the ACR.

The first report comparing adult patient dose data (CTDI and DLP by medical examination and by scan) between our site and others around the region and country was made available in January 2012 and the second one in September 2012.  For each exam, the report includes box-plots and histogram data for a variety of standard protocols.  The second report estimated the size specific dose estimate from the scout for each patient exam.

The ACR CT Dose Index Registry program has been very successful and is a useful tool for dose data mining and will eventually establish national benchmarks for CT dose indices.

For more information on the Registry, please see this article here!

Choosing Wisely Campaign: ACR’s Recommendations Accurate!

The Choosing Wisely Campaign is a recent initiative of the ABIM Foundation to encourage physicians and patients to take a second look at tests and procedures that may be unnecessary… and potentially, harmful. The American College of Radiology was one of nine US specialty societies that developed lists of the Five Things Physicians and Patients Should Question.

See the ACR’s outlined recommendations of the procedures that should be utilized less in radiology practices:

• Imaging for uncomplicated headache, absent specific risk factors for structural disease or injury.
• Imaging for suspected pulmonary embolism (PE) without moderate or high pretest probability of PE.
• Preoperative chest x-rays without specific reasons due to patient history or physical exam.
• CT to evaluate suspected appendicitis in children until ultrasound is considered an option.
• Follow-up imaging for adnexal (reproductive tract) cysts 5 cm or less in diameter in reproductive-age women.

All five of these recommendations are ones that I would certainly agree with. In fact, I wouldstrongly emphasize that CT for possible pulmonary embolism in young women be avoided unless there are clinical criteria which raise suspicion to at least moderate level. Additionally, ultrasound is a great modality to check for appendicitis in children, especially those that are young and/ or thin.

For the full recommendations by the ACR, please see here. Remember, informed patients are an integral part of the Choosing Wisely campaign.

ACR Releases Radiation Safety and Medical Imaging PSAs

The American College of Radiology, in an effort to address questions and concerns about radiation risk, has created several public service announcements that inform viewers where they can obtain more information regarding radiation in medical imaging. These PSAs have been released for nationwide broadcast.

The adult-focused version of the announcement directs viewers to the Image Wisely site, while the pediatric version directs viewers to the Image Gently site. Each site individually serves as the primary resource for additional information on imaging and radiation safety.

The PSAs can be found here.