The Value of Oral Contrast from the patient’s point of view

Oral Contrast

The authors raise this question from a patient-centered approach: “What would patients choose if given the option to drink or not drink oral contrast material, and why? Some patients might prefer a risk-averse approach and prioritize diagnostic accuracy, whereas other patients might prefer a comfort-based approach and prioritize examination comfort. Asking patients how they value these trade-offs can inform an optimal imaging strategy.”

Modern oral contrast (diluted Omnipaque) is tasteless and odorless. Most patients think they are drinking water. But, it significantly increases diagnostic accuracy, particularly in cases involving GI questions.

These authors concluded, “If oral contrast material has any diagnostic benefit, most outpatients (89%) would rather drink it than accept any risk for missing an important finding.”

Patients’ awareness of radiation dose and risks associated with medical imaging

In this article, the authors discuss how awareness of dose and risks of medical imaging by patients can facilitate shared decision making and reduce unnecessary radiation exposure.

Revolution CT Scanner at UW Medical Center Department of Radiology


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.

Ureteral Stones: Reduced-Dose CT Protocol in the Emergency Department

This recent article from Radiology reports the use of an 80% reduced dose CT protocol for assessing moderate to high risk patients for ureteral stones in an ED environment.

Reduced dose CT was correct for stone versus no stone in 100% of 108 patients. Dose reduction was achieved by lowering both the mAs and the kVp and adding iterative reconstruction.

Reducing dose via iterative reconstruction technology

As this article demonstrates, iterative reconstruction is a very powerful way to reduce dose without impacting diagnostic ability. Key points of the authors include, “To reduce patient and operator radiation dose involves optimization of medical imaging equipment and best control of the equipment by the operator. … The results of our study confirm in a large patient number reflecting the routine clinical setting that the image noise reduction technology allows a significant reduction in radiation dose.  … The substantially lower radiation dosage achieved in a routine clinical setting with the image noise reduction technique, provide further evidence of the substantial impact of the new technology. They indicate potential reduction in radiation dosage in invasive and interventional cardiology with more diffusion of newer radiation technology in clinical practice.”

The effect of trauma backboards on CT radiation dose

This article provides another neat bit of knowledge to consider when looking for lowest dose – though this is multi-factorial.

[Excerpt below]Backboard use in ED Figure 6

“Rate of backboard use during CT examinations of the chest–abdomen–pelvis performed in the ED from 1 January 2010 to 31 December 2012 (n=1532). Note the dramatic drop in backboard use in 2011 after multidisciplinary implementation of a policy for prompt removal of patients from backboards using primary clinical survey rather than waiting for a CT examination.”

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

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.

The importance of dose alerts

At UW Medicine, we use a dose alert system built into DoseWatch (GE Healthcare) as well as in the individual CT scanners. While this is a good safety mechanism to prevent accidents and notice high dose exams, it’s not the whole answer. As this article points out, “… in practice, CT technique and therefore patient dose depends very much on patient size.”

Size specific dose exposure (SSDE) is a better measure which we will be hearing more about in the near future.


CT Colonography: Reducing the Radiation Dose

This interesting paper talks about the use of iterative reconstruction to help lower the radiation dose of screening CT colonography.

Of course, as with all screening exams, the first order of priorities is to do no harm – hence the motivation to keep the radiation dose especially low.

The challenge is to lower dose without compromising diagnostic power.

For about the past two years, here at UW Medicine (Seattle) we have been using Model Based Iterative Reconstruction (VEO, GE Healthcare) for all our CT colonography exams. As recommended in this article, we also keep the kVp low – 80 or 100, which also helps to reduce the dose.

The result is a very low dose exam, but with excellent image quality and low image noise. This helps to make great coronal/sagittal reconstructions plus very nice 3D fly-through on the post-processing workstation.

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.

Radiation protection shielding

This article outlines the substantial reduction in radiation exposure to body parts which are shielded during a CT scan but not included in the field of imaging.

That is a very good practice.

More controversial is another practice: shielding sensitive body parts which ARE included in the field of imaging, specifically breasts, thyroid and gonads.

For some types of scanners this works well, while for other types less well.

With our scanners (GE) IF shielding to the sensitive body part is applied after the scout views are obtained, and IF the shield is separated from the body by placing towels or a blanket to elevate the shield off the body by 2-3 cm – then this works well. Any artifacts or other issues with image quality are minimal or out of the area of interest and the dose to the shielded body part does drop measurably.

Further, such shielding sends a strong message to patients and to our own staff about our concern for their safety.

Lowering radiation dose without affecting diagnostic confidence

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

How low can we go in radiation dose without affecting diagnostic confidence for detection of low-contrast liver lesions?

In a recent article we published, we studied the impact of incremental increases in CT image noise on detection of low-contrast hypodense liver lesions. Clinical CT liver exams were obtained on a 64-slice CT scanner using automatic tube current modulation at a routine clinical noise index 15.   An artificial image noise addition tool was used to increase the noise level in clinical liver CT images to simulate 75% (NI 17.4), 50% (NI 21.2), and 25% patient radiation dose (NI 29.7) scanning relative to the original images (NI 15.0; 100% dose).  The images were reviewed by radiologists of varying experience who subjectively scored lesion detectability on all the images, original and simulated.

We concluded that there is little loss of detection sensitivity for low-contrast liver lesion detectability of CT exams scanned with a NI at least up to 21.2 compared to a NI of 15, a patient radiation dose reduction of 50%. No significant degradation was observed when reader performance was evaluated as a function of lesion size (>10 mm) and contrast (>60 HU) at 90% sensitivity.  When lesion size dropped to <10 mm or contrast was <60 HU, sensitivity did drop to 85%.

This study had some limitations, the most important of which was that this study was a simulation and not a true study of CT scanning at lower radiation dose compared to high dose scanning which would have involved scanning patients multiple times. Nevertheless, this study was important as it demonstrated that dose could be reduced by 50% without affecting diagnostic confidence for detecting low-contrast liver lesions.

Achieving appropriate radiation dose for coronary CT angiography

This is an interesting addition to the sophistication of systematic lowering of kVp during CT coronary angiography. Of course, such sophistication strongly supports 30% dose reduction without compromising diagnostic power.

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.

A thoughtwise approach to CT iterative reconstruction

This very wise philosophy for implementing iterative dose reduction in any CT program was well presented at the recent MDCT meeting of the ISCT in San Francisco in June. A key component is to have regular and measurable ways for radiologists to regularly grade or score image quality as dose is ramped down slowly with increasing amounts of iterative reconstruction. With Model Based Iterative Reconstruction (MBIR), it may be possible to drop dose up to 60% compared to otherwise low dose adaptive statistical iterative reconstruction methods (ASIR) – but not in one jump. It takes time to get accustomed to the slightly different look of images with iterative reconstruction.

At least a month’s worth of experience should accrue before passing judgment on image quality. It is also important to guard against anecdotal cases used to render judgments, so experience over time is important. But with a methodical approach, a lot of progress can be achieved in overall dose reduction.

Lowering medical radiation dose with CT and other modalities in cancer patients

It is often said that radiation from diagnostic imaging is not an important issue in cancer patients.

But this report suggests otherwise – as expressed by oncologists.

Many patients with cancer are young and/or are being treated for cure. Many have long life expectancies despite having cancer.

And the basic principal of “Do no harm” plus that of ALARA still apply – as much to cancer patients as to any other patient with a serious disease.

So we should be striving for maximal diagnostic information from minimal radiation dose with CT and other modalities in cancer patients, too.

A Radiologist Replies to ‘Medical Radiation Soars, With Risks Often Overlooked’

A few weeks ago, the New York Times featured an article, “Medical Radiation Soars, With Risks Often Overlooked.” The article brought up some valid points about radiation, but also requires readers to take a step back when processing some of the information given.

Yes, as the article ascertains, radiation has its indisputable medical advantages, in addition to its potential medical downsides. The amount of medical imaging, including CT scans, has significantly increased over the last few decades, as more life-saving procedures are discovered and as technology develops. As a result, some patients are subjected to higher levels of radiation, which, according to this article, is “believed to account or 1.5 percent of cancers” in the United States.

The piece goes on to say that “the cancer-causing effects of radiation are cumulative” and that doctors and hospitals fail to track the amount of radiation patients have already been exposed to when ordering a new exam. While it is critical to practice “As Low As Reasonably Achievable” (ALARA) for every protocol and to closely scrutinize every exam request for appropriateness, there is absolutely no evidence that risk from well spaced CT exams is cumulative. Therefore, canceling an otherwise appropriate exam because of cumulative dose may not be in the patient’s best interests. For all CT exams a risk/benefit evaluation should be made by a well informed radiologist. For the existence of multiple prior exams alone to change the risk/ benefit ratio would be extremely rare.

Additionally, the claim that “no one” keeps track of how much radiation patients have been exposed to is inaccurate. A number of institutions, including UW, are a part of the American College of Radiology’s Dose Index Registry, a program striving to accurately track CT radiation dose in order to establish benchmarks, monitor patient radiation dose exposure, and compare patterns. More recently, a pediatric dose registry was introduced to perform similar functions, but for a younger demographic.

Both doctors and patients should be as informed as possible when it comes to radiation. Understanding the risk/ benefit ratio is an important part of this—and no appropriate medical imaging exam should be cancelled if it will benefit the patient, especially if its radiation level is ALARA.

Low-dose Lung Cancer Screening Too Costly? No…

I recently came across a study that questioned the cost- effectiveness of low-dose CT scans for lung cancer screening. As I’ve discussed before, there is sufficient and sound research validating that among high- risk individuals, low-dose lung cancer screening is a life saving process. However, this article claims that the medical imaging procedures may be too costly for the United States, “a nation struggling to control growing health care costs, even though some lives would be saved.”

This article clearly shows how charges relate to the execution of healthcare. At standard charges, screening CT of patient’s at high risk for lung cancer may not be cost effective. But, if these are regarded as add-on incremental cases and are priced at marginal cost (approximately $200), the screening equation may change and become financially viable from society’s prospective.

As with any screening program, the first caveat is to “do no harm” – hence an ultra-low dose CT technique would be advantageous. Similarly, figuring out how to keep the cost way down will be critical. I think we can….

AAPM Position Statement on Radiation Risks!

statement was recently released by the American Associating of Physicists in Medicine regarding how extremely low the risk of harm from radiation in diagnostic imaging studies is. Indeed, they state, it may be non-existent. I am absolutely delighted to finally see a statement like this in print, especially coming from the AAPM, a reputable and dignified organization.

In fact, this kind of statement has been needed for some time:

“Discussion of risks related to radiation dose from medical imaging procedures should be accompanied by acknowledgement of the benefits of the procedures.”

This sentence urges all providers, and even investigative news reporters, to do the responsible thing – discuss risks and benefits at the same time, in a balanced way, using language and concepts that patients can understand and grasp. Understanding extremely small risks (so small as to be potentially nonexistent) is very challenging for most of us – so it requires extra time and effort.

“Risks of medical imaging at patient doses below 50 mSv for single procedures or 100 mSv for multiple procedures over short time periods are too low to be detectable and may be nonexistent.”

Someone finally stood up and said it! The non-detectability of extremely low risk has stood the test of time. The non-existent risk possibility may be true and should be included in any discussion.

“Predictions of hypothetical cancer incidence and deaths in patient populations exposed to such low doses are highly speculative and should be discouraged. These predictions are harmful because they lead to sensationalistic articles.”

It is definitely possible that sensationalism may have resulted in patient harm – by inappropriately scaring some patients away from imaging. These medical imaging treatments might have helped them, whereas not getting the imaging might have harmed them by denying access to the diagnoses leading to correct and swift treatment.

In black and white: predicted cancer risk from these low doses is hypothetical and resultant deaths are only speculation.

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.

CT Scans and Patient Safety: The Debate for Solutions Rages On

A recent article addressing the ongoing debate over the safe use of medical imaging features the opinions of two industry experts on how we should be working to lower radiation doses from CT scans and other imaging exams.

On one side of the debate is Dr. Rebecca Smith-Bindman, who believes that it should be the job of the U.S. Food and Drug Administration to protect patients by regulating radiation from CT scanners. “Radiation doses are higher than they should be and they vary dramatically within and between facilities and that is not acceptable,” she said in the article.

Dr. Bruce Hillman, on the other hand, believes that the problem lies with doctors who order too many scans (which can lead to finding conditions that might have been better left untreated). And, according to the article, he thinks that “heaping more regulation on an industry that has already been squeezed by Medicare cuts may squelch the kind of innovation that produced CT scanners in the first place.”

In my opinion, there are three answers to this storm:

1.  We need to make greater efforts to strive for appropriate use of CT. For that we can turn to the best authority available: the American College of Radiology Appropriateness Guidelines. Computerized decision support programs in electronic medical records can help, too.

2.  We need to strive for much lower radiation dose per scan. We know that the dose per scan frequently can be reduced by up to 60 percent by the use of better CT techniques (selection of imaging parameters, shielding) and by modern CT technology. Here guidelines from organizations like the Society for Computed Body Tomography (SCBT/MR), an arm of the ACR, can be helpful and can drive education for all levels of healthcare providers.

3.  We need to ensure that financial incentives leading to conflict of interest are minimized, so that patients can be comfortable that any CT scans are done only for appropriate diagnostic investigation.

Finally, in all the storm about cost and radiation fear, we need to remember that CT is a very powerful diagnostic tool that provides definitive information which can be used to save lives and select the best therapy quickly. It does far more good than harm — in every institution, every day.

Low Dose CT Can Make Scanning Safer

Patient receiving a low dose CT scan which reduces radiation risk.It’s a fact of life that all CT scans involve radiation. And certain types of diagnoses and diseases are going to require regular repeated CT scans – resulting in a high cumulative CT radiation dose to the patient over time.  But as a recent news story profiled, there is a new technique and technology that can help reduce CT scan radiation exposure by up to 60%.

>watch the news story at

Researchers at the University of Washington have pushed the frontiers of CT technique by circumventing the noisiness and blurriness of images scanned at very low radiation dose. These noisy images are made sharp and clear by better software reconstruction technology. It’s a bit like what NASA does with high altitude satellite technology. This means that the same diagnostic power is achievable with much less radiation to the patient.

This new approach works for all types of CT scans, but can be especially important for  children and certain areas of the body – in particular, the female breast, the gonads and other tissues in the abdomen. These are particularly radiation sensitive, so we want CT scans to be as low in radiation dose as possible without compromising the diagnostic power of the CT scan. Low dose technique combined with low dose technology accomplishes this.

New innovations are continually being made in the field of medical imaging. If you need a CT scan, it’s always OK to ask your doctor if you can get one with a lower dose of radiation.

A Study in Cost Effective Care

Findings presented by researchers at the Radiological Society of North America’s RSNA 2009 event are shining new light on the importance of understanding cost effectiveness in CT scan use. In particular, I had the opportunity to design and perform a study that showed how the high negative predictive value of ECG-gated cardiac CT in low- to moderate-risk chest painpatients may allow an earlier yet safe discharge from an emergency department (ED) at a considerable cost savings.

For example, the standard of care for chest pain is an ECG, a blood test and a nuclear stress test – which keep a patient in the ED an estimated 30 hours and can cost as much as $8,000. A gated cardiac coronary CT angiogram (CCTA) done instead early during the ER visit could rule out coronary artery stenosis plus other causes of chest pain, resulting in the safe discharge of a patient in just five hours at a cost of about $4,000.

But it’s not just about finding ways to lower costs. By avoiding the nuclear test and doing a low dose CT, patients also reduce the total radiation dose – resulting in a safer overall procedure.

And this is just one example of the benefits that can be found in reexaminating some of the traditional approaches to diagnosis and medical imaging.