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.”

 

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.”

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.

CT colonography

Using model-based iterative reconstruction, CT colonography can be a very low radiation dose method of screening. This article applauds the United States Preventive Services Task Force (USPSTF) approval, cited as a “big win for patients.”

CT dose reduction in assessment of active Crohn’s disease

This article illustrates how iterative reconstruction can be used to markedly lower CT radiation dose without significant impact on diagnostic content in CT exams.

For patients with Crohn’s disease who likely will have multiple CT exams over time, lowering dose is especially important.

Decreasing radiation dose in CT for COPD patients

Study concludes that ultralow-dose CT may substitute for standard-dose CT in some COPD patients

There are at least three different generations of iterative reconstruction, all of which enable substantial CT dose reductions without compromise of diagnostic power. While earlier versions of IR yielded 30% dose reductions, those with model-based IR or some blend thereof can result in 50-80% patient radiation dose reductions – with even better spatial and low contrast resolution. Access the full article on this study.

Novel iterative reconstruction method for reducing CT dose

All iterative reconstruction techniques powerfully reduce CT radiation dose in the 40-80% range – without compromising diagnostic power. And they all continue to be refined and to evolve, as this article illustrates. While the “look” of CT images may change from the noise removal, the diagnostic power is not compromised despite the substantial dose reduction. As radiologists, working with change is our future. The old days of nothing but filtered back projection are in our history but not in our future.

Low-dose Radiation

Low-dose Radiation Not Harmful

To quote the American Association of Physicists in Medicine:

  • The risk from medical diagnostic radiation in doses below 50 mSv as a single dose or 100 mSv as a cumulative dose is too small to be measured and may be non-existent.
UW Medicine Physicists

UW Medicine Physicists

Detection of pulmonary nodules with low-dose CT and iterative reconstruction

This article illustrates how much good diagnostic information can be obtained using very low CT radiation doses when screening for lung nodules.

In the screening environment, doing no harm is especially important since so many patients are screened. But detection rates cannot suffer.

Here is encouragement that we can meet both goals with very low dose CT combined with iterative reconstruction.

Low-dose CT enterography

This article pretty well confirms what many have felt: model-based iterative reconstruction (MBIR) lowers radiation dose by 70-80% compared to adaptive statistical iterative reconstruction (ASIR), without loss of diagnostic power/information. While the images do indeed look different because there is much less noise and because of a slightly different pattern in the remaining noise, all the findings are there. Further, the anatomy and the findings are displayed as well or better.

So, in a young patient (under age 45) – especially if they are likely to be getting multiple exams – use of model-based iterative reconstruction is well worth the longer reconstruction time.

(To read more about CT enterography, Radiologyinfo.org is a great resource for patients.)

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.

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.

 

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.

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.

Annual screening for lung cancer low-dose CT

This is a major advance as American healthcare evolves from reactive to preventive.

But a key to success in this lung cancer screening program is keeping the radiation dose of each exam as low as possible – certainly well below one mSv. Ideally, a low dose approach would involve model based or some other form of iterative reconstruction. All the other techniques to minimize dose should be employed together. Fortunately, this is an application where very low kVp will work well (70-100).

Next – and possibly even more impactful: coverage for screening CT colonography.

Reducing radiation dose for CT enterography

Since many patients who get CT enterography have repeated exams (inflammatory bowel disease, etc.), Model Based Iterative Reconstrucion has primarily been used to markedly reduce radiation dose while maintaining acceptable image quality.

However, this might be another application – especially if the patient will have only one such exam.

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.

Low-dose CT technique in diagnosing Crohn’s disease

Patients with Crohn’s disease often are young and often have their disease activity assessed repeatedly with CT – though MR is used more frequently now as well.

So – they are good candidates for reducing radiation dose by means of iterative reconstruction.

This paper demonstrates that considerable reduction of dose can be achieved without damaging image quality.

CT radiation dose reduction by iterative reconstruction in lymphoma staging

There are some who say that iterative reconstruction should be reserved only for younger patients and not used on older cancer patients who already have serious disease.

But many patients with malignancies are younger or are being treated for cure.

This article suggests that an iterative reconstruction technique (such as model-based iterative reconstruction, MBIR) which can reduce patient radiation dose by 50% may have salubrious utility in patients with lymphomas – who often are younger, who get multiple CT scans, and who are being treated for cure.  

This may apply to other malignancies as well.

Educating patients about radiation dose

The ultimate goal is to have a fully informed and well educated patient – this will result in best personalized healthcare and outcomes.

So as far as radiation dose from individual CT exams is concerned, it is good for patients to know what they received – but it is not enough. Patients also need to be educated about the meaning and risk of their radiation dose.

Educating patients about extremely low risk is difficult – as would be true about any very low risk. But, it should be coupled with educating patients about the potential health and healthcare benefits from their CT exam.

This is because what they really need to know is their risk/benefit ratio – from each CT exam. An educated patient who understands their risk/benefit ratio from CT will be a truly informed healthcare consumer.

Who should educate patients about risk and benefit? All of us – all providers. The primary care physician, the subspecialist, the radiologist, the CT technologist, the radiology nurse, PA’s and LPN’s – everyone who contacts the patient can help advance this education and this understanding.

MDCT 2014 speakers weighed in on this subject at the ISCT Symposium in early June.

Significant radiation dose reduction without sacrificing image quality

At the 2014 ISCT-sponsored MDCT meeting in San Francisco – dose reduction was a key theme during all four days.

Iterative reconstruction was a common theme of an overall dose reduction program. While adaptive statistical iterative reconstruction (ASIR) now has been well-shown to reduce average doses by up to 40% without impact on image quality, the hot topic was model-based iterative reconstruction (MBIR) in its various forms.

Consensus is now developing around MBIR being capable of 50-70% dose reductions incremental to adaptive statistical iterations. While image appearance may be somewhat different from that of filtered back projection, it is now pretty clear that such different appearance does not compromise diagnostic power. Indeed, with experience, some radiologists have developed a preference for the image appearance of MBIR.

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.

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.

Get Started! Steps for Implementing Dose Reduction Programs.

At a recent Society for Pediatric Radiology (SPR) meeting in San Francisco, one presentation addressed low-dose CT’s “bright future, but troubled present.” Texas Children’s Hospital’s Dr. R. Paul Guillerman touched on the many uncertainties and challenges involved in low-dose radiation optimization, citing that these goals are so complex that they may nearly be impossible.

But, let’s take another look at this. Yes—dose reduction is complex and full of potential traps leading to poor technique or image quality. However, that is not a reason to avoid implementing a dose reduction (technique optimization) program at your institution!

So, how do you lead your institution down a road towards dose reduction? First, start with Google. Read what you can find on the topic. Then, go to meetings, talks, and presentations given by experts with considerable experience in the endeavor. Finally, start at your own institution.

I would suggest trying one variable at a time. Implement a weight based (or cross-sectional area based) kVp selection program. Then, embark on understanding how to use weight (or BMI) based selection of Noise Index for automated tube current modulation. Don’t forget to check out the easy stuff – like patient centering, use of bismuth shields, and limiting Z axis. Realize that even your contrast injection protocols – volume, rate, blending – might benefit from a weight based approach. Decide how to implement iterative reconstruction, varied by body region.

With these steps you are set to embark on a continual journey. Get started… today!

Further Validation: American Lung Association Supports CT Screening!

Another major organization has joined the U.S. National Cancer Institute to support CT lung cancer screening as a life saving procedure! Recently, the American Lung Association updated its recommendations to support low-dose CT lung screening for smokers and former smokers.

Lung cancer continues to be the leading cause of death in the U.S., with more than 150,000 deaths annually and a five year survival rate as low as 15 percent. However, research from the US National Cancer Institute’s Lung Cancer Screening Trial gives promising hope. The study found that low-dose CT can reduce mortality rates by at least 20 percent among smokers and former smokers. Other published reports have estimated even higher rates of mortality gains! According to the LCST, individuals between the ages of 55 and 74 years who are current or former smokers of at least 30 pack-years and have no history of lung cancer are ideal candidates for lung cancer screening with CT.

Currently, besides never smoking, low-dose CT screening is the only viable option for significantly reducing the risk of lung cancer. The ALA’s recommendation of this medical imaging exam is an important step toward the development of widespread population-based CT screening program through the U.S.

The ALA joins the National Comprehensive Cancer Network, the first major professional organization to recommend low-dose lung cancer screening last fall.

For more information on factors that may effect the widespread implementation of lung cancer screening, see this post on low-cost screening.

Is Low-cost a Benefit for Lung Cancer Screening?

Is low-cost an added benefit to widespread lung cancer screening? According to this article, from April’s Health Affairs—yes!  The study on this much debated about topic asserts that routine CT lung cancer screening of high-risk individuals would save thousands of lives annually for less than one dollar a month per patient, if implemented throughout the US. According to these figures, the cost of low-dose lung cancer screening could be less than that for both breast cancer screening and colorectal cancer screening.

As we’ve pointed out, lung cancer screening is effective and life saving.  For high- risk patients, those who are multiple pack year smokers for 25 years or more, screening provides significant benefits. For these individuals, low-dose CT screening reduces the number of lung cancer deaths by 20 percent!

Despite this, widespread lung cancer screening has yet to be implemented nationwide, largely due to cost. This study reports interesting and encouraging data about widespread implementation of the procedure, though. However, we must remember that there are also reputable articles which report much higher cost numbers when adjusted for quality-life-years saved. It is necessary to take these studies into account, too.

Looks like the jury may still be out on this one!

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….

The Truth about CT Exposure: 1980 to 2012

recent article published in CA: A Cancer Journal for Clinicians states that education of referring physicians, more assertive radiologists, and an increased use of healthcare IT are the keys to reducing patient exposure to radiation.

While these assertions may be true, the article also touched on rising radiation exposure due, primarily, to CT scans. Since the early 1980s, the estimated per capita dose from medical radiation in the US has increased significantly. But this isn’t the whole story…

While it is true that medical radiation from CT has increased markedly since 1980, so has the benefit to health from CT. We no longer do “exploratory surgery” for example, in order to sort out complex diagnostic imaging challenges. The false negative rate from Appendix surgery has plummeted. And cancer diagnosis rates overall are declining while cancer cure rates have gone up substantially, particularly in the last 5 years.

Meanwhile, the radiation dose per CT scan has gone down dramatically as the principles of low-dose CT continue to be better understood and implemented. Scans that used to require 25 mSv of radiation are now being done for 20% of that amount. While negative effects from low dose radiation have never bee proven (below 50 mSv), we still strive to keep our doses as low as possible.

So the issue is not radiation cost, but cost/benefit ratio. Driving a car is dangerous too, but we accept the cost/benefit ration. For CT that ratio is much better!

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.

NCCN Confirms Importance of Lung Cancer Screening

Recently, the National Comprehensive Cancer Network has come forward in favor of lung cancer screening with low-dose CT. The NCCN is the first professional organization to perform the comprehensive review and update their recommendations to promote lung cancer screening.

This update further validates the key concept that high risk patients benefit from screening. High risk patients for lung cancer diagnoses are those who are multiple pack year smokers for 25 of more years. For these individuals, low- dose CT screening reduces the number of lung cancer deaths by 20 percent.

While we don’t really know the full cost of a screening program – such as the costs of working up false positive CT findings,  the benefit in lives saved seems to justify considering screening now.

Fortunately, the CT technique for screening is low dose and involves low radiation dosage.

Dual- Energy CT: Less Radiation, Higher Image Quality

recent presentation at the 2011 International Society for Computer Topography (ISCT) meeting in San Francisco highlighted the effectiveness of using dual- energy CT for abdominal imaging. This CT- technique has become more promising for uncovering certain pathology that has otherwise been hidden by traditional diagnostic imaging procedures.

Dual- energy CT- by whatever technology – can be configured to employ less radiation than single energy CT. But for some specific applications, it produces more diagnostic and specific information. Dual- energy CT currently may be the best radiology technique for characterizing urinary tract stones to their chemical composition (which determines whether medical, shockwave, or laser therapy will be required), characterizing small renal masses, and characterizing liver masses into cyst versus tumor.

Additionally, dual- energy CT may apply to better detecting minimal liver tumors, lowering the amount of iodine needed for CT angiograms, and creating virtual non- contrast scans. The latter may reduce the overall CT radiation dose of a multi- phase study by 20 to 50 percent!

While dual- energy is still relatively new to the field, it is clear that it is a promising technique for CT dose reduction, while maintaining imaging quality. Further research and testing will be conclusive of the absolute benefits of dual- energy CT.

Abdominal CT Scans: How Low a Dose is Low Enough?

I was recently asked the question: “How low is low enough for CT?” With the risks of CT scans, the answer is: as low as you can go without significantly compromising diagnostic power.

Sometimes we do very noisy CT exams at extremely low doses, knowing that we may miss a 1 mm ureteral stone. However, we accept that possibility since such a small stone may not be clinically relevant.

Our routine abdominal/ pelvic exam is noisier than most of the CT exams we see referred in – but we deliberately chose to become accustomed to the higher noise levels (even when using  iterative reconstruction) in order to minimize CT radiation dose. Thus, our doses are 40 percent lower than those on some of the CT scans we see being administered at many other places. There is no evidence we have compromised diagnostic power with our reduced dosage CT scans.

In today’s world, the 1-3 mSv cardiac CT is commonplace. In the near future, a CT of the abdomen and pelvis (40 cm of Z axis) using 0.6 mSv will soon be commonplace with the arrival of model based iterative reconstruction. With MBIR recently becoming available in the United States we will soon see dose reductions of up to 80 percent!

Professional Recommendations for Low Dose Optimization

I came across an article from the Journal of the American College of Radiology on a number of recommendations for optimizing patient dose level in chest CT scans, the third most commonly performed CT exam in the country.

As the article points out, the lungs are an ideal organ for low dose radiation CT scans. Some of the recommendations offered include:

  • Doctors should ensure that patients understand all instructions fully, including when to hold their breath and how much movement is permitted.
  • Automated exposure control (AEC) techniques should be used as often as possible to assist with breathing in children and adults.
  • Iterative reconstruction techniques reduce radiation dose exposure substantially and should be performed as often as possible.
  • Centering patients in the gantry isocenter avoids excessive scan length dose. Additionally, CT scans should only be performed on the area of indication.
  • Reading thicker sections ensures CT scan radiation risk reduction, while allowing fine details to be examined in nosier, thicker sections. This procedure should be utilized by imaging professionals.
  • All CT scans should be done for a clinical and justifiable reason.

The tips and pointers in this article are all good tools for lowering patient radiation dose in chest CT. We have found that the use of iterative reconstruction is a big help – lowering dose by as much as 40%. Now that model based iterative reconstruction has recently become available in the USA (GE’s version is called VEO), we can look for dose reductions of more like 80%!

Radical Breakthrough in the Drive toward Lower Dose

GE recently announced the introduction of a breakthrough low- dose imaging reconstruction technology in Canada. This CT image reconstruction technology, called Veo, is the first Model- based Iterative Reconstruction (MBIR) technique.  The technology is a response to radiologists’ demand for a technique that maximizes CT image clarity and quality while optimizing the dosage level for patients’ safety.

MBIR is indeed a radical breakthrough in the drive toward lower dose CTs. While very computationally intensive, this technique allows marked reduction in patient dose from CT (by up to 80% or greater), yet also provides some improvement in spatial resolution without compromising contrast resolution. How could all that be possible – seemingly defying the laws of physics? The answer is in the much faster computational speeds of the modern computer chip.

The University of Washington will be part of the group assessing the degree to which MBIR, commercially known as Veo, outperforms more traditional CT reconstruction techniques.

New Data on Lung Cancer Screening Shows Low Dose CT Saves Lives

Earlier this year, I wrote a blog entry about the news surrounding an important study involving CT and lung cancer screening. Now, the same study is making big headlines again as stronger (final) findings have been released. According to CNN, the study found that “low-dose CT screening reduces the number of lung cancer deaths in high risk smokers by 20 percent.”

Here’s another interesting fact coming out of the latest data: In high-risk populations, lung cancer CT screening can save a life for every 300 people screened. That’s more potential lives saved than mammography, colonography and prostate cancer screening COMBINED!

The only hitch: lung cancer CT screening is not covered by most insurance. However, many hospitals and imaging centers are offering this service at attractive rates for those who are willing to pay themselves.

An Interview with Dr. Mitsumori on Weight-based Selection of CT Parameters

The following is an interview I conducted with Dr. Lee Mitsumori, Assistant Professor of Radiology at the University of Washington.

Dr. Shuman: Please give us a brief overview of your work involving weight-based selection of CT parameters.

Dr. Mitsumori: We have been investigating the use of body-size-dependent CT scan parameters to optimize the radiation dose of each scan. Several imaging parameters can be modified at the time of the CT that can alter the amount of radiation of the scan (tube current, tube potential, scan range, scan phases, image reconstruction techniques). The challenge is to adjust each so that the final set of patient images are of diagnostic image quality and were obtained with the lowest possible radiation dose. The risk is that incorrect settings or too aggressive dose reduction can create a scan that is of poor image quality that does not allow a correct interpretation. Current work at University of Washington Medical Center involves studies comparing different CT image reconstruction techniques (adaptive iterative reconstruction, model based iterative reconstruction) that can significantly reduce CT image noise and how these can be best implemented in patient CT exams.

Dr. Shuman: Why is weight an important concern regarding CT? How does weight affect CT?

Dr. Mitsumori: A patient’s body size, as reflected by weight, affects two important feature of a CT scan. The first is the amount of photons needed to generate an interpretable CT image. A CT is a projection technique, where an x-ray source emits photons that then pass through the subject before being recorded by a detector on the other side of the patient. Larger patients need more photons with higher energy than smaller patients to create images that can be correctly interpreted. If the CT parameters are not correctly set and only a small number of photons are recorded by the detector, the images created are noisy. If an image is too noisy, the interpreting physician may not be able to see if a problem or disease process is present. Unfortunately, the more photons used the higher the radiation exposure of the CT exam. While large patients are at risk for having noisy images, small patients can have scans done with parameters selected for an average sized patient, in which case too many photons are used than what would be needed to create diagnostic images. Thus, the importance of matching the radiation dose (number and energy of photons emitted) with the patient’s body size to prevent non-interpretable studies in larger patients, and avoid excessive radiation dose in the smaller patient.

The second feature of a CT scan where patient size is important is in the amount of iodinated contrast needed for the scan. Iodinated CT contrast is injected intravenously during the scan and improves the depiction of the different organs and vascular structures in the body. With CT imaging, the use of contrast greatly improves the radiologist’s ability to differentiate diseased (tumors, infection, inflammation) from normal tissues. Similar to radiation dose, the amount of contrast needed to enhance the organs is dependent upon patient body size. Small patients will have smaller organs, less blood volume, and be shorter than larger patients. Thus the amount of CT contrast needed may not be the same for every patient.

Dr. Shuman: What are the risks involved when a hospital or imaging center does NOT take a patient’s weight into account?

Dr. Mitsumori: The risks for scanning with fixed CT parameters are that when compared to an average sized patient, the large patient may have scans with noisy CT images that could lead to interpretation errors, or a non-diagnostic scan in which the scan may need to be repeated or an alternative imaging test performed. For the smaller patient, the risk would be that more radiation is used than what is needed to generate adequate, diagnostic images.

Similar risks occur with CT contrast administration. If a fixed amount of contrast is used for every scan that is based on an “average” patient size, then large patients may not receive enough contrast to adequately enhance the internal organs rendering the scan potentially non-diagnostic, and the small patients are given more than the amount of contrast needed to obtain an adequate scan.

Dr. Shuman: When discussing CT exams with their doctors, are there questions a patient should ask regarding their weight? In other words, what would make an “informed patient” as it relates to weight and CT?

Dr. Mitsumori: An informed patient would want to ask if their CT scans will be performed with “patient tailored” or “patient specific” protocols that use the amount of radiation and iodinated contrast that best match the patient’s body size.

Iterative Reconstruction at UW: an Overview

I am often asked what, exactly, iterative reconstruction is – and why it is so important. I thought it would be a good idea to discuss what I do and what my work means for the University of Washington Medical Center and our patients.

A brief overview of iterative reconstruction

Iterative reconstruction to us means potentially significant radiation dose reduction to our patients, but the look of the CT image itself needs some getting used to. When we first got the option on our scanners, we wanted to make sure that our radiologists would be comfortable with the images produced.

So, based on our protocols at the time, we reconstructed them with varying percentages of iterative reconstruction and noise indexes, and had our radiologists evaluate the images and decide what they found to be the most similar in noise and image quality to our standard at the time.

They used a double-blind method to evaluate the images, and based on what they decided, for noise index and iterative reconstruction percentage we were able to reduce radiation dose to our patients by 40-60 percent.

The evolution of iterative reconstruction at UW

We are constantly striving for improvement in image quality and dose reduction – both of which lead to better patient care. So we look again at our existing protocols and evaluate how we can combine certain series or opt for higher noise indexes in order to reduce dose. We also introduce different percentages of the iterative reconstruction and display these for our radiologists to further evaluate.

What UW is doing that others aren’t

Our radiologists are always willing to go out of their comfort zone in order to reduce dose. I say this again because of their willingness to take the time to look at images that traditionally would not be pleasing to their eyes, but may be more than adequate for answering the questions that the ordering physicians need.

And, again, a prime example of that is the different percentages of iterative reconstructions that they’ve seen and continue to look at, in order to properly evaluate the balance of dose vs. image quality – and always striving to improve both.

Why this work is important for patients

We always put patients first. To do this, we need to make sure that we give the right amount of radiation dose. With the modern machines we have, it is far too easy to give too much dose to produce the prettiest of images, but easy is not safe. To use these modern machines properly and responsibly takes a lot of extra work to accurately and safely fine tune each protocol for each patient’s needs. Our patients deserve all of that extra effort and more.

Adaptive Iterative Reconstruction Article Featured on Image Wisely

What does adaptive iterative reconstruction do? How is it used?

These are questions addressed in an article of mine featured on the Image Wisely website. As mentioned before on this blog, Image Wisely is an excellent and very useful resource – for both health care providers and patients – that provides information on low dose protocols, radiation risk, and safety in medical imaging.

To read the full article, click here.

Study by Dr. Kanal, UW Researchers Featured in JACR

Recent findings from blog contributor Dr. Kalpana Kanal and her team of University of Washington researchers have been published in the April issue of the Journal of the American College of Radiology!

The purpose of the study was to examine the variation in pediatric trauma head CT imaging protocols in Washington State – including the use (or not) of low radiation dose CT. Based on their findings, the team is now working on a campaign to adopt CT dose reduction protocols throughout the state. For more information on the study, click here.

Great work by Kalpana and her team!

CT Radiation Overexposure Still a Problem, Regulation Issues are Complex

Unfortunately, ct scan radiation overexposure continues to be a problem in hospitals and imaging facilities across the country. However, the question of regulation of dose from ct scanners is a complex issue. Many say that the best pathway to regulation is through the existing American College of Radiology mechanisms – such as certification of CT sites and subspecialty certification of both radiologists and CT technologists. This may expand to include requirements for regular monitoring of dose from typical exams and reporting the results of such monitoring to a central ACR registry.

Others advocate a role for the FDA, though that government agency may turn to a group of experts, such as the ACR or the Society of Computed Body Tomography. A national registry of individual patients which records dose from each CT exam for each patient, and cumulative dose for each patient, would also be a best practice – Europe does this now in the EU.

Finally, we need many and repeated courses, texts, electronic educational media, and monographs focused on the topic of how to consistently achieve CT scans at much lower dose than a few years ago. This education should be widely available and ongoing.

Our recent UW Symposium on Low Dose CT was a repeat from six months ago, and was equally well attended.

Second Low Dose CT Symposium Was a Great Success!

I am extremely pleased to report that our second, back-by-popular demand Low Dose CT Symposium went very well! It was attended by 140 healthcare providers, which was an impressive turnout. Talks were excellent and very engrossing. There was a great discussion panel for the final half-hour (it actually went on for another half-hour after the meeting since there was so much discussion coming out of the questions!). An audience survey score was 5.4 out of a possible 6 for quality and impact on practice.

Were you there? What did you think?

Ordering CT scans in the ER: Three Questions

One of the most common complaints of patients in the ER is abdominal pain, and as a recent article at TIME.com details, diagnosis is rarely straightforward. It is important to understand that the ER is different from other places where healthcare is provided. ER physicians see a broad spectrum of disease – from the insignificant to the life-threatening. There are great time constraints in the ER, as well, and follow-up care is hard to arrange (and may be unreliable) so there is pressure for a definitive diagnosis in a single encounter.

Physicians considering the CT scan to assist with diagnosis for abdominal pain or other illness and injuries should consider three questions:

1.  Is CT the right test to do for this patient?

Many ER physicians are good at a answering this question, but it is also helpful to remember that the best expert on appropriate use is one phone call away: the radiologist. Having the patient’s EMR handy is important, too, in reporting how many CT scans this patient may have had historically, since this is a data-point in choosing whether or not to do CT. A national registry of individual patient cumulative radiation dose is coming to the U.S., similar to the one that now exists in the EEU, but it is not here yet.

2.  If CT is the right test, what kind of CT?

With contrast or without? Oral contrast or not? Positive oral contrast or negative? One pass or three? Arterial or portal venous phase? Abdomen only or abdomen plus pelvis? Again, the radiologist is a valuable consultant for getting the most information about the patient’s condition at the least radiation cost.

3.  How can the CT scan be done with the lowest possible radiation dose?

Finally, once the kind of CT exam is decided, how can it be done with the lowest possible radiation dose without compromising the diagnostic value of the scan. A well-informed radiologist can reduce the radiation dose per scan by up to 60 percent. For example, CT of the urinary tract with contrast now can be achieved in a single pass. Careful attention to CT imaging parameters can radically lower dose (low kVp, modulated mA, etc.). Limiting the length of the scan on the patient and careful centering of the patient by the tech can greatly reduce dose. In addition, newer scanners combine better detectors with more complex reconstruction algorithms to substantially lower dose and CT scan radiation risks.

Upcoming Speaking Engagements

Just wanted to let you know about a couple of upcoming events…

First, I’ll be speaking at Overlake Hospital in Bellevue, WA, at the quarterly Meeting of the Association of Hospital Radiology Administrators on Low Dose CT. This is taking place on February 23, 2011, at 5:30 p.m.

Coming up in early March, I will be Visiting Professor at the University of California, San Diego. On Tuesday, March 1st, I’ll be attending Grand Rounds at 7:30 a.m., and speaking at the San Diego Radiology Society at 7:00 p.m.

Back By Popular Demand: Low Dose CT Symposium Set for March 12, 2011

The Low Dose CT Symposium is a repeat session of the October 10, 2010 symposium which drew close to 150 people and was greatly received! It will be an excellent opportunity to gain understanding of the current thinking about how to lower dose in CT scanning without compromising the diagnostic power of CT. Radiologists, physicists, and senior technologists are combining their knowledge and experience in multiple 20-minute talks about Low Dose CT technique, covering all aspects of protocols, technique, and ordering appropriateness for use of CT.

The half-day symposium is taking place March 12, 2011, in Seattle at the University of Washington Health Sciences’ Turner Auditorium, D-209.  The symposium is available for a maximum of 3.5 AMA PRA Category 1 Credits™. Registration is required to attend.

For more information on the event — and to register — please visit www.lowdosecteducation.com.

Here’s a guick look at the agenda:

8:00-8:30am Refreshments
8:30am Welcome William Shuman, MD, FACR
8:40am Why the Unexamined CT Can Be Very High Dose Kalpana Kanal, PhD
9:00am Low Dose CT Technique William Shuman, MD, FACR
9:20am Low Dose CT in the Abdomen: Practical Applications Carlos Cuevas, MD
9:40am Low Dose Techniques for Vascular CT Lee Mitusmori, MD
10:00am-10:20am Break
10:20am Low Dose CT: The Technologist’s Perspective Mario Ramos RT,CT
10:40am Low Dose Cardiac CT — Coronary Arteries, Whole Chest, and Beyond William Shuman, MD, FACR
11:00am Educating Patients about Radiation Janet Busey, MS
11:20am Low Dose CT in the Acute Care Setting Martin Gunn, MD
11:40am The Future of Low Dose CT Paul Kinahan, MD
12:00-12:30pm Questions and Panel Discussion
Adjourn

Hope to see you there!

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.

Important Studies on CT Scans and Lung Cancer Make Headlines, Generate Debate

In the last few months I’ve read several stories concerning research about CT screenings for lung cancer.

In mid-November, there was a story making the rounds among the major news outlets about a study that found that CT lung scans can reduce the risk of lung cancer death among former and current heavy smokers. During the excitement of this study, a New York Times piece was published that expressed concern that the study’s findings could easily be taken out of context – and perhaps incite unnecessary fear, as well as drive demand for unnecessary scans.

I’d like to point out the importance of this study: it showed a 20 percent reduction in mortality in patients at very high-risk who were screened with low dose CT compared to patients who were not. Several things to keep in mind about this study – first, it was a study of patients with 30 or more pack-years of smoking history. Second, the technique was a quick and a low dose CT. And third, the costs of false positive findings and their workup have not yet been analyzed.

Now, another study is gaining traction that provides even more support for the findings of the November study. While this data suggests that screening can lower lung cancer mortality substantially in high-risk individuals, what we don’t yet know is the cost of a QUALY – a quality adjusted life-year. Calculating that cost involves knowing how much society had to expend paying for CT exams and the costs of false-positive results in order to capture a saved life-year in an at-risk person. Generally, if you can save a QUALY for $50,000 or less, it’s worth doing. If more, it’s a debate.

Just some things I’ve been thinking about as more and more news agencies report on these findings. I’m interested in learning what you think – what’s your opinion on these studies? Was the New York Times piece correct in its cautionary tone? Or could these findings, in fact, be as revolutionary as some reporters (and researchers) want us to believe?

Year’s Biggest Advancement in CT Technology?

I recently came across this video from RSNA. About halfway in, they ask the question, “What is the biggest advancement in CT technology this year?”

I would agree with Dr. Siegel that iterative reconstruction has stimulated thinking and conversation among radiologists about how to substantially lower CT dose without compromising the benefits of CT. Based on our 18 months of experience, we know the reduction is at least 40 percent with the current version of iterative reconstruction. And we suspect much greater reductions are coming. Some of the issues centers around radiologists’ “preferences” for how a CT images looks. But preferences can change, even dramatically, when driven by the hope of much lower patient dose.

What do you think – what do you view as the biggest advancement in CT?

Obligation to Patients: Minimize Risk and Maximize Benefit

One of the most exciting – and talked about – sessions at RSNA was called “Radiation Dose: Can It Be Too Low?” The expert panel had a healthy debate on radiation dose and risk, and finally reached an agreement that CT scans should be limited to “justified and optimized studies.” (HealthImaging.com has a good recap of the panel’s discussion.)

The debate about risk can go on, but when practicing medicine (radiology) with real patients, the obligation is to both minimize risk AND maximize benefit.

So the challenge for radiologists is to lower dose as much as possible without compromising the amazing diagnostic power of CT. How to accomplish this is both science and art. But we have discovered at UW that with a combination of low dose technique and low dose CT technology, you can take out up to 40 percent of the radiation dose to the patient (compared to 3 years ago) without having any negative impact on diagnosis. So that number certainly is achievable at most sites.

Could we go even further in dose reduction?

Stay tuned…

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.

It’s National Radiologic Technology Week!

To recognize National Radiologic Technology Week, I asked respected CT technologist (and our CT supervisor) Mario Ramos to share his perspective on the benefits of low radiation dose CT. — Dr. Shuman

Proper dose reduction is not just about having the right equipment. It is essential that everyone is involved, and that they all work as a cohesive team in the name of patient safety.

Management supports us by making sure that the right machines, maintenance contracts and people are in place. Our radiologists ultimately determine the level of noise we allow in images, and that dictates the steps we take to reduce dose. As technologists, we have to have the right workflow in place to make sure that all those steps for dose reduction are done, such as adjusting kV, ma, noise index, and proper shielding. Our support staff assists with the busy work that can take away from the focus on the scan at hand, and the physics teams keep our QA/QC protocols in check. We are very fortunate here at the University of Washington to have all these things in place and know that as equipment and scanning techniques continue to evolve, we are able to ensure the highest level of image quality while maintaining proper dose reduction practices.

Low Dose CT Symposium Set for October 2

The Low Dose CT Symposium will be an excellent opportunity to gain understanding of the current thinking about how to lower dose in CT scanning without compromising the diagnostic power of CT. Radiologists, physicists, and senior technologists are combining their knowledge and experience in multiple 20-minute talks about Low Dose CT technique, covering all aspects of protocols, technique, and ordering appropriateness for use of CT.

The half-day symposium is taking place October 2, 2010, in Seattle at the University of Washington Health Sciences’ Turner Auditorium, D-209. Registration is required to attend. Attendance is free, but a $25/50 charge applies to those attendees requesting CME credit.

For more information on the event, please visit www.lowdosecteducation.com. Or to go directly to the registration page, please click here.

Note for attendees: We’ve already been approved for 3.5 AMA CME Category 1 credits for the activity; ASRT credits pending.

Here’s a guick look at the agenda:

8:00-8:30am Refreshments
8:30am Welcome William Shuman, MD, FACR
8:40am Why the Unexamined CT Can Be Very High Dose Kalpana Kanal, PhD
9:00am Low Dose CT Technique William Shuman, MD, FACR
9:20am Low Dose CT in the Abdomen: Practical Applications Carlos Cuevas, MD
9:40am Low Dose Techniques for Vascular CT Lee Mitusmori, MD
10:00am-10:20am Break
10:20am Low Dose CT: The Technologist’s Perspective Mario Ramos RT,CT
10:40am Low Dose Cardiac CT — Coronary Arteries, Whole Chest, and Beyond Kelley Branch, MD
11:00am Educating Patients about Radiation Janet Busey, MS
11:20am Low Dose CT in the Acute Care Setting Martin Gunn, MD
11:40am The Future of Low Dose CT Paul Kinahan, MD
12:00-12:30pm Questions and Panel Discussion
Adjourn

Hope to see you there!

Is Government Regulation Necessary for CT?

A recent editorial in the Journal of the American Medical Association took the position that the best course of action to address the issues of CT overutilization, quality control and training would be government regulation, according to an article on HealthImaging.

In the original editorial, authors David J. Brenner, PhD and Hedvig Hricak, MD reported that “the radiation dose in America has doubled over the past 30 years, and medical imaging contributes half of the dose to the U.S. population,” as stated in HealthImaging. They argue that only through national legislation will we be able to ensure lower CT radiation dose and an improvement in overall safety to patients undergoing CT exams.

Actually, there are very good resources available now for deciding appropriateness and supporting referring physicians, such as the American College of Radiology’s (ACR) appropriateness criteria or commercially available, evidenced-based decision support programs which are built into electronic order entry systems.

Rather than have the FDA develop a new agency, perhaps wider and better application of these existing resources and regulation through societies of experts (like the ACR and the Radiological Society of North America) might be impactful.

Debating the Cumulative Radiation Dose Theory

Despite the attention being given to the cumulative CT scan radiation effect and the buzz surrounding risks of repeat CT scans, one leading expert is disputing the theory.

As reported in Diagnostic Imaging, Richard Morin, Ph.D, chair of the American College of Radiology’s safety committee says, “There is no radiation biology to demonstrate CTs are additive in any way.”

Morin uses a driving analogy that relates probability of an accident to the number of miles logged by a driver, but notes that there is not a certain mile threshold, like 200 miles, that would trigger an accident.

I like the driving analogy and used it in my recent post Measuring Risk: Driving vs. CT. Driving is something that most of us can relate to, and therefore the numbers are more meaningful, so I’ve tried to quantify it even further.

Here’s how I like to look at the risk: The risk of dying from a cancer induced from a CT of the abdomen and pelvis in a middle aged male is similar to the risk of dying in a car accident if you drive 36,000 miles – both are about one in 2000.

The debates over cumulative dose theory will continue, and so I feel it’s important to explain the risks in ways people can understand – so that they don’t turn down any life-saving exams out of fear or misunderstandings.

While Dr. Morin explains that there is no way to figure out whether a person developed cancer due to radiation, a carcinogen or chance, he does say “it’s important that the right test is ordered at the right time.”  I’ll add that it’s always a good idea to look at lowering the CT dose, too.

And while the effect of cumulative dose from multiple exams is unproven, we really must take the most conservative position when it comes to public health and assume the effect is cumulative.

Keeping Patients Up To Date

Part of doing research at an academic institution requires consenting patients to participate in research studies involving radiation exposure. I’m always amazed at the number of patients that have no idea that their clinically ordered procedure involves radiation, because nobody took the time to explain this. Patients read the papers, they watch the news and they are fully aware of the ongoing media frenzy surrounding radiation in medicine. Patients often ask me, “Is it safe?” While the risk/benefit debate about ionizing radiation exposure continues to be a hot topic in the medical community, we must not forget to keep our patients in the loop.

Educating patients that radiation often is necessary in medicine can be extremely challenging – but it is more critical now than it has ever been. Talking to a patient about radiation exposure is much different than talking to your radiology colleague, especially when the true incremental risk to patients from medical radiation is still under much debate. There needs to be a coordinated effort at each institution to make sure that patients are receiving correct and accurate information about radiation. The imaging community needs to work together to devise websites and reading materials that educate the public about radiation exposure and risks versus benefits of imaging with radiation.  Everyone involved in patient care must understand radiation, radiation risks, alternatives to scanning and what techniques are used to keep dose as low as possible.

Resources on explaining radiation to patients:

1. RadiologyInfo.org

2. “How to Explain Radiation Risk” from the Washington State Department of Health

3. Wanzhen Zeng’s “Communicating Radiation Exposure: A Simple Approach

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.

New Algorithm Provides Lower Radiation Dose, Better Image Quality

At the recent International Society for Computed Tomography (ISCT) meeting in San Francisco, studies were presented showing that CT scanning with a new algorithm, called model-based iterative reconstruction (MBIR), could offer better image quality and lower radiation dose than scanning with an adaptive statistical iterative reconstruction (ASIR).

According to AuntMinnie.com, “researchers claim that MBIR outperforms previous efforts to maximize the utility of low-dose CT exams, with researchers reporting excellent image quality and enhanced lesion conspicuity.”

University of Washington is one of the international sites for the multi-center trial of MBIR. My colleague, Paul Kinahan, was one of the two scientists who reported on MBIR images at the ISCT meeting.

We are very impressed with the technique here – it may someday result in a further huge dose reduction for CT. At this point it is in early stages of development and assessment of its clinical impact has not yet begun. But it looks very promising!

Standardization Protocols for CT Would Help Lower Dose, Increase Patient Safety

Last month, the American Association of Physicists in Medicine (AAPM) hosted national Dose Summit that focused on the need for standardization protocols for CT scanning, which would help to ensure patient safety and lower associated radiation risks during CT exams.

According to an e! Science News article, summit attendees included some of the world’s leading experts in CT imaging. Organizer Cynthia McCollough, Ph.D., said the summit “achieved its goal of identifying several issues that need to be dealt with by the medical imaging community in order to address the safety concerns of patients at U.S. hospitals and clinics.”

This summit also made progress in “developing consensus CT protocols and making them freely available via the Internet to hospitals and clinics across the United States.” CT protocols (or “imaging parameters”) define how equipment is used for certain procedures.

In my opinion, standardization of protocols is a powerful way to lower CT dose. In a recent study published in the Annals of Internal Medicine, adjacent hospitals in the San Francisco Bay area had a 13-fold difference in CT exam radiation dose for similar studies done for similar indications. The difference was all in the technique parameter selection.

With standardized protocols, groups of radiologists can get together to study how to do various types of CT exams with the lowest dose but yet still producing good diagnostic information. Once they agree on CT technique parameter selection with low dose as a goal, they can all use the same protocols and practices. This can dramatically lower the dose to a patient population – through standardization on best practices in CT.

Discussing the Benefits of Low Dose CT Scans

Radiation is part of nature. We’re all exposed to radiation every day in very small amounts. But the amount of radiation being used for medical diagnosis has been increasing over the last 20 years or so – to a point where it is now raising new concerns about CT scan risks. In fact, the use of CT has increased over the last decade to the point where we’re now doing around 60 million CT scans a year in the United States.

So what does this mean for patients?

What other options are available to minimize the effects of CT scans?

How can patients go about trying to make smart decisions about the risks and benefits of CT scans?

Last October, I took part in a Webinar for Patient Power with medical physicist Dr. Kalpana Kanal that addresses these questions and more – touching on radiation dosage and risk, new technologies, and techniques for limiting exposure.

>watch the webinar

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.