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.”
Guest blog by Kalpana M. Kanal, PhD, Director of Diagnostic Physics Section and Professor in the Department of Radiology at University of Washington
In a recent article published online1, the authors state in their introduction that radiation dose risk is cumulative and an increasing number of patients are undergoing multiple follow-up procedures at regular intervals. Is cumulative dose of concern in patients who have repeated scans? The jury is still out on this question. There is support for tracking cumulative dose2 as well as thought that cumulative dose should not be given any importance when making decisions about individual patients3, 4.
Radiation risk is based on the linear no-threshold model which states that all radiation exposure carries some risk but these need to be weighed against the benefits of the radiation exposure. This linear relationship implies that irrespective of which CT scan a patient is receiving, the absolute risk is the same. There is no increase in sensitivity from the increasing dose received from repeated CT scans, only an accumulation of probability. The linear no-threshold model would break down and not make any sense if there was an increase in sensitivity from repeated scans.
Consider the analogy of driving to work every day which has a risk of a fatal automobile accident associated with it. We do not keep track of the number of times we have driven in the past and its influence on whether we drive tomorrow or not. Similarly, as far as medical decisions are concerned, cumulative dose should not play a factor in deciding if a CT scan should be ordered or not. The benefit of getting the CT may far outweigh the risks. Also, individual risks are hard to quantify as all our risk models are based on large population data.
It is very important that we do not misuse the patient history information about previous scans to influence our medical decision today. Educating the physicians and the public on this is paramount to avoid such misuse.
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.
Pictured above: UW Medicine Radiology Chief Resident Jennifer Favinger and Resident Derek Khorsand consulting with patients at the Seattle/King County Clinic
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.
Here on this blog I often talk about the importance of patient education and awareness, as it relates to CT scans, radiation dose and cancer risks. Informed patients are smart patients! To that end, I wanted to share with you an interesting resource I recently came across: a “radiation risk calculator” sponsored by the American Society of Radiologic Technologists.
According to the site, the purpose of this (free) tool is to “calculate your dose and estimate cancer risk from studies including CT scans, x-rays, nuclear scans and interventional procedures.” I think this is good for patients, if combined with counseling about the meaning of the numbers.
I always say: the more info, the better – as long as it is understood appropriately. Remember too, that a 1 in 2000 risk of causing cancer means a 1999 in 2000 risk of not causing cancer…
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.
A recent study I came across found that patients in emergency departments have very high confidence in CT scans and technology. Furthermore, it seems as if patients get increasingly more confident that they’ll get a proper diagnosis the more testing they have done. But compounding this is another finding of the study: most patients’ understanding of radiation exposure is poor.
The key to this discussion is the concept of appropriateness. What that means is the balance between cost, risk, and the chance that a test may provide valuable information, which impacts on therapy, outcome of the disease process, or peace of mind (which has value, too).
As this study points out, patients have confidence in CT, but that confidence does not translate directly to appropriateness. Risk of CT radiation is hotly debated, but that too does not equate with appropriateness by itself. And cost effectiveness is just one component of the stew that is appropriateness.
So, given all those limitations, how do we get there? Answer: use the radiologist – equipped with powerful support tools – as a consultant to find the balance that optimizes appropriateness. The radiologist is an epicenter of knowledge about radiation risk, cost effectiveness, and the potential positive impact of a CT. Add to that support from a decision support program – which is a compilation of all knowledge in these areas – and you have the best path to appropriateness in this complex world of high-tech imaging.
An article that was published after RSNA talks about a study that found that CT scan radiation risk in patients may be overblown. However, at the close of the article, it says that longer-term, more in-depth study is needed. Until then, physicians and patients still need to weigh the risks and benefits of CT.
For patients to both be informed and to understand (comprehend) risk related to radiation is very challenging. This is because there are few comparables in normal daily life which can clearly quantify extremely small risks. The one I like the most is: 10 mSv give you a risk of dying from an induced cancer of about 1 in 4000. Driving a car in the USA for 80,000 miles over 3 years also gives you a risk of about 1 in 4000 of dying in a car accident.
Now, both a CT scan with 10 mSv and 80,000 miles of use of a car bring certain benefits. But they carry a risk of dying of 1 in 4000. What do you think of that risk/benefit ratio? Would that ratio make you stop driving a car?
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.