The annual per-capita radiation dose from medical exposure rose from 0.53 mSv to 3.1 mSv over the past three decades.1 That’s a staggering increase of 585%. Computed tomography (CT) is the largest contributor to man-made radiation exposure. There is no doubt that the acceptance of the risks associated with radiation is conditional on the benefits to be gained from the use of radiation. Indeed, the debate todayis not whether excess radiation is bad; it is in trying to find this balance as we walk the tightrope of managing dose and getting at optimal imaging for our patients. The risks must be reduced by the application of radiation safety standards, technologies and innovations. While delivering high-quality diagnostic imaging with the lowest possible radiation dose is a desired goal, optimal radiation dose management is about much more than just low-dose devices and algorithms. Patient-centric, comprehensive radiation-dose management is about collaborative care, care coordination, interoperability, quality, safety and much more. Let us explore further.
The number of CT examinations ordered in the United States grew from 26 million in 1998 to 85.3 million in 2011.2 Medical exposure to ionizing radiation constitutes nearly half of the total radiation exposure of the US population from all sources.
While today’s growth trajectory of CT volume is not as steep as the double-digit growth experienced in the 2000s, the continued upward trend and its direct correlation to increased risk of cancer open up many opportunities to find the perfect balance as we walk the tightrope between the risks and benefits of radiation use for the appropriate reasons.
A significant part of the patient dose-management challenge in CT arises from the fact that CT overexposure is frequently not detected. In contrast to film-based radiography, where overexposure results in dark images, increasing dose in CT and in other digital imaging techniques results in images with less noise (improved visual appearance) and fewer streak artifacts, although not necessarily with greater diagnostic information. Hence, we often find that image quality in CT often exceeds the clinical requirements for diagnosis.
Determining the optimal balance is often a challenge. We rely heavily on phantom data as a basic calibration to determine radiation dose absorbed by the body during scanning. The use of anthropomorphic phantoms helps, but phantoms cannot represent the uniqueness of every patient. Data from phantom-based simulations is not quite the real thing, since most of the data is averaged and less specific. This is pushing for a level of scanning protocol optimization and dose personalization that we have not seen before. While most CT scanners do a good job of reporting the amount of energy they emit, sophisticated analysis is often required to determine what this means at a personalized level to every patient. CT radiation exposure is cumulative over a patient’s lifetime. The risk associated with a radiation dose from a single CT scan is relatively small compared with the clinical benefit of the procedure. But patients are increasingly undergoing multiple CT scans and other radiation-based procedures, which can lead to unnecessary radiation risk.
Addressing the challenges of increased CT utilization comes down to three basics areas:
In October 2010, then-California Gov. Arnold Schwarzenegger signed a new radiation patient protection law that mandates strict procedures and reporting requirements for CT scanners and radiation therapy procedures, as well as reporting of radiation overdoses to the state’s Department of Public Health. There have now been some modifications to the original law, but the intent remains the same. All CT systems must record the radiation dose on every study by putting the data directly into the radiology report or attaching the protocol page to the actual radiology report. All CT systems must be accredited through an approved modality-specific or facility-wide accreditation process. This, too, is a very positive move. Connecticut and Texas have already followed California’s example, and other states are expected to enact similar reporting requirements.Legislation in some states now require annual inspection of CT scanners to ensure that the displayed dose does not deviate more than 20% from actual measured dose. Strict rules are also being put in place around the reporting of overdose incidents, often within days of the occurrence. Whether your state mandates radiation dose regulation or not, it is clearly prudent to start developing appropriate procedures for dose monitoring and dose reporting.
The call for better innovation in radiation dose reduction continues to be heeded, and every year, we see progress in various areas. Here are some highlights:
It is one thing to have dose monitoring solutions, but another to optimally utilize the dose information. Some systems are utilizing dose information to regulate their own organizations, often tracking dose utilization by modality, by patient and even by ordering physician. Flagging patients who have had an inordinate amount of radiation over a period of time is also good practice. When this data is coupled with patient education, positive trends can start appearing in appropriate utilization of imaging services. Intelligent insights around dose metrics can also lead to competitive advantages for imaging centers and hospitals. Although the key usage of dose data is for quality improvement and regulatory compliance, patient and physician education, as well as marketing, also rank highly in how institutions are utilizing dose data.7 Arguably, the impact of optimizing radiation dose becomes greatest when radiologists work with technologists, physicists and ordering physicians in a collaborative approach towards patient-centric care.
It is imperative for radiologists to become more than “mere” diagnosticians. They need to be true physician consultants, pushing for advocacy within their hospitals and across the industry. Moving dose data upstream, to the point of order entry, is also a crucial step. Appropriateness criteria become most effective when integrated with the electronic medical record and computerized physician order entry (CPOE) systems.The appropriateness criteria need to incorporate dose information, such as cumulative effective radiation dose data, and be optimized to localized protocols guided by evidence-based guidelines, clinical best practices and contextualized patient specific data.
Enterprise Imaging—Walking the tightrope: Optimizing radiation dose management. Appl Radiol.
Dr. Shrestha is the Chief Innovation Officer at University of Pittsburgh Medical Center, Pittsburgh, PA, and Executive Vice President of UPMC Enterprises. He is also Chair of the RSNA Informatics Scientific Program Committee; a Founding Member of the Executive Advisory Program, GE Healthcare; a member of the advisory boards of KLAS Research and Peer60; a member of the Board of Directors of the Society for Imaging Informatics in Medicine; a member of the boards of Pittsburgh Dataworks and Omnyx Inc., and a member of the Applied Radiology editorial board.