Quality patient care involves ordering “the right exam at the right time with the right radiation dose.” It’s a mantra radiologists know well. Recently, a growing number of
publications have added nuance to that phrase — raising concerns that patients who have a high cumulative exposure to radiation be directed to modalities that don’t use it, such as US.1-3 The joint statement is also endorsed by the RSNA, the American Society for Radiation Oncology, the Association for Medical Imaging Management, the Society of Cardiovascular Computed Tomography, and the Society of Nuclear Medicine and Molecular Imaging.
“Dose information tracked in EHRs is not standardized — or even universally accepted,” says Mahadevappa Mahesh, MS, PhD, FACR, chair of the ACR Commission on Medical Physics and professor of radiology at Johns Hopkins University School of Medicine. “Imaging history is useful to doctors as they work with patients to determine the best care, but still-evolving dose estimates should not be used to deny patients’ imaging exams prescribed by their doctors.” The Bulletin caught up with Mahesh to learn about how using cumulative dose as a decision tool could affect patients.
What does the new joint statement mean for patient safety?
We are starting to see more and more publications discuss adding together a patient’s past radiation doses to create a cumulative dose that would influence patient treatment and affect decision-making on future studies for the patient. These publications have caused some alarm, because we believe previous dose history should not affect whether a patient undergoes an imaging exam. Guiding decisions in this way can have a lot of unintended consequences, particularly if regulators or health insurance companies set arbitrary limits on those doses and deny care based on a patient’s dose history. We released the joint statement because we thought a message coming from the ACR, the AAPM, and the Health Physics Society would amplify our concerns.
That said, the statement applies to tracking a patient’s stochastic, or probabilistic, risk only. It doesn’t apply to organ-specific doses for evaluating the onset of deterministic effects, such as skin injury tissue reactions.
How might physicians who use cumulative effective dose metrics to guide their decisionmaking hinder patients from undergoing clinically necessary exams?
Radiologists and other physicians should base their decisions on evidence-based guidance and indicators, such as Appropriate Use Criteria and the results of prior tests rather than a historical radiation dose estimate. Effective dose is not a measure of risk to an individual, but a radiation protection quantity that estimates detriment to an entire population — you can’t use it to assess a patient’s individual risk. If a patient receives a head CT, and later receives an abdominal CT, examining cumulative effective dose doesn’t make sense — because each study was done on different parts of the body.
Many practices are also using radiation dose management software in their EHRs, which sometimes adds whatever numbers are available to it to create a cumulative effective dose; however, we know this number is not standardized or universally accepted. Also, because no standards currently exist with which to compare cumulative effective dose values, having a random number with little context can mislead and hinder clinicians from ordering the most necessary studies — which could mean greater costs to patients. If a patient has passed the number deemed appropriate for cumulative dose, a physician might substitute a test with something else that does not use radiation. But modalities vary widely, and that test could vary in effectiveness for a particular need, time, and supplies available to undergo the exam, as well as cost to the patient.
Are there other useful applications for dose monitoring software?
Radiation dose index monitoring software is extremely useful for quality assurance. Practices can measure their numbers against regional and national values like those in the ACR Dose Index Registry® to fine-tune protocols to ensure they are performing at reasonable dose values. Analyzing the dose data collected by these tools can also help us identify exam protocols that might benefit from a second look, and outliers can help identify where clinical processes can be improved.
Should radiologists still monitor radiation dose?
Radiologists should be working with medical physicists to ensure that every modality is operating optimally and that every machine is using appropriate radiation doses for each patient and exam type. It is important that the amount of radiation used is dictated by the image quality needs of the radiologist and clinical task. The point of the joint statement is not to diminish the role of medical physicists and RTs in optimizing radiation dose, but that dose history should not be used to guide decision-making in imaging.