RSNA13: Dubious About Dose
When it comes to the subject of radiation dose and patient safety, dubiosity continues to be the prevalent state among U.S. radiologists, or so it seemed in session rooms at RSNA. The mention of dose in a scientific session almost always comes with a qualifying remark that boils down to this: The precise quantification of risk has yet to be determined by science. Vendors, on the other hand, continue to drive down dose through the introduction of low-dose protocols, improved image processing, and technical tweaks. David Sloop at Toshiba Medical Systems showed the newly FDA-cleared Dose Tracking System on the company’s Infinix-X vascular system. The tracking system measures skin absorbed dose as compared to the more prevalent air kerma method and provides a color-coded visual display (blue, green, yellow, red) for the physician. A number of systems to track patient cumulative dose were also on display: Radimetrics at the Bayer booth, DoseMonitor at the PacsHealth booth, and, reportedly, GE introduced a new system, DoseWatch. At the Sectra booth, Jeremy Koscielny showed that company’s web-based PACS-agnostic system, DoseTrack, which grabs data from the DICOM Dose Structured Report or DICOM headers via Modality Performed Procedure Step; can be configured to support national or local dose standards; utilizes the 25 virtual phantoms developed through Monte Carlo simulation at the Rensselaer Polytechnic Institute in Troy, NY, and the University of Florida; and can export data to the ACR Dose Index Registry. What the system can do with the data is an important distinction, Koscielny says. In addition to filing data to the ACR’s national registry, users can benchmark to local and national levels, set thresholds to trigger email alerts, and dig in by modality, technologist, machine, and time period. Mike Battin, CEO of PACSHealth which markets DoseMonitor, provided a clear and simple argument for the tracking of patient dose: An analysis of seven hospitals in a single multi-facility system revealed wildly varying CTDIvol values for CT head wo contrast. A Contrarian Perspective Many of these dose-tracking providers report a great deal of interest in the tools, but a lack of will when it comes to implementing. This is less true in California, where law requires that dose be recorded in a patient’s report, Texas, where providers must monitor CT dose, and Connecticut, where dose reporting legislation is pending. Nonetheless, the grumble level regarding compliance (which can be quite cumbersome) is relatively high. In an RSNA session on the Legislative Impact of CT Dose Reporting Requirements, Jonathan Breslau, MD, practice president at the Radiological Associates of Sacramento, provided a distinct counterpoint to the grousing as well as some thought leadership on the subject of radiation exposure in medical imaging. “There are places where we can have debates on ‘are we really causing cancer’, but I think we need to treat the public perception as reality,” he says. “Radiologists need to be the shepherds of where radiation exposure is going, radiologists need to own this issue.” Breslau, whose practice was recently acquired by Sutter Health, says that as cumbersome as compliance can be, he is glad that the reporting of dose was legislated. “We have an important tool, a tool that saves lives, but we have to be responsible for this,” he says. “The public is the ultimate constituency. It’s an opportunity, not a pain.” Due to the moral implications of unnecessarily exposing patients to radiation risk, quantifying radiation risk using the gold standard in medicine—a prospective patient trial—will never happen, experts agree. If radiologists find themselves getting tripped up by the fuzzy science issue, perhaps approaching the issue as basic housekeeping is the way to go.