As imaging studios have markedly increased in the past two decades, so has the concern among some clinicians and media surrounding radiation dose management. With new state legislation and the implementation of institutional regulatory programs, are these efforts to report and track radiation dose measuring up?
Laying down the law
Among the 50 states, California, Texas and Connecticut stand out for their legislative endeavors in mandating radiation dose reporting. California was first in 2010 in requiring the recording of radiation dose on all patient records. They also established specific dose thresholds and the reporting of surpassed thresholds to state authorities within five to 15 business days.
In Texas, extensive dose regulations have been passed by the Department of State Health Services, extending beyond CT to include fluoroscopy regulations as well. Radiation protocol committees must be developed and their own standards must be met. While these three states are the most prominent in the dose reporting discussion, others are expected to follow suit as radiation safety concerns persist.
Attempting to follow the Golden State’s lead, Connecticut saw Raised Bill 6423 introduced in the state’s General Assembly in early 2013. The bill would require the same dose regulations as California, while also mandating annual CT scanner inspection to ensure that displayed dose has not deviated more than 20 percent from the scanner’s actual measured dose. Originally slated for an October 2013 instatement, the bill stalled in the hearing committee.
Beyond state legislation, hospitals and imaging centers nationwide have begun to adopt regulatory programs to ensure patient safety. “You can only effectively act on a problem if you can capture data that directly exposes the issues,” remarks Aaron Sodickson, MD, PhD, of Brigham and Women’s Hospital (BWH) in Boston. Sodickson and colleagues have developed extraction tools to obtain and record radiation exposure data for CT and nuclear medicine.
The generalized radiation observation kit (GROK) is one of the tools that has been produced at BWH. GROK locates and gathers volume CT dose index and dose-length product information from a DICOM image archive. Dose screens also are transformed into text for analysis by the tool. The open-source informatics toolkit exemplifies the feasibility of creating large-scale anatomy-specific radiation dose repositories through the use of existing archival information.
“An important distinction needs to be made,” says Sodickson. “Nobody is accurately recording patient dose. Rather, we are recording CT technique factors and x-ray tube output metrics. A lot more calculation is needed to turn these values into meaningful patient specific doses.”
Perl Automation for Radiopharmaceutical Selection and Extraction (PARSE), another software extraction tool, was conceived by Ichiro Ikuta, MD, of BWH, and colleagues. PARSE extracts exposure data from existing nuclear medicine report archives, enabling organ dose calculations for longitudinal patient-specific dose monitoring. PARSE also is capable of generating organ dose heatmaps to visualize organ dose accumulation.
Medical professionals at Emory University in Atlanta have been performing dose tracking through the use of the American College of Radiology’s (ACR) Dose Index Registry (DIR). They’ve been using the DIR to track dose as an average across their institution and at an individual scanner level as well.
“We have shown that we’ve reduced radiation dose levels across the institution,” says Phuong-Anh Duong, MD, chair of the CT Quality and Safety Committee of Emory Radiology. “Our dose levels have fallen below the average benchmarks. It’s been successful, but we can certainly do more and we are trying to do more.” Duong estimates that they have aggregately reduced dose by 30 to 50 percent depending on the scanner.
At Intermountain Healthcare in Salt Lake City, a joint venture between radiology and cardiology began several years ago to handle radiation dose tracking. “We developed mechanisms to track patients’ cumulative radiation dose for four high-dose procedures: CT, nuclear cardiology, cardiac catheterization labs and corresponding interventional procedures,” says Keith White, MD, medical director of Intermountain’s Imaging Services. “This is a very difficult and complicated process to go through. It’s simple to say but it is a difficult number to come by. This is an ongoing process.” So far, Intermountain has made substantial improvements in radiation dose management and has reduced dose across the board by 8 percent. After two years, a major impact has been seen on CT orders in their pediatric community.
The IT factor
Creating a mechanism to track and report effective radiation dose requires comprehensive IT capabilities. “You need appropriate connectivity to multiple sources, such as PACS or the CT scanners, and either a local database infrastructure or an external dose registry such as that of the ACR. Personnel and other IT resource investments are needed to make a program robust,” explains Sodickson.
White details the complexity behind dose monitoring technology, explaining that the methodology to handle dose in the four modalities at Intermountain is different for each. The most challenging is CT. A phantom calibrates the scanner estimating of how much radiation is emitted for each scan. When a patient is scanned, the scanner reports an estimate of how much radiation was delivered to the body. “This number does not take into account what the body absorbed or how sensitive the body parts or organs involved are to radiation,” says White. Further estimation that takes into account the body part scanned, the age of the patient and the size of the body is required to produce the final estimate of effective dose, which is measured in millisieverts (mSV).
Brent Little, MD, of Emory University points out that having radiologists in the feedback loop can be difficult. “Reducing the dose may slightly alter the appearance of scans but need not influence the diagnostic quality,” Little says. “Radiologists need to get acclimated to seeing a different image.” Little also cites the difficulty of getting protocol drift—which occurs when adjustments are made to scanners that do not have standardized protocols—under control after dose modifications. “This is made easier with the help of a centralized committee that’s concerned with dose tracking,” he adds.
At Intermountain, radiation dose tracking and reporting has not borne out immediate engagement from patients and has not been easy for referring physicians to embrace or understand. “There hasn’t been a massive turnaround in understanding dose. That’s going to take years of ongoing effort to educate doctors and patients,” comments White.
In the future, these experts hope that dose monitoring is incorporated into decision making for both referring physicians and patients. Sodickson explains that CT techniques need to vary greatly across patients of different sizes in order to maintain diagnostic image quality. Sodickson continues, “Tremendous advances in dose tracking have been made in the last few years with the support of many institutions and the addition of new functionalities by CT manufacturers. Though continued gaps in knowledge remain to be closed, tight collaboration between manufacturers, radiologists, technologists and medical physicists will produce continued advances in this area.”