Radiation Safety Law to Expand, But Did It Miss The Mark?

September 25, 2014

Other states are expected to adopt variations of California’s radiation safety law, but is the law really protecting patients?

For four months after California’s radiation safety law took effect, radiologists with Pomona Valley Hospital Medical Center verbally dictated dose information from CT scans into each patient’s radiology report.

The manual dictation wasn’t difficult. “But whenever you have to do the same repetitive copy task over and over again, it’s not the best use of any radiologist’s time,” said Johnson B. Lightfoote, MD, medical director of Radiology at Pomona Valley. 

Pomona Valley has since contracted with a third-party vendor who provides software that automatically uploads the dose information directly into patient radiology reports in compliance with the California law, which took effect July 1, 2012.

The software is expensive enough that radiologists at smaller practices continue to dictate the numbers - a task Mark Alson, MD, with Sierra Imaging Associates, described as “extra time, but we’ve got it down at this point.”

He added: “If you spell out the numbers to the nth degree, it would be very cumbersome, but the law doesn’t necessarily require that; just that you give the numbers.”

Going International
Either through manual dictation or third-party software, both practices are in compliance with the law - an undertaking radiology practices in other states may soon confront.

Debbie Gilley, government relations specialist with the American Association of Physicists in Medicine, said three states - Arizona, Massachusetts, and Texas--already have regulations in place that are similar to the California law.

Results of a survey conducted in the fall of 2013 identified six states also developing regulations and four other states exploring the possibility of introducing regulations.

More are likely to follow suit, said Lisa Bruedigan, chair of the Conference of Radiation Control Program Directors’ Healing Arts Council.

“I don’t think it’s going to explode,” she said.  But with a new chapter due out this fall as part of the Conference’s suggested state regulations (SSRs), states will have to make only minor edits to the suggested rules rather than re-write regulations from scratch.

Section F of the SSR’s Medical Diagnostic and Interventional X-ray and Imaging Systems consists of portions of the California law and Texas rules, along with input from other resources, “massaged together for states,” Bruedigan said, describing the guidelines as “meaningful but generic enough for other states to adopt.”

Variations of the California law may even go international, she said, noting that the government of South Korea spent three days in Texas and California asking about CT rules, and the Atomic Energy Commission also has been bringing radiation dose reduction techniques to the forefront.

Awareness and Trends
The California law came about after reports of several hundred people receiving excessive doses of radiation during brain perfusion scans with CT.  At about that time, in 2008, a two-year-old also received excessive amounts of radiation during a CT scan in a case that ultimately was settled in court.

Among other mandates, the law requires dose reporting, which may or may not protect patient safety, especially when the overdose results from operator error - as was the case of the two-year-old.

“Having people report numbers doesn’t take care of human error,” said Alson of Sierra Imaging. 

California Radiological Society Executive Director Bob Achermann likewise disputed the necessity of the law but acknowledged certain benefits.  “Having to record the dose may raise awareness, and initiatives like the ACR Dose Registry provide tools for radiologists to compare dose parameters with their colleagues,” he said.

At UC Davis Medical Center, J. Anthony Seibert, associate chair of informatics, agreed the law has been helpful not only in raising awareness but also in pinpointing trends. 

“We’ve been able to identify situations where we lowered the radiation dose to the head, realizing that it was pretty high on scanners that did not have dose-reduction technology,” Seibert said.  “It allowed us to justify to our purchasing group why we needed iterative reconstruction software on some of our CT scanners.”

Accessible from Your iPad?
The numbers that end up on the patient chart are not the dose the patient received but the amount of radiation the machine emits, explained Scott R. Foster, informatics manager for Radiology at UC Davis.

The dose metrics are calculated as:

  •  Computed Tomography Dose Index (CTDIvol), a standard measure of radiation emitted from the machine.  It reports radiation doses calibrated for two acrylic “phantoms” -one measuring 16 centimeters in diameter for images of the head and the other 32 centimeters for the body.  Size-specific dose parameters, defined by the American Association of Physicists in Medicine, are estimated based on CTDIvol and patient size.
  • Dose length product, or DLP, the product of the length of the irradiated scan volume and the average CTDIvol over that distance.

Foster explained that the third-party dose calculator in use at UC Davis can capture the dose metrics in several ways.  Some of the CT scanners in use prepare a digital imaging and communications in medicine (DICOM) radiation dose structured report (RDSR), which reports the entire dose metric data for all series in a structured format.  This report is often not available or compatible with many informatics systems.

Most CT scanners create a DICOM Dose Protocol page with dose metric data encoded in a grayscale image as a separate series in the PACS.  While easily viewable, Foster said, optical character recognition (OCR) software must be used to convert the data to a usable alpha-numeric format for reporting.

“We need professionals and applications which help radiologists better understand and identify actionable data, and continue to improve dose,” Lightfoote said.

While dose information, including comparisons of the radiation dose from CT scans with natural background radiation, may have the added advantage of discouraging unnecessary exams, he said, on the flip side it also could also discourage patients and doctors from requesting examinations that are necessary.

“Fortunately that’s rare,” he said. “In fact, comparing CT radiation with natural background radiation may be reassuring for patients about to undergo a necessary examination.”

For older CT scanners that do not have dose metric data available, estimates of radiation dose output based upon technique factors (kV and mAs) and analysis of scan parameters can be used to estimate the dose metrics.

The flexibility of the dose calculator software at UC Davis enables extraction of dose metric data for current as well as legacy CT scanner examinations, Foster said.  Thus, improvements in dose utilization, acquisition protocols, and patient safety can be tracked and recorded.

Pomona Valley’s Lightfoote predicted that dose data direct transfer capability may become routinely embedded in applications and integral parts of CT, RIS, and PACS software.  The capability may even be accessible remotely on mobile devices like the iPad.  Direct data transfer also mitigates the error inherent in manual dictation, he said.

CT and Natural Background Radiation
Lightfoote cited additional benefits of the law, including the “statistical intelligence” that may result from studying the large volume of data that accumulates. Exploiting this “big data” could support valuable research and development projects, ultimately improving population health and risk management, he said.

While few professionals other than a qualified medical physicist would be able to estimate, based on CTDIvol and DLP, the approximate radiation dose to a particular patient, also on the horizon are technologies that will put the data into context and perspective.

Beyond Patient Dose

In addition to recording patient dose, other recommendations in the proposed SSRs by the Conference of Radiation Control Program Directors include:

  • All CT units be accredited
  • Qualified medical physicists inspect the units within 30 days of installation, every year thereafter and after potentially hazardous maintenance or repairs
  • Facilities perform phantom testing periodically to ensure the units are running correctly
  • Facilities create a CT radiation protocol committee, which includes the lead CT technologist, radiologist, qualified medical physicist, along with other appropriate personnel.

Among other tasks, the radiation protocol committee would:

  • Review existing protocol for CT, focusing on lowering the patient dose, particularly for pediatric and adult head scan protocols as well as chest and abdomen
  • Develop dose reference levels, notification alerts and alert values, such as those set by the National Electrical Manufacturing Association (NEMA)
  • Take action, such as patient follow-ups, if dose exceeds reference levels
  • Set limits on personnel able to access the CT protocols

The last bullet is intended to encourage accountability in cases of human error, explained Lisa Bruedigan, chair of the Conference of Radiation Control Program Directors’ Healing Arts Council.