Survey Says: Physicians Not Doing Enough to Lower Stress Test Radiation Exposure
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Health care providers are doing a poor job putting modern radiation-limiting measures into practice when it comes to nuclear stress testing, and many practitioners exhibit insufficient knowledge regarding radiation safety, according to survey results appearing online May 6, 2013, ahead of print in JAMA Internal Medicine.
For the research letter, Andrew J. Einstein, MD, PhD, of Columbia University Medical Center (CUMC, New York, NY), and colleagues sent a survey to members of the American Society of Nuclear Cardiology (ASNC) in 2011 to assess practitioners’ knowledge and current practices impacting patients’ radiation exposure from nuclear stress testing.
Out of 374 ASNC members who received the survey, 73 (19.5%) responded, comprising 46 physicians, 23 technologists, and 4 “other.”
Stress-only Imaging Seldom Used
The median annual number of nuclear stress tests performed for those with volumes greater than 0 (n = 59) was 1,200. Rest-stress Tc-99m was the most popular, used in 58% of studies and 40 labs (89%), followed by dual-isotope imaging (15.6% of studies, 10 labs). Stress-first imaging, which can decrease radiation exposure by 75%, was used in only 7.3% of studies, all reported by 6 respondents (13%), with 4 from high-volume labs.
Roughly half (51%) of respondents (n = 37) reported using 1 or more approach to reduce radiation exposure, with no single approach used in more than 30% of studies. The most common approaches were:
- Reducing injected radiopharmaceutical while increasing imaging time (33%)
- Stress-only imaging (23%)
- Newer camera systems (20.5%)
- Changing radiopharmaceuticals (19.2%)
No single method was reported to be used in more than 13% of studies in the previous week or in more than 15% of labs.
Twenty-four of 48 respondents (50%) reported using appropriate use criteria to track the appropriateness of stress testing, with no difference among type of practices (P = 0.76) or tertiles of nuclear stress test volume (P = 0.66).
Most Respondents Underestimate Dose
Of 46 respondents, the majority (87%) reported having read at least 1 ASNC statement on radiation safety. Of the 73 individuals who completed the survey, 36 (49.3%) responded to the question asking how many posteroanterior chest X-ray exams would be equivalent to a single-day rest-stress Tc-99m X-ray exam. A range of 350 to 650 X-ray exams (ie, 7-13 mSv) was considered a reasonable correct answer.
Of the 36 respondents, over two-thirds (n = 25; 69.4%) underestimated the dose. Twenty-two physician respondents omitted answering this question, and of the 24 physicians who did respond, answers ranged from 1 to 1,050 X-ray exams. More than two-thirds (71%; n = 17) of physicians underestimated the dose, including 14 who answered ≤ 166 X-ray exams. Three overestimated, and only 4 answered correctly (17% of respondents, 9% of all physicians surveyed).
The survey makes clear that “dose-reduction approaches have largely not been assimilated into everyday practice,” the authors conclude. In particular, they note, “the 7.2% rate of stress-only imaging represents a missed opportunity to skip unneeded rest imaging in many patients,” while “The 15.6% rate of dual-isotope testing is unacceptably high.”
Dr. Einstein and colleagues also lamented that although the majority of physicians (93%) reported having read radiation safety statements, “only 9% could correctly characterize the radiation burden to patients from the most common NST protocol, a figure sizably lower than the proportion of imaging physicians correctly describing radiation in other contexts.”
The authors suggest specific goals to improve the radiation safety for the 10 million US patients undergoing nuclear stress tests annually:
- Bridging gaps between physicians’ exposure to radiation safety literature and actual knowledge
- Increasing use of low-dose stress-first imaging while decreasing dual-isotope imaging
- Promoting wider integration of appropriate use criteria into clinical practice
- Fostering validation, use, and affordability of advanced technologies permitting reduced administered activity
In an editor’s note, JAMA Internal Medicine editor Rita F. Redberg, MD, MSc, of the University of California, San Francisco (San Francisco, CA), observes that the survey shows definite “room for improvement,” adding that numerous radiation minimization strategies appear underused. Due to the high number of nuclear stress tests each year, “a profession-led campaign to decrease radiation exposure would maintain the benefits of testing but lower the rate of cancers due to these procedures in the next decades significantly,” she urged.
Survey Results ‘Abysmal’
Stephen Balter, PhD, also of CUMC but not affiliated with the study, indicated that the poor use and knowledge of radiation-sparing practices is not surprising. “[The authors] surveyed labs of people who belonged to the nuclear cardiology society. These should be the most educated, and the results are abysmal,” he told TCTMD in a telephone interview.
Dr. Balter attributed the results to an attitude among physicians of: “This is the way I always did it, and why try to fix something that’s working?” He added, though, that “with all the public outcry [over radiation safety], one would have hoped that someone was paying attention.”
He added that in the future he expects increased pressure from medical societies for practitioners to increase their use and awareness of radiation-minimizing practices. “If the average physician understood the difference in the radiation dose between the rest-stress and the stress-only method, it would motivate a good fraction to change their practice,” Dr. Balter said, adding that the effects on cancer rates would be substantial.
“With the models [used in the study], if you cut the radiation by 75%, you cut the nominal cancer rate by about 75%,” he said. “Ten million studies is theoretically a lot of cancer, and if you change the strategy, you can make that a lot less, and that’s got to be good for society.”
Sources:
1. Einstein AJ, Tilkemeier P, Fazel R, et al. Radiation safety in nuclear cardiology—current knowledge and practice: Results from the 2011 American Society of Nuclear Cardiology member survey. JAMA Intern Med. 2013;Epub ahead of print.
2. Radiation minimization strategies for medical imaging. Editor’s Note. Redberg RF. JAMA Intern Med. 2013;Epub ahead of print.
Disclosures:
- Dr. Einstein reports receiving research grants from GE Healthcare, Philips Healthcare, and Spectrum Dynamics; receiving a speakers fee from Spectrum Dynamics, and serving as a consultant to the International Atomic Energy Agency and Radiation Effects Research Foundation.
- Dr. Balter reports no relevant conflicts of interest.
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