SCOAP Community Speaks Up: Radiation Safety

Radiologists at University of Washington have asked “What is SCOAP doing about reducing radiation exposure for WA State patients having surgical care?” 

In the March 2009 SCOAP Box, surgeons at Kadlec Hospital asked, “Why does it seem that SCOAP wants everyone to get a CT scan given recent evidence of radiation’s effect over time?”  We responded at that time that SCOAP’s focus is not on getting more CT scans but on getting more accurate scans and where the accuracy of ultrasounds is acceptable, increasing the use of ultrasound.  Since then, SCOAP data (see figure) shows that the relative use of CT and US scans has stayed about the same over SCOAP’s 5 years and that US accuracy remains highly variable across sites.

Consensus is growing that efforts are needed to minimize radiation exposure from CT scans. The National Academy of Sciences National Research Council[1] did an extensive review of the literature related to the health risks of radiation and found that patients who received radiation doses of a single CT scan were at increased risk of developing cancer. Surgical patients often receive multiple CTs, and their risks are even higher. A NEJM article[2] found that the risk of cancer from a single CT scan could be as high as 1 in 80. Radiation doses are not consistent across hospitals, and doses of radiation may be much higher at some centers than generally quoted. A study [3]describing radiation dose associated with the 11 most common types of diagnostic CT studies, performed on 1119 adult patients at 4 San Francisco Bay Area institutions, found that radiation doses between the institutions as well as within the individual hospital were extremely variable. Within each type of CT study, effective dose varied significantly within and across institutions, with a mean 13-fold variation between the highest and lowest dose for each study type.

Given these disturbing findings about unnecessary radiation exposure, there are two major recommendations to improve the safety of CT scans:  1) lower the radiation dose of routine CT scans and 2) use CT scans only when necessary.  The collection, standardization, and reporting of radiation dose information is currently limited and fragmented in the documented record.  More importantly, there are no clear standards or oversight for radiation dosing. For our patients this represents an opportunity for improved quality. As in many other areas of surgical quality improvement, SCOAP should be able to lead the way on radiation safety.  Beginning in January 2011 SCOAP will collect data on the Dose Length Product (DLP) for CT scans for non-elective appendectomies. DLP is a measure of the total radiation exposure for the whole series of CT images. The DLP is directly related to patient risk and may be used to set reference values for a given type of CT examination to help ensure patient doses at CT are as low as reasonably achievable. Tracking this information will help SCOAP hospitals work toward the goal of providing CT scans with the same quality but decreased radiation.  SCOAP is trying to foster partnerships between radiologists and surgeons to obtain and use these data for QI.

 We’ve also heard these questions from SCOAP surgeons:

 What strategies can our hospital use to decrease radiation exposure?

There are several recommendations for radiology departments to reduce radiation exposure. Some are simple – don’t scan parts of the body that are not needed; use shielding and train staff to monitor dose in order to make adjustments if doses are too high. (The latest generation of scanners provides automatic exposure-control options.)  For many types of CTs, the radiation dose can be reduced 50% or more without reducing quality[4], although it is true that as the radiation dose decreases, the relative “noise” in CT images increases, and this can limit the image quality.  Accepting more noise does not mean losing diagnostic power, as there are ways for the radiologist to compensate. SCOAP has assembled a group of experts who are available to come to any hospital in the state to hear more about this topic. Specific guidelines in how to lower dose per CT scan by up to 40% without compromising diagnostic power are available at CT.com or xrayrisk.com.

Are there special considerations for pregnant women and children?

Fetal exposure to CT radiation in the first trimester may double the risk of childhood cancer[5], thus ultrasound is often the first choice for pregnant women. High quality ultrasound is possible, but if the ultrasound is equivocal, MRI can be done.  MRI use and accuracy was added to SCOAP in 2010, and we should have enough information about it to report back to you by the end of the year. 

 Children also merit special consideration because their tissues are more radiosensitive, they often receive a larger effective dose for a given level of radiation, and they have a longer time to develop cancers resulting from radiation exposure. Ultrasound imaging of the appendix in children has the potential for excellent accuracy[6] and within pediatric SCOAP the most recent concordance (agreement between imaging and pathology diagnosis) rate of US is 78.6% for Quarter 1, 2010. Some SCOAP hospitals have established specific protocols to avoid the use of CT scans in the diagnosis of appendicitis, emphasizing ongoing training and review to improve ultrasound accuracy, with zero negative appendectomies and no increased rate of perforation. The Alliance for Radiation Safety’s Image Gently campaign (http://www.pedrad.org) provides resources, guidelines, protocols and educational materials for radiologists and pediatricians to lessen the risks of radiation exposure.

We would like to rely more on ultrasound, but our SCOAP data shows that we have work to do to improve concordance between ultrasound imaging and the pathologic diagnosis. What do you suggest?

Many hospitals have been able to successfully address issues around ultrasound accuracy and now have a high concordance between ultrasound imaging and pathologic diagnosis, but others continue to struggle with the quality of ultrasound imaging, with a resulting reliance on CT. The average rate of concordance among US and pathology in SCOAP is only 52.1% but some hospitals have been able to set the benchmark of 88.6 %.  That high level of accuracy in ultrasound is being achieved by just a few SCOAP hospitals, but this should be a target for all hospitals.  Accuracy and quality for ultrasound scans depend on the skills of the sonographer and there are best practices in sonography that can increase diagnostic accuracy and these can be shared between better performing SCOAP sites and others that are struggling with this metric.  SCOAP can help connect hospitals so they can share best practices.  It’s key that radiologists and sonographers at each SCOAP hospital know about benchmarking through SCOAP and that they be engaged in the process of improving accuracy. 

Technical improvements in US may not be enough.  Use of ultrasound imaging can only occur when skilled staff are present. Some smaller hospitals do not have 24-hour access to ultrasound.  Surgeons may be reluctant to hold patients in the ED and “wait for the day shift,” because they are concerned that delay may increase the risk of perforation.  Furthermore, ultrasound may not be the first imaging choice for all patients – patients who are obese may not be good ultrasound candidates. We encourage SCOAP surgeons and hospitals to engage radiologists in a QI activity surrounding diagnostic accuracy.  This is not commonly done, and we may be breaking new ground at some hospitals.

Is imaging even necessary in patients with presumed appendicitis?

SCOAP has been following the use of imaging in the diagnosis and treatment of appendicitis since we started. Initially, metrics focused on teasing out the use of either ultrasound or CT scans as part of the diagnostic work-up to determine whether the use of imaging was a factor in the incidence of negative appendectomy, whether the imaging impression was concordant with pathologic diagnosis, and also to learn whether use of imaging was related to a decrease in adverse outcomes such as perforation.  SCOAP also has gathered data on the use of imaging in women of reproductive age, where differential diagnosis is more complicated.   For women of reproductive age, the rates of negative appendectomy are VERY HIGH when no US or CT are used. Our experience with SCOAP data encourages the use of these tests among women of reproductive age. The use of imaging seems to matter less among young men but the rates are so low that it’s hard to assess the value of imaging in this.

Because of your hard work, we have seen the rate of negative appendectomy (among women) drop from 11% to 1.8%. Now we are adding a new and important piece to the puzzle to reduce radiation exposure without impacting quality outcomes. 

Thanks for the questions and for all you do to make SCOAP a success!


[1] National Council on Radiation Protection and Measurements. Ionizing Radiation Exposure of the Population of the   United States. 2009. NCRP report 160. http://www.ncrponline.org/.

[2] Smith-Bindman R. Is computed tomography safe? N Engl J Med 2010;363:1-4

[3] Smith-Bindman R, Lipson J, Marcus R, Kim K, Mahesh M, et al. (2009) Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer. Arch Intern Med 169: 2078–2086.

[4] McCollough CH, Primak AN, Braun N, Kofler J, Yu L, Christner J. Strategies for reducing radiation dose in CT. Radiol Clin North Am 2009; 47:27 -40

[5] HurwitzLM, Yoshizumi T, Reiman RE, et al. Radiation dose to the fetus from body MDCT during early gestation. AJR Am J Roentgenol2006; 186: 871–876.

[6] Dilley A, Wesson D, Munden M, et al. The impact of ultrasound examinations on the management of children   with suspected appendicitis: A 3-year analysis. J Pediatr Surg. 2001;36:303-308.

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