It takes teamwork + tech to optimize CT dose

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 - reduced coverage CT
82-year-old man. Image is example of reducing coverage to reduce dose. Other than first postoperative CT, post–stent graft CT examinations are done with reduced coverage from just above stent to pelvis, reducing dose by at least 50%.
Source: AJR 2013; 201:33–40

Dose reduction strategies for CT can vary by institution, but at their core, these strategies require radiologist and technologist buy-in as well as an understanding of the appropriate technology for a given department’s needs, according to an article published in the July issue of the American Journal of Roentgenology.

“Optimizing the ‘right’ minimum dose for a range of patient sizes is tough and requires attention to all the tools of dose prescription to reduce variability in image quality,” wrote Amy K. Hara, MD, of the Mayo Clinic Arizona in Scottsdale, and colleagues.

The authors underscored the criticality of engaging staff and emphasized strategies for creating a dose reduction team. This team should consist of a team leader—perhaps the medical director of CT—along with radiologists, technologists and, if possible, CT physicists. Physicists manage the protocols, radiologists identify exams to target for dose reduction and technologists provide input on workflow issues and keep logs of patients with reduced-dose exams, suggested Hara and colleagues.

Since one of the biggest barriers to implementing CT dose reduction is the attitudes of the radiologists—who may be resistant because of concerns about image quality or a may not believe in the risks of CT radiation—getting them to buy-in is a key step. The authors recommend making CT dose reduction an institutional, rather than departmental, priority to further momentum for change.

“Successfully introducing even the idea of CT dose reduction should be done not as a philosophical discussion of whether should we do it but rather as a clear statement that this is becoming increasingly required by the Joint Commission and U.S. Food and Drug Administration,” wrote Hara and colleagues.

After rallying the troops, the smallest and easiest changes suggested by the authors were reducing the number of scanning phases, reducing the scanning coverage or simply not performing scans where the benefit is questionable.

The next step is to optimize protocols, which can be done in a number of ways, including:

  • Leverage automated tube current modulation, which can be accomplished through automated tube current modulation to adjust current based on attenuation of the body region.
  • In addition to automated current modulation, adjusting dose according to patient body size can further optimize protocols.
  • Adjust tube current and peak kilovoltage changes between different vendor's scanners, which can vary based on manufacturer.

“When making protocol changes, we found it best to start on a single, usually least busy, outpatient scanner, if possible,” wrote Hara and colleagues. “In this era of high efficiency, the technologists are under stress to get patients on and off the scanner as quickly as possible with minimal errors. In general, implementing a change on a non–emergency department outpatient scanner can help technologists learn in the least stressful environment.”

The largest change to make in CT dose reduction efforts is the use of denoising and iterative reconstruction techniques, according to the authors. These come in two flavors: vendor-specific and vendor-neutral. Hara and colleagues wrote that vendor-specific techniques are typically easy to implement, but are generally more expensive and there’s the obvious limitation that they can be used only in scanners from the same vendor. Vendor-neutral denoising and reconstruction techniques offer more flexibility at a reduced cost, but require more upfront work to implement.

Looking ahead, Hara and colleagues wrote that with further technological improvements in model-based iterative reconstruction and automated kilovoltage selection, submillisievert abdominal-pelvic exams could be achieved.