Changing protocols could help reduce radiation exposure in certain CT-guided biopsies

Twitter icon
Facebook icon
LinkedIn icon
e-mail icon
Google icon
 - Lung Cancer Biopsy
Biopsy targets have shrunk dramatically since the early days of CT, when a 6-cm lung nodule (left) was more likely to be targeted for biopsy. In advanced practice today, for example, a 5-mm partly solid nodule (right) with a 2-mm solid component was biopsied to reveal an adenocarcinoma.
Source: David F. Yankelevitz, MD

With the help of radiologists following new procedures, a new study shows that institutions were able to decrease the amount of radiology patients were exposed to during CT-guided lung biopsies by more than 64 percent over 18 months.

The authors of the study, published in Academic Radiology, set out to see if they could reduce patients’ exposure to possibly damaging radiation in imaging. They theorized a lung biopsy could be the best option for such a test, because the decline in picture quality due to the decline in radiation probably wouldn’t affect quality of care.

To test that theory, they measured radiation exposure through 175 CT-guided lung biopsies using old protocols for about a year and a half, starting in September 2009. Then they measured patients’ radiation exposure in 238 scans from February 2011 to August 2012, after the radiologists developed a new protocol—a three-phase incremental decrease in the recommended kilovoltage peak, milliamperes and scan coverage in every CT.

The researchers found the overall exposure to people receiving CT-guided lung biopsies decreased over each of the three phases by about 75 percent, 52 percent and 66 percent, respectively. That translates to a 64 percent mean reduction in overall radiation exposure in 18 months.

“Radiation dose was relatively stable in the 18 months before the protocol change, and immediately decreased in the 6-month period afterward," wrote Kimberly G. Kallianos, MD, et al. "This immediate decrease in radiation dose persisted throughout the subsequent two 6-month periods following the protocol change, thereby demonstrating 18 months total of reduced doses.”

The study authors calculated that the rate of diagnostic results achieved in both protocol groups was between 75 and 80 percent, meaning the lower image clarity in the lower-radiation group didn’t affect the accuracy of the tests. This could be because scans used to guide needles don’t need to be as clear as other kinds of scans.

The study pointed out that radiation levels were reduced institution-wide, even though the protocol changes were implemented at the individual physician level. The study authors said this suggests that other institutions could implement similar CT-guided lung biopsy protocol changes and see similar reductions in radiation exposure, therefore reducing patients’ risks associated with contact with radiation.