SIR: Low-dose protocol reins in rad dose during lung biopsy
New guidelines for CT-guided biopsies of lung nodules can significantly reduce radiation exposure, according to research presented March 25 at the Society of Interventional Radiology's (SIR) 37th annual scientific meeting in San Francisco.
"Statistically, many people who undergo screening [CT] will have nodules detected with CT and a biopsy may be recommended. We want to minimize the side effects of the biopsy procedure," said Jeremy Collins, MD, assistant professor of radiology at Northwestern University in Chicago.
Collins and colleagues examined a new set of CT imaging parameters to reduce radiation exposure while maintaining image quality. The new protocol downshifts the amount of energy the CT scanner uses to produce images and moderates the current of the x-ray tube to emit a lower dose during the examination.
In August 2010, Northwestern implemented a guidance protocol involving a 120 kVp spiral acquisition with a pitch of 0.8 and 80 mAs for planning, followed by sequential 100 kVp and 80 mAs acquisitions for guidance, the researchers explained in the study abstract.
The researchers reviewed data from 100 people, half of whom underwent CT-guided biopsies prior to the new protocol and half after the protocol went into effect.
The low dose protocol led to a dramatic 66 percent drop in radiation dose from 747.9 mGy*cm to 251.8 mGy*cm. Image quality was maintained for all of the CT-guided biopsies; there was no significant difference in the number of CT acquisitions needed for guidance between groups. Although the protocol was voluntary, the researchers reported 100 percent adherence to the use of sequential scanning for needle guidance.
"The modification to the scanner technique is simple and can be applied to any existing CT scanner system," Collins said.
"The new protocol can be adopted immediately to reduce exposure, but interventional radiologists will still need to evaluate each person on a case-by-case basis, especially smaller people or those who have anatomy that is more difficult to image. The dose can be reduced even further for children, but more studies need to be done to tailor the protocol," he concluded.
"Statistically, many people who undergo screening [CT] will have nodules detected with CT and a biopsy may be recommended. We want to minimize the side effects of the biopsy procedure," said Jeremy Collins, MD, assistant professor of radiology at Northwestern University in Chicago.
Collins and colleagues examined a new set of CT imaging parameters to reduce radiation exposure while maintaining image quality. The new protocol downshifts the amount of energy the CT scanner uses to produce images and moderates the current of the x-ray tube to emit a lower dose during the examination.
In August 2010, Northwestern implemented a guidance protocol involving a 120 kVp spiral acquisition with a pitch of 0.8 and 80 mAs for planning, followed by sequential 100 kVp and 80 mAs acquisitions for guidance, the researchers explained in the study abstract.
The researchers reviewed data from 100 people, half of whom underwent CT-guided biopsies prior to the new protocol and half after the protocol went into effect.
The low dose protocol led to a dramatic 66 percent drop in radiation dose from 747.9 mGy*cm to 251.8 mGy*cm. Image quality was maintained for all of the CT-guided biopsies; there was no significant difference in the number of CT acquisitions needed for guidance between groups. Although the protocol was voluntary, the researchers reported 100 percent adherence to the use of sequential scanning for needle guidance.
"The modification to the scanner technique is simple and can be applied to any existing CT scanner system," Collins said.
"The new protocol can be adopted immediately to reduce exposure, but interventional radiologists will still need to evaluate each person on a case-by-case basis, especially smaller people or those who have anatomy that is more difficult to image. The dose can be reduced even further for children, but more studies need to be done to tailor the protocol," he concluded.