Clinical

CT-guided interventions can be performed with less radiation

Last Updated: 2006-05-08 13:54:10 -0400 (Reuters Health)

By Karla Gale

NEW YORK (Reuters Health) - CT radiation doses can be reduced by up to 80% and still provide enough information for percutaneous biopsies to be performed and catheters to be placed, according to a presentation at the American Roentgen Ray Society annual meeting.

Typically, doses required for accurate diagnosis range from 175 to 250 milli-ampere-seconds (mAs), presenter Dr. Brian Lucey told Reuters Health.

But for percutaneous interventions, "all we're doing is confirming that the needle or catheter is placed within the mass or the area to be drained, which typically range from 4 to 10 cm in diameter," he noted, "which does not require the same high-quality image as used for diagnosis."

To evaluate the feasibility of performing CT-guided interventional procedures using very low mAs, Dr. Lucey and his associates at Boston University Medical Center documented success rates for 201 percutaneous biopsies and 90 percutaneous catheter placements over an 18-month period using 30 mAs.

Only three patients required a dosage higher than 30 mAs to place a catheter successfully, and even then, lower doses were used (65 mAs for two patients and 200 mAs for one) than were required for diagnosis.

The success rate for biopsies was 93.5%, which was actually higher than the 87.5% success rate during the 12 months prior to the introduction of the low-dose radiation technique. Even when a second scan at a higher dose was required, exposure still was less than it would have been with the standard procedure.

Dr. Lucey noted that the interventional techniques were used primarily for "lung, liver, spleen, kidney, pancreas, adrenal lymph nodes, omentum, soft tissue and bone. It's easiest for imaging chest and bone masses and harder for those in the liver, but essentially we can use the low-dose imaging for everything."

He explained that their reason for decreasing radiation exposure is to lower the risk of developing cancer later in life.

"That's especially important for patients facing repeated CT scans," he added. "For example, many patients with Crohn's disease often get a lot of CT exams and a lot of abscesses that require CT imaging for drainage."