Improving CT Scans, Treating MS: Notes from an IR Conference

I am slightly obsessed with the topic of radiation exposure, since I have covered radiation overdoses from CT scans on this blog and written about radiation issues in post-earthquake Japan and treating radiation injuries for Medscape. So I was interested to learn about efforts to decrease radiation exposure in patients when I stopped by the Society of Interventional Radiology's annual meeting in San Francisco last week.

Interventional radiologists (IRs) perform many minimally-invasive procedures, such as placing stents in arteries to increase blood flow or delivering targeted chemotherapy to a tumor. These procedures can often replace more invasive and riskier open surgeries. But the flip side of this medical progress is that some of the imaging technologies used to guide these procedures, specifically CT scans and X-rays, expose patients to ionizing radiation, the type of radiation that can harm DNA. 

A poster at the session explained that CT scans are a key source of radiation exposure in the U.S. This exposure can be decreased by adjusting the CT scanner and basing the dose on the patient's BMI, explained author J. Collins et al. ("A Practical Guide to CT Dosimetry for the Interventional Radiologist").

Another intriguing development covered at the conference: the use of angioplasty (widening a narrowed blood vessel) to treat multiple sclerosis. Angioplasty can clear blockages in veins that might contribute to MS symptoms. Some patients who were studied reported that their symptoms improved after the procedure. The course of MS can be so fickle, though, that it's hard to tell whether symptoms improved or the disease simply relapsed for a while, reporter Laird Harrison explained in a WebMD article on the topic ("Treating Clogged Veins Improves MS, Study Says"). The press release about the procedure from the Society of Interventional Radiology is available online.

Adults and Kids Harmed by CT Scans

Radiation overdoses in both adults and children from computed tomography (CT) scans have lead to a lot of worry and finger-pointing in the news recently.

The issue was uncovered in a New York Times investigation by Walt Bogdanich of patients who experienced strange side effects after receiving CT scans to measure blood flow to their brain. CT scanners take a series of X-rays to create three-dimensional images of the body.

Bogdanich reported that over 400 patients at hospitals in California, Alabama, and Florida received as much as 13 times the recommended radiation doses from CT scanners. After the scans, the patients developed symptoms such as hair loss, confusion, and memory loss, and might now be at increased risk of developing cancer and brain damage.

Most of the scanners in question were made by GE Healthcare, Bogdanich reported. Hospital staff blame the overdoses on faulty training about how to use a new feature of the CT scanners designed to reduce the radiation dose. They say that a glitch in the scanners' software unintentionally lead to radiation overdoses. GE Healthcare, on the other hand, blames the hospital staff for misusing and misunderstanding this feature, and for not tracking the radiation doses more carefully for each patient.

The FDA had been investigating this issue over the past year, but "was unaware of the magnitude of those overdoses until The Times brought them to the agency's attention," Bogdanich wrote.

Meanwhile, Chicago Tribune reporter Judith Graham wrote that many children are receiving unnecessary adult-sized doses of radiation when they get CT scans. Because children often receive CT scans at hospitals for adults, the radiation doses are not always adjusted for the child's weight and size.