Gently Imaging to Reduce Radiation Exposure

February 15, 2017

A medical imaging technologist comforts a child who is about to undergo a scan.

"Is it absolutely necessary for my daughter to have a CT scan? I'm worried about her exposure to radiation."

Virtually every week, Lurie Children's medical physicist Christina Sammet, PhD, answers a similar question from a concerned parent whose child needs to undergo an x-ray or CT scan to diagnose a disease or injury.

"Recently I spoke with the mother of a patient who had multiple fractures and needed x-rays," says Christina. "She was worried that her child was going to get cancer from this one medically-indicated exam. I explained to her that the radiation exposure from our x-ray scanners is about the same as the amount of naturally occurring radiation we're exposed to every day."

Imaging gently

James Donaldson, MD, is Head of Lurie Children's Department of Medical Imaging, whose services span the breadth of the hospital's medical specialties. He says that because children are more sensitive to radiation than adults unless a CT scan or x-ray is absolutely necessary, non-radiation imaging methods such as ultrasound and MRI scans are used instead. In fact, Dr. Donaldson, the Earl J. Frederick Distinguished Professor in Radiology, says the number of CT scans performed at Lurie Children's has been reduced by 50 percent over the last five years.

"When we do perform CT scans or x-rays, we scan the smallest area possible," he says. "Also, we use single-phase scanning, so we don't scan the same area over and over again. And we use the lowest power possible to get the diagnostic-quality image we need."

Lurie Children's has played a leadership role in the national "Image Gently" campaign. The education and awareness initiative to reduce exposure to diagnostic radiation was launched in 2007 by the Alliance for Radiation Safety in Pediatric Imaging.

Unique patients, unique scans

Lurie Children's team of three full-time medical physicists ensures patients receive as small a dose of radiation as possible. While virtually all children's hospitals have lowered the amount of radiation they use in imaging, children who are scanned at some adult and community medical centers may receive a larger-than-necessary radiation dose because many hospitals lack a staff medical physicist. That's why Dr. Sammet performs an important community service by providing technical and educational services at two of Lurie Children's partner hospitals—Northwestern Medicine Central DuPage Hospital and Northwestern Medicine Delnor Hospital.

The facts about radiation risk

Dr. Donaldson says that in recent years, media stories have resulted in concern from some parents about the possibility their child may develop cancer due to exposure to diagnostic radiation. Others confuse the low doses of radiation used in medical scans with the high-dose therapeutic radiation used to treat cancers.

Doses of radiation for medical imaging scans are measured in units called millisieverts (mSv). Recently, the American Association of Physicists in Medicine found that there is no evidence of elevated risk of cancer or other secondary effects from exposure to less than 50 mSv of radiation from a single procedure or 100 mSv for multiple procedures.

"Whenever possible, we will choose a type of imaging that doesn't use any radiation,” says Dr. Donaldson. "However, there are situations when there is no appropriate alternative form of imaging, and radiation may be required. Sometimes imaging studies can be critical and even life-saving. But, when radiation is used, it must be managed carefully and wisely."

This article originally appeared in the Winter 2017 issue of Heroes magazine.