New CT Method Could Lower Radiation Exposure

July 23, 2020

Technique splits X-ray beam into thin streams that deliver the same image quality with reduced dose.

Patient radiation exposure continues to be a concern throughout radiology. But, new research from the University College of London (UCL) could result in reduced dose with CT scans.

In a study published in Physical Review Applied, investigators tested a technique that splits a full X-ray beam into thin beamlets. The resulting image produced the same quality at a much lower dose, said the team led by Charlotte Hagen, Ph.D., from the UCL department of medical physics and biomedical engineering.

The team demonstrated the technique on a small sample in a micro CT scanner and said that adapting it to medical scanners is the plan.

“Being able to reduce the dose of a CT scan is a long-sought goal,” Hagen said. “Our technique opens new possibilities for medical research, and we believe that it can be adjusted for use in medical scanners, helping to reduce a key source of radiation for people in many countries.”

To test this method, Hagen’s team placed a mask with tiny slits over the X-ray beam to break up the ray into thin beamlets. They, then, moved the sample to be imaged in a cycloidal motion to make sure the entire object received quick irradiation. In comparison to the conventional CT method that rotates a sample while a full beam shines on it, the new method produced the same image quality at a significantly lower radiation dose, they said.

According to Hagen, in addition to rotating an X-ray beam around a patient – as is done with conventional CT – this new cycloidal method adds in simultaneous backwards and forwards motion. And, the beamlets produce the sharper image, she said, because the X-ray is able to determine where information is emanating from more precisely.

In doing so, said Hagen’s colleague Sandro Olivo, Ph.D., UCL professor in applied physics, the new method addresses two problems – dose exposure and image resolution.

“It can be used to reduce the dose, but if deployed at the same dose it can increase the resolution of the image," he said. "This means that the sharpness of the image can be easily adjusted using masks with different-sized apertures, allowing greater flexibility and freeing the resolution from the constraints of the scanner’s hardware.”

The details of their study can be found here.