Lung imaging method helps lower radiotherapy toxicity, study finds

Radiotherapy, a process designed to cure cancer by destroying cancerous tumors, can be harmful to patients if it targets the wrong areas. It is also can be difficult to manage. But new research found a method to perform selective radiotherapy, which can reduce toxicity in the body.

A study, published in Medical Physics by the American Association of Physicists in Medicine, found that radiotherapy that selectively avoids irradiating highly functional lung regions can reduce pulmonary toxicity, a type of lung damage usually in the form of inflammation that is severe in lung cancer patients.

Areas to be avoided during radiotherapy can be determined by looking at the perfusion, or blood flow, in the lungs.

Single-energy computed tomography (CT) pulmonary perfusion imaging is a form of radiotherapy that has higher spatial resolution, is quicker, more cost effective and can reduce pulmonary toxicity in the lungs since it focuses on one specific area.

The method was tested by Tokihiro Yamamoto, the lead author on the study and a radiation oncologist at the University of California Davis, and his team. They tested 14 canines, half of whom had healthy lungs and the other half who had diseased lungs.

The researchers studied CT scans of the dogs and found that spatial heterogeneity of regional perfusion was found to be higher for canines with diseased lungs than for canines with normal lungs. The average gravitationally directed gradient was strong for dogs with normal lungs, while it was moderate and nonsignificant for dogs with diseased lungs.

“This canine study demonstrated the accuracy of deformable image registration with subvoxel target registration errors on average, higher spatial heterogeneity of regional perfusion for diseased lung subjects than normal lung subjects, and a strong ventral-to-dorsal gradient for normal lung subjects, providing proof-of-principle for single-energy CT pulmonary perfusion imaging,” the authors wrote in the study.

Additionally, the imaging method could also be used to determine the extent of pulmonary toxicity after the completion of radiation treatments.

The next step is investigating the method on humans and comparing studies based on single-energy CT and alternative pulmonary perfusion imaging modalities.