Combining PET and CT scans leads to more accurate radiation therapy for lung cancer patients

Using Positron Emission Tomography in addition to Computed Tomography can reduce the amount of radiation exposure to normal tissue in some lung cancer patients, according to a new study published in the March 1, 2005, issue of the International Journal of Radiation Oncology-Biology-Physics, the official journal of ASTRO, the American Society for Therapeutic Radiology and Oncology.

The study, conducted on 21 patients with non-small cell lung cancer, created two three-dimensional conformal radiation treatment plans, one with CT-based planning and the second with a combination of PET and CT-based planning. The researchers found that, in general, the size of the radiation fields could be decreased by using PET scan information, which meant less radiation exposure of the healthy lung tissue and the esophagus.

“This study underlines the great potential benefit of incorporating PET scan data into radiotherapy planning, both to decrease side-effects and increase cure rates,” said Dirk de Ruysscher, M.D., Ph.D., a radiation oncologist at University Hospital Maastricht in The Netherlands and co-author of the study. “Because of the smaller radiation fields, the radiation dose may theoretically be increased without increasing the side-effects compared to CT-based planning alone. This may lead to a higher chance of achieving tumor control.”

The study showed that the two non-invasive imaging methods were combined because PET scans were shown to have a higher accuracy than CT scans to predict which lymph nodes contain cancer cells and which do not. PET scans alone do not give enough anatomical information to accurately define the tumor volume.