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Combining PET and CT scans makes cancer treatment more accurate

May 02, 2006

Doctors have discovered that combining images derived from positron emission tomography and computed tomography in the planning and delivery of radiation treatment for patients with head and neck cancer leads to more accurate delivery of the radiation dose and an increased chance for survival. The study was published in the May 2006 issue of the International Journal of Radiation OncologyBiologyPhysics, the official journal of ASTRO, the American Society for Therapeutic Radiology and Oncology.

The pilot study, conducted on 28 patients, set out to discern whether combining PET and CT images to plan intensity modulated radiation therapy, or IMRT, treatments for patients resulted in better delivery of the radiation and lower recurrence rates. The doctors fused images captured from both the PET and CT scans and found that the proposed treatment plans were very different in 14 of 16 patients whose plans had been designed using CT scanning alone. Out of the 28 patients who were followed for more than six months after treatment, 16 showed no signs of recurrence. The current standard of care for head and neck cancer patients involves surgery or radiation for early-stage cancer and some combination of radiation, surgery or chemotherapy for advanced cases. The high doses of radiation therapy that patients receive cause toxicity which can negatively impact a patients' quality of life. This study shows that IMRT, which modifies the intensity of the radiation beams to both the tumor and surrounding healthy tissue in order to avoid side effects while killing the cancer, can be used as an alternative to standard radiation therapy and could improve the patients' quality of life after cancer treatment.

"Even though it's a small sample group, this study shows the fusion of PET/CT can significantly improve treatment planning for radiation therapy and might ultimately help patients with head and neck cancer who receive radiation therapy beat their disease," said Dian Wang, M.D., Ph.D., lead author of the study and a radiation oncologist at the Medical College of Wisconsin in Milwaukee. "In addition, these patients may experience fewer side effects as the PET/CT-based target definition decreases the likelihood of including adjacent tissues that do not contain microscopic tumor cells in the high dose treatment volume. We're hoping that this study will encourage our colleagues to consider PET/CT fusion with IMRT for both initial staging and treatment planning for head and neck cancer patients."

American Society for Therapeutic Radiology and Oncology