Jeffrey F. Williamson

A group of researchers led by Jeffrey F. Williamson, Ph.D., professor of radiology at Washington University School of Medicine in St. Louis, has developed a new approach for using three-dimensional CT imaging to more accurately assess the amount of radiation being received by normal organs during brachytherapy, which implants radioactive seeds into a tumor.The new approach should allow radiologists to avoid co-lateral damage.Williamson will present this advance recently at the annual meeting of the American Society for Therapeutic Radiology and Oncology in Boston.

Brachytherapy for cervical cancer introduces radioactive seeds into the vagina and uterus by means of a metal applicator.In combination with daily external radiation therapy treatments, at least two different brachytherapy implants need to be be performed several times over a period of 6-7 weeks.CT imaging, which clearly shows the normal pelvic organs at risk, is typically not used to ensure that normal tissues are spared.This is because CT images taken after each brachytherapy insertion or group of external treatments can't be aligned with each other due to deformation and displacement of the pelvic tissues because of tumor shrinkage, inserting and removing the applicator and swelling of normal tissues in response to therapy alter the positions of pelvic organs.Thus the total dose to each visualized piece (called "voxel") of tissue from all procedures can't be determined.