Functional anatomic imaging in radiation therapy planning

Improvements in techniques for the delivery of curative radiation have paralleled the advances in three-dimensional imaging devices, specifically, computed tomography and magnetic resonance imaging. These modalities supply the high-resolution image data which, when transferred to radiotherapy computers, allows the construction of a "virtual patient" and calculation of radiation dose that can be delivered within a three-dimensional volume. Although anatomic methods have long been the main stay of cancer imaging, it now clear that functional imaging, provided by positron emission tomography and other nuclear medicine techniques, provides additional critical information regarding tumor biologic activity. The additional step of fusion of functional and anatomic images further refines radiation treatment planning.