The feasibility of imaging soft tissues with neutrons (neutron radiography) from a medical linac as a complement to the conventional X-ray portal imaging is proven. Both direct and indirect neutron radiographs have been successfully obtained. In the direct method, a film is exposed to the beam through a neutron converter. The latter transforms the neutrons into /spl gamma/-rays which subsequently darken the film. In the indirect method, a metallic foil is exposed to the neutrons in the beam and subsequently becomes activated. The resulting gamma rays from the decay of the activation reaction are subsequently used to darken a film and produce an image. In addition, because most of the neutrons generated are fast (average 1 to 2 MeV), a fast neutron radiograph has also been successfully obtained using a CR-39 plate. An exit dosimetry method is suggested for boron neutron capture therapy (BNCT) using neutron radiography. In this manner, the concentration distribution of boron-10 and/or the neutron capture dose in the irradiated region can be obtained through proper calibration. Possible clinical applications of neutron radiography with medical linacs are discussed.
N. Adani, B. Fallone
Proceedings of the 22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (Cat. No.00CH37143)