TOMOTHERAPY - A NEW CONCEPT FOR THE DELIVERY OF DYNAMIC CONFORMAL RADIOTHERAPY

Tomotherapy, literally ''slice therapy,'' is a proposal for the delive ry of radiation therapy with intensity-modulated strips of radiation. The proposed method employs a linear accelerator, or another radiation -emitting device, which would be mounted on a ring gantry like a CT sc anner. The patient would move through the bore of the gantry simultane ously with gantry rotation. The intensity modulation would be performe d by temporally modulated multiple independent leaves that open and cl ose across the slit opening. At any given time, any leaf would be (1) closed, covering a portion of the slit, (2) open, allowing radiation t hrough, or (3) changing between these states. This method would result in the delivery of highly conformal radiation. Overall treatment time s should be comparable with contemporary treatment delivery times. The ring gantry would make it convenient to mount a narrow multisegmented megavoltage detector system for beam verification and a CT scanner on the treatment unit. Such a treatment unit could become a powerful too l for treatment planning, conformal treatment, and verification using tomographic images. The physical properties of this treatment delivery are evaluated and the fundamental design specifications are justified .