Alignment of the coordinate systems of external beam radiotherapy and magnetic resonance imaging systems

Abstract

The invention provides for a medical instrument () comprising a magnetic resonance imaging system () operable for acquiring magnetic resonance data () from a subject () within an imaging zone () and an external beam radiotherapy system () operable for irradiating a target zone () within the imaging zone. The medical instrument further has a radiation beam generation system (″) operable for generating a radiation beam (″) and a radiation beam detection system (') operable for acquiring radiation beam detection data () descriptive of the radiation beam. Instructions cause a processor () controlling the instrument to receive () planning data () descriptive of a spatially dependent radiation dose and generate () external beam radiotherapy control commands () using the radiation dose. The instructions causes the processor to repeatedly: control () the external beam radiotherapy system to irradiate the target zone using the external beam radiotherapy system control commands; generate () the radiation beams using the radiation beam generation system; measure () the radiation beam detection data using the radiation beam detection system; acquire () the magnetic resonance imaging data using the magnetic resonance imaging system, generate () a magnetic resonance image () using the magnetic resonance image data, determine () a registration () of the magnetic resonance image to the radiation beam detection data; calculate () a mapping () using the registration; and modify the external beam radiotherapy system control commands using the mapping.