# US 8,542,797 B2 · Radiotherapy apparatus configured to track a motion of a target region using a combination of a multileaf collimator and a patient support > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,797 B2 - Document ID: US8542797B2 - Status: Granted - Kind: B2 - Application number: 12/889,898 - Filed: 2010-09-24 - Published: 2012-03-29 - Granted: 2013-09-24 - Earliest claimed: 2010-09-24 - Assignees: Elekta AB (publ) - Applicants: David Anthony Roberts - Inventors: David Anthony Roberts - Web page: https://patentgrep.com/patent/US8542797B2 ## CPC - A61N 5/1049: {for verifying the position of the patient with respect to the radiation beam} - A61N 5/1045: {using a multi-leaf collimator, e.g. for intensity modulated radiation therapy or IMRT} - A61N 5/1065: {Beam adjustment} - A61N 5/1069: {Target adjustment, e.g. moving the patient support} - A61N 2005/1061: {using an x-ray imaging system having a separate imaging source} - A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B) ## Abstract The present invention provides a radiotherapy apparatus for applying therapeutic radiation to a target region of a patient, comprising a patient support, a source of radiation, a collimator comprising a plurality of leaves, a sensing system and control circuitry. The position of a target region is determined and resolved into two components orthogonal to the radiation beam axis. One component is assigned to the patient support, and the other to the collimator leaves, such that movement of the target region is compensated for and the radiation beam intersects is correctly targeted. ## Claims ### Claim 1 A radiotherapy apparatus for applying therapeutic radiation to a target region of a patient, the apparatus comprising: a patient support, on which the patient is positioned for treatment; a source of radiation, arranged to emit a beam of radiation along an axis towards the patient; a collimator comprising a plurality of leaves, moveable into the radiation beam in order to delimit an extent of the radiation beam; a sensing system, configured to determine a position of a target region; and control circuitry, configured to resolve said position into a first component in a first direction orthogonal to the radiation beam axis and a second component in a second direction orthogonal to the radiation beam axis, and to control the patient support to move in the first direction according to the first component, and the plurality of collimator leaves to move in the second direction according to the second component, such that the radiation beam intersects the target region. ### Claim 2 (depends on 1) A radiotherapy apparatus as claimed in claim 1, wherein the first component is orthogonal to the second component. ### Claim 3 (depends on 1) A radiotherapy apparatus as claimed in claim 1, wherein the target region undergoes cyclical motion, and wherein the patient support and the plurality of collimator leaves move such that the radiation beam tracks said cyclical motion. ### Claim 4 (depends on 3) A radiotherapy apparatus as claimed in claim 3, wherein said cyclical motion comprises substantially elliptical motion in a plane orthogonal to the radiation beam axis, and wherein the first direction is parallel to a minor axis of the elliptical motion, and the second direction is parallel to a major axis of the elliptical motion. ### Claim 5 (depends on 1) A radiotherapy apparatus as claimed in claim 1, wherein said collimator is rotatable about an axis parallel to the radiation beam axis. ### Claim 6 (depends on 1) A radiotherapy apparatus as claimed in claim 1, wherein said sensing system comprises a CT imaging system. ### Claim 7 (depends on 1) A radiotherapy apparatus as claimed in claim 1, wherein said patient support comprises a hexapod for adjusting a position of the patient support. ### Claim 8 A method of treating a patient by radiotherapy, in which a radiotherapy apparatus comprises a patient support, on which the patient is positioned for treatment, a source of radiation, arranged to emit a beam of radiation along an axis towards the patient, and a collimator comprising a plurality of leaves, moveable into the radiation beam in order to delimit the extent of the radiation beam, the method comprising: determining a position of a target region in the patient; resolving said position into a first component in a first direction orthogonal to the radiation beam axis, and a second component in a second direction orthogonal to the radiation beam axis; and moving the patient support in the first direction according to the first component, and the plurality of collimator leaves in the second direction according to the second component, such that the radiation beam intersects the target region. ### Claim 9 (depends on 8) A method as claimed in claim 8, wherein the first component is orthogonal to the second component. ### Claim 10 (depends on 8) A method as claimed in claim 8, wherein the target region undergoes cyclical motion, and wherein the patient support and the plurality of collimator leaves move such that the radiation beam tracks said cyclical motion. ### Claim 11 (depends on 10) A method as claimed in claim 10, further comprising: determining an axis along which the largest range of motion of the target region occurs; and rotating the collimator about an axis parallel to the radiation beam axis, such that said second direction is aligned with said axis along which the largest range of motion of the target region occurs. ### Claim 12 (depends on 10) A method as claimed in claim 10, wherein said cyclical motion comprises substantially elliptical motion in a plane orthogonal to the radiation beam axis, and wherein the first direction is parallel to a minor axis of the elliptical motion, and the second direction is parallel to a major axis of the elliptical motion. ### Claim 13 (depends on 8) A method as claimed in claim 8, wherein said patient support comprises a hexapod for adjusting a position of the patient support.