# US 2013/0156152 A1 · Method and system for maintaining iso center constant in an iso centric x-ray imaging system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0156152 A1 - Document ID: US20130156152A1 - Status: Published application - Kind: A1 - Application number: 13/332,287 - Filed: 2011-12-20 - Published: 2013-06-20 - Earliest claimed: 2011-12-20 - Assignees: General Electric Company - Inventors: Hiteshkumar T. Boda; Gurudatt S. Kamat - Web page: https://patentgrep.com/patent/US20130156152A1 ## CPC - A61B 6/03: Computed tomography [CT] - A61B 6/04: Positioning of patients; Tiltable beds or the like - A61B 6/0487: {Motor-assisted positioning} - A61B 6/0492: {using markers or indicia for aiding patient positioning} - A61B 6/08: Auxiliary means for directing the radiation beam to a particular spot, e.g. using light beams - A61B 6/4441: {the rigid structure being a C-arm or U-arm} - A61B 6/4476: {related to motor-assisted motion of the source unit} - A61B 6/469: {for selecting a region of interest [ROI]} - A61B 6/481: {involving the use of contrast agents} - A61B 6/504: {for diagnosis of blood vessels, e.g. by angiography} - A61B 6/542: {involving control of exposure} - A61B 6/545: {involving automatic set-up of acquisition parameters} - A61B 6/547: {involving tracking of position of the device or parts of the device} - A61B 6/58: Testing, adjusting or calibrating thereof - A61N 5/1049: {for verifying the position of the patient with respect to the radiation beam} - A61N 5/1069: {Target adjustment, e.g. moving the patient support} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - 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 A method of maintaining a constant iso-center point, while dynamically changing an area of interest during an imaging procedure is provided. The method comprises: allowing a user to move from an initial area of interest to new area of interest by allowing permissible axes motions; dynamically calculating the iso-center point while moving from the initial area of interest to the new area of interest as a function of relative distance between the initial area of interest and the new area of interest and as a function of parameters indicating relative motion of permissible axes; identifying the new area of interest by using at least one permissible axis motion; and calculating the iso-center point at the new area of interest after locking all the permissible axes motions except table tilt axis movement. ## Claims ### Claim 1 A method of maintaining a constant iso-center point while dynamically changing an area of interest during an imaging procedure, the method comprising: allowing a user to move from an initial area of interest to new area of interest by allowing permissible axes motions; dynamically calculating the iso-center point while moving from the initial area of interest to the new area of interest as a function of relative distance between the initial area of interest and the new area of interest and as a function of parameters indicating relative motion of permissible axes; identifying the new area of interest by using at least one permissible axis motion; and calculating the iso-center point at the new area of interest after locking all the permissible axes motions except table tilt axis movement. ### Claim 2 (depends on 1) The method as claimed in claim 1, wherein identifying the new area of interest comprises defining the new area of interest as a function of distance between the initial area of interest and the new area of interest. ### Claim 3 (depends on 1) The method as claimed in claim 1, wherein identifying the new area of interest comprises moving the patient table and gantry in at least one of the permissible axes motion until the defined area of interest is identified. ### Claim 4 (depends on 1) The method as claimed in claim 1, wherein calculating the iso-center point at the new area of interest comprises using patient table position and gantry position at the new area of interest and the relative distance between the initial area of interest and the new area of interest. ### Claim 5 A method of maintaining a constant iso-center point and a constant X-ray exposure in an x-ray imaging system while moving from one area of interest to another area of interest, the imaging system comprising a movable patient table and a rotatable gantry, the method comprising: calculating an iso-center point with reference to an initial area of interest; unlocking at least one axis motion from the defined iso-center point corresponding to the initial area of interest; manually altering at least one axis motion along with a patient table tilt movement to locate a new area of interest; dynamically tracking the iso-center point at a given instance using the constant axis motion parameters along with relative motion of variable axes; stopping other axis motion except patient table tilt movement upon identifying the new area of interest; and calculating the iso-center point with reference to the new area of interest using all the axes motion parameters. ### Claim 6 (depends on 5) The method as claimed in claim 5, wherein calculating an iso-center point with reference to an initial area of interest comprises locking all axes motions except patient table tilt motion. ### Claim 7 (depends on 5) The method as claimed in claim 5, wherein calculating an iso-center point with reference to an initial area of interest comprises calculating the iso-center point using patient table axes parameters including a current longitudinal position and a current lift position of the patient table and the table tilt angle and gantry axes parameters including gantry tilt angle, pivot and C-arc position of the gantry. ### Claim 8 (depends on 5) The method as claimed in claim 5, wherein dynamically tracking the iso-center point at a given instance comprises tracking the iso-center point while moving the area of interest from the initial area of interest to the new area of interest as a function of the relative distance between the initial area of interest and the new area of interest. ### Claim 9 (depends on 5) The method as claimed in claim 5, wherein dynamically tracking the iso-center point comprises calculating the iso-center point as function of all unlocked axes motion and distance from the area of interest. ### Claim 10 (depends on 5) The method as claimed in claim 5, wherein calculating the iso-center point with reference to the new area of interest comprises calculating the iso-center point as a function of patient table axes parameters and gantry axes parameters at the new area of interest along with the distance between the initial area of interest and the new area of interest. ### Claim 11 An iso-center based imaging system comprising: a movable patient table; a rotatable gantry; and a processor configured to control the movements of the gantry and the patient table, the processor comprising: a tracking module configured to dynamically calculate the iso-center point while moving from one area of interest to another, using the relative motion of all unlocked axes; and a fixing module configured to compute the iso-center point corresponding to the identified area of interest using all the axes information. ### Claim 12 (depends on 11) The system as claimed in claim 11, wherein the tracking module is configured to calculate the iso-center point as a function of all unlocked axes motion and distance from the identified area of interest. ### Claim 13 (depends on 11) The system as claimed in claim 11, wherein the fixing module is configured to calculate the iso-center point after locking all the axes motion except table tilt movement. ### Claim 14 (depends on 11) The system as claimed in claim 11, wherein the fixing module is configured to calculate the iso-center point initially using patient table axes parameters including a current longitudinal position and a current lift position of the patient table position and the table tilt angle and gantry axes parameters including gantry tilt angle, pivot and C-arc position of the gantry. ### Claim 15 (depends on 11) The system as claimed in claim 11, wherein the fixing module is configured to calculate the iso-center point with reference to the new area of interest as a function of patient table axes parameters and gantry axes parameters at the new area of interest along with the distance between the initial area of interest and the new area of interest.