US 12,233,285 B2
Systems, methods, and devices for radiation beam asymmetry measurements using electronic portal imaging devices
Reto Ansorge, Zurich (CH); Mathias Lehmann, Zurich (CH); and Stefan J. Thieme-Marti, Windisch (CH)
Assigned to VARIAN MEDICAL SYSTEMS, INC., Palo Alto, CA (US)
Filed by Siemens Healthineers International AG, Steinhausen (CH)
Filed on May 16, 2023, as Appl. No. 18/197,978.
Application 18/197,978 is a continuation of application No. 17/523,544, filed on Nov. 10, 2021, granted, now 11,691,031.
Application 17/523,544 is a continuation of application No. 16/846,935, filed on Apr. 13, 2020, granted, now 11,207,546, issued on Dec. 28, 2021.
Application 16/846,935 is a continuation of application No. 15/449,586, filed on Mar. 3, 2017, granted, now 10,682,528, issued on Jun. 16, 2020.
Prior Publication US 2024/0017095 A1, Jan. 18, 2024
Int. Cl. A61N 5/10 (2006.01); G01T 1/29 (2006.01)
CPC A61N 5/1075 (2013.01) [G01T 1/2914 (2013.01); A61N 5/1045 (2013.01); A61N 2005/1076 (2013.01); A61N 5/1081 (2013.01); A61N 2005/1089 (2013.01); A61N 2005/1091 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A method for determining a radiation beam tilt relative to a collimator axis of rotation of a radiation treatment device, comprising:
emitting a radiation beam from a source positioned at the collimator axis of rotation, the radiation beam passing through an aperture of the collimator positioned around the collimator axis at a first position so as to be received by an electronic portal imaging device positioned at a distance from the source along the collimator axis of rotation;
measuring intensity of the radiation beam received by the electronic portal imaging device;
rotating the collimator around the collimator axis by 180 degrees to a second position and measuring the intensity of the radiation beam that passes through the aperture by the electronic portal imaging device,
comparing the intensity of the radiation beam measured at the first location of the collimator and the intensity of the radiation beam measured at the second location of the collimator,
calculating an asymmetry value from the difference in the measured intensities; and
calculating radiation beam tilt from the asymmetry value.