Patent ID: 6345114
Filing Date: 2002-02-05
Classification: A61B,A61N

Abstract:
A method of calibrating a radiotherapy machine comprising the steps of:(a) irradiating a volume of known composition and geometry with a beam of radiation having a beam intensity profile; (b) acquiring a measured portal image of the dose of the beam of radiation after it has passed through the volume along a number of rays; (c) employing an electronic computer receiving the measured portal image and the character and geometry of the volume and operating a stored program to: (i) model an expected portal image based on an irradiation of the volume with an assumed beam intensity profile; (ii) compare the expected portal image with the measured portal image to produce a correction image; (iii) incrementally modifying the assumed intensity profile based on the correction image; (iv) repeating steps (i)-(iii) with the assumed intensity profile being the modified assumed intensity profile; (d) outputting the modified assumed intensity profile as a measure of the intensity profile; and (e) calibrating the radiotherapy machine based on the modified assumed intensity profile.