Method for increasing the accuracy of a radiation therapy apparatus
AssigneeVarian Associates, Inc.
InventorsEdward J. Seppi, Edward G. Shapiro, John M. Pavkovich
Life of this patent
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Abstract
Disclosed is a method for increasing the accuracy of images obtained in radiation therapy apparatus, such as a computed tomography simulator which employs an image intensifier and a photodiode detector for converting light from the image intensifier to electrical signals for further processing. The method recognizes that a significant amount of crosstalk can exist in the image intensifier and photodiode detector chain and provides a series of steps for adjusting the electrical signals obtained from the photodiode detector to compensate for the crosstalk.
Claims2
A method for increasing the accuracy of a radiation therapy simulator machine, wherein the radiation therapy simulator machine has a source of X-ray photons;
- and X-ray image intensifier tube, said intensifier tube providing a visible light output in response to X-ray photons impinging on an input of said intensifier tube;
- and array of photodiodes which provide an output proportional to a visible light input;
- and an optical means for coupling the visible output of said intensifier tube to the array of photodiodes;
- the method comprising the step of eliminating crosstalk in the image intensifier tube and the optical means, wherein the crosstalk eliminating step includes the steps of:
- a. applying the X-ray photons to the intensifier tube input so that one of the array of photodiodes is fully illuminated by a visible light output from the intensifier tube;
- b. measuring the response of all of the array of the photodiodes;
- c. repeating steps a. and b. until each of the array of photodiodes has been fully illuminated by a visible light output from the intensifier tube;
- d. zeroing out the responses of the fully illuminated photodiodes;
- and
- e. using the remaining measurements as an error term to deconvolve subsequent measurements made by the radiation therapy simulator machine.
Dependencies are inferred from the claim text.