Abstract: The detector of the present invention is suitable for use in a radiation therapy simulator machine. The detector comprises an X-ray image intensifier tube to convert X-rays into photons, a linear array of photodiodes to convert the photons to electrical signals, optical means for coupling the photons to the linear array of photodiodes, and electronic signal processing means for conditioning the signals from the photodiodes. The conditioning includes the use of low noise, phaselocked sampling electronics, implementation of a dual sampling technique for increasing dynamic range, implementation of a linearizing technique for increasing the accuracy of the measurements, and implementation of techniques for adjusting the measurements for point spread and background noise effects.

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.