A practical method for estimating high-energy X-ray spectra using the iterative perturbation principle proposed by Waggener

We have remodeled the X-ray spectra estimation method, originally proposed by Waggener et al. (Med. Phys. 26(1999)1269), based on the iterative perturbation technique to minimize differences between measured and calculated transmission curves using low Z attenuators. With our approach, the iterative perturbation cycle is repeated until a reasonable spectrum is obtained. Furthermore, the degree of differences between the measured and calculated transmission curves is also checked using high Z attenuators. The present experimental study, conducted using 4, 10 and 15 MV X-ray beams from a linear accelerator, demonstrated that the spectrum varies strongly with the off-axis distance. (C) 2003 Elsevier Science Ltd. All rights reserved.