Investigation of the convolution method for polyenergetic spectra
Related Experiment Video
Updated: Nov 8, 2026

ARL Spectral Fitting as an Application to Augment Spectral Data via Franck-Condon Lineshape Analysis and Color Analysis
Published on: August 19, 2021
N Papanikolaou1, T R Mackie, C Meger-Wells
1Department of Medical Physics, University of Wisconsin, Madison 53706.
Abstract:
The distribution of absolute dose per unit fluence from polyenergetic photon beams impinging upon a water phantom was calculated using two convolution approaches that properly account for beam hardening effects. Dose deposition kernels calculated previously using the EGS4 Monte Carlo code are convolved with the primary terma to give the dose for monoenergetic photon beams of energies ranging from 100 kev to 50 MeV. A polyenergetic dose distribution is composed of separately calculated monoenergetic components, which are appropriately weighted with the fluence spectrum to yield the polyenergetic dose distribution. Alternatively, a single convolution for the polyenergetic beam is considered, where a composite polyenergetic kernel is convolved with the respective polyenergetic terma. The effects of the polyenergetic kernel variance due to beam hardening as well as the effect of tilting the kernels for a diverging beam geometry were also examined. The depth dose data produced using the two proposed methods were compared with measured data and Monte Carlo simulations and showed good agreement.
Related Concept Videos
UV–Vis Spectroscopy of Conjugated Systems
One of the factors influencing λmax is the extent of conjugation in the...
Convolution: Math, Graphics, and Discrete Signals
To simplify the convolution integral, it is assumed that both the input signal and impulse response are zero for negative time values. The graphical convolution process...
IR Spectrum Peak Splitting: Symmetric vs Asymmetric Vibrations
Convolution Properties II
The width property indicates that if the durations of input signals are T1 and T2, then the width of the output response equals the sum of both durations, irrespective of the shapes of the two functions. For instance, convolving two rectangular pulses with durations of 2 seconds and 1 second results in a function with a width of 3 seconds.
The area property asserts that the area under the...
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
Convolution Properties I
The commutative property reveals that the input and the impulse response of an LTI (Linear Time-Invariant) system can be interchanged without affecting the output:

