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. 2009 Jan;34(1):12-22.
doi: 10.4103/0971-6203.48716.

Comparative study of convolution, superposition, and fast superposition algorithms in conventional radiotherapy, three-dimensional conformal radiotherapy, and intensity modulated radiotherapy techniques for various sites, done on CMS XIO planning system

K R Muralidhar  1 , Narayana P Murthy, Alluri Krishnam Raju, Nvnm Sresty
Affiliations

Comparative study of convolution, superposition, and fast superposition algorithms in conventional radiotherapy, three-dimensional conformal radiotherapy, and intensity modulated radiotherapy techniques for various sites, done on CMS XIO planning system

K R Muralidhar et al. J Med Phys. 2009 Jan.

Abstract

The aim of this study is to compare the dosimetry results that are obtained by using Convolution, Superposition and Fast Superposition algorithms in Conventional Radiotherapy, Three-Dimensional Conformal Radiotherapy (3D-CRT), and Intensity Modulated Radiotherapy (IMRT) for different sites, and to study the suitability of algorithms with respect to site and technique. For each of the Conventional, 3D-CRT, and IMRT techniques, four different sites, namely, Lung, Esophagus, Prostate, and Hypopharynx were analyzed. Treatment plans were created using 6MV Photon beam quality using the CMS XiO (Computerized Medical System, St.Louis, MO) treatment planning system. The maximum percentage of variation recorded between algorithms was 3.7% in case of Ca.Lung, for the IMRT Technique. Statistical analysis was performed by comparing the mean relative difference, Conformity Index, and Homogeneity Index for target structures. The fast superposition algorithm showed excellent results for lung and esophagus cases for all techniques. For the prostate, the superposition algorithm showed better results in all techniques. In the conventional case of the hypopharynx, the convolution algorithm was good. In case of Ca. Lung, Ca Prostate, Ca Esophagus, and Ca Hypopharynx, OARs got more doses with the superposition algorithm; this progressively decreased for fast superposition and convolution algorithms, respectively. According to this study the dosimetric results using different algorithms led to significant variation and therefore care had to be taken while evaluating treatment plans. The choice of a dose calculation algorithm may in certain cases even influence clinical results.

Keywords: Algorithm; conformity index; homogenity index; treatment planning system.

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Conflict of interest statement

Conflict of Interest: None declared.

Figures

Figure 1a
Figure 1a
Hypopharynx 3DCRT - DVH with three algorithms
Figure 1b
Figure 1b
Lung - 3DCRT DVH with three algorithms
Figure 1c
Figure 1c
Prostate - 3DCRT - DVH with three algorithms
Figure 1d
Figure 1d
Esophagus - 3DCRT - DVH with three algorithms
Figure 1e
Figure 1e
Esophagus - OPEN Technique - DVH with three algorithms
Figure 1f
Figure 1f
Prostate - OPEN Technique - DVH with three algorithms
Figure 1g
Figure 1g
Hypopharynx - OPEN Technique - DVH with three algorithms
Figure 1h
Figure 1h
Lung - OPEN Technique - DVH with three algorithms
Figure 1i
Figure 1i
Esophagus - IMRT Technique - DVH with three algorithms
Figure 1j
Figure 1j
Lung - IMRT Technique - DVH with three algorithms
Figure 1k
Figure 1k
Hypopharynx – IMRT Technique DVH with three algorithms
Figure 1l
Figure 1l
Prostate - IMRT Technique DVH with three algorithms
Figure 2a
Figure 2a
Monitor Unit comparison in Carcinoma of Esophagus
Figure 2b
Figure 2b
Monitor Unit comparison in Carcinoma of Prostate
Figure 2c
Figure 2c
Monitor Unit comparison in Carcinoma of Hypopharynx
Figure 2d
Figure 2d
Monitor Unit comparison in Carcinoma of Lung
Figure 3
Figure 3
The difference in dose wash between Fast Superposition algorithm and Superposition algorithm in Ca. Prostate with IMRT technique
Figure 4a
Figure 4a
Dose wash with convolution, superposition, and fast superposition algorithms in ca.hypopharynx
Figure 4b
Figure 4b
Doses wash with convolution, superposition, and fast superposition algorithms in ca.lung
Figure 4c
Figure 4c
Dose wash with convolution, superposition, and fast superposition algorithms in ca.esophagus
Figure 4d
Figure 4d
Doses wash with convolution, superposition, and fast superposition algorithms in ca.prostate
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