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Convolution is one of several value-added software modules in the Leksell GammaPlan
portfolio. It enables extremely accurate dose calculation for the treatment of
heterogeneous tissue.
Accurate Dose Distribution – Anywhere
Convolution provides dose calculation accuracy that approaches the quality of a true
Monte Carlo algorithm.* It is specifi cally designed to rapidly generate dose plans for
heterogeneous tissue, such as tissue-air and tissue-bone interfaces.
Flexibility for Speed and Effi ciency
Convolution gives you freedom-of-choice and superb fl exibility, allowing you
to decide which dose calculation algorithm to use for a specifi c target. You can
choose TMR (Tissue-Maximum-Ratio) or Convolution for a specifi c target or
group of targets, depending on target location. Another option is to choose
one of these algorithms for all targets.
Total Confi dence
The accuracy that is possible with Convolution helps build confi dence,
while also giving you control. Choose your settings, change them at
will and maintain full control over the fi nal solution.
Leksell GammaPlan®
ConvolutionConfi dent Dose Calculation in Heterogeneous Tissue
Why Convolution?
• Precise dose calculation in
heterogeneous tissue
• Powerful complement to TMR
• Flexibility to choose TMR or
Convolution
*Based on the results of benchmarking comparisons between Convolution and Monte Carlo calculations.
Convolution is an accelerated multi-beam convolution algo-
rithm that models build-up effects and takes heterogeneity
of material into account. It uses Monte Carlo pre-calculated
fl uence planes for each beam calculated at the center of
a water phantom. The fl uence planes are scaled according
to depth and heterogeneity. The algorithm separates the
primary and the scattered secondary contribution for
calculation of the dose.
The primary dose is calculated by convolving the TERMA
(Total Energy Released per unit MAss) obtained from the
fl uence planes with an electron-density scaled primary kernel.
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Tel +46 8 587 254 00Fax +46 8 587 255 00
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Add-on
Inverse Planning
Convolution
Re-Treatment™
ColorPET™
Add-on
DICOM-RT
WarpSpeed™
FunctionalPlanning
ImageMerge™
LeksellGammaPlan®
Convolution – Overview
Convolution requires a full-head CT scan as input. It models build-
up effects as well as heterogeneity effects. The dose calculation is
separated into two parts: primary dose and scatter dose algorithm.
Convolution – for the Highest Calculation Accuracy in Heterogeneous Tissue
Elekta continues to add functionality to Leksell GammaPlan. Using the
latest technology, Gamma Knife® software modules bring more power to
your planning. This opens the platform for future upgrades and opportuni-
ties, while delivering on daily clinical needs for improved workfl ow, cost
effi ciency and treatment quality.
In order to gain simulation speed, the radiological lengths
are pre-calculated for many equally distributed directions at
every voxel and are used for each beam, thereby avoiding
the need to repeatedly refer to the electron density-table.
The dose due to scattering is calculated by convolving a
model-fi tted depth kernel with the TERMA at the central
axis of each beam. This scattered depth dose is then used to
scale a lateral scattering dose profi le.
Convolution relies on relative electron density defi ned from
CT images covering the entire skull. Conversion between
CT numbers and electron density values is performed via a
user-defi ned CT calibration curve (per CT scanner console).
Any electron density value outside the CT calibration curve is
truncated. While planning, truncated values can be displayed
during the defi nition of the electron density.
Dose convolution. Pfx 16mm shot
z (m
m)
AIR WATERx (mm)
High dose
Low dose
Dose comparison Convolution - Monte Carlo. Pfx 16mm shot
AIR WATER
Dos
e
90 100 110 120 130 140 150
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
Convolution
Monte Carlo
x (mm)