[vtkusers] Dose Volume Histogram

[Scott Johnson]

Hello Xiaofeng,

 

You could minimize the partial volume by sampling into the dose grid at
the resolution of the CT voxels.  For example, you iterate through the
CT voxels for which you wish to create your DVH.  Map  the center of
that CT voxel position and sample into the Dose Grid to find the dose
value at that same position.  Then assume that dose value occupies the
entire CT voxel space.  That value goes into your DVH.

 

You can further minimize the partial volume effect by weighting the
voxels at the edges of your ROI.  As a swag, multiply the voxel weight
of an edge voxel by 0.5 .

 

Other than that you need to resample your dose grid at a finer
resolution still.  There is a computational tradeoff.

 

Hope that helps.

 

                                -- Scott

 

From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On
Behalf Of Xiaofeng Z
Sent: Thursday, October 14, 2010 1:10 PM
To: jothybasu at gmail.com
Cc: VTK
Subject: Re: [vtkusers] Dose Volume Histogram

 

I mean voxels that's partly inside and partly outside of the polygon.

Xiaofeng Z


 

________________________________

CC: karthik.krishnan at kitware.com; vtkusers at vtk.org
From: jothybasu at gmail.com
Subject: Re: [vtkusers] Dose Volume Histogram
Date: Thu, 14 Oct 2010 18:27:23 +0100
To: xf10036 at hotmail.com

What do you mean by partial volume?

 

Jothy

On 14-Oct-2010, at 5:48 PM, Xiaofeng Z <xf10036 at hotmail.com> wrote:

	Do you take into account of partial volume?  The dose grid is
typically very coarse, I don't think the partial volume can be ignored.
	
	Xiaofeng Z
	
	
	 

	
________________________________


	CC: karthik.krishnan at kitware.com; vtkusers at vtk.org
	From: jothybasu at gmail.com
	Subject: Re: [vtkusers] Dose Volume Histogram
	Date: Thu, 14 Oct 2010 17:23:47 +0100
	To: xf10036 at hotmail.com

	If you are speaking from the radiotherapy point of view,it
should be done in a different way from what krishnan told. You should
first use point-in-polygon method(which is available in vtkPolygon
class) to find the voxels inside the structure and using the voxel
indices, you could get their respective dose values and use a
binning/histogram to bin the dose values to get the dvh along with their
volumes.

	 

	Jothy
	
	On 14-Oct-2010, at 5:03 PM, Xiaofeng Z <xf10036 at hotmail.com>
wrote:

		Hi Karthik,  Thanks for your answer.  The problem is
that I also have a contour and only the volume (area) inside the contour
should be included the histogram.
		
		Xiaofeng Z
		
		
		 

		
________________________________


		Date: Thu, 14 Oct 2010 20:14:13 +0530
		Subject: Re: [vtkusers] Dose Volume Histogram
		From: karthik.krishnan at kitware.com
		To: xf10036 at hotmail.com
		CC: vtkusers at vtk.org
		
		No there isn't, but it should be relatively
straightforward. On your dose image,  run vtkContourFilter with
isovalues, that evenly split your scalar range into the desired number
of bins. Then use vtkMassProperties to compute the area within each dose
isocontour and use the charting capability to plot.

		On Thu, Oct 14, 2010 at 7:52 PM, Xiaofeng Z
<xf10036 at hotmail.com> wrote:

		Hello VTK users,
		 
		Is there a function to generate Dose Volume Histogram?
		 
		A Dose Volume Histogram is, in essence, a histogram of
the area vs. intensity within an arbitrary contour i.e. the contour
points are not always at pixel center.
		 
		Thanks!
		
		Xiaofeng Z
		
		

		
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