Hello BELHADJ wassim,<br><br>a region growing algorithm (probably using ITK) starting from the corners of your data to get rid of the "unwanted air" might prove useful to tackle your problem.<br><br>Regards, <br>
<br>Frederic Perez<br><br><div class="gmail_quote">On Tue, Feb 17, 2009 at 9:45 AM, <span dir="ltr"><<a href="mailto:wassim_belhadj@topnet.tn">wassim_belhadj@topnet.tn</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi,<br>
<br>
Thank you for your reply.<br>
<br>
According to Hounsfield Units, the pixel values that form the air is<br>
between -1000 <--------> -995.<br>
<br>
I want to display ONLY the lungs (not skin ...) so I set my function<br>
transfer like this:<br>
<br>
opacityFun->AddPoint(-3024, 0.0);<br>
opacityFun->AddPoint(-878.674, 0.0);<br>
opacityFun->AddPoint(-864.466, 1.0);<br>
opacityFun->AddPoint(-594.524, 1.0);<br>
opacityFun->AddPoint(-395.62, 1.0);<br>
opacityFun->AddPoint(3071, 0.0);<br>
<br>
Hounsfield Units for lungs are -950 <--------> -550<br>
<br>
I Attached a NEW screenshot that illustrates the problem.<br>
<br>
I vary the values of the transfer function but no result.I did not manage<br>
to remove the part that surrounds the lungs.<br>
<br>
Best regards,<br>
BELHADJ wassim<br>
<br>
<br>
<br>
<br>
<br>
On Tue, 17 Feb 2009 18:06:18 +1100, Kevin Osborn <<a href="mailto:planck@netspeed.com.au">planck@netspeed.com.au</a>><br>
wrote:<br>
> Don't forget air surrounds the patient. What your image shows is the<br>
> air/skin interface, not the skin itself. As the lung is mostly air, your<br>
> Hounsfield range between -600 and -400 not only gives lung but also<br>
> includes air around the patient.<br>
><br>
><br>
> <a href="mailto:wassim_belhadj@topnet.tn">wassim_belhadj@topnet.tn</a> wrote:<br>
>> Hi,<br>
>><br>
>> I'am using VTK/VTKEdge and QT4 for volume rendering.<br>
>><br>
>> I 'am using a CT Datasets of a young person ( 35 years old)<br>
>><br>
>> I'm trying to define values of pixel that define lungs.<br>
>><br>
>> I assigned opacity to each pixel by checking its intensity value with<br>
>> Hounsfield Units values.<br>
>><br>
>> Bone +400 -----------> +1000<br>
>><br>
>> Soft tissue +40 -----------> +80<br>
>><br>
>> Fat -80 -----------> -100<br>
>><br>
>> Lung -400 -----------> -600<br>
>><br>
>><br>
>> I got a strange result !! The volume obtained contains the lungs and<br>
>> skin<br>
>><br>
>><br>
>> According Hounsfield Units, the pixel values that form the skin and<br>
lungs<br>
>> are not in the same interval.<br>
>><br>
>> I varied the opacity values to eliminate the skin that surrounds the<br>
>> lungs<br>
>> but I have not succeeded.<br>
>><br>
>> Attached a screenshot that illustrates the problem.<br>
>><br>
>> Can someone help me ?<br>
>><br>
>> Best Regards,<br>
>> BEHADJ wassim<br>_______________________________________________<br>
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