Hi all,Hi Dear John
I am trying to better understand the concepts behind DICOM RT-Dose
objects, and how they should be displayed by viewing applications
supporting DICOM RT objects.
What I understood until now (correct me if I am wrong) is that doses
can be expressed in terms of:
1) dose points or isodose curves: in this case, the elements which
should be displayed by a RT viewer application are described in the
DICOM dataset through the ROI Contour module, which basically
describes points, lines or polygons as a set of 3D coordinates in the
3D space of the patient.
2) does grid: in this second case, the dose values are described
through the Pixel Data data element. Here, pixel values actually
represent dose values, correct? A multi-frame Pixel Data attribute may
be present, and in this case each frame represent dose values for a
given "plane / slice", as specified by the "(300C,000C) - Grid Frame
Offset Vector" data element.
Is my understanding correct until now?
Ok, now I have a question:
I have some sample studies where multiple "RT-Dose" DICOM files are
present, each one having multiple frames in Pixel Data. Considering
all these RT-Dose DICOM files, I have several RT dose "pixel data"
frames (coming from different files) which apply to a given CT slice
(i.e., which belong to the same plane as the CT slice). Should I SUM
the dose values coming from each RT dose frame which apply to a given
CT slice in order to obtain the actual dose value which should be
applied to every pixel of my CT slice? Or how should I combine values
coming from different RT dose frames which apply to the same CT slice
(i.e., which have the same Grid Frame Offset value)?
In particular, I am considering the issue from the point of view of
the viewing application: I have seen applications which show the RT
dose which applies to each CT slice as a semi-transparent overlay area varying from blue for lower-dose zones to red for higher-dose zones (IsoShades). So in this case I guess the viewing application should
compute the "overall" dose which applies to a given CT slice. How are
the several RT-dose frames related to a given CT slice's plane
Any clarification would be greatly appreciated.
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