plastimatch

CXT file format

The cxt file format is an ASCII format that mirrors the DICOM-RT structure set format. The command “plastimatch convert” converts from CXT to DICOM-RT structure set.

The cxt file format contains the following sections

Header section Various flexible ascii fields
ROI section List of ROI’s in the structure set, along with a fixed set of information on each
Contour section List of contours, with a fixed set of information about each

The header section contains mostly information about the associated volume:

SERIES_CT_UID uid The uid field specifies the UID for the associated CT volume
OFFSET x y z The x y z fields specify the position of the first (upper left) voxel in the image
DIMENSION x y z The x y z fields specify the size of the volume
SPACING x y z The x y z fields specify the inter-voxel spacing

Each line of the ROI section contains three fields, separated by the ASCII space “ ”.

Field Value Example
Structure number A positive integer 1
Color RGB tuple, separated by backslashes 02550
Structure name ASCII string gtv_primary

Each line of the contour section has 6 fields, separated by the pipe symbol “|”.

Field Description Example
ROI Number A postitive integer, referring to the structure 1
Contour thickness This is included by GE dicom export. Not sure how useful it is 2.5
Number of points How many points in the contour? 3
Slice index Which slice does this contour belong to within the CT series of interest? The numbering start with 0 for the first slice sorted by Z. 20
Associated slice UID Which slice does this contour belong to within the CT series of interest? 2.16.840.1.114362.1.90609.1196125535718.935
Points Sequence of xyz tuples, separated by backslashes. Units are mm. z value should be the same for all of the points. 5.4-63.2108.4-66.2101.8-49.010