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 |