ReadDicomCheck

Run the program ReadDicomCheck to import plans in Dicom RT format to Dosimetry Check. Run the program from the current directory type typing:

ReadDicomCheck

on unix systems. On Windows, you should find the program under the Start menu. Below is a picture of the popup for this program.

This program will read in Dicom RT files and write out the patient directory with the plan for Dosimetry Check to pick up. The planning system should write out the plan into Dicom RT files, which are then read. Either navigate to the directory where these files are, or copy them into some convenient directory. By default, the file selection box starts in the directory where it expects to find image files as defined in the file NewDicomRTDirectory.loc in the program resources directory, or if that file is not present, then the file NewImagesDirectory.loc. The CT scans will be each in a separate file. The outlined region of interest structures, plan, and 3D dose matrix will typically be in different files. These files may or may not start with convenient prefixes, such as the structure file starting with the letters RS, the beam geometry in a file starting with the letters RP, and the 3D dose matrix in a file starting with the letters RD. After reading in the Dicom RT files, run Dosimetry Check and select the patient directory created here, and then the plan created here. Below are comments on running the program ReadDicomCheck.

Patient

You have to first create a patient. If you don't know the patient's name you can get it from any CT scan file using program DicomDump in the tools.dir directory respectively. This program is an ASCII program. Invoke with the program name followed by the name of the CT scan file to read. You might want to pipe to the more function, for example:

DicomDump file_name | more

Other Dicom display functions can be found on the internet.

Create the patient if a new patient or select an existing patient. It is your responsibility to guarantee that the images and plan belong to the correct patient, and that the plan is for the stacked image set selected.

Stacked Image Set

You next have to select an existing stacked image set or read in a new one. The plan to be read has to be for the stacked image set. If creating a new stacked image set, use the filter on the file selection box to read in only scan files, for example, by setting the filter to CT*. Then select all files to read in. This program will here allow you to only select or read in one stacked image set. This stacked image set is the primary image set for the plan which supplies the external body outline and the CT number to density conversion function.

CT number to Density Conversion

There is no mechanism in Dicom RT for specifying how CT numbers are converted to density. Therefore you will still have to provide a conversion for Dosimetry Check. After running Dosimetry Check and picking up the patient and stacked image set, go under StackedImageSets to Options to Density and select a conversion curve or create a new one.

Regions of Interest (ROI)

Once you have read in the stacked image set you should read in outlined regions of interest (ROI). There is a mechanism for identifying which ROI is the external body outline. However, if that fails or is absent, you will have to select the body outline or create it in Dosimetry Check. To create a body outline, use the tool for that purpose under Contouring. To select an existing body outline, go under StackedImageSets to Options to Skin. You might want to check the choice as a matter of routine.

Generally the Dicom RT ROI file starts with the letters RS.

Plan

Once you have the stacked image set, you can read in a plan. Here we only pick up the beam positions (gantry, collimator, and couch angles, and isocenter location) and 3D dose matrix. First select to read in the beams. You must read in the beams first and then select to read in the dose matrix second. You cannot read in the dose matrix without reading the beam file first at the same time. This is because there is information about the plan in the beam file that is needed by the dose matrix function that is not provided in the dose file. There is a check that the dose file is for the selected beam file.

Generally the Dicom RT beam file starts with the letters RP and the dose file with the letters RD.

Beams

If the accelerator machine name is not one that exist in the treatment machine directory, you will be prompt to select the accelerator that the beams are to use. This choice will apply to all the beams. Naturally the selected machine must have the required energy. Dicom RT specifies the accelerator coordinates in IEC coordinates, which is also the system for Dosimetry Check, so no conversion in needed. The Geometry file in each machine directory simply specifies how the coordinates are presented to the user. For example, for a non-IEC accelerator, the gantry angle will be converted from IEC to the system specified in the Geometry file when presented to the user. Changing the Geometry file will therefore not change the actual angle of a beam, only the angle reported to the user.

Dosimetry Check

After reading in the plan, exit the program and run Dosimetry Check. Select the patient, stacked image set, and then the plan. For each beam you must read in a fluence dose file. Dosimetry Check shows the dose in the resolution selected under Evaluate. For example, if Dosimetry Check has the default value of 0.5 cm, then a matrix of that spacing is provided for any selected plane. Doses are interpolated out of the 3D dose matrix read above. If the imported 3D dose matrix has a spacing of 0.1 cm and the above is set to 0.5 cm, you will see the isodose curves plotted on a 0.5 cm matrix. There is an option under Evaluate on the Plan toolbar to show just the dose from the treatment planning system. Dosimetry Check could thus be used as a tool to display plans from other systems.