User Manual

The IDEAL workflow

An independent dose calculation with IDEAL

There are different user interfaces for IDEAL, but the basic workflow is always as follows:

• User starts user interface with username and role

• User provides DICOM input data (CT, RS, RP, RD) * For instance by exporting them from the TPS as DICOM files on a shared file system.

• User chooses MC settings:

  • required: statistical goal (number of primaries, uncertainty, time out, or a combination of these)

  • optional: CT protocol [1] (required if CT protocol is not automatically recognized).

  • optional: material overrides (default: only G4_AIR for volume outside of external)

  • optional: spatial resolution overrides (default: same as TPS dose)

  • optional: which beams to simulate (default: all of them)

• GATE-RTion Simulation runs on the cluster (typically for a couple of hours, the actual runtime depends on many factors)

• Beam dose distributions are exported by IDEAL as DICOM files (and MHD format, if configured that way)

• User analyzes and evaluates dose distributions using third party tools (e.g. [VeriSoft] or a TPS like [RayStation])

For a user in a light ion beam therapy clinic, this workflow is illustrated in figure below.

Longer term work flow

1. You work in an proton/ion beam therapy clinic and decide that Geant4-based independent dose calculations may be useful in your clinic.

2. A sufficiently powerful and extendible computer cluster is acquired, with resources as described in System requirements.

3. IDEAL is installed on this cluster as described in IDEAL installation by an employee with an admin role.

4. The medical physicist(s) with a “commissioning” role develops the beam model(s), installs the CT Hounsfield lookup tables and edits the system configuration file with correct values.

5. The medical physics team runs a series of tests to make sure that the installation went well. This should probably include:

• Integrated depth dose curves for several energies in water (using a CT of a water phantom)

  • compare with measurements (both the shape of the curve and the absolute dose)

  • determine/adjust correction factors

• Beam profiles in air, compare with measurements

• Example treatment plans from recent clinical practice:

  • Check level of agreement, find any systematic offsets in dose or in geometry

  • Determine cluster performance:

    • how does the simulation runtime vary with statistical goals and with complexity of the plan (number of beams, number of spots, radiation type, etc)

    • are there any crashes (e.g. due to insufficient memory)?

  • Check all combinations of beamline, radiation type, passive elements and CT protocol that you expect to use

• You are yourself responsible for the correct use of IDEAL and any consequences of using its results. If you intend to use IDEAL clinically, then you need follow all procedures for using “Software Of Unknown Provenance” (SOUP). IDEAL is NOT a medically certified product.

6. Use IDEAL to perform independent dose calculations in your clinic or for research.

   • The commissioning physicist should make sure that the commissioning data are correct and up to date. Whenever new beamlines or CT protocols are introduced or the existing ones are changing, the commissioning data should be updated.

   • The admin should make sure that the disks do not fill up, by regularly purging data from older simulations.

   • Periodically review the performance of your IDEAL installation:

     • with experience you may improve some choices made during installation and commissioning

     • buy more cluster nodes, more RAM (and update the System configuration file)

     • share your observations, experiences and ideas for improvement with the IDEAL development team

[1]

The CT protocol selection may be automated in later release, but the users will still be able to override the protocol.

Requirements and limitations on DICOM input

What kind of treatment plans can be studied using IDEAL?

• The input treatment plan should be a plan for scanning ion beam treatment. IDEAL is not designed to work for e.g. passive scattering proton therapy and conventional radiation therapy with photons.

• IDEAL takes the DICOM plan file as input, and expects to find the following DICOM files in the same directory (or in subfolders): * Structure set file, with the SOP Instance UID that is referred to by the treatment plan, * CT files, with the Series Instance UID that is referred to by structure set, * TPS dose file(s), which refer to the SOP Instance UID of the treatment plan.

• Hounsfield lookup tables for the protocol that was used for the input CT should be available under CT protocol Hounsfield Lookup tables in the Commissioning Data Directory.

• Beam line model for the ‘Treatment Machine’ should be made available under Beam line modelling in the Commissioning Data Directory.

• In case multiple TPS dose files are found (physical and/or effective dose, dose per beam and/or dose for the whole beamset) it is important that all have the same geometry (origin coordinates, voxel size a.k.a. “spacing”, number of voxels in each dimension a.k.a. “image size”).

Full details of how IDEAL uses DICOM can be found in the DICOM specification.

Details per user interface

Command line interface: clidc.py

The name clidc stands for: Command Line interface for Independent Dose Calculation with “IDEAL”.

The command is run in a bash shell environment (or equivalent, a Z-shell probably also works). In order to set up the environment to make it work, the user should first run source /path/to/IDEAL/install/bin/IDEAL_env.sh, where /path/to/IDEAL/install should obviously be replaced with the actual directory path where IDEAL was installed [2].

Ways to call this script:

• Get help, remind yourself of all the possible options:

  clidc.py --help
  

• Query which hardware is supported (by the commissioning physicist) in the current installation:

  # print the list of supported CT protocols, modelled phantoms, override materials and beamline names.
  clidc.py -C -P -M -Z
  

• Query a plan:

  # query a specific treatment plan, to print to stdout:
  # * list all ROIs in (the structure set used by) a plan
  # * the default size (number of voxels) of the dose distribution
  # * the list of beam names in the plan
  clidc.py -R -X -B /path/to/some/RP_treatment_plan.dcm
  

• Configure & submit a plan for independent dose calculation:

  # you need to provide at least one statistics goal and a treatment plan filepath
  # you need to provide EITHER a CT protocol OR a phantom name
  # tweaks are optional
  clidc.py -l user_role \
       [statistics options] \
       [ -c CT_protocol | -p phantom ] \
       [ configure tweaks ] \
       /path/to/some/RP_treatment_plan.dcm
  

So there are basically four groups of options:

General options (lvsjd)

These options can be combined with any of the other options.

• -l: “login” or “username and role”. This option specifies the username and role under which you would like to run clidc.py. The username and role is part of the output dose files. Some configuration options can only be used with commissioning role (e.g. make the beamline model than the default model for the TreatmentMachine). The default value for -l is the Linux user name under which the clidc.py script is run. User names are roles are configured in the System configuration file.

• -v: This option causes the debug level output of the query or job submission to be printed to standard output. Default is to print only the info level (which is already quite verbose). The verbose logging output can always be read in the log file that is written for every invocation of clidc.py in the logging directory.

• -s: With this option you can run clidc.py with an alternative system configuration file. This can be useful for commissioning/research. Default system configuration file is the cfg/system.cfg file in the directory where IDEAL is installed.

• -j: Number of cores to use per beam. Default: the number of cores specified in the System configuration file.

• -d: This option is currently a no-op. The intention is that when set, the temporary data generated by the simulations will not be compressed/deleted, so that it remains available for diagnostics and debugging by the user/developer/researcher. Currently, the temporary data are always compressed, unless the postprocessing script crashes before it gets to perform that operation.

Query options (with a uppercase letter: BCMPRXZ)

These cause clidc.py to perform a query instead of a dose calculation. These options cannot be combined with the following two groups of options (configuration tweaks and statistics goals).

• -B: beam names in a treatment plan

• -C: available CT protocols (Hounsfield lookup tables)

• -M: available override materials

• -P: available phantom models

• -R: ROIs in (the structure set that is used by) a treatment plan

• -X: default dose resolution (number of voxels in each direction)

• -Z: available beamline models (useful for commissioning and research)

Statistical goal options (with a lowercase letter: tnu)

These cause clidc.py to perform a dose calculation and cannot be combined with query options.

• -t: maximum time to run (excluding queue waiting, pre- and post-processing time) in minutes.

• -n: minimum number of primary particles to simulate.

• -u: average uncertainty to reach (or better) in the voxels that have at least half the maximum dose.

More details below.

Configuration options (with a lowercase letter: bcmpxz)

These options change the way how clidc.py to perform a dose calculation and cannot be combined with query options. Note that for each uppercase query option BCMPXZ that queries a quantity/property there is a corresponding lowercase configuration option bcmpxz that changes the value/setting of that quantity/property. (The information queried with R is used in the m material override option, so there is not separate r tweak option.)

• -b: beam names to simulate (instead of all beams in the treatment plan)

• -c: CT protocols (Hounsfield lookup tables) to use

• -m: followed by one or more values of the form ROINAME:MATERIALNAME, to specify material overrides.

• -p: specify phantom to use INSTEAD of the CT

• -x: changes the dose resolution (number of voxels in each direction; the origin and physical size remain unchanged).

• -f: score dose on full CT resolution, do not resample to the TPS planning dose

• -z: use this beamline model for all beams in the plan (only available with commissioning and research roles)

The -c and -p are mutually exclusive, as are -x and -f.

Examples of all 7 possible combinations of the three statistical constraints/goals:

-n 1000000: stop when >1000000 primaries were simulated.
-u 1.5: stop when average statistical uncertainty in the high dose region is <1.5%.
-t 18000: stop after running for >5 hours.
-n 1000000 -u 5: run >1000000 primaries, and then continue running until <5% uncertainty is reached.
-t 18000 -u 4: try to reach <4% uncertainty, but stop if it takes >5 hours.
-t 18000 -n 1000000: try to simulate >1000000 primaries, but stop if it takes longer than 5 hours.
-t 18000 -n 1000000 -u 2.0: stop after 5 hours, unless the goals of running >1000000 primaries AND <2% average statistical accuracy have been reached earlier.

The constraints are not checked after every individually simulated primary. Rather, they are checked periodically (e.g. every two minutes, this can be configured). This means that the constraints will typically be exceeded by a bit: you may get a couple of thousand primaries more than you asked for, the simulation may keep running for a while after the timeout has expired and/or the average statistical uncertainty may be slightly better than the goal.

Todo

Describe better how the average dose uncertainty is computed. There is some explanation buried in the system configuration file docs, but that is in the install/commissioning part. It should actually be explained in the “usage” part of the manual.

[2]

Once IDEAL has been fully “pip”-ified, this sourcing step might not be necessary any more.

PyQt interface

More details.

Research interface

More details.