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planning:userguide:walkthroughs:prostate_plan

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Table of Contents

Prostate Plan Walkthrough

Patient Creation

  1. Select the CT image set from the list of available files for import
  2. Ensure that the MR is correct
    1. If MR needs to be changed you may edit it by choosing the Edit button to the left
  3. Click the Create New Patient button to start the import process
  4. Fill in the Patient Intent information and select the appropriate HU to RSP curve (as shown below)

  5. Click the Create Patient button and wait for the import to complete
  6. Click the Back to Imports button

  7. Select the Structure Set file that is associated with this patient
    1. Make sure Structure Set MR matches CT image set MR (make any edits to the MRN that are needed)
  8. Click the Import into Patient button in the patient information window

  9. In the control pane on the left hand side, the image snapshot will be automatically selected based on the structure set DICOM UID information, and then the Import Structure block will automatically expand.

  10. You will see a list of the imported structures. Here you may choose whether or not to import each structure by checking or unchecking the box beside each structure name.
    1. For this case, we will import all available structures and there is nothing to change on this page
  11. You also have the ability to assign or edit any structures that are shown as custom, which indicates the name did not exactly match a directive structure from the treatment site template list you specified during patient creation.
    1. Matched, Assigned, and Custom structures are designated with corresponding tags at the end of the structure name in the structure list.
    2. Assigning a custom structure to a defined directive structure will result in the imported structure inheriting all the predefined structure properties (e.g. name, type, color)
    3. For all custom structures the type is by default set to “Other” unless it contains the letters “TV” (as in PTV or CTV), in which case it is assigned the type of “Target”; this may be changed here if needed
  12. Once you have completed explored this feature, make sure all structures are back to their default states and click the orange “Import Structures” button (see above image)

Prescription

  1. The patient is now created and all available data has been imported, so it is time to proceed with entering the prescription information
  2. Click on the Back to Import button
  3. Click the Planning task
  4. Click the entry from the table of patients that corresponds to your newly imported patient
  5. Prescription information is stored in the Directive
  6. Click Open under the Directive entry in the patient overview tree
  7. Under General fill in Goals
    1. In this example we will set a minimum dose to the PTV7920 at 79.2Gy and the maximum dose at 85.5Gy as shown below

  8. Next proceed to Phases and fill in Fractions and Prescription
    1. For this example the dose will be 79.2Gy in 44 fractions to the PTV7920

    2. Label and Description are free text fields that allow you to “name” each Phase and provide any description or notes necessary to distinguish between each phase in the case of multiple phases. You are free to enter your own values in these fields for this walthrough
  9. Click Create to complete the phase
  10. Click Done to complete the Directive editing and return to the Patient Overview tree

Plan Creation

  1. The required Intent, Course, and Snapshot information was selected during import, so now we can move to creation of a Request and Plan
  2. From the Patient Overview tree, click the Add Request button
    1. If a plan will only fulfill a portion of the prescription, then the Request should be edited to reflect this, otherwise just proceed to adding a plan
    2. In this case, we will be fulfilling the entire prescription with a single plan, so no editing of the Request is needed
  3. Now click the Add Plan button under the newly created Request entry
    1. Name the plan and click Save
  4. Now open the new plan by clicking the Open button under the new plan entry in the Patient Overview tree

General Plan Parameters

  1. Creating our plan will begin in the Patient Geometry block, where we will create any points or planning structures that are needed (if not created in contouring software), such as a combination of the left and right femoral heads (see Structure Geometry for details on how to Create structures)
    1. We will create a point to use for the isocenter (note this step is done for illustration purposes and is not necessary for most plans)
      1. Select a type of isocenter and create the point at the centroid of the prostate

  2. Next we will move on to defining the HU to Proton Relative Stopping Power (RSP) conversion
  3. Click to open the RSP Image block
    1. If any density overrides are needed they are entered here in the RSP Image block
    2. If the HU to RSP curve was not chosen upon patient import the user may do so at this point
    3. We do have any density overrides to apply for this case and the proper HU curve has already been selected, so we can move past this block for this example, so click Cancel to close this block
  4. We are now ready to define the dose calculation grid (see Defining the Dose Grid for a detailed explanation)
  5. Click to open the Calculation Grid block
    1. Create a grid by performing the following steps:
      1. Set the base grid resolution to 8 mm
      2. Click Add Structure and select the “2cm” structure
        1. Set the size to 4 mm
      3. Add the PTV and the Prostate each in the same manner and set their sizes to 2 mm

Beams

  1. We are now ready to begin defining the treatment beams
  2. Click to expand the Beams block (see Creating a New Beam for detailed explanation)
    1. Before defining individual beams, we will first set some shared beam properties
    2. Set the Treatment Room by choosing “Gantry 2” from the dropdown

    3. Expand the Spot Placement sub-block and set the following values (note these are the plan level spot placement parameters, so it will apply to all our beams, unless we specifically override the values within an individual beam)
      1. Lateral margin- 15 mm
      2. Distal margin- 10 mm
      3. Spot spacing- 1 sigma
      4. Layer spacing- .8 Distal W80

    4. Now we are ready to make our beams
    5. Start by clicking Create New Beam
      1. Enter the following for each beam
        1. General
          1. Select the PTV as the target and if desired, enter a description for the beam, for other selections leave the defaults (see Structure Geometry)
        2. Approach
          1. At this point the user will specify the geometry of the beam by setting the isocenter as well as the gantry and couch angles
          2. Two beams at gantry angles of 90 and 270, respectively, will be used here, which is typical (+/- 5 degrees) for standard prostate plans such as this example
          3. Couch angle of 0 is used here for each beam
            1. You may use the sliders, the +/- buttons, or simply type in the values to adjust these angles

        3. Snout
          1. Depending on the size of the prostate a 10-12cm snout should be adequate, in this example select the 12cm Snout option
          2. If the pelvic nodes need to be included, the user may need to increase the snout size to the 18 or 25cm snout

        4. Aperture (if desired)
          1. If there is the need to use an Aperture for sharper penumbra the user can do so at this time (see Creating an Aperture)
          2. Note that Astroid has the ability to utilize an Aperture with pencil beam scanning for both SFO and IMPT plans
          3. For this plan, no apertures are necessary
        5. Shifter
          1. Simply choose a shifter from the list if one is needed
          2. For this plan, no shifters are necessary

        6. Air gap
          1. The air gap is specified as the distance from the final beamline device (aperture or shifter) or the snout end if no devices are present
          2. The view automatically shifts to the 3D view when entering this sub-block and you can adjust the air gap to ensure patient collisions are avoided
          3. The default air gap of 30 mm is sufficient for both beams in this example
        7. Spot placement
          1. Since we want both beams to use the same spot settings, we have those at the plan level and there is no need to edit the spot placements here for the beams
        8. DRR options
          1. The Proton DRRs shown in the Beam task are generally used to help determine appropriate treatment angles
          2. In cases such as these, appropriate angles are readily determined and there is no need to utilize the DRR sub-task
            1. If you wish to explore this feature however, you may choose one of the preset Density Presets from the drop down or manually set the level, window, min HU and max HU or go into Advanced Options for additional control of the DRR's
            2. These proton DRRs are used only for visualization purposes and will have no effect on the plan construction process

      2. Click Create to complete the first beam
      3. After creating the first beam (at gantry angle 90) it is recommended that you Clone it and simply change new beam's ganry angle to save time in creating the second beam (the Clone button is available under a beam when it is selected for viewing from the list of beams)
        1. Note for more complex plans, there are often additional parameters to change (such as the aperture and the air gap) when creating additional beams via the Clone option

Optimization

  1. With the two beams completely defined, we can now move on organizing our treatment fraction groups and specifying the constraints and objectives for the treatment
  2. Open the Optimization block (see Astroid Optimization for a detailed explanation of Optimization, Feasibility and Constraints, as well as Running the Optimizer)

Fraction Group

  1. Create a New Fraction Group under the Fraction Group block (See Fraction Groups for a more detailed explanation)
    1. Enter a Fraction Count of 44
    2. Add a new Target to the Target List by clicking Add Another Target
      1. Set the Target to the PTV
      2. Add the following Beam Set
        1. In this case we will use an IMPT approach so add both the G90 and G270 beams in this same beam set
      3. Constraints associated with this target
        1. Click the Add Structure drop down and choose the PTV
        2. Add a min dose constraint of 79.2 Gy (1.8 Gy per fx)
        3. Add a max dose constraint of 87 Gy
      4. At this point your Fraction Group should appear as shown below

    3. Click Create to complete the Target entry and then Create again to complete the Fraction Group

Constraints and Objectives

  1. This is our only Fraction Group for this plan, so we'll move on to the plan level constraints and objectives
  2. Open the Plan Constraints/Objectives block
    1. First we'll enter the Constraints for the planning (target) volumes
      1. Remember these are the “hard stops/non negotiables” for the plan
      2. These doses will be decided per the users' department protocols
      3. For this case do the following:
        1. Click Add Structure and select the Prostate
          1. Add a min set to 79.2 Gy
          2. Add a max set to 87 Gy
        2. Click Add Structure and select the PTV
          1. Add a min set to 75.2 Gy
          2. Add a max set to 87 Gy

After the target constraints have been entered, it's generally good practice to test the plan feasibility. The Feasibility calculation is run by clicking calculate in the Feasibility block at the bottom of the Plan Constraints/Objectives sub-block. The Feasibility calculation is based solely on the constraints and it should be used to ensure there is a possible solution (plan) that can meet the specified constraints. The Feasibility calculation may be an iterative processes in order to get appropriate constraints established for a particular plan. In other words, the user may need to enter a constraint, check the feasibility, then progressively tighten the constraint and check the feasibility until the plan is no longer feasible. It is recommended practice to start by obtaining a feasible plan utilizing only target constraints then add OAR constraints as desired. Remember, using a narrow range of constraints can improve the optimizer performance and improve the resolution of the Pareto surface navigation.

  1. Run the Feasibility by clicking the calculate link

    1. The feasibility should return as passing, if not, please confirm your plan parameters match those shown throughout this walkthrough and try again
  2. Now with the target constraints set, we'll move on to our OAR's
    1. Again these will be set per department protocol
    2. For this example create the following OAR constraints:
      1. Rectum max mean 60 Gy
      2. Bladder max mean 60 Gy
      3. Skin max 82.5 Gy
      4. Skin max mean 50 Gy
  3. Run Feasibility again
    1. The feasibility should return as passing again, if not, please confirm your plan parameters match those shown throughout this walkthrough and try again
  4. With narrow constraints set and feasibility established, we will now turn our attention to Objectives
    1. Objectives are the goals that you would like to achieve and these will be the driving forces for the optimizer
    2. Click Edit under the Objectives section
    3. For this example we will use the following objectives:
      1. Rectum min_mean (Minimize the mean dose to the Rectum)
      2. Prostate max_min (Maximize the minimum Prostate dose)
      3. Testes min_max (Minimize the maximum dose to the Testes)
      4. Left & Right Femur min_overdose 45 Gy (Minimize the amount of the structure the receives dose above 45 Gy)
      5. PTV min_max (Minimize the maximum dose within the PTV)
      6. PTV max_min (Maximize the minimum dose within the PTV)

  5. Click Done to complete the Objectives
  6. We are now ready to run the MCO, by opening the Navigation sub-block and clicking the calculate link
    1. This may take up to 20 minutes for this plan depending upon your available cloud services resources
    2. Keep in mind that even though this process may take some time the planner will be able to make adjustments easily in the Navigation without running a new plan
  1. Once the MCO has been completed, you can adjust the relative importance of the objectives using the slider bars in the Navigation block (see Astroid Optimization Navigating the Solutions for a detailed explanation of using the slider bars)
    1. Adjust the slider bars in the Navigation block to find what you feel is the optimal plan for this case
      1. Note: All of these adjustments are made without having to run a new plan
    2. If you find a plan that you like, but wish to continue exploring further, you can click the Save button to save the current slider state and then continue exploring
    3. You may return to the last saved state at any time by clicking the Reset button
    4. The Cancel button will close the navigation block, reverting back to the last Saved state

  2. The plan is ready for physician review at this point
    1. Physicians often find it useful to Navigate the solution and explore trade-offs in real time, which can often alter the traditional physician approval process into an interactive, real-time trade-off analysis and on the spot plan approval
  3. After the physician has decided on a treatment plan the user may then proceed to export the chosen plan to the EMR
    1. Note that these standard (non-plan specific) features are covered in other guides and not repeated herein
planning/userguide/walkthroughs/prostate_plan.1477415863.txt.gz · Last modified: 2021/07/29 18:25 (external edit)