BASIC TUTORIAL (NO IMAGES, updated for PS6 v6.7.7)

This tutorial takes you through a simplified, IMAGELESS planning session for a hypothetical 6 mm tall tumor with a circular base that is to be treated using a COMS plaque for an implant duration of 1 week (168 hours). The planning process follows the following progression:

  1. Enter patient identifiers.
  2. Enter the implant schedule.
  3. Enter tumor size and height.
  4. Position the tumor.
  5. Prepare the plaque window.
  6. Choose a plaque file.
  7. Center the plaque under the tumor.
  8. Create a new radionuclide inventory.
  9. Load the plaque.
  10. Enter Rx and calculate required source strength.
  11. Select a legend for plotting isodose lines.
  12. Calculate 2D planar and retinal dosimetry.
  13. Calculate dose histogram.
  14. Print the plan.
  15. Save the plan.
  16. QA review.

Tutorial file

The tutorial file Basic.iplan6 can be found in the folder (Tutorials)/PS6/Basic Tutorial which is located in your Plaque Simulator Patients folder which is initially located in the Documents folder of the Plaque Simulator OSX user. These files and folders were installed as part of your original installation or update of Plaque Simulator. (Eye Physics recommends eventually moving the Plaque Simulator Patients folder and all DICOM image storage to a PCIe or thunderbolt connected, encrypted external SSD to preserve as much free space as possible on your boot drive. The location of the Plaque Simulator Patients and Current Patients folders can be set as a PS preferences setting).

This tutorial outlines the steps required to create Basic.iplan6.


Step 1: Enter patient identifiers
  • From the Plan menu select Patient IDs.... PlanMenuPatientIDs
  • In the Patient IDs window enter the patient name and any other pertinent information. Items labeled with red text indicate fields that will generate alerts if not completed before printing a treatment plan.


Step 2: Enter the implant schedule
  • From the PSWindows menu select Prescription. WindowPrescription1
  • Enter the scheduled date and time of plaque insertion and removal, or alternatively, plaque insertion and implant duration.
  • You can enter the implant schedule using the textual time-date fields or using the graphical calendar sheet by clicking the calendar button.CalendarButton
  • In this special example notice that the plaque is inserted on a Wednesday at 10 AM with a specified duration of exactly 168 hours (1 week) yet the removal time the following Wednesday is 11 AM. This is because a daylight saving time shift occurs (note that March 14th is flagged in the calender sheet using a special icon) during the course of the implant.

Entering the implant date here in step 2 simplifies later creation of new radionuclide source inventories which will inherit this calibration date.


Step 3: Enter tumor size and height
  • From the Window menu select Retinal Diagram. WindowRetinalDiagram
  • In the Retinal Diagram toolbar, use the Eye control to choose the right eye.
  • From the toolbar Tumor control select tumor #1.
  • In the Retina window left side controls group click the Std. StdButton42x42 button to open the standard tumor sheet.
  • Enter radial and circumferential dimensions of 12.0 mm for the tumor base and 6.0 mm as the apical height of tumor in the Standard Tumor Dialog.
  • Click OK to exit the sheet.

We will assume that funduscopic examination and ultrasound studies have measured a 6mm (as measured from the internal sclera) tall tumor with a 12mm diameter circular base.


Step 4: Position the tumor
  • In the Retinal Diagram toolbar, set the Mouse Cursor Function to drag tumor.
  • The tumor base is indicated by the translucent tan region bordered by a brown line. It is surrounded by a two tone brown-green line illustrating a 2 mm "PTV" margin.
  • The default tumor is centered at the equator on the 9 o'clock meridian.
  • Click the cursor on the tumor base and drag the tumor to center it near the 10:15 meridian at about -41 degrees posterior latitude on the diagram as illustrated.
  • You could also specify the coordinates in the Standard Tumor Dialog as illustrated in step 3 above, but dragging the tumor on the diagram is the more typical method.

Step 5: Prepare the plaque window

Select the Plaque window from the PSWindows menu. In this example the COMS14 plaque file has been set as the default plaque at time of launch in PS6 preferences so the window is primed with that model plaque.

  • In the toolbar controls select Plaque #1.
  • In the next step we will select a different plaque to better fit this tumor size and shape.

Step 6: Choose a plaque file

From the Plaque menu select Rental Plaques.


Select the COMS rentals menu.


Select the file COMS16-p-r.iplq6. The -p tag indicates this plaque file embeds a picture of the plaque. The -r tag indicates it is a model that can be rented from IsoAid.


The COMS16mm plaque is being selected because according to the COMS plaque selection protocol the diameter of a COMS plaque is to be the maximum diameter of the tumor base (12 mm) plus 4 mm (representing a 2 mm margin surrounding the tumor base).

The dose calculation method and TG43 modifiers recommended by Eye Physics for the selected plaque are automatically set in the Prescription window when you create a standard plaque from one of the plaque menus or open a plaque file. You may, of course, override the recommended dose calculation settings should you need to and/or you can create your own plaque files with customized settings.


Step 7: Center the plaque under the tumor
  • In the Retina window left side plaque controls group click the Center button.

  • This will center the plaque under the base of tumor #1 and rotate the plaque about its central axis to balance the distance of its eyelets with respect to the limbus circle.

  • In this example, the 2nd and 5th eyelets (which are the default balancing eyelets for this plaque) are positioned on the 11:16 and 9:15 o'clock meridians, each 12.8 mm chord distance from the limbus as measured on the outside of the eye using a caliper.

Step 8: Create a new radionuclide inventory
  • From the Plaque window click the Source button to open the radionuclide inventory window.
  • To create a new entry in the inventory database click the Show only radio button to enable physics model selection.
  • Select a seed physics model from the menu. In this example model IAI-125A (IsoAid) has been selected. This physics model is designed for source strength to be entered in units of mCi as described in the Physics Dose Constants section.
  • Click the New button to create a new inventory entry.
  • The new entry will automatically be selected (highlighted in blue in the scrollview). It will inherit the currently specified implant date and time as its calibration, will be named for the current patient and will contain the number of sources in the currently active plaque (plaque #1, a COMS16mm model, was selected as currently the active plaque in step 5 above). The source strength will be initialized to 1.0 (either mCi or U depending upon the physics settings for the model seed selected).
  • Click the Edit button to review or change the selected inventory entry parameters.




Step 9: Load the plaque
  • In the Plaque window click the Load button to install a seed from the currently selected inventory in every source placeholder.
  • Click the Labels button to display the source strength.
  • You can use the mouse cursor functions to load, select and edit individual source placeholders in order to customize plaques and create intensity modulated source distributions (for example, in the manner of historic Patterson-Parker "Manchester System" planar implants).

Step 10: Enter Rx and calculate required source strength
  • From the PSWindows menu select Prescription. WindowPrescription2
  • In the Prescription window, click the Implant Calculator button to open the Implant calculator window.

  • The default prescription is 85 Gy (set in preferences) to the apex of the active tumor (tumor #1 was selected in step 3 above) which is a good choice for a 6 mm tall tumor.

  • Note: tumors < 5 mm tall often require either setting the prescription to a point on the plaque or tumor axis that is higher than the tumor height, or using source intensity modulation (e.g. in the manner of Manchester System implants) in order to assure dosimetric coverage of the specified margin (e.g. 2 mm) surrounding the tumor base.

  • Click the Calculate Sources button to calculate the source strengths required to fulfill the prescription conditions.

  • The sources in the plaque and their inventory entries will be updated to the strength required to deliver the prescription.

  • Note: to use (or perhaps, reuse) sources with a predetermined source strength on the date and time of plaque insertion you would instead click the Calc. Treatment Duration button to simply calculate the number of hours required to deliver the prescription using those sources. To prevent overriding the calibration of such sources (e.g. by accidentally clicking the calculate sources button) you should optionally lock the calibration such sources in the inventory editing sheet.

Step 11: Select an isodose legend for plotting isodose lines

Select the Isodose window from the PSWindows menu.


From the Legends menu choose MyFavorite.idos6.


Step 12: Calculate 2D planar and retinal dosimetry

Select the Planar Dosimetry window from the PSWindows menu.

  • From the Dosimetry menu select Calculate 2D Matrices. Some menu items are in red text as an alert that these critical components of a treatment plan are currently invalid or have never been calculated. The set of dose calculations that this function invokes are established in PS preferences. Usually the "2D Matrices" set would include at least the meridian and coronal planes, the inner scleral "aka retinal" surface (which is a 2D surface) and one or more dose histograms.
  • Isodose lines will appear in the Planar Dosimetry and Retinal Diagram windows.

To see both the meridian and coronal planes simultaneously set the window layout to multipane side-by-side using the controls in the toolbar.


Step 13: Calculate dose histograms

Select the Histogram window from the PSWindows menu.

  • From the Dosimetry menu choose Calculate Histogram #1 (RDAH). This will calculate the Retina Dose Area Histogram. If the text is red, the histogram is currently not valid or has never been calculated.
  • In the RDAH observe that coverage of both the tumor base (brown line) and tumor plus margin (green line) is >= 85 Gy.
  • From the Dosimetry menu choose Calculate Histogram #2 (DVH). This will calculate a Dose Volume Histogram. If the text is red, the histogram is currently not valid or has never been calculated.
  • In the DVH observe that coverage of the tumor volume (brown line) is >= 85 Gy.

Step 14: Print the plan
  • You can print documents individually, or as a group, to either paper or a .pdf file.

  • Printing as a group is more convenient.

  • Electronically distributing a plan by printing to a .pdf file is the fastest and most economical way for team review. The raw .pdf files that PS creates can be very large (often > 100 MB) and require file compression and optional encryption before being distributable as email attachments (attachments are usually limited to under 10 MB).

  • Eye Physics recommends using NXPowerLite Desktop software which we find will reduce the treatment plan .pdf file size to about 5 MB without noticeable loss of image quality. Instructions and an Applescript utility for AES256ISO encryption of the compressed .pdf files are provided in the PS6 installer package.

  • The documents to be included the printed group are indicated by the checkboxes below each document's icon in the Documents preview window toolbar.

There are several ways to print the document group. The recommended way is from the toolbar of the Documents preview window.

  1. The easiest way is to click the Print Group to PDF button which creates and saves a .pdf file directly to the current patient plan folder. PS uses an automated naming scheme for these files.
  2. Alternatively, you can click the Print Group control.
    PrintGroup which opens the MacOS Print window from which you can choose to print to paper or to a .pdf file with name and location of your choosing.

If you elect to use the MacOS Print window:

  • To print to paper click the Print button.

  • To print to a .pdf file (e.g. for paperless archiving or to email to a colleague) click the PDF popup menu.

  • From the popup menu select Save as PDF. MacOS will present a file saving window from which you can customize the file name and destination.

These are some example pages from a typical document group


Step 15: Save the plan

    From the File menu select Save Basic as...

  • In the MacOS Save window navigate to the desired storage location for this patient and click the Save button.

  • IMPORTANT: Typically, you should create and name a new folder for each patient somewhere in your Plaque Simulator Patients folder before beginning any planning operations and organize all files (e.g. images, plans, reports, pdfs) related to that patient in that folder.


Step 16: QA review

How to interpret the Prescription window.

  • In the toolbar
    • This prescription is for plaque #1.
    • The dose calculation is set for anisotropic linear sources.
    • T(r,d,μ) correction for attenuation in the COMS silicone seed carrier is enabled.
    • Scatter and flourescence modifiers attributable to the gold backing are disabled (because they are already included in the T(r,d,μ) silicone carrier modifier).
    • Calculation of collimation by the shell's lip is enabled.
    • Correction for reduced scatter (compared to water) owing to air in front of the eye is disabled.
  • In the prescription bar
    • The Rx dose is 85 Gy (text field).
    • The Rx point (a menu selection) is to the apex of tumor #1 which is 6 mm tall.
  • In the date control groups
    • The plaque insertion date is Wednesday March 10th, 2021 at 10 AM.
    • The implant duration is 168 hours.
    • The plaque removal date is Wednesday March 17th, 2014 at 11 AM.
    • IMPORTANT: The plaque removal time is 11 AM (instead of 10 AM) because of the local clock change that occurred as a result of daylight saving time beginning during the implant!
  • In the plaque Central AXis (CAX) table
    • The dose at 7 mm in the CAX table is 85 Gy. Note: in this plan, the plaque is centered directly below the tumor apex, so the plaque CAX passes through the tumor apex. The Rx point, in this case being at at the tumor apex, 6 mm from the inner sclera, is therefore 7 mm from the face (concave surface) of the plaque owing to an assumed scleral thickness of 1 mm.
    • The dose at the Rx point is 85 Gy with an average dose rate of 50.6 cGy/hour.
    • The dose at the tumor apex is also 85 Gy.
    • The Rx has been satisfied because the Rx point background tinting is green (if the Rx has not been satisfied the background tinting could be yellow or red).
    • The implant duration of 168 hours is within acceptable limits (a preference setting) because the time background tinting is green. If the implant duration were too short or too long, the time background tinting would be yellow.
  • In the footer controls
    • The Rx units (a menu selection) are set to Gy.

Plaque Simulator's QA point is located on the plaque CAX, 6 mm from the concave face of the plaque (in this case, the QA point happens to be 1 mm below the tumor apex).

In the QA Check document, the QA_Point dose in the green tinted section at the base of the table is calculated in the same manner as the Rx point, and indeed matches the Prescription window CAX table dose at 6 mm in the figure above. The QA_Check dose in the green tinted section at the base of the table is calculated as an isotropic point source in water according to the formula shown in the table. All of the information needed to reproduce the QA_Check calculation is tabulated in the document.

The isotropic point source in water QA_Check calculation will inevitably be greater than the QA_Point calculation which is based on anisotropic liner sources and includes various scatter and attenuation modifiers. For COMS plaques with silicone seed carriers, the difference may be as much as 15%.