Dose Histogram Window

Plaque Simulator provides 2 dose histogram structures. Each histogram structure supports 2 plots and an independent calculation for each plaque. You can click the cursor anywhere on the plot to interactively display the dose and area (or volume) at that location. Note: Dose histograms in printed documents will be plotted in the same manner as the histograms in this window except that the plot rectangles will be automatically adjusted fit to the paper size and orientation.

By default:

  • Histogram #1 is a dose-area histogram of the retinal surface. Use the Retina-Dose-Area Histogram (RDAH) to confirm dosimetric coverage (e.g. 85 Gy) of the tumor base (GTV) and tumor base + margin (PTV), and to optimize seed loading patterns to reduce dose to critical retinal regions such as the macula, fovea and optic disc.
    • Plot #1 is a cumulative histogram.
    • Plot #2 is a differential histogram.
  • Histogram #2 is a dose-volume histogram of the eye, tumor and lens volumes. Use the Dose-Volume Histogram (DVH) to verify dosimetric coverage of the entire tumor volume.
    • Plot #1 is a cumulative histogram.
    • Plot #2 is a differential histogram.

Reference: Astrahan, M.A., The retina dose-area histogram: a metric for quantitatively comparing rival eye plaque treatment options, J Contemp Brachytherapy, 5(1): 23-32, 2013. Download PDF

The RDAH is usually the more useful metric in regard to treatment optimization because the critical regions of the eye that we are interested in sparing are primarily located in the retinal and choroidal layers which are better (and more rapidly) modeled by a surface area calculation of the inner sclera compared to a volumetric calculation of the entire eye.

From the File menu on the menubar you can export the currently selected histogram # for the selected plaque and mode as a tab separated values (.tsv) text file. This menu item will enable when valid histogram data has been calculated and is available for export.


You can customize your histogram plots to directly compare alternative plaque models and loading patterns by opting to overlay rivals. The examples below illustrate a comparison of the coverage of an EP1821 vs a COMS16 plaque for the same tumor and Rx using both cumulative and differential histograms. The diameter of the concave face of the EP1821 and COMS16 are nearly identical. Rx dose (85 Gy) coverage of the tumor base-margin surface (green curves in the RDAH plots) and tumor volume (brown curves in the DVH plots) are nearly identical. These histograms also reveal that maximum dose to the inner-scleral surface and optic disc surface (magenta curves) are significantly reduced for the EP1821 compared to the COMS16.





You can create mixed DVH, RDAH, cumulative and differential plots, customize the plotted range, line styles and so on in this window or via advanced settings found in the histogram document preferences pane.

Most of the time, you wiil want to use the axes parameters sheet "wizard" which you can access by clicking the Axes... buton at the bottom of the window or by double-clicking the x or y axes lines. This will open the axes parameters sheet primed for the most likely subsequent actions.

For finer customization you can access the histogram document preferences by double clicking anywhere else in the histogram window or by clicking the Preferences button at the bottom of the window. Changes in window settings are not automatically propagated to preferences, but there is a button in the preferences pane to do so. Changes to preferences, on the other hand, are automatically propagated to histogram window settings. Histogram window settings are saved in the .iplan6 patient file.