History: The USC Plaques

Eye Physics (EP) plaques are much refined descendants of the plaque designs that were found to be the most useful at the University of Southern California (USC) from 1980 to 2010.

The first USC plaques were originally prototyped for Ir-192 seeds in the early to mid 1980s by LAC/USC physicist David Neblett (who in 1988 created the ROCS treatment planning program for the PC) and jeweler Jerry Schuber of nearby Commerce CA. The primitive seed positioning slots enabled the Ir-192 seeds to be mounted in reproducible loading patterns. These early Ir-192 plaques were retired in the late 1980s in favor of more refined second generation prototypes intended for I-125 seeds. Jerry sadly passed away of ALS disease in 2014.

In the late 1980s USC physicist Melvin Astrahan began development of the Plaque Simulator (PS) treatment planning software, worked with Jerry Schuber to revise the earlier USC Ir-192 plaque designs for I-125 seeds, prototyped many new plaque designs with much deeper seed positioning slots intended to also individually collimate the low energy radiation emitted by I-125 seeds, and eventually developed for PS the technology to prototype plaques using stereolithographic 3D printing. All EP plaques are compatible with seeds containing low energy radionuclides other than I-125 (e.g. Pd-103) so long as they conform to the now standardized cylindrical dimensions 0.8 x 4.5 mm.


1st Generation Ir-192 Plaques: (circa 1985).

Eye Physics Plaques

Many of the items in this menu and its submenus are disabled (dimmed) because they are no longer in production (e.g. they may be obsolete) or they are new designs intended for stereolithographic 3D printing and are not yet available as gold castings for clinical use. All Eye Physics plaques that are currently in production and/or available for rental from IsoAid may be accessed from the Plaque Files and Rental Plaques menus. To access a disabled model simply option-click the menu item.

EP Plaques

These are some of the 3rd Generation I-125 Plaques in development: (All 3rd gen. plaques are designed using PS6 and prototyped on our FormLabs 3D stereolithographic printer for direct to gold casting)

These models (most are size 24 or 25 spherical, some are oblate) are in production: (Note: some new models and sizes are not yet listed here because the number of available units may be fewer than 8. The latest models are included in PS6 software updates as .iplq6 files. Please check with IsoAid for availability of new models before ordering a plaque not listed here.)

2nd Generation I-125 Plaques: (manually prototyped)

Click one of the links below for the complete illustrated catalog of:

2nd Generation Plaques
(manually prototyped)

3rd Generation Plaques
(3D printed)

Whenever you see 3D models such as these examples:
Click and drag 3D models to rotate
Mouse scroll wheel to zoom
Right mouse button to pan

Seed coordinates and other information

When seed coordinates are displayed, the origin of the plaque coordinate system is shifted to the center of the concave surface of the plaque. The X axis of this coordinate system is the Central AXis (CAX) of the plaque. In the Plaque window you are looking at a 2D projection of the plaque onto the YZ plane.

You can often click pictures with coordinates to see an enlarged view with easier to read text.

If you need seed coordinates for a spreadsheet or some other application they can also be found in the .iqa6 (xml) files that are created for the PSQACheck application.

The physical dimensions of a plaque are only a rough estimator of the dosimetric coverage a plaque delivers to the base of a tumor. Dosimetric coverage is significantly influenced by the Rx altitude, seed angular orientation and optional intensity modulation of the radionuclide seed strengths in the plaque. Coverage can be several mm smaller or larger than the physical dimaensions of the plaque itself.


PS6 includes .iplq6 files with embedded pictures of the face of all Eye Physics plaques.