Basic Guidelines for the use of Eye Physics Technologies

Guidelines for the Eye Physics procedure in general:

  1. The accuracy of treatment planning using the Eye Physics Plaque Simulator software depends upon the quality of the CT, ultrasound and fundus images provided to the planner, and the training and experience of the planner.
  2. The better the image quality and the greater the experience of the planner in regard to interpreting the images, the more accurate will be the overall results.
  3. Eye Physics offers numerous training examples and tutorials on the eye physics web site and also provides individual consultation and training both via the internet or on-site upon request...
  4. CT (or MR) images covering the orbits at ≤ 1 mm slice spacing should be provided in DICOM format for multiplanar (MPR) and spheroidal surface reconstructions of the eye and tumor. 3D reconstructions within Plaque Simulator itself require installation of the DICOM toolkit DCMTK. Eye Physics also recommends using Osirix to manage DICOM access.
  5. Ultrasound images of the tumor provide the best measure of tumor height.
  6. A wide angle fundus image (e.g. Optos SLO), or a collage of fundus images, including the optic disc, the fovea, and as much of the tumor as can be photographed provide a good map of the shape and location of the tumor base. For tumors that are located too anteriorly to be entirely mapped via optical imaging, PS provides spheroidal surface reconstruction of the inner sclera from 3DCT
  7. Each institution is expected to provide its surgeons whatever tools they deem necessary for the surgical placement of eye plaques. Eye Physics recommends at minimum obtaining an indirect ophthalmoscope, a toric meridian angle marker and a Castroviejo caliper to mark suture coordinates on the eye.

Guidelines for DIY Plaque Simulators dosimetry planning:

  1. The institution is responsible to provide a computer capable of running MacOS 10.11 or later (Eye Physics recommends MacOS 11,12,13 etc... running on a desktop or laptop with >= 32GB RAM and >= 1TB SSD with an Apple Silicon M series cpu). Occasionally a flatbed scanner is useful if images will be provided as film or printed formats. Recommended 3rd party software products include Adobe Photoshop to crop and enhance ophthalmology images, the DICOM Toolkit DCMTK, and the OsiriX DICOM viewer and manager to integrate with your PACS.
  2. A typical prescription and dose rate for choroidal melanoma is 85 Gy delivered over 4 to 7 days but this is ultimately a choice of the local physicians.
  3. Select a plaque and radionuclide source loading pattern that encloses the tumor apex and at least a 2 mm retinal margin surrounding the tumor base within the prescribed (e.g. 85 Gy) isodose surface.
  4. Try to reduce dose to the macula, fovea and optic disc without compromising tumor coverage. This is achieved by experimenting with variations of radionuclide source location, orientation, radiation strength and plaque design.
  5. About 30 models of Eye Physics 3D printed plaques, as well as the older COMS designs, are available to rent through IsoAid. To rent a preloaded, pre-sterilized, with customizable seed strengths (e.g. intensity modulated seed loading), ready to implant plaque, print the treatment plan as a .pdf file and email it to your IsoAid representative at least 1 week before you need delivery. The rental plaque will arrive, ready to implant, with return shipping instructions and documents.
  6. Eye Physics also provides remote treatement planning and consultation services (ie via internet), billable through IsoAid as a component of the plaque rental service.

Guidelines for Eye Physics surgical positioning:

  1. The accuracy of the calculated suture coordinates depends on the quality of the CT, ultrasound and fundus images provided and the training and experience of the planner.
  2. Plaque Simulator calculated suture coordinates for the plaque are usually quite accurate but should be considered only as a guide to plaque placement.
  3. The surgeon should use a toric meridian angle marker and a Castroviejo caliper to mark the suture coordinates on the eye.
  4. The surgeon MUST ALWAYS visually confirm the placement using a dummy plaque and indirect ophthalmoscopic observation and/or ultrasound bscan or similar imaging technology. If the fit isn't as planned, the surgeon MUST manually adjust the placement coordinates to achieve the plan objectives...
  5. Most Eye Physics plaques are protyped using 3D printing and are cast from 18K gold alloy similar to the alloys used for jewelery and dental implants. Radionuclide seeds are glued into slots in the plaque face using a heat tolerant, medical instrument approved cyanoacylate adhesive. These slots both position the seeds at known coordinates and orientations with respect to the suture eyelets and collimate the radiation emitted from each seed into an intensity modulatable "fan" beam. This design enables the delivery conformal isodose treatment within the eye.
  6. Should a preloaded, presterilized Eye Physics plaque (or dummy plaque) lose its sterility due to accidental mishandling prior to or during surgery, it may be possible to resterilize on-site one time using a 4 to 10 minute flash cycle. Warning: repeated heat sterilization of a plaque containing radionuclide seeds should be avoided because it will eventually weaken the adhesion of the seeds to the gold shell due to thermal expansion and subsequent contraction of the gold shell as it heats and cools.
  7. Return rented plaques to IsoAid as soon as possible following removal from the patient. Return instructions, including sterilzation procedures, are included with the return shipping documents...