A technique for accurate placement of episcleral iodine-125 plaques

A Novel Method for Transillumination

PURPOSE

To introduce a cost-efficient device for transillumination in the management of uveal melanoma.

METHODS

Todorich Illuminated Depressor is a ball-point depressor, designed to work with the 23-, 25- and 27-gauge Alcon Constellation endoillumination. It was invented to allow indentation and peripheral vitreous visualization for vitrectomy.

RESULTS

Todorich depressor combined with endoillumination can also work as a device for transillumination for tumor localization. We started using this method of transillumination for the management of uveal melanomas since September 2020 and have successfully performed Ru-106 plaque brachytherapy for 10 cases of uveal melanoma. Three were large choroidal melanoma cases, and en bloc tumor resection by partial lamellar sclerouvectomy was successfully performed after precise localization of tumors using this method.

CONCLUSION

Alcon Constellation endoillumination capped with Todorich Illuminated Depressor is an affordable and viable alternative for transillumination of intraocular tumors.

Cherenkov Luminescence Imaging for Assessment of Radioactive Plaque Position in Brachytherapy of Uveal Melanoma: An In Vivo Feasibility Study

Purpose

To study the feasibility of using Cherenkov luminescence imaging (CLI) to evaluate and document ruthenium-106 plaque position during brachytherapy of uveal melanoma.

Methods

Ruthenium-106 decays by emitting high-energy beta particles. When the electrons pass through the eye, Cherenkov radiation generates a faint light that can be captured by highly sensitive cameras. Patients undergoing ruthenium-106 plaque brachytherapy for posteriorly located choroidal melanoma were examined by CLI, which was performed in complete darkness with an electron multiplying charged-coupled device camera mounted on a fundus camera modified for long exposures.

Results

Ten patients with tumors ranging from 5.8 to 13.0 mm in largest basal diameter and 2.0 to 4.6 mm in height were included. The plaques had an activity between 0.035 and 0.089 MBq/mm² at the time of examination (1–4 days after implantation). CLI revealed the actual plaque position by displaying a circular area of light in the fundus corresponding with the plaque area. The Cherenkov light surrounded the tumor as a halo, which showed some asymmetry when the plaque was slightly displaced. The light intensity correlated positively with plaque activity and negatively with tumor pigmentation. Exposure times between 30 and 60 seconds were required to display the plaque position and delineate the tumor area. The long exposures made it difficult to maintain stable eye fixation and optimal image quality.

Conclusions

CLI is a novel method to assess and document ruthenium-106 plaque position in brachytherapy for uveal melanoma.

Translational Relevance

Ocular CLI may provide relevant radiation data during and after implantation of radioactive plaques, thus improving the accuracy of episcleral brachytherapy.

A Modified Dummy Plaque for the Accurate Placement of Ruthenium-106 Plaques in Brachytherapy of Intraocular Tumours

PURPOSE

To present a new technique to ensure the correct positioning of ruthenium plaques in episcleral brachytherapy.

MATERIALS AND METHODS

An acrylic dummy plaque is made opaque by sanding both sides with sandpaper, and its edge is covered by a black marking tape. This modified plaque is temporarily sutured to the sclera overlying the choroidal tumour site. The tip of an endoillumination probe is placed at the anterior edge of the plaque, yielding a strong light scattering within the opaque acrylic material. Due to the light-absorbing tape around the plaque border, the scattered light is confined within the plaque, and its perimeter can be observed by indirect ophthalmoscopy as a circle of transilluminated light surrounding the tumour. When the correct position has been found, the dummy plaque is replaced by a ruthenium-106 plaque.

RESULTS

The technique was successfully applied in 5 patients with posterior choroidal melanoma. Compared to standard focal transillumination, its main advantage is that the position of the entire plaque and tumour can be observed simultaneously in one field without any movement or manipulation of the light probe or plaque.

CONCLUSION

The described transillumination technique and modified dummy plaque facilitate the correct positioning of ruthenium plaques in brachytherapy of choroidal melanoma.

Evaluation of the surgical learning curve for I-125 episcleral plaque placement for the treatment of posterior uveal melanoma: a two decade review

Purpose

To evaluate the surgical learning curve in episceral plaque brachytherapy placement in the management of posterior uveal melanoma.

Methods

A retrospective chart review of two cohorts of 250 consecutive patients undergoing plaque placement for posterior uveal melanoma from 2002 to 2004 and from 2008 to 2009 was conducted. The plaque–tumor apposition rates verified by intraoperative echography were evaluated and correlated with surgical volume over a 19-year period.

Results

In an initial study of 29 consecutive patients undergoing plaque placement from January 1992 to January 1995, a suboptimal plaque placement rate of 21% (n = 29) was identified. This percentage declined to 12% (n = 100) from January 2002 to January 2004, and further declined to 4% (n = 150) from June 2008 to August 2009. The tumor–plaque apposition rates for these three groups were 79% (1992–1995), 88% (2002–2004), and 96% (2008–2009). An estimated surgical volume of 1275 cases was performed to achieve a >90% precision rate for first application of primary plaque centration.

Conclusion

There are challenges to mastering the precise placement of radioactive plaques for posterior uveal melanoma. We have demonstrated a significant learning curve for plaque placement techniques, and have emphasized the importance of intraoperative ultrasound in the verification of plaque placement, thus allowing for intraoperative repositioning.

The American Brachytherapy Society recommendations for brachytherapy of uveal melanomas

PURPOSE

This article presents the American Brachytherapy Society (ABS) guidelines for the use of brachytherapy for patients with choroidal melanomas.

METHODS

Members of the ABS with expertise in choroidal melanoma formulated brachytherapy guidelines based upon their clinical experience and a review of the literature. The Board of Directors of the ABS approved the final report.

RESULTS

Episcleral plaque brachytherapy is a complex procedure and should only be undertaken in specialized medical centers with expertise in this sophisticated treatment program. Recommendations were made for patient selection, techniques, dose rates, and dosages. Most patients with very small uveal melanomas (<2.5 mm height and <10 mm in largest basal dimension) should be observed for tumor growth before treatment. Patients with a clinical diagnosis of medium-sized choroidal melanoma (between 2.5 and 10 mm in height and <16 mm basal diameter) are candidates for episcleral plaques if the patient is otherwise healthy and without metastatic disease. A histopathologic verification is not required. Small melanomas may be candidates if there is documented growth; some patients with large melanomas (>10 mm height or >16 mm basal diameter) may also be candidates. Patients with large tumors or with tumors at peripapillary and macular locations have a poorer visual outcome and lower local control that must be taken into account in the patient decision-making process. Patients with gross extrascleral extension, ring melanoma, and tumor involvement of more than half of the ciliary body are not suitable for plaque therapy. For plaque fabrication, the ophthalmologist must provide the tumor size (including basal diameters and tumor height) and a detailed fundus diagram. The ABS recommends a minimum tumor (125)I dose of 85 Gy at a dose rate of 0.60-1.05 Gy/h using AAPM TG-43 formalism for the calculation of dose. NRC or state licensing guidelines regarding procedures for handling of radioisotopes must be followed.

CONCLUSIONS

Brachytherapy represents an effective means of treating patients with choroidal melanomas. Guidelines are established for the use of brachytherapy in the treatment of choroidal melanomas. Practitioners and cooperative groups are encouraged to use these guidelines to formulate their treatment and dose reporting policies. These guidelines will be modified as further clinical results become available.

Transillumination for accurate placement of radioactive plaques in brachytherapy of choroidal melanoma

PURPOSE

To present a technique for accurate plaque placement in episcleral brachytherapy of choroidal melanoma.

METHODS

The tumor margins are marked on the scleral surface, and a dummy plaque is temporarily sutured to the globe. A fiber optic light pipe is then wedged into the space between the sclera and the plaque. Because of the reflecting inner surface of the plaque, the perimeter of the plaque can easily be observed during indirect ophthalmoscopy as a circle of light surrounding the tumor. By this method, it is possible to determine the exact position of the entire plaque in relation to the tumor and make the necessary adjustments. When the correct position is found, the dummy plaque is replaced by a radioactive plaque.

RESULTS

Since 1993, we have routinely used this procedure in episcleral brachytherapy.

CONCLUSION

This modified transillumination technique facilitates a correct positioning of episcleral plaques.

Intraoperative echographic localization of iodine-125 episcleral plaque for brachytherapy of choroidal melanoma

PURPOSE

To report intraoperative echographic localization of iodine-125 episcleral plaque for brachytherapy of choroidal melanoma.

METHODS

In a retrospective study, 117 eyes with medium-sized choroidal melanoma in 117 patients not participating in the Collaborative Ocular Melanoma Study underwent iodine-125 episcleral plaque radiotherapy with intraoperative echographic verification of plaque placement between January 1992 and December 1998 at the Bascom Palmer Eye Institute.

RESULTS

After initial plaque placement using standard localization techniques, intraoperative echography demonstrated satisfactory tumor-plaque apposition in 76% of eyes (89 of 117). In the 28 eyes (28 of 117, 24%) that required repositioning of the plaque, the extent of misplacement was less than 1 mm in 10 eyes, 1.1 to 3.0 mm in six eyes, and greater than 3 mm in eight eyes. Two eyes had tilting of the plaque, and in two additional eyes, although the plaque covered all tumor margins, the centration was considered suboptimal. Repositioning was necessary in 1 eye with an anteriorly located tumor (1 of 13, 7.7%) and in 20 eyes with peripapillary or posterior pole tumors (20 of 67, 26.3%). Anteriorly located tumors required plaque repositioning significantly less frequently than did posteriorly located tumors (P = .041). Misalignment involved one tumor margin in 23 eyes and two margins in five eyes. The most commonly misaligned margins were the lateral (35%) and posterior margins (26%). In no case was an anterior marginal misalignment documented. At a mean follow-up of 37 months, no tumor-related death or metastatic disease was noted. Two of the 117 patients (1.7%) had local tumor recurrence and underwent enucleation.

CONCLUSIONS

Intraoperative echography is an effective adjunct for localization and confirmation of tumor-plaque relationship. This technique facilitates the identification and correction of suboptimal plaque placement at the time of surgery, potentially minimizing treatment failures.

Diode-light transillumination for ophthalmic plaque localization around juxtapapillary choroidal melanomas

PURPOSE

An evaluation of plaque-mounted diode-light transillumination (DLT) for localization of episcleral plaques beneath juxtapapillary tumors.

METHODS AND MATERIALS

Two patients scheduled for radiotherapy for juxtapapillary melanomas were offered DLT as an additional method of ophthalmic plaque localization. Plaques were constructed by affixing 4 non-heat producing, light-emitting diodes with their apertures flush with the episcleral outer surface of the plaque's rim. Bio-implantable epoxy was used to encapsulate the electronic components. Then the plaques were loaded with 103Pd seeds. After the eye-plaques were sewn to the episclera covering the base of the intraocular tumors; the diode-lights were illuminated, viewed and recorded. Photodocumentation of the relative position of the 4 lights around tumor's base was obtained in both cases.

RESULTS

Digital images of plaque-mounted diode retro-transillumination were obtained. No evidence of diode-light toxicity was noted. Both tumors were found to be covered by the ophthalmic plaques.

CONCLUSION

Juxtapapillary tumors are often difficult or impossible to visualize with standard transillumination techniques and have been associated with poor local control rates. We have developed plaque-mounted DLT in an effort to improve ophthalmic plaque localization. Retrobulbar transillumination was viewed by indirect ophthalmoscopy and recorded with video-imaging. This technique provides unique photographic documentation of episcleral plaque localization beneath juxtapapillary tumors.

A technique for suturing peripapillary radioactive plaques

PURPOSE

To describe a technique for suturing radioactive plaques positioned posteriorly and adjacent to the optic nerve.

METHODS

Posterior and juxtapapillary notched radioactive iodine-125 plaques were sutured using four 5/0 nylon sutures. Two sutures were placed in the sclera at the anterior border of the plaque position and passed through the eyelets at the anterior edge of the plaque. Two sutures were attached to the posterior eyelets and brought to either side of the optic nerve, under the rectus muscles, to be sutured to sclera anterior to the insertion of the recti muscles. The position of the plaques was documented intraoperatively using sterile B-scan ultrasonography.

RESULTS

Plaques positioned and sutured using this technique were found by ultrasonography to be tight up against the sclera and optic nerve.