Ru-106 Plaque Research Articles

Monte Carlo-based dosimetry of proposed bi-radionuclide (125I and 106Ru/106Rh) eye plaque: A feasibility study.

Combining the sharp dose fall off feature of beta-emitting 106Ru/106Rh radionuclide with larger penetration depth feature of photon-emitting125I radionuclide in a bi-radionuclide plaque, prescribed dose to the tumor apex can be delivered while maintaining the tumor dose uniformity and sparing the organs at risk. The potential advantages of bi-radionuclide plaque could be of interest in context of ocular brachytherapy. The aim of the study is to evaluate the dosimetric advantages of a proposed bi-radionuclide plaque for two different designs, consisting of indigenous 125I seeds and 106Ru/106Rh plaque, using Monte Carlo technique. The study also explores the influence of other commercial 125I seed models and presence or absence of silastic/acrylic seed carrier on the calculated dose distributions. The study further included the calculation of depth dose distributions for the bi-radionuclide eye plaque for which experimental data are available. The proposed bi-radionuclide plaque consists of a 1.2-mm-thick silver (Ag) spherical shell with radius of curvature of 12.5mm, 20µm-thick-106Ru/106Rh encapsulated between 0.2mm Ag disk, and a 0.1-mm-thick Ag window, and water-equivalent gel containing 12 symmetrically arranged 125I seeds. Two bi-radionuclide plaque models investigated in the present study are designated as Design I and Design II. In Design I, 125I seeds are placed on the top of the plaque, while in Design II 106Ru/106Rh source is positioned on the top of the plaque. In Monte Carlo calculations, the plaque is positioned in a spherical water phantom of 30cm diameter. The proposed bi-radionuclide eye plaque demonstrated superior dose distributions as compared to 125I or 106Ru plaque for tumor thicknesses ranges from 5 to 10mm. Amongst the designs, dose at a given voxel for Design I is higher as compared to the corresponding voxel dose for Design II. This difference is attributed to the higher degree of attenuation of 125I photons in Ag as compared to beta particles. Influence of different 125I seed models on the normalized lateral dose profiles of Design I (in the absence of carrier) is negligible and within 5% on the central axis depth dose distribution as compared to the corresponding values of the plaque that has indigenous 125I seeds. In the presence of a silastic/acrylic seed carrier, the normalized central axis dose distributions of Design I are smaller by 3%-12% as compared to the corresponding values in the absence of a seed carrier. For the published bi-radionuclide plaque model, good agreement is observed between the Monte Carlo-calculated and published measured depth dose distributions for clinically relevant depths. Regardless of the type of 125I seed model utilized and whether silastic/acrylic seed carrier is present or not, Design I bi-radionuclide plaque offers superior dose distributions in terms of tumor dose uniformity, rapid dose fall off and lesser dose to nearby critical organs at risk over the Design II plaque. This shows that Design I bi-radionuclide plaque could be a promising alternative to 125I plaque for treatment of tumor sizes in the range 5 to 10mm.

Local tumour control and patient survival after ruthenium-106 brachytherapy for small choroidal melanoma

AimTo report local tumour control, metastasis and survival rates of patients with small choroidal melanoma (CM) after treatment with ruthenium-106 (Ru-106) plaque brachytherapy.MethodsRetrospective case series of 353 consecutive eyes with...

Adjuvant Brachytherapy with Ruthenium-106 to Reduce the Risk of Recurrence of Conjunctival Melanoma after Excision

Introduction: Local recurrence of conjunctival melanoma (CM) is common after excision. Local radiotherapy is an effective adjuvant treatment option, and brachytherapy with ruthenium-106 (106Ru) is one such option. Thus, herein, we aimed to describe our experience with and the clinical results of post-excision adjuvant 106Ru plaque brachytherapy in patients with CM. Methods: Nineteen patients (8 men and 11 women) received adjuvant brachytherapy with a 106Ru plaque after tumor excision. The mean adjuvant dose administered was 109 Gy (range, 80–134 Gy), and a depth of only 2.2 mm was targeted because the tumor had been excised. A full ophthalmological examination including visual acuity testing, slit-lamp examination, and indirect ophthalmoscopy was performed before therapy and at every postoperative follow-up. The mean follow-up period was 62 months (range, 2–144 months). Results: Three patients developed a recurrence in a nontreated area, at either the conjunctiva bulbi or the conjunctiva tarsi. None of the patients developed a recurrence in the treated area. The local control rate was 84% (16/19). Conclusion: 106Ru plaque brachytherapy is an effective adjuvant treatment to minimize the risk of local recurrence after excision of a CM. Patients have to be followed up regularly and carefully for the early detection of recurrence.

Ruthenium-106 (106Ru) plaque brachytherapy for treatment of circumscribed choroidal hemangioma.

To describe the clinical and imaging features of circumscribed choroidal hemangiomas (CCH) and their treatment outcomes with Ruthenium-106 (106Ru) plaque brachytherapy. Retrospective study of 24 patients (24 eyes) diagnosed with CCH and treated with 106Ru plaque between 2017 and 2022. Analysis included pre- and post-treatment clinical and imaging features such as tumor regression, reduction in height, subretinal fluid (SRF) resolution, and change in best-corrected visual acuity (BCVA). The mean age at presentation was 36 years (range, 16-57). The most common tumor location was the temporal quadrant (n = 19) with macular involvement (n = 13). Associated features were macular SRF (n = 22) and inferior exudative retinal detachment (n = 10). Nineteen of the 24 patients underwent primary treatment, whereas 5 patients underwent plaque as a salvage treatment. The mean tumor apex dose was 40 Gy. At a median follow-up of 7.5 months (range 3-65 months), 18 eyes showed complete regression, whereas 6 eyes showed partial regression. The mean height decreased from 4.8 (SD 1.28) mm at presentation to 2.5 (SD 1.63) mm. Median BCVA improved from logMAR 1.2 (IQR 0.4-2) at baseline to logMAR 1.05 (IQR 0.1-1.95) (p = 0.4). Complete resolution of the macula and tumor SRF was observed in 15 (68%) and 13 (57%) eyes, respectively. The radiation-related complications observed were radiation maculopathy (4 eyes), retinopathy (1 eye), and vitreous hemorrhage (1 eye). Ruthenium-106 plaque brachytherapy is effective for CCH (> 3 mm height) as a primary and salvage treatment for tumors unresponsive to other modalities.

Investigation of the 106Ru ophthalmic plaque dose distribution in a pseudotumor-contained eye-equivalent phantom by silica glass beads

PurposeTo investigate the 106Ru dose distribution in an intraocular pseudotumor by micro silica glass beads thermo-luminescence dosimeters (TLD). Materials and methodsDosimetry was conducted using Monte Carlo (MC) simulation as well as an experimental setup by employing an in-house eye equivalent phantom. A BEBIG CCA model of 106Ru plaque was used. Bead TLDs were modeled using MCNPX code, choosing water and plexiglass as phantom mediums along with CCA plaque. The deposited energy and electron energy spectra were calculated using *f8 and f4 tallies, respectively. A dedicated eye-equivalent phantom was designed and fabricated by 3D-printing techniques to place glass beads. ResultsAbsorbed dose at the central axis of the CCA plaque by beads TLDs was compared to manufacturer-reported data and simulation results. Maximum, minimum, and mean relative differences of 23%, 7%, and 15% with the manufacturer and 14%, 0%, and 1.6% with the simulation were obtained, respectively. Replacing glass bead material with water resulted in an average relative difference of 33.9% in absorbed energy per mass unit, corresponding to 21% and 44.8% at the first (0.5 mm depth) and last dosimetry points (9.5 mm depth), respectively. It has also been shown that glass beads can shadow each other, leading to a dose reduction of 15%. ConclusionA specific eye equivalent phantom with a pseudotumor was constructed, and silica glass beads were used for dosimetry. The results of the experiment and the MC simulation are in good accord. In the case of 106Ru ophthalmic brachytherapy plaque dosimetry, replacing glass beads material with water led to a mean difference of about 34% as well as shadowing effects. This emphasizes how crucial it is to employ a reliable correction factor in clinical applications.

A Novel Method for Transillumination.

To introduce a cost-efficient device for transillumination in the management of uveal melanoma. Todorich Illuminated Depressor(TID) is a ball-point depressor, designed to work with the 23-, 25- and 27-gauge Alcon Constellation endoillumination. It is invented to allow indentation and peripheral vitreous visualization for vitrectomy. 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 enbloc tumor resection by partial lamellar sclerouvectomy were successfully performed after precise localization of tumors using this method. Alcon Constellation endoillumination capped with Todorich Illuminated Depressor, is an affordable and viable alternative for transillumination of intraocular tumors.

Surgical Treatment of a Large Choroidal Melanoma

Purpose: We report successful eyeball-preserving management of a patient with a large choroidal melanoma. We combined partial lamellar sclerouvectomy (PLSU) with ruthenium (Ru)-106 plaque brachytherapy.Case summary: A 48-year-old woman with a history of asthma visited our clinic with a chief complaint of gradual loss of vision at the nasal side of her right eye (best-corrected visual acuity 0.6). Fundus examination revealed a mushroom-shaped, dark choroidal mass 17.1 mm (basal diameter) × 14.2 mm (apical height). There was no evidence of distant metastasis. To remove the tumor while preserving the eyeball, we combined PLSU and simultaneous Ru-106 plaque brachytherapy with the patient under hypotensive general anesthesia. At 6 weeks postoperatively, trans pars plana vitrectomy with silicone oil injection was performed to remove the vitreous hemorrhage and treat the retinal detachment. Intravitreal bevacizumab (Avastin, Genentech Inc., San Francisco, CA, USA) (0.05 mL, 1.25 mg) was injected every 2 months to prevent the development of radiation retinopathy. No residual tumor, recurrence, or distant metastasis was noted during follow-up of 2 years. The patient was stable with no ocular complications at her last visit (2 years postoperatively).Conclusions: Contrary to what we expected and despite the surgical difficulties, PLSU combined with Ru-106 plaque brachytherapy is a useful eyeball-preserving strategy even when encountering a very large choroidal melanoma (diameter > 16 mm and apical height > 10 mm). Such a melanoma was previously believed to be treatable only via enucleation.

PHSOR02 Presentation Time: 12:35 PM: Practical Considerations for Dosimetric Verification of Ru-106 Eye Plaque Vendor Certificate Using Radiochromic Film

<h3>Purpose</h3> To develop a practical and efficient method for the dosimetric verification of Ru-106 plaques using radiochromic film measurements. <h3>Materials and Methods</h3> A hemispherical Solid Water^TM phantom with two quadrants was constructed with 12 mm radius to fit with eye plaque models - CCA, CCB, CCD and COB (Eckert & Ziegler BEBIG GmbH, Berlin, Germany). Each Ru-106 plaque was placed on the convex surface of the phantom for the film irradiations. Two types of radiochromic Gafchromic^TM dosimetry films (Ashland Advanced Materials, Bridgewater, NJ, USA) were studied - HD-V2 film with 12 μm active layer on a 97 μm clear polyester substrate and EBT-XD film with 25 μm active layer sandwiched between two 125 μm thick clear polyester substrates. A hemispherical film cut was sandwiched between the two quadrants of the phantom. Irradiation time for each plaque was calculated based on the dose rate from the vendor source certificate per AAPM TG 221 protocol. For each plaque, at least three irradiations were completed with each film type. AAPM TG 55 recommendations were used for film handling and scanning. Film dose measurements were analyzed at clinically relevant depth of 2 mm - 5 mm. For each film type, an optical density to dose calibration curve was obtained using a NIST calibrated Sr-90 source and a NIST-traceable 6 MV clinical linac beam. Measured film dose obtained using the calibration curve was corrected with MCNP derived Solid Water^TM to water dose conversion factors. Measured film absolute dose to water was compared with predicted dose to water value from the vendor source certificate for each eye plaque. Type A and B uncertainty components were reported. <h3>Results</h3> Using 6 MV calibration for HD-V2 film, the average percentage dose difference between film-measured vs. calculated dose per AAPM TG 221 from the vendor certificate at depth of 2 mm (6MV-Cal_HD-V2_DD%) for CCA, CCB, COB and CCD plaques were -9.2%, -6.3%, 0.9% and -7.7% respectfully. Similarly, Sr-90-Cal_HD-V2_DD% were -11.1%, -2.4%, 0.1% and -6.7% respectively. For EBT-XD, 2.5 mm measurements were taken instead of 2 mm, because of artifacts from the film cutting technique at shallower depth. Hence at 2.5 mm, 6MV-Cal_EBT-XD_DD% were -10.2%, -7.2%, -7.4% and -10.1% respectively; and Sr-90-Cal_EBT-XD_DD% were -5.5%, -3.0%, -3.1% and -6.1% respectively. All the DD% were within the uncertainty of the film measurements performed (13% at 2 mm - 5 mm depth, k = 2 with Sr-90 film calibration) and reported by the vendor (11% at 2 mm depth, k = 2). Results from the 6 MV vs. Sr-90 calibration curve were within 2% for HD-V2 film and within 5% for EBT-XD film. The average DD% between 2 mm-5 mm depths were within 15% for all plaques for both film types, using either 6 MV or Sr-90 calibration methods. DD% was smaller at shallow depths and increased slightly and gradually at the deeper depths. EBT-XD film was more prone to film damage due to polyester layer separation and provided more heterogenous DD% results for 2.5 mm-5 mm depths. EBT-XD film also had more variance between the two film calibration methods. <h3>Conclusions</h3> We have provided a simple and efficient method for dosimetric verification of Ru-106 eye plaque vendor certificate with radiochromic film measurements. Based on our experience, the HD-V2 film calibrated with 6 MV clinical linac beam provides the most practical solution for dosimetric verification of the data provided in the Ru-106 eye plaque vendor certificate.

Ruthenium-106 plaque radiotherapy for uveal melanoma: analysis of tumor dimension and location on anatomical and functional results

BackgroundTo report the long-term outcomes of Ru-106 plaque radiotherapy in eyes with uveal melanoma (UM) and to assess the effect of tumor thickness and location on final outcomes.MethodsMedical records of 234 patients undergoing Ru-106 plaque radiotherapy for UM were reviewed, and the visual outcome, globe preservation, and patient survival were evaluated. The results of 2 groups were compared: 1. between thin (small and medium-sized, thickness < 7 mm, 148 eyes [63.2%]) and thick (thickness ≥ 7 mm, 86 eyes [36.8%]) tumors, and 2. between large (largest basal diameter [LBD] > 12 mm, 109 eyes [46.6%]) and medium/small (LBD ≤ 12 mm, 125 eyes [53.4%]). In addition, a comparison of the juxtapapillary location in 46 eyes (19.7%) versus tumors arising elsewhere and between tumors with and without ciliary involvement in 48 eyes (21.5%) were done.ResultsThe patients were followed for a median of 54.2 months (range: 6–194.5 months). After adjusting for baseline visual acuity (VA), there was no significant association between final VA and different dimension and tumor location groups. Final globe preservation was 91.9%, and there was no significant difference between different dimension- and ciliary body involvement groups regarding anatomical success rate. The juxtapapillary tumors had lower globe preservation (80.4% vs .94.7%, p = 0.002). The hazard ratio (HR) for enucleation in juxtapapillary tumors was HR = 6.58 (95-CI: 3.84 to 11.21). The overall metastasis rate was 6.8%, with no significant difference in juxtapapillary tumors (4.3% vs.7.4%, p = 0.455).ConclusionsRu-106 plaque radiotherapy is an effective treatment for thick and large UM. With this type of treatment, the globe preservation rate is lower in juxtapapillary tumors, but there is no significant difference in the metastasis rate.

Monte Carlo simulation of tilted contact plaque brachytherapy placement for juxtapapillary retinoblastoma

BackgroundThe 106-Ruthenium contact plaque applicator is utilized for the treatment of intraocular tumor within a thickness of less than 6 mm. If anything obstructs the placement of the plaque applicator, the treatment is generally difficult because the applicator has to be temporarily located just on the opposite side of the retinal tumor. Furthermore, the plaque applicator edge of approximately 1 mm does not contain 106Ru, estimating the delivered radiation dose for eccentric tumor is challenging because the lateral dose profile is inadequately provided by the manufacture’s certification. This study aims to simulate tumor coverage of the tilted applicator placement for treating an infant with juxtapapillary retinoblastoma and to achieve the effective treatment.Case presentationWe present an infant with retinoblastoma whose tumor involved macular and was invading just temporal side of the optic disc. Additionally, posterior staphyloma was induced by a series of previous treatments, making it more difficult to treat the standard plaque placement. Thus, the applicator type of CCA was intentionally tilted to the eyeball and the distance between the posterior edge of the applicator and the eyeball had to be then equal to or more than 2 mm based on the dose distribution of the applicator calculated using Monte Carlo simulation to minimize damage to surrounding tissues while covering the tumor. It was then comparable to the certification and previous reports. Based on the acquired dose distribution, the optimal placement of the applicator was derived from varying the distance between the applicator’s edge and the eyeball, and the distance was then determined to be 2 mm. In this case, the minimum dose rate in the tumor was 25.5 mGy/min, and the time required to deliver the prescribed dose was 26.2 h. Therefore, the tilted 106Ru plaque applicator placement could deliver the required dose for the treatment. The physical examination revealed no active tumor as a result of the treatment.ConclusionsOptimizing the placement of the 106Ru plaque applicator, it was possible to guarantee that the prescribed dose will be delivered to the tumor even if the standard placement is not possible for the juxtapapillary tumor.

Long-Term Outcomes in Uveal Melanoma After Ruthenium-106 Brachytherapy.

Uveal melanoma is the most common primary intraocular malignancy. The aim of this retrospective study was to report the results after ruthenium-106 (Ru-106) plaque brachytherapy for uveal melanoma in terms of tumor control, visual acuity, radiation-related complications, tumor recurrence, metastases, and patients’ survival rate during 4 years’ follow-up. A total of 355 eyes from 355 patients have been treated with Ru-106 plaque brachytherapy for uveal melanoma between February 2011 and March 2020. Five patients were lost to follow-up, and then 350 eyes of 350 patients (mean age 58 ± 11 years) were enrolled in this retrospective study. All patients underwent a complete ophthalmic examination including echography and spectral domain–optical coherence tomography. The mean follow-up was 4 years (3 months to 9 years). After treatment, the mean tumor thickness was reduced to 1.75 ± 0.21 mm. Radiation complications were found in 63% of patients: 38% showed radiation maculopathy, 11% had optic neuropathy, and 14% developed cataracts. Cancer-free survival was 99%, 97%, and 85%, respectively, at 5, 7, and 9 years. Ru-106 plaque brachytherapy represents a reliable treatment of uveal melanoma. This technique is valid and safe with a low rate of ocular complications during a long-term follow-up.

Histopathology-guided management of ocular surface squamous neoplasia with corneal stromal or scleral invasion using ruthenium-106 plaque brachytherapy

Background/aimTo evaluate the safety and efficacy of ruthenium-106 (Ru-106) plaque brachytherapy in managing invasive ocular surface squamous neoplasia (OSSN).MethodsThis is a retrospective, non-comparative, interventional case series of 42 eyes with...

Evaluation of radiation maculopathy after treatment of choroidal melanoma with ruthenium-106 using optical coherence tomography angiography

BackgroundTo assess the impact of brachytherapy on macular microvasculature utilizing optical coherence tomography angiography (OCTA) in treated choroidal melanoma.MethodsIn this retrospective observational case series, we reviewed the recorded data of the patients with unilateral extramacular choroidal melanoma treated with ruthenium − 106 (106Ru) plaque radiotherapy with a follow-up period of more than 6 months. Automatically measured OCTA retinal parameters were analysed after image processing.ResultsThirty-one eyes of 31 patients with the mean age of 51.1 years were recruited. Six eyes had no radiation maculopathy (RM). From 25 eyes with RM, nine eyes (36%) revealed a burnout macular microvasculature with imperceptible vascular details. Twenty-one non-irradiated fellow eyes from the enrolled patients were considered as the control group. Foveal and optic disc radiation dose had the highest value to predict the burnout pattern (ROC, AUC: 0.763, 0.727). Superficial and deep foveal avascular zone (FAZ) were larger in irradiated eyes in comparison to non-irradiated fellow eyes (1629 μm2 vs. 428 μm2, P = 0.005; 1837 μm2 vs 268 μm2, P = 0.021; respectively). Foveal and parafoveal vascular area density (VAD) and vascular skeleton density (VSD) in both superficial and deep capillary plexus (SCP and DCP) were decreased in all irradiated eyes in comparison with non-irradiated fellow eyes (P < 0.001). Compared with non-irradiated fellow eyes, irradiated eyes without RM had significantly lower VAD and VSD at foveal and parafoveal DCP (all P < 0.02). However, these differences at SCP were not statistically significant.ConclusionThe OCTA is a valuable tool for evaluating RM. Initial subclinical microvascular insult after 106Ru brachytherapy is more likely to occur in DCP. The deep FAZ area was identified as a more critical biomarker of BCVA than superficial FAZ in these patients.

On measuring the 3D dose distribution for notched and circular Ru-106 plaque shapes through Gafchromic film dosimetry approach

Ruthenium-106 (106Ru) plaques are specific applicators dedicated for intraocular brachytherapy. Small tumor volume and presence of vital organs in its close vicinity as well as appearance of very high dose gradient regions around the employed plaques cause unique challenges in plaque-based brachytherapy. Therefore, access to 3D dose distribution for each brachytherapy plaque is quite helpful to decide about tumor volume coverage and overexposure of surrounding sensitive organs. Current study aims to measure the 3D dose distribution for two commercially available 106Ru plaques using film dosimetry.COB (a notched-shape plaque) and CGD (a fully circular plaque) 106Ru plaques were used and dose distributions in different planes were measured by simultaneously employing a 3D printed eyeball phantom and Gafchromic EBT3 films. Finally, 3D dose distributions were acquired by interpolating the measured 2D dose data at different planes.The results showed that employing the COB plaque tilts the isodose curves toward the non-notched edge of the plaque, while no isodose tilting was observed for CGD plaque. The obtained 3D dose distributions were different for studied plaques. Non-uniform 3D dose distributions were found for both plaques which can be attributed to the plaque design and reference point position on plaque central axis.Finally, it can be concluded that the obtained 3D dose distributions can specify the optimal tumor shape which can be adequately covered by brachytherapy plaque with minimizing the dose non-uniformity and hot point formation inside the treated volume. Obtained 3D dose distribution for each plaque can be employed for patient treatment planning.

A Monte Carlo dose calculation system for ophthalmic brachytherapy based on a realistic eye model.

There is a growing trend towards the adoption of model-based calculation algorithms (MBDCAs) for brachytherapy dose calculations which can properly handle media and source/applicator heterogeneities. However, most of dose calculations in ocular plaque therapy are based on homogeneous water media and standard in-silico ocular phantoms, ignoring non-water equivalency of the anatomic tissues and heterogeneities in applicators and patient anatomy. In this work, we introduce EyeMC, a Monte Carlo (MC) model-based calculation algorithm for ophthalmic plaque brachytherapy using realistic and adaptable patient-specific eye geometries and materials. We used the MC code PENELOPE in EyeMC to model Bebig IsoSeed I25.S16 seeds in COMS plaques and 106 Ru/106 Rh applicators that are coupled onto a customizable eye model with realistic geometry and composition. To significantly reduce calculation times, we integrated EyeMC with CloudMC, a cloud computing platform for radiation therapy calculations. EyeMC is equipped with an evaluation module that allows the generation of isodose distributions, dose-volume histograms, and comparisons with Plaque Simulator three-dimensional dose distribution. We selected a sample of patients treated with 125 I and 106 Ru isotopes in our institution, covering a variety of different type of plaques, tumor sizes, and locations. Results from EyeMC were compared to the original plan calculated by the TPS Plaque Simulation, studying the influence of heterogeneous media composition as well. EyeMC calculations for Ru plaques agreed well with manufacturer's reference data and data of MC simulations from Hermida et al. (2013). Significant deviations, up to 20%, were only found in lateral profiles for notched plaques. As expected, media composition significantly affected estimated doses to different eye structures, especially in the 125 I cases evaluated. Dose to sclera and lens were found to be about 12% lower when considering real media, while average dose to tumor was 9% higher. 106 Ru cases presented a 1%-3% dose reduction in all structures using real media for calculation, except for the lens, which showed an average dose 7.6% lower than water-based calculations. Comparisons with Plaque Simulator calculations showed large differences in dose to critical structures for 106 Ru notched plaques. 125 I cases presented significant and systematic dose deviations when using the default calculation parameters from Plaque Simulator version 5.3.8., which were corrected when using calculation parameters from a custom physics model for carrier-attenuation and air-interface correction functions. EyeMC is a MC calculation system for ophthalmic brachytherapy based on a realistic and customizable eye-tumor model which includes the main eye structures with their real composition. Integrating this tool into a cloud computing environment allows to perform high-precision MC calculations of ocular plaque treatments in short times. The observed variability in eye anatomy among the selected cases justifies the use of patient-specific models.

MRI and dual-energy CT fusion anatomic imaging in Ru-106 ophthalmic brachytherapy

PurposeBrachytherapy with Ru-106 is widely used for the treatment of intraocular tumors, and its efficacy depends on the accuracy of radioactive plaque placement. Ru-106 plaques are MRI incompatible and create severe metal artifacts on conventional CT scans. Dual-energy CT scans (DECT) may be used to suppress such artifacts. This study examines the possibility of creating fusion images from MRI scans (preoperatively) and DECT scans (with the plaque in place) as a tool for confirming the anatomic accuracy of plaque placement. Methods and MaterialsSix patients with intraocular lesions (5 with choroidal melanoma and 1 with a retinal vasoproliferative lesion) were included. Fusion images of preoperative MRI scans and DECT scans with the plaque in place were created with the Demo version of the ImFusion suite (ImFusion GmbH, Munchen Germany). Clearance margins between the tumor and plaque edge in axial, transverse, and coronal planes as well as the elevation of the posterior plaque edge from the sclera were recorded and associated with the location of the lesion. ResultsPlaque-tumor clearance margins for transverse, sagittal, and coronal planes were higher for anteriorly located lesions (5.13 mm ± 0.11 [5.0–5.2], 5.10 mm ± 0.26 [4.9–5.4], and 5.33 mm ± 0.45 [4.9–5.8] respectively) than for posteriorly located lesions (4.16 mm ± 1.44 [2.5–5.1], 4.13 mm ± 1.42 [2.5–5.1], and 4.2 mm ± 1.21 [2.8–5.0], respectively). The elevation of the posterior plaque edge from the sclera was 0.33 mm ± 0.28 [0–0.5] and 0.63 mm ± 0.60 [0.7–1.2] for posterior and anterior lesions, respectively. ConclusionsFusion images between DECT and MRI scans may be used as a tool to confirm the accuracy of Ru-106 plaque placement in relation with the intraocular tumors in ophthalmic brachytherapy.

Ultrasound Biomicroscopy Documented Anterior Uveal Melanoma Regression after Ruthenium-106 Plaque Therapy

Introduction: Ultrasound biomicroscopy (UBM) is the only widely used method for the evaluation of anterior uveal melanoma (AUM). Objective: Documentation of regression of AUM treated with ruthenium-106 (Ru-106) plaque types CCB and CCC using UBM. Methods: This single institution-based retrospective case series involved 10 Caucasian patients with AUM followed after brachytherapy with UBM from January 2014 until February 2019. The largest prominence of the tumor perpendicular to the sclera or the cornea (including scleral/corneal thickness) (D) and the largest basal dimension (B) were measured in millimeters with UBM for all patients prior to the brachytherapy and at 4-month interval follow-up. Tumor regression was calculated as a percentage of decrease in the initial D and B values. Results: The study involved 10 patients with a mean age of 64.4 years (yr) (range 46–80 yr). D ranged from 1.82 to 5.5 mm (median 2.99 mm) and B from 2.32 to 12.38 mm (median 4.18 mm). The apical radiation dose in all patients was 100 Gy. The median follow-up was 42.02 months. Regression for D was 21.11 ± 13.66%, 31.09 ± 14.66%, and 34.92 ± 19.86% at 1st, 2nd, and 3rd year of the follow-up, respectively, while for B it was 21.58 ± 16.05%, 28.98 ± 17.71%, and 32.06 ± 18.96%, respectively. Tumor recurrence was documented in 2/10 patients. Conclusion: The major regression of AUM, treated with Ru-106 plaque types CCB and CCC, was documented in the first 2 years after brachytherapy in our study group. In the following years, only minimal regression was documented that warns of the need for close monitoring and active search for local recurrences.

Short-term changes of cornea and tear film after ruthenium-106 plaque therapy for intraocular tumors.

Purpose:Plaque therapy is a well-recognized treatment for intraocular tumors. In current study, we aimed to prospectively investigate the short-term effects of ruthenium 106 (Ru-106) plaque therapy on the cornea and ocular surface parameters.Methods:Twenty-five patients diagnosed with choroidal melanoma which undergone Ru-106 plaque therapy from 2016 to 2018 were included. Tear osmolarity, tear film break-up time, Schirmer test I, fluorescein dye staining based on Oxford staining method; Ocular Surface Disease Index (OSDI) questionnaire and corneal specular microscopy were performed. These tests were assessed preoperatively and then 3 months postoperatively.Results:The mean (±SD) age of subjects was 48.52 ± 15.18 years. The patients were followed for a mean(±SD) period of 3.64 ± 2.40 months. Total mean (+SD) delivered radiation dose to the tumor apex and total received radiation by the sclera was 83.20 ± 26.31 and 640.65 ± 472.69 Gray (Gy), respectively. In longitudinal analysis, OSDI score and Oxford staining score increased significantly (P = 0.002 for both variables) and the prevalence of dry eye disease (DED) increased from 20% preoperatively to 72% at 3 months postoperatively (P = 0.001).The changes in the all specular microscopy parameters were statistically nonsignificant (all P values > 0.05).Conclusion:There is a considerable increase in the rate of DED following plaque therapy for the treatment of choroidal melanoma in short-term follow-up. The OSDI questionnaire and fluorescein staining test are valuable tools for early detection of DED postoperatively.

Efficacy and complications of ruthenium-106 brachytherapy for uveal melanoma: a systematic review and meta-analysis.

PurposeThe aim of this study was to evaluate the efficacy and vision-threatening complications of brachytherapy with ruthenium-106 (106Ru) plaque to treat uveal melanoma.Material and methodsA literature review was performed based on results from searching PubMed, Embase, Web of Science, Scopus, and Cochrane databases, using the following key words: “choroidal melanoma”, “uveal melanoma”, “brachytherapy”, and “ruthenium-106”. We included studies performed on more than 30 patients since 1986, reporting on local control rate, complications rate, mean radiation dose, and mean tumor thickness. The cumulative analysis was performed using Metaprop command of Stata v.16, and meta-regression was conducted based on mean tumor thickness and mean radiation dose to tumor’s apex.ResultsTwenty-one retrospective studies were selected, involving 3,913 patients treated primarily with 106Ru plaque brachytherapy. The range of radiation dose to tumor apex was from 70 Gy to 250 Gy. The local control rate following brachytherapy ranged from 59% to 98%, and the overall weighted mean of local control was 84%. However, the heterogeneity between studies’ reports was remarkable (I2 = 95.40%). Meta-regression based on tumor thickness and mean dose of radiation to the apex showed that the studies’ heterogeneity was minimally related to the difference in mean tumor size (I2 = 92%). The correlation between larger tumor size and lower local control rate was statistically significant (p-value = 0.024). There was no significant correlation between the mean radiation dose and local control rate (p-value = 0.679). The most commonly reported complications were cataract and radiation-related retinopathy.ConclusionsAlthough the studies’ heterogeneity was high, in a prescription dose ranging from 70 Gy to 250 Gy to the tumor apex, 106Ru brachytherapy seems to be successful in local control of uveal melanoma. The efficacy of 106Ru in controlling uveal melanomas decreased with the increase in tumor thickness. However, these outcomes should be verified in randomized comparative studies.

Ru-106 plaque radiotherapy for vasoproliferative tumors of retina: a 15-year single-center experience.

This study evaluates the outcomes of ruthenium-106 (Ru-106) plaque brachytherapy for vasoproliferative tumors (VPTs) of the ocular fundus in a single referral ocular oncology center. The clinical charts of all patients diagnosed with VPT who underwent plaque radiotherapy from 2002 to 2017 were reviewed. Clinical features, types of treatment, outcomes and complications were evaluated. Of 46 patients with VPT diagnosis in our ocular oncology clinic, 25 (54.34%) cases were treated with Ru-106 plaque brachytherapy. Eleven patients (44%) were male, and the mean age at the time of diagnosis was 40.92 ± 13.11years. The mean follow-up time was 47.56 ± 36.87months. Inferotemporal quadrant was the most common site of the tumor (64.00%). The mean delivered apex and scleral dose was 101.56 ± 6.51 and 412.26 ± 113.66 Gray (Gy), respectively. Initial tumor length, width and thickness were 10.26 ± 3.42, 8.05 ± 2.83 and 4.27 ± 1.10mm, respectively. The mean tumor thickness decreased to 2.60 ± 0.63mm, postoperatively. Complete resolution of subretinal fluid around the tumor was achieved in 81.80% of cases. Visual acuity was more than 20/400 in 64% of patients before treatment and 60% of patients at last follow-up. Our study showed that Ru-106 plaque radiotherapy is an effective and safe method of treatment in VPTs.