Dose Distributions and Treatment Margins in Ocular Brachytherapy with 106Ru Eye Plaques

Wolfram-silicone implants as effective radiation shielding for ocular brachytherapy: dosimetric features and in vivo animal study on biocompatibility

OBJECTIVE

To evaluate wolfram as a photon and beta absorber in the management of uveal melanoma with radiotherapy, examining its potential ocular adverse effects and physiologic tolerance using an in vivo rabbit ocular model.

METHODS

A method of manufacturing implants from mixtures of wolfram and silicone was developed. Their shielding effect on the radiation of sources used in ocular brachytherapy was investigated by dosimetric measurement in an eye phantom as well as numerical simulations. Different wolfram implantation techniques, such as extraocular fixation of a wolfram-silicone implant (n = 1), vitrectomy with silicone oil and intravitreal injection of a wolfram-silicone oil suspension (n = 2), and concurrent attachment of a wolfram implant onto the sclera (n = 2), were tested to investigate the long-term effects of wolfram. A vitrectomy with silicone oil without wolfram implantation was carried out in 2 rabbits (n = 2), constituting the control group. The eyes were enucleated after 3 months for histologic analysis.

RESULTS

Wolfram-silicone mixtures have been dosimetrically proven to be very effective radiation absorbers for use in ocular brachytherapy. Severe complications, such as endophthalmitis, secondary glaucoma, cornea decompensation, and vessel occlusion, were not documented in the tested rabbit eyes after the application of wolfram. Histologic examination of the bulbi after enucleation showed epiretinal gliosis without further pathologic findings in all eyes after vitrectomy.

CONCLUSIONS

The results of this study show that wolfram and wolfram-silicone implants constitute a promising candidate as potential radiation shielding substrates.

Treatment-Related Complications and Functional Results after Ruthenium-106 Brachytherapy in Small to Medium Size Uveal Melanomas (Part 2)

PURPOSE

To analyze the treatment-related complications after ruthenium-106 brachytherapy in patients with uveal melanoma in terms of radiation-induced optic neuropathy, maculopathy and retinopathy, radiation-related vitreous hemorrhage, and retinal detachment, as well as secondary glaucoma and radiogenic cataract. In addition, the course of visual acuity was analyzed.

PATIENTS/METHODS AND MATERIALS

This retrospective study included 608 patients treated with ruthenium-106 brachytherapy between January 2008 and December 2010 at the Department of Ophthalmology, University Hospital Essen. The follow-up time was 11 years. The occurrence of the radiation-induced complications was analyzed using the Kaplan-Meier method. Cox regression was used for univariate and multivariate risk factor analyses. Hazard ratios were calculated for each variable.

RESULTS

Regarding the complications, 34% (N = 207) of the patients had no reported side effects or complications during follow-up. Radiation optic neuropathy was observed in 18.8% (N = 114) of the patients, with a median time to onset of 16 months (range: 3 - 78 months). Radiation maculopathy occurred in 8.2% (N = 50) after a median time of 17 months (range: 3 - 67 months). Radiation retinopathy was observed in 20.1% (N = 122), with a median time to onset of 21 months (range: 6 - 67 months). Secondary glaucoma developed in 9.7% of the patients (N = 53) and radiogenic cataract in 46.8% (N = 227). Vitreous hemorrhage (11.8%, N = 72) and scleral necrosis (2.1%, N = 13) occurred relatively rarely.

CONCLUSION

The observed radiogenic complication rate is comparable with that reported in previous studies.

Apical dose versus volume dose of Ruthenium-106 brachytherapy for uveal melanoma

OBJECTIVE

Ruthenium-106 brachytherapy is commonly used to treat uveal melanomas. Most centres prescribe a radiation dose to the tumour apex that is calculated with the tumour located in the centre of the plaque. Recent work suggests that D99%-the minimum radiation dose delivered to 99% of tumour volume-may be a better predictor of tumour control than apex dose. Both dosing regimens may be affected by tumour and treatment variables differently. We explored the effect of differences in these variables on volume and apex dose using a 3-dimensional planning model.

METHODS

The time required to deliver 100 Gy to the tumour apices of representative tumours ranging from 2- to 6-mm thickness with central plaque positioning was calculated in Plaque Simulator™. This treatment time was used for further calculations, including D99% with central plaque placement, and apical and tumour volume doses when tumour and plaque characteristics were altered, including eccentric plaque placement, either away from (tilt) or along (offset) scleral surface, tumour shape, and plaque type.

RESULTS

D99% was always greater than the apex dose when plaques were placed centrally, and the difference increased with tumour thickness. Increasing degrees of tumour offset reduced apical dose and D99%, with a greater effect on apical dose for thicker and D99% for thinner tumours, respectively. Differences in tumour shape and plaque type had idiosyncratic effects on apical and volume dosing.

CONCLUSION

D99% and apex dose are affected by tumour and treatment characteristics in different ways, highlighting the complexity of radiation delivery to uveal tumours.

Tumor- and Radiation-Related Complications after Ruthenium-106 Brachytherapy in Small to Medium Uveal Melanomas (Part 1)

PURPOSE

The purpose of this study was to analyze tumor-related complications after ruthenium-106 brachytherapy in patients with uveal melanoma, with respect to local tumor control, insufficient radiation response, enucleation, and metastasis rate.

PATIENTS/METHODS AND MATERIALS

This retrospective study included 608 patients treated consecutively with ruthenium-106 brachytherapy between January 2008 and December 2010 at the Department of Ophthalmology, University Hospital Essen. The occurrence of radiation-induced results was analyzed by estimating the risk by applying the Kaplan-Meier method, i.e., the "time to event" analysis. The Cox model test was used for the univariate and multivariate risk factor analyses. The median follow-up was 51 months after primary treatment.

RESULTS

Tumor recurrence was found in 21 patients (3.5%) and repeated treatment due to insufficient effect after the initial ruthenium-106 brachytherapy was performed in 40 patients (6.6%). The 5-year cumulative risk of recurrence was 4.0% and that of insufficient effect was 7.3%. Thirteen patients (2.1%) underwent a secondary enucleation; 8 because of a local recurrence and 5 because of severe post-brachytherapy complications. The cumulative enucleation risk was 2.3% after 5 years and 2.9% after 10 years, corresponding to eye preservation of 97.7 and 97.1%, respectively. In forty-two patients (7.2%), metastatic disease was diagnosed during the follow-up. The metastatic rate as calculated by the Kaplan-Meier method was 9.0, and 13.1% at 5 and 10 years, respectively.

CONCLUSION

Our study demonstrated that ruthenium-106 brachytherapy is an excellent treatment option for achieving local tumor control and eye preservation in well-selected patients. The metastatic rate is in agreement with that of previous studies analyzing small to medium size uveal melanomas.

GEC-ESTRO survey of 106Ru eye applicator practice for ocular melanoma - Physicist survey

AIM

106Ru eye plaque brachytherapy (BT, interventional radiotherapy) is an eye-preserving treatment for uveal melanoma performed in about 100 clinics worldwide. Despite this relatively low number, there is a considerable variation in clinical practice. In 2022, the BRAPHYQS and Head & Neck and Skin GEC-ESTRO working groups conducted a survey to map the current clinical practice. The survey consisted of a physicist and a physician part. This paper describes the physicist results. However, three physician questions with overlapping interest are included here as well.

MATERIALS AND METHODS

The survey questions pertained to commissioning and quality control (QC) of the plaques, treatment planning, radiobiological correction, as well as more general questions on practice improvement. The questions overlapping with the physician survey were related to dose prescription and margins.

RESULTS

Sixty-five physicist responses were included. A majority of the centres do not perform an independent measurement of the absorbed dose at reference depth, percentage depth dose (PDD) and off-axis data. A lack of calibration services and suitable equipment are the main reasons. About one third of the centres indicated that they do image based treatment planning. The use of margins and dose prescription showed a large variability, despite the availability of guidelines [1]. Many respondents expressed a strong wish for improvement in a wide range of aspects of clinical practice.

CONCLUSION

The physics survey showed a wide variability regarding quality control of the 106Ru sources and treatment planning practice.

Eight weeks of exercise intervention improves visuomotor and functional capacity, performance, and physiological profile in a patient with choroidal melanoma

The aim of this case study was to investigate the effects of an 8-wk combined exercise intervention, consisting of visual-coordinative and high-intensity interval training (HIIT), on the physical and visuomotor-functional capacity, performance, and physiological profile of a moderately active 29-yr-old man diagnosed with choroidal melanoma of the left eye. Data were collected on three occasions: at the initial diagnosis (T0), after hospitalization and radiotherapy treatment (T1), and following the recovery through the exercise intervention (T2), spanning a total of 17 wk. The primary outcome variables consisted of visuomotor and functional tests (VFTs), cardiorespiratory fitness (CRF), and microvascular circulation measured via flicker light-induced dilation (FiD). For visuomotor tests in general, a significant decline was observed between baseline T0 and T1 (by 6%-22%), followed by significant improvements at T2 (by 11%-36%), surpassing the initially observed T0 values. The cardiopulmonary exercise testing (CPET)-derived parameters exhibited a similar pattern, declining from T0 to T1 [by 8%-12% for peak V̇o2, peak power output (PO), and CPET duration, respectively], with a subsequent recovery observed in response to 8 wk of exercise training (T2), resulting in increases of 11%-25% for V̇o2, peak PO, and CPET duration. Interestingly, the dilation of both arteries and veins in response to the FiD stimulus exhibited a twofold increase compared with baseline levels. Our results suggest that the 8-wk exercise intervention improved patients' VFT and CRF profiles and exceeded baseline values. Additional investigation, particularly through randomized controlled trials, is needed to comprehensively explain changes in FiD.NEW & NOTEWORTHY Results presented here suggest that combined visual-coordinative and HIIT training improves the visual-functional capacity, performance, and physiological profile of choroidal melanoma patients during treatment recovery. This case study lays the groundwork for further research concerning exercise therapy in this unique patient population. In addition, further investigation is required to fully comprehend the combined effects of exercise and radiation therapy on vasculature and oxygenation in patients with choroidal melanoma.

Quantifying the effect of eccentric ruthenium plaque placement on tumor volume dose

Purpose

Ruthenium-106 brachytherapy is a common treatment for small to medium-sized uveal melanomas. In certain clinical contexts, plaques may be placed eccentrically to tumor center. The effect of plaque decentration, a common radiation dose measurement in radiotherapy: D98%, the percentage of the tumor volume receiving at least 98% of the prescribed dose (a commonly used term in radiation oncology), is unknown. We investigated this using two commonly used plaques (CCA and CCB; Eckert & Ziegler, BEBIG GmbH) in silico.

Material and methods

Using a Plaque Simulator™ (Eye Physics) plaque modelling software, treatment time required to deliver 100 Gy D98% with central plaque placement was calculated for both plaque models, treating tumors with basal dimensions of 10 mm (CCB plaque only) and 7 mm (CCA and CCB plaques), and a range of thicknesses. D98% was calculated for plaque-tumor edge distances of 0-5 mm. Additionally, we defined minimum plaque-tumor edge distances, at which D98% fell by 10% and 5% (safety margins).

Results

D98% decreased as plaque-tumor edge distance decreased, i.e. as plaque eccentricity increased. Minor (< 1 mm) plaque decentration caused minimal D98% changes across tumor thicknesses. Safety margins did not follow a consistent pattern.

Conclusions

Eccentric plaque placement reduces the radiation dose delivered to choroidal tumors. Both tumor (thickness, diameter) and plaque (size, location) characteristics are important D98% modulators. Further investigation of the effect of these characteristics and dose to organs at risk is essential.

Brachytherapy With 15- Versus 20-mm Ruthenium 106 Plaques Without Verification of Plaque Position Is Associated With Local Tumor Recurrence and Death in Posterior Uveal Melanoma

PURPOSE

Brachytherapy with episcleral plaques is the most common primary tumor treatment for uveal melanoma. This study aimed to compare the risk of tumor recurrence and metastatic death between 2 frequently used ruthenium 106 plaque designs: CCB (20.2 mm) and CCA (15.3 mm).

METHODS AND MATERIALS

Data were obtained from 1387 consecutive patients treated at St. Erik Eye Hospital, Stockholm, Sweden between 1981 and 2022 (439 with CCA and 948 with CCB plaques). During the period, scleral transillumination was performed to delineate tumor margins before plaque insertion, but accurate plaque positioning was not verified after scleral attachment, and no minimum scleral dose was used.

RESULTS

Patients treated with CCA plaques had smaller tumors than those treated with CCB plaques (mean diameter, 8.6 vs 10.5 mm; P < .001). There were no differences in patient sex, age, tumor distance to the optic disc, tumor apex dose, dose rate, or in rates of ciliary body involvement, eccentric plaque placement, or adjunct transpupillary thermotherapy (TTT). The average difference between plaque and tumor diameter was greater with the CCB plaque, and a smaller difference was an independent predictor of tumor recurrence. The 15-year incidence of tumor recurrence was 28% and 15% after treatment with CCA and CCB plaques, respectively (competing risk analysis, P < .001). Multivariate Cox regression analysis revealed a lower risk for tumor recurrence with CCB plaques (hazard ratio, 0.50). Similarly, patients treated with CCB plaques had a lower risk for uveal melanoma-related mortality (hazard ratio, 0.77). The risk for either outcome was not lower for patients treated with adjunct TTT. Uni- and multivariate time-dependent Cox regressions demonstrated that tumor recurrence was associated with uveal melanoma-related and all-cause mortality.

CONCLUSIONS

Compared with 20-mm plaques, brachytherapy with 15-mm ruthenium plaques is associated with a higher risk for tumor recurrence and death. These adverse outcomes may be avoided by increasing safety margins and implementing effective methods to verify accurate plaque positioning.

A Prognostic Score for the Prediction of Local Treatment Failure in Plaque Brachytherapy of Uveal Melanoma

Purpose

To develop a prognostic score that correlates to a low, medium, and high incidence of treatment failure after plaque brachytherapy of uveal melanoma (UM).

Methods and Materials

All patients who have received plaque brachytherapy for posterior UM at St. Erik Eye Hospital in Stockholm, Sweden from 1995 through 2019 were included (n = 1636). Treatment failure was defined as tumor recurrence, lack of tumor regression, or any other condition requiring a secondary transpupillary thermotherapy (TTT), plaque brachytherapy, or enucleation. The total sample was randomized into 1 training and 1 validation cohort, and a prognostic score for the risk for treatment failure was developed.

Results

In multivariate Cox regression, low visual acuity, tumor distance to the optic disc ≤2 mm, American Joint Committee on Cancer (AJCC) stage, and a tumor apical thickness of >4 (for Ruthenium-106) or >9 mm (for Iodine-125) were independent predictors of treatment failure. No reliable threshold could be identified for tumor diameter or cancer stage. In competing risk analyses of the validation cohort, the cumulative incidence of treatment failure, as well as of secondary enucleation, increased with the prognostic score: In the low, intermediate, and high-risk classes, the 10-year incidence of treatment failure was 19, 28, and 35% and of secondary enucleation 7, 19, and 25 %, respectively.

Conclusions

Low visual acuity, American Joint Committee on Cancer stage, tumor thickness, and tumor distance to the optic disc are independent predictors of treatment failure after plaque brachytherapy for UM. A prognostic score was devised that identifies low, medium, and high risk for treatment failure.

Individualized dosimetry in Ru-106 ophthalmic brachytherapy based on MRI-derived ocular anatomical parameters

PURPOSE

To estimate ocular geometry-related inaccuracies of the dosimetric plan in Ru-106 ophthalmic brachytherapy.

METHODS AND MATERIALS

Thirty patients with intraocular lesions were treated with brachytherapy using a Ru-106 plaque-shell of inner radius of 12 mm. Magnetic resonance imaging was employed to determine the external scleral radius at tumor site and the tumor margins. A mathematical model was developed to determine the distance between the external sclera and the internal surface of the plaque associated with the tangential application of the plaque on the treated eye. Differences in delivered dose to the tumor apex, sclera and tumor margins as derived by considering the default eye-globe of standard size (external sclera radius = 12 mm) against the individual-specific eye globe were determined.

RESULTS

The radius of external sclera at the tumor site was found to range between 10.90 and 13.05 mm for the patient cohort studied. When the patient specific eye-globe/tumor geometry is not taken into account, the delivered dose was found to be overestimated by 8.1% ± 4.1% (max = 15.3%) at tumor apex, by 1.5% ± 2.8% (max = 5.7%) at anterior tumor margin, by 16.6% ± 7.5% (max = 36.4%) at posterior tumor margin and 8.1% ± 3.8% (max = 13.2%) at central sclera of eyes with lower than the default radius. The corresponding dose overestimations for eyes with higher than the default radius was 13.5% ± 4.3% (max = 22.3%), 1.5% ± 2.8% (max = 5.7%), 12.6% ± 4.5% (max = 20.0%), and 15.1% ± 5.0% (max = 24.4%).

CONCLUSIONS

The proposed patient-specific approach for Ru-106 brachytherapy treatment planning may improve dosimetric accuracy. Individualized treatment planning dosimetry may prevent undertreatment of intraocular tumors especially for highly myopic or hyperopic eyes.

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

Background

To 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.

Methods

Medical 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.

Results

The 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).

Conclusions

Ru-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.

Outcomes following Notched Ruthenium-106 Plaque Brachytherapy for Juxtapapillary Choroidal Melanomas

Purpose

This study aimed to evaluate the outcomes of juxtapapillary choroidal melanomas treated with notched ruthenium-106 plaques.

Methods

Juxtapapillary choroidal melanomas (tumours within 2 disc diameters from the optic disc) treated with notched ruthenium-106 plaques (Eckert & Ziegler, BEBIG, Berlin, Germany) at the Scottish Ocular Oncology Service between 2009 and 2015 were retrospectively reviewed. The data were analysed with respect to various outcome measures including recurrence, complications, vision, and eye preservation.

Results

We reviewed 40 patients with a median tumour diameter of 8.4 mm (range 5-17 mm) and a median thickness of 2.5 mm (range 1.1-6 mm). AJCC tumour category distribution was 62.5% T1, 32.5% T2, and 5% T3 tumours. The mean presenting vision was 0.3 logMAR, and the mean final vision was 0.7 logMAR, with 62.5% retaining >1.0 logMAR and 50% retaining >0.3 logMAR at the final follow-up. The median follow-up was 51 months (14-100 months). Over the maximum follow-up time, 13 tumours (32.5%) recurred. Six of these were treated with salvage proton beam therapy (PBT), 2 with transpupillary thermotherapy followed by PBT, and 5 with enucleation. The final eye retention rate was 87.5%. Complications included maculopathy (10%), retinal detachment (5%), neovascular glaucoma (2.5%), and diplopia (2.5%). The observed risk of recurrence over 5 years was 31% (95% CI: 14.1%, 47.8%), and the risk of enucleation over 5 years was 11.5% (95% CI: 0.9%, 21.8%).

Conclusion

Juxtapapillary choroidal melanomas treated with notched ruthenium plaques have a high recurrence rate and frequently need salvage treatment with PBT for tumour control. This has led to a change in our practice toward offering PBT as the first-line treatment for these patients.

Long-term outcomes after enucleation or plaque brachytherapy of choroidal melanomas touching the optic disc

PURPOSE

To investigate local and systemic outcomes after enucleation, brachytherapy with ruthenium-106, iodine-125, notched and non-notched plaques and transpupillary thermotherapy (TTT) of choroidal melanomas touching the optic disc.

METHODS AND MATERIALS

All patients treated for choroidal melanoma touching the optic disc at St. Erik Eye Hospital, Stockholm, Sweden between 1984 and 2015 (n = 165) were included. Retrospective clinicopathological data was collected and 3D dosimetry performed.

RESULTS

Ninety-five patients (58 %) had been treated with ruthenium-106 brachytherapy, 21 (13 %) with iodine-125 brachytherapy and 49 (30 %) with enucleation. Median follow-up was 12.3 years. In simulations, some tumor areas were underdosed with non-notched plaques. Fifty of 116 patients (43 %) underwent a secondary brachytherapy (n = 5), enucleation (n = 29) or TTT (n = 16). In multivariate Cox Regressions, there were no significant differences in the risk for tumor progression or lack of regression between radioisotopes and notched and non-notched plaques. Adding TTT did not reduce the risk for a second treatment. The number of clock hours of circumpapillary tumor growth did not correlate to the risk for treatment failure or mortality. There were no significant differences in melanoma-related mortality for any treatment including enucleation. Kaplan-Meier disease-specific survival was 77 % at 5 years, 72 % at 10 years and 67 % at 20 years.

CONCLUSION

Plaque brachytherapy of choroidal melanomas touching the optic disc entails a two to threefold increased risk for treatment failure. This risk is similar between radioisotopes, notched and non-notched plaque designs and if TTT is used or not. The high rate of treatment failure does not lead to increased mortality.

Aflibercept for Radiation Maculopathy (ARM Study): Year-2 Extension of a Prospective Clinical Study

Purpose:

This work describes the 2-year results of the Aflibercept for Radiation Maculopathy (ARM) randomized clinical study that evaluated intravitreal vascular endothelial growth factor antagonist therapy in radiation maculopathy delivering aflibercept using a second-year collapsed, every-6-weeks, treat-and-adjust interval.

Methods:

Forty patients were enrolled in an institutional review board–approved clinical trial and randomly assigned to aflibercept treatment via 1 of 2 regimens: fixed, every-6-week treatment or variable, treat-and-adjust therapy centered around 6 weeks. All patients had a diagnosis of treated uveal melanoma with documented tumor control, and they had visually compromising radiation maculopathy. At conclusion of year 1, the first 30 patients were offered a collapsed single-arm variable of an every-6-weeks treat-and-adjust aflibercept injection schedule for an additional treatment year.

Results:

Baseline best-corrected visual acuity (BCVA) was 20/63 at ARM study entry 20/62 at the institution of the year-2 extension. At ARM study entry baseline, spectral domain–optical coherence tomography mean central retinal thickness was 432 µm and was 294 µm at the same institution. At the 2-year study’s conclusion, 76.7% (23 of 30) of eyes were better than 20/50, and only 6.7% (2 of 30) ended with a BCVA below 20/200. Final mean BCVA was 20/62 and final mean spectral domain–optical coherence tomography central retinal thickness was 286 µm, but as in year 1, this reduction in number of injections was not statistically significant.

Conclusions:

Aflibercept is effective in treating radiation maculopathy with maintained visual acuity at 2 years but continues to require an ongoing treatment approach to stabilize radiation maculopathy.

Scleral necrosis after brachytherapy for uveal melanoma: Analysis of risk factors

BACKGROUND

Radiation-induced scleral necrosis (RISN) is a rare, but a serious complication of brachytherapy for uveal melanoma. We aimed at analysing the incidence, timing and risk factors associated with development of RISN in a large institutional series.

METHODS

All consecutive cases with brachytherapy for uveal melanoma treated by the Departments of Ophthalmology and Radiotherapy at University Hospital Essen between 1999 and 2016 were eligible. Development of RISN during the post-treatment follow-up was recorded. A 1:2 propensity score matched case-control study was performed for the evaluation of the prognostic value of different tumour- and treatment-associated parameters.

RESULTS

RISN was documented in 115 (2.9%) of 3960 patients with uveal melanoma included in the final analysis, and occurred at the mean 30.3 months (range: 1.26-226 months) after brachytherapy. In the whole cohort, younger age (p = 0.042), plaque type (p = 0.001) and ciliary body involvement (p < 0.0001) were independently associated with the RISN occurrence. In the case-control study, multivariable weighted proportional hazard analysis discovered the association of the following additional tumour- and treatment-associated characteristics with RISN: posterior tumour margin anterior to equatorial region (p = 0.0003), extraocular tumour extension (p = <0.0001), scleral contact dose (p = <0.0001), conjunctival dehiscence after therapy (p = 0.0001), disinsertion of the superior rectus muscle (p = 0.001) and the glaucoma medication (p = 0.014).

CONCLUSIONS

Our study confirms RISN as a rare complication, which might occur even years later after the brachytherapy for uveal melanoma. Alongside with scleral dose five other tumour and therapy related factors predict the risk of RISN after brachytherapy for uveal melanoma were established.

Tumour control probability after Ruthenium-106 brachytherapy for choroidal melanomas

Purpose: Ruthenium-106 (Ru-106) brachytherapy is a common eye-preserving treatment for choroidal melanomas. However, a dose-response model describing the relationship between the actual delivered tumour dose and tumour control has, to the best of our knowledge, not previously been quantified for Ru-106 brachytherapy; we aimed to rectify this.Material and methods: We considered consecutive patients with primary choroidal melanomas, treated with Ru-106 brachytherapy (2005-2014). Dosimetric plans were retrospectively recreated using 3D image-guided planning software. Pre-treatment fundus photographies were used to contour the tumour; post-treatment photographies to determine the accurate plaque position. Patient and tumour characteristics, treatment details, dose volume histograms, and clinical outcomes were extracted. Median follow-up was 5.0 years. The relationship between tumour dose and risk of local recurrence was examined using multivariate Cox regression modelling, with minimum physical tumour dose (D99%) as primary dose metric.Results: We included 227 patients with median tumour height and largest base dimension of 4 mm (range 1-12, IQR 3-6) and 11 mm (range 4-23, IQR 9-13). The estimated 3 year local control was 82% (95% CI 77-88). Median D99% was 105 Gy (range 6-783, IQR 65-138); this was the most significant factor associated with recurrence (p < .0001), although tumour height, combined TTT and Ru-106 brachytherapy, and sex were also significant. The hazard ratio (HR) for a 10 Gy increase in D99% was 0.87 (95% CI 0.82-0.93). Using biological effective dose in the model resulted in no substantial difference in dose dependence estimates. Robustness cheques with D1-99% showed D99% to be the most significant dose metric for local recurrence.Conclusion: The minimum tumour dose correlated strongly with risk of tumour recurrence, with 100 Gy needed to ensure at least 84% local control at 3 years.

Predicting Visual Acuity Deterioration and Radiation-Induced Toxicities after Brachytherapy for Choroidal Melanomas

Ruthenium-106 (Ru-106) brachytherapy is an established modality for eye-preserving treatment of choroidal melanoma. To achieve optimal treatment outcomes, there should be a balance between tumour control and the risk of healthy tissue toxicity. In this retrospective study, we examined normal tissue complication probability (NTCP) for visual acuity deterioration and late complications to aid the understanding of dose-dependence after Ru-106 treatments. We considered consecutive patients diagnosed with choroidal melanoma and primarily treated at a single institution from 2005-2014. Treatment plans were retrospectively recreated using dedicated software and image guidance to contour the tumour and determine the actual plaque position. Dose distributions were extracted from each plan for all relevant anatomical structures. We considered visual acuity deterioration and late complications (maculopathy, optic neuropathy, ocular hypertension, vascular obliteration, cataract and retinal detachment). Lasso statistics were used to select the most important variables for each analysis. Outcomes were related to dose and clinical characteristics using multivariate Cox regressions analysis. In total, 227 patients were considered and 226 of those were eligible for analysis. Median potential follow-up time was 5.0 years (95% CI: 4.5-6.0). Visual acuity deterioration was related to optic disc-tumour distance and dose metrics from the retina and the macula, with retina V10Gy showing the strongest correlation. Macula V10Gy was the only dose metric impacting risk of maculopathy, while optic disc-tumour distance also proved important. Optic disc V50Gy had the largest impact on optic neuropathy along with optic disc-tumour distance. Optic disc V20Gy was the only variable associated with vascular obliteration. Lens D2% had the largest impact on the risk of cataract along with older age and the largest base dimension. We found no variables associated with the risk of ocular hypertension and retinal detachment. Visual acuity deterioration and most late complications demonstrated dependence on dose delivered to healthy structures in the eye after Ru-106 brachytherapy for choroidal melanomas.

Evaluation of Hungarian monitoring results and source localization of the 106Ru release in the fall of 2017

Anthropogenic ¹⁰⁶Ru has been detected in the environment from late September to early October 2017 by several European environmental radiological monitoring networks. The paper presents the comprehensive evaluation of Hungarian monitoring results related to the occurrence of ¹⁰⁶Ru in various environmental compartments (airborne particulates, deposition, plants, and terrestrial indicators), which was implemented to determine the temporal and spatial variation of the contaminant on a national scale and also to verify the findings based on the data arising from environmental monitoring at a local scale in Budapest. Difficulties in direct comparison of the diverse reported data were also considered; results arising from varied sampling periods were corrected with account taken of the relation between the sampling duration and 4-day-long plume residence (estimation based on the daily monitoring of air and backward trajectory analysis). Integrated analysis of air and deposition measurements and meteorological data was also performed; the deposition processes were investigated by establishing the correlations of activity concentrations measured in the atmosphere and in the deposition samples. In order to study the temporal distribution and spatial localization of the ¹⁰⁶Ru contamination and to interpret the measurements at ground level, backward trajectory analysis was performed with HYSPLIT model. The backward trajectory simulations suggested that the release had probably occurred during the last week of September 2017 from the geographical area between Volga and the Urals. In addition, assessment of the doses due to the ¹⁰⁶Ru release was implemented considering external exposure from cloudshine and groundshine and internal exposure via inhalation.

Aflibercept for Radiation Maculopathy Study: A Prospective, Randomized Clinical Study

PURPOSE

To evaluate 2 treatment approaches to intravitreal vascular endothelial growth factor antagonist therapy in radiation maculopathy comparing aflibercept delivered by either a 6-week treatment interval or treat-and-adjust interval.

DESIGN

Randomized, prospective clinical trial.

METHODS

Forty consecutive patients were enrolled in an institutional review board-approved clinical trial and randomized to aflibercept treatment via 1 of 2 regimens: (1) fixed, every-6-weeks treatment or (2) variable, treat-and-adjust treatment centered around 6 weeks. All patients had a diagnosis of treated uveal melanoma with documented tumor control. All patients showed visually compromising radiation maculopathy confirmed by a decline in best-corrected visual acuity (BCVA) and spectral-domain (SD) OCT documentation of radiation maculopathy.

MAIN OUTCOME MEASURES

Best-corrected visual acuity and SD OCT central retinal thickness at 1 year.

RESULTS

Thirty-nine of 40 patients completed the trial (97.5%) with 1 year of follow-up. Baseline study entry BCVA was 20/63 and was maintained at 20/62 at study conclusion at 60 weeks (1 year). At baseline, SD OCT mean central retinal thickness was 432 μm and improved to 294 μm at 60 weeks (P < 0.02). At the study conclusion, 42.5% of eyes (17/40) showed better than 20/50 BCVA, and only 5% of eyes (2/40) showed a BCVA worse than 20/200. In the every-6-weeks interval treatment arm, patients received 9 injections, whereas in the treat-and-adjust study arm, patients received 8.4 injections (P = 0.88, not significant). One patient experienced an inflammatory response after aflibercept injection, but this did not occur again for this patient, nor for any other study injections (1/400 injections [0.0025%]). No patients demonstrated endophthalmitis or metastatic disease or died during the study window.

CONCLUSIONS

Aflibercept seems to limit vision loss associated with radiation maculopathy. In this randomized, prospective clinical study, no difference was found between a fixed 6-week treatment interval and a variable treat-and-adjust interval because virtually all patients required treatment every 6 weeks and were not able to extend. Remarkably, almost half of all treated patients maintained BCVA of 20/50 or better throughout 1 year of treatment. Aflibercept is effective in treating radiation maculopathy, but requires an ongoing treatment approach.

Monte Carlo Simulation of the Treatment of Uveal Melanoma Using Measured Heterogeneous 106Ru Plaques

Background/Aims

Ruthenium plaques are used for the treatment of ocular tumors. The aim of this work is the comparison between simulated absorbed dose distributions tallied in an anthropomorphic phantom, obtained from ideal homogeneous plaques, and real eye plaques in which the actual heterogeneous distribution of ¹⁰⁶Ru was measured. The placement of the plaques with respect to the tumor location was taken into consideration to optimize the effectiveness of the treatment.

Methods

The generic CCA and CCB, and the specific CCA1364 and CCB1256 ¹⁰⁶Ru eye plaques were modeled with the Monte Carlo code PENELOPE. To compare the suitability of each treatment for an anterior, equatorial and posterior tumor location, cumulative dose-volume histograms for the tumors and structures at risk were calculated.

Results

Eccentric placements of the plaques, taking into account the inhomogeneities of the emitter map, can substantially reduce the dose delivered to structures at risk while maintaining the prescribed dose at the tumor apex.

Conclusions

The emitter map distribution of the plaque and the computerized tomography of the patient used in a Monte Carlo simulation allow an accurate determination of the plaque position with respect to the tumor with the potential to reduce the dose to sensitive structures.