Equivalent uniform RBE-weighted dose in eye plaque brachytherapy

BACKGROUND

Brachytherapy for ocular melanoma is based on the application of eye plaques with different spatial dose nonuniformity, time-dependent dose rates and relative biological effectiveness (RBE).

PURPOSE

We propose a parameter called the equivalent uniform RBE-weighted dose (EUDRBE) that can be used for quantitative characterization of integrated cell survival in radiotherapy modalities with the variable RBE, dose nonuniformity and dose rate. The EUDRBE is applied to brachytherapy with 125I eye plaques designed by the Collaborative Ocular Melanoma Study (COMS).

METHODS

The EUDRBE is defined as the uniform dose distribution with RBE = 1 that causes equal cell survival for a given nonuniform dose distribution with the variable RBE > 1. The EUDRBE can be used for comparison of cell survival for nonuniform dose distributions with different RBE, because they are compared to the reference dose with RBE = 1. The EUDRBE is applied to brachytherapy with 125I COMS eye plaques that are characterized by a steep dose gradient in tumor base-apex direction, protracted irradiation during time intervals of 3-8 days, and variable dose-rate dependent RBE with a maximum of about 1.4. The simulations are based on dose of 85 Gy prescribed to the farthest intraocular extent of the tumor (tumor apex). To compute the EUDRBE in eye plaque brachytherapy and correct for protracted irradiation, the distributions of physical dose have been converted to non-uniform distributions of biologically effective dose (BED) to include the biological effects of sublethal cellular repair, Our radiobiological analysis considers the combined effects of different time-dependent dose rates, spatial dose non-uniformity, dose fractionation and different RBE and can be used to derive optimized dose regimens brachytherapy.

RESULTS

Our simulations show that the EUDRBE increases with the prescription depths and the maximum increase may achieve 6% for the tumor height of 12 mm. This effect stems from a steep dose gradient within the tumor that increases with the prescription depth. The simulations also show that the EUDRBE increase may achieve 12% with increasing the dose rate when implant duration decreases. The combined effect of dose nonuniformity and dose rate may change the EUDRBE up to 18% for the same dose prescription of 85 Gy to tumor apex. The absolute dose range of 48-61 Gy (RBE) for the EUDRBE computed using 4 or 5 fractions is comparable to the dose prescriptions used in stereotactic body radiation therapy (SBRT) with megavoltage X-rays (RBE = 1) for different cancers. The tumor control probabilities in SBRT and eye plaque brachytherapy are very similar at the level of 80% or higher that support the hypothesis that the selected approximations for the EUDRBE are valid.

CONCLUSIONS

The computed range of the EUDRBE in 125I COMS eye plaque brachytherapy suggests that the selected models and hypotheses are acceptable. The EUDRBE can be useful for analysis of treatment outcomes and comparison of different dose regimens in eye plaque brachytherapy.

Prediction model of radiotherapy outcome for Ocular Adnexal Lymphoma using informative features selected by chemometric algorithms

BACKGROUND

Ocular Adnexal Lymphoma (OAL) is a non-Hodgkin's lymphoma that most often appears in the tissues near the eye, and radiotherapy is the currently preferred treatment. There has been a controversy regarding the prognostic factors for systemic failure of OAL radiotherapy, the thorough evaluation prior to receiving radiotherapy is highly recommended to better the patient's prognosis and minimize the likelihood of any adverse effects.

PURPOSE

To investigate the risk factors that contribute to incomplete remission in OAL radiotherapy and to establish a hybrid model for predicting the radiotherapy outcomes in OAL patients.

METHODS

A retrospective chart review was performed for 87 consecutive patients with OAL who received radiotherapy between Feb 2011 and August 2022 in our center. Seven image features, derived from MRI sequences, were integrated with 122 clinical features to form comprehensive patient feature sets. Chemometric algorithms were then employed to distill highly informative features from these sets. Based on these refined features, SVM and XGBoost classifiers were performed to classify the effect of radiotherapy.

RESULTS

The clinical records of from 87 OAL patients (median age: 60 months, IQR: 52-68 months; 62.1% male) treated with radiotherapy were reviewed. Analysis of Lasso (AUC = 0.75, 95% CI: 0.72-0.77) and Random Forest (AUC = 0.67, 95% CI: 0.62-0.70) algorithms revealed four potential features, resulting in an intersection AUC of 0.80 (95% CI: 0.75-0.82). Logistic Regression (AUC = 0.75, 95% CI: 0.72-0.77) identified two features. Furthermore, the integration of chemometric methods such as CARS (AUC = 0.66, 95% CI: 0.62-0.72), UVE (AUC = 0.71, 95% CI: 0.66-0.75), and GA (AUC = 0.65, 95% CI: 0.60-0.69) highlighted six features in total, with an intersection AUC of 0.82 (95% CI: 0.78-0.83). These features included enophthalmos, diplopia, tenderness, elevated ALT count, HBsAg positivity, and CD43 positivity in immunohistochemical tests.

CONCLUSION

The findings suggest the effectiveness of chemometric algorithms in pinpointing OAL risk factors, and the prediction model we proposed shows promise in helping clinicians identify OAL patients likely to achieve complete remission via radiotherapy. Notably, patients with a history of exophthalmos, diplopia, tenderness, elevated ALT levels, HBsAg positivity, and CD43 positivity are less likely to attain complete remission after radiotherapy. These insights offer more targeted management strategies for OAL patients. The developed model is accessible online at: https://lzz.testop.top/.

A generalized model for monitor units determination in ocular proton therapy using machine learning: A proof-of-concept study

Objective.Determining and verifying the number of monitor units is crucial to achieving the desired dose distribution in radiotherapy and maintaining treatment efficacy. However, current commercial treatment planning system(s) dedicated to ocular passive eyelines in proton therapy do not provide the number of monitor units for patient-specific plan delivery. Performing specific pre-treatment field measurements, which is time and resource consuming, is usually gold-standard practice. This proof-of-concept study reports on the development of a multi-institutional-based generalized model for monitor units determination in proton therapy for eye melanoma treatments.Approach.To cope with the small number of patients being treated in proton centers, three European institutes participated in this study. Measurements data were collected to address output factor differences across the institutes, especially as function of field size, spread-out Bragg peak modulation width, residual range, and air gap. A generic model for monitor units prediction using a large number of 3748 patients and broad diversity in tumor patterns, was evaluated using six popular machine learning algorithms: (i) decision tree; (ii) random forest, (iii) extra trees, (iv) K-nearest neighbors, (v) gradient boosting, and (vi) the support vector regression. Features used as inputs into each machine learning pipeline were: Spread-out Bragg peak width, range, air gap, fraction and calibration doses. Performance measure was scored using the mean absolute error, which was the difference between predicted and real monitor units, as collected from institutional gold-standard methods.Main results.Predictions across algorithms were accurate within 3% uncertainty for up to 85.2% of the plans and within 10% uncertainty for up to 98.6% of the plans with the extra trees algorithm.Significance.A proof-of-concept of using machine learning-based generic monitor units determination in ocular proton therapy has been demonstrated. This could trigger the development of an independent monitor units calculation tool for clinical use.

Generation and comparison of 3D dosimetric reference datasets for COMS eye plaque brachytherapy using model-based dose calculations

PURPOSE

A joint Working Group of the American Association of Physicists in Medicine (AAPM), the European Society for Radiotherapy and Oncology (ESTRO), and the Australasian Brachytherapy Group (ABG) was created to aid in the transition from the AAPM TG-43 dose calculation formalism, the current standard, to model-based dose calculations. This work establishes the first test cases for low-energy photon-emitting brachytherapy using model-based dose calculation algorithms (MBDCAs).

ACQUISITION AND VALIDATION METHODS

Five test cases are developed: (1) a single model 6711 125 I brachytherapy seed in water, 13 seeds (2) individually and (3) in combination in water, (4) the full Collaborative Ocular Melanoma Study (COMS) 16 mm eye plaque in water, and (5) the full plaque in a realistic eye phantom. Calculations are done with four Monte Carlo (MC) codes and a research version of a commercial treatment planning system (TPS). For all test cases, local agreement of MC codes was within ∼2.5% and global agreement was ∼2% (4% for test case 5). MC agreement was within expected uncertainties. Local agreement of TPS with MC was within 5% for test case 1 and ∼20% for test cases 4 and 5, and global agreement was within 0.4% for test case 1 and 10% for test cases 4 and 5.

DATA FORMAT AND USAGE NOTES

Dose distributions for each set of MC and TPS calculations are available online (https://doi.org/10.52519/00005) along with input files and all other information necessary to repeat the calculations.

POTENTIAL APPLICATIONS

These data can be used to support commissioning of MBDCAs for low-energy brachytherapy as recommended by TGs 186 and 221 and AAPM Report 372. This work additionally lays out a sample framework for the development of test cases that can be extended to other applications beyond eye plaque brachytherapy.

Monte Carlo investigation of dose distribution of uniformly and non-uniformly loaded standard and notched eye plaques

To investigate the effect of using non-uniform loading and notched plaques on dose distribution for eye plaques. Using EGSnrc Monte Carlo (MC) simulations, we investigate eye plaque dose distributions in water and in an anatomically representative eye phantom. Simulations were performed in accordance with TG43 formalism and compared against full MC simulations which account for inter-seed and inhomogeneity effects. For standard plaque configurations, uniformly and non-uniformly loaded plaque dose distributions in water showed virtually no difference between each other. For standard plaque, the MC calculated dose distribution in planes parallel to the plaque is narrower than the TG43 calculation due to attenuation at the periphery of the plaque by the modulay. MC calculated the dose behind the plaque is fully attenuated. Similar results were found for the notched plaque, with asymmetric attenuation along the plane of the notch. Cumulative dose volume histograms showed significant reductions in the calculated MC doses for both tumor and eye structures, compared to TG43 calculations. The effect was most pronounced for the notch plaque where the MC dose to the optic nerve was greatly attenuated by the modulay surrounding the optic nerve compared to the TG43. Thus, a reduction of optic nerve D95% from 14 to 0.2 Gy was observed, when comparing the TG43 calculation to the MC result. The tumor D95% reduced from 89.2 to 79.95 Gy for TG43 and MC calculations, respectively. TG43 calculations overestimate the absolute dose and the lateral dose distribution of both standard and notched eye plaques, leading to the dose overestimation for the target and organs at risk. The dose matching along the central axis for the non-uniformly loaded plaques to that of uniformly loaded ones was found to be sufficient for providing comparable coverage and can be clinically used in eye-cancer-busy centers.

Visual outcome and ocular complications in patients with lacrimal gland carcinoma after eye-sparing surgery and adjuvant radiation therapy

BACKGROUND

We report visual outcomes and ocular complications in patients with lacrimal gland carcinoma who had eye-sparing surgery followed by radiotherapy.

METHODS

This review included consecutive patients with lacrimal gland carcinoma who underwent eye-sparing surgery and adjuvant radiotherapy or concurrent chemoradiation therapy between 2007 and 2018. Clinical data, including details of ophthalmological examinations and radiation treatment were reviewed.

RESULTS

The study included 23 patients, 15 males and 8 females, with median age 51 years. Twenty patients (87%) received intensity-modulated proton therapy; 3 (13%) received intensity-modulated radiotherapy. Nineteen patients (83%) received concurrent chemotherapy. After a median follow-up time of 37 months (range: 8-83), 13 patients (57%) had best-corrected visual acuity 20/40 or better, 3 (13%) had moderate vision loss (between 20/40 and 20/200) and 7 (30%) had severe vision loss (20/200 or worse). The most common ocular complications were dry eye disease (21 patients; 91%), radiation retinopathy (16; 70%) and cataract progression (11; 49%). Tumour crossing the orbital midline (p=0.014) and Hispanic ethnicity (p=0.014) were associated with increased risk of severe vision loss. The risk of radiation retinopathy was significantly different among the three racial groups; Hispanic patients (n=3) had the highest rate of retinopathy (p<0.001). Tumour size, initial T category and total prescribed radiation dose were not significantly associated with severe vision loss.

CONCLUSION

Eye-sparing surgery followed by adjuvant radiotherapy in patients with lacrimal gland carcinoma has a reasonable overall visual prognosis. Patients with tumours crossing the orbital midline and Hispanic patients have a higher risk of severe vision loss.

Modernization of safety environment for a dedicated beamline for proton ocular therapy

BACKGROUND

Proton therapy is an effective treatment for ocular melanoma, and other tumors of the eye. The fixed horizontal beamline dedicated to ocular treatments at Massachusetts General Hospital was originally commissioned in 2002, with much of the equipment, safety features, and practices dating back to an earlier implementation at Harvard Cyclotron in the 1970s.

PURPOSE

To describe the experience of reevaluation and enhancement of the safety environment for one of the longest continuously operating proton therapy programs.

METHODS

Several enhancements in quality control had been introduced throughout the years of operation, as described in this manuscript, to better align the practice with the evolving standards of proton therapy and the demands of a modern hospital. We spotlight the design and results of the failure mode and effect analysis (FMEA), and subsequent actions introduced to mitigate the modes associated with elevated risk. The findings of the FMEA informed the specifications for the new software application, which facilitated the improved management of the treatment workflow and the image-guidance aspects of ocular treatments.

RESULTS

Eleven failure modes identified as having the highest risk are described. Six of these were mitigated with the clinical roll-out of a new application for image-guided radiation therapy (IGRT). Others were addressed through task automation, the broader introduction of checklists, and enhancements in pre-treatment staff-led time-out.

CONCLUSIONS

Throughout the task of modernizing the safety system of our dedicated ocular beamline, FMEA proved to be an effective instrument in soliciting inputs from the staff about safety and workflow concerns, helping to identify steps associated with elevated failure risks. Risks were reduced with the clinical introduction of a new IGRT application, which integrates quality management tools widely recognized for their role in risk mitigation: automation of the data transfer and workflow steps, and with the introduction of checklists and redundancy cross-checks.

Hydrogen nanobubbles: A novel approach toward radio-sensitization agents

BACKGROUND

Ocular melanoma is a rare kind of eye malignancy that threatens the patient's eyesight. Radiotherapy and surgical removal are the most commonly used therapeutic modalities, and nanomedicine has lately entered this field. Brachytherapy using Ruthenium-106 (106 Ru) ophthalmic plaques has been used for decades to treat ocular melanoma, with the applicator placed on the patient's eyes until the prescribed dose reaches the tumor apex.

PURPOSE

To investigate the efficiency of hydrogen nanobubbles (H2 -NBs) employment during intraocular melanoma brachytherapy using a 106 Ru electron emitter plaque.

METHODS

The Monte Carlo (MC) simulation and experimental investigation using a 3D-designed phantom and thermoluminescence dosimetry (TLD) were employed. Various concentrations of H2 -NBs with a diameter of 100 nm were simulated inside tumor tissue. The results were presented as deposited energy and dose enhancement factor (DEF). An equivalent Resin phantom of the human eyeball was made using AutoCAD and 3D-Printer technologies. The glass-bead TLDs dosimeter were employed and placed inside the phantom.

RESULTS

Using a 1% concentration of H2 -NBs, a DEF of 93% and 98% were achieved at the tumor apex of 10 mm from the experimental setup and MC simulation, respectively. For simulated concentrations of 0.1%, 0.3%, 0.5%, 1%, and 4% H2 -NBs, a maximum dose enhancement of 154%, 174%, 188%, 200%, and 300% were achieved, respectively, and a dose reduction was seen at about 3 mm from the plaque surface.

CONCLUSION

H2 -NBs can be used as an absorbed dose enhancer in 106 Ru eye brachytherapy because of their unique physical characteristics. Reducing plaque implantation time on the patient's eye, reducing sclera absorbed dose, and decreasing the risk of patients' healthy organs irradiation are reported as some of the potential benefits of using H2-NBs.

Stereotactic radiosurgery for recurrent pleomorphic adenoma of the lacrimal gland: a case report

Lacrimal gland pleomorphic adenomas (LGPAs) are common, benign, and intraorbital tumours that cause exophthalmos, ptosis, and visual disturbances. The curative treatment for LGPAs is gross total resection, and radiotherapy is considered adjunctive for recurrence or an alternative for inoperable LGPAs. Stereotactic radiosurgery (SRS) can be used for precise delivery of high radiation doses to the tumour, crucial in the treatment of intra-and extracranial neoplasms. Here, we present a 95-year-old woman who had a rapidly growing, recurrent LGPA and was successfully treated with SRS. The tumour was controlled without any adverse events over 21 months following SRS. SRS is a potential alternative treatment for recurrent LGPA.

Safety and efficacy of indigenously developed Ruthenium-106 eye plaque for brachytherapy of a spectrum of ocular tumors: A case series

ABSTRACT

Various treatment modalities are available for treatment of ocular tumors, which include chemotherapy, laser, and radiotherapy (external beam radiation therapy or brachytherapy). Brachytherapy using plaque applicator is preferred over external beam radiation therapy when the tumor is well localized, as this therapy delivers radiation dose to the tumor with lower doses to normal tissues in the vicinity. However, plaque therapy is expensive and beyond the reach of many poor patients in India. The Bhabha Atomic Research Center (BARC) recently introduced an indigenous Ruthenium-106 plaque to make brachytherapy treatment available and affordable to all needy patients in India. In the present case series, we report our experience using the indigenous Ru-106 plaque for the treatment of a spectrum of ocular tumors.

Examining the utility of lower dose radiotherapy for localised primary ocular adnexal MALT lymphoma

INTRODUCTION

Most primary ocular adnexal lymphomas are those involving mucosa-associated lymphoid tissue (MALT). Radiotherapy (RT) dose regimens in the literature vary from the historically used high doses (up to 56 Gy) to lower dose RT. We aimed to examine our institution's experience with the use of orbital RT for treating early-stage primary ocular adnexal MALT lymphoma (POAML).

METHODS

Patients treated for stage I or II POAML over a 12-year period (July 2006 to June 2018) were identified through institutional databases. Data were retrospectively collated through review of patient records. Descriptive statistical methods were employed to analyse the data.

RESULTS

Eighteen patients (median age of 67; range 44-87yrs) with localised POAML (3 cases of bilateral disease) were identified, resulting in a total of 21 evaluable orbits. Eight (44%) patients were female, and all were documented to be of good performance status (ECOG 0-1). The median follow-up was 34 months (range 8-75 months). The commonest dose fractionation used was 20 Gy in 10 fractions (n = 13 orbits) and a 3D conformal or volumetric modulated arc therapy (VMAT) technique was used in the majority of cases. None of the patients experienced an in-field recurrence. One patient had experienced a contralateral orbital recurrence two years post-unilateral orbital RT for orbital MALT lymphoma. Three patients experienced distant relapse.

CONCLUSION

The use of lower dose orbital RT such as 20 Gy in 10 fractions (or radio biologically equivalent) yields excellent local disease control in the management of ocular adnexal MALT lymphoma. The durability of the response appears to be favourable. Given the indolent nature of the disease and the low levels of toxicity associated with lower dose orbital RT, this regimen remains our favoured approach to the management of localised POAML.

Surface dose rate variations in planar and curved geometries of 106Ru/106Rh plaque sources for ocular tumors

PURPOSE

Investigation of surface dose rate variation with respect to the source configuration of ¹⁰⁶Ru/¹⁰⁶Rh eye plaque. To explore an alternate way to determine activity of brachytherapy plaques.

METHODS

The surface dose rates of ¹⁰⁶Ru/¹⁰⁶Rh plaque developed indigenously were measured by extrapolation chamber. To rule out possibility of any error in the activity distribution and quantity, same source was used in two different configurations namely planar and curved. EBT3 Gafchromic film was used for determination of uniformity in activity. Monte Carlo-based Codes EGSnrc and FLUKA were used to calculate dose rate in tissue, percentage depth dose and for determination of activity. Parameters and correction factors were estimated using simulations.

RESULTS

The measured reference absorbed dose rates for planar and curved ¹⁰⁶Ru/¹⁰⁶Rh eye plaques are found to be 589 ± 29 mGy/h and 560 ± 28 mGy/h, respectively. The difference in the reference absorbed dose rate of curved eye plaque is about ~5% as compared to planar configuration. The FLUKA-calculated dose values are almost independent of cavity length of the extrapolation chamber for both eye plaques. The FLUKA-based dose rates per μCi ¹⁰⁶Ru/¹⁰⁶Rh are about 17.28 ± 0.08 mGy/h and 16.48 ± 0.06 mGy/h, respectively for planar and curved eye plaques which match well with the measurements. The calculated activities for planar and curved eye plaques are 34.08 μCi and 33.98 μCi, respectively.

CONCLUSIONS

Surface dose rates for a prototype ¹⁰⁶Ru/¹⁰⁶Rh eye plaque with different configurations were estimated using simulations and measured experimentally. An alternate way to determine activity of beta-gamma brachytherapy plaque has been proposed.

Surgical and Ophthalmologic Outcomes of Reconstruction in Patients Treated With Eye-Sparing Surgery and Radiation Therapy for Tumors of the Lacrimal Drainage Apparatus

INTRODUCTION

Tumors involving the lacrimal drainage apparatus can be effectively treated with oncologic eye-sparing resection, immediate reconstruction, and adjuvant radiation. The extirpative technique is well described, whereas the reconstructive approach and outcomes are limited and largely anecdotal. The present study describes the largest series in the literature evaluating outcomes after reconstruction after globe-preserving oncologic resection.

METHODS

A retrospective review was performed for all patients undergoing reconstruction after resection of lacrimal gland tumors from 2008 to 2019. Reconstruction and ophthalmologic outcomes were assessed.

RESULTS

Of the 17 patients included, 2 underwent complex repair, 6 were reconstructed with a locoregional flap, and 9 underwent free flap reconstruction. All patients were treated with adjuvant radiation therapy. The median follow-up was 19 months (range, 5-126 months). Defects reconstructed with free flaps had lower rates of wound dehiscence and fistula formation compared with those reconstructed with other techniques (11% vs 25%, P = 0.45). Patients undergoing reconstruction with free tissue transfer also tended to have lower rates of ectropion, keratopathy and decreased visual acuity compared with those undergoing nonmicrosurgical reconstruction (33% vs 50%, P = 0.48; 11% vs 38%, P = 0.20; 56% vs 75%, P = 0.40, respectively). These differences were not statistically significant.

CONCLUSIONS

This is the first study to compare reconstructive and functional outcomes of nonmicrosurgical reconstruction and microsurgical free tissue transfer in the setting of eye-sparing surgery for tumors of the lacrimal drainage apparatus. Although various reconstructive options are feasible, microsurgical free tissue transfer is often used at our center and is associated with reliable outcomes.

Treatment outcomes after definitive radio(chemo)therapy for 17 lacrimal sac squamous cell carcinoma

OBJECTIVES

Tumors of the lacrimal sac are rare and life-threatening. Because of their rarity, no extensive clinical data on their management and prognosis exist. We investigated the application of definitive radiation therapy and its outcome in patients with lacrimal sac squamous cell carcinoma (LSSCC).

METHODS

We retrospectively studied 17 patients with LSSCC at a single institution between 2003 and 2017. All the patients were treated with definitive radiotherapy, and 11 patients were delivered with cisplatin-based chemotherapy. The patients' clinical records were reviewed for symptoms, pathological types, the volume and dosimetry of the tumors and their adjacent structures, radiation coverage of lymph node drainage areas, treatment outcomes, and complications from definitive radiotherapy.

RESULTS

Median follow-up was 38.9 months, and age at diagnosis was 48 years.The 2-year and 5-year overall survival, progression-free survival, locoregional control, and disease metastasis-free survival rates were 94.1 and 84.7%, 88.2 and 73.5%, 93.8%, 94.1, and 78.4%, respectively. A total dose of 6600-7000 cGy was prescribed to the tumor. Levels Ⅰb, Ⅶa, Ⅷ, and Ⅸ were covered with the clinical target volume regardless of lymph involvement. Acute Grade 3 radiation dermatitis occurred in seven patients (17.6%), but no acute Grade 4 or Grade 5 toxicity of any type occurred. Seven (41.2%, 7/17) of the treated eyes had moderated vision impairments; 17.6% (3/17) of patients developed cataracts, and glaucoma and radiation retinopathy were found in 5.9% (1/17) of patients.

CONCLUSIONS

Definitive radiotherapy could be a treatment option for those who refuse surgery or have unresectable LSSCC.

ADVANCES IN KNOWLEDGE

Radiation alone is a treatment option for LSSCC.

Occurrence of Phosphenes in Patients Undergoing Proton Beam Therapy for Ocular Tumor

PURPOSE

Phosphenes are frequently reported by patients irradiated in the head and neck area. The aim of the present study was to characterize and investigate potential mechanisms of proton beam therapy (PBT)-induced phosphenes in a large population of patients undergoing PBT for ocular tumors.

DESIGN

Prospective cohort study.

METHODS

Consecutive patients who underwent PBT in a single center were included. Immediately after the first session, all patients completed a questionnaire collecting information about the presence of phosphenes as well as their color, shape, and duration. Patient, tumor and treatment characteristics (dose volume histograms) were also collected.

RESULTS

Among the 474 patients included, 62.8% reported phosphenes during the first session of PBT. Reported colors were mainly blue-violet (70.5%) and white (14.1%). The prevalence of phosphenes was higher in younger patients (P = .003); other patient or ocular characteristics were not associated with the occurrence of phosphenes. Irradiation of the macula (P < .001) and/or optic disc (P < .001) were significantly associated with the presence of phosphenes, whereas blue-violet color was only associated with young age and irradiation of macular area (P = .04). Pupillary constriction was reported for 57.1% of patients with phosphenes vs 18.5% of patients without (P < .001). Blue-violet phosphenes (P < .001) and irradiation of macula (P = .001) were statistically associated with pupillary constriction.

CONCLUSIONS

The present study reported a high rate of phosphenes in patients irradiated by PBT for ocular tumor. Their blue-violet color and their association with a pupillary constriction probably indicates the stimulation of S-cones and retinal ganglion cells that reflects the activation of the afferent visual pathway.

Treating synchronous bilateral ocular adnexal marginal zone lymphoma: the consortium for improving survival of lymphoma study

Both-side synchronous involvement has been reported to account for 7-24% of ocular adnexal marginal zone lymphoma (OAML). We conducted a retrospective analysis to identify the clinical features and treatment outcomes of synchronous bilateral OAML (SB-OAML) by treatment modality. We analyzed patients with a histologic diagnosis of SB-OAML, excluding metachronous bilateral involved OAML. We enrolled a total of 95 patients for this analysis, 36 males and 59 females; the median patient age was 42 years (range 16-77 years). Eleven (11.6%) patients had been treated with chemotherapy or chemo-immunotherapy (eight R-CVP, two CVP, and one R-CHOP). The median number of treatments was 6 (range 6-8); there were 9 complete responses (CRs; 81.8%) and 2 partial responses (PRs; 18.2%). Nearly all patients (88.4%) received radiotherapy in both eyes, and the median radiation dose was 27 Gy (range 20-40 Gy) to each eye; 68 CRs (80.9%) and 14 PRs (16.7%) were achieved. Ten-year progression-free survival (PFS) and overall survival (OS) rates were 79.8 and 91.1%, respectively. Radiotherapy continued to be an independent prognostic marker, with the hazard of progression (P = 0.036). Eleven patients (13.1%) had surgery for cataract treatment during follow-up, and patients who received low-dose radiation (< 30.3 Gy) experienced fewer cataract operations. SB-OAML was predominantly observed in young females, and they had good response and prognosis regardless of treatment modalities. Low-dose radiotherapy to both eyes showed a tendency of longer PFS than did chemotherapy and could decrease cataract operations.

Proton Beam Irradiation for Treatment of Experimental Human Retinoblastoma

Proton beam irradiation was used to treat human retinoblastoma (Y-79 cell line) grown subcutaneously in the athymic "nude" mouse. Thirty-four tumors were included in the experimental groups, of which twenty-three were irradiated and eleven served as controls. Tumors were irradiated with protons produced at the 160 megavolts Harvard cyclotron. The dose delivered to the tumor ranged from 7.5 to 27.5 proton gray in a single treatment, and 25.0 proton gray delivered in two fractions separated by 24 hours. Reduction of tumor growth was significantly greater than controls (p less than 0.001) with treatment doses greater than or equal to 17.5 proton gray. Histologic examination revealed a marked decrease of mitotic activity in all specimens examined 48 hours after treatment at these higher doses. Total regression without evidence of remaining malignant cells was noted in three tumors treated at 17.5 proton gray or above. Our results indicate that human retinoblastoma in a murine host, with a tumor mass similar to that seen in a clinical setting, is sensitive to radiation by high energy protons.

Gamma knife radiosurgery for basal cell carcinoma of the eyelid: report of a case

Basal cell carcinoma (BCC) is the most common malignancy in the face. Surgical removal and reconstruction is the first choice of treatment options for BCC, but it tends to be invasive and sometimes is accompanied by a drastic change in appearance. We report here a case of BCC in the eyelid of a patient who was successfully treated by gamma knife radiosurgery (GKRS). He was 88 years old at this time. The ulcer disappeared within 3 weeks after GKRS and was covered with normal epithelium. This is the first report to describe an eyelid BCC that was treated by GKRS.

Late Effect of External Eye Irradiation on Choroidal Circulation

PURPOSE

To report two cases of atypical late onset radiation chorioretinopathy occurring 15 and 25 years post exposure and the indocyanine green (ICG) angiographic findings in these patients.

METHODS

Clinical examination and imaging including fluorescein and ICG angiography were performed.

RESULT

Fundus examination of the first patient revealed microangiopathy with intraretinal hemorrhages, lipid exudation, telangiectatic and aneurysmal capillary changes. Indocyanine green angiography showed an apparent chorioretinal anastomosis and delayed perfusion of the choriocapillaris. Fundus examination of the second patient revealed a pigment epithelial detachment and retinal pigment epithelial changes. Indocyanine green angiography showed atypical, tortuous, dilated, choroidal vessels as well as areas of hypoperfusion. Both patients had multiple dot-like hyperfluorescent spots in the midphase of the ICG angiogram.

CONCLUSIONS

External radiation exposure may lead to both retinal and choroidal alterations which may be independent events and which may manifest after a long period of quiescence. Furthermore, ICG angiography appears to be a useful diagnostic tool to study the alterations of the choroid following external eye irradiation.

The beginning of using X-rays and the evolution of equipment for the treatment of ocular cancer

Until the early 20^thcentury enucleation of the eyeball or its partial excision were the basic treatments for ocular cancer. The discovery of X-rays by Wilhelm Conrad Röntgen (1845-1923) offered new possibilities to the treatment of ocular cancer either as mono or as adjuvant therapy. Nowdays this treatment is more sophisticated.

Comparison between beta radiation dose distribution due to LDR and HDR ocular brachytherapy applicators using GATE Monte Carlo platform

Eye applicators with 90Sr/90Y and 106Ru/106Rh beta-ray sources are generally used in brachytherapy for the treatment of eye diseases as uveal melanoma. Whenever, radiation is used in treatment, dosimetry is essential. However, knowledge of the exact dose distribution is a critical decision-making to the outcome of the treatment. The Monte Carlo technique provides a powerful tool for calculation of the dose and dose distributions which helps to predict and determine the doses from different shapes of various types of eye applicators more accurately. The aim of this work consisted in using the Monte Carlo GATE platform to calculate the 3D dose distribution on a mathematical model of the human eye according to international recommendations. Mathematical models were developed for four ophthalmic applicators, two HDR 90Sr applicators SIA.20 and SIA.6, and two LDR 106Ru applicators, a concave CCB model and a flat CCB model. In present work, considering a heterogeneous eye phantom and the chosen tumor, obtained results with the use of GATE for mean doses distributions in a phantom and according to international recommendations show a discrepancy with respect to those specified by the manufacturers. The QC of dosimetric parameters shows that contrarily to the other applicators, the SIA.20 applicator is consistent with recommendations. The GATE platform show that the SIA.20 applicator present better results, namely the dose delivered to critical structures were lower compared to those obtained for the other applicators, and the SIA.6 applicator, simulated with MCNPX generates higher lens doses than those generated by GATE.

[Possibility of 3D Printing in Ophthalmology - First Experiences by Stereotactic Radiosurgery Planning Scheme of Intraocular Tumor]

Nowadays 3D printing allows us to create physical objects on the basis of digital data. Thanks to its rapid development the use enormously increased in medicine too. Its creations facilitate surgical planning processes, education and research in context of organ transplantation, individualization prostheses, breast forms, and others.Our article describes the wide range of applied 3D printing technology possibilities in ophthalmology. It is focusing on innovative implementation of eye tumors treatment planning in stereotactic radiosurgery irradiation.We analyze our first experience with 3D printing model of the eye in intraocular tumor planning stereotactic radiosurgery.

KEY WORDS

3D printing, model, Fused Deposition Modelling, stereotactic radiosurgery, prostheses, intraocular tumor.

Isolated Ocular Relapse in Childhood Acute Lymphoblastic Leukemia during Second Interim Maintenance Phase of Chemotherapy: Case Report

More than 80% of acute lymphoblastic leukemia (ALL) in pediatric population is curable by using combinations of chemotherapy. However, 20% of the cases still suffer from disease relapse. The most common site of relapse is bone marrow. Relapse of childhood ALL involving the eyeball is rare. However, it occurs in 2.2% of relapsing children. The authors described a 10-year-old Thai boy with underlying ALL on therapy, presented with a one-month history of progressive visual loss of his right eye. The clinical and imaging studies strongly suggested the diagnosis of isolated ocular relapse. In this report, the authors presented the findings from successfully specific treatment consisting of systemic chemotherapy and radiation therapy on the affected eye. From other studies, the outcome was more favorable in cases of ocular relapse off therapy. In our study, one case of isolated ocular relapse ALL was reported.

Treatment Outcome of Radiotherapy for Localized Primary Ocular Adnexal MALT Lymphoma--Prognostic Effect of the AJCC Tumor-Node-Metastasis Clinical Staging System

AIM

To analyze the treatment outcome of radiotherapy for localized primary ocular adnexal mucosa-associated lymphoid tissue lymphoma (POAML) and evaluate the prognostic effect of the American Joint Committee on Cancer (AJCC) tumor-node-metastasis (TNM) clinical staging system for POAML.

PATIENTS AND METHODS

Seventy-three patients with Ann Arbor stage IE POAML who were treated with radiotherapy alone were analyzed. T-Factor based on the AJCC staging system was T1 in 28, T2 in 33 and T3 in 12 patients.

RESULTS

Out of nine patients with relapse, six had distant and three had contralateral ocular adnexal relapse. One patient died of lymphoma progression. The 5-year local control and progression-free survival (PFS) rates were 100% and 81.5%, respectively. T-Factor was not significantly associated with PFS.

CONCLUSION

Radiotherapy achieved excellent local control and survival rates for stage IE POAML. The AJCC TNM clinical staging system was not significantly predictive for PFS of stage IE POAML.

Secondary neutron doses in proton therapy treatments of ocular melanoma and craniopharyngioma

Monte Carlo simulations were used to assess secondary neutron doses received by patients treated with proton therapy for ocular melanoma and craniopharyngioma. MCNPX calculations of out-of-field doses were done for ∼20 different organs considering realistic treatment plans and using computational phantoms representative of an adult male individual. Simulations showed higher secondary neutron doses for intracranial treatments, ∼14 mGy to the salivary glands, when compared with ocular treatments, ∼0.6 mGy to the non-treated eye. This secondary dose increase is mainly due to the higher proton beam energy (178 vs. 75 MeV) as well as to the impact of the different beam parameters (modulation, collimation, field size etc.). Moreover, when compared with published data, the assessed secondary neutron doses showed similar trends, but sometimes with sensitive differences. This confirms secondary neutrons to be directly dependent on beam energy, modulation technique, treatment configuration and methodology.

Diagnosis and treatment of a periocular myxosarcoma in a bearded dragon (Pogona vitticeps)

A 5-year-old male Australian bearded dragon (Pogona vitticeps) was presented with a 2-month history of a periocular mass. The clinical evaluation included a physical examination, hematology, biochemistry, and radiographs. The mass was treated surgically and diagnosed as myxosarcoma. Strontium-90 plesiotherapy was attempted, but the mass recurred 5 mo later.

Radiotherapy for early-stage primary ocular adnexal mucosa-associated lymphoid tissue lymphoma

BACKGROUND

Primary ocular adnexal mucosa-associated lymphoid tissue lymphoma (POAML) is a rare disease. The purpose of this study was to evaluate the treatment outcome and patterns of failure of patients with early-stage POAML treated with radiotherapy.

PATIENTS AND METHODS

From 1995 to 2008, 53 patients with early-stage POAML were reviewed. Tumors were categorized as either superficial or mass-forming type. In principle, superficial lesions (n=11) were treated with 24 Gy, while the mass-forming lesions (n=42) were irradiated with 30 Gy. The median follow-up period was 3.9 years.

RESULTS

All four cases of relapse had mass-forming lesions. The 5-year overall and progression-free survival rates were 100% and 91.5%, respectively. Although 30 patients experienced grade 2 or 3 late adverse events, no patients had radiation-related retinopathy.

CONCLUSION

Early-stage POAML can be well-controlled with radiotherapy. However, the risk of distant relapse should be noted, in particular, for mass-forming tumors.

Radiation therapy: orbital tumors

Orbital tumors are rare overall, comprising 0.1% of all tumors and less than 20% of all orbital diseases. Tumors may be benign, locally aggressive, or malignant. Of the malignant tumors, lymphomas and metastases are the most common and are primarily seen in the elderly population. While surgery and chemotherapeutic agents are often employed in the management of these lesions, not all patients are candidates for these therapies. Radiation therapy offers a noninvasive, well-tolerated primary treatment modality, whereby vision-sparing is feasible in many cases. In this chapter, we review an array of non-neoplastic entities and orbital tumors, for which there exists a role for radiation, and the radiotherapeutic techniques and applications in their management.

Metastasis inhibition after proton beam, β- and γ-irradiation of melanoma growing in the hamster eye

Standard ocular tumor treatment includes brachytherapy, as well as proton therapy, particularly for large melanoma tumors. However, the effects of different radiation types on the metastatic spread is not clear. We aimed at comparing ruthenium ((106)Ru, emitting β electrons) and iodine ((125)I, γ-radiation) brachytherapy and proton beam therapy of melanoma implanted into the hamster eye on development of spontaneous lung metastases. Tumors of Bomirski Hamster Melanoma (BHM) implanted into the anterior chamber of the hamster eye grew aggressively and completely filled the anterior chamber within 8-10 days. Metastases, mainly in the lung, were found in 100% of untreated animals 30 days after enucleation. Tumors were irradiated at a dose of 3-10 Gy with a (106)Ru plaque and at a dose of 6-14 Gy using a (125)I plaque. The protons were accelerated using the AIC-144 isochronous cyclotron operating at 60 MeV. BHM tumors located in the anterior chamber of the eye were irradiated with 10 Gy, for the depth of 3.88 mm. All radiation types caused inhibition of tumor growth by about 10 days. An increase in the number of metastases was observed for 3 Gy of β-irradiation, whereas at 10 Gy an inhibition of metastasis was found. γ-radiation reduced the metastatic mass at all applied doses, and proton beam therapy at 10 Gy also inhibited the metastastic spread. These results are discussed in the context of recent clinical and molecular data on radiation effects on metastasis.

Primary intraocular central nervous system lymphoma masquerading as diffuse retinal vasculitis

A 49-year-old woman had blurred vision and floaters of 4 days duration in the right eye. Ocular examination revealed granulomatous panuveitis, vitritis and diffuse retinal vasculitis. Following a strongly positive tuberculin skin test, she received antitubercular therapy with oral steroids and immunosuppressants. A year later, despite therapy, vitritis and vasculitis persisted. Additionally, yellowish white lesions appeared beneath the retinal pigment epithelium. Fluorescein angiography revealed a leopard skin appearance. Following a negative vitreous biopsy, she was subjected to a chorioretinal biopsy which revealed non-Hodgkin's lymphoma. MRI was normal. The ocular lesions resolved following intravitreal methotrexate injections. MRI of the brain was repeated every 3 months to rule out central nervous system (CNS) involvement. About 2.5 years after initial presentation, she complained of ataxia, hypersomnia and speech difficulty. MRI of the brain now showed lesions in the thalamocapsular region and the corpus callosum splenium suggestive of CNS lymphoma. She underwent a whole brain radiation with symptomatic improvement followed by chemotherapy.

[Using the superficial temporal fascia flap in orbital surgery]

The superficial temporal fascia flap gives a fine malleable well vascularized tissue and can be used as a pedicled or a free flap to cover large areas of loss of substance. Its dissection needs a period of training. Its use in orbital surgery is rare. However when it is about an anophthalmic socket following radiotherapy with orbital retraction syndrome, it provides tissue of good quality. This could allow later reconstruction by mucous grafts. When used on cavities of exenteration it allows fast re-epithelialisation even post-radiotherapy, while allowing the monitoring of the cavity and in particular the early detection of any tumor recurrence. Its use is advantageous in unfavorable conditions especially after radiotherapy.

Lauriston S. Taylor Lecture on radiation protection and measurements: what makes particle radiation so effective?

The scientific basis for the physical and biological effectiveness of particle radiations has emerged from many decades of meticulous basic research. A diverse array of biologically relevant consequences at the molecular, cellular, tissue, and organism level have been reported, but what are the key processes and mechanisms that make particle radiation so effective, and what competing processes define dose dependences? Recent studies have shown that individual genotypes control radiation-regulated genes and pathways in response to radiations of varying ionization density. The fact that densely ionizing radiations can affect different gene families than sparsely ionizing radiations, and that the effects are dose- and time-dependent, has opened up new areas of future research. The complex microenvironment of the stroma and the significant contributions of the immune response have added to our understanding of tissue-specific differences across the linear energy transfer (LET) spectrum. The importance of targeted versus nontargeted effects remains a thorny but elusive and important contributor to chronic low dose radiation effects of variable LET that still needs further research. The induction of cancer is also LET-dependent, suggesting different mechanisms of action across the gradient of ionization density. The focus of this 35th Lauriston S. Taylor Lecture is to chronicle the step-by-step acquisition of experimental clues that have refined our understanding of what makes particle radiation so effective, with emphasis on the example of radiation effects on the crystalline lens of the human eye.

Optical eye tracking system for noninvasive and automatic monitoring of eye position and movements in radiotherapy treatments of ocular tumors

A noninvasive eye tracking system based on infrared 3-D video-oculographic techniques is proposed for the automatic monitoring of eye position and orientation in external beam radiotherapy of ocular tumors. The presented method can be applied for the real-time estimation of lesion position and tumor-beam misalignments, allowing automatic patient setup and eye movement gated treatments. A prototypal eye tracker was developed and tested on five subjects, achieving gaze estimation errors of 0.5° and eye monitoring frequencies of 125 Hz. The proposed application can potentially improve quality and efficacy of ocular radiotherapy treatments, currently based on invasive, qualitative, and manual control procedures.

A Tandetron™ as proton injector for the eye tumor therapy in Berlin

The therapy of eye tumors with fast protons is an excellent tool giving very high local control rates. At the Helmholtz-Zentrum Berlin (HZB) almost 1800 patients were treated since 1998. A 2 MV Tandetron™ was installed as injector for the k = 132 HZB cyclotron. Using the standard 358 duoplasmatron ion source with direct extraction of negative hydrogen ions an extremely stable proton beam can be delivered, both on the short-term and the long-term scale. The hair-needle filaments made from thoriated tungsten wires have safe operation times of more than 1000 h.

Undifferentiated carcinoma of the lacrimal sac: case report and review of literature

A 55-year-old man presented with a 2-year history of right-sided epiphora and was referred to the Oculoplastic services for dacryocystorhinostomy. A 3-month progressive growth of a right medial canthal mass was found. MRI revealed an extraconal, lobulated, homogeneously enhancing mass in the lacrimal sac fossa with globe indentation and displacement supero-temporally. Following a transcanalicular needle biopsy which was suggestive of a carcinoma, he underwent medial orbitectomy and maxillectomy, through a lateral rhinotomy, with removal of puncta and canaliculi after ensuring no regional or systemic spread. The lacrimal sac tumor was encapsulated, extending superiorly above the medial canthal tendon and involving the nasolacrimal duct, and posteriorly along the medial orbital wall. After ensuring surgical margins were cleared of tumor infiltration, orbital reconstruction was performed with titanium plate and nasolabial flap. He has completed adjuvant radiotherapy with no evidence of tumor recurrence at 15 months of follow-up.

[A case of intraocular lymphoma having retinal adverse events associated with intravitreal methotrexate]

BACKGROUND

We report a case of intraocular lymphoma that developed macular edema and cotton wool spots after treatment with intravitreal methotrexate.

CASE

A 56-year-old woman presented with blurred vision OU. Twelve months prior, she had been diagnosed with primary central nervous system lymphoma. She was in remission after high-dose methotrexate therapy and whole brain radiation therapy. Fundus examination demonstrated bilateral vitreous opacities and subretinal lesions and she was diagnosed with intraocular lymphoma by vitreous biopsy. After treatment with intavitreal methotrexate the subretinal lesions disappeared, but corneal epitheliopathy, macular edema, and cotton wool spots appeared in both eyes. After stopping the intravitreal methotrexate, the corneal epitheliopathy resolved rapidly, but the macular edema and cotton-wool spots remained. These findings disappeared gradually after a posterior sub-Tenon injection of triamcinolone acetonide. Although there was no recurrence of the intraocular lymphoma for 16 months, the patient died from a relapse of the central nervous system lymphoma.

CONCLUSIONS

The use of intravitreal methotrexate after radiation therapy may be associated with adverse events in the retina, including possible radiation retinopathy.

Microdosimetric assessment of the radiation quality of a therapeutic proton beam: comparison between numerical simulation and experimental measurements

Using protons for the treatment of ocular melanoma (especially of posterior pole tumours), the radiation quality of the beam must be precisely assessed to preserve the vision and to minimise the damage to healthy tissue. The radiation quality of a therapeutic proton beam at the Centre Antoine Lacassagne in Nice (France) was measured using microdosimetric techniques, i.e. a miniaturised version of a tissue-equivalent proportional counter. Measurements were performed in a 1-µm site at different depths in a Lucite phantom. Experimental data showed a significant increase in the beam quality at the distal edge of the spread-out Bragg peak (SOBP). In this paper, the numerical simulation of the experimental setup is done with the FLUKA Monte Carlo radiation transport code. The calculated microdosimetric spectra are compared with the measured ones at different depths in tissue for a monoenergetic proton beam (E=62 MeV) and for a modulated SOBP. Numerically and experimentally predicted relative biological effectiveness values are in good agreement. The calculated frequency-averaged and dose-averaged lineal energy mean values are consistent with measured data.

Diagnosis and management of mucoepidermoid carcinoma of the lacrimal duct

Primary tumors of the lacrimal sac are rare, and mucoepidermoid carcinomas of the lacrimal sac have only been reported 13 times in the literature. We reported an intermediate-grade mucoepidermoid carcinoma that was managed with wide local excision, medial maxillectomy, and external beam radiotherapy, and the patient has remained disease-free for 7 years. Orbital exenteration had generally been recommended for these tumors, but newer, more conservative resections along with radiation therapy may be equally effective.

Current treatments for radiation retinopathy

BACKGROUND

to review the currently available therapeutic modalities for radiation retinopathy (RR), including newer investigational interventions directed towards specific aspects of the pathophysiology of this refractory complication.

METHODS

a review of the literature encompassing the pathogenesis of RR and the current therapeutic modalities available was performed.

RESULTS

RR is a chronic and progressive condition that results from exposure to any source of radiation. It might be secondary to radiation treatment of intraocular tumors such as choroidal melanomas, retinoblastomas, and choroidal metastasis, or from unavoidable exposure to excessive radiation from the treatment of extraocular tumors like cephalic, nasopharyngeal, orbital, and paranasal malignancies. After the results of the Collaborative Ocular Melanoma Study, most of the choroidal melanomas are being treated with plaque brachytherapy increasing by that the incidence of this radiation complication. RR has been reported to occur in as many as 60% of eyes treated with plaque radiation, with higher rates associated with larger tumors. Initially, the condition manifests as a radiation vasculopathy clinically seen as microaneurysms and telangiectases, with posterior development of retinal hard exudates and hemorrhages, macular edema, neovascularization and tractional retinal detachment. Regrettably, the management of these eyes remains limited. Photodynamic therapy, laser photocoagulation, oral pentoxyphylline and hyperbaric oxygen have been attempted as treatment modalities with inconclusive results. Intravitreal injections of anti-vascular endothelial growth factor such as bevacizumab, ranibizumab and pegaptanib sodium have been recently used, also with variable results.

DISCUSSION

RR is a common vision threatening complication following radiation therapy. The available therapeutic options are limited and show unsatisfactory results. Further large investigative studies are required for developing better therapeutic as well as preventive treatment strategies.

Angiogenesis and vascular endothelial growth factors in intraocular tumors

The role of angiogenesis in tumors appears obvious: without vessels, tumors cannot grow. However, the long-held belief that all human solid tumors are angiogenesis-dependent has been challenged by the universally disappointing results of anti-angiogenesis therapy in cancer. This may be explained by the fact that cooption of preexisting vasculature as a primary or secondary mechanism of tumor vascularization is more important than previously thought. Nevertheless, anti-angiogenesis therapy may play an important (adjuvant) role in the prevention of metastases of intraocular tumors (uveal melanoma and retinoblastoma). Antivascular endothelial growth factor therapy already plays an important role in the management of irradiation complications in tumor eyes.

The potential of proton beam radiation therapy in intracranial and ocular tumours

A group of oncologists and hospital physicists have estimated the number of patients in Sweden suitable for proton beam therapy. The estimations have been based on current statistics of tumour incidence, number of patients potentially eligible for radiation treatment, scientific support from clinical trials and model dose planning studies and knowledge of the dose-response relations of different tumours and normal tissues. In intracranial benign and malignant tumours, it is estimated that between 130 and 180 patients each year are candidates for proton beam therapy. Of these, between 50 and 75 patients have malignant glioma, 30-40 meningeoma, 20-25 arteriovenous malformations, 20-25 skull base tumours and 10-15 pituitary adenoma. In addition, 15 patients with ocular melanoma are candidates.

Primary Intraocular Lymphoma: A Review

Primary intraocular lymphoma (PIOL) is a type of primary central nervous system lymphoma (PCNSL). It is the most common neoplastic masquerade syndrome involving the eye. Its protean ocular manifestations, plus in many cases the initial positive response to corticosteroid therapy for presumed uveitis, delay accurate diagnosis. A high index of suspicion is essential, followed by tissue biopsy with cytology and ancillary studies. Current treatment is based on chemotherapy featuring high-dose methotrexate and radiation therapy. Prognosis is poor due to CNS involvement, but newer therapies have had some success in prolonging survival.

Experimental studies of photodynamic therapy in a retinoblastoma-like tumour

Combination therapy with a purified hematoporphyrin derivative, Photofrin II, and red light (photodynamic therapy) was investigated in a retinoblastoma-like tumour growing in the eyes of rats in vivo and in cell cultures. There was a marked dose-response relationship between Photofrin II and the light energy both in vitro and in vivo. Up to 33% of the tumours could be controlled in vivo. In vivo/in vitro assays indicated Photofrin II uptake in the tumour cells in vivo in relation to the administered doses. Studies of cell death kinetics suggested that the mechanisms of photodynamic therapy were both a primary cell kill effect and a secondary tissue destruction, probably as a consequence of vascular damage.