Gamma Knife Stereotactic Radiosurgery Research Articles

Mean Brain Dose Remains Uninfluenced by the Lesion Number for Gamma Knife Stereotactic Radiosurgery for 10+ Metastases

Gamma Knife (GK) stereotactic radiosurgery (SRS) is increasingly used as an initial treatment for patients with 10 or more brain metastases. However, the clinical and dosimetric consequences of this practice are not well established. We performed a single-institution, retrospective analysis of 30 patients who received Gamma Knife SRS for 10 or more brain metastases in 1 session. We utilized MIM Software to contour the whole brain and accumulated the doses from all treated lesions to determine the mean dose delivered to the whole brain. Patient outcomes were determined from chart review. Our cohort had a median number of 13 treated lesions (range 10-26 lesions) for a total of 427 treated lesions. The mean dose to the whole brain was determined to be 1.8±0.91Gy (range 0.70-3.8Gy). The mean dose to the whole brain did not correlate with the number of treated lesions (Pearson r= 0.23, P= 0.21), but was closely associated with tumor volume (Pearson r= 0.95, P < 0.0001). There were no significant correlations between overall survival and number of lesions or aggregate tumor volume. Fourteen patients (47%) underwent additional SRS sessions and 6 patients (20%) underwent whole-brain radiotherapy with a median of 6.6months (range 3.0-50months) after SRS. Two patients (6.6%) developed grade 2 radionecrosis following SRS beyond earlier whole-brain radiotherapy. The mean dose to the whole brain in patients treated with Gamma Knife SRS for 10 or more brain metastases remained low with an acceptable rate of radionecrosis. This strategy allowed the majority of patients to avoid subsequent whole-brain radiotherapy.

Outcomes using linear accelerator stereotactic radiosurgery for the treatment of trigeminal neuralgia: A single-center, retrospective study.

Background: Linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) treatment of trigeminal neuralgia (TN) may have similar efficacy to Gamma Knife SRS (GK-SRS), but the preponderance of data comes from patients treated with GK-SRS. Our objective was to analyze the outcomes for LINAC-based treatment of TN in patients at our institution.Methods: We retrospectively analyzed data for patients who underwent LINAC-based SRS for TN from 2006 to 2018. Data were collected from the patients’ medical records. Nonparametric statistics were used for the analysis.Results: Of the 41 patients treated with LINAC-based SRS (typically 90 Gy dosed using a 4 mm collimator for one fraction) during that time, follow-up data of >3 weeks post-SRS were available for 32 patients. The median pretreatment Barrow Neurological Institute (BNI) pain score was 5 (range 4–5). The follow-up period ranged from 0.9 to 113.2 months (median 5 months). There was significant improvement in postradiation BNI pain score (P < 0.001), with 23 (72%) patients who improved to a BNI pain score of 1–3. One patient had bothersome hypoesthesia postradiation. Approximately 38% of patients who had initial pain control had recurrence of symptoms (BNI > 3). Survival analysis showed a median time to pain recurrence of 30 months. There was no relationship between prior microvascular decompression (MVD) surgery and change in BNI pain score pre- to posttreatment.Conclusion: The results demonstrate that LINAC-based SRS is an effective means to treat TN. Prior MVD surgery did not affect efficacy of SRS in lowering the BNI score from pre- to posttreatment in this patient cohort.

RONC-18 Radiosurgery for Primary and Metastatic CNS Malignancies in the Pediatric Population

Abstract PURPOSE: The purpose of this study is to describe outcomes after pediatric radiosurgery for malignant CNS lesions. METHODS: Retrospective chart review was performed for 31 pediatric patients treated at a single institution with Gamma Knife stereotactic radiosurgery (SRS) for primary or metastatic CNS malignancies between 2000-2020. RESULTS: 25 patients were treated with SRS for focal recurrences of primary CNS malignancies, 1 patient was treated in the adjuvant setting after initial resection, and 5 patients were treated for brain metastases. Primary CNS histologies included ependymoma (n=14), glioma (n=4), medulloblastoma (n=2), and meningioma (n=2). 65% were WHO grade 3 or 4. 71% of patients had received a prior course of involved-field external beam radiation to the brain to a median dose of 59.4 Gy in 33 fractions. Median age at SRS was 14 years (range 4-21). Radiosurgery was predominantly performed in a single fraction to a median dose of 17 Gy to a total of 42 targets among 29 patients. Two patients underwent fractionated radiosurgery to 30 Gy in 5 fractions for larger lesions. Median follow up after SRS was 44 months. 7 patients (23%) had no evidence of disease after SRS at a median follow up of 39 months. 6 patients (19%) developed local recurrence at the site of their treated lesion at a median of 13 months after SRS. 20 patients (65%) developed recurrent disease in the CNS outside of the radiosurgery field at a median of 11 months after SRS. 4 patients developed toxicity from SRS related to radiation treatment effect, all of which occurred within 1 year of SRS. CONCLUSIONS: SRS for malignant CNS lesions in the pediatric population provides effective local control and is well-tolerated. However, there remains a substantial risk of distant CNS failures given the nature of recurrent or metastatic disease in these patients.

Microsurgery versus stereotactic radiosurgery for small petroclival meningiomas presenting with intractable trigeminal neuropathy: A historical cohort study.

Data on the outcomes of microsurgical resection (SR) and stereotactic gamma knife radiosurgery (GKRS) in patients with trigeminal neuralgia associated with small petrous apex meningiomas are scarce. We conducted this study to evaluate the pain relief, tumor control, and procedure costs following SR and GKRS for small petroclival meningiomas (less than 3 cm in maximal diameter) using real-world data from our center in Egypt. We conducted a retrospective cohort study of 47 patients with small petrous apex meningiomas presenting with intractable trigeminal nerve pain (SR: n = 22 and GKRS: n = 25). Data regarding pain relief on Barrow Neurological Institute (BNI), procedure cost, and tumor control were retrieved and analyzed using appropriate statistical tests. Patients who underwent SR had lower median BNI pain intensity scores compared to those patients who underwent GKRS, and a significantly higher proportion of patients in the SR group had good BNI scores compared to those in GKRS group (P < 0.05); however, the total costs of SR were significantly less than GKRS (30,519$ vs. 92,372$, respectively). Both SR and GKRS provide pain relief and tumor control in patients with trigeminal neuralgia associated with petrous apex meningioma. However, in the present study, SR achieved better pain control and was more affordable than GKRS.

Stereotactic radiosurgery for the treatment of hypoglossal schwannoma: a multi-institutional retrospective study.

Surgical removal has been performed as the first line treatment for symptomatic or enlarging hypoglossal schwannomas (HS). Stereotactic radiosurgery (SRS) offers a minimally invasive approach that may afford long-term tumor control for patients with HS particularly those who refuse or are unfit for surgery. This study evaluates outcomes after SRS performed for both newly diagnosed and residual tumors after incomplete resection. This retrospective, multi-institutional study involved patients treated with adjuvant or primary SRS for HS. The study end-points included local tumor response, clinical outcomes, and procedure-related complications. All the patients had Gamma Knife SRS. The cohort included 12 patients (five females), median age at SRS 49.5years (range, 37-76)]. The median tumor target volume was 5.9 cm3 (range, 0.7-27.23). At median imaging follow-up of 37months (range, 6-153), tumor control was achieved in 11 patients. Tumor enlargement that was managed with surgical resection was noted at the 6-month follow-up in one patient. At median clinical follow-up of 30.5months (range, 6-157), stability, or improvement of all pre-SRS signs and symptoms was noted in nine patients. Two patients experienced worsening of at least one pre-existing symptoms or sign. New-onset trapezius weakness was noted in one patient and tongue atrophy in two patients. Single-fraction SRS appears to be a safe and effective upfront and adjuvant treatment option for HS. SRS may be recommended as an alternative to surgery for patients presenting with HS or as an adjuvant treatment following subtotal resection and at HS recurrence.

Target localization accuracy in frame-based stereotactic radiosurgery: Comparison between MR-only and MR/CT co-registration approaches.

PurposeIn frame‐based Gamma Knife (GK) stereotactic radiosurgery two treatment planning workflows are commonly employed; one based solely on magnetic resonance (MR) images and the other based on magnetic resonance/computed tomography (MR/CT) co‐registered images. In both workflows, target localization accuracy (TLA) can be deteriorated due to MR‐related geometric distortions and/or MR/CT co‐registration uncertainties. In this study, the overall TLA following both clinical workflows is evaluated for cases of multiple brain metastases.MethodsA polymer gel‐filled head phantom, having the Leksell stereotactic headframe attached, was CT‐imaged and irradiated by a GK Perfexion unit. A total of 26 4‐mm shots were delivered at 26 locations directly defined in the Leksell stereotactic space (LSS), inducing adequate contrast in corresponding T2‐weighted (T2w) MR images. Prescribed shot coordinates served as reference locations. An additional MR scan was acquired to implement the “mean image” distortion correction technique. The TLA for each workflow was assessed by comparing the radiation‐induced target locations, identified in MR images, with corresponding reference locations. Using T1w MR and CT images of 15 patients (totaling 81 lesions), TLA in clinical cases was similarly assessed, considering MR‐corrected data as reference. For the MR/CT workflow, both global and region of interest (ROI)‐based MR/CT registration approaches were studied.ResultsIn phantom measurements, the MR‐corrected workflow demonstrated unsurpassed TLA (median offset of 0.2 mm) which deteriorated for MR‐only and MR/CT workflows (median offsets of 0.8 and 0.6 mm, respectively). In real‐patient cases, the MR‐only workflow resulted in offsets that exhibit a significant positive correlation with the distance from the MR isocenter, reaching 1.1 mm (median 0.6 mm). Comparable results were obtained for the MR/CT‐global workflow, although a maximum offset of 1.4 mm was detected. TLA was improved with the MR/CT‐ROI workflow resulting in median/maximum offsets of 0.4 mm/1.1 mm.ConclusionsSubpixel TLA is achievable in all workflows. For the MR/CT workflow, a ROI‐based MR/CT co‐registration approach could considerably increase TLA and should be preferred instead of a global registration.

Recurrent Radiation-Induced Cavernous Malformation After Gamma Knife Stereotactic Radiosurgery for Brain Metastasis

Cavernous malformations are a rare complication of radiation therapy reported most commonly as a late complication after cranial irradiation for pediatric malignancies. However, cavernous malformations after stereotactic radiosurgery in adult patients are not well characterized. We present a case of a 67-year-old female with metastatic breast cancer who received Gamma Knife stereotactic radiosurgery for brain metastases and developed a cavernous malformation at the site of a treated metastasis 30 months after treatment. She underwent resection and did well until 55 months later, when she developed symptomatic recurrence of cavernous malformation without evidence of tumor recurrence, requiring repeat resection. This represents the first reported case of radiation-induced cavernous malformation treated with stereotactic radiosurgery for brain metastases, who later developed a recurrence of the cavernous malformation. As patients with brain metastases are living longer and are increasingly treated with stereotactic radiosurgery, awareness of cavernous malformation as a potential complication and the risk of recurrence is critical to ensure appropriate diagnosis and management.

Clinical Evaluation of the Inverse Planning System Utilized in Gamma Knife Lightning.

ObjectivesThe purpose of this study is to independently compare the performance of the inverse planning algorithm utilized in Gamma Knife (GK) Lightning Treatment Planning System (TPS) to manual forward planning, between experienced and inexperienced users, for different types of targets.Materials and MethodsForty patients treated with GK stereotactic radiosurgery (SRS) for pituitary adenoma (PA), vestibular schwannoma (VS), post-operative brain metastases (pBM), and intact brain metastases (iBM) were randomly selected, ten for each site. Three inversely optimized plans were generated for each case by two experienced planners (OptExp1 and OptExp2) and a novice planner (OptNov) using GK Lightning TPS. For each treatment site, the Gradient Index (GI), the Paddick Conformity Index (PCI), the prescription percentage, the scaled beam-on time (sBOT), the number of shots used, and dosimetric metrics to OARs were compared first between the inversely optimized plans and the manually generated clinical plans, and then among the inversely optimized plans. Statistical analyses were performed using the Student’s t-test and the ANOVA followed by the post-hoc Tukey tests.ResultsThe GI for the inversely optimized plans significantly outperformed the clinical plans for all sites. PCIs were similar between the inversely optimized and clinical plans for PA and VS, but were significantly improved in the inversely optimized plans for iBM and pBM. There were no significant differences in the sBOT between the inversely optimized and clinical plans, except for the PA cases. No significant differences were observed in dosimetric metrics, except for lower brain V12Gy and PTV D98% in the inversely optimized plans for iBM. There were no noticeable differences in plan qualities among the inversely optimized plans created by the novice and experienced planners.ConclusionInverse planning in GK Lightning TPS produces GK SRS plans at least equivalent in plan quality and similar in sBOT compared to manual forward planning in this independent validation study. The automatic workflow of inversed planning ensures a consistent plan quality regardless of a planner’s experience.

Chronic encapsulated expanding hematomas after stereotactic radiosurgery for intracranial arteriovenous malformations.

Cerebral arteriovenous malformations (AVMs) are rare cerebral vascular lesions that are associated with high morbidity and mortality from hemorrhage; however, stereotactic radiosurgery (SRS) is a well-validated treatment modality. Few reports have delineated a subgroup of patients who develop delayed chronic encapsulated expanding hematomas (CEEHs) despite angiographic evidence of AVM obliteration following radiosurgery. In this report, the authors performed a retrospective review of more than 1000 radiosurgically treated intracranial AVM cases to delineate the incidence and management of this rare entity. Between 1988 and 2019, 1010 patients with intracranial AVM underwent Gamma Knife SRS at the University of Pittsburgh Medical Center. In addition to a review of a prospective institutional database, the authors performed a retrospective chart review of the departmental AVM database to specifically identify patients with CEEH. Pertinent clinical and radiological characteristics as well as patient outcomes were recorded and analyzed. Nine hundred fifty patients with intracranial AVM (94%) had sufficient clinical follow-up for analysis. Of these, 6 patients with CEEH underwent delayed resection (incidence rate of 0.0045 event per person-year). These patients included 4 males and 2 females with a mean age of 45.3 ± 13.8 years at the time of initial SRS. Four patients had smaller AVM volumes (4.9-10 cm3), and 3 of them were treated with a single SRS procedure. Two patients had larger-volume AVMs (55 and 56 cm3), and both underwent multimodal management that included staged SRS and embolization. Time to initial recognition of the CEEH after initial SRS ranged between 66 and 243 months. The time between CEEH recognition and resection ranged from 2 to 9 months. Resection was required because of progressive neurological symptoms that correlated with imaging evidence of gradual hematoma expansion. All 6 patients had angiographically confirmed obliteration of their AVM. Pathology revealed a mixed chronicity hematoma with areas of fibrosed blood vessels and rare areas of neovascularization with immature blood vessels but no evidence of a persistent AVM. All 6 patients reported persistent clinical improvement after hematoma resection. CEEH after SRS for AVM is a rare complication with an incidence rate of 0.0045 event per person-year over the authors' 30-year experience. When clinical symptoms progress and imaging reveals progressive enlargement over time, complete resection of a CEEH results in significant clinical recovery. Knowledge of this rare entity facilitates timely detection and eventual surgical intervention to achieve optimal outcomes.

Multi-Session Radiosurgery for Numerous Small Brain Metastases

Objectives: Treatment of multiple brain metastases more than 10 is challenging. Whole brain radiotherapy (WBRT) is generally believed to be the first treatment choice. In order to escape from mental deterioration after WBRT, we have performed Gamma Knife stereotactic radiosurgery (GKS) for numerous small brain metastases. Methods: Twelve cases of numerous (more than 30) brain metastases were treated by GKS. Mean total session number was 5.42 times, ranging 2 to 17. Each tumor was treated with the margin dose between 14 to 20 Gy. The tumor number treated in whole sessions was ranged from 31 to 144 (mean, 70.8). Results: Almost all the irradiated tumors either disappeared or shrank at the patient’s death or at the last follow-up, though new metastatic tumors were subsequently developed in some cases which required an additional treatment with GKS. At the last follow-up (3 to 51 months after GKS), nine cases were alive and well and three were dead. As adverse effects, two cases demonstrated seizures by radiation brain injury and another showed a gait disturbance. No apparent mental deterioration was observed during follow-up. Conclusion: Radiosurgery for numerous small brain metastases may be preferable rather than WBRT. Keywords: Brain, Gamma Knife, metastasis, multiple, stereotactic radiotherapy, stereotactic radiosurgery

Tolerability and Stability of Mask Fixation in Gamma Knife Stereotactic Radiosurgery: Predictors of Treatment Interruptions

Background. Frameless fixation with a thermoplastic mask is an alternative to traditional frame-based immobilization for Gamma-Knife stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT). However, interruptions during beam-on time can significantly prolong treatment delivery, impacting patient experience and unit workflow. Aim. We investigated clinical and technical predictors of treatment interruptions, and the phases of treatment during which interruptions are most likely to occur. Methods. Patients undergoing frameless Gamma Knife SRS or FSRT in 2020 were retrospectively reviewed. Clinical parameters were extracted from electronic medical records. Dosimetric and treatment interruption data were obtained from Gamma Knife treatment reports. Univariate and multivariate analyses analyzed technical and clinical predictors of treatment interruptions. Results. Our cohort included 84 patients receiving 141 fractions encompassing 255 lesions. 49/84 (58.3%) were female, 79/84 (94.0%) had brain metastases, 49/84 (58.3%) were taking dexamethasone and 30/84 (35.7%) used analgesics. 89/106 (84.0%) courses were single fractions. Mean planned beam-on time was 37.1 minutes (range 7.1-118.8 min) versus a total bed time of 64.9 minutes (range 15-252min) per fraction. 64.5% (91/141) of fractions were interrupted at least once; 12/141 fractions were paused 20 times or more, with a maximum 54 pauses. The mean number of pauses per quartile decreased the further the patient proceeded in beam-on time, and patients receiving first lifetime cranial radiation paused more often than during subsequent fractions. At least one pause occurred in 100% of fractions with a planned beam-on time exceeding 60 minutes. Planned beam-on time, number of gating events and high-definition motion management alarms significantly correlated with total number of pauses on multivariate analysis (all p&lt;0.0001); these three factors, along with prep time and number of operator-initiated pauses, predicted total time on the Gamma Knife couch (all p&lt;0.0001). Clinical factors, medication use, and prior SRS/FSRT were not predictive of pauses. Conclusions. Planned beam-on time, number of gating events and high-definition motion management alarms significantly predicted likelihood of interruptions during frameless Gamma Knife SRS/FSRT. These factors should be considered in selection of immobilization method, especially if exceeding 60 minutes.

Diagnosis and Treatment of Patients with Trigeminal Neuralgia: A Review

Trigeminal neuralgia (TN) is one of the most common forms of neuropathic pain found in the head and neck region, the diagnosis of which is clinical. Long-term oral medication offers no benefits for patients with TN. Interventions for these patients include percutaneous rhizotomy, radiofrequency thermocoagulation, balloon compression, botulinum neurotoxin, stereotactic Gamma knife radiosurgery and microvascular decompression. The aim of the present study was to investigate aspects of the diagnosis and treatment of patients with trigeminal neuralgia through a literature review. A bibliographic survey was conducted through searches of the SciELO, BIREME, Medline and Google Scholar electronic databases for relevant articles published in the English language. The articles found in the literature were divided into four groups: Group 1 – definition and epidemiology (references 1 to 9); Group 2 – diagnosis (references 10 to 12), Group 3: treatment (references 13 to 26); Group 4: interventional approaches (references 27 to 40). TN is one of the most common forms of neuropathic pain found in the head and neck region. The diagnosis is based on a history of pain such as an “electrical shock” felt in a division of the trigeminal nerve. Approximately 50% of patients with TN do not achieve long-term benefits from drug therapy. Interventional approaches require more scientific research. Future studies should focus on genetics, unexplored etiological factors, sensory function, neurosurgical outcomes and complications, combinations and neuromodulation as well as the development of new drugs with greater tolerability.

Use of predictive spatial modeling to reveal that primary cancers have distinct central nervous system topography patterns of brain metastasis.

Brain metastasis is the most common intracranial neoplasm. Although anatomical spatial distributions of brain metastasis may vary according to primary cancer subtype, these patterns are not understood and may have major implications for treatment. To test the hypothesis that the spatial distribution of brain metastasis varies according to cancer origin in nonrandom patterns, the authors leveraged spatial 3D coordinate data derived from stereotactic Gamma Knife radiosurgery procedures performed to treat 2106 brain metastases arising from 5 common cancer types (melanoma, lung, breast, renal, and colorectal). Two predictive topographic models (regional brain metastasis echelon model [RBMEM] and brain region susceptibility model [BRSM]) were developed and independently validated. RBMEM assessed the hierarchical distribution of brain metastasis to specific brain regions relative to other primary cancers and showed that distinct regions were relatively susceptible to metastasis, as follows: bilateral temporal/parietal and left frontal lobes were susceptible to lung cancer; right frontal and occipital lobes to melanoma; cerebellum to breast cancer; and brainstem to renal cell carcinoma. BRSM provided probability estimates for each cancer subtype, independent of other subtypes, to metastasize to brain regions, as follows: lung cancer had a propensity to metastasize to bilateral temporal lobes; breast cancer to right cerebellar hemisphere; melanoma to left temporal lobe; renal cell carcinoma to brainstem; and colon cancer to right cerebellar hemisphere. Patient topographic data further revealed that brain metastasis demonstrated distinct spatial patterns when stratified by patient age and tumor volume. These data support the hypothesis that there is a nonuniform spatial distribution of brain metastasis to preferential brain regions that varies according to cancer subtype in patients treated with Gamma Knife radiosurgery. These topographic patterns may be indicative of the abilities of various cancers to adapt to regional neural microenvironments, facilitate colonization, and establish metastasis. Although the brain microenvironment likely modulates selective seeding of metastasis, it remains unknown how the anatomical spatial distribution of brain metastasis varies according to primary cancer subtype and contributes to diagnosis. For the first time, the authors have presented two predictive models to show that brain metastasis, depending on its origin, in fact demonstrates distinct geographic spread within the central nervous system. These findings could be used as a predictive diagnostic tool and could also potentially result in future translational and therapeutic work to disrupt growth of brain metastasis on the basis of anatomical region.

Feasibility Study of Stereotactic Radiosurgery Treatment of Glomus Jugulare Tumors via HyperArc VMAT.

This study aims to report on the clinical validation and feasibility of utilizing a novel fully automated treatment planning and delivery system, HyperArc VMAT stereotactic radiosurgery (SRS) for glomus jugulare tumors (GJT). Independent dose verification of the HyperArc module via the MD Anderson's SRS head phantom irradiation and credentialing results showed compliance with the SRS treatment requirements per IROC MD Anderson's standard. Following the Alliance clinical trial, AAPM, RTOG protocols, and QUANTEC requirements, utilizing selected three-partial arc geometry of HyperArc module on TrueBeam Linac with 6MV-FFF beam, GJT SRS plans were generated for nine previously treated Gamma Knife (GK) radiosurgery patients using advanced Acuros-based algorithm to account for tissue inhomogeneity corrections and frameless immobilization with Q-fix mask and Encompass device insert. HyperArc VMAT produced highly conformal SRS dose distributions to GJT, a steep dose gradient around the GJT, and spared adjacent critical organs including the spinal cord (< 3.0 Gy). Due to faster patient setup and less MLC modulation through the target (average beam-on time, 6.2 minutes), the HyperArc VMAT plan can deliver a single high-dose of 18 Gy to the GJT in less than 15 minutes overall treatment time, significantly improving patient comfort and clinic workflow. Pretreatment portal dosimetry quality assurance results and independent dose verification via Monte Carlo-based physics second check met our clinical SRS protocol's requirements for treatment. Due to the highly conformal dose distribution, rapid dose fall-off, excellent sparing of adjacent critical organs, and highly precise and accurate treatment, clinical implementation of frameless HyperArc VMAT for GJT patients who may not have access to nor tolerate frame-based GK SRS treatment are underway.

RT-1 Treatment results of salvage gamma knife stereotactic radiosurgery and bevacizumab (AVAgamma therapy) for recurrent malignant glioma

Purpose: We report the treatment results of AVAgamma therapy combining gamma knife (GK) and bevacizumab for recurrent malignant glioma. Subjects: From August 2013 to January 2021, 71 patients (Grade 2:8 patients, Grade3:16 patients, Grade 4:47 patients) with recurrent malignant glioma treated with AVAgamma therapy as salvage therapy at the time of relapse after initial treatment. The average age is 55.7 years, with 44 men and 27 women. The tumor volume is 150 ml or less, and KPS is 40% or more as the indication of AVAgamma therapy. When the irradiation volume of the gamma knife was 15 ml or less, the marginal dose was 20 to 26 Gy, and when the irradiation volume was 15 ml or more, the marginal dose was 12 to 15 Gy in two divided doses.The mean therapeutic borderline dose was 24 Gy. Bevacizumab was administered 10 mg / kg or 15 mg / kg 1 to 10 times after GK. Methods: Median progression-free survival (mPFS) from AVAgamma treatment, median survival (mOS), and mOS from initial treatment were examined and compared with mOS in the RPA classification of recurrent glioma. Results: In relapsing glioma RPA classification, NABTT CNC class 2 mOS is 17.2 months, class 3 mOS is 3.8 months, class 5 mOS is 5.6 months, class 6 mOS is 6.4 months, but mOS from AVAgamma therapy is 18 months in class 3, 11 months in class 5, 9 months in class 6. The survival time has been extended in class3, class5, class6. Discussion: By AVAgamma therapy, it was thought that recurrent lesions were locally controlled and life prognosis was prolonged. Conclusion: AVAgamma therapy is thought to prolong the survival of recurrent malignant glioma and play an important role as salvage treatment.

Comparison of iodine-125 plaque brachytherapy and gamma knife stereotactic radiosurgery treatment outcomes for uveal melanoma patients.

To compare the efficacies of iodine-125 brachytherapy (IBT) and gamma knife stereotactic radiosurgery (GKRS) in the treatment of posterior uveal melanoma. The demographic data and tumor characteristics at diagnosis of 201 patients treated with IBT and 52 patients treated with GKRS were recorded. The two treatments were then compared in terms of complications, local control, eye retention, metastasis, and overall survival rate. The median follow-up time was 56months for the GKRS group and 45months for the IBT group (p = 0.167). There were no significant differences in demographic data or tumor characteristics between the groups at diagnosis. Radiation retinopathy, radiation optic neuropathy, and neovascular glaucoma occurred at similar rates in both groups. However, radiation maculopathy and cataracts occurred more frequently in the GKRS group. The number of cases that have developed vision loss (worsening of best-corrected visual acuity on three or more lines on the Snellen chart) was significantly higher in the GKRS group (60%) compared to the IBT group (44%) (p = 0.048). Local control, metastasis, and 5-year overall survival rates were statistically similar in both groups. GKRS can be preferred as an eye-sparing treatment option for posterior uveal melanoma in cases where brachytherapy cannot be used.

Segmentation of vestibular schwannoma from MRI, an open annotated dataset and baseline algorithm

Automatic segmentation of vestibular schwannomas (VS) from magnetic resonance imaging (MRI) could significantly improve clinical workflow and assist patient management. We have previously developed a novel artificial intelligence framework based on a 2.5D convolutional neural network achieving excellent results equivalent to those achieved by an independent human annotator. Here, we provide the first publicly-available annotated imaging dataset of VS by releasing the data and annotations used in our prior work. This collection contains a labelled dataset of 484 MR images collected on 242 consecutive patients with a VS undergoing Gamma Knife Stereotactic Radiosurgery at a single institution. Data includes all segmentations and contours used in treatment planning and details of the administered dose. Implementation of our automated segmentation algorithm uses MONAI, a freely-available open-source framework for deep learning in healthcare imaging. These data will facilitate the development and validation of automated segmentation frameworks for VS and may also be used to develop other multi-modal algorithmic models.

Implementation of MR-Based Synthetic CT for Stereotactic Radiosurgery Dose Calculation

Most Gamma Knife stereotactic radiosurgery (GKRS) procedures have been performed using water-based dose calculation algorithms with magnetic resonance imaging (MRI) only. We present a dose calculation method that can take into account the inhomogeneity effect in routine GKRS treatment planning without CT imaging for every patient.Twenty-five patients who underwent GKRS at our institution with T1- and T2-weighted whole head MRI as well as brain CT images were selected for this study. Two set of synthetic computed tomographies (sCT) were generated from T1 and T2 MRI using cycle consistent generative adversial networks architecture (cGAN). Images from 20 patients were used to train the algorithm. The other 5 sets of data were used for testing and validation. The sCT images generated were evaluated in terms of the preservation of anatomical structures, the Hounsfield unit accuracy and the overall image quality. All sCT images from the 5 test patients were imported into GammaPlan version 11.1 for dosimetric analyses. We performed dose calculations for each test patient using the water-based TMR algorithm and the convolution algorithm with electron densities from the original CT, the T1-based sCT and the T2-based sCT.The main features of the original CT images (skull shape, bone & air inhomogeneity etc.) for the 5 test patients were successfully reproduced in the sCT images. sCT images from the T1-weighted MRI are in general closer to the original CT images compared to the T2-weighted MR images. For the same dose prescription and same shot arrangement, the maximum difference between the treatment shot times from the CT-based convolution calculation and the TMR calculation is 10.2%. The maximum differences between the treatment shot times from the CT-based convolution calculation and the convolution calculations from the sCTs from the T1 and T2 MR images are 2.3% and 3.8%, respectively.sCT images from brain MRI can be used for the inhomogeneity correction in GKRS dose calculation. T1-weighted MRI may work better than T2-weighted MRI for this purpose.F. Li: None. Y. Xu: None. O.D. Lemus: None. T.J. Wang: Research Grant; AbbVie, Merck, RTOG Foundation, Genentech. Honoraria; Elekta, Wolters Kluwer, Cancer Panels, Rutgers, University of Iowa. Consultant; Doximity, Elekta. Advisory Board; Novocure, AstraZeneca. Travel Expenses; AbbVie, Elekta, Novocure. Stock Options; Doximity. M.B. Sisti: None. C. Wuu: None.

Long-Term Quality of Life and Audiometric Outcomes Following Noninvasive Stereotactic Radiosurgery for Acoustic Neuromas

Though microsurgery remains the most common method for management of acoustic neuromas (ANs), stereotactic radiosurgery continues to be a promising alternative. This study assesses long-term quality of life (QOL) outcomes and changes in hearing acuity in patents who have undergone single fraction Gamma Knife stereotactic radiosurgery (GKSRS) for AN.Prospective QOL outcomes were collected and analyzed to include Hearing Handicap Inventory (HHI), Dizziness Handicap Inventory (DHI), Tinnitus Handicap Inventory (THI), and 36-Item Short-Form Survey (SF-36) scores. Likewise, audiometric outcomes including speech discrimination (SD) and pure-tone average (PTA) were assessed. These data points were collected prior to and following GKSRS at regular intervals up to 5 years post-treatment. A mixed effects model for repeated measures was employed to assess QOL data for statistical significance.A total of 235 patients underwent GKSRS for AN at our institution from January 2007 to January 2017. Of these, 130 patients had available QOL and audiometric follow-up data and were included in this study. Median age was 60 y and median follow-up time was 36 mo. Median tumor size was 1.6 cm (0.1 - 3.6 cm), with median tumor volume of 0.552 cm3 (0.028 - 11.31 cm3), while median cochlear mean dose was 2.4 Gy (0 - 9.7 Gy). Baseline mean (median) HHI, DHI, THI, and SF-36 scores were 31.7 (28), 19.3 (12), 18.2 (12), and 70.0 (73.4) respectively. For each of these QOL metrics, mixed effects analysis indicated no statistically significant decline at any time point out to 5 years post-treatment. Indeed, 87% of patients had baseline SD and PTA scores available; 70% had follow-up SD and PTA available. Of these, 59% had baseline serviceable hearing (Gardner-Robertson score of I or II). Serviceable hearing was preserved in 71% of patients at 1 month, 79% at 6 months, 79% at 12 months, 62% at 18 months, 67% at 24 months, and 68% at 36 months.GKSRS provides long-term maintenance of QOL in the treatment of AN. HHI, DHI, THI, and SF-36 scores showed no significant decline up to 5 years post-radiosurgery. Patients with baseline serviceable hearing exhibited adequate hearing preservation.J.S. Lee: None. K.C. Lee: Royalty; Regents of the University of Michigan. Patent/License Fees/Copyright; Regents of the University of Michigan. D. Bojrab: None. P.Y. Chen: Stock; Greater Michigan Gamma Knife (GMGK). J. Jacob: None. I.S. Grills: Greater Michigan Gamma Knife.

Результаты хирургии катаракты у детей с ретинобластомой

Purpose. To present results of cataract surgery in children with retinoblastoma. Material and methods. Within the period from 2012 to 2020, cataract surgery was performed in 21 children (22 eyes) with retinoblastoma aged 28 to 155 months (average – 65 months). Tumors of group B occurred in 2 cases, group C – in 4, group D – in 14, group E – in 1. In 8 cases, cataract occurred in a single eye. Posterior capsular cataract was observed in 18 patients, total – in 3. In all cases, the presence of cataract impeded the control of the tumor. Before cataract surgery all children underwent systemic chemotherapy, some of them also underwent intra-arterial and/or intravitreal chemotherapy, external beam radiotherapy, Gamma Knife stereotactic radiosurgery and local treatment modalities (episcleral plaque brachytherapy, thermotherapy, cryotherapy). There were no signs of tumor progression in all cases at the time of cataract surgery. The mean interval between complete tumor regression and cataract surgery was 23 months (range 6–75 months). Results. Full transparency of optical media was achieved in all eyes after surgery. No intraoperative and postoperative complications occurred. The final visual acuity was improved in 12 eyes, in the rest visual acuity could not be determined due to age. There were no signs of tumor recurrence or metastases in mean follow-up after surgery of 29 months (range 3–60). Conclusion. Our experience of cataract surgery in children with complete regression of retinoblastoma was proved to be a safe and effective way to improve visual functions and achieve transparency of optical media. Key words: retinoblastoma, cataract surgery, ophtalmooncology, functional results