Long-Term Outcomes of Gamma Knife Radiosurgery for Cerebral Cavernous Malformations: 10 Years and Beyond.

Background: We aimed to evaluate long-term outcomes of gamma knife radiosurgery (GKS) for cerebral cavernous malformations (CCMs).

Methods: Among the 233 CCM patients who underwent GKS, 79 adult patients (96 lesions) followed for over 10 years were included and analyzed retrospectively. Annual hemorrhage rate (AHR) was analyzed the entire cohort of 233 patients and the subset of 79 enrolled patients by dividing lesions into overall CCM lesions and brainstem lesions.

Long-Term Outcome of Unilateral Acoustic Neuromas With or Without Hearing Loss: Over 10 Years and Beyond After Gamma Knife Radiosurgery.

Background: Since the long-term outcomes of 162 patients who underwent gamma knife radiosurgery (GKS) as an initial or adjuvant treatment for acoustic neuromas (ANs) with unilateral hearing loss were first reported in 1998, there has been no report of a comprehensive analysis of what has changed in GKS practice.

Methods: We performed a retrospective study of the long-term outcomes of 106 patients with unilateral sporadic ANs who underwent GKS as an initial treatment. The mean patient age was 50 years, and the mean initial tumor volume was 3.

A 3-month survival model after Gamma Knife surgery in patients with brain metastasis from lung cancer with Karnofsky performance status ≤ 70.

Gamma Knife surgery (GKS) for brain metastasis (BM) has been generally advocated for patients with a Karnofsky performance status (KPS) scale of ≥ 70. However, some patients with a poor KPS scale of < 70 are recoverable after GKS and show durable survival. A purpose of this study is to devise a 3-month survival prediction model to screen patients with BM with a KPS of ≤ 70 in whom GKS is needed.

Consistency of dose rates after applying machine-specific reference correction factors for the gamma knife 16 mm collimator field.

Background: The machine-specific reference (msr) correction factors ( ) were introduced in International Atomic Energy Agency (IAEA) Technical Report Series 483 (TRS-483) for reference dosimetry of small fields. Several correction factor sets exist for a Leksell Gamma Knife (GK) Perfexion or Icon. Nevertheless, experiments have not rigorously validated the correction factors from different studies.

Optimal mask fixation method for frameless radiosurgery with Leksell Gamma Knife Icon.

The Leksell Gamma Knife (LGK) Icon is used for mask-based and frame-based fixation. The mask fixation provides a noninvasive method. However, an optimal mask fixation method is yet to be established.

Preliminary Study on Natural Killer Cell Activity for Interferon-Gamma Production after Gamma Knife Radiosurgery for Brain Tumors.

Objective: High-dose radiation is well known to induce and modulate the immune system. This study was performed to evaluate the correlation between clinical outcomes and changes in natural killer cell activity (NKA) after Gamma Knife Radiosurgery (GKS) in patients with brain cancer.

Methods: We performed an open-label, prospective, cross-sectional study of 38 patients who were treated with GKS for brain tumors, including metastatic and benign brain tumors.

A multivariate approach to determine electron beam parameters for a Monte Carlo 6 MV Linac model: Statistical and machine learning methods.

Purpose: This study aimed to determine the optimal initial electron beam parameters of a Linac for radiotherapy with a multivariate approach using statistical and machine-learning tools.

Methods: For MC beam commissioning, a 6 MV Varian Clinac was simulated using the Geant4 toolkit. The authors investigated the relations between simulated dose distribution and initial electron beam parameters, namely, mean energy (E), energy spread (ES), and radial beam size (RS).

Dosimetric parameters associated with the long-term oncological outcomes of Gamma Knife surgery for sellar and parasellar tumors in pediatric patients.

Objective: The authors aimed to investigate the dosimetric parameter and the minimally required dose associated with long-term control of sellar and parasellar tumors after Gamma Knife surgery (GKS) in children.

Methods: A retrospective analysis was performed on pediatric patients younger than 19 years of age who were diagnosed with sellar and parasellar tumors and received GKS at the authors' institution from 1998 to 2019. Cox proportional hazards regression analyses were used to investigate the dosimetric parameters associated with treatment outcome.

Treatment Planning Factors Associated with Long-Term Outcomes of Gamma Knife Surgery in Patients with Trigeminal Neuralgia.

Objective: Gamma Knife surgery (GKS) is an established treatment option for trigeminal neuralgia (TN). However, the long-term efficacy of GKS for patients with TN has not been well studied. The aim of the study is to evaluate the sequential course of pain control after GKS and analyze the factors associated with the long-term analgesic effect, focusing on radiation dosimetry and neurovascular conflict (NVC) factors.

Development of an IAEA phase-space dataset for the Leksell Gamma Knife Perfexion™ using multi-threaded Geant4 simulations.

This study was conducted to develop a phase-space dataset in the International Atomic Energy Agency (IAEA) format for Monte Carlo (MC) simulations of the Leksell Gamma Knife (LGK, Elekta Instrument AB, Stockholm, Sweden) Perfexion™ (PFX). An open-source MC code, namely, the Geant4 toolkit with a recently updated multi-threaded mode, was used to maximize the efficiency of the developed IAEA phase-space dataset. The absorbed dose profiles for single shots of the LGK PFX were calculated using the developed dataset and compared with those from radiochromic film measurements and Leksell GammaPlan version 11.

Single-Session versus Multisession Gamma Knife Radiosurgery for Large Brain Metastases from Non-Small Cell Lung Cancer: A Retrospective Analysis.

Purpose: To evaluate the efficacy of Gamma Knife radiosurgery (GKS) in patients with large brain metastases by comparing single-session radiosurgery (S-GKS) and multisession radiosurgery (M-GKS), we retrospectively analyzed the clinical outcomes of patients who underwent GKS for brain metastases from non-small cell lung cancer (NSCLC).

Materials And Methods: Between January 2010 and December 2016, 66 patients with 74 lesions ≥10 cm3 from large brain metastases from only NSCLC were included. Fifty-five patients with 60 lesions were treated with S-GKS; 11 patients with 14 lesions were treated with M-GKS.

Petroclival meningiomas: long-term outcomes of multimodal treatments and management strategies based on 30 years of experience at a single institution.

Objective: A thorough investigation of the long-term outcomes and chronological changes of multimodal treatments for petroclival meningiomas is required to establish optimal management strategies. The authors retrospectively reviewed the long-term clinical outcomes of patients with petroclival meningioma according to various treatments, including various surgical approaches, and they suggest treatment strategies based on 30 years of experience at a single institution.

Methods: Ninety-two patients with petroclival meningiomas were treated surgically at the authors' institution from 1986 to 2015.

Frameless Fractionated Gamma Knife Radiosurgery with ICON™ for Large Metastatic Brain Tumors.

Background: Recently, a new generation of gamma knife radiosurgery (GKRS) equipped with a frameless immobilization system has encouraged the use of fractionated GKRS as an increasingly favorable treatment option. We investigated the preliminary outcome of efficacy and toxicity associated with frameless fractionated gamma knife radiosurgery (FF GKRS) for the treatment of large metastatic brain tumors.

Methods: Fifteen patients with 17 lesions were treated using FF GKRS and included in this study, because of the large tumor size of more than 10 cm.

Development of a PMMA phantom as a practical alternative for quality control of gamma knife® dosimetry.

Background: To measure the absorbed dose rate to water and penumbra of a Gamma Knife® (GK) using a polymethyl metacrylate (PMMA) phantom.

Methods: A multi-purpose PMMA phantom was developed to measure the absorbed dose rate to water and the dose distribution of a GK. The phantom consists of a hemispherical outer phantom, one exchangeable cylindrical chamber-hosting inner phantom, and two film-hosting inner phantoms.

Fractionated Gamma Knife Radiosurgery as Initial Treatment for Large Skull Base Meningioma.

We present our experience on the hypofractionated Gamma Knife radiosurgery (FGKS) for large skull base meningioma as an initial treatment. We retrospectively reviewed 23 patients with large skull base meningioma ≥10 cm who underwent FGKS as the initial treatment option. The mean volume of tumors prior to radiosurgery was 21.

Optimal strategy of gamma knife radiosurgery for craniopharyngiomas.

Object: To analyze the outcomes of gamma knife radiosurgery (GKS) for craniopharyngiomas and elucidate the optimal strategy.

Methods: Between 1998 and 2016, 35 patients underwent GKS for the treatment of 40 recurrent or residual craniopharyngiomas. Among 40 GKSs, 22 procedures were single-session GKSs and 18 procedures were fractionated GKSs.

Independent dose validation system for Gamma Knife radiosurgery, using a DICOM-RT interface and Geant4.

Leksell GammaPlan was specifically designed for Gamma Knife (GK) radiosurgery planning, but it has limited accuracy for estimating the dose distribution in inhomogeneous areas, such as the embolization of arteriovenous malformations. We aimed to develop an independent patient dose validation system based on a patient-specific model, constructed using a DICOM-RT interface and the Geant4 toolkit. Leksell Gamma Knife Perfexion was designed in Geant4.

Long-Term Outcome of Gamma Knife Radiosurgery for Symptomatic Brainstem Cavernous Malformation.

Objective: We sought to analyze the long-term outcome of Gamma Knife radiosurgery (GKS) for symptomatic brainstem cavernous malformation (s-BSCM).

Methods: Forty-five patients (14 males, 31 females) were treated with GKS for s-BSCM from January 1998 to December 2011. All patients were followed up for >5 years, and their clinical data were analyzed retrospectively.

Assessment of the accuracy and stability of frameless gamma knife radiosurgery.

The aim of this study was to assess the accuracy and stability of frameless gamma knife radiosurgery (GKRS). The accuracies of the radiation isocenter and patient couch movement were evaluated by film dosimetry with a half-year cycle. Radiation isocenter assessment with a diode detector and cone-beam computed tomography (CBCT) image accuracy tests were performed daily with a vendor-provided tool for one and a half years after installation.

A Retrospective Analysis of the Outcomes of Dural Arteriovenous Fistulas Treated with Gamma Knife Radiosurgery: A Single-Institution Experience.

Background: Gamma knife radiosurgery (GKRS) has recently been used as a treatment modality for dural arteriovenous fistula (DAVF).

Objective: To retrospectively analyze the outcomes of GKRS for DAVF at a single institute.

Methods: Between 1998 and 2016, a total of 20 patients underwent GKRS for DAVF.

Long-Term Outcomes After Gamma Knife Radiosurgery for Benign Meningioma: A Single Institution's Experience With 424 Patients.

Background: Gamma knife radiosurgery (GKRS) is recognized as an important treatment modality for meningioma.

Objective: To analyze the long-term outcomes in meningioma patients treated with GKRS to determine the risk factors related to treatment failure and peritumoral edema (PTE) development.

Methods: Between 1998 and 2010, 770 consecutive patients were treated with GKRS for intracranial meningioma.

Assessment of image co-registration accuracy for frameless gamma knife surgery.

Image co-registration is used in frameless gamma knife radiosurgery (GKSRS) to assign a stereotactic coordinate system and verify patient setup before irradiation. The accuracy of co-registration with cone beam computed tomography (CBCT) images of a Gamma Knife IconTM (GK Icon) was assessed, and the effects of the region of co-registration (ROC) were studied. CBCT-to-CBCT co-registration is used for patient setup verification, and its accuracy was examined by co-registering CBCT images taken at various configurations with a reference CBCT series.