bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative analysis of movement of a cervical target during stereotactic radiosurgery using the Leksell Gamma Knife Perfexion
Authors: Tonetti Daniel , Bhatnagar Jagdish , Lunsford L. Dade 
Published: November 2018

Object
The design of the Leksell Gamma Knife Perfexion facilitates stereotactic radiosurgery (SRS) on cervical spine targets provided that the target itself is located superior to the standard G stereotactic head frame base ring and does not move. This study was designed to measure potential deviations of targets in the upper cervical spine while using the currently available Leksell Coordinate Frame G.

Methods
A commercially available skull-and–cervical spine model was adapted for SRS using the Leksell Gamma Knife Perfexion. The Leksell Coordinate Frame G was attached to the model, and both CT and fluoroscopic imaging were performed to determine the potential for target deviation at standard Gamma Knife treatment angles of 70°, 90°, and 110°. In addition, target deviations observed at various heights of the patient positioning table were analyzed using a pair of orthogonal fluoroscopic images obtained at a standard 90° gamma angle and compared with target position as it relates to a reference bed height of 4.5 cm.

Results
An examination of multiple radiopaque targets embedded in or affixed to the model showed target deviations ranging from as low as 3.53 mm at the medial occiput–C1 junction to 15.56 mm at the C3–4 level during 70° extension. Target deviations at 110° flexion relative to targets on a 90° CT scan included deviations ranging from 0.58 mm at the medial occiput–C1 junction to 13.32 mm at the medial C3–4 level.
Relative to targets observed at the Perfexion table height of 4.5 cm, target deviation at a table height of 3 cm varied from 0.44 to 5.26 mm. At a table height of 5.5 cm, target deviation varied from 0.44 to 3.60 mm, and at a maximum height of 5.8 cm, target deviation varied from 0.62 to 4.30 mm.

Conclusions
Target deviation grossly exceeded clinical tolerance and was greater the farther the distance between the cranial base and the cervical spine target. Simple and reproducible methods that allow SRS centers to immobilize the patient's cervical spine using the currently available model G head frame are necessary to increase the range of targets that can be treated safely using the Leksell Gamma Knife Perfexion.
Are frequent dental x-ray examinations associated with increased risk of vestibular schwannoma?
Authors: Han Yueh-Ying , Berkowitz Oren , Talbott Evelyn , Kondziolka Douglas , Donovan Maryann , Lunsford L. Dade 
Published: November 2018

Object
The authors evaluated the potential role of environmental risk factors, including exposure to diagnostic or therapeutic radiation and to wireless phones that emit nonionizing radiation, in the etiology of vestibular schwannoma (VS).

Methods
A total of 343 patients with VSs who underwent Gamma Knife surgery performed between 1997 and 2007 were age and sex matched to 343 control patients from the outpatient degenerative spinal disorders service at the University of Pittsburgh Medical Center. The authors obtained information on previous exposure to medical radiation, use of wireless phone technologies, and other environmental factors thought to be associated with the development of a VS. Conditional multivariate logistic regression was used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs).

Results
After adjusting for race, education, cigarette smoking, alcohol consumption, occupational exposure to noise, use of cell phones, and family history of cancer, the authors identified only a single factor that was associated with a higher risk of VS: individuals exposed to dental x-rays once a year (aOR = 2.27, 95% CI = 1.01–5.09) or once every 2–5 years (aOR = 2.65, 95% CI = 1.20–5.85), compared with those exposed less than once every 5 years. Of interest, a history of exposure to radiation related to head or head-and-neck computed tomography was associated with a reduced risk of VS (aOR = 0.52, 95% CI = 0.30–0.90). No relationship was found between the use of cell phones or cordless phones and VS.

Conclusions
Patients with acoustic neuromas reported significantly more exposure to dental x-rays than a matched cohort control group. Reducing the frequency of dental x-ray examinations may decrease the potential risk of VS.
Same-day stereotactic aspiration and Gamma Knife surgery for cystic intracranial tumors
Authors: Liu Xiaomin , Yu Qi , Zhang Zhiyuan , Zhang Yipei , Li Yanhe , Liu Dong , Jia Qiang , Zheng Ligao , Xu Desheng 
Published: November 2018

Object
The goal of this study was to evaluate the efficacy and safety of same-day stereotactic aspiration and Gamma knife surgery (GKS) for cystic intracranial tumors.

Methods
Between 1996 and 2007, 77 patients harboring cystic intracranial tumors underwent a same-day procedure of MRI-guided cyst aspiration followed by GKS. The diagnoses were metastatic tumor in 43 patients, glial tumor in 12 patients, vestibular schwannoma in 10 patients, craniopharyngioma in 9 patients, and hemangioblastoma in 3 patients.

Results
An improvement in symptoms was achieved in 68 patients (88.3%) immediately after cyst aspiration. The mean tumor volume in this group of patients was 25.1 cm3 before aspiration and 11.1 cm3 afterward. Hemorrhage during the course of aspiration was encountered in 1 patient. Transient nausea after cyst aspiration developed in 3 patients. There was no treatment-related hematoma, seizure, neurological deficit, or infection. The median follow-up period was 16 months (range 6–108 months). Tumor control was achieved in 50 (80.6%) of 62 patients who participated in follow-up for at least 6 months.

Conclusions
The same-day stereotactic aspiration and GKS procedure was safe in patients with cystic brain tumors. Prompt symptom relief was obtained after cyst aspiration. The decrease in tumor volume following aspiration made GKS more effective because a higher prescription dose could be administered with a lower possibility of radiation-induced side effects.
Dose-volume effects on brainstem dose tolerance in radiosurgery
Authors: Xue Jinyu , Goldman H. Warren , Grimm Jimm , LaCouture Tamara , Chen Yan , Hughes Lesley , Yorke Ellen 
Published: November 2018

Object
Dose-volume data concerning the brainstem in stereotactic radiosurgery (SRS) for trigeminal neuralgia (TN) were analyzed in relation to associated complications. The authors present their set of data and compare it with currently cited information on brainstem dose tolerance associated with conventional fractionated radiation therapy and hypofractionated radiation treatment of other diseases.

Methods
Stereotactic radiosurgery for TN delivers a much higher radiation dose to the brainstem in a single fraction than doses delivered by any other procedures. A literature survey of articles on radiosurgery for TN revealed no incidences of severe toxicity, unlike other high-dose procedures involving the brainstem. Published data on brainstem dose tolerance were investigated and compared with dose-volume data in TN radiosurgery. The authors also performed a biological modeling study of dose-volume data involving the brainstem in cases of TN treated with the Gamma Knife, CyberKnife, and linear accelerator–based systems.

Results
The brainstem may receive a maximum dose as high as 45 Gy during radiosurgery for TN. The major complication after TN radiosurgery is mild to moderate facial numbness, and few other severe toxic responses to radiation are observed. The biologically effective dose of 45 Gy in a single fraction is much higher than any brainstem dose tolerance currently cited in conventional fractionation or in single or hypofractionated radiation treatments. However, in TN radiosurgery, the dose falloff is so steep and the delivery so accurate that brainstem volumes of 0.1–0.5 cm3 or larger receive lower planned and delivered doses than those in other radiation-related procedures. Current models are suggestive, but an extensive analysis of detailed dose-volume clinical data is needed.

Conclusions
Patients whose TN is treated with radiosurgery are a valuable population in which to demonstrate the dose-volume effects of an extreme hypofractionated radiation treatment on the brainstem. The result of TN radiosurgery suggests that a very small volume of the brainstem can tolerate a drastically high dose without suffering a severe clinical injury. The authors believe that the steep dose gradient in TN radiosurgery plays a key role in the low toxicity experienced by the brainstem.
Role of Gamma Knife surgery in patients with 5 or more brain metastases
Authors: Mohammadi Alireza Mohammad , Recinos Pablo F. , Barnett Gene H. , Weil Robert J. , Vogelbaum Michael A. , Chao Samuel T. , Suh John H. , Marko Nicholas F. , Elson Paul , Neyman Gennady , Angelov Lilyana 
Published: November 2018

Object
The authors evaluated overall survival and factors predicting outcome in patients with ≥ 5 brain metastases who were treated with Gamma Knife surgery (GKS).

Methods
Medical records from patients with ≥ 5 brain metastases treated with GKS between 1997 and 2010 at the Cleveland Clinic Gamma Knife Center were retrospectively reviewed. Patient demographics, tumor characteristics, treatment-related factors, and outcome data were evaluated.

Results
One hundred seventy patients were identified, with a median age of 58 years. The female/male ratio was 1.2:1. Gamma Knife surgery was used as an upfront treatment in 35% of patients and as salvage treatment in 65% of patients with multiple brain metastases. The median overall survival after GKS was 6.7 months (95% CI 5.5–8.1). At the time of GKS, 128 patients (75%) had concurrent extracranial metastases, and in 69 patients (41%) multiple extracranial sites were involved. Ninety-two patients (54%) had a history of whole-brain radiation therapy, and 158 patients (93%) had a Karnofsky Performance Scale (KPS) score ≥ 70. The median total intracranial disease volume was 3.2 cm3 (range 0.2–37.2 cm3). A total intracranial tumor volume ≥ 10 cm3 was observed in 32 patients (19%). Lower KPS score at the time of treatment (p < 0.0001), patient age > 60 years (p = 0.004), multiple extracranial metastases (p = 0.0001), and greater intracranial burden of disease (p = 0.03) were prognostic factors for poor outcome in the univariate and multivariate analyses.

Conclusions
In this study, GKS was safe and effective for upfront and salvage treatment in patients with ≥ 5 brain metastases. Gamma Knife surgery should be considered as an additional treatment modality for these patients, especially in the subset of patients with favorable prognostic factors.
Calvarial and skull base metastases: expanding the clinical utility of Gamma Knife surgery
Authors: Kotecha Rupesh , Angelov Lilyana , Barnett Gene H. , Reddy Chandana A. , Suh John H. , Murphy Erin S. , Neyman Gennady , Chao Samuel T. 
Published: November 2018

ObjectTraditionally, the treatment of choice for patients with metastases to the calvaria or skull base has been conventional radiation therapy. Because patients with systemic malignancies are also at risk for intracranial metastases, the utility of Gamma Knife surgery (GKS) for these patients has been explored to reduce excess radiation exposure to the perilesional brain parenchyma. The purpose of this study was to report the efficacy of GKS for the treatment of calvarial metastases and skull base lesions.MethodsThe authors performed a retrospective chart review of 21 patients with at least 1 calvarial or skull base metastatic lesion treated with GKS during 2001–2013. For 7 calvarial lesions, a novel technique, in which a bolus was placed over the treatment site, was used. For determination of local control or disease progression, radiation therapy data were examined and posttreatment MR images and oncology records were reviewed. Survival times from the date of procedure were estimated by using Kaplan-Meier analyses.ResultsThe median patient age at treatment was 57 years (range 29–84 years). A total of 19 (90%) patients received treatment for single lesions, 1 patient received treatment for 3 lesions, and 1 patient received treatment for 4 lesions. The most common primary tumor was breast cancer (24% of patients). Per lesion, the median clinical and radiographic follow-up times were 10.3 months (range 0–71.9 months) and 7.1 months (range 0–61.3 months), respectively. Of the 26 lesions analyzed, 14 (54%) were located in calvarial bones and 12 (46%) were located in the skull base. The median lesion volume was 5.3 cm3 (range 0.3–55.6 cm3), and the median prescription margin dose was 15 Gy (range 13–24 Gy). The median overall survival time for all patients was 35.9 months, and the 1-year local control rate was 88.9% (95% CI 74.4%–100%). Local control rates did not differ between lesions treated with the bolus technique and those treated with traditional methods or between calvarial lesions and skull base lesions (p > 0.05). Of the 3 patients for whom local treatment failed, 1 patient received no further treatment and 2 patients responded to salvage chemotherapy. Subsequent brain parenchymal metastases developed in 2 patients, who then underwent GKS.ConclusionsGKS is an effective treatment modality for patients with metastases to the calvarial bones or skull base. For patients with superficial calvarial lesions, a novel approach with bolus application resulted in excellent rates of local control. GKS provides an effective therapeutic alternative to conventional radiation therapy and should be considered for patients at risk for calvarial metastases and brain parenchymal metastases.
Hemorrhage during pregnancy in the latency interval after stereotactic radiosurgery for arteriovenous malformations
Authors: Tonetti Daniel , Kano Hideyuki , Bowden Gregory , Flickinger John C. , Lunsford L. Dade 
Published: November 2018

ObjectThe presentation for patients with arteriovenous malformations (AVMs) is often intracranial hemorrhage; for women, this frequently occurs during the prime childbearing years. Although previous studies have addressed the risk for AVM hemorrhage during pregnancy, such studies have not assessed the risk for hemorrhage among women who become pregnant during the latency interval between stereotactic radiosurgery (SRS) and documented obliteration of the lesion. The authors sought to evaluate the risk for hemorrhage in patients who become pregnant during the latency interval after SRS.MethodsThis single-institution retrospective analysis reviewed the authors' experience with Gamma Knife SRS during 1987–2012. During this time, 253 women of childbearing age (median age 30 years, range 15–40 years) underwent SRS for intracranial AVM. The median target volume was 3.9 cm3 (range 0.1–27.1 cm3), and the median marginal dose was 20 Gy (range 14–38 Gy). For all patients, the date of AVM obliteration was recorded and the latency interval was calculated. Information about subsequent pregnancies and/or bleeding events during the latency interval was retrieved from the medical records and supplemented by telephone contact.ResultsAVM obliteration was confirmed by MRI or angiography at a median follow-up time of 39.3 months (range 10–174 months). There were 828.7 patient-years of follow-up within the latency interval between SRS and the date of confirmed AVM obliteration. Among nonpregnant women, 20 hemorrhages occurred before AVM obliteration, yielding an annual hemorrhage rate of 2.5% for nonpregnant women during the latency interval. Among women who became pregnant during the latency interval, 2 hemorrhages occurred over the course of 18 pregnancies, yielding an annual hemorrhage rate of 11.1% for women who become pregnant during the latency interval. For the 2 pregnant patients who experienced hemorrhage, the bleeding occurred during the first trimester of pregnancy.ConclusionsThe authors present the first series of data for women with intracranial AVMs who became pregnant during the latency interval after SRS. Hemorrhage during the latency interval occurred at an annual rate of 2.5% for nonpregnant women and 11.1% for pregnant women. The data suggest that pregnancy might be a risk factor for AVM hemorrhage during the interval between SRS and AVM obliteration. However, this suggestion is not statistically significant because only 18 patients in the study population became pregnant during the latency interval. To mitigate any increased risk for hemorrhage, patients should consider deferring pregnancy until treatment conclusion and AVM obliteration.
Long-term follow-up studies of Gamma Knife surgery for patients with neurofibromatosis Type 2
Authors: Sun Shibin , Liu Ali 
Published: November 2018

ObjectThe aim of this study was to evaluate long-term clinical outcomes after Gamma Knife surgery (GKS) for patients with neurofibromatosis Type 2 (NF2) and the role of GKS in the management of NF2.MethodsFrom December 1994 through December 2008, a total of 46 patients (21 male, 25 female) with NF2 underwent GKS and follow-up evaluation for at least 5 years at the Gamma Knife Center of the Beijing Neurosurgical Institute. GKS was performed using the Leksell Gamma Knife Models B and C. The mean age of the patients was 30 years (range 13–59 years). A family history of NF2 was found for 9 (20%) patients. The NF2 phenotype was thought to be Wishart for 20 (44%) and Feiling-Gardner for 26 (56%) patients. Among these 46 patients, GKS was performed to treat 195 tumors (73 vestibular schwannomas and 122 other tumors including other schwannomas and meningiomas). For vestibular schwannomas, the mean volume was 5.1 cm3 (median 3.6 cm3, range 0.3–27.3 cm3), the mean margin dose was 12.9 Gy (range 10–14 Gy), and the mean maximum dose was 27.3 Gy (range 16.2–40 Gy). For other tumors, the mean volume was 1.7 cm3 (range 0.3–5.5 cm3), the mean margin dose was 13.3 Gy (range 11–14 Gy), and the mean maximum dose was 26.0 Gy (range 18.0–30.4 Gy). The median duration of follow-up was 109 months (range 8–195 months).ResultsFor the 73 vestibular schwannomas that underwent GKS, the latest follow-up MR images demonstrated regression of 30 (41%) tumors, stable size for 31 (43%) tumors, and enlargement of 12 (16%) tumors. The total rate of tumor control for bilateral vestibular schwannomas in patients with NF2 was 84%. Of the 122 other types of tumors that underwent GKS, 103 (85%) showed no tumor enlargement. The rate of serviceable hearing preservation after GKS was 31.9% (15/47). The actuarial rates for hearing preservation at 3 years, 5 years, 10 years, and 15 years were 98%, 93%, 44%, and 17%, respectively. Of the 46 patients, 22 (48%) became completely bilaterally deaf, 17 (37%) retained unilateral serviceable hearing, and 7 (15%) retained bilateral serviceable hearing. The mean history of the disease course was 12 years (range 5–38 years).ConclusionsGKS was confirmed to provide long-term local tumor control for small- to medium-sized vestibular schwannomas and other types of tumors, although vestibular schwannomas in patients with NF2 responded less well than did unilateral sporadic vestibular schwannomas. Phenotype is the most strongly predictive factor of final outcome after GKS for patients with NF2. The risk for loss of hearing is high, whereas the risk for other cranial nerve complications is low.
Change in the cross-sectional area of the thecal sac following balloon kyphoplasty for pathological vertebral compression fractures prior to spine stereotactic radiosurgery
Authors: Lis Eric , Laufer Ilya , Barzilai Ori , Yamada Yoshiya , Karimi Sasan , McLaughlin Lily , Krol George , Bilsky Mark H. 
Published: November 2018

OBJECTIVEPercutaneous vertebral augmentation procedures such as vertebroplasty and kyphoplasty are often performed in cancer patients to relieve mechanical axial-load pain due to pathological collapse deformities. The collapsed vertebrae in these patients can be associated with varying degrees of spinal canal compromise that can be worsened by kyphoplasty. In this study the authors evaluated changes to the spinal canal, in particular the cross-sectional area of the thecal sac, following balloon kyphoplasty (BKP) prior to stereotactic radiosurgery (SRS).METHODSThe authors retrospectively reviewed the records of all patients with symptomatic vertebral compression fractures caused by metastatic disease who underwent kyphoplasty prior to single-fraction SRS. The pre-BKP cross-sectional image, usually MRI, was compared to the post-BKP CT myelogram required for radiation treatment planning. The cross-sectional area of the thecal sac was calculated pre- and postkyphoplasty, and intraprocedural CT imaging was reviewed for epidural displacement of bone fragments, tumor, or polymethylmethacrylate (PMMA) extravasation. The postkyphoplasty imaging was also evaluated for evidence of fracture progression or fracture reduction.RESULTSAmong 30 consecutive patients, 41 vertebral levels were treated with kyphoplasty, and 24% (10/41) of the augmented levels showed a decreased cross-sectional area of the thecal sac. All 10 of these vertebral levels had preexisting epidural disease and destruction of the posterior vertebral body cortex. No bone fragments were displaced posteriorly. Minor epidural PMMA extravasation occurred in 20% (8/41) of the augmented levels but was present in only 1 of the 10 vertebral segments that showed a decreased cross-sectional area of the thecal sac postkyphoplasty.CONCLUSIONSIn patients with preexisting epidural disease and destruction of the posterior vertebral body cortex who are undergoing BKP for pathological fractures, there is an increased risk of further mass effect upon the thecal sac and the potential to alter the SRS treatment planning.