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Shayan Moosa, Ching-Jen Chen, Dale Ding, Cheng-Chia Lee, Srinivas Chivukula, Robert M. Starke, Chun-Po Yen, Zhiyuan Xu and Jason P. Sheehan

large AVMs involve the delivery of radiation doses in stages with dose- or volume-staged SRS. Dose staging is described in the literature as either hypofractionated stereotactic radiotherapy (HSRT) or repeat SRS. Hypofractionated stereotactic radiotherapy is typically performed by administering several small doses of radiation to the AVM over a period of a few weeks. Repeat radiosurgery uses a higher initial dose (yet still lower than traditional single-session SRS for small to moderate AVMs), and another dose is administered after several months or years if there is

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Jason P. Sheehan and Jay Jagannathan

radiosurgical centers currently utilize doses of 12–24 Gy to the margin of the treatment volume and deliver spinal radiosurgery in 1–5 fractions. 15 , 20 , 23 The prescription dose depends in part upon the tumor location, histological characteristics, and volume as well as the fractionation scheme, surrounding organs at risk, and prior radiation therapy. Numerous studies have demonstrated the safety and effectiveness of intracranial stereotactic radiosurgery for treating metastatic disease to the brain. Local tumor control rates following radiosurgery range from

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Alana Tooze and Jason P. Sheehan

fraction. Multi-isocenter dose plans were used. Patients with NFAs received a mean margin dose of 17 Gy, and those with functioning adenomas such as Cushing’s disease received a mean margin dose of 25 Gy. In patients with NFAs and functioning adenomas, the ipsilateral maximal doses to the hippocampus were approximately 4–11 Gy and 8–14 Gy, respectively. In a study by our group in which we looked at the radiation dose to the anterior temporal lobe structures of radiosurgically treated patients, the mean dose and 50% volume dose to the anterior temporal lobe structures

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Adeel Ilyas, Ching-Jen Chen, Dale Ding, Davis G. Taylor, Shayan Moosa, Cheng-Chia Lee, Or Cohen-Inbar and Jason P. Sheehan

T he optimal management of large (volume > 10 cm 3 ) brain arteriovenous malformations (AVMs) is controversial. Options for intervention include resection, embolization, and stereotactic radiosurgery (SRS), alone or in combination. 6 , 16 , 17 , 26 , 64 , 79 As stand-alone treatment modalities for large AVMs, microsurgery is associated with relatively high rates of morbidity and mortality, whereas embolization results in low rates of complete nidal obliteration. 35 , 39 , 41 Single-session SRS (SS-SRS) is effective for many small- to medium-sized AVMs but

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Yi-Chieh Hung, Nasser Mohammed, Thomas Jose Eluvathingal Muttikkal, Kathryn N. Kearns, Chelsea Eileen Li, Aditya Narayan, David Schlesinger, Zhiyuan Xu and Jason P. Sheehan

published studies have failed to take into account the de novo volumes of the AVMs when comparing outcomes with embolization and SRS versus SRS alone, leading to inherent matching biases with prior analyses. 15 , 26 , 33 In the current study the case-control method was used in de novo AVM volume-matched cohorts to compare the long-term (10 years) favorable outcome, obliteration rate, and adverse effects of AVMs between 8 ml (approximately 2.5-cm diameter) and 39 ml (approximately 4.2-cm diameter) treated by embolization plus SRS and SRS alone. In addition, the number of

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Arnaldo Neves Da Silva, Kazuki Nagayama, David Schlesinger and Jason P. Sheehan

management of patients with brain metastasis. Methods Patient Inclusion From March 2002 to August 2006, 141 patients with brain metastases received staged treatment with GKS (Leksell Gamma Knife, Elekta Instrument AB) at the University of Virginia and had early follow-up MR imaging (< 1 month after GKS). Patients were included in this study if they had follow-up MR imaging within 30 days or less (mean neuroimaging follow-up interval = 13 days) from the initial GKS and had lesions measuring 0.5 cm 3 or greater. The criterion of a minimum tumor volume of 0.5 cm 3

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Robert M. Starke, Brian J. Williams, John A. Jane Jr. and Jason P. Sheehan

defined as a 15% or greater change in tumor volume as compared with the volume at the time of GKS. 37 To make this determination of tumor size, the tumor was outlined on radiographic images, and serial volumetric calculations were performed using the ImageJ program (NIH; http://rsb.info.nih.gov/ij/ ) in all patient imaging studies. 37 Any patient with tumor progression of more than 15% was considered a treatment failure, even if this progression stabilized with further GKS or microsurgery. Statistical Analysis Data are presented as median or mean and range for

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Robert M. Starke, Chun-Po Yen, Dale Ding and Jason P. Sheehan

history of hemorrhage, and 67% had AVMs in eloquent locations. Lesion volume was less than 2 cm 3 in 198 patients (19.6%), between 2 and 4 cm 3 in 486 (48.0%), and greater than 4 cm 3 in 328 (32.4%). Pretreatment patient and AVM characteristics are listed in Table 1 . TABLE 1: Patient characteristics and univariate predictors of favorable outcome Pretreatment Characteristics No. (%) * Favorable Outcome Odds Ratio 95% CI p Value males 517 (51.1) 1.10 0.85–1.42 0.462 mean age ± SD (yrs) 33.9 ± 15.8 0.68 0

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David J. Schlesinger, Faisal T. Sayer, Chun-Po Yen and Jason P. Sheehan

radiation dose distribution that conformally covers an irregularly shaped tumor volume. 2 At the vast majority of centers, treatment planning for GKS is conducted manually by an iterative approach using a planning system specific to the Gamma Knife, known as the Leksell GammaPlan or LGP (Elekta AB). The task of the treatment planner is to adjust parameters, including numbers, locations, beam-on times, and collimator configurations of each shot, to achieve a conformal dose distribution. Control of these parameters is generally an iterative process for which the results

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Christopher P. Cifarelli, David J. Schlesinger and Jason P. Sheehan

% volume of the optic apparatus. The optic apparatus volume was computed by contouring the optic nerves and chiasm on thin-slice MR images. Segmentation of the optic apparatus was done using GammaPlan and contours were drawn by the treating neurosurgeon. In the current study, the mean maximal dose was 44.6 Gy (range 10–70 Gy). The mean marginal dose was 19.9 Gy (range 1–30 Gy). Statistical Analysis The data were analyzed using S-PLUS 8.0 statistical software (MathSoft, Inc.). Testing for statistically significant associations between visual dysfunction following