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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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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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Douglas Kondziolka

Ding and colleagues at the University of Virginia provide an analysis of 444 patients who had stereotactic radiosurgery for an arteriovenous malformation (AVM) without evidence of prior symptomatic hemorrhage. 1 The series included patients with a mean AVM volume of 4.2 cm 3 (about 2 cm in diameter), but only 14% of the AVMs were in deep brain locations. The median radiosurgical dose was 20 Gy, which is typically associated with a high obliteration rate. As has been found in other studies, the authors noted that a higher obliteration rate was associated

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Claire Olson, Chun-Po Yen, David Schlesinger and Jason Sheehan

volume of the tumors at the time of radiosurgery was 4.6 cm 3 (range 0.3–18.7 cm 3 ). Fifteen of the 28 tumors received a single treatment, 6 were treated twice, 4 were treated 3 times, 2 were treated 4 times, and 1 was treated 5 times ( Table 2 ). The locations of the 28 tumors were as follows: parasellar, 9; posterior fossa, 6; frontal, 4; occipital, 3; temporal, 3; and parietal, 3. TABLE 2: Tumors requiring multiple GKSs * No. of GKSs No. of Cases 2 6 3 4 4 2 5 1 * Thirteen tumors were treated. Two tumors were

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

. Factors analyzed in these analyses included sex, age, preradiosurgery hemorrhage, preradiosurgery embolization, AVM volume, AVM location (superficial vs deep and noneloquent vs eloquent), location of draining veins (superficial vs deep), number of draining veins (single vs multiple), prescription dose, number of isocenters, radiological presence of RIC, SM grade, radiosurgery-based AVM scale (RBAS) score, and Virginia Radiosurgery AVM Scale (Virginia RAS) score. The patient, AVM, and treatment characteristics listed above were initially subjected to univariate

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

.6%), III in 163 (36.7%), IV in 30 (6.8%), and V in 3 (0.7%). We also calculated the modified Pittsburgh radiosurgery-based AVM score, which accounts for patient age, deep location, and AVM volume. 36 TABLE 1: Preradiosurgery patient and AVM characteristics in 444 cases Characteristic Value sex  male 222 (50.0%)  female 222 (50.0%) age (yrs)  mean 36.9  median 35.8  range 5–82 preradiosurgery embolization 122 (27.4%) preradiosurgery microsurgical resection 20 (4.5%) location

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Cheng-Chia Lee, Chun-Po Yen, Zhiyuan Xu, David Schlesinger and Jason Sheehan

available for all 109 patients. The study was approved by the institutional review board of the University of Virginia. The median age of these patients was 60.5 years, and the group included 51 males and 58 females. The median tumor volume was 16.8 cm 3 (range 6.0–74.8 cm 3 ). Most patients (68.8%%) had multiple intracranial lesions, and 31.2% of patients had metastasis to other organs. The most common tumor of origin was NSCLC (29.4% of cases), followed by breast cancer (22.9%) and melanoma (21.1%). Of note, those patients included in the current series with SCLC had

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

with unruptured AVMs, and all patients treated with volume-staged radiosurgery. The remaining 639 patients, classified as Cohort A, had ruptured AVMs and radiological follow-up of any duration. In an attempt to account for the latency of successes and complications typically associated with radiosurgery, another cohort, Cohort B, of patients with a minimum of 2 years of radiological follow-up was defined, and this group of patients had 465 ruptured AVMs and the minimum of 2 years of radiological follow-up. Finally, to optimize the power of statistical analyses used

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Dale Ding, Zhiyuan Xu, Ian T. McNeill, Chun-Po Yen and Jason P. Sheehan

.9)  visual disturbance 9 (13.8)  presyncope 7 (10.8) Tumor Characteristics Of the 90 meningiomas included for imaging analysis, 53 were parasagittal (58.9%) and 37 were parafalcine (41.1%). The median initial tumor volume was 3 cm 3 (range 0.1–15.4 cm 3 ). Preradiosurgery treatment included resection in 72 tumors (80%), embolization in 4 tumors (4.4%), and radiation therapy in 18 tumors (20%). An increase or decrease in tumor size was defined as a 15% increase or decrease in tumor volume. Tumor control was defined as decreased or unchanged tumor volume