***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Stereotactic radiosurgery ( SRS ) and fractionated stereotactic radiotherapy ( SRT ) have been recognized as an alternative to surgery for small to medium sized vestibular schwannoma ( VS ) . This study analysed and compared the outcomes of VS treated with the first Thail and installation of a dedicated Linac-based stereotactic radiation machine using single-fraction radiosurgery ( SRS ) , hypofraction stereotactic radiotherapy ( HSRT ) and conventional fraction stereotactic radiotherapy ( CSRT ) . From 1997 to 2010 , a total of 139 consecutive patients with 146 lesions of VS were treated with X-Knife at Ramathibodi hospital , Bangkok , Thail and .  SRS was selected for 39 lesions ( in patients with small tumors ≤3 cm and non-serviceable hearing function ) , whereas HSRT ( 79 lesions ) and CSRT ( 28 lesions ) were given for the remaining lesions that were not suitable for SRS . With a median follow-up time of 61 months ( range , 12–143 ) , the 5-year local control rate was 95 , 100 and 95 % in the SRS , HSRT and CSRT groups , respectively . Hearing preservation was observed after SRS in 75 % , after HSRT in 87 % and after CSRT in 63 % of the patients . Cranial nerve complications were low in all groups . There were no statistically significant differences in local control , hearing preservation or complication between the treatment schedules . In view of our results , it may be preferable to use HSRT over CSRT for patients with serviceable hearing because of the shorter duration of treatment Objective Largely , watchful waiting is the initial policy for patients with small-sized or medium-sized vestibular schwannoma , because of slow growth and relatively minor complaints , that do not improve by an intervention . If intervention ( microsurgery , radiosurgery or fractionated radiotherapy ) becomes necessary , the choice of intervention appears to be driven by the patient 's or clinician 's preference rather than by evidence based . This study addresses the existing evidence based on controlled studies of these interventions . Design A systematic Boolean search was performed focused on controlled intervention studies . The quality of the retrieved studies was assessed based on the Sign-50 criteria on cohort studies . Data sources Pubmed / Medline , Embase , Cochrane Central Register of Controlled Trials and reference lists . Study selection Six eligibility criteria included a controlled intervention study on a newly diagnosed solitary , vestibular schwannoma reporting on clinical outcomes . Two prospect i ve and four retrospective observational , controlled studies published before November 2011 were selected . Data analysis Two review ers independently assessed the method ological quality of the studies and extracted the outcome data using predefined formats . Results Neither r and omised studies , nor controlled studies on fractionated radiotherapy were retrieved . Six studies compared radiosurgery and microsurgery in a controlled way . All but one were confined to solitary tumours less than 30 mm in diameter and had no earlier interventions . Four studies qualified for trustworthy conclusions . Among all four , radiosurgery showed the best outcomes : there were no direct mortality , no surgical or anaesthesiological complications , but better facial nerve outcome , better preservation of useful hearing and better quality of life . Conclusions The available evidence indicates radiosurgery to be the best practice for solitary vestibular schwannomas up to 30 mm in cisternal diameter PURPOSE To assess long term outcomes and factors determining hearing preservation after low dose linac stereotactic radiosurgery ( SRS ) for acoustic neuroma ( AN ) at the Royal Adelaide Hospital using prospect ively collected data . MATERIAL AND METHODS Between 1994 and 2010 , 102 patients had SRS for AN . Five patients had neurofibromatosis type 2 , six sporadic cases had relapsed after surgery , and the remaining 91 sporadic cases had primary SRS .  Dose was 12 or 14 Gy . Sustained changes ≥ 2 mm in any diameter were deemed significant , and useful hearing was defined as inter-aural pure tone average ( PTA ) ≤ 50 dB. Possible prognostic factors for hearing retention were tested by dividing the patients at pre-specified cutpoints : age ( 60 years ) , maximum tumour diameter ( 20 mm ) , initial PTA ( 20 dB ) and dose ( 12 vs 14 Gy ) . RESULTS Eighty-four of the 91 sporadic primary SRS cases were evaluable for tumour control with at least one post-treatment MRI . Their median follow-up was 65 mo ( range 10 - 184 mo ) . Eighty-two ( 97.6 % ) were controlled , the remaining two requiring salvage surgery for progression at 5.75 and 9.75 years . Also , one of the post-operative cases required surgery at 2.1 years after SRS . For the 50 sporadic primary SRS patients with initially useful hearing , median age was 56 ( range 21 - 76 ) , median initial PTA 16 dB ( range -11 to + 45 dB ) and median tumour diameter 21 mm ( range 10 - 33 mm ) . Four received 14 Gy , the rest 12 Gy . After SRS , 19 patients ( 38 % ) retained useful hearing . The Kaplan-Meier estimated preservation rate at 5 years was 50 % ( 95 % CI 36 - 64 % ) but by 10 years , this had fallen to 23 % ( 95 % CI 12 - 41 % ) . On univariate analysis , the only significant factor was initial PTA ( P < 0.0001 ) . The estimated risk of hearing loss  after SRS for patients with initial PTA ≥ 20 dB was 5.0 ( 95 % CI 2.2 - 11.2 ) times that with PTA < 20 dB. CONCLUSIONS Tumour control was excellent ( 99/102=97 % freedom from surgical salvage ) . Hearing preservation was strongly dependent on initial PTA , but there was a steady fall-off in hearing out to at least 10 years The latest version of Leksell GammaPlan ( LGP ) is equipped with Digital Imaging and Communication in Medicine ( DICOM ) image-processing functions including image co- registration . Diagnostic magnetic resonance imaging ( MRI ) taken prior to Gamma Knife treatment is available for virtual treatment pre-planning . On the treatment day , actual dose planning is completed on stereotactic MRI or computed tomography ( CT ) ( with a frame ) after co- registration with the diagnostic MRI and in association with the virtual dose distributions . This study assesses the accuracy of image co- registration in a phantom study and evaluates its usefulness in clinical cases . Images of three kinds of phantoms and 11 patients are evaluated . In the phantom study , co- registration errors of the 3D coordinates were measured in overall stereotactic space and compared between stereotactic CT and diagnostic CT , stereotactic MRI and diagnostic MRI , stereotactic CT and diagnostic MRI , and stereotactic MRI and diagnostic MRI co-registered with stereotactic CT . In the clinical study , target contours were compared between stereotactic MRI and diagnostic MRI co-registered with stereotactic CT . The mean errors of coordinates between images were < 1 mm in all measurement areas in both the phantom and clinical patient studies . The co- registration function implemented in LGP has sufficient geometrical accuracy to assure appropriate dose planning in clinical use OBJECT Microsurgical excision is an established treatment for vestibular schwannoma ( VS ) . In 1992 the authors used a patient question naire to evaluate the functional outcome and quality of life in a series of 224 consecutive patients . In addition , starting with gamma knife surgery ( GKS ) in 1992 , the authors decided to use the same methodology to evaluate prospect ively the results of this modality to compare the two alternatives . METHODS Among the 500 patients who were included prospect ively , the authors only evaluated patients in whom GKS was the primary treatment for unilateral VS . Four years of follow up was available for the first 104 consecutive patients . Statistical analysis of the GKS and microsurgery population s has shown that only a comparison of Stage II and III ( according to the Koos classification ) was meaningful in terms of group size and preoperative risk factor distribution . Objective results and question naire answers from the first 97 consecutive patients were compared with the 110 patients in the microsurgery group who fulfilled the inclusion criteria . Question naire answers indicated that 100 % of patients who underwent GKS compared with 63 % of patients who underwent microsurgery had no new facial motor disturbance . Forty-nine percent of patients who underwent GKS ( 17 % in the microsurgery study ) had no ocular symptoms , and 91 % of patients treated with GKS ( 61 % in the microsurgery study ) had no functional deterioration after treatment . The mean hospitalization stay was 3 days after GKS and 23 days after microsurgery . All the patients who underwent GKS who had been employed , except one , had kept the same professional activity ( 56 % in the microsurgery study ) . The mean time away from work was 7 days for GKS ( 130 days in the microsurgery study ) . Among patients whose preoperative hearing level was Class 1 according to the Gardner and Robertson scale , 70 % preserved functional hearing after GKS ( Class 1 or 2 ) compared with only 37.5 % in the microsurgery group . CONCLUSIONS Functional side effects happen during the first 2 years after radiosurgery . Findings after 4 years of follow up indicated that GKS provided better functional outcomes than microsurgery in this patient series OBJECTIVE : To determine the outcome and toxicity in patients with vestibular schwannomas treated with conventionally fractionated stereotactic radiotherapy ( SRT )  and to identify prognostic factors that are predictive of outcome . METHODS : Between 1992 and 2001 , 70 patients with vestibular schwannomas were treated with linear accelerator-based SRT in our institutions . Eleven patients had neurofibromatosis Type II ( NF2 ) . The median age was 53 years ( range , 17–82 yrs ) . The median tumor volume was 2.4 cm3 ( range , 0.05–21.1 cm3 ) . The indications for SRT were distributed as follows : 47 % newly diagnosed , 31 % progressive tumors after watchful waiting , 3 % adjuvant postoperative radiation , and 19 % recurrent tumors after surgical resection . The median dose was 54 Gy in 1.8 Gy per fraction , prescribed to 95 % of the isodose line . Relocatable stereotactic frames were used for daily treatments . The median follow-up was 45.3 months . RESULTS : Tumor recurrence was defined as progressive enlargement of tumor on follow-up magnetic resonance imaging studies . One patient had a tumor recurrence at 38 months after SRT .  The actuarial tumor control rates were 100 and 98 % at 3 and 5 years , respectively . Three patients with a median tumor volume of 16.2 cm3 required surgical resection for persistent or increasing symptoms at a median of 37 months . The actuarial freedom from resection rates were 98 and 92 % at 3 and 5 years , respectively . In multivariate analysis , tumor volume at time of treatment was predictive for neurosurgical intervention ( surgical resection or shunt placement ) after SRT ( P = 0.001 ) . The 3- and 5-year actuarial rates of freedom from any neurosurgical intervention were 100 and 97 % for patients with tumor volume less than 8 cm3 and 74 and 47 % respectively for patients with tumor of at least 8 cm3 ( P < 0.0001 ) . The 3-year actuarial rates of facial and trigeminal nerve preservation were 99 and 96 % , respectively . Surgery before SRT was predictive of posttreatment trigeminal neuropathy . The 3-year actuarial rates of freedom from trigeminal neuropathy were 86 and 98 % for patients with and without previous resection , respectively ( P = 0.04 ) . There was no difference in tumor control and cranial nerve function preservation rates seen in NF2 patients compared with non-NF2 patients . No second primary cancer or malignant transformation was observed . CONCLUSION : SRT in the conventionally fractionated approach results in a very favorable outcome with minimal toxicity , with results comparable to those of the best of the radiosurgery series . Patients with large tumors are more likely to undergo neurosurgical interventions after SRT .  Patients who have undergone previous surgery are at increased risk of developing trigeminal neuropathy PURPOSE In this single-institution trial , we investigated whether fractionated stereotactic radiation therapy is superior to single-fraction linac-based radiosurgery with respect to treatment-related toxicity and local control in patients with vestibular schwannoma . METHODS AND MATERIAL S All 129 vestibular schwannoma patients treated between 1992 and June 2000 at our linac-based radiosurgery facility were analyzed with respect to treatment schedule . Dentate patients were prospect ively selected for a fractionated schedule of 5 x 4 Gy and later on 5 x 5 Gy at the 80 % isodose in 1 week with a relocatable stereotactic frame . Edentate patients were prospect ively selected for a nonfractionated treatment of 1 x 10 Gy and later on 1 x 12.5 Gy at 80 % isodose with an invasive stereotactic frame . Both MRI and CT scans were made in all 129 patients within 1 week before treatment . All patients were followed yearly with MRI and physical examination . RESULTS A fractionated schedule was given to 80 patients and 
    Output:
    
ConclusionS RS and FSRT are both noninvasive treatment alternatives for patients with VS with low rates of treatment failure in need of rescue therapy .
In this selection of patients , the progression-free survival rates were on the order of 92–100 % for both treatment options .
Finally , 19 articles reported long-term tumor control after SRS , while only 2 articles reported long-term FSRT results , making effect estimates more uncertain for FSRT