Linear Accelerator Radiosurgery Research Articles

Optimized Conformal Total Body Irradiation with VMAT Using a Linear-Accelerator-Based Radiosurgery Treatment System in Comparison to the Golden Standard Helical TomoTherapy.

Modern irradiation techniques for optimized conformal TBI can be realized by Helical Tomotherapy (HT) or Volumetric Modulated Arc Therapy (VMAT), depending on the availability of suitable specialized equipment. In this dosimetric planning study, we compared both modalities and addressed the question of whether VMAT with small field sizes is also suitable as a backup in case of HT equipment malfunctions. For this purpose, we retrospectively used planning computed tomography (CT) data from 10 patients treated with HT with a total dose of 8 Gy (n = 5) or 12 Gy (n = 5) for treatment planning for VMAT with a small field size (36 × 22 cm). The target volume coverage, dose homogeneity at target volume, and dose reduction in organs at risk (OAR) (lungs, kidneys, lenses) were analyzed and compared. One patient was irradiated with both modalities due to a device failure of the HT equipment during the study, which facilitated a comparison in a real clinical setting. The findings indicate that in addition to a higher mean dose to the lenses in the 12 Gy group for VMAT and a better dose homogeneity in the target volume for HT, comparably good and adequate target dose coverage and dose reduction in the other OAR could be achieved for both modalities, with significantly longer treatment times for VMAT. In conclusion, after appropriate optimization of the treatment times, VMAT using linear accelerator radiosurgery technology can be used both as a backup in addition to HT and in clinical routines to perform optimized conformal TBI.

Assessing the long-term safety and efficacy of gamma knife and linear accelerator radiosurgery for vestibular schwannoma: A systematic review and meta-analysis.

Differences in long-term outcomes of single-fraction stereotactic radiosurgery (SRS) between gamma knife (GK) and linear accelerator (LINAC) systems for vestibular schwannoma (VS) management remain unclear. To investigate differences in safety and efficacy between modalities, we conducted a meta-analysis of studies over the past decade. MEDLINE, EMBASE, and Cochrane databases were queried for studies with the following inclusion criteria: English language, published between January 2010 and April 2020, cohort size ≥30, and mean/median follow-up ≥5 years. Odds ratios (OR) compared rates of tumor control, hearing preservation, and cranial nerve toxicities before and after SRS. Thirty-nine studies were included (29 GK, 10 LINAC) with 6516 total patients. Tumor control rates were 93% (95% CI 91-94%) and 94% (95% CI 91-97%) for GK and LINAC, respectively. Both GK (OR 0.06, 95% CI 0.02-0.13) and LINAC (OR 0.47, 95% CI 0.29-0.76) reduced odds of serviceable hearing. Neither GK (OR 0.71, 95% CI 0.41-1.22) nor LINAC (OR 1.13, 95% CI 0.64-2.00) impacted facial nerve function. GK decreased odds of trigeminal nerve (TN) impairment (OR 0.55, 95% CI 0.32-0.94) while LINAC did not impact TN function (OR 1.45, 95% CI 0.81-2.61). Lastly, LINAC offered decreased odds of tinnitus (OR 0.15, 95% CI 0.03-0.87) not observed with GK (OR 0.70, 95% CI 0.48-1.01). VS tumor control and hearing preservation rates are comparable between GK and LINAC SRS. GK may better preserve TN function, while LINAC decreases tinnitus rates. Future studies are warranted to investigate the efficacy of GK and LINAC SRS more directly.

Bibliometric analysis of the top-100 most cited articles on the radiosurgical management of cerebral arteriovenous malformation

Background: Radiosurgery is an effective, alternative treatment modality in managing patients with cerebral arteriovenous malformations (AVMs). The present study aims to highlight the scholarly impact of the top-100 most cited articles on the radiosurgical management of AVMs.Methods: A title-specific search using the keyword “arteriovenous malformation” was conducted in the Scopus database. The outcome of the search was rearranged based on the citations count. Articles were categorized into four entities; clinical, gamma knife radiosurgery, linear accelerator (LINAC) radiosurgery, and proton beam radiosurgery. The exclusion criteria were applied to spinal or non-intracranial AVM, conference papers, non-English articles predominantly discussing the endovascular or microsurgical management.Results: The top-100 articles on the radiosurgical management of AVM were published between 1972 and 2016. Approximately one-third of the publications were produced between 1995 and 2000. The average citations per year for all papers were seven. The most-studied entity was pertinent to the clinical application of gamma knife radiosurgery in AVM (68%). The United States was the most active country in studying the radiosurgical application in AVM. The Journal of Neurosurgery published approximately one-third of the most-cited articles in the list. The top-3 most contributing authors, publishing 80% of articles in the list, were Lunsford et al.Conclusion: The radiosurgical management of AVMs evolved significantly throughout the years. Identifications of the publication trends facilitate the acquisition of evidence-based articles for authors investigating various radiosurgical techniques in the treatment of AVMs.

Assessment of single isocenter linear accelerator radiosurgery for metastases and base of skull lesions.

Newer technology for stereotactic radiosurgery (SRS) should be assessed for different multi-leaf collimators (MLC). Assess plan quality of an automated, frameless, linear accelerator based (linac) planning and delivery system (HyperArc) for SRS using both standard MLC (SMLC) and high definition MLC (HDMLC) compared to a cobalt-60 based SRS system (Gamma Knife, GK). We re-planned twenty GK Perfexion-treated SRS patients (27 lesions) for HyperArc using SMLC and HDMLC. We assessed plan quality using the following metrics: gradient index (GI), Paddick and RTOG conformity indices (CIPaddick, CIRTOG), volume receiving half of prescription isodose (PIVhalf) and maximum dose to 0.03cc for brainstem, optic chiasm and optic nerves, and V12Gy for brain-GTV. Linac plans had better conformity with HDMLC being most conformal. GK exhibited better GI. PIVhalf demonstrated no statistically significant difference between HDMLC and GK, and SMLC was nominally worse than GK. Mean PIVhalf was generally 0.85cc larger for SMLC than HDMLC. For TV>1.0cc, the relative differences in CIRTOG, GI, and PIVhalf for SMLC vs. HDMLC were less than 21%. For TV less than<1.0cc, there were more obvious relative differences for SMLC vs. HDMLC in CIRTOG (mean 146%, max 700%), GI (mean 49%, max 162%), and PIVhalf (mean 77%, max 522%). Organ at risk doses were met in all plans. New linac-based plans positively compare to GK plans overall. HDMLC should be strongly considered for treatment of lesions<1.0cc given the significant improvements in conformity and PIVhalf over SMLC.

Communicating hydrocephalus after radiosurgery for vestibular schwannomas: does technique matter? A systematic review and meta-analysis.

Communicating hydrocephalus (cHCP) after radiosurgery (RS) for vestibular schwannomas (VS) has been reported. Many hypothetical mechanisms for this pathology have been proposed without consensus. The aim of this study is to determine if the platform used to treat the disease, Gamma Knife (GK) versus linear accelerator (LINAC)-based RS, makes a difference in outcome. We conducted a meta-analysis of databases PubMed and Cochrane to identify all articles for the period January 2000-August 2018 with the following inclusion criteria: (1) VS treated with single fraction SRS (2) > 10 patients (3) original reports only (4) hydrocephalus reported as complication (5) human study. A total of 7039 and 988 VS patients reported in 35 and 10 papers were treated with GK or LINAC RS, respectively. Demographic baseline characteristics not reported in aggregate did not differ between the two groups. The incidence of cHCP was 3% [95% CI 2-4] and 2% [95% CI 1-3] for GK and LINAC RS patients, respectively. Surgical CSF diversion was performed in 88% and 68% of patients evaluated for cHPC in the GK and LINAC group, respectively. Follow-up range was 30-150 and 29-92months for GK and LINAC, respectively. The incidence of cHCP following RS for VS is very low in both GK and LINAC treated patients, albeit not identical. The higher reported surgical intervention rate for VS patients treated with GK RS might be multi-factorial, including longer follow-up in the GK group.

Dedicated Linear Accelerator Radiosurgery for Classic Trigeminal Neuralgia: A Single-Center Experience with Long-Term Follow-Up

During the past decades, stereotactic radiosurgery, and Gamma Knife in particular, has proved its safety and efficacy for drug-resistant classic trigeminal neuralgia. However, few large series exist using linear accelerator (LINAC) reporting long-term follow-up. Between 2006 and 2015, 301 patients were treated by LINAC at our institution. The prescribed radiation dose was 90 Gy at the far anterior target. Clinical response was defined using the Barrow Neurological Institute scale. We considered grades I and IIIa as a successful response. Mean duration of follow-up was 54.6 months (range, 12-132 months). Two hundred and seventy-three patients (90.7%) were initially pain free, and 28 patients (9.3%) were unchanged. The actuarial probabilities of maintaining pain relief with or without medication (Barrow Neurological Institute grade I and IIIa) at 0.5, 1, 2, 4, 5, and 10 years were 88.7%, 85.0%, 76.1%, 68.8%, 65.8%, and 48.1%, respectively. Hypesthesia was present in only 26.2% of patients (very bothersome, 0.3%). No anesthesia dolorosa was reported. The actuarial probabilities of maintaining pain relief without further surgery at 0.5, 1, 2, 4, and 5 years were 99.3%, 98.3%, 95.8%, 91.0%, and 89.7%, respectively. Among all treated patients, 86.5% were satisfied by the procedure and would undergo stereotactic radiosurgery again. Stereotactic radiosurgery with dedicated LINAC is associated with high rates of long-term pain relief, with minimal invasiveness and rare complications. LINAC is a possible therapeutic alternative for drug-resistant trigeminal neuralgia and could be proposed to selected patients as the first intention therapy, among other surgical solutions.

LINAC treating more patients having brain arteriovenous malformations with stereotactic radiosurgery technique

Background: Linear accelerator (LINAC) based radiosurgery for a brain arteriovenous malformation (bAVM) is replacing gamma knife radiosurgery. We present clinical outcome, obliteration rates and predictor factors of treatment success following LINAC radiosurgery for bAVM which is not much addressed subject in Middle East. Methods: 13 patients who underwent LINAC radiosurgery for brain arteriovenous malformations from November 2008 to November 2011 in our radiation oncology department were retrospectively analyzed. Recollection of demographic data, AVM and treatment characteristics along with clinical and radiographic follow up information was done by reviewing the electronic data base. Results: All thirteen patients underwent stereotactic radiosurgery by linear accelerator based treatment delivery system (BrainLab) over three years. These included 7 males and 6 females, with median age of 22 years. Intracranial hemorrhage was a presenting feature in 7 (54 %) of patients. Prior embolization was done in 10 (77%) patients with 7 patients having more than once undergone this procedure. The location of AVM was superficial in 9 (70%) and deep in brain in 4 (30%) patients. The mean AVM score was 0.97 with 3 patients having AVM score ≥ 1 with mean Spetzler-Martin grade of 2.7 and 8 (62%) patients having grade 3 or more. Median follow up was 30 months. Mean dose delivered was 21.7 Gy in single fraction. Complete obliteration of AVM nidus was achieved in 9 (70%) patients while 4 patients (30%) had partial obliteration. Six patients (67 %) achieved complete obliteration among 9 who had AVM score of less than 1. Post radiosurgery neurological deficit occurred in only one patient in form of right temporal field loss. Conclusions: Linear accelerator based radiosurgery is promising treatment option for brain AVMs in majority of cases with reasonable adverse effect profile.

The impact of MRI steady-state sequences as an additional assessment modality in vestibular schwannoma patients after LINAC stereotactic radiotherapy or radiosurgery.

Data concerning the clinical usefulness of steady-state sequences (SSS) for vestibular schwannomas (VS) after linear accelerator (LINAC) stereotactic radiosurgery (SRS) or stereotactic radiotherapy (SRT) are scarce. The aim of the study was to investigate whether SSS provide an additional useful follow-up (FU) tool to the established thin-layered T1 sequences with contrast enhancement. Pre- and post-treatment SSS were identified in 45consecutive VS patients (2012-2016) with astandardized FU protocol including SSS at 2-3months and 6months/yearly in our prospective database and were retrospectively re-evaluated. The SSS were used throughout for the segmentation of the cochlea and partly of the trigeminal nerve in the treatment planning. Data analysis included signal conversion in SSS and possible correlation with neuro-otological outcome and volumetric assessment after a certain time interval. The series included 42SRS and 3SRT patients (31female/14male; mean age 59.3years, range: 25-81years). AnSSS signal conversion was observed in 20tumors (44.4%) within amean time of 11months (range: 7-15months). Mean FU time was 26months (median of 4FU visits) and demonstrated tumor volume shrinkage in 29cases (64.4%) correlating with FU time (p = 0.07). The incidence rate of combined shrinkage and signal conversion (48.3%) compared to those without signal conversion (51.7%) did not differ significantly (p = 0.49). In case of an early signal conversion at the first FU, aweak statistical significance (p = 0.05) for ahigher shrinkage rate of VS with signal conversion was found. Side effects in cases with signal conversion (9/20, 45%) were more frequently than without signal conversion (6/25, 24%) without reaching statistical significance (p = 0.13). Our data confirmed the usefulness of SSS for anatomical segmentation of VS in LINAC-SRS/SRT treatment planning and add data supporting their potential as an adjunctive FU option in VS patients.

Cavernous sinus meningiomas

Introduction: Tumors of the cranial base arising from or partially involving the cavernous sinus have represented a formidable challenge to neurosurgeons. Stereotactic radiosurgery represents an alternative to microsurgery for the management of cavernous sinus meningiomas. The present study aims to evaluate the results of radiosurgery in a large series of patients treated with a linear accelerator with a long-term follow-up. Patients and Methods: From 1993 through 2007, 462 patients with meningiomas underwent radiosurgery at the Chaim Sheba Medical Center LINAC radiosurgery unit. Of those, 117 had tumors involving predominantly the cavernous sinus. A mean follow-up of 67 months was obtained in 102 patients (range:12 to 180 months). Patients’ age ranged from 31 to 86 years (mean 57). Seventy two (70%) were females. Thirty five patients (34.3%) were initially submitted to microsurgery and 67 (65.6%) underwent stereotactic radiosurgery as the first treatment option. Patients were treated using a linear accelerator with cylindrical collimators in 44 patients (43.1%) and a minimultileaf collimator in 58 patients (56.8%). The prescription dose was delivered to the 60 to 80% isodose line (mean, 68%) in patients treated with cylindrical collimators, and to the 80% in those treated with a single conformal isocenter. Doses ranged between 12 and 17.5 Gy (mean, 13.5 Gy). Median tumor volume was 7.2 cm3 (range 0.61–23 cm3). Results: All patients were available for follow-up at 12 to 180 months after treatment (mean, 68 months; median, 60 months). The actuarial control rate was 98%. Fifty nine patients (58%) had a volume reduction and forty one (40%) had stable tumor volumes at the end of follow-up. Two tumors grew. Overall, 4 patients had a new lasting neurological deficit (facial hypesthesia or pain in two, trochlear neuropathy in two, and visual defect in one), for an incidence of 4% in persistent neurological complications. Conclusions: This series of linear accelerator radiosurgery confirms that in the short and long term, radiosurgery affords excellent control for cavernous sinus meningiomas with a very low incidence of complications. Radiosurgery can thus be regarded as the treatment of choice for cavernous sinus meningiomas.

Micro-Multileaf Collimator Linear Accelerator Radiosurgery for Vestibular Schwannomas

This study evaluates the efficacy of linear accelerator (LINAC) radiosurgery using micro multi-leaf collimator technique (μMLC) in the treatment of a consecutive series of patients with vestibular schwannomas. In this retrospective study, we enrolled 50 patients with non-neurofibromatosis type 2 vestibular schwannoma who were treated with μMLC LINAC-based SRS at University Hospital of Cologne, Germany. A minimum clinical follow-up of 24 months was conducted. Thirty-nine out of the 50 tumors (78 %) were treated with μMLC LINAC as a primary treatment (a newly diagnosed tumor). The remaining 11 vestibular schwannomas (22%) were treated as a salvage treatment (5 patients with a residual tumor; and 6 patients with a recurrent tumor following a microsurgical resection). The median tumor volume was 1.4 ml. The median tumor surface dose, median maximal dose and median therapeutic isodose were 12 Gy, 16 Gy and 77% respectively. Follow-up MR images showed that a tumor progression-free status was achieved for 95.7% of patients. Partial tumor shrinkage was observed after μMLC LINAC SRS for 21.3% of patients. No change in tumor size (a stable tumor) was noted for 74.5% of patients. Tumor progression was observed for 4.3% of patients. At the end of follow-up, the actuarial 5- year and 10 year progression-free survival after radiosurgery were both 95.7%. LINAC radiosurgery using a micro multi-leaf collimator for vestibular schwannomas smaller than 3 cm is effective in yielding a high local tumor control, whereas the treatment-related morbidity remains low.

Linear accelerator radiosurgery for arteriovenous malformations: Updated literature review

Arteriovenous malformations (AVMs) are the leading causing of intra-cerebral haemorrhage. Stereotactic radiosurgery (SRS) is an established treatment for arteriovenous malformations (AVM) and commonly delivered using Gamma Knife within dedicated radiosurgery units. Linear accelerator (LINAC) SRS is increasingly available however debate remains over whether it offers an equivalent outcome. The aim of this project is to evaluate the outcomes using LINAC SRS for AVMs used within a UK neurosciences unit and review the literature to aid decision making across various SRS platforms. Results have shown comparability across platforms and strongly supports that an adapted LINAC based SRS facility within a dynamic regional neuro-oncology department delivers similar outcomes (in terms of obliteration and toxicity) to any other dedicated radio-surgical platform. Locally available facilities can facilitate discussion between options however throughput will inevitably be lower than centrally based dedicated national radiosurgery units.

Outcome of radiosurgery treatment with a linear accelerator in patients with trigeminal neuralgia

IntroductionAn overview of the effectiveness of radiosurgery in patients diagnosed with trigeminal neuralgia with an analysis of potential predictors of good outcome. MethodsAll patients treated with linear accelerator radiosurgery between 2004 and 2011 were analysed. A dose of 60Gy dose was administered 1 to 2mm from the root entry zone with a maximum isodose of 20% delivered to the brainstem. Clinical results for pain control and any side effects were analysed at 12 and 36 months (BNI score). ResultsThe study included 71 patients (mean follow-up 50.5 months). Pain improvement at 12 months was observed in 68.11% of the total (28.98% with BNI score I–II; 39.12% with BNI score III) and at 36 months in 58.21% (23.88% BNI score I–II; 34.32% BNI score III). Average recovery time was 3.69 months and the relapse rate was 44.68%. Patients with typical pain displayed statistically significant differences in improvement rates at 12 and at 36 months (P<.047 and P<.002). Onset of improvement was analysed using Kaplan–Meyer plots. Statistically significant differences were observed between patients with typical and atypical pain at 36 months (P<.012) in Kaplan–Meyer plots. Side effects were recorded in 15 patients (20.89%), including 9 cases of facial numbness (13.43%); only 2 cases were clinically relevant (2.98%). ConclusionAccording to our results, radiosurgery is an effective treatment for trigeminal neuralgia, with few side effects. Typical pain seems to be a good predictor of pain relief.

Resultados de la aplicación de radiocirugía con acelerador lineal en pacientes con neuralgia del trigémino

IntroductionAn overview of the effectiveness of radiosurgery in patients diagnosed with trigeminal neuralgia with an analysis of potential predictors of good outcome. MethodsAll patients treated with linear accelerator radiosurgery between 2004 and 2011 were analysed. A dose of 60Gy dose was administered 1 to 2mm from the root entry zone with a maximum isodose of 20% delivered to the brainstem. Clinical results for pain control and any side effects were analysed at 12 and 36 months (BNI score). ResultsThe study included 71 patients (mean follow-up 50.5 months). Pain improvement at 12 months was observed in 68.11% of the total (28.98% with BNI score i-ii; 39.12% with BNI score iii) and at 36 months in 58.21% (23.88% BNI score i-ii; 34.32% BNI score iii). Average recovery time was 3.69 months and the relapse rate was 44.68%. Patients with typical pain displayed statistically significant differences in improvement rates at 12 and at 36 months (P<047 and P<.002). Onset of improvement was analysed using Kaplan-Meyer plots. Statistically significant differences were observed between patients with typical and atypical pain at 36 months (P<.012) in Kaplan-Meyer plots. Side effects were recorded in 15 patients (20.89%), including 9 cases of facial numbness (13.43%); only 2 cases were clinically relevant (2.98%). ConclusionAccording to our results, radiosurgery is an effective treatment for trigeminal neuralgia, with few side effects. Typical pain seems to be a good predictor of pain relief.

Stereotactic LINAC radiosurgery for the treatment of typical intracranial meningiomas. Efficacy and safety after a follow-up of over 12 years.

The efficacy and safety of stereotactic radiosurgery (SRS) for treatment of intracranial meningiomas has been demonstrated in numerous studies with short- and intermediate-term follow-up. In this retrospective single-center study, we present long-term outcomes of SRS performed with a linear accelerator (LINAC) for typical intracranial meningiomas. Between August 1990 and December 2007, 148 patients with 168 typical intracranial meningiomas were treated with stereotactic LINAC-SRS, either as primary treatment or after microsurgical resection. A median tumor surface dose of 12 Gy (range 7-20 Gy) and a median maximum dose of 24.1 Gy (range 11.3-58.6 Gy) was applied. The median target volume was 4.7 ml (range 0.2-32.8 ml, SD ± 4.8 ml). Overall mean radiological follow-up was 12.6 years. Tumor shrinkage was seen in 75 (44.6 %) and stable disease in 85 (50.6 %) cases. Eight of 168 meningiomas (4.8 %) showed local tumor progression. The tumor control rate (TCR) after 5, 10, and 15 years was 93.6 % at each time point, and the progression-free survival (PSF) rates were 92, 89, and 89 %, respectively. The neurological symptoms existing prior to LINAC-SRS improved in 77 patients (59.7 %), remained unchanged in 42 (32.6 %), and deteriorated in 10 (7.8 %) patients. Our study emphasizes the efficacy of LINAC-SRS for de novo, residual and recurrent typical intracranial meningiomas. A high long-term local TCR with a low morbidity rate could be achieved. LINAC-SRS should thus be considered as a primary treatment option, as one arm of a combined treatment approach for incompletely resected meningiomas, or as a salvage therapy for recurrences.

Linear accelerator radiosurgery for vestibular schwannomas: Results of medium-term follow-up

Background. To examine tumour control, via volume changes, and the complications of linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) treatment of vestibular schwannomas (VSs) on medium-term follow-up. Methods. Between September 2003 and November 2009 fifty consecutive patients with VSs treated with SRS using a marginal dose of 12.5 Gy utilizing a LINAC equipped with a micro-multileaf collimator were identified. Evaluation included serial magnetic resonance imaging (MRI), and neurological and hearing examinations. Results. The median tumour volume at treatment was 2.4 (range: 0.24–10.59) cm3. The intracranial diameter of the tumours ranged between 7.7 and 28.7 (median: 15.8) mm. Follow-up MRI was available for analysis on 49 patients. The median radiological follow-up period was 5.8 (range: 1.4–9.2) years. The median tumour volume at last follow-up was 1.1 (range: 0.03–5.3) cm3. VS decreased in size in 45 (90%) patients, with a median reduction in tumour volume of 1.46 (range: 0.06–9.29) cm3 or a median tumour size reduction of 59% of the baseline (range: 6–90%) in these patients. VS remained stable in 2 patients and increased in size in 2 patients. Only 1 patient (2%) required additional intervention (surgery). 15 patients had useful hearing pre-treatment; 10 post-treatment pure-tone audiograms of these patients were available. 5 (50%) patients still had useful hearing post treatment. Non-auditory adverse radiation effects included new (House–Brackmann grade II) or worsened facial nerve palsy (House–Brackmann grade II to grade V) in 2 (4%) patients and trigeminal sensory disturbance in 2 (4%) patients. Conclusions. At medium term, the vast majority of VSs treated with LINAC-based SRS exhibit tumour shrinkage. The slightly higher rate of facial nerve palsy compared with Gamma Knife surgery (GKS) results may be related to the learning curve. Other complications were similar to reported GKS results for VSs of comparable sizes.

Radiosurgery for brain metastases and cerebral edema

The objective of this study was to assess reduction in cerebral edema following linear accelerator radiosurgery (LINAC) as first line therapy for brain metastasis. We reviewed the medical records of all patients who underwent LINAC radiosurgery for brain metastasis at our institution during 2010–2012, and who had not previously undergone either surgery or whole brain radiotherapy. Data were analyzed for 55 brain metastases from 46 patients (24 males), mean age 59.9years. During the 2months following LINAC radiosurgery, the mean steroid dose decreased from 4.8 to 2.6mg/day, the mean metastasis volume decreased from 3.79±4.12cc to 2.8±4.48cc (p=0.001), and the mean edema volume decreased from 16.91±30.15cc to 12.85±24.47cc (p=0.23). The 17 patients with reductions of more than 50% in brain edema volume had single metastases. Edema volume in the nine patients with two brain metastases remained stable in five patients (volume change <10%, 0–2cc) and increased in four patients (by >10%, 2–14cc). In a subanalysis of eight metastases with baseline edema volume greater than 40cc, edema volume decreased from 77.27±37.21cc to 24.84±35.6cc (p=0.034). Reductions in brain edema were greater in metastases for which non-small-cell lung carcinoma and breast cancers were the primary diseases. Overall, symptoms improved in most patients. No patients who were without symptoms or who had no signs of increased intracranial pressure at baseline developed signs of intracranial pressure following LINAC radiosurgery. In this series, LINAC stereotactic radiosurgery for metastatic brain lesions resulted in early reduction in brain edema volume in single metastasis patients and those with large edema volumes, and reduced the need for steroids.

Evaluation of linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) for cerebral cavernous malformations: a 15-year single-center experience

BACKGROUND AND OBJECTIVESSurgery is the principal treatment for safely accessible hemorrhagic and symptomatic cavernous malformations. Nevertheless, the role of linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) in the management of high-risk, symptomatic cavernoma lesions warrants further refinement. In this study, we evaluate the use of LINAC-based SRS for cerebral cavernous malformations (CMs) and report our 15-year single-center experience.DESIGN AND SETTINGSA retrospective study from the Department of Radiation Oncology and the Department of Neurosurgery at Gulhane Military Medical Academy and Medical Faculty, Ankara from April 1998 to June 2013.PATIENTS AND METHODSFifty-two patients (22 females and 30 males) with cerebral CM referred to our department underwent high-precision single-dose SRS using a LINAC with 6-MV photons. All patients had at least 1 bleeding episode prior to radiosurgery along with related symptoms. Median dose prescribed to the 85% to 95% isodose line encompassing the target volume was 15 Gy (range, 10–20).RESULTSOut of the total 52 patients, follow-up data were available for 47 patients (90.4%). Median age was 35 years (range, 19–63). Median follow-up time was 5.17 years (range, 0.08–9.5) after SRS. Three hemorrhages were identified in the post-SRS period. Statistically significant decrease was observed in the annual hemorrhage rate after radiosurgical treatment (pre-SRS 39% vs post-SRS 1.21, P<.0001). Overall, there were no radiosurgery-related complications resulting in mortality.CONCLUSIONLINAC-based SRS may be considered as a treatment option for high-risk, symptomatic cerebral CM of selected patients with prior bleeding from lesions located at surgically inaccessible or eloquent brain areas.

Factors Determining the Clinical Complications of Radiosurgery for AVM

To identify the predictors of symptomatic post-radiation T2 signal change in patients with arteriovenous malformations (AVM) treated with radiosurgery. The charts of 211 consecutive patients with arteriovenous malformations treated with either gamma knife radisurgery or linear accelerator radiosurgery between 2000-2009 were retrospectively reviewed. 168 patients had a minimum of 12 months of clinical and radiologic follow-up following the procedure and complete dosage data. Pretreatment characteristics and dosimetric variables were analyzed to identify predictors of adverse radiation effects. 141 patients had no clinical symptomatic complications. 21 patients had global or focal neurological deficits attributed to symptomatic edema. Variables associated with development of symptomatic edema included a non-hemorrhagic symptomatic presentation compared to presentation with hemorrhage, p=0.001; OR (95%CI) = 6.26 (1.99, 19.69); the presence of venous rerouting compared to the lack of venous rerouting, p=0.031; OR (95% CI) = 3.25 (1.20, 8.80); radiosurgery with GKS compared to linear accelerator radiosurgery p = 0.012; OR (95% CI) = 4.58 (1.28, 16.32); and the presence of more than one draining vein compared to a single draining vein p = 0.032; OR (95% CI) = 2.82 (1.06, 7.50). We postulated that the higher maximal doses used with gamma knife radiosurgery may be responsible for the greater number of adverse radiation effects with this modality compared to linear accelerator radiosurgery. We found that AVMs with greater venous complexity and therefore instability resulted in more adverse treatment outcomes, suggesting that AVM angioarchitecture should be considered when making treatment decisions.

LINAC Stereotactic Radiosurgery for brain arteriovenous malformation: a single institutional experience from Saudi Arabia

† Abstract Background: Linear accelerator (LINAC) based radiosurgery for a brain arteriovenous malformation (bAVM) is replacing gamma knife radiosurgery. We present clinical outcome, obliteration rates and predictor factors of treatment success following LINAC radiosurgery for bAVM which is not much addressed subject in Middle East. Results: All thirteen patients underwent stereotactic radiosurgery by linear accelerator based treatment delivery system (BrainLab) over three years. These included 7 males and 6 females, with median age of 22 years. Intracranial hemorrhage was a presenting feature in 7 (54 %) of patients. Prior embolization was done in 10 (77%) patients with 7 patients having more than once undergone this procedure. The location of AVM was superficial in 9 (70%) and deep in brain in 4 (30%) patients. The mean AVM score was 0.97 with 3 patients having AVM score ≥ 1 with mean Spetzler-Martin grade of 2.7 and 8 (62%) patients having grade 3 or more. Median follow up was 30 months. Mean dose delivered was 21.7 Gy in single fraction. Complete obliteration of AVM nidus was achieved in 9 (70%) patients while 4 patients (30%) had partial obliteration. Six patients (67 %) achieved complete obliteration among 9 who had AVM score of less than 1. Post radiosurgery neurological deficit occurred in only one patient in form of right temporal field loss. Conclusions: Linear accelerator based radiosurgery is promising treatment option for brain AVMs in majority of cases with reasonable adverse effect profile.

Delivery Accuracy of Stereotactic Radiosurgery (SRS) With Tomotherapy as Compared to Linear Accelerator and Robotic-based Radiosurgery

Delivery Accuracy of Stereotactic Radiosurgery (SRS) With Tomotherapy as Compared to Linear Accelerator and Robotic-based Radiosurgery