Commissioning and validation of a Monte Carlo algorithm for spine stereotactic radiosurgery.

PURPOSE: A 6FFF Monte Carlo (MC) dose calculation algorithm was commissioned for spine stereotactic radiosurgery (SRS). Model generation, validation, and ensuing model tuning are presented. METHODS: The model was generated using in-air and in-water commissioning measurements of field sizes between 10 and 400 mm2 . Commissioning measurements were compared to simulated water tank MC calculations to validate output factors, percent depth doses (PDDs), profile sizes and penumbras. Previously treated Spine SRS patients were re-optimized with the MC model to achieve clinically acceptable plans. Resulting plans were calculated on the StereoPHAN phantom and subsequently delivered to the microDiamond and SRSMapcheck to verify calculated dose accuracy. Model tuning was performed by adjusting the model's light field offset (LO) distance between physical and radiological positions of the MLCs, to improve field size and StereoPHAN calculation accuracy. Following tuning, plans were generated and delivered to an anthropomorphic 3D-printed spine phantom featuring realistic bone anatomy, to validate heterogeneity corrections. Finally, plans were validated using polymer gel (VIPAR based formulation) measurements. RESULTS: Compared to open field measurements, MC calculated output factors and PDDs were within 2%, profile penumbra widths were within 1 mm, and field sizes were within 0.5 mm. Calculated point dose measurements in the StereoPHAN were within 0.26% ± 0.93% and -0.10% ± 1.37% for targets and spinal canals, respectively. Average SRSMapcheck per-plan pass rates using a 2%/2 mm/10% threshold relative gamma analysis was 99.1% ± 0.89%. Adjusting LOs improved open field and patient-specific dosimetric agreement. Anthropomorphic phantom measurements were within -1.29% ± 1.00% and 0.27% ± 1.36% of MC calculated for the vertebral body (target) and spinal canal, respectively. VIPAR gel measurements confirmed good dosimetric agreement near the target-spine junction. CONCLUSION: Validation of a MC algorithm for simple fields and complex SRS spine deliveries in homogeneous and heterogeneous phantoms has been performed. The MC algorithm has been released for clinical use.

Initial single surgeon evaluation comparing C-arm fluoroscopy with the Cirq robotic assistance device for instrumentation of the thoracolumbar spine.

OBJECTIVE: To compare our experience with pedicle screw insertion of the thoracolumbar spine utilizing the Cirq robot assistance device compared with traditional paradigm using fluoroscopy. METHODS: We prospectively collected data of patients undergoing pedicle screw instrumentation in the thoracolumbar spine performed by a single surgeon at three different centers. One center took delivery of the Cirq robotic assistance device. Remaining two centers used C-arm fluoroscopy. Demographic information, diagnosis, total OR time, intraoperative complications, unexpected return to the operating room, and hospital readmissions within 90 days was compared between the two cohorts. RESULTS: A total of 166 screws were placed during the study period. Forty percent were placed using the Cirq. Two thirds the patients had traumatic diagnoses with remaining degenerative spine disease. There were no misplaced pedicle screws in either group. While total OR time was longer in the Cirq cohort by 123 min (p = 0.04), actual procedural time was not statistically different (p = 0.11). Nonetheless there were also more hospital readmissions in the Cirq cohort compared with the C arm group (p = 0.04). CONCLUSIONS: Thoracolumbar screws inserted using C-arm fluoroscopy utilize less total operating room time with similar accuracy compared with the Cirq robotic assistance device. Further studies are warranted.

Monitoring frequency of intra-fraction patient motion using the ExacTrac system for LINAC-based SRS treatments.

PURPOSE: The aim of this study was to investigate the intra-fractional patient motion using the ExacTrac system in LINAC-based stereotactic radiosurgery (SRS). METHOD: A retrospective analysis of 104 SRS patients with kilovoltage image-guided setup (Brainlab ExacTrac) data was performed. Each patient was imaged pre-treatment, and at two time points during treatment (1st and 2nd mid-treatment), and bony anatomy of the skull was used to establish setup error at each time point. The datasets included the translational and rotational setup error, as well as the time period between image acquisitions. After each image acquisition, the patient was repositioned using the calculated shift to correct the setup error. Only translational errors were corrected due to the absence of a 6D treatment table. Setup time and directional shift values were analyzed to determine correlation between shift magnitudes as well as time between acquisitions. RESULTS: The average magnitude translation was 0.64 ± 0.59 mm, 0.79 ± 0.45 mm, and 0.65 ± 0.35 mm for the pre-treatment, 1st mid-treatment, and 2nd mid-treatment imaging time points. The average time from pre-treatment image acquisition to 1st mid-treatment image acquisition was 7.98 ± 0.45 min, from 1st to 2nd mid-treatment image was 4.87 ± 1.96 min. The greatest translation was 3.64 mm, occurring in the pre-treatment image. No patient had a 1st or 2nd mid-treatment image with greater than 2 mm magnitude shifts. CONCLUSION: There was no correlation between patient motion over time, in direction or magnitude, and duration of treatment. The imaging frequency could be reduced to decrease imaging dose and treatment time without significant changes in patient position.

Use of the Brainlab Disposable Stylet for endoscope and peel-away navigation.

BACKGROUND: Neuronavigation, the ability to perform real-time intra-operative guidance during cranial and/or spinal surgery, has increased both accuracy and safety in neurosurgery [2]. Cranial navigation of existing surgical instruments using Brainlab requires the use of an instrument adapter and clamp, which in our experience renders an endoscope 'top-heavy', difficult to manipulate, and the process of registration of the adapter quite time-consuming. METHODS: A Brainlab Disposable Stylet was used to navigate fenestration of an entrapped temporal horn in a pediatric case. Accuracy was determined by target visualization relative to neuronavigation targeting. Accuracy was also calculated using basic trigonometry to establish the maximum tool tip inaccuracy for the disposible stylet inserted into a peel-away (Codman) and endoscope. RESULTS: The Brainlab Disposable Stylet was easier to use, more versatile, and as accurate as use of an instrument adapter and clamp. The maximum tool-tip inaccuracy for the endoscope was 0.967 mm, and the Codman peel-away 0.489 mm. A literature review did not reveal any reports of use of the Brainlab Disposable Stylet in this way, and we are unaware of this being used in common neurosurgical practice. CONCLUSIONS: We would recommend this technique in endoscopic cases that require use of Brainlab navigation.

Pinless Electromagnetic Neuronavigation During Awake Craniotomies: Technical Pearls, Pitfalls, and Nuances.

BACKGROUND: Awake craniotomies are often performed with rigid pin fixation to support optical neuronavigation. Newer electromagnetic (EM) neuronavigation technology now enables unpinned cranial neurosurgery while maintaining robust intraoperative image guidance. Here, we share technical nuances, operative pearls, and lessons learned from our institutional experience using Curve EM neuronavigation during awake, unpinned craniotomies. METHODS: We describe our process for patient positioning, instrumentation setup, system registration, intraoperative navigation, and surgical adjunct use (e.g., intraoperative neuromonitoring and intraoperative magnetic resonance imaging) in detail. At each step, we provide pearls for success and tips for pitfall avoidance based on our experience. RESULTS: Ten patients underwent awake pinless intra-axial tumor resection using Curve EM neuronavigation from May 2021 to August 2022 with a single surgeon. Postoperative transient neurological deficits were seen in 8 of 10 cases (80.0%), as all resections were taken to functional margins. Of the 9 patients with a 3-month follow-up visit at the time of publication, all 9 (100%) had improved or stable preoperative symptoms. No surgical complications, clinically appreciable inaccuracies, intraoperative losses of registration, unexpected postoperative magnetic resonance imaging findings, or errors related to the use of EM neuronavigation occurred. CONCLUSIONS: The technical pearls outlined here will help interested neurosurgeons integrate EM neuronavigation into awake craniotomies. In our experience, using unpinned neuronavigation during awake cases provides many advantages to the patient, surgeon, and entire operative team. It has thus become the standard practice at our institution.

A phantom-based study and clinical implementation of brainlab's treatment planning system for radiosurgical treatments of arteriovenous malformations.

PURPOSE: Development of a simple, phantom-based methodology allowing for pilot applications for the Elements TPS cranio-vascular module and clinical implementation prior to AVM treatments. METHODS: A customized phantom was developed to be visible in MRI and CT images. High resolution digital subtraction angiograms (DSAs) and CT images of the phantom were acquired and imported into the Brainlab Elements treatment planning system. A clinical treatment plan with 5 arcs was generated in cranial vascular planning module and delivered to the phantom using a Varian TrueBeam STx Linac equipped with HD-MLCs and Brainlab ExacTrac imaging system for non-coplanar setup verification. The delivered dose was verified using a calibrated ionization chamber placed in the phantom. Upon verification of the TPS workflow, three patients with AVM who have been treated to date at our center using the Brainlab's cranial vascular module for AVM are presented here for retrospective review. RESULTS: The difference between the planed and measured dose by the ionization chamber was found to be less than 1%. Following a successful dose verification study, a clinical workflow was created. Currently, three AVM patients have been treated successfully. Clinical aspects of imaging and treatment planning consideration are presented in retrospective setting. CONCLUSIONS: Dose verification of the Brainlab Elements cranial vascular planning module for intracranial SRS treatments of AVM on Varian TrueBeam was successfully implemented using a custom-made phantom with <1% discrepancy. The Brainlab Elements' cranial vascular module was successfully implemented in clinical workflow to treat patients with AVM. This manuscript provides a guideline for clinical implementation of frameless Linac-based AVM treatment using the Brainlab Elements TPS.

A dosimetric comparative analysis of Brainlab elements and Eclipse RapidArc for spine SBRT treatment planning.

Purpose. This is a dosimetric study comparing stereotactic body radiotherapy (SBRT) plans of spine tumors using Brainlab Elements Spine planning module against Eclipse RapidArc plans. Dose conformity, dose gradient, dose fall-off, and patient-specific quality assurance (QA) metrics were evaluated. Methods:Twenty patients were immobilized in supine position using half Vac-Lok. A prescription dose of 16 Gy in a single fraction was planned for Varian TrueBeam. Conformal arc plans were generated with Pencil beam (PB), MonteCarlo (MC) in Elements, and RapidArc with Acuros XB algorithm in Eclipse using identical treatment geometry.Results. Eclipse, Elements PB, and Elements MC generated dosimetrically conformal plans having Inverse Paddick Conformity Index (IPCI) <1.3. All plans satisfied the dose constraints to target and OARs. Elements PB had a sharper gradient than Elements MC with average GI of 3.67(95% CI: 3.52-3.82) and 4.06 (95% CI: 3.93-4.20) respectively. Eclipse plans were more homogeneous with mean HI = 1.22 (95% CI: 1.20-1.23) that is lower than others. Average maximum clinical target volume (CTV) doses were higher in Elements MC with 22.31 Gy (95% CI: 21.87-22.74), while PB plans have 21.15 Gy (95% CI: 20.36-21.96), respectively. Elements MC and PB plans had lower average dose to 0.35 c.c. of spinal cord (D0.35cc) of 7.60 Gy (95% CI: 7.18-8.02) and 8.42 Gy (95% CI: 7.83-9.01). All plans had >95% points passing the gamma QA criteria at 3%/2 mm.Conclusion. All treatment plans achieved clinically acceptable target coverage >95% and meet spinal cord dose limits. Smart optimization in Brainlab Elements spine module produced dosimetrically superior plans by better spinal cord sparing.

Local anatomy, stimulation site, and time alter directional deep brain stimulation impedances.

Directional deep brain stimulation (DBS) contacts provide greater spatial flexibility for therapy than traditional ring-shaped electrodes, but little is known about longitudinal changes of impedance and orientation. We measured monopolar and bipolar impedance of DBS contacts in 31 patients who underwent unilateral subthalamic nucleus deep brain stimulation as part of a randomized study (SUNDIAL, NCT03353688). At different follow-up visits, patients were assigned new stimulation configurations and impedance was measured. Additionally, we measured the orientation of the directional lead during surgery, immediately after surgery, and 1 year later. Here we contrast impedances in directional versus ring contacts with respect to local anatomy, active stimulation contact(s), and over time. Directional contacts display larger impedances than ring contacts. Impedances generally increase slightly over the first year of therapy, save for a transient decrease immediately post-surgery under general anesthesia during pulse generator placement. Local impedances decrease at active stimulation sites, and contacts in closest proximity to internal capsule display higher impedances than other anatomic sites. DBS leads rotate slightly in the immediate postoperative period (typically less than the angle of a single contact) but otherwise remain stable over the following year. These data provide useful information for setting clinical stimulation parameters over time.

Alignment analysis of Brainlab knee 3 navigation-guided total knee arthroplasty using the adjusted mechanical method.

Purpose: With the application of navigation technology in Total Knee Arthroplasty (TKA), TKA procedures have become various. Studies have shown that navigation can improve the alignment of patients' lower limbs. To verify this conclusion, we collected the clinical data from patients who underwent Brainlab knee 3 navigation-guided TKA. Brainlab knee 3 is a completely new software that takes a different approach to address the current challenges of navigated TKA. During the procedure, we applied the Adjusted Mechanical Alignment (AMA) principle and took soft tissue balance as a priority. We aim to explore the patients' lower limb alignment changes who underwent the Brainlab knee 3 navigation-guided TKA using the AMA method. Methods: Fifty consecutive patients who underwent total knee arthroplasty using the Brainlab knee3 knee navigation system (Smith&Nephew) from January to August 2021 by the same doctor (Yunsu Chen) in the Department of Joint Surgery of the Shanghai Sixth People's Hospital were included. Hip-Knee-Ankle Angle (HKAA), anatomic Femur Tibia Angle (FTA), Lateral Distal Femoral Angle (LDFA), and medial proximal tibia angle (MPTA) were measured on preoperative and postoperative full-length lower-limbs x-ray films or weight-bearing anterior and lateral knee radiographs for observational and descriptive study. The preoperative and postoperative knee alignment changes were analyzed through paired t-test or nonparametric Wilcoxon test using SPSS 25.0 software. Results: Pre-operative and post-operative HKAA both obeyed normal distribution. The mean preoperative HKAA was 169.8° (154.9-178.7°) with a standard deviation of 5.41; the postoperative HKAA was 175.7° (168.4-180.0°) with a standard deviation of 2.81. Using the two-sample paired t-test to analyze, the result showed P = 0.000 < 0.05; a statistically significant difference exists. The preoperative and postoperative FTA obeyed normal distribution as well. The mean preoperative FTA was 174.7° (163.4-179.9°) with a standard deviation of 3.90; postoperative 175.6° (167.0-179.9°) with a standard deviation of 2.77. Using the two-sample paired t-test to analyze, the result showed P = 0.140 > 0.05, the difference was not statistically significant. The preoperative LDFA was normally distributed, while postoperative LDFA was not. The mean preoperative LDFA was 90.7° (83.5-99.6°) with a standard deviation of 3.83; the median of postoperative LDFA was 91.6° (86.0-103.2°) with an interquartile range of 2.93. Using the two-sample paired Wilcoxon test, the result showed P = 0.052 > 0.05; the difference was not statistically significant. Preoperative MPTA obeyed normal distribution, while postoperative MPTA did not. The mean preoperative MPTA was 83.5° (72.7-92.9°), with a standard deviation of 3.66; the median of postoperative MPTA was 89.3° (84.6-95.6°), with an interquartile range of 1.45. Using the two-sample paired Wilcoxon test, the result shows P = 0.000 < 0.05; a statistically significant difference exists. Conclusion: In our study, AMA alignment was applied in Brainlab Knee3 computer navigation-assisted total knee arthroplasty. The femoral and tibial osteotomy angles were minimally adjusted according to soft tissue situations to reduce soft tissue release. We found AMA alignment provides good control of knee alignment in the coronal plane of the lower limbs, which is a reliable technique.

Operative Technique and Lessons Learned From Surgical Implantation of the NeuroPace Responsive Neurostimulation® System in 57 Consecutive Patients.

BACKGROUND: The Responsive Neurostimulation (RNS)® System (NeuroPace, Inc) is an implantable device designed to improve seizure control in patients with medically refractory focal epilepsy. Because it is relatively new, surgical pearls and operative techniques optimized from experience beyond a small case series have yet to be described. OBJECTIVE: To provide a detailed description of our operative technique and surgical pearls learned from implantation of the RNS System in 57 patients at our institution. We describe our method for frame-based placement of amygdalo-hippocampal depth leads, open implantation of cortical strip leads, and open installation of the neurostimulator. METHODS: We outline considerations for patient selection, preoperative planning, surgical positioning, incision planning, stereotactic depth lead implantation, cortical strip lead implantation, craniotomy for neurostimulator implantation, device testing, closure, and intraoperative imaging. RESULTS: The median reduction in clinical seizure frequency was 60% (standard deviation 63.1) with 27% of patients achieving seizure freedom at last follow up (median 23.1 mo). No infections, intracerebral hemorrhages, or lead migrations were encountered. Two patients experienced lead fractures, and four lead exchanges have been performed. CONCLUSION: The techniques set forth here will help with the safe and efficient implantation of these new devices.

Monte Carlo simulation of conical collimators for stereotactic radiosurgery with a 6 MV flattening-filter-free photon beam.

PURPOSE: Conical collimators, or cones, are tertiary collimators that attach to a radiotherapy linac and are suited for the stereotactic radiosurgery treatment of small brain lesions. The small diameter of the most used cones makes difficult the acquisition of the dosimetry data needed for the commissioning of treatment planning systems. Although many publications report dosimetric data of conical collimators for stereotactic radiosurgery, most of the works use different setups, which complicates comparisons. In other cases, the cone output factors reported do not take into account the effect of the small cone diameter on the detector response. Finally, few data exist on the dosimetry of cones with flattening-filter-free (FFF) beams from modern linac models. This work aims at obtaining a dosimetric characterization of the conical collimators manufactured by Brainlab AG (Munich, Germany) in a 6 MV FFF beam from a TrueBeam STx linac (Varian Medical Systems). METHODS: Percentage depth dose curves, lateral dose profiles and cone output factors were obtained using Monte Carlo simulations for the cones with diameters of 4, 5, 6, 7.5, 8, 10, 12.5, 15, 17.5, 20, 25, and 30 mm. The simulation of the linac head was carried out with the PRIMO Monte Carlo software, and the simulations of the cones and the water phantom were run with the general-purpose Monte Carlo code PENELOPE. The Monte Carlo model was validated by comparing the simulation results with measurements performed for the cones of 4, 5, and 7.5 mm of diameter using a stereotactic field diode, a microDiamond detector and EBT3 radiochromic film. In addition, for those cones, simulations and measurements were done for comparison purposes, by reproducing the experimental setups from the available publications. RESULTS: The experimental data acquired for the cones of 4, 5, and 7.5 mm validated the developed Monte Carlo model. The simulations accurately reproduced the experimental depths of maximum dose and the dose ratio at 20- and 10-cm depth (PDD20/10 ). A good agreement was obtained between simulated and experimental lateral dose profiles: The differences in the full-width at half-maximum were smaller than 0.2 mm, and the differences in the penumbra 80%-20% were smaller than 0.25 mm. The difference between the simulated and the average of the experimental output factors for the cones of 4, 5, and 7.5 mm of diameter was 0.0%, 0.0%, and 3.0%, respectively, well within the statistical uncertainty of the simulations (4.4% with coverage factor k = 2). It was also found that the simulated cone output factors agreed within 2% with the average of output factors reported in the literature for a variety of setup conditions, detectors, beam qualities, and cone manufacturers. CONCLUSION: A Monte Carlo model of cones for stereotactic radiosurgery has been developed and validated. The cone dosimetry dataset obtained in this work, consisting of percentage depth doses, lateral dose profiles and output factors, is useful to benchmark data acquired for the commissioning of cone-based radiosurgery treatment planning systems.

Amalgamation of Cranio-maxillofacial Surgery and Technological Development.

How often should results go according to plan? No surgeon is perfect all the time, yet surgery is a discipline driven by results. Surgeons have therefore turned to technology to improve not only their outcomes but also how often they achieve high-quality results. Almost entire human creativity today, from the standpoint of its efficiency and expediency, is conditioned with the existence of technology. Progresses in computer-based technologies including virtual reality simulators, augmented reality, virtual plastic surgery software and computer-aided design/computer-aided manufacturing systems have resulted in new modalities for instruction and practice of oral and maxillofacial surgery. The efficiency offered by new technology to conventional model surgery can return hours to a surgeon's day through a more streamlined work-up and smoother intra-operative experience with confidence in the surgical accuracy. Continuous quality improvement has been a mantra in health care for many years. Surgeons are always looking to improve not only the quality of their results but also the consistency with which these results are achieved. To this end, new technology is being incorporated into or replacing traditional diagnostics and treatment planning.

Intrafraction motion during frameless radiosurgery using Varian HyperArcTM and BrainLab ElementsTM immobilization systems.

Commercial systems such as Varian HyperArcTM and BrainLab Elements MultiMetTM have been developed that allow radiosurgery treatment of multiple brain metastases using a single isocenter. Each software package places increased demands on frameless immobilization and requires the use of a specific immobilization system: the QFix-Encompass system for Varian and the BrainLab frameless-mask system for BrainLab. At our institution, patients receiving traditional radiosurgery (one isocenter per target lesion) were treated using both immobilization systems. Intrafraction motion was determined for each patient using multiple cone-beam CT scans and the same image-registration software during treatment. There were no statistically-significant differences in mean absolute translational shifts between the two mask systems, with a mean 3D-vector motion of approximately 0.43 mm for both systems. There were also no statistically-significant differences in the mean absolute rotational shifts between the two mask systems. Although the average residual errors were insignificant between the mask systems, special attention should be paid to individual maximum shifts with both systems. Large maximum rotational misalignments could present significant misalignment of lesions as distance increases from the isocenter. Finally, large maximum shifts highlight the need for real-time monitoring of patient movement during radiosurgery of multiple lesions using a single isocenter.

Monte Carlo calculated output correction factors for Gafchromic EBT3 film for relative dosimetry in small stereotactic radiosurgery fields.

To calculate small field output correction factors, [Formula: see text], for Gafchromic EBT3 film using Monte Carlo simulations. These factors were determined for a Novalis Trilogy linear accelerator equipped with Brainlab circular cones with diameters of 4.0 to 30.0 mm. The BEAMnrc Monte Carlo code was used to simulate the Novalis Trilogy linear accelerator and the Brainlab cones with diameters 4.0 to 30 mm. The DOSXYZnrc code was used to simulate Gafchromic EBT3 film with the atomic composition specified by the manufacturer. Small field correction factors were calculated according to new IAEA TRS-483 Code of Practice for small field dosimetry. The depth of calculation was 10 cm and a source to surface distance of 100 cm. The X-ray beam used in the simulations was a 6 MV SRS. The correction factors were then used to determine field output factors with Gafchromic EBT3 film. These field output factors were validated using three solid state detectors and applying correction factors from the TRS-483 Code of Practice. The solid state detectors were IBA SFD diode, PTW 60018 SRS diode and PTW 60019 microDiamond. The Monte Carlo calculated output correction factors, [Formula: see text], for Gafchromic EBT3 film ranged between 0.998 to 1.004 for Brainlab circular cones with diameters between 4.0 and 30.0 mm. The uncertainty for these factors was 2.0%. The field output factors obtained with Gafchromic EBT3 film were within 2% of the mean results obtained with the three solid state detectors. For field sizes 4 mm diameter and above, Gafchromic EBT3 film has field output correction factors within 1% of unity. Therefore, Gafchromic EBT3 film can be considered to be correction less and supports the assumption made about this film in the TRS-483 Code of Practice.

First experiences with the Airo mobile intraoperative CT scanner in acetabular surgery-An analysis of 10 cases.

BACKGROUND: Being a proven method in trauma and spine surgery, intraoperative 3D imaging (CBCT) has intrinsic deficits in difficult anatomy and with artifacts because of metal implants. The purpose of this study was to evaluate the use of intraoperative computed tomography (iCT) in acetabular surgery. METHODS: Ten cases of acetabular fractures that were operated with intraoperative use of the mobile CT scanner Brainlab Airo were analyzed. Data were compared with a historical group of 17 patients. RESULTS: Additional fluoroscopy time was 24.2 seconds (6-91), which was significantly lower than in the control group where it was 211.4 seconds (77-446; P < 0.000). Operation time did not differ significantly (iCT group 196.8 min [122-288], control group 240.8 min [71-411], P = 0.234). CONCLUSION: iCT provides images of a reliable high quality and assessability. Radiation exposure to the staff is reduced while surgery time is not altered significantly. Quality of intraoperative imaging and thus patient care can substantially improve patient outcome.

Development and evaluation of an automatic tumor segmentation tool: a comparison between automatic, semi-automatic and manual segmentation of mandibular odontogenic cysts and tumors.

INTRODUCTION: In the treatment of cancer in the head and neck region, computer-assisted surgery can be used to estimate location and extent by segmentation of the tumor. This article presents a new tool (Smartbrush), which allows for faster automated segmentation of the tumor. METHODS: This new method was compared with other well-known techniques of segmentation. Thirty-eight patients with keratocystic odontogenic tumors were included in this study. The tumors were segmented using manual segmentation, threshold-based segmentation and segmentation using Smartbrush. All three methods were compared concerning usability, time expenditure and accuracy. RESULTS: The results suggest that segmentation using Smartbrush is significantly faster with comparable accuracy. CONCLUSIONS: After a period of adjustment to the program, one can comfortably get reliable results that, compared with other methods, are not as dependent on the user's experience. Smartbrush segmentation is a reliable and fast method of segmentation in tumor surgery.

Stereotactic radiosurgery and stereotactic radiotherapy for brain metastases.

Stereotactic radiosurgery (SRS) and hypofractionated stereotactic radiotherapy (HFSRT) have become important treatment modalities for brain metastases. While effective, there are still areas of extensive debate on its appropriate use in patients with life-limiting diseases. This review provides an overview of the indications and challenges of SRS and HFSRT in the management of brain metastases.