Frameless Technique Research Articles

EP-2337: Comparison between two frameless immobilization techniques for Brain stereotactic radiosurgery

EP-2337: Comparison between two frameless immobilization techniques for Brain stereotactic radiosurgery

Improving patient safety during introduction of novel medical devices through cumulative summation analysis.

OBJECTIVE The aim of this study was to implement cumulative summation (CUSUM) analysis as an early-warning detection and quality assurance system for preclinical testing of the iSYS1 novel robotic trajectory guidance system. METHODS Anatomically accurate 3D-printed skull phantoms were created for 3 patients who underwent implantation of 21 stereoelectroencephalography electrodes by surgeons using the current standard of care (frameless technique). Implantation schema were recreated using the iSYS1 system, and paired accuracy measures were compared with the previous frameless implantations. Entry point, target point, and implantation angle accuracy were measured on postimplantation CT scans. CUSUM analysis was undertaken prospectively. RESULTS The iSYS1 trajectory guidance system significantly improved electrode entry point accuracies from 1.90 ± 0.96 mm (mean ± SD) to 0.76 ± 0.57 mm (mean ± SD) without increasing implantation risk. CUSUM analysis was successful as a continuous measure of surgical performance and acted as an early-warning detection system. The surgical learning curve, although minimal, showed improvement after insertion of the eighth electrode. CONCLUSIONS The iSYS1 trajectory guidance system did not show any increased risk during phantom preclinical testing when used by neurosurgeons who had no experience with its use. CUSUM analysis is a simple technique that can be applied to all stages of the IDEAL (idea, development, exploration, assessment) framework as an extra patient safety mechanism. Further clinical trials are required to prove the efficacy of the device.

A Frameless Stereotactic Implantation Technique for Depth Electrodes in Refractory Epilepsy Using Intraoperative Magnetic Resonance Imaging

Various complex techniques for depth electrode insertion in refractory epilepsy using preoperative imaging have been investigated. We evaluated a simple, accurate, cost-effective, and timesaving method using intraoperative magnetic resonance imaging (MRI). A neuronavigation-guided insertion tube attached to bone facilitated the placement of stereotactic percutaneous drill holes, bolt implantation, and frameless stereotactic insertion of depth electrodes. Image registration was carried out by head coil fiducials with trajectory planning and intraoperative electrode correction. In 6 patients with refractory epilepsy (3 women and 3 men; mean age, 30.0 years; range, 20-37 years), 58 depth electrodes (9-11 per patient) were placed. The mean length of the inserted electrodes was 37.3 mm ± 8.8 (mean ± SD) (range, 22.1-84.4 mm). The overall target point accuracy was 3.2 mm ± 2.2 (range, 0-8.6 mm), which was significantly different from the overall entry point accuracy of 1.4 mm ± 1.2 (P < 0.0001). All electrodes functioned perfectly, enabling high-quality stereo-electroencephalography recordings over a period of 7.3 days ± 0.5 (range, 7-8 days). The mean implantation time for 9-11 electrodes per patient was 115 minutes ± 36.3 (range, 75-160 minutes; 12 minutes for 1 electrode on average) including the intraoperative MRI (T1 three-dimensional magnetization-prepared rapid acquisition gradient echo, T2, and diffusion tensor imaging). There was no hemorrhage, infection, or neurologic deficit related to the procedure. Our frameless technique of depth electrode insertion using intraoperative MRI guidance is an accurate, reliable, cost-effective, and timesaving method for stereo-electroencephalography.

A comparison of clinical and radiologic outcomes between frame-based and frameless stereotactic radiosurgery for brain metastases

PurposeModern experiences in stereotactic radiosurgery (SRS) report noninvasive frameless techniques as an effective alternative to frame-based SRS. Frameless techniques potentially increase positional uncertainty and planning target volume margins are frequently used. Here, we compare rates of local control and radiation necrosis in frameless versus frame-based SRS. Methods and materialsNinety-eight patients (170 lesions) with radiologic and clinical follow-up were analyzed. Group 1 contained 34 patients (61 lesions) immobilized with an invasive stereotactic frame. Group 2 had 64 patients (109 lesions) immobilized with a frameless SRS mask. Patient, tumor, and treatment characteristics were recorded, as were intervals to local recurrence and radiation necrosis (asymptomatic and symptomatic). ResultsMedian patient age was 59 years (range, 25-89), and Karnofsky performance scale was 80 (range, 50-100). Median radiologic and clinical follow-up was 6.5 months (range, 0.7-44.3) and 7 months (range, 0.7-45.7). A median of 2 tumors were treated per course (range, 1-5) with a median dose of 18 Gy (range, 13-24 Gy). The median time to local failure was not reached, and Kaplan-Meier estimates of local failure were not statistically significant between groups (P = .303). Actuarial 6-month local failure rates were 7.2% in group 1 and 12.6% in group 2 (P = .295), with 12-month local failure rates of 14.5% and 26.8% (P = .185), respectively. There was no statistically significant difference in symptomatic (P = .391) or asymptomatic (P = .149) radiation necrosis. Six-month radiation necrosis was 0% in group 1 and 1.6% in group 2 (P = .311) with 12-month rates of 20.2% and 3.8%, respectively (P = .059). Median time to necrosis was not reached in group 1, but was 44 months in group 2. ConclusionsFrameless SRS demonstrates clinical outcomes comparable to frame-based techniques with respect to local failure and radiation necrosis.

Analysis of translational errors in frame-based and frameless cranial radiosurgery using an anthropomorphic phantom.

ObjectiveTo evaluate three-dimensional translational setup errors and residual errors in image-guided radiosurgery, comparing frameless and frame-based techniques, using an anthropomorphic phantom.Materials and MethodsWe initially used specific phantoms for the calibration and quality control of the image-guided system. For the hidden target test, we used an Alderson Radiation Therapy (ART)-210 anthropomorphic head phantom, into which we inserted four 5mm metal balls to simulate target treatment volumes. Computed tomography images were the taken with the head phantom properly positioned for frameless and frame-based radiosurgery.ResultsFor the frameless technique, the mean error magnitude was 0.22 ± 0.04 mm for setup errors and 0.14 ± 0.02 mm for residual errors, the combined uncertainty being 0.28 mm and 0.16 mm, respectively. For the frame-based technique, the mean error magnitude was 0.73 ± 0.14 mm for setup errors and 0.31 ± 0.04 mm for residual errors, the combined uncertainty being 1.15 mm and 0.63 mm, respectively.ConclusionThe mean values, standard deviations, and combined uncertainties showed no evidence of a significant differences between the two techniques when the head phantom ART-210 was used.

A Comparison of Clinical Outcomes Between Frame-based and Frameless Stereotactic Radiosurgery for Brain Metastases

Purpose/Objective(s): Though frame-based immobilization was the gold standard for cranial stereotactic radiosurgery (SRS), modern experiences report the non-invasive frameless techniques to be an effective alternative. Frameless techniques may potentially increase set up variation resulting in inferior targeting and commonly require additional margin to the target volume. Given these concerns, we aim to compare the rates of local control and radiation necrosis in frameless versus frame-based SRS. Materials/Methods: We reviewed all patients treated at our institution with SRS for brain metastases from 2008 to 2014. Ninety-eight patients (170 lesions) with radiologic and clinical follow-up had complete patient, tumor and treatment information. Group 1 consisted of 34 patients (61 lesions) immobilized with a standard head-ring. Group 2 had sixty-four patients (109 lesions) immobilized with an SRS specific mask. Patient-, tumor-, and treatment-characteristics were recorded as well as the intervals from treatment to local recurrence, radiation necrosis; elsewhere brain failure, and death. Radiographic asymptomatic radiation necrosis was included in the analysis. Results: Median patient age and KPS were 59 years (range 25 -89) and 80 (range 50-100), respectively. Median radiologic and clinical follow up were 6.5 months (range 0.7-44.3) and 7 months (range 0.7-45.7). A median of 2 tumors were treated per treatment course (range 1-5) with a median dose of 18 Gy (range 13-24 Gy). Six targets failed locally in Group 1 with 6and 12-month failure rates of 7.2% and 14.5%. Eighteen local failures were documented in Group 2 with 6-and 12-month failure estimates of 15.3% and 30.8%. Comparison of the Kaplan Meier estimates with the log-rank test demonstrated a p-value of 0.1446. Thirtyone patients (50%) in Group 1 had additional margins with a 0.69 cc mean increase in target volume compared to 93 patients (85%) with a 1.2 cc mean increase in Group 2. Eleven targets had radiation necrosis (8 symptomatic) in Group 1 with 6and 12-month necrosis rate estimates of 1.7% and 36.5%. Radiation necrosis was documented in 14 targets (6 symptomatic) in Group 2 with 6and 12-month necrosis estimates of 3.1% and 16.5%. Log-rank statistics showed a p-value of 0.3911. Cox regression for univariate analysis identified variables predictive for necrosis. Only SRS dose >17 Gy was statistically significant on multivariate analysis (HR 0.303, 95% CI 0.1-0.89). There were no statistically significant factors found on multivariate analysis for local progression. Conclusion: In this report, frameless SRS techniques demonstrated quality clinical outcomes without statistically significant differences in local control or radiation necrosis when compared to frame-based SRS. Author Disclosure: N.R. Bennion: None. T. Malouff: None. V. Verma: None. A.O. Wahl: None. W. Zhen: None. C. Lin: None.

Lung stereotactic body radiotherapy (SBRT): a single institution’s outcomes and methodology in the context of a literature review

Lung cancer is the leading cause of cancer death in the United States and worldwide, with the incidence of early stage lung cancer anticipated to rise with increasing use of screening CT. Improvements in systemic therapy have increased the need for durable local control both in primary lung cancer as well as oligometastatic disease to the lung. Since 2007, the University of California San Diego (UCSD) has employed SBRT in the treatment of early stage primary non-small cell histology (NSCLC), intrapulmonary oligometastases, and multiple primary lung cancers (MPLCs) with high efficacy and low toxicity using a frameless technique that involves non-invasive image guidance. We review our center’s general approach to management including our experience with clinical outcomes and toxicity in the context of a review of the literature, details of our preferred technique (including simulation and real-time tumor tracking), as well as our results and strategy for patient follow-up using PET to monitor tumor response in the post-SBRT setting.

Management of patients with recurrent glioblastoma using hypofractionated stereotactic radiotherapy.

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults. The chance of cure is very limited due to treatment-refractory disease course with frequent recurrences despite aggressive multimodality management. In this retrospective study, we evaluated treatment outcomes of hypofractionated stereotactic radiotherapy (HFSRT) in the management of recurrent GBM and report our single-center experience. Twenty-eight patients receiving HFSRT for recurrent GBM between September 2008 and February 2014 were retrospectively assessed. Total radiotherapy dose was 25 Gy delivered in 5 fractions over 5 consecutive days for all patients. High-precision, image-guided volumetric modulated arc therapy was delivered with a linear accelerator using 6-MV photons using the frameless technique. Analyzed prognostic factors were age, gender, Karnofsky performance status (KPS), tumor location, planning target volume (PTV) size, overall survival (OS), progression-free survival (PFS), time interval between completion of treatment with Stupp protocol at primary diagnosis and recurrence. Median follow-up time was 42 months (range 2-68). Median time interval between primary chemoradiotherapy and HFSRT was 11.2 months (range 4-57.9). Median OS and PFS calculated from reirradiation was 10.3 months and 5.8 months, respectively. Longer interval between initial treatment and recurrence (p = 0.01), smaller PTV size (p = 0.001), KPS ≥70 (p = 0.005) and younger age (p = 0.004) were associated with longer OS on statistical analysis. HFSRT offers a feasible and effective salvage treatment option for recurrent GBM management. Prognostic factors associated with longer OS in our study were longer interval between initial treatment and recurrence, smaller PTV size, KPS ≥70 and younger age.

NI-51 * STEREOTACTIC ROBOT-GUIDED BIOPSIES OF BRAIN LESIONS: EXPERIENCE WITH 4 CASES

BACKGROUND AND PURPOSE: Biopsies of brain lesions are useful for histopathological analysis, which guide appropriate treatment. For the past few years, a frameless stereotactic robot, the NeuroMate robot (Renishaw, UK) has also been used for brain biopsies. We report a retrospective study of 4 patients who underwent NeuroMate robot-guided biopsies of brain lesions to evaluate the efficiency and safety of the system. METHODS: From January 2014 to March 2014, 4 adult patients underwent 4 biopsies of supratentorial brain lesions. The biopsy procedure comprised four stages: image acquisition, preoperative planning, patient-to-image registration, and operative procedure. A single burr hole was the entry point of each patient. RESULTS: All biopsies were positive for histopathological diagnosis from the first trial. All biopsies correlated precisely to preoperative biopsy planning. There was no operative mortality or morbidity. CONCLUSIONS: The frameless NeuroMate robot is an efficient and safe instrument for biopsies of brain lesions. We believe that the use of frameless stereotactic techniques for brain biopsies could increase the number of biopsies and therefore improve the diagnostic yield and accuracy of the technique.

Outcomes From First 3 Years of Frameless Stereotactic Radiosurgery in Treating Brain Metastases: Supportive Care/Palliation/Nursing

Stereotactic radiosurgery (SRS) is an important tool in management of brain metastases. Frameless SRS uses image guidance to deliver high dose radiation to the target volume, while being minimally invasive. Frameless techniques have improved patient comfort and allow flexibility in scheduling radiosurgery delivery. Previous case series have low patient numbers or short follow-up. In this study we report clinical outcomes and our center's experience with SRS in treating newly diagnosed brain metastases.

Targeting Accuracy of a Stereotactic Frameless Radiosurgery Technique for Arteriovenous Malformation

Targeting Accuracy of a Stereotactic Frameless Radiosurgery Technique for Arteriovenous Malformation

Frameless stereotactic drilling for placement of depth electrodes in refractory epilepsy: operative technique and initial experience.

For stereotactic implantation of depth electrodes in refractory epilepsy, both frame-based and frameless techniques have been developed. The higher versatility of current frameless techniques compared with framed-based methods is paid by the need of a standard burr hole for the implantation of 1 electrode. To develop a frameless method that allows convenient implantation of the electrode via a percutaneous bolt as used in frame-based methods, thereby avoiding the need for a standard burr hole. We adopted our technique from frameless stereotactic biopsy and designed the GIDE, a bone-fixated Guide for Implantation of Depth Electrodes. This reducing sleeve works as a stabilizer of the neuronavigation arm through bony contact and allows percutaneous stereotactic drilling, screwing of an implantation bolt, and placement of the depth electrode. Twenty-six electrodes in 7 patients (5 male and 2 female patients; median age, 19.6 years; range, 5.5-39.1 years) were successfully implanted. The overall accuracy was comparable to that of frameless stereotactic biopsy with a target deviation of 3.0±1.9 mm (mean±SD). All electrodes were within or touched the targeted anatomic structure with an adequate quality of the recordings. We encountered no hemorrhage or neurological deficit related to the depth electrode. Our technique combines the high versatility of frameless stereotaxy with the convenient implantation and fixation of the depth electrode via a percutaneous bolt used in frame-based stereotactic methods. Thus, our technique allows fast, efficient implantation of depth electrodes for intracranial electroencephalography recordings.

Frameless Nonstereotactic Image-Guided Surgery of Supratentorial Lesions: Introduction to a Safe and Inexpensive Technique

We describe a simple, safe, and inexpensive technique that through the comparison of three-dimensional (3D)-rendered magnetic resonance (MR) images and real anatomy allows us to navigate and remove brain lesions, including those without cortical appearance, by direct recognition of anatomical landmarks. Preoperative planning no longer requires the use of fiducials and can therefore be performed out a stereotactic setting. MR Digital Imaging and Communications in Medicine format scans of 93 patients were reconstructed using MRIcro freeware for their three-dimensional rendering (3DR). The main location of the lesions was rolandic or left temporal, and most of them were without cortical appearance (78%). The two-dimensional (2D) sets of images were processed by the software to perform a 3DR, thus obtaining a virtual model of the patient's head. Using the same 2D sets, the edges of the lesion's images were contoured by the region of interest (ROI) tool. In the next step, the ROI was projected onto the surface of the virtual model of the patient's head, thus helping to attain the best identification of the craniotomy area. MRIcro automatic segmentation function, the Brain Extraction Tool (BET), provides a clear 3DR of the cortical surface. We used BET to display gyri, sulci, and perilesional vessels to have further anatomical landmarks to guide the surgical approach. The lesions were accessed through an optimally suited craniotomy. The visual matching of the cortical surface with reconstructed 3D images of the cortex permitted a fast localization of cortical and subcortical lesions. The major limitation is the depth of a lesion deeper than 3 cm. In these cases, the use of frame-based or frameless techniques still seems safer and more advantageous. Conclusions: The shape recognition of the cortical landmarks was not biased by brain distortion because the sulci and cortical vessels almost always had a relationship to each other that was not modified by edema or cerebrospinal fluid leakage. This 3DR allows us to reconstruct a virtual anatomy in an easy, portable, and inexpensive way. In selected cases, this technique represents a valid and safe alternative to the use of costly neuronavigation tools and is potentially helpful in developing countries.

Досвід використання стереотаксичної техніки при хірургічному лікуванні кістозних вогнищевих утворень головного мозку

Вступ. Внутрішньомозкові кістозні вогнищеві утворення — ідеальна мішень для стереотаксичних втручань. Стереотаксична техніка при пункції та біопсії кістозних утворень головного мозку витісняє традиційні підходи до лікування цієї складної патології.Матеріали і методи. Матеріал дослідження — 24 хворі з кістозними вогнищевими утвореннями супратенторіальної локалізації, оперовані у клініці з 2009 по 2013 рік. Стереотаксичний супровід із використанням навігаційної системи Stealth Station® Treon® Plus фірми Medtroniс (США) та стереотаксичної системи Zamorano — Dujovny. Результати. Було проведено 20 втручань із використанням безрамної стереотаксичної техніки та 4 втручання з використанням рамного стереотаксису. Хворі були розподілені за діагнозами: абсцес головного мозку — 10, краніофарингеома — 5, анапластична астроцитома — 3, метастаз — 2, гематома — 2, анапластична епендимома — 1, астроцитома 2 ст. зл. — 1.Висновки. Лікування вогнищевих утворень головного мозку з використанням стереотаксичної техніки — сучасний, безпечний та ефективний вид хірургічного втручання.

TH-A-137-06: Development of a 4DOF Robotic Frameless SRS System for Both Translational and Rotational Head Motion Cancellation

Purpose: Frameless techniques have not been able to match or achieve spatial target accuracies better than traditional frame based SRS. This is due to the fact that decreased invasiveness will lead to decreased accuracy. Here, relaxation of the immobilization parameter by replacement of the head ring (strong immobilization) with a more comfortable immobilization device (weak immobilization) will lead to expression of a patient's natural intrinsic small sub‐millimeter involuntary motions. Current frameless techniques do not offer a means for correcting this intrinsic motion. To address this issue, we propose a novel non‐immobilization SRS approach based on continuous cancellation of a patient's intrinsic head motion throughout the radiation delivery process. The work presents for the first time a system where both translational (XYZ) and rotational (pitch) head motion cancellation is performed. Methods: A 4D (xyz+pitch) robotic motion cancellation device was constructed using 4 stepper motors and a 4 axis motor controller (PCI‐7344, National Instruments). Real‐time 6D head motion was optically monitored using either IR markers (Polaris, NDI) or a 3D surface camera (AlignRT, VisionRT). The measured head motion was inputted into a Labview algorithm based on a proportional‐integrative‐derivative (PID) controller used to guide the motors for performing real‐time head motion cancellation. Results: The real‐time (15 fps) 6D head motion of a human volunteer was monitored with and without the use of robotic cancellation. For all axes where motion cancellation was applied (XYZ+pitch), the mean translational and rotational motion never exceeded 0.001mm and 0.01deg., respectively (essentially reduced to small fluctuations around zero). Without cancellation, this increased to 0.8mm and 0.4deg., respectively. Conclusion: It is found that substantial reductions in both translational and rotational head motion can be realized through real‐time robotic motion cancellation. This has potential to allow frameless SRS to be performed at accuracies equal or greater than frame based SRS.

Frameless radiosurgery: Less invasive, more accurate

Purpose Stereotactic radiosurgery using frame-based positioning is a well-established technique for treatment of benign and malignant lesions. By contrast, a new trend towards frameless systems using image-guided techniques is gaining acceptance. This study was designed to compare the overall accuracy of frameless with framebased radiosurgery, to evaluate immobilization characteristics (i.e. intrafraction motion) of a frameless mask device to invasive fixation (frame-based technique) and to evaluate if verification images during radiosurgery treatment can correct for mechanical inaccuracy of table rotations and intrafraction motion. Materials and methods Multiple hidden target tests (HTT) were performed to measure the overall accuracy of the two positioning techniques for radiosurgery (i.e. frameless using stereoscopic X-ray imaging and 6-degree-of-freedom (DOF) registration/positioning and frame-based using invasive ring and localizer box) and to measure the overall accuracy at different table rotations with and without 6 DOF registration/positioning. Forty patients with 66 brain metastases were enrolled for frameless radiosurgery using 6 DOF registration/positioning. Positioning results were collected before and after treatment to assess intrafraction motion. Obtained data was benchmarked to literature for comparison with frame-based technique. Sixteen trigeminal-neuralgia patients were enrolled to assess positioning errors after every table position. Stereoscopic verification images and 6 DOF registration/positioning were performed and analyzed after each table rotation. Results HTT showed overall three-dimensional (3D) accuracy of 0.76 mm (SD0.46 mm) for the frameless technique, 0.87 mm (SD0.44 mm) for the frame-based technique for table positions at 0°. Rotating the couch to 90° and 270°, showed deviations of 0.83 mm (SD0.34 mm) and 0.62 mm (SD0.16 mm), respectively, if uncorrected. These deviations were reduced to 0.04 mm (SD0.03 mm) and 0.06 mm (SD0.04 mm) by image-guided corrections at 90° and 270°. The mean 3D intrafraction shift was 0.58 (SD0.42 mm) and comparable to frame-based techniques. By applying verification images during treatment (every 4.6 min SD 2.3 min), the mean 3D intrafraction shift decreased to 0.51 mm (SD0.13 mm). Conclusions With proper immobilization and X-ray verification images during treatment, frameless radiosurgery can be delivered as accurate as the frame-based approach with comparable immobilization characteristics to the invasive head ring and can be considered to be a reliable alternative for radiosurgery treatments. Stereotactic radiosurgery using frame-based positioning is a well-established technique for treatment of benign and malignant lesions. By contrast, a new trend towards frameless systems using image-guided techniques is gaining acceptance. This study was designed to compare the overall accuracy of frameless with framebased radiosurgery, to evaluate immobilization characteristics (i.e. intrafraction motion) of a frameless mask device to invasive fixation (frame-based technique) and to evaluate if verification images during radiosurgery treatment can correct for mechanical inaccuracy of table rotations and intrafraction motion. Multiple hidden target tests (HTT) were performed to measure the overall accuracy of the two positioning techniques for radiosurgery (i.e. frameless using stereoscopic X-ray imaging and 6-degree-of-freedom (DOF) registration/positioning and frame-based using invasive ring and localizer box) and to measure the overall accuracy at different table rotations with and without 6 DOF registration/positioning. Forty patients with 66 brain metastases were enrolled for frameless radiosurgery using 6 DOF registration/positioning. Positioning results were collected before and after treatment to assess intrafraction motion. Obtained data was benchmarked to literature for comparison with frame-based technique. Sixteen trigeminal-neuralgia patients were enrolled to assess positioning errors after every table position. Stereoscopic verification images and 6 DOF registration/positioning were performed and analyzed after each table rotation. HTT showed overall three-dimensional (3D) accuracy of 0.76 mm (SD0.46 mm) for the frameless technique, 0.87 mm (SD0.44 mm) for the frame-based technique for table positions at 0°. Rotating the couch to 90° and 270°, showed deviations of 0.83 mm (SD0.34 mm) and 0.62 mm (SD0.16 mm), respectively, if uncorrected. These deviations were reduced to 0.04 mm (SD0.03 mm) and 0.06 mm (SD0.04 mm) by image-guided corrections at 90° and 270°. The mean 3D intrafraction shift was 0.58 (SD0.42 mm) and comparable to frame-based techniques. By applying verification images during treatment (every 4.6 min SD 2.3 min), the mean 3D intrafraction shift decreased to 0.51 mm (SD0.13 mm). With proper immobilization and X-ray verification images during treatment, frameless radiosurgery can be delivered as accurate as the frame-based approach with comparable immobilization characteristics to the invasive head ring and can be considered to be a reliable alternative for radiosurgery treatments.

Frameless linac-based stereotactic radiosurgery treatment for SUNCT syndrome targeting the trigeminal nerve and sphenopalatine ganglion

The short-lasting unilateral neuralgiform headache associated with conjunctival injection and tearing or SUNCT syndrome was first described in the 1970s. This paper is the first in the literature that describes the successful use of stereotactic radiosurgery (SRS) using a non-invasive frameless technique, targeting both the trigeminal nerve and the sphenopalatine ganglion in the management of intractable SUNCT. We also discuss the role of selecting peripheral targets in the management of this rare headache syndrome. Among patients treated for functional pain disorders in our radiosurgery unit using the frameless technique since August 2011, one patient with symptoms matching the International Classification of Headache Disorders-2 (ICHD-II) criteria of SUNCT syndrome was identified. The multi-disciplinary case records of this patient were retrospectively reviewed and reported. Our patient had symptoms resembling the ICHD-II diagnostic criteria of SUNCT, which was refractory to medical treatment. Ninety Gy was delivered to the trigeminal root entry zone and 80 Gy was delivered to the sphenopalatine ganglion. At 16 months' follow-up, she was pain free with minimal side effects. Frameless linear accelerator (linac)-based SRS targeting the trigeminal nerve and sphenopalatine ganglion remained successful in our patient at 16 months. Longer follow-up and further experience will determine the efficacy and safety of this approach. We suggest that frameless SRS is a convenient and attractive non-invasive option for patients with medically refractory SUNCT.

Frame-based radiosurgery: Is it relevant in the era of IGRT?

To assess the setup errors and intrafraction motion in patients treated with frame-based and frameless stereotactic radiosurgery (SRS). Ten patients treated with frame-based and six patients treated with frameless radiosurgery were prospectively enrolled in the study. Leksell frame was used for frame-based and a customized uniframe orfit cast for frameless techniques. Cone beam computed tomography (CBCT) scans were taken immediately before and after each treatment to evaluate the positional accuracy and corrections applied with the use of hexapod couch for both groups. The mean translational shifts with frame-based SRS were 1.00 ± 0.30 mm in the lateral direction (X), 0.20 ± 1.20 mm in craniocaudal direction (Y) and -0.10 ± 0.31 mm in the anteroposterior direction (Z). The rotational shifts for frame-based treatments were as follows: roll 0.32 ± 0.70, pitch 0.44 ± 0.66 and yaw 0.20 ± 0.4. For frameless SRS, translational shifts were -0.40 ± 0.90, 1.10 ± 1.10, and 0.50 ± 1.30 mm in X, Y, and Z directions, respectively, and rotational shifts were -0.11 ± 0.78, 0.20 ± 0.44, and 0.29 ± 0.35 in roll, pitch, and yaw, respectively. Intrafraction shifts with frame-based SRS were: X = 0.60 ± 1.80 mm, Y = 0.20 ± 0.60 mm, and Z = 0.00 ± 0.05 mm; and rotational shifts were: roll 0.01 ± 0.27, pitch 0.06 ± 0.15, and yaw 0.01 ± 0.09. For frameless SRS, these were: X = 0.11 ± 0.20 mm, Y = 0.20 ± 0.40 mm, and Z = 0.20 ± 0.20 mm and rotational shifts were: roll 0.09 ± 0.23, pitch 0.00 ± 0.12, and yaw 0.00 ± 0.09. In our experience, set up accuracy of frameless SRS is as good as frame-based SRS. With availability of verification methods such as CBCT and hexapod couch, an accurate and precise treatment delivery is feasible with frameless techniques.

A Frameless Stereotaxic MRI Technique for Macaque Neuroscience Studies

MRI has achieved widespread use for preplanning neuroscience procedures for non-human primate studies. However, orienting imaging studies in stereotaxic space has relied primarily on using a stereotaxic frame or co-registering fiducial markers with the neuroimaging. In this study, we present a simple approach in which the MRI dataset is aligned to the bony landmarks that define the Frankfurt stereotaxic baseline plane, without the need for a stereotaxic frame or additional external fiducials. To facilitate localizing the bony landmarks (infraorbital margin, external bony auditory meatus) on the MRI scans additional imaging landmarks (mid ocular plane, temporomandibular joint) are discussed that provide supplementary and readily visible points of reference. The frameless MRI stereotaxic technique was evaluated in 8 rhesus macaque monkeys using 3D fast gradient echo MRI images with 0.7mm isotropic resolution. 1) Difference in stereotaxic coordinates of fiducial markers was compared between a traditional stereotaxic frame and the frameless MRI technique (n=2). 2) Differences in stereotaxic coordinates for cerebral regions were compared between the frameless MRI technique and MRI obtained with the animal positioned in a MRI-compatible stereotaxic frame (n=4). 3) The frameless MRI technique was further refined to prescribe electrode penetrations within a dural recording chamber in stereotaxic coordinates relative to the electrode microdrive. Differences in MRI coordinates were compared with the electrode microdrive (n=3). Mean localization of fiducial markers differed by 1.6 +/- 0.6 mm between the frameless MRI technique and a traditional stereotaxic frame. Between the frameless technique and an MRI-compatible stereotaxic frame, localization of cerebral anatomy differed by 2.8 +/- 2.2 mm with the primary source of error being a pitch-up rotation in the sagittal plane. This localization difference was reduced to 0.5 +/- 0.6 mm when this rotation was removed. Frameless MRI coordinates for electrode tracts within the dural recording chamber were within 0.5mm +/- 0.2 mm of the electrode microdrive readings. This simple technique provides the ability to accurately plan surgery and neurophysiological recordings in an individual animal, and to define the location of cerebral anatomy and electrode or injection tracts using publically available software, and without the need for dedicated MRI-compatible localization hardware. The reduced need for deep anesthesia (a necessity with traditional stereotaxic frames) makes the technique more amenable for functional MRI studies. Since each animal provides the bony landmarks to define their own stereotaxic space, this technique is readily applicable to other species.

Current Dosing Paradigm For Stereotactic Radiosurgery Alone Following Surgical Resection of Brain Metastases Needs To Be Optimized For Improved Local Control

Current Dosing Paradigm For Stereotactic Radiosurgery Alone Following Surgical Resection of Brain Metastases Needs To Be Optimized For Improved Local Control