Functional stereotactic radiosurgery involving a dedicated linear accelerator and gamma unit: a comparison study

2004 ◽  
pp. 373-380 ◽  
Author(s):  
Timothy D. Solberg ◽  
Steven J. Goetsch ◽  
Michael T. Selch ◽  
William Melega ◽  
Goran Lacan ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Linear Accelerator ◽  
Treatment Plan ◽  
Single Shot ◽  
Submillimeter Range ◽  
Primate Model ◽  
Content Type ◽  
Stereotactic Frame ◽  
Targeting Ability ◽  
Fine Print

Object. The purpose of this work was to investigate the targeting and dosimetric characteristics of a linear accelerator (LINAC) system dedicated for stereotactic radiosurgery compared with those of a commercial gamma knife (GK) unit. Methods. A phantom was rigidly affixed within a Leksell stereotactic frame and axial computerized tomography scans were obtained using an appropriate stereotactic localization device. Treatment plans were performed, film was inserted into a recessed area, and the phantom was positioned and treated according to each treatment plan. In the case of the LINAC system, four 140° arcs, spanning ± 60° of couch rotation, were used. In the case of the GK unit, all 201 sources were left unplugged. Radiation was delivered using 3- and 8-mm LINAC collimators and 4- and 8-mm collimators of the GK unit. Targeting ability was investigated independently on the dedicated LINAC by using a primate model. Measured 50% spot widths for multisource, single-shot radiation exceeded nominal values in all cases by 38 to 70% for the GK unit and 11 to 33% for the LINAC system. Measured offsets were indicative of submillimeter targeting precision on both devices. In primate studies, the appearance of an magnetic resonance imaging—enhancing lesion coincided with the intended target. Conclusions. Radiosurgery performed using the 3-mm collimator of the dedicated LINAC exhibited characteristics that compared favorably with those of a dedicated GK unit. Overall targeting accuracy in the submillimeter range can be achieved, and dose distributions with sharp falloff can be expected for both devices.

Functional stereotactic radiosurgery involving a dedicated linear accelerator and gamma unit: a comparison study

2004 ◽  
Vol 101 (Supplement3) ◽  
pp. 373-380 ◽  
Author(s):  
Timothy D. Solberg ◽  
Steven J. Goetsch ◽  
Michael T. Selch ◽  
William Melega ◽  
Goran Lacan ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Linear Accelerator ◽  
Treatment Plan ◽  
Single Shot ◽  
Submillimeter Range ◽  
Primate Model ◽  
Content Type ◽  
Stereotactic Frame ◽  
Targeting Ability ◽  
Fine Print

Object. The purpose of this work was to investigate the targeting and dosimetric characteristics of a linear accelerator (LINAC) system dedicated for stereotactic radiosurgery compared with those of a commercial gamma knife (GK) unit. Methods. A phantom was rigidly affixed within a Leksell stereotactic frame and axial computerized tomography scans were obtained using an appropriate stereotactic localization device. Treatment plans were performed, film was inserted into a recessed area, and the phantom was positioned and treated according to each treatment plan. In the case of the LINAC system, four 140° arcs, spanning ± 60° of couch rotation, were used. In the case of the GK unit, all 201 sources were left unplugged. Radiation was delivered using 3- and 8-mm LINAC collimators and 4- and 8-mm collimators of the GK unit. Targeting ability was investigated independently on the dedicated LINAC by using a primate model. Measured 50% spot widths for multisource, single-shot radiation exceeded nominal values in all cases by 38 to 70% for the GK unit and 11 to 33% for the LINAC system. Measured offsets were indicative of submillimeter targeting precision on both devices. In primate studies, the appearance of an magnetic resonance imaging—enhancing lesion coincided with the intended target. Conclusions. Radiosurgery performed using the 3-mm collimator of the dedicated LINAC exhibited characteristics that compared favorably with those of a dedicated GK unit. Overall targeting accuracy in the submillimeter range can be achieved, and dose distributions with sharp falloff can be expected for both devices.

Preliminary results of linear accelerator radiosurgery for acoustic schwannomas

1996 ◽  
Vol 85 (6) ◽  
pp. 1013-1019 ◽  
Author(s):  
William M. Mendenhall ◽  
William A. Friedman ◽  
John M. Buatti ◽  
Francis J. Bova
Keyword(s):  
Stereotactic Radiosurgery ◽  
Local Control ◽  
Linear Accelerator ◽  
Local Control Rate ◽  
Magnetic Resonance Images ◽  
High Rate ◽  
Content Type ◽  
Treatment Volume ◽  
Fine Print

✓ In this paper the authors evaluate the results of linear accelerator (LINAC)—based stereotactic radiosurgery for acoustic schwannomas. Fifty-six patients underwent LINAC-based stereotactic radiosurgery for acoustic schwannomas at the University of Florida between July 1988 and November 1994. Each patient was followed for a minimum of 1 year or until death; no patient was lost to follow up. One or more follow-up magnetic resonance images or computerized tomography scans were obtained in 52 of the 56 patients. Doses ranged between 10 and 22.5 Gy with 69.6% of patients receiving 12.5 to 15 Gy. Thirty-eight patients (68%) were treated with one isocenter and the dose was specified to the 80% isodose line in 71% of patients. Fifty-five patients (98%) achieved local control after treatment. The 5-year actuarial local control rate was 95%. At the time of analysis, 48 patients were alive and free of disease, seven had died of intercurrent disease, and one was alive with disease. Complications developed in 13 patients (23%). The likelihood of complications was related to the dose and treatment volume: 10 to 12.5 Gy to all volumes, three (13%) of 23 patients; 15 to 17.5 Gy to 5.5 cm3 or less, two (9%) of 23 patients; 15 to 17.5 Gy to more than 5.5 cm3, five (71%) of seven patients; and 20 to 22.5 Gy to all volumes, three (100%) of three patients. Linear accelerator—based stereotactic radiosurgery results in a high rate of local control at 5 years. The risk of complications is related to the dose and treatment volume.

Safety and efficacy of stereotactic radiosurgery for tumors of the spine

2004 ◽  
pp. 413-418 ◽  
Author(s):  
Deborah L. Benzil ◽  
Mehran Saboori ◽  
Alon Y. Mogilner ◽  
Ronald Rocchio ◽  
Chitti R. Moorthy
Keyword(s):  
Spinal Cord ◽  
Single Dose ◽  
Pain Relief ◽  
Total Dose ◽  
Stereotactic Radiosurgery ◽  
Medical Center ◽  
Primary Tumors ◽  
Content Type ◽  
Increased Risk ◽  
Fine Print

Object. The extension of stereotactic radiosurgery treatment of tumors of the spine has the potential to benefit many patients. As in the early days of cranial stereotactic radiosurgery, however, dose-related efficacy and toxicity are not well understood. The authors report their initial experience with stereotactic radiosurgery of the spine with attention to dose, efficacy, and toxicity. Methods. All patients who underwent stereotactic radiosurgery of the spine were treated using the Novalis unit at Westchester Medical Center between December 2001 and January 2004 are included in a database consisting of demographics on disease, dose, outcome, and complications. A total of 31 patients (12 men, 19 women; mean age 61 years, median age 63 years) received treatment for 35 tumors. Tumor types included 26 metastases (12 lung, nine breast, five other) and nine primary tumors (four intradural, five extradural). Thoracic tumors were most common (17 metastases and four primary) followed by lumbar tumors (four metastases and four primary). Lesions were treated to the 85 to 90% isodose line with spinal cord doses being less than 50%. The dose per fraction and total dose were selected on the basis of previous treatment (particularly radiation exposure), size of lesion, and proximity to critical structures. Conclusions. Rapid and significant pain relief was achieved after stereotactic radiosurgery in 32 of 34 treated tumors. In patients treated for metastases, pain was relieved within 72 hours and remained reduced 3 months later. Pain relief was achieved with a single dose as low as 500 cGy. Spinal cord isodoses were less than 50% in all patients except those with intradural tumors (mean single dose to spinal cord 268 cGy and mean total dose to spinal cord 689 cGy). Two patients experienced transient radiculitis (both with a biological equivalent dose (BED) > 60 Gy). One patient who suffered multiple recurrences of a conus ependymoma had permanent neurological deterioration after initial improvement. Pathological evaluation of this lesion at surgery revealed radiation necrosis with some residual/recurrent tumor. No patient experienced other organ toxicity. Stereotactic radiosurgery of the spine is safe at the doses used and provides effective pain relief. In this study, BEDs greater than 60 Gy were associated with an increased risk of radiculitis.

Geometrical accuracy of the Novalis stereotactic radiosurgery system for trigeminal neuralgia

2004 ◽  
Vol 101 (Supplement3) ◽  
pp. 351-355 ◽  
Author(s):  
Javad Rahimian ◽  
Joseph C. Chen ◽  
Ajay A. Rao ◽  
Michael R. Girvigian ◽  
Michael J. Miller ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Trigeminal Neuralgia ◽  
Image Fusion ◽  
Stereotactic Radiosurgery ◽  
Ct Images ◽  
Radiochromic Film ◽  
Quality Assurance Program ◽  
Content Type ◽  
Geometrical Accuracy ◽  
Fine Print

Object. Stringent geometrical accuracy and precision are required in the stereotactic radiosurgical treatment of patients. Accurate targeting is especially important when treating a patient in a single fraction of a very high radiation dose (90 Gy) to a small target such as that used in the treatment of trigeminal neuralgia (3 to 4—mm diameter). The purpose of this study was to determine the inaccuracies in each step of the procedure including imaging, fusion, treatment planning, and finally the treatment. The authors implemented a detailed quality-assurance program. Methods. Overall geometrical accuracy of the Novalis stereotactic system was evaluated using a Radionics Geometric Phantom Chamber. The phantom has several magnetic resonance (MR) and computerized tomography (CT) imaging—friendly objects of various shapes and sizes. Axial 1-mm-thick MR and CT images of the phantom were acquired using a T1-weighted three-dimensional spoiled gradient recalled pulse sequence and the CT scanning protocols used clinically in patients. The absolute errors due to MR image distortion, CT scan resolution, and the image fusion inaccuracies were measured knowing the exact physical dimensions of the objects in the phantom. The isocentric accuracy of the Novalis gantry and the patient support system was measured using the Winston—Lutz test. Because inaccuracies are cumulative, to calculate the system's overall spatial accuracy, the root mean square (RMS) of all the errors was calculated. To validate the accuracy of the technique, a 1.5-mm-diameter spherical marker taped on top of a radiochromic film was fixed parallel to the x–z plane of the stereotactic coordinate system inside the phantom. The marker was defined as a target on the CT images, and seven noncoplanar circular arcs were used to treat the target on the film. The calculated system RMS value was then correlated with the position of the target and the highest density on the radiochromic film. The mean spatial errors due to image fusion and MR imaging were 0.41 ± 0.3 and 0.22 ± 0.1 mm, respectively. Gantry and couch isocentricities were 0.3 ± 0.1 and 0.6 ± 0.15 mm, respectively. The system overall RMS values were 0.9 and 0.6 mm with and without the couch errors included, respectively (isocenter variations due to couch rotation are microadjusted between couch positions). The positional verification of the marker was within 0.7 ± 0.1 mm of the highest optical density on the radiochromic film, correlating well with the system's overall RMS value. The overall mean system deviation was 0.32 ± 0.42 mm. Conclusions. The highest spatial errors were caused by image fusion and gantry rotation. A comprehensive quality-assurance program was developed for the authors' stereotactic radiosurgery program that includes medical imaging, linear accelerator mechanical isocentricity, and treatment delivery. For a successful treatment of trigeminal neuralgia with a 4-mm cone, the overall RMS value of equal to or less than 1 mm must be guaranteed.

Dose—response tolerance of the visual pathways and cranial nerves of the cavernous sinus to stereotactic radiosurgery

1998 ◽  
Vol 88 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Klaus A. Leber ◽  
Jutta Berglöff ◽  
Gerhard Pendl
Keyword(s):  
Stereotactic Radiosurgery ◽  
Cavernous Sinus ◽  
Dose Response ◽  
Cranial Nerves ◽  
Visual Pathways ◽  
Content Type ◽  
Number Of Patients ◽  
Response Tolerance ◽  
Fine Print

As the number of patients treated with stereotactic radiosurgery increases, it becomes particularly important to define with precision adverse effects on distinct structures of the nervous system. Object. This study was designed to assess the dose—response tolerance of the visual pathways and cranial nerves after exposure of the cavernous sinus to radiation. Methods. A total of 66 sites in the visual system and 210 cranial nerves of the middle cranial fossa were investigated in 50 patients who had undergone gamma knife treatment for benign skull base tumors. The mean follow-up period was 40 months (range 24–60 months). Follow-up examinations consisted of neurological, neuroradiological, and neuroophthalmological evaluations. The actuarial incidence of optic neuropathy was zero for patients who received a radiation dose of less than 10 Gy, 26.7% for patients receiving a dose in the range of 10 to less than 15 Gy, and 77.8% for those who received doses of 15 Gy or more (p < 0.0001). Previously impaired vision improved in 25.8% and was unchanged in 51.5% of patients. No sign of neuropathy was seen in patients whose cranial nerves of the cavernous sinus received radiation doses of between 5 and 30 Gy. Because tumor control appeared to have been achieved in 98% of the patients, the deterioration in visual function cannot be attributed to tumor progression. Conclusions. The structures of the visual pathways (the optic nerve, chiasm, and tract) exhibit a much higher sensitivity to single-fraction radiation than other cranial nerves, and their particular dose—response characteristics can be defined. In contrast, the oculomotor and trigeminal nerves have a much higher dose tolerance.

Safety and efficacy of stereotactic radiosurgery for tumors of the spine

2004 ◽  
Vol 101 (Supplement3) ◽  
pp. 413-418 ◽  
Author(s):  
Deborah L. Benzil ◽  
Mehran Saboori ◽  
Alon Y. Mogilner ◽  
Ronald Rocchio ◽  
Chitti R. Moorthy
Keyword(s):  
Spinal Cord ◽  
Single Dose ◽  
Pain Relief ◽  
Total Dose ◽  
Stereotactic Radiosurgery ◽  
Medical Center ◽  
Primary Tumors ◽  
Content Type ◽  
Increased Risk ◽  
Fine Print

Object. The extension of stereotactic radiosurgery treatment of tumors of the spine has the potential to benefit many patients. As in the early days of cranial stereotactic radiosurgery, however, dose-related efficacy and toxicity are not well understood. The authors report their initial experience with stereotactic radiosurgery of the spine with attention to dose, efficacy, and toxicity. Methods. All patients who underwent stereotactic radiosurgery of the spine were treated using the Novalis unit at Westchester Medical Center between December 2001 and January 2004 are included in a database consisting of demographics on disease, dose, outcome, and complications. A total of 31 patients (12 men, 19 women; mean age 61 years, median age 63 years) received treatment for 35 tumors. Tumor types included 26 metastases (12 lung, nine breast, five other) and nine primary tumors (four intradural, five extradural). Thoracic tumors were most common (17 metastases and four primary) followed by lumbar tumors (four metastases and four primary). Lesions were treated to the 85 to 90% isodose line with spinal cord doses being less than 50%. The dose per fraction and total dose were selected on the basis of previous treatment (particularly radiation exposure), size of lesion, and proximity to critical structures. Conclusions. Rapid and significant pain relief was achieved after stereotactic radiosurgery in 32 of 34 treated tumors. In patients treated for metastases, pain was relieved within 72 hours and remained reduced 3 months later. Pain relief was achieved with a single dose as low as 500 cGy. Spinal cord isodoses were less than 50% in all patients except those with intradural tumors (mean single dose to spinal cord 268 cGy and mean total dose to spinal cord 689 cGy). Two patients experienced transient radiculitis (both with a biological equivalent dose (BED) > 60 Gy). One patient who suffered multiple recurrences of a conus ependymoma had permanent neurological deterioration after initial improvement. Pathological evaluation of this lesion at surgery revealed radiation necrosis with some residual/recurrent tumor. No patient experienced other organ toxicity. Stereotactic radiosurgery of the spine is safe at the doses used and provides effective pain relief. In this study, BEDs greater than 60 Gy were associated with an increased risk of radiculitis.

Results of combined stereotactic radiosurgery and transarterial embolization for dural arteriovenous fistulas of the transverse and sigmoid sinuses

2001 ◽  
Vol 94 (6) ◽  
pp. 886-891 ◽  
Author(s):  
Jonathan A. Friedman ◽  
Bruce E. Pollock ◽  
Douglas A. Nichols ◽  
Deborah A. Gorman ◽  
Robert L. Foote ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Transarterial Embolization ◽  
Symptom Relief ◽  
Related Complication ◽  
Content Type ◽  
Arteriovenous Fistulas ◽  
Dural Arteriovenous Fistulas ◽  
Lost To Follow Up ◽  
Fine Print

Object. Most dural arteriovenous fistulas (DAVFs) of the transverse and sigmoid sinuses do not have angiographically demonstrated features associated with intracranial hemorrhage and, therefore, may be treated nonsurgically. The authors report their experience using a staged combination of radiosurgery and transarterial embolization for treating DAVFs involving the transverse and sigmoid sinuses. Methods. Between 1991 and 1998, 25 patients with DAVFs of the transverse and/or sigmoid sinuses were treated using stereotactic radiosurgery; 22 of these patients also underwent transarterial embolization. Two patients were lost to follow-up review. Clinical data, angiographic findings, and follow-up records for the remaining 23 patients were collected prospectively. The mean duration of clinical follow up after radiosurgery was 50 months (range 20–99 months). The 18 women and five men included in this series had a mean age of 57 years (range 33–79 years). Twenty-two (96%) of 23 patients presented with pulsatile tinnitus as the primary symptom; two patients had experienced an earlier intracerebral hemorrhage (ICH). Cognard classifications of the DAVFs included the following: I in 12 patients (52%), IIa in seven patients (30%), and III in four patients (17%). After treatment, symptoms resolved (20 patients) or improved significantly (two patients) in 96% of patients. One patient was clinically unchanged. No patient sustained an ICH or irradiation-related complication during the follow-up period. Seventeen patients underwent follow-up angiographic studies at a mean of 21 months after radiosurgery (range 11–38 months). Total or near-total obliteration (> 90%) was seen in 11 patients (65%), and more than a 50% reduction in six patients (35%). Two patients experienced recurrent tinnitus and underwent repeated radiosurgery and embolization at 21 and 38 months, respectively, after the first procedure. Conclusions. A staged combination of radiosurgery and transarterial embolization provides excellent symptom relief and a good angiographically verified cure rate for patients harboring low-risk DAVFs of the transverse and sigmoid sinuses. This combined approach is a safe and effective treatment strategy for patients without angiographically determined risk factors for hemorrhage and for elderly patients with significant comorbidities.

Linear accelerator radiosurgery for vestibular schwannoma

2001 ◽  
Vol 94 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Roberto Spiegelmann ◽  
Zvi Lidar ◽  
Jana Gofman ◽  
Dror Alezra ◽  
Moshe Hadani ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Gamma Knife ◽  
Linear Accelerator ◽  
Imaging Modality ◽  
Gamma Knife Radiosurgery ◽  
Cranial Neuropathy ◽  
Content Type ◽  
Linac Radiosurgery ◽  
Acoustic Neuromas ◽  
Fine Print

Object. The use of radiosurgery in the treatment of acoustic neuromas has increased substantially during the last decade. Most published experience relates to the use of the gamma knife. In this report, the authors review the methods and results of linear accelerator (LINAC) radiosurgery in 44 patients with acoustic neuromas who were treated between 1993 and 1997. Methods. Computerized tomography scanning was selected as the stereotactic imaging modality for target definition. A single, conformally shaped isocenter was used in the treatment of 40 patients; two or three isocenters were used in four patients who harbored very irregular tumors. The radiation dose directed to the tumor border was the only parameter that changed during the study period: in the first 24 patients who were treated the dose was 15 to 20 Gy, whereas in the last 20 patients the dose was reduced to 11 to 14 Gy. After a mean follow-up period of 32 months (range 12–60 months), 98% of the tumors were controlled. The actuarial hearing preservation rate was 71%. New transient facial neuropathy developed in 24% of the patients and persisted to a mild degree in 8%. Radiation dose correlated significantly with the incidence of cranial neuropathy, particularly in large tumors (≥ 4 cm3). Conclusions. Single-isocenter LINAC radiosurgery proved to be an effective treatment for acoustic neuromas in this series, with results that were comparable with those reported for gamma knife radiosurgery and multiple isocenters.

Three-dimensional angiography for radiosurgical treatment planning for arteriovenous malformations

2003 ◽  
Vol 98 (3) ◽  
pp. 536-543 ◽  
Author(s):  
Federico Colombo ◽  
Carlo Cavedon ◽  
Paolo Francescon ◽  
Leopoldo Casentini ◽  
Umberto Fornezza ◽  
...  
Keyword(s):  
Treatment Planning ◽  
Imaging Modality ◽  
Treatment Plan ◽  
Three Dimensional ◽  
Ct Scanning ◽  
New Method ◽  
Rotational Angiography ◽  
Content Type ◽  
3D Rotational Angiography ◽  
Fine Print

Object. Radiosurgical treatment of a cerebral arteriovenous malformation (AVM) requires the precise definition of the nidus of the lesion in stereotactic space. This cannot be accomplished using simple stereotactic angiography, but requires a combination of stereotactic biplanar angiographic images and stereotactic contrast-enhanced computerized tomography (CT) scans. In the present study the authors describe a method in which three-dimensional (3D) rotational angiography is integrated into stereotactic space to aid treatment planning for radiosurgery. Methods. Twenty patients harboring AVMs underwent treatment planning prior to linear accelerator radiosurgery. Planning involved the acquisition of two different data sets, one of which was obtained using the standard method (a combination of biplanar stereotactic angiography with stereotactic CT scanning), and the other, which was procured using a new technique (nonstereotactic 3D rotational angiography combined with stereotactic CT scanning by a procedure of image fusion). The treatment plan that was developed using the new method was compared with that developed using the standard one. For each patient the number of isocenters and the dimension of selected collimators were the same, based on the information supplied in both methods. Target coordinates were modified in only five cases and by a limited amount (mean 0.7 mm, range 0.3–1 mm). Conclusions. The new imaging modality offers an easier and more immediate interpretation of 3D data, while maintaining the same accuracy in target definition as that provided by the standard technique. Moreover, the new method has the advantage of using nonstereotactic 3D angiography, which can be performed at a different site and a different time with respect to the irradiation procedure.

Brain biopsy sampling by using prospective stereotaxis and a trajectory guide

2001 ◽  
Vol 94 (1) ◽  
pp. 67-71 ◽  
Author(s):  
Walter A. Hall ◽  
Haiying Liu ◽  
Alastair J. Martin ◽  
Robert E. MAxwell ◽  
Charles L. Truwit
Keyword(s):  
Frozen Section ◽  
Spin Echo ◽  
Brain Biopsy ◽  
Pathological Examination ◽  
Single Shot ◽  
Biopsy Needle ◽  
Content Type ◽  
Postoperative Myocardial Infarction ◽  
Clinically Significant ◽  
Fine Print

Object. The authors describe their initial results obtained using a skull-mounted trajectory guide for intraoperative magnetic resonance (MR) imaging—guided brain biopsy sampling. The device was used in conjunction with a new methodology known as prospective stereotaxis for surgical trajectory alignment. Methods. Between January 1999 and March 2000, 38 patients underwent 40 brain biopsy procedures in which prospective stereotaxis was performed with the trajectory guide in a short-bore 1.5-tesla MR imager. In most cases, orthogonal T2-weighted half-Fourier acquisition single-shot turbo spin—echo (HASTE) images were used to determine the desired trajectory and align the device. The surgical trajectory was defined as a line connecting three points: the target, pivot, and alignment stem points. In all cases, surgical specimens were submitted for frozen section and pathological examination. Postoperative turbofluid-attenuated inversion-recovery and gradient-echo images were obtained to exclude the presence of hemorrhage. Trajectory determination and alignment was simple and efficient, requiring less than 5 minutes. Confirmatory HASTE images were obtained along the biopsy needle as it was being advanced or after reaching the target. All biopsy procedures yielded diagnostic tissue. One patient with a lesion near the motor strip experienced a transient hemiparesis of the hand related to passage of the biopsy needle, and another sustained a fatal postoperative myocardial infarction. No patient suffered a clinically significant or radiologically visible hemorrhage. Conclusions. In combination with prospective stereotaxis, the trajectory guide provided a safe and accurate way to perform brain biopsy procedures.

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