A comparison of the gamma knife model C and the Automatic Positioning System with Leksell model B

2005 ◽  
Vol 102 (Special_Supplement) ◽  
pp. 25-28 ◽  
Author(s):  
Daniela Tlachacova ◽  
Michal Schmitt ◽  
Josef Novotny ◽  
Josef Novotny ◽  
Mustafa Majali ◽  
...  
Keyword(s):  
Radiation Exposure ◽  
Gamma Knife ◽  
Positioning System ◽  
Content Type ◽  
Ocular Lesions ◽  
Significant Difference ◽  
Model C ◽  
Automatic Positioning ◽  
Fine Print

Object. The authors sought to compare the quality of treatment planning, radiation protection, and the time taken for treatment in the Leksell gamma knife model B with that using the model C Automatic Positioning System (APS). Methods. Data were obtained in 463 patients treated with the B model and 518 patients treated with the C model. Data were analyzed in patients in whom the following diagnoses had been made: vestibular schwannoma, pituitary adenoma, meningioma, solitary metastasis, and other benign and malignant solitary tumors. Patients with arteriovenous malformations, ocular lesions, and functional diagnoses were excluded from this study. Conclusions. With the C model there was a better conformity for most treated targets, such as vestibular schwannomas (p = 0.005) and meningiomas (p = 0.015). The level of radiation exposures to personnel was significantly decreased when using the model C (p < 0.001). There was no significant difference in radiation exposure of extracranial structures for the same number of shots in patients treated by both models. The mean time saved using the C model with the APS was 41 minutes per treatment. It would seem that the gamma knife model C permits better dose conformity, shorter treatment times, and less radiation exposure to personnel.

A comparison of the gamma knife model C and the Automatic Positioning System with Leksell model B

2005 ◽  
Vol 102 ◽  
pp. 25-28 ◽  
Author(s):  
Daniela Tlachacova ◽  
Michal Schmitt ◽  
Josef Novotny ◽  
Josef Novotny ◽  
Mustafa Majali ◽  
...  
Keyword(s):  
Radiation Exposure ◽  
Gamma Knife ◽  
Positioning System ◽  
Content Type ◽  
Ocular Lesions ◽  
Significant Difference ◽  
Model C ◽  
Automatic Positioning ◽  
Fine Print

Object.The authors sought to compare the quality of treatment planning, radiation protection, and the time taken for treatment in the Leksell gamma knife model B with that using the model C Automatic Positioning System (APS).Methods.Data were obtained in 463 patients treated with the B model and 518 patients treated with the C model. Data were analyzed in patients in whom the following diagnoses had been made: vestibular schwannoma, pituitary adenoma, meningioma, solitary metastasis, and other benign and malignant solitary tumors. Patients with arteriovenous malformations, ocular lesions, and functional diagnoses were excluded from this study.Conclusions.With the C model there was a better conformity for most treated targets, such as vestibular schwannomas (p = 0.005) and meningiomas (p = 0.015). The level of radiation exposures to personnel was significantly decreased when using the model C (p < 0.001). There was no significant difference in radiation exposure of extracranial structures for the same number of shots in patients treated by both models. The mean time saved using the C model with the APS was 41 minutes per treatment. It would seem that the gamma knife model C permits better dose conformity, shorter treatment times, and less radiation exposure to personnel.

Gamma knife model C with the automatic positioning system and its impact on the treatment of vestibular schwannomas

2002 ◽  
Vol 97 ◽  
pp. 450-455 ◽  
Author(s):  
Gerhard A. Horstmann ◽  
Albertus T. C. J. Van Eck
Keyword(s):  
Gamma Knife ◽  
Target Volume ◽  
Vestibular Schwannomas ◽  
Positioning System ◽  
Content Type ◽  
Loss Of Hearing ◽  
Model C ◽  
Automatic Positioning ◽  
Fine Print

Object. The aim of this study was to assess the effects of the gamma knife automatic positioning system (APS) on the treatment of patients, particularly effects of this system on the treatment of patients with vestibular schwannomas (VSs), with a view to reducing loss of hearing. Methods. The dose delivery with an increased number of shots was checked with GAFChromic Film for various numbers of shots (one to 129). The results in the first 549 patients were recorded. In addition a series of 59 patients with VSs treated with 13 Gy to the 65% isodose is presented. The authors have termed this the “13 on 65” concept. The film dosimetry showed that a large number of small shots did not materially affect the dose and dose distribution produced by gamma knife treatment. The APS was used alone in 72% of arteriovenous malformations, 71% of meningiomas, 94% of VSs, and 84% of pituitary adenomas. Metastatic tumors were accessible in a pure APS mode in 59% of all cases, glioma in 58%, and uveal melanoma in 10% of the cases. Thus two thirds of patients could be treated using APS alone. It was possible to use the APS and manual systems together for complex or very eccentrically placed targets. The APS resulted in the use of a larger number of isocenters. After a mean follow-up period of 15 months, the results in patients with the VSs in whom 13 Gy was delivered to the 65% isodose were similar to those in patients treated with the more conventional 50% margin isodose. There was no change in the incidence of hearing loss within the study period, and the incidence of trigeminal and facial neuropathies remained unchanged after treatment as well. Conclusions. The APS encourages the design of more conformal dose plans. The greater use of smaller collimators results in a steeper dose gradient with a smaller amount of radiation outside the target volume. Because the APS is able to apply a large number of smaller isocenters in an acceptable time, the number of isocenters used is increased. An increased number of isocenters can also be used to reduce the maximum radiation dose and increase the homogeneity in a given dose plan.

The commissioning and quality assurance of the Automatic Positioning System on the Leksell gamma knife

2002 ◽  
Vol 97 ◽  
pp. 574-578 ◽  
Author(s):  
Tracy Soanes ◽  
Anna Hampshire ◽  
Paul Vaughan ◽  
Christopher Brownett ◽  
Jeremy Rowe ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Base Plate ◽  
Positioning System ◽  
Positional Accuracy ◽  
Content Type ◽  
Test Tool ◽  
Test Treatments ◽  
Model C ◽  
Automatic Positioning ◽  
Fine Print

Object. The authors describe a series of commissioning checks that were developed following the installation of the Automatic Positioning System (APS) on the model C gamma knife. Methods. System reliability was checked by performing a series of test treatments using the APS. A phantom was designed to enable the exposure of small pieces of Gaf Chromic film at 40 different predefined x, y, and z coordinates. The phantom consisted of a base plate with a series of film holders to facilitate the exposures using a 4-mm field, the center of which was marked. A spreadsheet calculation was performed to verify the conversion from Leksell coordinates to the APS coordinates when the treatment angle (gamma angle) is other than 90°. A number of APS plans were prepared and the coordinate transformation verified. Precision measurements were performed to verify the correct positioning of the high bars when attached to the frame. The Gaf Chromic films were exposed, and the APS plans were used when confined to positions within the high bar range. A test tool to verify accurate location of the high bars on the frame was also designed. Conclusions. The performance of APS was verified independently of the manufacturer by using specially designed tools, phantoms, and spread sheets. At all points tested, the positional accuracy was found to be within specification. Conversion to APS coordinates was verified as correct.

Impact of the model C and Automatic Positioning System on gamma knife radiosurgery: an evaluation in vestibular schwannomas

2002 ◽  
Vol 97 ◽  
pp. 588-591 ◽  
Author(s):  
Jean Régis ◽  
Motohiro Hayashi ◽  
Denis Porcheron ◽  
Christine Delsanti ◽  
Xavier Muracciole ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Gamma Knife Radiosurgery ◽  
Positioning System ◽  
Major Advance ◽  
Content Type ◽  
Group I ◽  
The Mean ◽  
Model C ◽  
Automatic Positioning ◽  
Fine Print

Object. The technical advances associated with the model C gamma knife include a robotized system enabling automatic positioning of the stereotactic coordinates. The purpose of this study was to analyze the clinical impact of this technical modification. Methods. The authors studied a sample of patients with vestibular schwannoma (VS). This sample included three groups treated using gamma knife radiosurgery. Group I comprised 21 patients with VS treated just before the installation of the Automatic Positioning System (APS). Group II included patients in Group I with new dose plans created using the APS (in other words, simulated dose plans). Group III consisted of a control group of 20 patients matched for tumor grade with the previous group and treated recently with the APS. Treatment times were calculated after correcting the time for each shot according to the age of the sources after reloading. The treatment times, including total time, irradiation time, and duration of the neurosurgical procedure, were analyzed. In addition, dose planning including number of isocenters, number of different collimators, malfunctions, and the conformity and selectivity indices were recorded. The trend was to reduce the mean number of collimator runs from 7.9 to 1.2 and to increase the mean number of shots from 7.9 to 15.6, mostly by using the 4-mm collimator exclusively. The APS-related conformity and selectivity were improved from 95 to 97% and from 78 to 84%, respectively. The total treatment time was reduced by 53%, and time required to interact with the patient in the room was considerably reduced (75%), giving the neurosurgeon greater freedom to perform other tasks during the treatment period. The reduction of the time spent by the neurosurgeon at work in the room was 84%. The total radiation time was increased by 54%. Conclusions. The preliminary results of this study indicate that the robotization of the gamma knife is likely a major advance in radiosurgery.

First clinical experience with the automatic positioning system and Leksell gamma knife Model C

2000 ◽  
Vol 93 (supplement_3) ◽  
pp. 193-197 ◽  
Author(s):  
Gerhard A. Horstmann ◽  
Hans Schöpgens ◽  
Albertus T. C. J. van Eck ◽  
Hans-Jürg Kreiner ◽  
Wolfgang Herz
Keyword(s):  
Gamma Knife ◽  
Clinical Experience ◽  
Positioning System ◽  
Content Type ◽  
The Future ◽  
Narrow Space ◽  
Model C ◽  
Automatic Positioning ◽  
Fine Print

✓ In May of 1999, the first Leksell Model C gamma knife was installed at the Gamma Knife Zentrum in Krefeld, Germany. The authors recount their experience with this latest technical gamma knife development. Until the end of 1999, extensive physical and technical tests were performed and the system's hardware and software were continuously improved and adapted to the user's needs. By the end of 1999, 163 GKSs had been performed using the new functionality of the Model C in manual or “trunnion” mode. The trunnions, the two parts of the system that fix the patient headframe to the gamma knife when the isocenter positions, are checked manually. During the same period the new automatic positioning system (APS) was extensively tested and refined so that the first APS treatment could be performed in January 2000. Fifty GKSs have been performed with the APS capability of the Model C. It was possible to use APS alone in 74% of surgeries whereas in 14% some shots were given with APS and some with trunnions. In 12%, GKS was scheduled and planned for APS, but due to unexpected technical (6%) or mechanical (6%) reasons the treatment had to be performed manually. At present there are some spatial restrictions with Model C in APS mode when compared with the Model B. The most significant restriction is the narrow space for the patient's shoulders, especially when deep-seated lesions are treated. Through mechanical changes of the APS motor housing and some modifications of and to the motor driven couch adjustment, these limitations will be reduced in the future. The APS treatment runs smoothly and fast. In no case did any relevant safety error occur during GKS. The more stringent mechanical limitations of the APS compared with the Model B means that frame placement on the head is more critical than before.

Gamma knife radiosurgery for metastatic brain tumors from lung cancer: a comparison between small cell and non—small cell carcinoma

2002 ◽  
Vol 97 ◽  
pp. 484-488 ◽  
Author(s):  
Toru Serizawa ◽  
Junichi Ono ◽  
Toshihiko Iichi ◽  
Shinji Matsuda ◽  
Makoto Sato ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Brain Tumors ◽  
Gamma Knife ◽  
Gamma Knife Radiosurgery ◽  
Small Cell ◽  
Metastatic Brain Tumors ◽  
Cell Lung Carcinoma ◽  
Content Type ◽  
Significant Difference ◽  
Fine Print

Object. The purpose of this retrospective study was to evaluate the effectiveness of gamma knife radiosurgery (GKS) for the treatment of metastatic brain tumors from lung cancer, with particular reference to small cell lung carcinoma (SCLC) compared with non-SCLC (NSCLC). Methods. Two hundred forty-five consecutive patients meeting the following five criteria were evaluated in this study: 1) no prior brain tumor treatment; 2) 25 or fewer lesions; 3) a maximum of three tumors with a diameter of 20 mm or larger; 4) no surgically inaccessible tumor 30 mm or greater in diameter; and 5) more than 3 months of life expectancy. According to the same treatment protocol, large tumors (≥ 30 mm) were surgically removed and the other small lesions (< 30 mm) were treated with GKS. New lesions were treated with repeated GKS. Chemotherapy was administered, according to the primary physician's protocol, as aggressively as possible. Progression-free, overall, neurological, qualitative, and new lesion—free survival were calculated with the Kaplan—Meier method and were compared in the SCLC and NSCLC groups by using the log-rank test. The poor prognostic factors for each type of survival were also analyzed with the Cox proportional hazard model. Conclusions. Tumor control rate at 1 year was 94.5% in the SCLC group and 98% in the NSCLC group. The median survival time was 9.1 months in the SCLC group and 8.6 months in the NSCLC group. The 1-year survival rates in the SCLC group were 86.5% for neurological survival and 68.9% for qualitative survival; those in the NSCLC group were 87.9% for neurological and 78.9% for qualitative survival. The estimated median interval to emergence of a new lesion was 6.9 months in the SCLC group and 9.8 months in the NSCLC group. There was no significant difference between the two groups for any type of survival; this finding was verified by multivariate analysis. The results of this study suggest that GKS appears to be as effective in treating brain metastases from SCLC as for those from NSCLC.

Radiosurgery of vestibular schwannomas: summary of experience in 829 cases

2005 ◽  
Vol 102 ◽  
pp. 195-199 ◽  
Author(s):  
L. Dade Lunsford ◽  
Ajay Niranjan ◽  
John C. Flickinger ◽  
Ann Maitz ◽  
Douglas Kondziolka
Keyword(s):  
Quality Of Life ◽  
Gamma Knife ◽  
Cranial Nerve ◽  
Vestibular Schwannomas ◽  
Tumor Control ◽  
Content Type ◽  
Dose Planning ◽  
Fine Print

Object.Management options for vestibular schwannomas (VSs) have greatly expanded since the introduction of stereotactic radiosurgery. Optimal outcomes reflect long-term tumor control, preservation of cranial nerve function, and retention of quality of life. The authors review their 15-year experience.Methods.Between 1987 and 2002, some 829 patients with VSs underwent gamma knife surgery (GKS). Dose selection, imaging, and dose planning techniques evolved between 1987 and 1992 but thereafter remained stable for 10 years. The average tumor volume was 2.5 cm3. The median margin dose to the tumor was 13 Gy (range 10–20 Gy).No patient sustained significant perioperative morbidity. The average duration of hospital stay was less than 1 day. Unchanged hearing preservation was possible in 50 to 77% of patients (up to 90% in those with intracanalicular tumors). Facial neuropathy risks were reduced to less than 1%. Trigeminal symptoms were detected in less than 3% of patients whose tumors reached the level of the trigeminal nerve. Tumor control rates at 10 years were 97% (no additional treatment needed).Conclusions.Superior imaging, multiple isocenter volumetric conformal dose planning, and optimal precision and dose delivery contributed to the long-term success of GKS, including in those patients in whom initial microsurgery had failed. Gamma knife surgery provides a low risk, minimally invasive treatment option for patients with newly diagnosed or residual VS. Cranial nerve preservation and quality of life maintenance are possible in long-term follow up.

Impact on the quality of life of patients with arteriovenous malformations during the latent interval between gamma knife radiosurgery and lesion obliteration

2002 ◽  
Vol 97 ◽  
pp. 471-473 ◽  
Author(s):  
Erica Ho Pik Lai ◽  
Samuel Leung Cheong Lun
Keyword(s):  
Quality Of Life ◽  
Gamma Knife ◽  
Arteriovenous Malformations ◽  
Gamma Knife Radiosurgery ◽  
Medical Problems ◽  
Waiting Period ◽  
Content Type ◽  
Latent Interval ◽  
Fine Print

Object. The aim of this study was to measure the quality of life (QOL) in patients with cerebral arteriovenous malformations (AVMs) receiving gamma knife treatment before total AVM obliteration. Quality of life was assessed as it related to the knowledge of rebleeding risk during the waiting period, AVM symptoms, and previous bleeding. Methods. Thirty-nine patients age 18 years or older without other medical problems were asked to complete a questionnaire that included demographic variables, immediate effect of gamma knife radiosurgery, symptoms of AVM, previous hemorrhage, and the Duke—University of North Carolina Health Profile (63 items). Conclusions. The QOL of patients with cerebral AVM during the waiting period after undergoing gamma knife treatment was affected by irreversible physical disabilities rather than the knowledge of hemorrhage risk and bleeding experience.

Radiation exposure of normal temporal bone structures during stereotactically guided gamma knife surgery for vestibular schwannomas

2003 ◽  
Vol 98 (4) ◽  
pp. 800-806 ◽  
Author(s):  
Mark E. Linskey ◽  
Peter A. S. Johnstone ◽  
Michael O'Leary ◽  
Steven Goetsch
Keyword(s):  
Hearing Loss ◽  
Radiation Exposure ◽  
Gamma Knife ◽  
External Ear ◽  
Content Type ◽  
Tumor Margin ◽  
Tolerance Dose ◽  
High Doses ◽  
Bone Structures ◽  
Fine Print

Object. The dosimetry of radiation exposure of healthy inner, middle, and external ear structures that leads to hearing loss, tinnitus, facial weakness, dizziness, vertigo, and imbalance after gamma knife surgery (GKS) for vestibular schwannomas (VSs) is unknown. The authors quantified the dose of radiation received by these structures after GKS for VS to assess the likelihood that these doses contributed to postradiosurgery complications. Methods. A retrospective study was performed using a prospectively acquired database of a consecutive series of 54 patients with VS who were treated with GKS during a 3.5-year period at an “open unit” gamma knife center. Point doses were measured for 18 healthy temporal bone structures in each patient, with the anatomical position of each sampling point confirmed by a fellowship-trained neurootologist. These values were compared against single-dose equivalents for the 5-year tolerance dose for a 5% risk of complications and the 5-year tolerance dose for a 50% risk of complications, which were calculated using known 2-Gy/fraction thresholds for chronic otitis, chondromalacia, and osseous necrosis, as well as the tumor margin dose and typical tumor margin prescription doses for patients in whom hearing preservation was attempted. External and middle ear doses were uniformly low. The intratemporal facial nerve is susceptible to unintentionally high radiation exposure at the fundus of the internal auditory canal, with higher than tumor margin doses detected in 26% of cases. In the cochlea, the basal turn near the modiolus and its inferior portion are most susceptible, with doses greater than 12 Gy detected in 10.8 and 14.8% of cases. In the vestibular labyrinth, the ampulated ends of the lateral and posterior semicircular canals are most susceptible, with doses greater than 12 Gy detected in 7.4 and 5.1% of cases. Conclusions. Doses delivered to middle and external ear structures are unlikely to contribute to post-GKS complications, but unexpectedly high doses may be delivered to sensitive areas of the intratemporal facial nerve and inner ear. Unintentional delivery of high doses to the stria vascularis, the sensory neuroepithelium of the inner ear organs and/or their ganglia, may play a role in the development of post-GKS tinnitus, hearing loss, dizziness, vertigo, and imbalance. Minimizing treatment complications post-GKS for VS requires precise dose planning conformality with the three-dimensional surface of the tumor.

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