Gamma knife radiosurgery for cerebellopontine angle epidermoid tumors.

Science.gov (United States)

El-Shehaby, Amr M N; Reda, Wael A; Abdel Karim, Khaled M; Emad Eldin, Reem M; Nabeel, Ahmed M

2017-01-01

Intracranial epidermoid tumors are commonly found in the cerebellopontine angle where they usually present with either trigeminal neuralgia or hemifacial spasm. Radiosurgery for these tumors has rarely been reported. The purpose of this study is to assess the safety and clinical outcome of the treatment of cerebellopontine epidermoid tumors with gamma knife radiosurgery. This is a retrospective study involving 12 patients harboring cerebellopontine angle epidermoid tumors who underwent 15 sessions of gamma knife radiosurgery. Trigeminal pain was present in 8 patients and hemifacial spasm in 3 patients. All cases with trigeminal pain were receiving medication and still uncontrolled. One patient with hemifacial spasm was medically controlled before gamma knife and the other two were not. Two patients had undergone surgical resection prior to gamma knife treatment. The median prescription dose was 11 Gy (10-11 Gy). The tumor volumes ranged from 3.7 to 23.9 cc (median 10.5 cc). The median radiological follow up was 2 years (1-5 years). All tumors were controlled and one tumor shrank. The median clinical follow-up was 5 years. The trigeminal pain improved or disappeared in 5 patients, and of these, 4 cases stopped their medication and one decreased it. The hemifacial spasm resolved in 2 patients who were able to stop their medication. Facial palsy developed in 1 patient and improved with conservative treatment. Transient diplopia was also reported in 2 cases. Gamma knife radiosurgery provides good clinical control for cerebellopontine angle epidermoid tumors.

Long-Term Results of Gamma Knife Radiosurgery for Intracranial Meningioma.

Science.gov (United States)

Jang, Chang Ki; Jung, Hyun Ho; Chang, Jong Hee; Chang, Jin Woo; Park, Yong Gou; Chang, Won Seok

2015-10-01

The predominant treatment modality for meningioma is surgical resection. However, gamma knife radiosurgery is also an important treatment modality for meningioma that is small or cannot be completely removed because of its location. In this study, we evaluated the effectiveness and long-term results of radiosurgical treatment for meningioma in our institution. We studied 628 patients (130 men and 498 women) who underwent gamma knife radiosurgery for intracranial meningioma, which is radiologically diagnosed, from Jan 2008 to Nov 2012. We included patients with single lesion meningioma, and followed up after 6 months with imaging, and then at 24 months with a clinical examination. Patients with high-grade meningioma or multiple meningiomas were excluded. We analyzed each of the factors associated with progression free survival. The median patient's age was 56.8 years. Maximal dosage was 27.8 Gy and marginal dosage was 13.9 Gy. The overall tumor control rate was 95%. Twenty-eight patients (4.4%) showed evidence of tumor recurrence. Ninety-eight patients (15%) developed peritumoral edema (PTE) after gamma-knife surgery; two of them (2%) underwent surgical resections due to PTE. Nine patients had craniotomy and tumor removal after gamma knife surgery. Gamma knife surgery for intracranial meningioma has proven to be a safe and effective treatment tool with successful long-term outcomes. Gamma knife radiosurgery can be especially effective in cases of remnant meningioma after surgical resection or where PTE is not present.

Forward treatment planning techniques to reduce the normalization effect in Gamma Knife radiosurgery.

Science.gov (United States)

Cheng, Hao-Wen; Lo, Wei-Lun; Kuo, Chun-Yuan; Su, Yu-Kai; Tsai, Jo-Ting; Lin, Jia-Wei; Wang, Yu-Jen; Pan, David Hung-Chi

2017-11-01

In Gamma Knife forward treatment planning, normalization effect may be observed when multiple shots are used for treating large lesions. This effect can reduce the proportion of coverage of high-value isodose lines within targets. The aim of this study was to evaluate the performance of forward treatment planning techniques using the Leksell Gamma Knife for the normalization effect reduction. We adjusted the shot positions and weightings to optimize the dose distribution and reduce the overlap of high-value isodose lines from each shot, thereby mitigating the normalization effect during treatment planning. The new collimation system, Leksell Gamma Knife Perfexion, which contains eight movable sectors, provides an additional means to reduce the normalization effect by using composite shots. We propose different techniques in forward treatment planning that can reduce the normalization effect. Reducing the normalization effect increases the coverage proportion of higher isodose lines within targets, making the high-dose region within targets more uniform and increasing the mean dose to targets. Because of the increase in the mean dose to the target after reducing the normalization effect, we can set the prescribed marginal dose at a higher isodose level and reduce the maximum dose, thereby lowering the risk of complications. © 2017 Shuang Ho Hospital-Taipei Medical University. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Gamma knife surgery for craniopharyngioma

International Nuclear Information System (INIS)

Prasad, D.; Steiner, M.; Steiner, L.

1995-01-01

We present our results of Gamma Knife surgery for craniopharyngioma in nine patients. The current status of surgery, radiation therapy, intracavitary instillation of radionuclides and Gamma Knife surgery in the management of craniopharyngiomas is discussed. (author)

Gamma-Knife: operation ohne Skalpell

OpenAIRE

АБЛЯЕВА В.И.; НИКОЛАЕВА Н.А.; ДЕНИСОВА О.С.

2015-01-01

Das Gamma-Knife ist ein Operationsroboter, mit dem Ärzte durch Photonenstrahlen im Körper operieren können. Die Photonen beschädigen die DNA von Zellen, so dass diese sich nicht mehr teilen können. Gutartige Tumoren vernarben in den Wochen und Monaten nach der Behandlung, bösartige zerfallen. Mit dem Gamma-Knife können unterschiedliche Arten von Tumoren behandelt werden, gutartige ebenso wie bösartige. Zu den Diagnosen, bei denen das Gamma-Knife in Frage kommt, gehören zum Beispiel Akustikusn...

Plan Quality and Treatment Efficiency for Radiosurgery to Multiple Brain Metastases: Non-Coplanar RapidArc vs Gamma Knife

Directory of Open Access Journals (Sweden)

Haisong eLiu

2016-02-01

Full Text Available Objectives: This study compares the dosimetry and efficiency of two modern radiosurgery (SRS modalities for multiple brain metastases (Gamma Knife and LINAC-based RapidArc/volumetric modulated arc therapy, with a special focus on the comparison of low dose spread.Methods: Six patients with three or four small brain metastases were used in this study. The size of targets varied from 0.1 ~ 10.5 cc. SRS doses were prescribed according to size of lesions. SRS plans were made using both Gamma Knife® Perfexion and a single-isocenter, multiple non-coplanar RapidArc®. Dosimetric parameters analyzed included RTOG conformity index (CI, gradient index (GI, 12 Gy isodose volume (V12Gy for each target, and the dose spread (Dspread for each plan. Dspread reflects SRS plan’s capability of confining radiation to within the local vicinity of the lesion and to not spread out to the surrounding normal brain tissues. Each plan has a dose (Dspread, such that once dose decreases below Dspread (on total tissue DVH, isodose volume starts increasing dramatically. Dspread is defined as that dose when volume increase first exceeds 20 cc per 0.1 Gy dose decrease. Results: RapidArc SRS has smaller CI (1.19 ±0.14 vs. 1.50 ± 0.16, p<0.001 and larger GI (4.77 ± 1.49 vs. 3.65 ± 0.98, p <0.01. V12Gy results were comparable (2.73 ± 1.38 cc vs. 3.06 ± 2.20 cc, p = 0.58. Moderate to lower dose spread, V6, V4.5, and V3, were also equivalent. Gamma Knife plans achieved better very low dose spread (≤3 Gy and also had slightly smaller Dspread, 1.9 Gy vs 2.5 Gy. Total treatment time for Gamma Knife is estimated between 60~100 min. Gamma Knife treatments are between 3~5 times longer compared to RapidArc treatment techniques.Conclusion: Dosimetric parameters reflecting prescription dose conformality (CI, dose fall off (GI, radiation necrosis indicator (V12Gy, and dose spread (Dspread were compared between Gamma Knife SRS and RapidArc SRS for multi-mets. RapidArc plans have

Failure modes and effects analysis (FMEA) for Gamma Knife radiosurgery.

Science.gov (United States)

Xu, Andy Yuanguang; Bhatnagar, Jagdish; Bednarz, Greg; Flickinger, John; Arai, Yoshio; Vacsulka, Jonet; Feng, Wenzheng; Monaco, Edward; Niranjan, Ajay; Lunsford, L Dade; Huq, M Saiful

2017-11-01

Gamma Knife radiosurgery is a highly precise and accurate treatment technique for treating brain diseases with low risk of serious error that nevertheless could potentially be reduced. We applied the AAPM Task Group 100 recommended failure modes and effects analysis (FMEA) tool to develop a risk-based quality management program for Gamma Knife radiosurgery. A team consisting of medical physicists, radiation oncologists, neurosurgeons, radiation safety officers, nurses, operating room technologists, and schedulers at our institution and an external physicist expert on Gamma Knife was formed for the FMEA study. A process tree and a failure mode table were created for the Gamma Knife radiosurgery procedures using the Leksell Gamma Knife Perfexion and 4C units. Three scores for the probability of occurrence (O), the severity (S), and the probability of no detection for failure mode (D) were assigned to each failure mode by 8 professionals on a scale from 1 to 10. An overall risk priority number (RPN) for each failure mode was then calculated from the averaged O, S, and D scores. The coefficient of variation for each O, S, or D score was also calculated. The failure modes identified were prioritized in terms of both the RPN scores and the severity scores. The established process tree for Gamma Knife radiosurgery consists of 10 subprocesses and 53 steps, including a subprocess for frame placement and 11 steps that are directly related to the frame-based nature of the Gamma Knife radiosurgery. Out of the 86 failure modes identified, 40 Gamma Knife specific failure modes were caused by the potential for inappropriate use of the radiosurgery head frame, the imaging fiducial boxes, the Gamma Knife helmets and plugs, the skull definition tools as well as other features of the GammaPlan treatment planning system. The other 46 failure modes are associated with the registration, imaging, image transfer, contouring processes that are common for all external beam radiation therapy

SU-F-SPS-10: The Dosimetric Comparison of GammaKnife and Cyberknife Treatment Plans for Brain SRS Treatment

International Nuclear Information System (INIS)

Sanli, E; Mabhouti, H; Cebe, M; Codel, G; Pacaci, P; Serin, E; Kucuk, N; Kucukmorkoc, E; Doyuran, M; Canoglu, D; Altinok, A; Acar, H; Caglar Ozkok, H

2016-01-01

Purpose: Brain stereotactic radiosurgery (SRS) involves the use of precisely directed, single session radiation to create a desired radiobiologic response within the brain target with acceptable minimal effects on surrounding structures or tissues. In this study, the dosimetric comparison of GammaKnife perfection and Cyberknife M6 treatment plans were made. Methods: Treatment plannings were done for GammaKnife perfection unit using Gammaplan treatment planning system (TPS) on the CT scan of head and neck randophantom simulating the treatment of sterotactic treatments for one brain metastasis. The dose distribution were calculated using TMR 10 algorithm. The treatment planning for the same target were also done for Cyberknife M6 machine using Multiplan (TPS) with Monte Carlo algorithm. Using the same film batch, the net OD to dose calibration curve was obtained using both machine by delivering 0- 800 cGy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. Dose distribution were measured using EBT3 film dosimeter. The measured and calculated doses were compared. Results: The dose distribution in the target and 2 cm beyond the target edge were calculated on TPSs and measured using EBT3 film. For cyberknife treatment plans, the gamma analysis passing rates between measured and calculated dose distributions were 99.2% and 96.7% for target and peripheral region of target respectively. For gammaknife treatment plans, the gamma analysis passing rates were 98.9% and 93.2% for target and peripheral region of target respectively. Conclusion: The study shows that dosimetrically comparable plans are achievable with Cyberknife and GammaKnife. Although TMR 10 algorithm predicts the target dose

SU-F-SPS-10: The Dosimetric Comparison of GammaKnife and Cyberknife Treatment Plans for Brain SRS Treatment

Energy Technology Data Exchange (ETDEWEB)

Sanli, E; Mabhouti, H; Cebe, M; Codel, G; Pacaci, P; Serin, E; Kucuk, N; Kucukmorkoc, E; Doyuran, M; Canoglu, D; Altinok, A; Acar, H; Caglar Ozkok, H [Medipol University, Istanbul, Istanbul (Turkey)

2016-06-15

Purpose: Brain stereotactic radiosurgery (SRS) involves the use of precisely directed, single session radiation to create a desired radiobiologic response within the brain target with acceptable minimal effects on surrounding structures or tissues. In this study, the dosimetric comparison of GammaKnife perfection and Cyberknife M6 treatment plans were made. Methods: Treatment plannings were done for GammaKnife perfection unit using Gammaplan treatment planning system (TPS) on the CT scan of head and neck randophantom simulating the treatment of sterotactic treatments for one brain metastasis. The dose distribution were calculated using TMR 10 algorithm. The treatment planning for the same target were also done for Cyberknife M6 machine using Multiplan (TPS) with Monte Carlo algorithm. Using the same film batch, the net OD to dose calibration curve was obtained using both machine by delivering 0- 800 cGy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. Dose distribution were measured using EBT3 film dosimeter. The measured and calculated doses were compared. Results: The dose distribution in the target and 2 cm beyond the target edge were calculated on TPSs and measured using EBT3 film. For cyberknife treatment plans, the gamma analysis passing rates between measured and calculated dose distributions were 99.2% and 96.7% for target and peripheral region of target respectively. For gammaknife treatment plans, the gamma analysis passing rates were 98.9% and 93.2% for target and peripheral region of target respectively. Conclusion: The study shows that dosimetrically comparable plans are achievable with Cyberknife and GammaKnife. Although TMR 10 algorithm predicts the target dose.

Concomitant GRID boost for Gamma Knife radiosurgery

International Nuclear Information System (INIS)

Ma Lijun; Kwok, Young; Chin, Lawrence S.; Simard, J. Marc; Regine, William F.

2005-01-01

We developed an integrated GRID boost technique for Gamma Knife radiosurgery. The technique generates an array of high dose spots within the target volume via a grid of 4-mm shots. These high dose areas were placed over a conventional Gamma Knife plan where a peripheral dose covers the full target volume. The beam weights of the 4-mm shots were optimized iteratively to maximize the integral dose inside the target volume. To investigate the target volume coverage and the dose to the adjacent normal brain tissue for the technique, we compared the GRID boosted treatment plans with conventional Gamma Knife treatment plans using physical and biological indices such as dose-volume histogram (DVH), DVH-derived indices, equivalent uniform dose (EUD), tumor control probabilities (TCP), and normal tissue complication probabilities (NTCP). We found significant increase in the target volume indices such as mean dose (5%-34%; average 14%), TCP (4%-45%; average 21%), and EUD (2%-22%; average 11%) for the GRID boost technique. No significant change in the peripheral dose coverage for the target volume was found per RTOG protocol. In addition, the EUD and the NTCP for the normal brain adjacent to the target (i.e., the near region) were decreased for the GRID boost technique. In conclusion, we demonstrated a new technique for Gamma Knife radiosurgery that can escalate the dose to the target while sparing the adjacent normal brain tissue

Role of gamma knife radiosurgery in neurosurgery. Past and future perspectives

International Nuclear Information System (INIS)

Koga, Tomoyuki; Shin, Masahiro; Saito, Nobuhito

2010-01-01

The gamma knife was the first radiosurgical device developed at the Karolinska Institute in 1967. Stereotactic radiosurgery using the gamma knife has been widely accepted in clinical practice and has contributed to the development of neurosurgery. More than 500,000 patients have been treated by gamma knife stereotactic radiosurgery so far, and the method is now an indispensable neurosurgical tool. Here we review long-term outcomes and development of stereotactic radiosurgery using the gamma knife and discuss its future perspectives. The primary role of stereotactic radiosurgery is to control small well-demarcated lesions such as metastatic brain tumors, meningiomas, schwannomas, and pituitary adenomas while preserving the function of surrounding brain tissue. The gamma knife has been used as a primary treatment or in combination with surgery, and some applications have been accepted as standard treatment in the field of neurosurgery. Treatment of cerebral arteriovenous malformations has also been drastically changed after emergence of this technology. Controlling functional disorders is another role of stereotactic radiosurgery. There is a risk of radiation-induced adverse events, which are usually mild and less frequent. However, especially in large or invasive lesions, those risks are not negligible and pose limitations. Advancement of irradiation technology and dose planning software have enabled more sophisticated and safer treatment, and further progress will contribute to better treatment outcomes not only for brain lesions but also for cervical lesions with less invasive treatment. (author)

Study of apoptosis and Caspase-3, Fas expression in rat glioma after treatment with gamma knife

International Nuclear Information System (INIS)

Zhao Qingqiu; Zhao Wenqing; Yue Xiangyong; Du Yali; Dong Liying; Zhou Lixia

2003-01-01

Objective: To investigate the apoptosis and Caspase-3, Fas expression in rat glioma after treatment with gamma knife. Methods: Setting up C6 glioma model with 60 rats, which were divided into a treatment group ( n= 30) and a control group (n=30). On the 14 th day after planting glioma cells, rats of the treatment group were subjected to gamma knife irradiation. At the 12 th hr, 24 th hr, 48 th hr, 7 th day, 14 th day, 21 st day, flow cytometry was performed to estimate the glioma cells' apoptosis and the expression of Caspase-3 and Fas. The relation between apoptosis and the two kinds of proteins was analysed. Results: Compared with the control group, the apoptosis rate of the glioma cells in the treatment group increased obviously (P th hr reached its peak, then decreased gradually. The expression of Caspase-3 and Fas was positively correlated with apoptosis (r 1 =0.928, r 2 =0.916). Conclusion: The apoptosis of the tumor cells is a kind of effect of gamma knife treatment. Caspase-3 and Fas gene may take part in the regulation of apoptosis

Plug pattern optimization for gamma knife radiosurgery treatment planning

International Nuclear Information System (INIS)

Zhang Pengpeng; Wu, Jackie; Dean, David; Xing Lei; Xue Jinyue; Maciunas, Robert; Sibata, Claudio

2003-01-01

Purpose: To develop a novel dose optimization algorithm for improving the sparing of critical structures during gamma knife radiosurgery by shaping the plug pattern of each individual shot. Method and Materials: We first use a geometric information (medial axis) aided guided evolutionary simulated annealing (GESA) optimization algorithm to determine the number of shots and isocenter location, size, and weight of each shot. Then we create a plug quality score system that checks the dose contribution to the volume of interest by each plug in the treatment plan. A positive score implies that the corresponding source could be open to improve tumor coverage, whereas a negative score means the source could be blocked for the purpose of sparing normal and critical structures. The plug pattern is then optimized via the GESA algorithm that is integrated with this score system. Weight and position of each shot are also tuned in this procedure. Results: An acoustic tumor case is used to evaluate our algorithm. Compared to the treatment plan generated without plug patterns, adding an optimized plug pattern into the treatment planning process boosts tumor coverage index from 95.1% to 97.2%, reduces RTOG conformity index from 1.279 to 1.167, lowers Paddick's index from 1.34 to 1.20, and trims the critical structure receiving more than 30% maximum dose from 16 mm 3 to 6 mm 3 . Conclusions: Automated GESA-based plug pattern optimization of gamma knife radiosurgery frees the treatment planning team from the manual forward planning procedure and provides an optimal treatment plan

Verification of Gamma Knife extend system based fractionated treatment planning using EBT2 film

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Natanasabapathi, Gopishankar; Bisht, Raj Kishor [Gamma Knife Unit, Department of Neurosurgery, Neurosciences Centre, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029 (India)

2013-12-15

Purpose: This paper presents EBT2 film verification of fractionated treatment planning with the Gamma Knife (GK) extend system, a relocatable frame system for multiple-fraction or serial multiple-session radiosurgery.Methods: A human head shaped phantom simulated the verification process for fractionated Gamma Knife treatment. Phantom preparation for Extend Frame based treatment planning involved creating a dental impression, fitting the phantom to the frame system, and acquiring a stereotactic computed tomography (CT) scan. A CT scan (Siemens, Emotion 6) of the phantom was obtained with following parameters: Tube voltage—110 kV, tube current—280 mA, pixel size—0.5 × 0.5 and 1 mm slice thickness. A treatment plan with two 8 mm collimator shots and three sectors blocking in each shot was made. Dose prescription of 4 Gy at 100% was delivered for the first fraction out of the two fractions planned. Gafchromic EBT2 film (ISP Wayne, NJ) was used as 2D verification dosimeter in this process. Films were cut and placed inside the film insert of the phantom for treatment dose delivery. Meanwhile a set of films from the same batch were exposed from 0 to 12 Gy doses for calibration purposes. An EPSON (Expression 10000 XL) scanner was used for scanning the exposed films in transparency mode. Scanned films were analyzed with inhouse written MATLAB codes.Results: Gamma index analysis of film measurement in comparison with TPS calculated dose resulted in high pass rates >90% for tolerance criteria of 1%/1 mm. The isodose overlay and linear dose profiles of film measured and computed dose distribution on sagittal and coronal plane were in close agreement.Conclusions: Through this study, the authors propose treatment verification QA method for Extend frame based fractionated Gamma Knife radiosurgery using EBT2 film.

Verification of Gamma Knife extend system based fractionated treatment planning using EBT2 film

International Nuclear Information System (INIS)

Natanasabapathi, Gopishankar; Bisht, Raj Kishor

2013-01-01

Purpose: This paper presents EBT2 film verification of fractionated treatment planning with the Gamma Knife (GK) extend system, a relocatable frame system for multiple-fraction or serial multiple-session radiosurgery.Methods: A human head shaped phantom simulated the verification process for fractionated Gamma Knife treatment. Phantom preparation for Extend Frame based treatment planning involved creating a dental impression, fitting the phantom to the frame system, and acquiring a stereotactic computed tomography (CT) scan. A CT scan (Siemens, Emotion 6) of the phantom was obtained with following parameters: Tube voltage—110 kV, tube current—280 mA, pixel size—0.5 × 0.5 and 1 mm slice thickness. A treatment plan with two 8 mm collimator shots and three sectors blocking in each shot was made. Dose prescription of 4 Gy at 100% was delivered for the first fraction out of the two fractions planned. Gafchromic EBT2 film (ISP Wayne, NJ) was used as 2D verification dosimeter in this process. Films were cut and placed inside the film insert of the phantom for treatment dose delivery. Meanwhile a set of films from the same batch were exposed from 0 to 12 Gy doses for calibration purposes. An EPSON (Expression 10000 XL) scanner was used for scanning the exposed films in transparency mode. Scanned films were analyzed with inhouse written MATLAB codes.Results: Gamma index analysis of film measurement in comparison with TPS calculated dose resulted in high pass rates >90% for tolerance criteria of 1%/1 mm. The isodose overlay and linear dose profiles of film measured and computed dose distribution on sagittal and coronal plane were in close agreement.Conclusions: Through this study, the authors propose treatment verification QA method for Extend frame based fractionated Gamma Knife radiosurgery using EBT2 film

The costs of radiosurgical treatment: Comparison between gamma knife and linear accelerator

International Nuclear Information System (INIS)

Koenigsmaier, H.; Pauli-Ferch, B. de; Hackl, A.; Pendl, G.

1998-01-01

Radiosurgical treatment can be carried out by means of a gamma knife or a linear accelerator. The linear accelerator may be either a single-purpose appliance, exclusively employed in radiosurgery, or an adapted appliance which is used primarily for fractioned radiotherapy, and only additionally for radiosurgical purposes. The first alternative will be referred to briefly as a 'dedicated Linac', the latter as an 'adapted Linac'. Cost accounting data for these alternatives will be discussed under three main categories: investment costs. operating costs, and finally staffing costs. Costs are only considered to the extent that this is necessary to facilitate a comprehensive cost comparison. Factors for which the costs remain the same or at least broadly the same will from the outset not be taken into consideration. These include, for instance, the costs of general or special administration, diagnosis, and image processing. The results and conclusions of this study therefore cannot be employed immediately in the evaluation of cost reimbursement schemes of the type carried out by agencies responsible for social insurance. Here, appropriate complete cost analyzes especially for this purpose are required. The final comprehensive cost comparison reveals that the adapted Linac is the most favourable alternative with small annual quantities of patients. With larger numbers of patients the Gamma Knife represents the most favourable from a cost accounting angle. The dedicated Linac accordingly does not have a cost advantage for any of the examined numbers of patients. Clearly the lowest treatment costs per patient can be achieved by employing a Gamma Knife and using it to capacity. (author)

Gamma knife radiosurgery in movement disorders: Indications and limitations.

Science.gov (United States)

Higuchi, Yoshinori; Matsuda, Shinji; Serizawa, Toru

2017-01-01

Functional radiosurgery has advanced steadily during the past half century since the development of the gamma knife technique for treating intractable cancer pain. Applications of radiosurgery for intracranial diseases have increased with a focus on understanding radiobiology. Currently, the use of gamma knife radiosurgery to ablate deep brain structures is not widespread because visualization of the functional targets remains difficult despite the increased availability of advanced neuroimaging technology. Moreover, most existing reports have a small sample size or are retrospective. However, increased experience with intraoperative neurophysiological evaluations in radiofrequency thalamotomy and deep brain stimulation supports anatomical and neurophysiological approaches to the ventralis intermedius nucleus. Two recent prospective studies have promoted the clinical application of functional radiosurgery for movement disorders. For example, unilateral gamma knife thalamotomy is a potential alternative to radiofrequency thalamotomy and deep brain stimulation techniques for intractable tremor patients with contraindications for surgery. Despite the promising efficacy of gamma knife thalamotomy, however, these studies did not include sufficient follow-up to confirm long-term effects. Herein, we review the radiobiology literature, various techniques, and the treatment efficacy of gamma knife radiosurgery for patients with movement disorders. Future research should focus on randomized controlled studies and long-term effects. © 2016 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.

Radiosurgery with the gamma knife; Radiochirurgie mit dem Gamma-Knife

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Wowra, B.; Reulen, H.J.

1996-05-10

Radiosurgery is a novel modality introduced by the neurosurgeon Lars Leksell. For the most important lesions, (arteriovenous angiomas, benign tumors in the base of the skull, formation of metastases in the brain), radiosurgery is a valuable additional tool in the range of therapies available to the benefit of patients. The gamma knife has been gaining a leading rank in the range of therapies applied in Germany. (orig.) [Deutsch] Radiochirurgie ist ein neues, von dem Neurochirurgen Lars Leksell konzipiertes Prinzip. Bei den wichtigsten Indikationen (arteriovenoese Angiome, gutartige Tumoren der Schaedelbasis, Hirnmetastasen etc.) bereichert und ergaenzt die Radiochirurgie das therapeutische Arsenal der Neurochirurgie zum Vorteil der Patienten betraechtlich. Dem Gamma-Knife kommt jetzt auch in Deutschland ein prominenter Platz unter den verschiedenen radiochirurgischen Verfahren zu. (orig.)

The current role of Gamma Knife radiosurgery in the management of intracranial haemangiopericytoma.

Science.gov (United States)

Spina, Alfio; Boari, Nicola; Gagliardi, Filippo; Donofrio, Carmine A; Franzin, Alberto; Mortini, Pietro

2016-04-01

Haemangiopericytomas (HPCs) are rare tumours characterised by aggressive behaviour with tendency to local recurrence and to metastasise. WHO grade II and grade III tumours show different progression-free survival and overall survival rates. Gross total tumour resection is still considered the treatment of choice. Adjuvant radiation therapies represent an option in the treatment strategy regardless the extent of resection. Based on this consideration, Gamma Knife radiosurgery has been introduced either as a primary treatment or as an adjuvant treatment for residual or recurrent tumours. A systematic search was performed on PubMed, Web of Science and Google Scholar for clinical series reporting Gamma Knife radiosurgery, Cyberknife and Linear Accelerator (LINAC) for the management of intracranial HPCs. Fourteen studies focusing on the effects of Gamma Knife radiosurgery for intracranial HPCs were included. Four studies reported data on Cyberknife radiosurgery and LINAC. A total of 208 patients harbouring 366 tumours have been reported. Patient's features, radiosurgical treatment characteristics and follow-up data of the pertinent literature have been critically revised. Gamma Knife radiosurgery and the other radiosurgical techniques represent a feasible and effective therapy in the management of HPCs. Tumour control and survival rate are comparable to those reported for radiotherapy. Further studies should be focused to define the exact role of Gamma Knife radiosurgery in the management of HPCs.

Gamma Knife Treatment of Brainstem Metastases

Science.gov (United States)

Peterson, Halloran E.; Larson, Erik W.; Fairbanks, Robert K.; MacKay, Alexander R.; Lamoreaux, Wayne T.; Call, Jason A.; Carlson, Jonathan D.; Ling, Benjamin C.; Demakas, John J.; Cooke, Barton S.; Peressini, Ben; Lee, Christopher M.

2014-01-01

The management of brainstem metastases is challenging. Surgical treatment is usually not an option, and chemotherapy is of limited utility. Stereotactic radiosurgery has emerged as a promising palliative treatment modality in these cases. The goal of this study is to assess our single institution experience treating brainstem metastases with Gamma Knife radiosurgery (GKRS). This retrospective chart review studied 41 patients with brainstem metastases treated with GKRS. The most common primary tumors were lung, breast, renal cell carcinoma, and melanoma. Median age at initial treatment was 59 years. Nineteen (46%) of the patients received whole brain radiation therapy (WBRT) prior to or concurrent with GKRS treatment. Thirty (73%) of the patients had a single brainstem metastasis. The average GKRS dose was 17 Gy. Post-GKRS overall survival at six months was 42%, at 12 months was 22%, and at 24 months was 13%. Local tumor control was achieved in 91% of patients, and there was one patient who had a fatal brain hemorrhage after treatment. Karnofsky performance score (KPS) >80 and the absence of prior WBRT were predictors for improved survival on multivariate analysis (HR 0.60 (p = 0.02), and HR 0.28 (p = 0.02), respectively). GKRS was an effective treatment for brainstem metastases, with excellent local tumor control. PMID:24886816

The use of a Leksell-BRW adapter for linac radiosurgery as an adjunct to Gamma Knife treatment

International Nuclear Information System (INIS)

Ekstrand, Kenneth E; Hinson, William H; Bourland, J Daniel; Guzman, Allan F de; Stieber, Volker W; Tatter, Steven B; Ellis, Thomas L

2003-01-01

We have investigated the use of an adapter that permits the use of a Leksell coordinate frame with a linear accelerator stereotactic radiosurgery system based on the Brown-Robert-Wells (BRW) design. This device is useful when lesions that are planned for treatment on a Leksell Gamma Knife system are found to be inaccessible to the Gamma Knife. We have found that with this device objects within a head phantom can be targeted by the linear accelerator within an accuracy of approximately 1 mm

The use of a Leksell-BRW adapter for linac radiosurgery as an adjunct to Gamma Knife treatment

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Ekstrand, Kenneth E [Department of Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Hinson, William H [Department of Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Bourland, J Daniel [Department of Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Guzman, Allan F de [Department of Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Stieber, Volker W [Department of Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Tatter, Steven B [Department of Neurosurgery, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Ellis, Thomas L [Department of Neurosurgery, Wake Forest University School of Medicine, Winston-Salem, NC (United States)

2003-12-21

We have investigated the use of an adapter that permits the use of a Leksell coordinate frame with a linear accelerator stereotactic radiosurgery system based on the Brown-Robert-Wells (BRW) design. This device is useful when lesions that are planned for treatment on a Leksell Gamma Knife system are found to be inaccessible to the Gamma Knife. We have found that with this device objects within a head phantom can be targeted by the linear accelerator within an accuracy of approximately 1 mm.

Stereotactic radiosurgery using the gamma knife

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Kawamoto, Shunsuke; Sasaki, Tomio; Matsutani, Masao; Takakura, Kintomo; Terahara, Atsuro (Tokyo Univ. (Japan). Faculty of Medicine)

1992-03-01

Since stereotactic radiosurgery using a gamma knife was developed in 1968 by Leksell, it has been used with increasing frequency in Japan. During the period from June 19, 1990 through December 20, 1991, 218 patients have been treated with stereotactic radiosurgery using a gamma knife. Of them, 116 had vascular lesions (116), including arteriovenous malformation (114), dural arteriovenous malformation (one), and cerebral aneurysm (one); and the other 102 had tumorous lesions, including acoustic neurinoma (48), meningioma (26), pituitary tumor (11), metastatic tumor (7), germ cell tumor (3), glioma (2), hemangioblastoma (2), chordoma (one), craniopharyngioma (one), and trigeminal neurinoma (one). In this article, candidates of stereotactic radiosurgery using a gamma knife are discussed, with particular attention to clinical results of the aforementioned 218 patients. (N.K.) 54 refs.

A microcosting study of microsurgery, LINAC radiosurgery, and gamma knife radiosurgery in meningioma patients

Science.gov (United States)

van Putten, Erik; Nijdam, Wideke M.; Hanssens, Patrick; Beute, Guus N.; Nowak, Peter J.; Dirven, Clemens M.; Hakkaart-van Roijen, Leona

2010-01-01

The aim of the present study is to determine and compare initial treatment costs of microsurgery, linear accelerator (LINAC) radiosurgery, and gamma knife radiosurgery in meningioma patients. Additionally, the follow-up costs in the first year after initial treatment were assessed. Cost analyses were performed at two neurosurgical departments in The Netherlands from the healthcare providers’ perspective. A total of 59 patients were included, of whom 18 underwent microsurgery, 15 underwent LINAC radiosurgery, and 26 underwent gamma knife radiosurgery. A standardized microcosting methodology was employed to ensure that the identified cost differences would reflect only actual cost differences. Initial treatment costs, using equipment costs per fraction, were €12,288 for microsurgery, €1,547 for LINAC radiosurgery, and €2,412 for gamma knife radiosurgery. Higher initial treatment costs for microsurgery were predominantly due to inpatient stay (€5,321) and indirect costs (€4,350). LINAC and gamma knife radiosurgery were equally expensive when equipment was valued per treatment (€2,198 and €2,412, respectively). Follow-up costs were slightly, but not significantly, higher for microsurgery compared with LINAC and gamma knife radiosurgery. Even though initial treatment costs were over five times higher for microsurgery compared with both radiosurgical treatments, our study gives indications that the relative cost difference may decrease when follow-up costs occurring during the first year after initial treatment are incorporated. This reinforces the need to consider follow-up costs after initial treatment when examining the relative costs of alternative treatments. PMID:20526795

Gamma knife radiosurgery in the treatment of a meningioma in a patient on maintenance hemodialysis: A case report

International Nuclear Information System (INIS)

Matsuo, H.; Nakamura, K.; Hayashi, J.; Nakura, T.; Saruki, K.; Andoh, Y.; Shibazaki, T.; Kubo, K.

1994-01-01

To our knowledge, this is the first report ever on the implementation and results of gamma knife radiosurgery in a regularly dialysed patient. The case presented is that of a 59 year-old female patient with a meningioma. Her initial clinical presentation was with sustained headache. Diagnosis was made by using a brain CT scan and MR imaging. Treatment was performed literally without opening the skull. There was only one complication, namely that of postirradiation brain edema, which developed 19 weeks after the operation, and responded dramatically to steroid administration. This is one of the rare side effects of gamma knife therapy, but does not seem to be related to the fact that the patient was uremic. Gamma knife therapy was successful in this patient and her safety was no more compromised than that of a nonuremic patient undergoing radiosurgery. (authors)

Leksell Gamma Knife radiosurgery of the jugulotympanic glomus tumor: long-term results.

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Liscak, Roman; Urgosik, Dusan; Chytka, Tomas; Simonova, Gabriela; Novotny, Josef; Vymazal, Josef; Guseynova, Khumar; Vladyka, Vilibald

2014-12-01

Glomus tumors usually display indolent behavior, and the effectiveness of radiation in stopping their growth can be assessed after long-term follow-up. Currently only midterm results of radiosurgery are available, so the authors included patients treated by Gamma Knife at least 10 years ago in this study to obtain a perspective of long-term results. During the period from 1992 to 2003, the Gamma Knife was used to treat 46 patients with glomus tumors. The age of the patients ranged from 21 to 79 years (median 56 years). Gamma Knife radiosurgery was the primary treatment in 17 patients (37%). Open surgery preceded radiosurgery in 46% of cases, embolization in 17%, and fractionated radiotherapy in 4%. The volume of the tumor ranged from 0.2 to 24.3 cm(3) (median 3.6 cm(3)). The minimal dose to the tumor margin ranged between 10 and 30 Gy (median 20 Gy). One patient was lost for follow-up after radiosurgery. Clinical follow-up was available in 45 patients and 44 patients were followed with MRI in a follow-up period that ranged from 12 to 217 months (median 118 months). Neurological deficits improved in 19 (42%) of 45 patients and deteriorated in 2 patients (4%). Tumor size decreased in 34 (77%) of 44 patients with imaging follow-up, while an increase in volume was observed in 1 patient (2%) 182 months after radiosurgery and Gamma Knife treatment was repeated. One patient underwent another Gamma Knife treatment for secondary induced meningioma close to the glomus tumor 98 months after initial radiosurgical treatment. Seven patients died 22-96 months after radiosurgery (median 48 months), all for unrelated reasons. Radiosurgery has proved to be a safe treatment with a low morbidity rate and a reliable long-term antiproliferative effect.

Gamma-knife radiosurgery for metastatic brain tumors from primary lung cancer

International Nuclear Information System (INIS)

Uchiyama, Bine; Satoh, Ken; Saijo, Yasuo

1998-01-01

Forty patients with metastatic brain tumors from primary lung cancer underwent radiosurgery (γ-knife). We retrospectively compared their prior treatment history, number of metastatic foci, and performance status, to evaluate the effects of, and indications for, γ-knife therapy. After both the primary and the metastatic tumors were controlled, performance status could be used as an index in the choice of γ-knife therapy. Our results demonstrate that repeated γ-knife radiosurgeries prolonged survival time. Gamma-knife radiosurgery improves quality of life and prognosis of patients with metastatic brain tumors. (author)

A dosimetric comparison of fan-beam intensity modulated radiotherapy with gamma knife stereotactic radiosurgery for treating intermediate intracranial lesions

International Nuclear Information System (INIS)

Ma Lijun; Xia Ping; Verhey, Lynn J.; Boyer, Arthur L.

1999-01-01

Purpose: To compare and evaluate treatment plans for the fan-beam intensity modulated radiotherapy and the Gamma Knife radiosurgery for treating medium-size intracranial lesions (range 4-25 cm 3 ). Methods and Materials: Treatment plans were developed for the Leksell Gamma Knife and a fan-beam inverse treatment planning system for intensity modulated radiotherapy. Treatment plan comparisons were carried out using dose-volume histogram (DVH), tissue-volume ratio (TVR), and maximum dose to the prescription dose (MDPD) ratio. The study was carried out for both simulated targets and clinical targets with irregular shapes and at different locations. Results: The MDPD ratio was significantly greater for the Gamma Knife plans than for the fan-beam IMRT plans. The Gamma Knife plans produced equivalent TVR values to the fan-beam IMRT plans. Based on the DVH comparison, the fan-beam IMRT delivered significantly more dose to the normal brain tissue than the Gamma Knife. The results of the comparison were found to be insensitive to the target locations. Conclusion: The Gamma Knife is better than the fan-beam IMRT in sparing normal brain tissue while producing equivalent tumor dose conformity for treating medium-size intracranial lesions. However, the target dose homogeneity is significantly better for the fan-beam IMRT than for the Gamma Knife

Physics of gamma knife approach on convergent beams in stereotactic radiosurgery

International Nuclear Information System (INIS)

Wu, A.; Lindner, G.; Maitz, A.H.; Kalend, A.M.; Lunsford, L.D.; Flickinger, J.C.; Bloomer, W.D.

1990-01-01

The Presbyterian-University Hospital of Pittsburgh installed the first clinically designated Leksell gamma knife in the U.S. in August 1987. Gamma knife radiosurgery involves stereotactic target localization with the Leksell frame and subsequent closed-skull single-treatment session irradiation of a lesion with multiple highly focused gamma ray beams produced from 60Co sources. The hemispherical array of sources, the large number of small-diameter beams, and the steep dose gradients surrounding a targeted lesion make physical characterization of the radiation field complex. This paper describes the physical features and the operation of the gamma knife as well as the calibration procedures of the very small, well-collimated beams. The results of studies using in-phantom ion chamber, diode, film, and lithium fluoride thermoluminescent dosimetry were all in close agreement. Both single-beam and multiple-beam dose profiles were measured and reported for the interchangeable helmets, which have 4-, 8-, 14-, and 18-mm-diameter collimators. We also describe the dose calculation and treatment planning algorithm in the treatment planning system. Measurements of the accuracy of mechanical and radiation alignment are also performed and discussed

Gamma knife therapy for craniopharyngioma

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Kobayashi, Tatsuya; Kida, Yoshihisa; Tanaka, Takayuki; Yoshida, Kazuo; Yoshimoto, Masayuki; Maezawa, Satoshi; Hasegawa, Toshinori [Komaki Hospital, Aichi (Japan)

1997-01-01

Gamma knife therapy in stereotactic radiosurgery was evaluated as a tool to solve problems raised in therapy for craniopharyngioma. Subjects were 9 childhood patients (<16 y, mean age 9.75 y) and 16 adult patients (mean age 43.9 y), 23 cases of whom had been treated with surgery before gamma knife. Planning of irradiation to the solid part of the tumor was based on their T1-weighted MRI images of 3 mm-thick slice. The mean size of the tumors was 20.7 (9.6-31.2) mm in diameter. The mean central dose of 23.3 (20-30) Gy was irradiated with the mean marginal dose of 11.8 (18-11.3) Gy through the mean shot of 4.8. Results were followed in every 3-6 months by MRI, neurological and endocrinological examinations for 7-52 (mean 23.3) months. Reduction of tumor size including its disappearance (7 cases) were observed in 22 cases (88%) with adverse effects of hypopituitarism (3 cases) and hemianopsia (1). Gamma knife therapy was thus safe and effective. (K.H.)

Gamma Knife radiosurgery in pituitary adenomas: Why, who, and how to treat?

Science.gov (United States)

Castinetti, Frederic; Brue, Thierry

2010-08-01

Pituitary adenomas are benign tumors that can be either secreting (acromegaly, Cushing's disease, prolactinomas) or non-secreting. Transsphenoidal neurosurgery is the gold standard treatment; however, it is not always effective. Gamma Knife radiosurgery is a specific modality of stereotactic radiosurgery, a precise radiation technique. Several studies reported the efficacy and low risk of adverse effects induced by this technique: in secreting pituitary adenomas, hypersecretion is controlled in about 50% of cases and tumor volume is stabilized or decreased in 80-90% of cases, making Gamma Knife a valuable adjunctive or first-line treatment. As hormone levels decrease progressively, the main drawback is the longer time to remission (12-60 months), requiring an additional treatment during this period. Hypopituitarism is the main side effect, observed in 20-40% cases. Gamma Knife is thus useful in the therapeutic algorithms of pituitary adenomas in well-defined indications, mainly low secreting small lesions well identified on magnetic resonance imaging (MRI).

Long-term effects of gamma knife radiosurgery for pediatric craniopharyngioma

International Nuclear Information System (INIS)

Osuka, Koji; Kobayashi, Tatsuya; Kida, Yoshihisa; Tanaka, Takayuki; Yoshida, Kazuo; Hasegawa, Toshinori

2001-01-01

Twenty-one pediatric patients with craniopharyngioma have undergone gamma knife radiosurgery at our facility since May 1991, and we have followed up 10 of these patients for at least 24 months (mean 44.5 months). The patients' ages ranged from 6 to 12 years (mean 8.6 years). Initial presentations were headache in 7 patients, decreased visual acuity in 8, visual field deficit in 5, hypopituitarism in 7, and diabetes insipidus in 3. Prior to radiosurgery, surgical procedures had been performed in 8 patients, conventional radiotherapy in 1, and chemotherapy in 1. Mean tumor diameter was 17.4 mm, and treatment was by gamma knife, with mean maximum and marginal doses of 25.4 Gy and 13.3 Gy, respectively. Follow-up MRI revealed good tumor control (partial response+complete response) in 7 of the 10 patients, with neither further neurological nor endocrinological deterioration. Two patients showed tumor shrinkage for 60 months and 46 months, respectively, after radiosurgery, while, thereafter, tumor gradually recurred at the side of the optic nerve. In one patient, rapid growth of the cyst was observed 6 months after radiosurgery. Gamma knife radiosurgery for pediatric craniopharyngioma is considered to be a safe and effective treatment after microsurgical tumor removal. In cases in which total removal is impossible, it is important to detach the tumor from the optic nerve and to reduce the tumor volume for gamma knife radiosurgery after microsurgery. If the tumor has a cystic component, this should be removed at the time of surgery. (author)

Long-term effects of gamma knife radiosurgery for pediatric craniopharyngioma

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Osuka, Koji; Kobayashi, Tatsuya; Kida, Yoshihisa; Tanaka, Takayuki; Yoshida, Kazuo; Hasegawa, Toshinori [Komaki City Hospital, Aichi (Japan)

2001-02-01

Twenty-one pediatric patients with craniopharyngioma have undergone gamma knife radiosurgery at our facility since May 1991, and we have followed up 10 of these patients for at least 24 months (mean 44.5 months). The patients' ages ranged from 6 to 12 years (mean 8.6 years). Initial presentations were headache in 7 patients, decreased visual acuity in 8, visual field deficit in 5, hypopituitarism in 7, and diabetes insipidus in 3. Prior to radiosurgery, surgical procedures had been performed in 8 patients, conventional radiotherapy in 1, and chemotherapy in 1. Mean tumor diameter was 17.4 mm, and treatment was by gamma knife, with mean maximum and marginal doses of 25.4 Gy and 13.3 Gy, respectively. Follow-up MRI revealed good tumor control (partial response+complete response) in 7 of the 10 patients, with neither further neurological nor endocrinological deterioration. Two patients showed tumor shrinkage for 60 months and 46 months, respectively, after radiosurgery, while, thereafter, tumor gradually recurred at the side of the optic nerve. In one patient, rapid growth of the cyst was observed 6 months after radiosurgery. Gamma knife radiosurgery for pediatric craniopharyngioma is considered to be a safe and effective treatment after microsurgical tumor removal. In cases in which total removal is impossible, it is important to detach the tumor from the optic nerve and to reduce the tumor volume for gamma knife radiosurgery after microsurgery. If the tumor has a cystic component, this should be removed at the time of surgery. (author)

Role of the Gamma Knife in the treatment of large lesions.

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Helenowski, T K; Pothiawala, B

1993-01-01

A virtual reality dose planning system, DosePlan(R), has been devised to increase the speed and accuracy of multishot dose planning for larger lesions treated in the Leksell Gamma Knife. The accuracy of the dose-planning was sophisticated further by a number of additional quality assurance procedures during the radiological definition of the target. Some aspects of the experience in Chicago are described in respect to the first 600 patients treated in the Gamma Knife. Only 35.4% had a maximum diameter of 35 mm or less. The size of the lesions required multiple-shot dose plans, with an average of 8.9 shots per patient and a tendency to an increasing number of shots with increasing experience. Some specific cases are illustrated to show the effectiveness of the dose-planning methods described.

Effects of gamma knife radiosurgery for pediatric craniopharyngiomas

International Nuclear Information System (INIS)

Tanaka, Takayuki; Kobayashi, Tatsuya; Kida, Yoshihisa

1996-01-01

Seven cases of pediatric craniopharyngiomas have been treated by gamma knife and followed-up for a mean 24.1 months between May, 1991 and March, 1995. They included 4 boys and 3 girls with a mean age of 8.9 years. Initial signs and symptoms were: headaches in 2 cases, decrease in visual acuity in 6 cases, visual field deficit in 5 cases, hypopituitary function in 5 cases, and diabetes insipidus in one case. Prior to the radiosurgery, surgical therapy had been performed in 7 cases, conventional radiotherapy in one case, and chemotherapy in one case. Tumor were located in the chiasmal region in 3 cases and the suprasellar region in 4 cases. Mean tumor diameter was 18.5 mm. Mean and marginal irradiation dosages were 25.9 Gy and 13.4 Gy. Repeated MRI indicated marked shrinkage of tumors was obtained in all 7 cases. Follow up showed neurological signs and symptoms improved in 3 cases and remained unchanged in 4 cases, without any side-effects. Hormonal study indicated TSH decreased about one year after gamma knife radiosurgery. It is considered that gamma knife radiosurgery will be a safe and effective treatment for pediatric craniopharyngiomas in combination with microsurgery. (author)

Effect of Gamma Knife Surgery for Uveal Melanoma

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Kim, Gi Hong [Det. of Neurosurgery, Yensei Medical Center,Seoul (Korea, Republic of); Cho, Jung Hee; Park, Jae Il [Dept. of Radition Oncology, Yensei Medical Center, Seoul (Korea, Republic of)

1997-11-15

The optimal management of uveal melanoma is still a matter of controversy. To determine the effect of Gamma Knife surgery for patients with uveal malanoma. The authors reviewed the results of 5 patients underwent Gamma Knife surgery between Sep. 1993 and Dec. 1996. The mean age was 60.7 years ranging from 42.5 to 76.5 years. Median follow-up was 13.29 months and the patient with follow up period more than 6 months was 4. The mean tumor volume was 3442 mm{sup 3} (mean diameter 15.3 mm) and all patients were irradiated with a mean maximum dose of 74 Gy (range 60-80 Gy), using the 50% isodose. After Gamma Knife surgery. One patient showed complete disappearance in tumor size with follow-up 32 months, One enucleation due to progression, and 2 no interval change. In regard to vision, one patient blind. One enucleation, and 2 patients had no interval change. According to our experiences, Gamma Knife surgery for uveal melanoma be able to achieve local tumor control, spare the eyeball, and have possibility of save vision.

Research about combination of Gamma Knife and cobalt-60 radiation therapy to treat hypophysoma

International Nuclear Information System (INIS)

Xing Yueming; Zhao Xinping; Song Xiang; Wu Wei; Huang Bai

2003-01-01

Objective: To probe the therapeutic effectiveness of combination of Gamma Knife and cobalt-60 radiotherapy. Methods: 80 Hypophysoma patients who have been randomly grouped into two groups. Combination of Gamma Knife and cobalt-60 radiotherapy group and single Gamma knife group. Results: The therapeutic effectiveness of combination of Gamma Knife and cobalt-60 radiation therapy group was higher than that of single Gamma Knife group. Conclusion: The hospital that treat Hypophysoma with single Gamma Knife should add cobalt-60 radiotherapy in order to increase the local Hypophysoma dose

A formalism for independent checking of Gamma Knife dose calculations

International Nuclear Information System (INIS)

Tsai Jensan; Engler, Mark J.; Rivard, Mark J.; Mahajan, Anita; Borden, Jonathan A.; Zheng Zhen

2001-01-01

For stereotactic radiosurgery using the Leksell Gamma Knife system, it is important to perform a pre-treatment verification of the maximum dose calculated with the Leksell GammaPlan[reg] (D LGP ) stereotactic radiosurgery system. This verification can be incorporated as part of a routine quality assurance (QA) procedure to minimize the chance of a hazardous overdose. To implement this procedure, a formalism has been developed to calculate the dose D CAL (X,Y,Z,d av ,t) using the following parameters: average target depth (d av ), coordinates (X,Y,Z) of the maximum dose location or any other dose point(s) to be verified, 3-dimensional (3-dim) beam profiles or off-center-ratios (OCR) of the four helmets, helmet size i, output factor O i , plug factor P i , each shot j coordinates (x,y,z) i,j , and shot treatment time (t i,j ). The average depth of the target d av was obtained either from MRI/CT images or ruler measurements of the Gamma Knife Bubble Head Frame. D CAL and D LGP were then compared to evaluate the accuracy of this independent calculation. The proposed calculation for an independent check of D LGP has been demonstrated to be accurate and reliable, and thus serves as a QA tool for Gamma Knife stereotactic radiosurgery

The treatment for acoustic neuromas. Indication and results of gamma knife radiosurgery and surgery

International Nuclear Information System (INIS)

Iwai, Yoshiyasu; Yamanaka, Kazuhiro; Uyama, Taichi; Morikawa, Toshie; Honda, Yuji; Matsusaka, Yasuhiro; Komiyama, Masaki; Yasui, Toshihiro

2004-01-01

We evaluated the treatment results of acoustic neuromas in the era of radiosurgery. We treated acoustic neuromas using the following strategy. Small to medium size tumors (below 3 cm) were treated by gamma knife radiosurgery and large tumors (above 3 cm) were treated using a combination of surgery and radiosurgery. Using gamma knife radiosurgery we were able to achieve 96.4% of clinical tumor growth control with 0.7% incidence of trigeminal neuropathy (without new facial neuropathy). We used low dose radiosurgery (average tumor marginal dose 11.8 Gy) with a follow-up of an average of 54 months. For the 17 patients with large tumors treated by the combination of surgery and radiosurgery who could be followed up for over 24 months after radiosurgery, we were able to preserve normal facial function (House-Brackmann grade I-II) in 70.6% of the patients after subtotal removal. High clinical tumor growth control for residual tumor was achieved in 94.1% of subjects with an average of 40 months follow-up. By using this strategy, the treatment outcome for acoustic neuroma is improved from the standpoint of functional outcome and maintaining the patient's quality of life. (author)

γTools: A modular multifunction phantom for quality assurance in GammaKnife treatments.

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Calusi, Silvia; Noferini, Linhsia; Marrazzo, Livia; Casati, Marta; Arilli, Chiara; Compagnucci, Antonella; Talamonti, Cinzia; Scoccianti, Silvia; Greto, Daniela; Bordi, Lorenzo; Livi, Lorenzo; Pallotta, Stefania

2017-11-01

We present the γTools, a new phantom designed to assess geometric and dosimetric accuracy in Gamma Knife treatments, together with first tests and results of applications. The phantom is composed of two modules: the imaging module, a regular grid of 1660 control points to evaluate image distortions and image registration result and the dosimetry module for delivered dose distribution measurements. The phantom is accompanied by a MatLab routine for image distortions quantification. Dose measurement are performed with Gafchromic films fixed between two inserts and placed in various positions and orientations inside the dosimetry module thus covering a volume comparable to the full volume of a head. Tests performed to assess the accuracy and precision of the imaging module demonstrated sub-millimetric values. As an example of possible applications, the phantom was employed to measure image distortions of two MRI scanners and to perform dosimetric studies of single shots delivered to homogeneous and heterogeneous materials. Due to the phantom material, the measured absolute dose do not correspond to the planned dose; doses comparisons are thus carried out between normalized dose distributions. Finally, an end-to-end test was carried out in the treatment of a neuroma-like target which resulted in a 100% gamma passing rate (2% local, 2 mm) and a distance between the real target perimeter and the prescription isodose centroids of about 1 mm. The tests demonstrate that the proposed phantom is suitable to assess both the geometrical and relative dosimetric accuracy of Gamma Knife radiosurgery treatments. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Shielding requirements on-site loading and acceptance testing on the Leksell gamma knife

International Nuclear Information System (INIS)

Maitz, A.H.; Lunsford, L.D.; Wu, A.; Lindner, G.; Flickinger, J.C.

1990-01-01

On August 14, 1987, the first stereotactic radiosurgical procedure using the gamma knife was performed in North America. Located in a self-contained radiosurgical suite in the basement of Presbyterian-University Hospital in Pittsburgh, Pennsylvania. This device uses 201 highly focused beams 60Co for the single-treatment closed-skull irradiation of brain lesions localized by stereotactic techniques (radiosurgery). One hundred and fifty-two patients with intracranial arteriovenous malformations or brain tumors were treated in the first year of operation. The Presbyterian University Hospital of Pittsburgh gamma knife is the first such unit in which the 60Co sources were loaded on-site. This effort required us to solve some difficult and unusual problems encountered during site preparation, delivery, and loading of the unit in a busy hospital setting. The solutions developed enabled installation and use of the gamma knife with minimal disruption of hospital activities while maintaining acceptable levels of exposure to radiation. Environmental surveys performed during the loading of the 201 radioactive sources (total, 219 TBq) confirmed that on-site loading is possible and practical. Our experience in the design, construction, and implementation of the first North American gamma knife supports the practicality and safety of on-site loading and may be of value in the planning and development of future gamma knife installations

Clinical efficacy of gamma knife and surgery treatment of mesial temporal lobe epilepsy and their effects on EF-Tumt and EF-Tsmt expression.

Science.gov (United States)

Wang, X-Q; Zhang, X-D; Han, Y-M; Shi, X-F; Lan, Z-B; Men, X-X; Pan, Y-W

2017-04-01

To study the clinical efficacy of gamma knife and surgery treatment of mesial temporal lobe epilepsy (MTLE) and their effects on EF-Tumt and EF-Tsmt expression. The data of 78 cases of MTLE patients treated in our hospital from April 2011 to March 2013 were retrospectively analyzed. The patients were divided into two groups according to the treatment methods: the surgery group (including 41 cases) and the gamma knife group (including 37 cases). The clinical efficacy, the occurrence and recurrence of complications were evaluated, respectively; meanwhile, the expression of the EF-Tumt protein and EF-Tsmt protein in brain tissue were analyzed. The difference between the efficacy rate of the two groups showed no statistical significance (χ2=0.960, p>0.05). The complication rate of the gamma knife group was significantly lower than that of the control group (χ2=6.430, pknife group was significantly lower than that of the patients in the surgery group (p>0.05). Within the two groups, the positive expression granum of EF-Tsmt protein and EF-Tumt protein of the two groups after treatment were significantly lower than that before treatment (pknife group was obviously more than that of the patients in the surgery group (p0.05). Before and after treatment within the group, the positive cell of EF-Tsmt protein and EF-Tumt protein of the two groups of patients after treatment were significantly lower than that before treatment (p0.05). Both surgery and gamma knife could treat MTLE effectively, and the efficacy may be related to the ability to reduce the expression of EF-Tsmt protein and EF-Tumt protein in brain tissue.

Dosimetric calculations by Monte Carlo for treatments of radiosurgery with the Leksell Gamma Knife, homogeneous and non homogeneous cases

International Nuclear Information System (INIS)

Rojas C, E.L.; Lallena R, A.M.

2004-01-01

In this work dose profiles are calculated that are obtained modeling treatments of radiosurgery with the Leksell Gamma Knife. This was made with the simulation code Monte Carlo Penelope for an homogeneous mannequin and one not homogeneous. Its were carried out calculations with the irradiation focus coinciding with the center of the mannequin as in near areas to the bone interface. Each one of the calculations one carries out for the 4 skull treatment that it includes the Gamma Knife and using a model simplified of their 201 sources of 60 Co. It was found that the dose profiles differ of the order of 2% when the isocenter coincides with the center of the mannequin and they ascend to near 5% when the isocenter moves toward the skull. (Author)

MCNP-based computational model for the Leksell gamma knife.

Science.gov (United States)

Trnka, Jiri; Novotny, Josef; Kluson, Jaroslav

2007-01-01

We have focused on the usage of MCNP code for calculation of Gamma Knife radiation field parameters with a homogenous polystyrene phantom. We have investigated several parameters of the Leksell Gamma Knife radiation field and compared the results with other studies based on EGS4 and PENELOPE code as well as the Leksell Gamma Knife treatment planning system Leksell GammaPlan (LGP). The current model describes all 201 radiation beams together and simulates all the sources in the same time. Within each beam, it considers the technical construction of the source, the source holder, collimator system, the spherical phantom, and surrounding material. We have calculated output factors for various sizes of scoring volumes, relative dose distributions along basic planes including linear dose profiles, integral doses in various volumes, and differential dose volume histograms. All the parameters have been calculated for each collimator size and for the isocentric configuration of the phantom. We have found the calculated output factors to be in agreement with other authors' works except the case of 4 mm collimator size, where averaging over the scoring volume and statistical uncertainties strongly influences the calculated results. In general, all the results are dependent on the choice of the scoring volume. The calculated linear dose profiles and relative dose distributions also match independent studies and the Leksell GammaPlan, but care must be taken about the fluctuations within the plateau, which can influence the normalization, and accuracy in determining the isocenter position, which is important for comparing different dose profiles. The calculated differential dose volume histograms and integral doses have been compared with data provided by the Leksell GammaPlan. The dose volume histograms are in good agreement as well as integral doses calculated in small calculation matrix volumes. However, deviations in integral doses up to 50% can be observed for large

St. Joseph's Hospital Barrow Neurological Institute stereitatic radiotherapy experience comparison of Gamma Knife and CyberKnife

International Nuclear Information System (INIS)

Kresl, J.J.

2006-01-01

The clinical utilisation stereotactic radiotherapy continues to increase in breadth and scope within the medical community. However, no single standard treatment platform exists for the delivery of stereotactic radiotherapy treatments. This is because although there are several commercially available platforms capable of delivering stereotactic radiotherapy treatments, each platform has unique abilities and limitations. The most widely used stereotactic radiotherapy system for intracranial treatments is the Gamma Knife. The first image guided robotic stereotactic radiotherapy system enabling body stereotactic radiotherapy is the CyberKnife. Both are available at the Barrow Neurological Institute. We describe our experience with the complementary use of these two distinct treatment platforms. This permits us to make a meaningful comparison and to detail their contrasting advantages and disadvantages for state of the art for stereotactic radiotherapy. (author)

Comparison of full width at half maximum and penumbra of different Gamma Knife models.

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Asgari, Sepideh; Banaee, Nooshin; Nedaie, Hassan Ali

2018-01-01

As a radiosurgical tool, Gamma Knife has the best and widespread name recognition. Gamma Knife is a noninvasive intracranial technique invented and developed by Swedish neurosurgeon Lars Leksell. The first commercial Leksell Gamma Knife entered the therapeutic armamentarium at the University of Pittsburgh in the United States on August 1987. Since that time, different generation of Gamma Knife developed. In this study, the technical points and dosimetric parameters including full width at half maximum and penumbra on different generation of Gamma Knife will be reviewed and compared. The results of this review study show that the rotating gamma system provides a better dose conformity.

The role of neuropsychology in medical treatment using the Gamma Knife

International Nuclear Information System (INIS)

Koran, M.

1994-01-01

Patients waiting for or undergoing surgery with the Leksell Gamma Knife are mostly under emotional stress. The patient's subjective feelings are investigated by interviewing and by psychological examination using questionnaires. This serves as the basis for psychoprophylaxis and psychotherapy. Experience gained in medical practice is described. 20 refs

Dosimetry characteristics of the Leksell gamma knife for stereotactic radiosurgery

International Nuclear Information System (INIS)

Wu, A.; Lindner, G.; Maitz, A.; Smarra, N.; Turco, R.F.; Kalend, A.M.; Lunsford, L.D.; Flickinger, J.C.; Bloomer, W.D.

1988-01-01

Gamma knife radiosurgery refers to the treatment procedure that delivers very high dose to a small brain lesion with 201 highly focused beams of Co-60. The hemispheric array of these multiple sources with the sizes of beams ranging from 4, 8, 14, to 18 mm makes the determination of dosimetry characteristics of the radiation field very complex. This paper describes the structures, operations, and dose characteristics of gamma knife. Dosimetry measurements were made using ion chamber, TLD, diode, and films to calibrate the dose outputs of the combination of 201 beams of 4, 8, 14, or 18 mm in diameter irradiating from various directions. Results of measured isodose distribution and dose profiles for the various diameter beams are also presented

Dosimetric calculations by Monte Carlo for treatments of radiosurgery with the Leksell Gamma Knife, homogeneous and non homogeneous cases; Calculos dosimetricos por Monte Carlo para tratamientos de radiocirugia con el Leksell Gamma Knife, casos homogeneo y no homogeneo

Energy Technology Data Exchange (ETDEWEB)

Rojas C, E.L. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Lallena R, A.M. [Universidad de Granada (Spain)

2004-07-01

In this work dose profiles are calculated that are obtained modeling treatments of radiosurgery with the Leksell Gamma Knife. This was made with the simulation code Monte Carlo Penelope for an homogeneous mannequin and one not homogeneous. Its were carried out calculations with the irradiation focus coinciding with the center of the mannequin as in near areas to the bone interface. Each one of the calculations one carries out for the 4 skull treatment that it includes the Gamma Knife and using a model simplified of their 201 sources of {sup 60} Co. It was found that the dose profiles differ of the order of 2% when the isocenter coincides with the center of the mannequin and they ascend to near 5% when the isocenter moves toward the skull. (Author)

Gamma Knife Radiosurgery for Acromegaly

Directory of Open Access Journals (Sweden)

John D. Rolston

2012-01-01

Full Text Available Acromegaly is debilitating disease occasionally refractory to surgical and medical treatment. Stereotactic radiosurgery, and in particular Gamma Knife surgery (GKS, has proven to be an effective noninvasive adjunct to traditional treatments, leading to disease remission in a substantial proportion of patients. Such remission holds the promise of eliminating the need for expensive medications, along with side effects, as well as sparing patients the damaging sequelae of uncontrolled acromegaly. Numerous studies of radiosurgical treatments for acromegaly have been carried out. These illustrate an overall remission rate over 40%. Morbidity from radiosurgery is infrequent but can include cranial nerve palsies and hypopituitarism. Overall, stereotactic radiosurgery is a promising therapy for patients with acromegaly and deserves further study to refine its role in the treatment of affected patients.

Gamma knife radiosurgery for secreting pituitary tumors

International Nuclear Information System (INIS)

Noren, G.; Jackson, I.M.D.; Chougule, P.; Zheng, Z.; Epstein, M.H.

1998-01-01

Transsphenoidal surgery usually represents first line treatment for pituitary adenomas with the aim of removing the tumor, decompressing the optic apparatus and, in secreting tumors, eliminating the hypersecretion. Gamma Knife radiosurgery is indicated for tumor remnants or recurrences in or above the sella including those invading the cavernous sinus and also as initial treatment in patients who are unable to tolerate an open surgical procedure and where medication has failed. In this study, the target definition was retrospectively studied and when necessary corrected in 10 acromegalic patients, 8 with Cushing's disease, and 12 with prolactinomas undergoing Gamma Knife radiosurgery. The dose plan was analyzed and the volume of the target covered by a minimum of 15, 20, 25, 30 and 35 Gy was estimated. A dose/volume profile for each treatment was created and correlated to the endocrinological and clinical outcome. Cure, according to strict endocrinological criteria, was seen in 6 of the acromegalic patients, in 2 of the patients with ACTH hypersecretion, and in 2 of the patients with prolactinomas. Analysis of these profiles, also for the patients with partial effect, show that a minimum radiation dose of 20 Gy may be adequate to eliminate the hypersecretion in acromegalic patients whereas a dose of at least 25 Gy may be required in patients with Cushing's disease and prolactinoma. (author)

Arteriovenous malformations of the brain treated with gamma knife

International Nuclear Information System (INIS)

Tanaka, Takayuki; Kobayashi, Tatsuya; Kida, Yoshihisa

1994-01-01

The early effects of treatment with gamma knife radiosurgery for intracranial arteriovenous malformations (AVM) were investigated in 25 children, 15 boys and 10 girls, aged 2 to 15 years (mean 11). Neurological signs were hemiparesis in 10, mental retardation in 2, etc. Initial events were hemorrhage in 23 (92%) and epilepsy in 2 patients. The locations of AVM were parietal lobe in 6, thalamus in 4 patients, etc. The mean diameter of the nidus was 1.97 cm, and the volume was under 10 cm 3 in 21 cases. Of the 25 patients were classified as Grade II or higher by the Spetzler and Martin grading system. The mean maximum dose was 36.2 Gy, and marginal dose of 20.2 Gy with a mean isocenter of 3.2 were used. Follow-up angiography was performed more than one year after treatment in 7 patients. Five of the 7 (71.4%) showed complete obliteration of the AVM. No patients has had rebleeding after treatment so far, but one patient has had hemiparesis due to radiation-induced edema. Stereotactic radiosurgery by gamma knife is a preventive treatment of intracranial AVM in childhood. (author)

Optimization of Gamma Knife treatment planning via guided evolutionary simulated annealing

International Nuclear Information System (INIS)

Zhang Pengpeng; Dean, David; Metzger, Andrew; Sibata, Claudio

2001-01-01

We present a method for generating optimized Gamma Knife trade mark sign (Elekta, Stockholm, Sweden) radiosurgery treatment plans. This semiautomatic method produces a highly conformal shot packing plan for the irradiation of an intracranial tumor. We simulate optimal treatment planning criteria with a probability function that is linked to every voxel in a volumetric (MR or CT) region of interest. This sigmoidal P + parameter models the requirement of conformality (i.e., tumor ablation and normal tissue sparing). After determination of initial radiosurgery treatment parameters, a guided evolutionary simulated annealing (GESA) algorithm is used to find the optimal size, position, and weight for each shot. The three-dimensional GESA algorithm searches the shot parameter space more thoroughly than is possible during manual shot packing and provides one plan that is suitable to the treatment criteria of the attending neurosurgeon and radiation oncologist. The result is a more conformal plan, which also reduces redundancy, and saves treatment administration time

Acute necrosis after Gamma Knife surgery in vestibular schwannoma leading to multiple cranial nerve palsies.

Science.gov (United States)

Kapitza, Sandra; Pangalu, Athina; Horstmann, Gerhard A; van Eck, Albert T; Regli, Luca; Tarnutzer, Alexander A

2016-08-01

We discuss a rare acute complication after Gamma Knife therapy (Elekta AB, Stockholm, Sweden) in a single patient. A 52-year-old woman presented with vertigo, facial weakness and hearing loss emerging 48hours following Gamma Knife radiosurgery for a right-sided vestibular schwannoma. Neurological examination 6days after symptom onset showed right-sided facial palsy, spontaneous left-beating nystagmus and pathologic head-impulse testing to the right. Pure-tone audiogram revealed right-sided sensorineural hearing loss. A diagnosis of acute vestibulocochlear and facial neuropathy was made. Brain MRI demonstrated focal contrast sparing within the schwannoma, likely related to acute radiation necrosis. Acute multiple cranial neuropathies of the cerebellopontine angle after Gamma Knife treatment should raise suspicion of acute tissue damage within the schwannoma and should result in urgent MRI. Treatment with steroids may be considered based on accompanying swelling and edema. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of timer end-effects on Gamma knife (Type B) treatment

International Nuclear Information System (INIS)

Baba, Sadaaki; Ito, Teruo; Toyoda, Tatsuya; Wakamatsu, Osamu; Machida, Toru

2004-01-01

We investigated the influence of timer end-effects retrospectively in cases treated with Gamma knife (Type B) in the first year and in the fifth year after installation. Objects were 113 cases from April 1997 to December 1997 and 230 cases between January 2001 and December 2001. The influence of timer end-effects was calculated in the following formula: influence of timer end-effects=Σ (timer end-effects/shot time)/(number of lesions x number of shots). Ten factors such as the output at the center of polystyrene sphere phantom, the number of lesions, the number of shots, the delivered maximum absorbed dose, total irradiation time and the frequency in the use of each collimator helmet were examined as factors of the influence. The average values of timer end-effects were 4.7±0.27, 4.3±0.27, 3.6±0.24 and 3.5±0.29%/min. for 18, 14, 8 and 4 mm collimator helmets, respectively and depended on field size. We believe that the unit '%/min.' must be accepted instead of '%'. Gamma knife treatment is stereotactic radiosurgery and 40-50 Gy is irradiated within several hours with about ten shots. So the influence of timer end-effects was calculated 0.82±0.80% in 1997 and 0.51±0.41% in 2001 on average. These data suggest that there was little influence on the treatment. These figures were average values per lesion, so the influence may be more complicated in each part of lesions. The difference between the influence of timer end-effects in 1997 and 2001 was considered to be caused by the elongation of shot time according to Cobalt-60 decay, the reduction of the number of shots by frequent use of 14 mm collimator helmet, and the restriction of the number of treated lesions. (author)

Use of the Leksell Gamma Knife in the Treatment of Prolactinoma Patients

Czech Academy of Sciences Publication Activity Database

Ježková, J.; Hána, V.; Kršek, M.; Weiss, V.; Vladyka, V.; Liščák, R.; Vymazal, J.; Pecen, Ladislav; Marek, J.

2009-01-01

Roč. 70, č. 5 (2009), s. 732-741 ISSN 0300-0664 Institutional research plan: CEZ:AV0Z10300504 Keywords : prolactinoma * Leksell gamma knife * time to prolactin normalization analysis Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 3.201, year: 2009

Gamma Knife Radiosurgery for Choroidal Hemangioma

International Nuclear Information System (INIS)

Kim, Yun Taek; Kang, Se Woong; Lee, Jung-Il

2011-01-01

Purpose: Patients with choroidal hemangioma (CH), a benign ocular hamartoma, frequently presents with visual disturbance as a result of exudative retinal detachment (RD), which originates in subretinal fluid accumulation. We report our experience using the Leksell Gamma Knife in the management of symptomatic CH. Methods and Materials: Seven patients with symptomatic CH (circumscribed form in 3 patients and diffuse form in 4) were treated with the Leksell Gamma Knife at our institution during a 7-year period. All patients presented with exudative RD involving the macula that resulted in severe visual deterioration. The prescription dose to the target margin was 10 Gy in all cases. The mean tumor volume receiving the prescription dose was 536 mm 3 (range, 151–1,057). The clinical data were analyzed in a retrospective fashion after a mean follow-up of 34.4 months (range, 9–76). Results: The resolution of exudative RD was achieved within 6 months, and the visual acuity of the affected eye had improved at the latest follow-up examination (p = .018) in all patients. No recurrence of exudative RD occurred. Thinning of the CHs was observed in most patients; however, symptomatic radiation toxicity had not developed in any of the patients. Conclusion: Symptomatic CHs can be safely and effectively managed with Gamma Knife radiosurgery using a marginal dose of 10 Gy.

Gamma Knife Radiosurgery for Choroidal Hemangioma

Energy Technology Data Exchange (ETDEWEB)

Kim, Yun Taek; Kang, Se Woong [Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Lee, Jung-Il, E-mail: jilee@skku.edu [Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

2011-12-01

Purpose: Patients with choroidal hemangioma (CH), a benign ocular hamartoma, frequently presents with visual disturbance as a result of exudative retinal detachment (RD), which originates in subretinal fluid accumulation. We report our experience using the Leksell Gamma Knife in the management of symptomatic CH. Methods and Materials: Seven patients with symptomatic CH (circumscribed form in 3 patients and diffuse form in 4) were treated with the Leksell Gamma Knife at our institution during a 7-year period. All patients presented with exudative RD involving the macula that resulted in severe visual deterioration. The prescription dose to the target margin was 10 Gy in all cases. The mean tumor volume receiving the prescription dose was 536 mm{sup 3} (range, 151-1,057). The clinical data were analyzed in a retrospective fashion after a mean follow-up of 34.4 months (range, 9-76). Results: The resolution of exudative RD was achieved within 6 months, and the visual acuity of the affected eye had improved at the latest follow-up examination (p = .018) in all patients. No recurrence of exudative RD occurred. Thinning of the CHs was observed in most patients; however, symptomatic radiation toxicity had not developed in any of the patients. Conclusion: Symptomatic CHs can be safely and effectively managed with Gamma Knife radiosurgery using a marginal dose of 10 Gy.

Salvage gamma knife radiosurgery in the management of dysembryoplastic neuroepithelial tumors

DEFF Research Database (Denmark)

Sinclair, Georges; Martin, Heather; Shamikh, Alia

2017-01-01

BACKGROUND: Dysembryoplastic neuroepithelial tumors (DNT/DNET) are rare epileptogenic tumors. Microsurgery remains the best treatment option, although case reports exist on the use of gamma knife radiosurgery (GKRS) in selected cases. We investigated the long-term outcome of GKRS-treated DNTs...

Intractable trigeminal neuralgia: A single institution experience in 26 patients treated with stereotactic gamma knife radiosurgery

International Nuclear Information System (INIS)

Mark, Rufus J.; Duma, Christopher M.; Jacques, Dean B.; Kopyov, Oleg V.; Copcutt, Brian

1996-01-01

Purpose: In patients with trigeminal neuralgia, severe pain can persist, or recur despite aggressive medical management and open surgery. Recently, Gamma Knife radiosurgery has been used with promising results. We report on our series of 26 patients with intractable trigeminal neuralgia treated with stereotactic Gamma Knife radiosurgery. Materials and Methods: Between 1991 and 1995, 26 patients with intractable trigeminal neuralgia were treated at our institution using stereotactic Gamma Knife radiosurgery. Medical management had failed in all cases. In addition, 13 patients underwent a total of 20 open surgeries, with transient, or no pain relief. There were 19 females, and 7 males. Patient ages ranged from 37 to 87 years, with a median of 74 years. All patients were treated with a 201 source Cobalt-60 Gamma Knife unit. All patients underwent placement of the Leksell frame, followed by MRI scanning and computer treatment planning. The target in all patients was the fifth cranial nerve root entry zone into the brainstem. Twenty-five patients received between 64.3 to 70 Gy prescribed to Dmax in one shot. One patient received 120 Gy to Dmax in one shot. The 4 mm collimator was used in 22 cases, and the 8 mm in 4 cases. Follow-up ranged from 5 to 55 months, with a median of 19 months. Complete resolution (CR) of pain was scored when the patient reported being pain free off all medication. Partial resolution (PR) was scored when the patient reported > 50% pain reduction after Gamma Knife treatment. Results: At last follow-up, 84.6% ((22(26))) reported CR or PR of pain after Gamma Knife treatment. Forty-two percent ((11(26))) of patients reported CR, and 42%((11(26))) reported PR of pain. There was a dose response. In patients receiving < 70 Gy, 25% ((3(12))) reported CR, while 57% ((8(14))) of those receiving ≥ 70 Gy reported CR. Complications occurred in two (8%) patients. One patient developed transient numbness of the face after 70 Gy, and a second patient

Role of gamma knife radiosurgery in craniopharyngioma

Directory of Open Access Journals (Sweden)

Ashis Patnaik

2013-01-01

Full Text Available Craniopharyngiomas continue to be a challenge to manage, due to difficulty in complete excision and frequent recurrences. The management protocol remains controversial. They have a tendency to invade the normal brain tissues around them and due to their position in suprasellar region in close relationship with vital structures like optic apparatus, pituitary-hypothalamic axis, complete removal is often not feasible without causing serious morbidity and mortality. In this scenario, sub-total excision seems to be a better alternative, which is plagued by early and frequent recurrences. Radiotherapy has been used for increasing the progression free survival and to improve the overall quality of life. Recently Gamma knife radiosurgery has evolved as a promising technique of radiating the residual or recurrent tumor in a single session with great accuracy and precision. This helps in maximizing the radiation dose to the tumor with steep dose fall off to the surrounding tissue, and hence there is better control of the tumor and minimal radiation exposure to surrounding normal, vital brain tissues. We discuss the current strategies of Gamma knife treatment for craniopharyngioma and review the literature.

A case of neurofibromatosis developing facial paralysis following treatment with a gamma knife

Energy Technology Data Exchange (ETDEWEB)

Hosomi, Yoshikazu [Kobe Rosai Hospital (Japan)

2002-12-01

Neurofibromatosis is generally classified into types I and II: the latter may be life-threatening when the acoustic nerve tumor becomes enlarged. The author reports on a patient with bilateral acoustic nerve tumors, as well as large tumors at the neck and sacral regions, who developed facial nerve paralysis following surgery in which a gamma knife was used. The patient, a 30-year-old woman with no family history of neurofibromatosis, had a prominent neurofibroma at the pharyngeal region surgically removed when she was about 23. The procedure left her with dysfunctions of the vocal cords and lingual movements. At the age of 30 (March 2001), a tumor originating at S1 of the sacral nerve plexus was removed, which caused her leg movements to be restricted. Later, an acoustic nerve tumor was found to have enlarged; and in July 2001, the left acoustic nerve tumor was extirpated by using a gamma knife. Starting in early 2002, her left facial movements appeared to be compromised but during the follow-up observation period, she regained the movements. Patients with neurofibromatosis are often plagued by the development of multiple tumors and surgical sequelae. One is reminded that it is necessary to plan treatment with sufficient consideration given to quality of life (QOL) (including the problem of an acoustic nerve tumor that may develop in future) as well as individual patients wishes. (author)

A simplified model of the source channel of the Leksell GammaKnife tested with PENELOPE

OpenAIRE

Al-Dweri, Feras M. O.; Lallena, Antonio M.; Vilches, Manuel

2004-01-01

Monte Carlo simulations using the code PENELOPE have been performed to test a simplified model of the source channel geometry of the Leksell GammaKnife$^{\\circledR}$. The characteristics of the radiation passing through the treatment helmets are analysed in detail. We have found that only primary particles emitted from the source with polar angles smaller than 3$^{\\rm o}$ with respect to the beam axis are relevant for the dosimetry of the Gamma Knife. The photons trajectories reaching the out...

Gamma knife radiosurgery for endocrine-inactive pituitary adenomas

International Nuclear Information System (INIS)

Liscak, R.; Vladyka, V.; Simonova, G.; Marek, J.; Vymazal, J.

2007-01-01

The goal of nonsecreting pituitary adenoma radiosurgery is to halt tumor growth and to maintain normal performance of the hypophysis and the functionally important structures around the sella. The effectiveness of gamma knife radiosurgery was evaluated. Over a period of 10 years (1993-2003), 140 patients with nonsecreting pituitary adenoma were treated by Leksell gamma knife at our Centre. Seventy-nine of them were followed up for longer than 3 years. Their age range was 24-73 years, with a median of 54 years. Eighty-five percent of them had previous open surgery. Fifteen patients had adenoma contact with the optic tract. Fourteen patients had a normally functioning hypophysis, 48 patients had complete panhypopituitarism, while the rest retained partial functions of the normal hypophysis. Adenoma volumes ranged between 0.1 and 31.3, the median being 3.45 ccm. The marginal dose ranged between 12 and -35 Gy, with a median of 20 Gy. The follow-up ranged from 36 to 122 months, with a median of 60 months. No adenoma growth was detected; 89 % of treated adenomas decreased in size, with a median volume reduction of 61 %. There was no perimeter vision impairment after radiosurgery, while 4 out of 52 patients with abnormal perimeter vision reported improvement. There was no impairment of oculomotor nerve function. Impairment of hypophysis function was observed in 2 patients. Radiosurgery has a reliable antiproliferative effect on nonsecreting pituitary adenomas. It is a safe treatment with a low risk of morbidity. Short contact between a nonsecreting pituitary adenoma and the optic pathway is not an absolute contraindication for Gamma knife radiosurgery. (author)

Permitting of the accuracy in location of tumours and the accuracy in applying a precise dose covering in stereotactic gamma-knife treatments

International Nuclear Information System (INIS)

Ertl, A. G.

1997-01-01

The gamma-knife is a Co-60 irradiation device, permitting the location of a lesion with an accuracy of millimeters. Moreover, with the Gamma Knife it is possible to apply a precise dose covering the entire area inside the head. In order to visualize a lesion, we mostly have to resort to imaging techniques such as the MR tomography. The accuracy of locating the specific area for the stereotactic treatment was achieved with the help of a special screen plate which we designed ourselves. For determining the precise dose to be applied at the Gamma Knife, the central dose for all four collimator helmets as well as the dose distribution of the combined collimators had to be measured. In case of irradiations in prone position there may be considerable deviations compared to the dose-planning program; this we were able to demonstrate by a TLD array designed by ourselves. A more sophisticated evaluation of new dosimetry techniques - GafChromic films and BANG polymer gel - enabled us to investigate more complex irradiation patterns. (author)

Gamma knife radiosurgery for acoustic neurinomas. Pt. 1. The analysis of tumor control

International Nuclear Information System (INIS)

Fukuoka, Seiji; Seo, Yoshinobu; Nakagawara, Jyoji

1997-01-01

Forty-three patients with the unilateral type of acoustic neurinoma who were treated with gamma knife radiosurgery were analyzed from the viewpoint of tumor control. The follow-up period ranged from 22 to 55 months. The tumors were treated with marginal radiation doses of 9-15 Gy with multiple isocenters. The actuarial tumor reduction rates were 42% at one year, 75% at 2 years, and 92% at 3 years after gamma knife radiosurgery. Transient tumor expansion was seen in 33% of patients, which correlated with previous surgical cases. The present control rate was 91%. SPECT was performed on 15 selected patients before and 1 year and 2 years after gamma knife radiosurgery. 201 TlCl SPECT was used to determine tumor viability, and the early and delayed 99m Tc-DTPA-HSA-D SPECT images were used to assess tumor vascularity and permeability, respectively. The Tl index and HSA-D index of the delayed images were not significantly different from the respective preoperative values. However, there was a statistically significant decrease in the HSA-D index of the early images 1 year after treatment. A statistically significant reduction in tumor volume was seen 2 years after treatment in these 15 patients, meaning that a reduction in tumor vascularity was followed by a reduction in tumor size. One patient underwent surgical excision of the tumor 18 months after gamma knife radiosurgery because the tumor had expanded and resulted in cerebellar ataxia. Histopathologic investigation revealed the presence of some tumor cells with irregularly shaped nuclei and marked intimal thickening or obliteration of the tumor vessels. (K.H.)

Dosimetric characterization of hypofractionated Gamma Knife radiosurgery of large or complex brain tumors versus linear accelerator-based treatments.

Science.gov (United States)

Dong, Peng; Pérez-Andújar, Angélica; Pinnaduwage, Dilini; Braunstein, Steve; Theodosopoulos, Philip; McDermott, Michael; Sneed, Penny; Ma, Lijun

2016-12-01

OBJECTIVE Noninvasive Gamma Knife (GK) platforms, such as the relocatable frame and on-board imaging, have enabled hypofractionated GK radiosurgery of large or complex brain lesions. This study aimed to characterize the dosimetric quality of such treatments against linear accelerator-based delivery systems that include the CyberKnife (CK) and volumetric modulated arc therapy (VMAT). METHODS Ten patients treated with VMAT at the authors' institution for large brain tumors (> 3 cm in maximum diameter) were selected for the study. The median prescription dose was 25 Gy (range 20-30 Gy) in 5 fractions. The median planning target volume (PTV) was 9.57 cm 3 (range 1.94-24.81 cm 3 ). Treatment planning was performed using Eclipse External Beam Planning V11 for VMAT on the Varian TrueBeam system, Multiplan V4.5 for the CyberKnife VSI System, and Leksell GammaPlan V10.2 for the Gamma Knife Perfexion system. The percentage of the PTV receiving at least the prescription dose was normalized to be identical across all platforms for individual cases. The prescription isodose value for the PTV, conformity index, Paddick gradient index, mean and maximum doses for organs at risk, and normal brain dose at variable isodose volumes ranging from the 5-Gy isodose volume (V5) to the 15-Gy isodose volume (V15) were compared for all of the cases. RESULTS The mean Paddick gradient index was 2.6 ± 0.2, 3.2 ± 0.5, and 4.3 ± 1.0 for GK, CK, and VMAT, respectively (p 0.06). The average prescription isodose values were 52% (range 47%-69%), 60% (range 46%-68%), and 88% (range 70%-94%) for GK, CK, and VMAT, respectively, thus producing significant variations in dose hot spots among the 3 platforms. Furthermore, the mean V5 values for GK and CK were similar (p > 0.79) at 71.9 ± 36.2 cm 3 and 73.3 ± 31.8 cm 3 , respectively, both of which were statistically lower (p linear accelerator-based treatments. Such a result supports the use of a large number of isocenters or confocal beams for the

Cavernomas: Outcomes after gamma-knife radiosurgery in Iran

OpenAIRE

Azimi, Parisa; Shahzadi, Sohrab; Bitaraf, Mohammad Ali; Azar, Maziar; Alikhani, Mazdak; Zali, Alireza; Sadeghi, Sohrab

2015-01-01

Background: Treatment of cavernomas remains a challenge in surgically inaccessible regions. The purpose of this study was to evaluate outcomes after gamma-knife surgery (GKS) for these patients. Materials and Methods: A retrospective review of 100 patients treated between 2003 and 2011 was conducted in order to evaluate hemorrhage rates, complications, radiation effects after GKS. Dosage at the tumor margin was stratified into two groups: those that received ?13 Gy; and those who received >13...

SU-E-T-453: Optimization of Dose Gradient for Gamma Knife Radiosurgery.

Science.gov (United States)

Sheth, N; Chen, Y; Yang, J

2012-06-01

The goals of stereotactic radiosurgery (SRS) are the ablation of target tissue and sparing of critical normal tissue. We develop tools to aid in the selection of collimation and prescription (Rx) isodose line to optimize the dose gradient for single isocenter intracranial stereotactic radiosurgery (SRS) with GammaKnife 4C utilizing the updated physics data in GammaPlan v10.1. Single isocenter intracranial SRS plans were created to treat the center of a solid water anthropomorphism head phantom for each GammaKnife collimator (4 mm, 8 mm, 14 mm, and 18 mm). The dose gradient, defined as the difference of effective radii of spheres equal to half and full Rx volumes, and Rx treatment volume was analyzed for isodoses from 99% to 20% of Rx. The dosimetric data on Rx volume and dose gradient vs. Rx isodose for each collimator was compiled into an easy to read nomogram as well as plotted graphically. The 4, 8, 14, and 18 mm collimators have the sharpest dose gradient at the 64%, 70%, 76%, and 77% Rx isodose lines, respectively. This corresponds to treating 4.77 mm, 8.86 mm, 14.78 mm, and 18.77 mm diameter targets with dose gradients radii of 1.06 mm, 1.63 mm, 2.54 mm, and 3.17 mm, respectively. We analyzed the dosimetric data for the most recent version of GammaPlan treatment planning software to develop tools that when applied clinically will aid in the selection of a collimator and Rx isodose line for optimal dose gradient and target coverage for single isocenter intracranial SRS with GammaKnife 4C. © 2012 American Association of Physicists in Medicine.

Verification of gamma knife based fractionated radiosurgery with newly developed head-thorax phantom

International Nuclear Information System (INIS)

Bisht, Raj Kishor; Kale, Shashank Sharad; Natanasabapathi, Gopishankar; Singh, Manmohan Jit; Agarwal, Deepak; Garg, Ajay; Rath, Goura Kishore; Julka, Pramod Kumar; Kumar, Pratik; Thulkar, Sanjay; Sharma, Bhawani Shankar

2016-01-01

Objective: Purpose of the study is to verify the Gamma Knife Extend™ system (ES) based fractionated stereotactic radiosurgery with newly developed head-thorax phantom. Methods: Phantoms are extensively used to measure radiation dose and verify treatment plan in radiotherapy. A human upper body shaped phantom with thorax was designed to simulate fractionated stereotactic radiosurgery using Extend™ system of Gamma Knife. The central component of the phantom aids in performing radiological precision test, dosimetric evaluation and treatment verification. A hollow right circular cylindrical space of diameter 7.0 cm was created at the centre of this component to place various dosimetric devices using suitable adaptors. The phantom is made of poly methyl methacrylate (PMMA), a transparent thermoplastic material. Two sets of disk assemblies were designed to place dosimetric films in (1) horizontal (xy) and (2) vertical (xz) planes. Specific cylindrical adaptors were designed to place thimble ionization chamber inside phantom for point dose recording along xz axis. EBT3 Gafchromic films were used to analyze and map radiation field. The focal precision test was performed using 4 mm collimator shot in phantom to check radiological accuracy of treatment. The phantom head position within the Extend™ frame was estimated using encoded aperture measurement of repositioning check tool (RCT). For treatment verification, the phantom with inserts for film and ion chamber was scanned in reference treatment position using X-ray computed tomography (CT) machine and acquired stereotactic images were transferred into Leksell Gammaplan (LGP). A patient treatment plan with hypo-fractionated regimen was delivered and identical fractions were compared using EBT3 films and in-house MATLAB codes. Results: RCT measurement showed an overall positional accuracy of 0.265 mm (range 0.223 mm–0.343 mm). Gamma index analysis across fractions exhibited close agreement between LGP and film

Clinical experience with Leksell gamma knife in the treatment of trigeminal schwannomas

Institute of Scientific and Technical Information of China (English)

WANG En-min; PAN Li; ZHANG Nan; ZHOU Liang-fu; WANG Bing-jiang; DONG Ya-fei; DAI Jia-zhong; CAI Pei-wu

2005-01-01

@@ Trigeminal nerve schwannomas, which are rare, slowly growing, benign tumors, account for 0.2% to 1.0% of all intracranial tumors and 0.8% to 8.0% of intracranial schwannomas.1-5 These tumors are treated surgically.1-4 The development of microsurgery and skull base surgery has made complete resection possible in most patients. Nevertheless, cranial nerve sequelae appear after complete resection of these tumors because they are located close to the cavernous sinus and usually adhere to the vital vascular and neural structures. As an alternative to microsurgical resection, Leksell gamma knife (LGK) radiosurgery has been performed for patients with intracranial schwannomas to minimize the treatment-related morbidity and achieve a long-term control of tumor growth.6,7 In this report, we describe our 6-year experience in the treatment of 38 patients with trigeminal schwannomas by LGK.

WE-A-304-02: Strategies and Technologies for Cranial Radiosurgery Planning: Gamma Knife

International Nuclear Information System (INIS)

Schlesinger, D.

2015-01-01

The high fractional doses, stringent requirements for accuracy and precision, and surgical perspective characteristic of intracranial radiosurgery create considerations for treatment planning which are distinct from most other radiotherapy procedures. This session will introduce treatment planning techniques specific to two popular intracranial SRS modalities: Gamma Knife and MLC-based Linac. The basic treatment delivery characteristics of each device will be reviewed with a focus on how those characteristics determine the paradigm used for treatment planning. Basic techniques for treatment planning will be discussed, including considerations such as isodose selection, target and organ-at-risk definition, quality indices, and protection of critical structures. Future directions for SRS treatment planning will also be discussed. Learning Objectives: Introduce the basic physical principles of intracranial radiosurgery and how they are realized in the treatment planning paradigms for Gamma Knife and Linac radiosurgery. Demonstrate basic treatment planning techniques. Discuss metrics for evaluating SRS treatment plan quality. Discuss recent and future advances in SRS treatment planning. D. Schlesinger receives research support from Elekta, AB

WE-A-304-02: Strategies and Technologies for Cranial Radiosurgery Planning: Gamma Knife

Energy Technology Data Exchange (ETDEWEB)

Schlesinger, D. [University of Virginia Health Systems (United States)

2015-06-15

The high fractional doses, stringent requirements for accuracy and precision, and surgical perspective characteristic of intracranial radiosurgery create considerations for treatment planning which are distinct from most other radiotherapy procedures. This session will introduce treatment planning techniques specific to two popular intracranial SRS modalities: Gamma Knife and MLC-based Linac. The basic treatment delivery characteristics of each device will be reviewed with a focus on how those characteristics determine the paradigm used for treatment planning. Basic techniques for treatment planning will be discussed, including considerations such as isodose selection, target and organ-at-risk definition, quality indices, and protection of critical structures. Future directions for SRS treatment planning will also be discussed. Learning Objectives: Introduce the basic physical principles of intracranial radiosurgery and how they are realized in the treatment planning paradigms for Gamma Knife and Linac radiosurgery. Demonstrate basic treatment planning techniques. Discuss metrics for evaluating SRS treatment plan quality. Discuss recent and future advances in SRS treatment planning. D. Schlesinger receives research support from Elekta, AB.

The gamma knife: Dose and risk evaluation

International Nuclear Information System (INIS)

Jones, E.D.; Alesso, H.P.; Banks, W.W.; Rathbun, P.A.

1992-01-01

This paper outlines a risk analysis approach designed to identify and assess most likely failure modes and high-risk, human initiated actions for nuclear medical devices. This approach is being developed under the auspices of the US Nuclear Regulatory Commission, Office of Nuclear Material Safety and Safeguards. The methodology is initiated intended to assess risk associated with the use of the Leksell Gamma Unit (LGU) or gamma knife, a gamma stereotactic radiosurgical device

Malignant transformation of clival chordoma after gamma knife surgery. Case report

International Nuclear Information System (INIS)

Tsuboi, Yoshifumi; Hayashi, Nakamasa; Kurimoto, Masanori; Nagai, Shoichi; Sasahara, Masakiyo; Endo, Shunro

2007-01-01

A 54-year-old woman presented a midline clival tumor manifesting as right abducens palsy in May 1997. Magnetic resonance (MR) imaging revealed a midline clival tumor. She underwent surgery twice with the transsphenoidal approach and gamma knife surgery for residual tumor. The histological diagnosis was chordoma. MR imaging revealed that the tumor had extended to the right cerebellopontine angle, with spinal seeding in February 2002. She underwent partial removal of the right cerebellopontine angle tumor. The histological diagnosis was chordoma with slight nuclear atypism. She died 5 years and 5 months after the first gamma knife surgery. Autopsy revealed multiple areas of spinal seeding. Histological examination confirmed malignant transformation with unique epithelial characteristics, possibly caused by gamma knife surgery. (author)

Gamma knife radiosurgery under general anesthesia in childhood

International Nuclear Information System (INIS)

Higuchi, Yoshinori; Serizawa, Toru; Nagano, Osamu

2008-01-01

Gamma knife radiosurgery (GKS) is an important treatment option for pediatric intracranial diseases, such as arteriovenous malformations and brain tumors. To perform GKS in children, general anesthesia is required for placing a stereotactic frame around the head of the patient, who must remain supine for the entire procedure. This report describes the anesthetic management of children who have undergone GKS at our institution. Fifty-one GKS procedures were performed in 43 patients (age range, 2-15 years). Twenty-one patients had arteriovenous malformations, and 14 patients had brain tumors. Twenty-nine patients (67.4%) received general anesthesia. All children 10 years or younger were treated under general anesthesia. General anesthesia for GKS is performed outside of the operating room and involves unique conditions. First, the patients must be transported to multiple sites in the hospital (the neuroangiography suite, the department of radiology for magnetic resonance imaging and computed tomography, and the gamma knife unit). Second, general anesthesia must be maintained in a high magnetic field. Third, medical staff, including anesthesiologists, must remain outside the room during irradiation. Safe and efficient general anesthesia is essential for performing GKS in children. (author)

Histopathological findings after Leksell gamma knife radiosurgery

International Nuclear Information System (INIS)

Langmann, G.; Dexel, A.; Haller-Schober, E.M.; Koelli, H.; Kleinert, R.

2002-01-01

Radiosurgery for uveal melanoma can achieve tumor control according to clinical studies, yet histopathological proof has not been described. 8 eyes after radiosurgery which had to be removed either to regression failure or severe complications like neovascular glaucoma or persisting retinal detachment were investigated histopathologically and compared to 10 uveal melanomas that were treated by enucleation alone. Uveal melanomas treated with the gamma knife showed tumor necrosis (in more than 50 % total necrosis), a higher number of balloon cells, less number of mitoses and vascular changes (thickening of the vessel's walls, obliteration, thrombosis) which could not be demonstrated in enucleated eyes without irradiation. Leksell gamma knife can cause tumor necrosis and varying degrees of cell death and reduced reproducibility. Vascular changes seem to play a major role in tumor regression. (author)

A constrained tracking algorithm to optimize plug patterns in multiple isocenter Gamma Knife radiosurgery planning

International Nuclear Information System (INIS)

Li Kaile; Ma Lijun

2005-01-01

We developed a source blocking optimization algorithm for Gamma Knife radiosurgery, which is based on tracking individual source contributions to arbitrarily shaped target and critical structure volumes. A scalar objective function and a direct search algorithm were used to produce near real-time calculation results. The algorithm allows the user to set and vary the total number of plugs for each shot to limit the total beam-on time. We implemented and tested the algorithm for several multiple-isocenter Gamma Knife cases. It was found that the use of limited number of plugs significantly lowered the integral dose to the critical structures such as an optical chiasm in pituitary adenoma cases. The main effect of the source blocking is the faster dose falloff in the junction area between the target and the critical structure. In summary, we demonstrated a useful source-plugging algorithm for improving complex multi-isocenter Gamma Knife treatment planning cases

Gamma knife simulation using the MCNP4C code and the zubal phantom and comparison with experimental data

International Nuclear Information System (INIS)

Gholami, S.; Kamali Asl, A.; Aghamiri, M.; Allahverdi, M.

2010-01-01

Gamma Knife is an instrument specially designed for treating brain disorders. In Gamma Knife, there are 201 narrow beams of cobalt-60 sources that intersect at an isocenter point to treat brain tumors. The tumor is placed at the isocenter and is treated by the emitted gamma rays. Therefore, there is a high dose at this point and a low dose is delivered to the normal tissue surrounding the tumor. Material and Method: In the current work, the MCNP simulation code was used to simulate the Gamma Knife. The calculated values were compared to the experimental ones and previous works. Dose distribution was compared for different collimators in a water phantom and the Zubal brain-equivalent phantom. The dose profiles were obtained along the x, y and z axes. Result: The evaluation of the developed code was performed using experimental data and we found a good agreement between our simulation and experimental data. Discussion: Our results showed that the skull bone has a high contribution to both scatter and absorbed dose. In other words, inserting the exact material of brain and other organs of the head in digital phantom improves the quality of treatment planning. This work is regarding the measurement of absorbed dose and improving the treatment planning procedure in Gamma-Knife radiosurgery in the brain.

Gamma Knife Simulation Using the MCNP4C Code and the Zubal Phantom and Comparison with Experimental Data

Directory of Open Access Journals (Sweden)

Somayeh Gholami

2010-06-01

Full Text Available Introduction: Gamma Knife is an instrument specially designed for treating brain disorders. In Gamma Knife, there are 201 narrow beams of cobalt-60 sources that intersect at an isocenter point to treat brain tumors. The tumor is placed at the isocenter and is treated by the emitted gamma rays. Therefore, there is a high dose at this point and a low dose is delivered to the normal tissue surrounding the tumor. Material and Method: In the current work, the MCNP simulation code was used to simulate the Gamma Knife. The calculated values were compared to the experimental ones and previous works. Dose distribution was compared for different collimators in a water phantom and the Zubal brain-equivalent phantom. The dose profiles were obtained along the x, y and z axes. Result: The evaluation of the developed code was performed using experimental data and we found a good agreement between our simulation and experimental data. Discussion: Our results showed that the skull bone has a high contribution to both scatter and absorbed dose. In other words, inserting the exact material of brain and other organs of the head in digital phantom improves the quality of treatment planning. This work is regarding the measurement of absorbed dose and improving the treatment planning procedure in Gamma-Knife radiosurgery in the brain.

Risk analysis of Leksell Gamma Knife Model C with automatic positioning system

International Nuclear Information System (INIS)

Goetsch, Steven J.

2002-01-01

Purpose: This study was conducted to evaluate the decrease in risk from misadministration of the new Leksell Gamma Knife Model C with Automatic Positioning System compared with previous models. Methods and Materials: Elekta Instruments, A.B. of Stockholm has introduced a new computer-controlled Leksell Gamma Knife Model C which uses motor-driven trunnions to reposition the patient between isocenters (shots) without human intervention. Previous models required the operators to manually set coordinates from a printed list, permitting opportunities for coordinate transposition, incorrect helmet size, incorrect treatment times, missing shots, or repeated shots. Results: A risk analysis was conducted between craniotomy involving hospital admission and outpatient Gamma Knife radiosurgery. A report of the Institute of Medicine of the National Academies dated November 29, 1999 estimated that medical errors kill between 44,000 and 98,000 people each year in the United States. Another report from the National Nosocomial Infections Surveillance System estimates that 2.1 million nosocomial infections occur annually in the United States in acute care hospitals alone, with 31 million total admissions. Conclusions: All medical procedures have attendant risks of morbidity and possibly mortality. Each patient should be counseled as to the risk of adverse effects as well as the likelihood of good results for alternative treatment strategies. This paper seeks to fill a gap in the existing medical literature, which has a paucity of data involving risk estimates for stereotactic radiosurgery

The results of gamma knife radiosurgery for malignant skull base tumors

Energy Technology Data Exchange (ETDEWEB)

Tanaka, Takayuki; Kobayashi, Tatsuya; Kida, Yoshihisa; Oyama, Hirofumi; Niwa, Masahiro [Komaki City Hospital, Aichi (Japan)

1996-03-01

The results of gamma knife radiosurgery for malignant skull base tumors were analyzed using repeated magnetic resonance imagings and neurological examinations. Nineteen malignant skull base tumors were treated and followed up for 22.3 months (5-40 months) using MR imagings. The mean age was 54.4 years old (ranging from 16-85). Ten were male and 9 were female. Prior to the radiosurgery, removal of the tumors in 17 cases, conventional radiation therapy in 7, and chemotherapy in 4 etc. were performed. The pathological diagnoses were chordoma in 6 patients, metastatic tumors in 5, epipharyngeal carcinoma in 2, adenoid cystic carcinoma in 2, and others in 4. The locations of tumors were clivus in 8, parasellar region in 5, epipharynx in 2, paranasal sinus in 2, C-P angle in 1, and intraorbital region in 1 (14 intracranial and 5 extracranial). The mean diameter of the tumor was 33.5 mm. The mean maximum dose was 26.8 Gy and the mean marginal dose was 12.9 Gy during treatment. Repeated MR imagings revealed decrease of tumor size in 12 cases, showing no change in 1, and increase of tumor size in 5 (unknown in 1). Follow-up neurological examinations showed improvement in 3 patients, no change in 9, and deterioration in 7. There were 11 deaths during a mean follow-up period of 17.8 months (5-32 months) and another 8 cases are alive for a mean follow-up of 30.5 months (20-40 months) after the radiosurgery. Although the tumor size was large at the time of treatment, the results of gamma knife radiosurgery were promising. Considering the quality of life of patients with malignant skull base tumors, it is emphasized that gamma knife treatment is the method of choice compared with radical removal of the tumors. (author).

SU-E-T-542: Comparison of Stereotactic Radiosurgery (SRS) of Brain Lesions Using Gamma Knife, VMAT, IMRT, and Conformal Arcs

International Nuclear Information System (INIS)

Li, S; Charpentier, P; Chan, P; Neicu, T; Miyamoto, C

2014-01-01

Purpose: To compare dose distributions in stereotactic radiation surgery of brain lesions using gamma Knife, VMAT, conformal arcs, and IMRT in order to provide an optimal treatment. Methods: Dose distributions from single shot of 4C model of Gamma Knife at the helmet collimation sizes of 4, 8, 14, and 18 mm in diameter were compared with full arcs with the square shapes of 4×4 (or 5×5), 8×8 (or 10×10), and spherical shapes of 16 or 20 mm in diameter using EDR3 films in the same gamma knife QA phantom. Plans for ten SRS cases with single and multiple lesions were created in gamma knife plans and Pinnacle plans. The external beam plans had enlarged field size by 2-mm and used single conformal full circle arc for solitary lesion and none coplanar arcs/beams for multiple lesions. Coverage, conformity index, dose to critical organs, and integral dose to the brain and nearby critical structures were compared on all plans. Structures and dose matrices were registered in a Velocity deformable image registration system. Results: Single full circle arc from Elekta beam-modulate MLC (4-mm leaf thickness) and agility MLC (5-mm leaf thickness) have larger penumbra and less flatness than that of Gamma Knife single shot. None-coplanar arcs or beams were required to achieve similar dose distribution. In general, Gamma Knife plans provided significant less integral dose than that of linac-based plans. Benefits of IMRT and VMAT versus gamma Knife and conformal arcs were not significant. Conclusion: Our dose measurement and treatment planning evaluation clearly demonstrated dose distribution differences amount current popular SRS modalities for small solitary and multiple brain lesions. The trend of using MLC shape beams or arcs to replace conventional cones should be revisited in order to keep lower integral dose if the late correlates with some radiation-induced side effects. Pilot grant from Elekta LLC

Comparison of penumbra regions produced by ancient Gamma knife model C and Gamma ART 6000 using Monte Carlo MCNP6 simulation.

Science.gov (United States)

Banaee, Nooshin; Asgari, Sepideh; Nedaie, Hassan Ali

2018-07-01

The accuracy of penumbral measurements in radiotherapy is pivotal because dose planning computers require accurate data to adequately modeling the beams, which in turn are used to calculate patient dose distributions. Gamma knife is a non-invasive intracranial technique based on principles of the Leksell stereotactic system for open deep brain surgeries, invented and developed by Professor Lars Leksell. The aim of this study is to compare the penumbra widths of Leksell Gamma Knife model C and Gamma ART 6000. Initially, the structure of both systems were simulated by using Monte Carlo MCNP6 code and after validating the accuracy of simulation, beam profiles of different collimators were plotted. MCNP6 beam profile calculations showed that the penumbra values of Leksell Gamma knife model C and Gamma ART 6000 for 18, 14, 8 and 4 mm collimators are 9.7, 7.9, 4.3, 2.6 and 8.2, 6.9, 3.6, 2.4, respectively. The results of this study showed that since Gamma ART 6000 has larger solid angle in comparison with Gamma Knife model C, it produces better beam profile penumbras than Gamma Knife model C in the direct plane. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multistage stereotactic radiosurgery for large cerebral arteriovenous malformations using the Gamma Knife platform.

Science.gov (United States)

Ding, Chuxiong; Hrycushko, Brian; Whitworth, Louis; Li, Xiang; Nedzi, Lucien; Weprin, Bradley; Abdulrahman, Ramzi; Welch, Babu; Jiang, Steve B; Wardak, Zabi; Timmerman, Robert D

2017-10-01

Radiosurgery is an established technique to treat cerebral arteriovenous malformations (AVMs). Obliteration of larger AVMs (> 10-15 cm 3 or diameter > 3 cm) in a single session is challenging with current radiosurgery platforms due to toxicity. We present a novel technique of multistage stereotactic radiosurgery (SRS) for large intracranial arteriovenous malformations (AVM) using the Gamma Knife system. Eighteen patients with large (> 10-15 cm 3 or diameter > 3 cm) AVMs, which were previously treated using a staged SRS technique on the Cyberknife platform, were retrospectively selected for this study. The AVMs were contoured and divided into 3-8 subtargets to be treated sequentially in a staged approach at half to 4 week intervals. The prescription dose ranged from 15 Gy to 20 Gy, depending on the subtarget number, volume, and location. Gamma Knife plans using multiple collimator settings were generated and optimized. The coordinates of each shot from the initial plan covering the total AVM target were extracted based on their relative positions within the frame system. The shots were regrouped based on their location with respect to the subtarget contours to generate subplans for each stage. The delivery time of each shot for a subtarget was decay corrected with 60 Co for staging the treatment course to generate the same dose distribution as that planned for the total AVM target. Conformality indices and dose-volume analysis were performed to evaluate treatment plans. With the shot redistribution technique, the composite dose for the multistaged treatment of multiple subtargets is equivalent to the initial plan for total AVM target. Gamma Knife plans resulted in an average PTV coverage of 96.3 ± 0.9% and a PITV of 1.23 ± 0.1. The resulting Conformality indices, V 12Gy and R 50 dose spillage values were 0.76 ± 0.05, 3.4 ± 1.8, and 3.1 ± 0.5 respectively. The Gamma Knife system can deliver a multistaged conformal dose to treat large AVMs when correcting for

The change of p16 gene expression in glioma cell line C6 after radiation with gamma knife

International Nuclear Information System (INIS)

Zhao Xingli; Zhao Conghai; Tian Yu

2002-01-01

Objective: T observe the change of expression of p16 gene product, P16 protein, after treated by gamma knife on glioma cell line C6. Methods: Glioma C6 cells proliferated in vitro, treated by γ-knife in dose of 5.00 and 6.22 Gy, respectively. P16 protein was detected by immunohistochemical technique and image analysis. Results: The P16 protein in glioma C6 cells was notably increased after treatment with γ knife (P < 0.01). The grey number in C6 group (control group) was 167.1 +- 6.2 and was 155.4 +- 2.0 and 124.9 +- 7.1, respectively, in 5.00 Gy and 6.22 Gy gamma knife treated group. Conclusion: It is suggests that one of the mechanisms of glioma cell C6 apoptosis induced by γ-knife radiation may be associated with activation of p16 gene and increase of P16 protein expression

Comparison of gamma knife validation film's analysis results of different film dose analysis software

International Nuclear Information System (INIS)

Cheng Xiaojun; Zhang Conghua; Liu Han; Dai Fuyou; Hu Chuanpeng; Liu Cheng; Yao Zhongfu

2011-01-01

Objective: To compare the analytical result of different kinds of film dose analysis software for the same gamma knife, analyze the reasons of difference caused, and explore the measurements and means for quality control and quality assurance during testing gamma knife and analyzing its result. Methods: To test the Moon Deity gamma knife with Kodak EDR2 film and γ-Star gamma knife with GAFCHROMIC® EBT film, respectively. All the validation films are scanned to proper imagine format for dose analysis software by EPSON PERFECTION V750 PRO scanner. Then imagines of Moon Deity gamma knife are analyzed with Robot Knife Adjuvant 1.09 and Fas-09 1.0, and imagines of γ-Star gamma knife with Fas-09 and MATLAB 7.0. Results: There is no significant difference in the maximum deviation of radiation field size (Full Width at Half Maximum, FWHM) and its nominal value between Robot Knife Adjuvant and Fas-09 for Moon Deity gamma knife (t=-2.133, P>0.05). The analysis on the radiation field's penumbra region width of collimators which have different sizes indicated that the differences are significant (t=-8.154, P<0.05). There is no significant difference in the maximum deviation of FWHM and its nominal value between Fas-09 and MATLAB for γ-Star gamma knife (t=-1.384, P>0.05). However, following national standards,analysis of φ4 mm width of collimators can obtain different results according to the two kinds software, and the result of Fas-09 is not qualified while MATLAB is qualified. The analysis on the radiation field's penumbra region width of collimators which have different sizes indicates that the differences are significant (t=3.074, P<0.05). The imagines are processed with Fas-09. The analysis of imagine in the pre-and the post-processing indicates that there is no significant difference in the maximum deviation of FWHM and its nominal value (t=0.647, P>0.05), and the analytical result of the radiation field's penumbra region width indicates that there is

Dose conformity of gamma knife radiosurgery and risk factors for complications

International Nuclear Information System (INIS)

Nakamura, Jean L.; Verhey, Lynn J.; Smith, Vernon; Petti, Paula L.; Lamborn, Kathleen R.; Larson, David A.; Wara, William M.; McDermott, Michael W.; Sneed, Penny K.

2001-01-01

Purpose: To quantitatively evaluate dose conformity achieved using Gamma Knife radiosurgery, compare results with those reported in the literature, and evaluate risk factors for complications. Methods and Materials: All lesions treated at our institution with Gamma Knife radiosurgery from May 1993 (when volume criteria were routinely recorded) through December 1998 were reviewed. Lesions were excluded from analysis for reasons listed below. Conformity index (the ratio of prescription volume to target volume) was calculated for all evaluable lesions and for lesions comparable to those reported in the literature on conformity of linac radiosurgery. Univariate Cox regression models were used to test for associations between treatment parameters and toxicity. Results: Of 1612 targets treated in 874 patients, 274 were excluded, most commonly for unavailability of individual prescription volume data because two or more lesions were included within the same dose matrix (176 lesions), intentional partial coverage for staged treatment of large arteriovenous malformations (AVMs) (33 lesions), and missing target volume data (26 lesions). The median conformity indices were 1.67 for all 1338 evaluable lesions and 1.40-1.43 for lesions comparable to two linac radiosurgery series that reported conformity indices of 1.8 and 2.7, respectively. Among all 651 patients evaluable for complications, there were one Grade 5, eight Grade 4, and 27 Grade 3 complications. Increased risk of toxicity was associated with larger target volume, maximum lesion diameter, prescription volume, or volume of nontarget tissue within the prescription volume. Conclusions: Gamma Knife radiosurgery achieves much more conformal dose distributions than those reported for conventional linac radiosurgery and somewhat more conformal dose distributions than sophisticated linac radiosurgery techniques. Larger target, nontarget, or prescription volumes are associated with increased risk of toxicity

Spectroscopic Study of Radiation around the Leksell Gamma Knife for Room Shielding Applications

OpenAIRE

Hubert, Alexis

2017-01-01

Any center planning to install a Gamma Knife radiosurgery unit has to provide for an efficient shielding of the treatment room, to protect the patient, the staff and the public, against undesired radiation. The shielding barrier design is controlled by national and international recommendations; the reference documents for gamma ray radiotherapy facilities are the National Council on Radiation Protection and Measurements (NCRP) reports 49 and 151. However, some facts highlighted in this thesi...

A fully automatic approach for multimodal PET and MR image segmentation in gamma knife treatment planning.

Science.gov (United States)

Rundo, Leonardo; Stefano, Alessandro; Militello, Carmelo; Russo, Giorgio; Sabini, Maria Gabriella; D'Arrigo, Corrado; Marletta, Francesco; Ippolito, Massimo; Mauri, Giancarlo; Vitabile, Salvatore; Gilardi, Maria Carla

2017-06-01

Nowadays, clinical practice in Gamma Knife treatments is generally based on MRI anatomical information alone. However, the joint use of MRI and PET images can be useful for considering both anatomical and metabolic information about the lesion to be treated. In this paper we present a co-segmentation method to integrate the segmented Biological Target Volume (BTV), using [ 11 C]-Methionine-PET (MET-PET) images, and the segmented Gross Target Volume (GTV), on the respective co-registered MR images. The resulting volume gives enhanced brain tumor information to be used in stereotactic neuro-radiosurgery treatment planning. GTV often does not match entirely with BTV, which provides metabolic information about brain lesions. For this reason, PET imaging is valuable and it could be used to provide complementary information useful for treatment planning. In this way, BTV can be used to modify GTV, enhancing Clinical Target Volume (CTV) delineation. A novel fully automatic multimodal PET/MRI segmentation method for Leksell Gamma Knife ® treatments is proposed. This approach improves and combines two computer-assisted and operator-independent single modality methods, previously developed and validated, to segment BTV and GTV from PET and MR images, respectively. In addition, the GTV is utilized to combine the superior contrast of PET images with the higher spatial resolution of MRI, obtaining a new BTV, called BTV MRI . A total of 19 brain metastatic tumors, undergone stereotactic neuro-radiosurgery, were retrospectively analyzed. A framework for the evaluation of multimodal PET/MRI segmentation is also presented. Overlap-based and spatial distance-based metrics were considered to quantify similarity concerning PET and MRI segmentation approaches. Statistics was also included to measure correlation among the different segmentation processes. Since it is not possible to define a gold-standard CTV according to both MRI and PET images without treatment response assessment

Successful use of Gamma Knife surgery in a distal lenticulostriate artery aneurysm intervention.

Science.gov (United States)

Lan, ZhiGang; Li, Jin; You, Chao; Chen, Jing

2012-02-01

We report a case of a 21-year-old woman who underwent radiosurgical treatment of a distal lenticulostriate artery (LSA) aneurysm. Twenty-two months after treatment, repeat angiography demonstrated patency of the parent vessel and complete obliteration of the aneurysm. Our case implies that Gamma Knife surgery (GKS) might serve as an alternative microinvasive technique in the treatment of LSA aneurysms, making this procedure a potential addition to present methods.

Angiomatous lesion and delayed cyst formation after gamma knife surgery for intracranial meningioma: case report and review of literatures.

Science.gov (United States)

Liu, Zhiyong; He, Min; Chen, Hongxu; Liu, Yi; Li, Qiang; Li, Lin; Li, Jin; Chen, Haifeng; Xu, Jianguo

2015-01-01

Gamma Knife has become a major therapeutic method for intracranial meningiomas, vascular malformations and schwannomas with exact effect. In recent years an increasing number of delayed complications after Gamma Knife surgery have been reported, such as secondary tumors, cystic changes or cyst formation. But angiomatous lesion and delayed cyst formation after Gamma Knife for intracranial lesion has rarely been reported. Here we report the first case of angiomatous lesion and delayed cyst formation following Gamma Knife for intracranial meningioma and discuss its pathogenesis.

Adaptive fractionated stereotactic Gamma Knife radiotherapy of meningioma using integrated stereotactic cone-beam-CT and adaptive re-planning (a-gkFSRT)

Energy Technology Data Exchange (ETDEWEB)

Stieler, F.; Wenz, F.; Abo-Madyan, Y.; Schweizer, B.; Polednik, M.; Herskind, C.; Giordano, F.A.; Mai, S. [University of Heidelberg, Department of Radiation Oncology, University Medical Center Mannheim, Mannheim (Germany)

2016-11-15

The Gamma Knife Icon (Elekta AB, Stockholm, Sweden) allows frameless stereotactic treatment using a combination of cone beam computer tomography (CBCT), a thermoplastic mask system, and an infrared-based high-definition motion management (HDMM) camera system for patient tracking during treatment. We report on the first patient with meningioma at the left petrous bone treated with adaptive fractionated stereotactic radiotherapy (a-gkFSRT). The first patient treated with Gamma Knife Icon at our institute received MR imaging for preplanning before treatment. For each treatment fraction, a daily CBCT was performed to verify the actual scull/tumor position. The system automatically adapted the planned shot positions to the daily position and recalculated the dose distribution (online adaptive planning). During treatment, the HDMM system recorded the intrafractional patient motion. Furthermore, the required times were recorded to define a clinical treatment slot. Total treatment time was around 20 min. Patient positioning needed 0.8 min, CBCT positioning plus acquisition 1.65 min, CT data processing and adaptive planning 2.66 min, and treatment 15.6 min. The differences for the five daily CBCTs compared to the reference are for rotation: -0.59 ± 0.49 /0.18 ± 0.20 /0.05 ± 0.36 and for translation: 0.94 ± 0.52 mm/-0.08 ± 0.08 mm/-1.13 ± 0.89 mm. Over all fractions, an intrafractional movement of 0.13 ± 0.04 mm was observed. The Gamma Knife Icon allows combining the accuracy of the stereotactic Gamma Knife system with the flexibility of fractionated treatment with the mask system and CBCT. Furthermore, the Icon system introduces a new online patient tracking system to the clinical routine. The interfractional accuracy of patient positioning was controlled with a thermoplastic mask and CBCT. (orig.) [German] Das Gamma Knife Icon (Elekta AB, Stockholm, Schweden) ermoeglicht die stereotaktische Behandlung von Patienten mittels Cone-beam-Computertomographie (CBCT

A case of obstructive hydrocephalus by aqueduct stenosis following gamma knife surgery for arteriovenous malformation around the pineal body

International Nuclear Information System (INIS)

Funakoshi, Yusuke; Natori, Yoshihiro; Imamoto, Naoyuki; Inoue, Daisuke; Mori, Megumu; Yamada, Tetsuhisa

2017-01-01

Stereotactic radiosurgery, including gamma knife surgery, has been widely performed as minimally invasive treatment for arteriovenous malformation (AVM). While its safety and efficacy have been well reported, some problems also have been reported. Patients who undergo radiosurgery must wait for a few years from the time of treatment and remain exposed to the risk of bleeding until obliteration of the AVM is confirmed, and technical limitations may lead to incomplete administration of the intended treatment. In addition, severe complications are occasionally reported. Here, we present a case of obstructive hydrocephalus caused by aqueductal stenosis in a 63-year-old man who underwent gamma knife surgery for AVM around the pineal body 8 years previously. On visiting our department, he presented with mild disturbance of gait and consciousness. Other physical and neurological examinations were unremarkable. CT demonstrated dilatation of the lateral ventricles and the third ventricle. Because the aqueduct of the midbrain and fourth ventricle were not dilated, obstructive hydrocephalus due to localized aqueductal stenosis was suspected. Endoscopic neurosurgery was performed and stenosis in the aqueduct of the midbrain caused by a membrane-like structure was confirmed. Aqueductal stenosis occurred as a result of inflammation following gamma knife surgery, which extended to the cicatricial tissue and eventually caused a stenosed aqueduct of the midbrain. After the endoscopic third ventriculostomy, the hydrocephalus improved and no recurrence has appeared since. To the best of our knowledge, there have been no previous reports of obstructive hydrocephalus attributable to aqueductal stenosis caused by inflammation following gamma knife surgery. (author)

SU-E-T-563: Multi-Fraction Stereotactic Radiosurgery with Extend System of Gamma Knife: Treatment Verification Using Indigenously Designed Patient Simulating Multipurpose Phantom

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Bisht, R; Kale, S; Gopishankar, N; Rath, G; Julka, P; Agarwal, D; Singh, M; Garg, A; Kumar, P; Thulkar, S; Sharma, B [All India Institute of Medical Sciences, New Delhi (India)

2015-06-15

Purpose: Aim of the study is to evaluate mechanical and radiological accuracy of multi-fraction regimen and validate Gamma knife based fractionation using newly developed patient simulating multipurpose phantom. Methods: A patient simulating phantom was designed to verify fractionated treatments with extend system (ES) of Gamma Knife however it could be used to validate other radiotherapy procedures as well. The phantom has options to insert various density material plugs and mini CT/MR distortion phantoms to analyze the quality of stereotactic imaging. An additional thorax part designed to predict surface doses at various organ sites. The phantom was positioned using vacuum head cushion and patient control unit for imaging and treatment. The repositioning check tool (RCT) was used to predict phantom positioning under ES assembly. The phantom with special inserts for film in axial, coronal and sagittal plane were scanned with X-Ray CT and the acquired images were transferred to treatment planning system (LGP 10.1). The focal precession test was performed with 4mm collimator and an experimental plan of four 16mm collimator shots was prepared for treatment verification of multi-fraction regimen. The prescription dose of 5Gy per fraction was delivered in four fractions. Each fraction was analyzed using EBT3 films scanned with EPSON 10000XL Scanner. Results: The measurement of 38 RCT points showed an overall positional accuracy of 0.28mm. The mean deviation of 0.28% and 0.31 % were calculated as CT and MR image distortion respectively. The radiological focus accuracy test showed its deviation from mechanical center point of 0.22mm. The profile measurement showed close agreement between TPS planned and film measured dose. At tolerance criteria of 1%/1mm gamma index analysis showed a pass rate of > 95%. Conclusion: Our results show that the newly developed multipurpose patient simulating phantom is highly suitable for the verification of fractionated stereotactic

Long-term effectiveness and safety of stereotactic gamma knife surgery as a primary sole treatment in the management of glomus jagulare tumor.

Science.gov (United States)

Hafez, Raef F A; Morgan, Magad S; Fahmy, Osama M; Hassan, Hamdy T

2018-05-01

This study aims to report and confirm long-term effectiveness and safety of stereotactic Gamma Knife Surgery as a primary sole treatment in the management of 40 glomus jagulare tumors patients. Retrospective analysis of clinical and radiological outcomes of 40 GJTs consecutive patients treated with GKS as primary sole treatment at International Medical Center (IMC), Cairo-Egypt from the beginning of 2005 till the end of 2014,with mean follow-up period of 84 months (range 36-156 months), mean tumor volume was 6.5 cc, and mean peripheral radiation dose of 15 Gy, to mean isodose curve of 38%. The most common neurological deficit at initial evaluation was bulbar symptoms in 24 patients, followed by pulsatile tinnitus in 22, deterioration of hearing in 20 patients. The overall clinical control achieved in 92.5% of patients, while actuarial tumor size control rate post- GKS was 97.5% at 3 years, 97% at 5 years and 92% at 10 years of follow-up period. Gamma knife surgery could be used effectively and safely as a primary sole treatment tool in the management of glomus jugulare tumors. Copyright © 2018 Elsevier B.V. All rights reserved.

A cerebral arteriovenous malformation grading system for gamma knife radiosurgery with the aim of early obliteration

International Nuclear Information System (INIS)

Negishi, Masatoshi; Inoue, Hiroshi K.; Hirato, Masafumi; Yokoe, Takao; Iino, Yuichi; Ohye, Chihiro; Shibazaki, Tohru

1998-01-01

Bleeding in the latency period before obliteration considerably worsens the prognosis of cerebral arteriovenous malformations (AVMs). Bleeding risk should be considered and total obliteration should performed as early as possible. In this study we investigated factors related to early obliteration following Gamma Knife radiosurgery and proposed a grading system for AVMs. Forty-six patients with cerebral AVMs followed angiographically within twelve months after Gamma Knife radiosurgery were analyzed. Four factors, volume, type (categorized by our own method), location, and marginal dose were found to be correlated with early obliteration rate. We scored these factors, and categorized the scores into a grade O to 6 Gamma Knife Score (GKS), and evaluated the obliteration rate of each grade. The total obliteration rate in twelve months according to grade was: grades 0 and 1, 61.9%; grades 2 and 3, 36.0%, grades 4 and 5, 16.7%. AVMs with a low GKS (grades 0 and 1) had a high early obliteration rate and seemed suitable for Gamma Knife radiosurgery. Since early obliteration is difficult to obtain in the high grade group, endovascular surgery should be considered to reduce the GKS before Gamma Knife radiosurgery. (author)

Volumetric changes and clinical outcome for petroclival meningiomas after primary treatment with Gamma Knife radiosurgery.

Science.gov (United States)

Sadik, Zjiwar H A; Lie, Suan Te; Leenstra, Sieger; Hanssens, Patrick E J

2018-01-26

OBJECTIVE Petroclival meningiomas (PCMs) can cause devastating clinical symptoms due to mass effect on cranial nerves (CNs); thus, patients harboring these tumors need treatment. Many neurosurgeons advocate for microsurgery because removal of the tumor can provide relief or result in symptom disappearance. Gamma Knife radiosurgery (GKRS) is often an alternative for surgery because it can cause tumor shrinkage with improvement of symptoms. This study evaluates qualitative volumetric changes of PCM after primary GKRS and its impact on clinical symptoms. METHODS The authors performed a retrospective study of patients with PCM who underwent primary GKRS between 2003 and 2015 at the Gamma Knife Center of the Elisabeth-Tweesteden Hospital in Tilburg, the Netherlands. This study yields 53 patients. In this study the authors concentrate on qualitative volumetric tumor changes, local tumor control rate, and the effect of the treatment on trigeminal neuralgia (TN). RESULTS Local tumor control was 98% at 5 years and 93% at 7 years (Kaplan-Meier estimates). More than 90% of the tumors showed regression in volume during the first 5 years. The mean volumetric tumor decrease was 21.2%, 27.1%, and 31% at 1, 3, and 6 years of follow-up, respectively. Improvement in TN was achieved in 61%, 67%, and 70% of the cases at 1, 2, and 3 years of follow-up, respectively. This was associated with a mean volumetric tumor decrease of 25% at the 1-year follow-up to 32% at the 3-year follow-up. CONCLUSIONS GKRS for PCMs yields a high tumor control rate with a low incidence of neurological deficits. Many patients with TN due to PCM experienced improvement in TN after radiosurgery. GKRS achieves significant volumetric tumor decrease in the first years of follow-up and thereafter.

Adaptive fractionated stereotactic Gamma Knife radiotherapy of meningioma using integrated stereotactic cone-beam-CT and adaptive re-planning (a-gkFSRT)

International Nuclear Information System (INIS)

Stieler, F.; Wenz, F.; Abo-Madyan, Y.; Schweizer, B.; Polednik, M.; Herskind, C.; Giordano, F.A.; Mai, S.

2016-01-01

The Gamma Knife Icon (Elekta AB, Stockholm, Sweden) allows frameless stereotactic treatment using a combination of cone beam computer tomography (CBCT), a thermoplastic mask system, and an infrared-based high-definition motion management (HDMM) camera system for patient tracking during treatment. We report on the first patient with meningioma at the left petrous bone treated with adaptive fractionated stereotactic radiotherapy (a-gkFSRT). The first patient treated with Gamma Knife Icon at our institute received MR imaging for preplanning before treatment. For each treatment fraction, a daily CBCT was performed to verify the actual scull/tumor position. The system automatically adapted the planned shot positions to the daily position and recalculated the dose distribution (online adaptive planning). During treatment, the HDMM system recorded the intrafractional patient motion. Furthermore, the required times were recorded to define a clinical treatment slot. Total treatment time was around 20 min. Patient positioning needed 0.8 min, CBCT positioning plus acquisition 1.65 min, CT data processing and adaptive planning 2.66 min, and treatment 15.6 min. The differences for the five daily CBCTs compared to the reference are for rotation: -0.59 ± 0.49 /0.18 ± 0.20 /0.05 ± 0.36 and for translation: 0.94 ± 0.52 mm/-0.08 ± 0.08 mm/-1.13 ± 0.89 mm. Over all fractions, an intrafractional movement of 0.13 ± 0.04 mm was observed. The Gamma Knife Icon allows combining the accuracy of the stereotactic Gamma Knife system with the flexibility of fractionated treatment with the mask system and CBCT. Furthermore, the Icon system introduces a new online patient tracking system to the clinical routine. The interfractional accuracy of patient positioning was controlled with a thermoplastic mask and CBCT. (orig.) [de

Gamma Knife radiosurgery for glomus jugulare tumors: a single-center series of 75 cases.

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Ibrahim, Ramez; Ammori, Mohannad B; Yianni, John; Grainger, Alison; Rowe, Jeremy; Radatz, Matthias

2017-05-01

OBJECTIVE Glomus jugulare tumors are rare indolent tumors that frequently involve the lower cranial nerves (CNs). Complete resection can be difficult and associated with lower CN injury. Gamma Knife radiosurgery (GKRS) has established its role as a noninvasive alternative treatment option for these often formidable lesions. The authors aimed to review their experience at the National Centre for Stereotactic Radiosurgery, Sheffield, United Kingdom, specifically the long-term tumor control rate and complications of GKRS for these lesions. METHODS Clinical and radiological data were retrospectively reviewed for patients treated between March 1994 and December 2010. Data were available for 75 patients harboring 76 tumors. The tumors in 3 patients were treated in 2 stages. Familial and/or hereditary history was noted in 12 patients, 2 of whom had catecholamine-secreting and/or active tumors. Gamma Knife radiosurgery was the primary treatment modality in 47 patients (63%). The median age at the time of treatment was 55 years. The median tumor volume was 7 cm 3 , and the median radiosurgical dose to the tumor margin was 18 Gy (range 12-25 Gy). The median duration of radiological follow-up was 51.5 months (range 12-230 months), and the median clinical follow-up was 38.5 months (range 6-223 months). RESULTS The overall tumor control rate was 93.4% with low CN morbidity. Improvement of preexisting deficits was noted in 15 patients (20%). A stationary clinical course and no progression of symptoms were noted in 48 patients (64%). Twelve patients (16%) had new symptoms or progression of their preexisting symptoms. The Kaplan-Meier actuarial tumor control rate was 92.2% at 5 years and 86.3% at 10 years. CONCLUSIONS Gamma Knife radiosurgery offers a risk-versus-benefit treatment option with very low CN morbidity and stable long-term results.

The usefulness of adjuvant therapy using gamma knife radiosurgery for the recurrent or residual nonfunctioning pituitary adenomas

International Nuclear Information System (INIS)

Iwai, Yoshiyasu; Yamanaka, Kazuhiro; Yoshioka, Katsunobu; Yoshimura, Masaki; Honda, Yuji; Matsusaka, Yasuhiro; Komiyama, Masaki; Yasui, Toshihiro

2005-01-01

We evaluated the treatment results of nonfunctioning pituitary adenomas in the era of radiosurgery. Between January 1994 and December 2003, we operated on 44 patients with nonfunctioning pituitary adenomas. Forty-three patients were operated on by transsphenoidal surgery and one patient was operated on by the transcranial approach. Total removal was able to be achieved in 13 patients (30%). Gamma knife radiosurgery was performed for residual tumor in 26 patients and for recurrence in 2 patients. The mean tumor diameter at the gamma knife radiosurgery was 18.2 mm (7.9 to 26.3 mm). The treatment dose was a mean of 12.3 Gy (8 to 16 Gy) to the tumor margin. The mean follow-up period after radiosurgery was 36.4 months. Tumor growth control was able to be achieved in 26 patients (93%). Two patients (7%) required adrenal and thyroid hormonal replacement during the follow-up period after radiosurgery due to radiation-induced endocrinopathy. None of the patients suffered from new cranial nerve deficits. This included optic neuropathy. Surgical resection using transsphenoidal surgery and subsequent gamma knife radiosurgery for residual and recurrent tumor proved to have a highly effective tumor growth control rate, and maintained the quality of life in patients with nonfunctioning pituitary adenomas. (author)

Gamma knife radiosurgery for arteriovenous malformation in children

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Tanaka, Takayuki; Kobayashi, Tatsuya [Komaki City Hospital, Aichi (Japan)

1995-04-01

Intracranial arteriovenous malformations (AVM) of 38 children were treated by gamma knife radiosurgery. Their clinical courses and the effect of the treatment in 19 patients who had angiographies are described. There were 21 boys and 17 girls with a mean age of 11.2 years. The initial signs and symptoms were: intracranial hemorrhage in 32, seizures in 4, and headache in 2. Prior to the radiosurgery, craniotomy was performed in 10 patients, ventricular drainage, in 8, ventriculoperitoneal shunting in 4, and intravascular embolization in 3. The AVM was in the parietal lobe in 8 patients, in the thalamus in 7, in the occipital lobe in 5, in the temporal lobe in 4, in the basal ganglia in 4, in the corpus callosum in 3, and in other locations in 8. The mean diameter of the nidus was 18.9 mm. According to Spetzler`s classification of AVM, 23 (60.5%) were grade III, 10 were grade II, 3 were grade IV, and 2 were grade VI. The mean maximum dose was 36.3 Gy, and the mean peripheral dose was 20.2 Gy. Follow-up angiography was done in 19 patients during a mean follow-up period of 14.9 months. Complete occlusion of the nidus was obtained within 1 year in 10 of 15 patients (67%). All 6 patients who underwent angiography 2 years after treatment showed complete obliteration of the AVM. Only 1 patient developed hemiparesis due to radiation necrosis. It is considered that occlusion of AVMs by gamma knife radiosurgery is probably more effective and safer in children than in adults. (author).

Long-term quality of life and tumour control following gamma knife radiosurgery for vestibular schwannoma

DEFF Research Database (Denmark)

Wangerid, Theresa; Bartek, Jiri; Svensson, Mikael

2014-01-01

Gamma knife radiosurgery (GKRS) has for the last decades been an established treatment option for patients with small- or medium-sized vestibular schwannomas (VS), although little data is reported on long-term outcome regarding quality of life (QOL) and tumour control in this patient category...

Arteriovenous malformations of the brain treated with gamma knife; Early effects in 25 children

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Tanaka, Takayuki; Kobayashi, Tatsuya; Kida, Yoshihisa (Komaki City Hospital, Hokkaido (Japan))

1994-02-01

The early effects of treatment with gamma knife radiosurgery for intracranial arteriovenous malformations (AVM) were investigated in 25 children, 15 boys and 10 girls, aged 2 to 15 years (mean 11). Neurological signs were hemiparesis in 10, mental retardation in 2, etc. Initial events were hemorrhage in 23 (92%) and epilepsy in 2 patients. The locations of AVM were parietal lobe in 6, thalamus in 4 patients, etc. The mean diameter of the nidus was 1.97 cm, and the volume was under 10 cm[sup 3] in 21 cases. Of the 25 patients were classified as Grade II or higher by the Spetzler and Martin grading system. The mean maximum dose was 36.2 Gy, and marginal dose of 20.2 Gy with a mean isocenter of 3.2 were used. Follow-up angiography was performed more than one year after treatment in 7 patients. Five of the 7 (71.4%) showed complete obliteration of the AVM. No patients has had rebleeding after treatment so far, but one patient has had hemiparesis due to radiation-induced edema. Stereotactic radiosurgery by gamma knife is a preventive treatment of intracranial AVM in childhood. (author).

[Alterations of glial fibrillary acidic protein in rat brain after gamma knife irradiation].

Science.gov (United States)

Ma, Z M; Jiang, B; Ma, J R

2001-08-28

To study glial fibrillary acidic protein (GFAP) immunoreactivity in different time and water content of the rat brain treated with gamma knife radiotherapy and to understand the alteration course of the brain lesion after a single high dose radiosurgical treatment. In the brains of the normal rats were irradiated by gamma knife with 160 Gy-high dose. The irradiated rats were then killed on the 1st day, 7th day, 14th day, and 28th day after radiotherapy, respectively. The positive cells of GFAP in brain tissue were detected by immunostaining; the water content of the brain tissue was measured by microgravimetry. The histological study of the irradiated brain tissue was performed with H.E. and examined under light microscope. The numbers of GFAP-positive astrocytes began to increase on the 1st day after gamma knife irradiation. It was enlarged markedly in the number and size of GFAP-stained astrocytes over the irradiated areas. Up to the 28th day, circumscribed necrosis foci (4 mm in diameter) was seen in the central area of the target. In the brain tissue around the necrosis, GFAP-positive astrocytes significantly increased (P gravity in the irradiated brain tissue the 14th and 28th day after irradiation. The results suggest that GFAP can be used as a marker for the radiation-induced brain injury. The brain edema and disruption of brain-blood barrier can be occurred during the acute stage after irradiation.

MRI textures as outcome predictor for Gamma Knife radiosurgery on vestibular schwannoma

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Langenhuizen, P. P. J. H.; Legters, M. J. W.; Zinger, S.; Verheul, H. B.; Leenstra, S.; de With, P. H. N.

2018-02-01

Vestibular schwannomas (VS) are benign brain tumors that can be treated with high-precision focused radiation with the Gamma Knife in order to stop tumor growth. Outcome prediction of Gamma Knife radiosurgery (GKRS) treatment can help in determining whether GKRS will be effective on an individual patient basis. However, at present, prognostic factors of tumor control after GKRS for VS are largely unknown, and only clinical factors, such as size of the tumor at treatment and pre-treatment growth rate of the tumor, have been considered thus far. This research aims at outcome prediction of GKRS by means of quantitative texture feature analysis on conventional MRI scans. We compute first-order statistics and features based on gray-level co- occurrence (GLCM) and run-length matrices (RLM), and employ support vector machines and decision trees for classification. In a clinical dataset, consisting of 20 tumors showing treatment failure and 20 tumors exhibiting treatment success, we have discovered that the second-order statistical metrics distilled from GLCM and RLM are suitable for describing texture, but are slightly outperformed by simple first-order statistics, like mean, standard deviation and median. The obtained prediction accuracy is about 85%, but a final choice of the best feature can only be made after performing more extensive analyses on larger datasets. In any case, this work provides suitable texture measures for successful prediction of GKRS treatment outcome for VS.

A quality assurance program in stereotactic radiosurgery using the gamma knife unit

International Nuclear Information System (INIS)

Stuecklschweiger, G.F.; Feichtinger, K.

1998-01-01

Because of the large single fraction dose in stereotactic radiosurgery it is important to guarantee a high geometric and dosimetric accuracy. The paper represent the quality assurance program for the Gamma Knife unit at the University Clinic of Neurosurgery in Graz. The program includes the following procedures: Timer control, mechanical radiation isocenter coincidence, trunnion centricity, helmet microswitches test, radiation output and relative helmet factors, dose profile verification, safety interlocks checks and software quality assurance. In summary, the mechanical accuracy and reproducibility of the Gamma Knife unit are [de

A simulation study on the dose distribution for a single beam of the gamma knife

International Nuclear Information System (INIS)

Chen, Chin-cheng; Jiang, Shiang-Huei; Lee, Chung-chi; Shiau, Cheng-Ying

2000-01-01

The purpose of this study is to evaluate the impact of the tissue heterogeneity on the dose distribution for a single beam of the gamma knife. The EGS4 Monte Carlo code was used to simulate both depth and radial profiles of the radiation dose in homogeneous and heterogeneous phantoms, respectively. The results are compared with the dose distribution calculated using the mathematical model of Gamma Plan, the treatment planning system of the gamma knife. The skull and sinus heterogeneity were simulated by a Teflon shell and an air shell, respectively. It was found that the tissue heterogeneity caused significant perturbation on the absolute depth dose at the focus as well as on the depth-dose distribution near the phantom surface and/or at the interface but little effect on the radial dose distribution. The effect of the beam aperture on the depth-dose distribution was also investigated in this study. (author)

Safety and efficacy of endovascular therapy and gamma knife surgery for brain arteriovenous malformations in China: Study protocol for an observational clinical trial

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Hengwei Jin

2017-09-01

Full Text Available Introduction: Brain arteriovenous malformations (BAVMs are associated with high morbidity and mortality. The treatment of BAVM remains controversial. Microinvasive treatment, including endovascular therapy and gamma knife surgery, has been the first choice in many conditions. However, the overall clinical outcome of microinvasive treatment remains unknown and a prospective trial is needed. Methods: This is a prospective, non-randomized, and multicenter observational registry clinical trial to evaluate the safety and efficacy of microinvasive treatment for BAVMs. The study will require up to 400 patients in approximately 12 or more centers in China, followed for 2 years. Main subjects of this study are BAVM patients underwent endovascular therapy and/or gamma knife surgery. The trial will not affect the choice of treatment modality. The primary outcomes are perioperative complications (safety, and postoperative hemorrhage incidence rate and complete occlusion rate (efficacy. Secondary outcomes are elimination of hemorrhage risk factors (coexisting aneurysms and arteriovenous fistula, volume reduction and remission of symptoms. Safety and efficacy of endovascular therapy, gamma knife surgery, and various combination modes of the two modalities will be compared. Operative complications and outcomes at pretreatment, post-treatment, at discharge and at 3 months, 6 months and 2 years follow-up intervals will be analyzed using the modified Rankin Scale (mRS. Discussion: The most confusion on BAVM treatment is whether to choose interventional therapy or medical therapy, and the choice of interventional therapy modes. This study will provide evidence for evaluating the safety and efficacy of microinvasive treatment in China, to characterize the microinvasive treatment strategy for BAVMs. Keywords: Brain arteriovenous malformation, Clinical trial, Endovascular therapy, Gamma knife, Safety, Efficacy

Gamma Knife Treatment of Growing Vestibular Schwannoma in Norway: A Prospective Study

International Nuclear Information System (INIS)

Varughese, Jobin Kotakkathu; Wentzel-Larsen, Tore; Pedersen, Paal-Henning; Mahesparan, Ruby; Lund-Johansen, Morten

2012-01-01

Purpose: Gamma Knife radiosurgery (GKRS) has been increasingly used in the treatment of vestibular schwannoma (VS). Very few studies relate tumor control and post-treatment growth rates to pretreatment growth rates. Methods and Materials: We prospectively included 45 consecutive VS patients who were initially treated conservatively and then received GKRS between 2000 and 2007 because of demonstrated tumor growth. Pretreatment and post-treatment tumor volumes were estimated. Patients underwent audiograms, reported their symptoms, and responded to the Short Form General Health Survey (SF-36) questionnaire on each visit. Results: Volume doubling times before and after treatment were 1.36 years (95% confidence intervals, 1.14-1.68) and −13.1 years (95% confidence intervals, −111.0 to −6.94), respectively. Tumor control, defined as a post-GKRS growth rate ≤0, was achieved in 71.1% of patients, with highest odds for tumor control among older patients and those with larger tumors. The 5-year retreatment-free survival rate was 93.9% (95% confidence intervals, 76.5-98.5). None of the clinical endpoints investigated showed statistically significant changes after GKRS, but improvement was seen in a few SF-36 parameters. Conclusions: GKRS alters the natural course of the tumor by reducing growth. Mathematic models yield poorer tumor control rates than those found by clinical assessment. Symptoms were unaffected by treatment, but quality of life was improved.

Gamma Knife Treatment of Growing Vestibular Schwannoma in Norway: A Prospective Study

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Varughese, Jobin Kotakkathu, E-mail: jobinv@gmail.com [Institute of Surgical Sciences, University of Bergen, Bergen (Norway); Wentzel-Larsen, Tore [Centre for Clinical Research, Haukeland University Hospital, Bergen (Norway); Centre for Child and Adolescent Mental Health, Eastern and Southern Norway, Oslo (Norway); Norwegian Centre for Violence and Traumatic Stress Studies, Oslo (Norway); Pedersen, Paal-Henning [Institute of Surgical Sciences, University of Bergen, Bergen (Norway); Department of Neurosurgery, Haukeland University Hospital, Bergen (Norway); Mahesparan, Ruby [Department of Neurosurgery, Haukeland University Hospital, Bergen (Norway); Lund-Johansen, Morten [Institute of Surgical Sciences, University of Bergen, Bergen (Norway); Department of Neurosurgery, Haukeland University Hospital, Bergen (Norway)

2012-10-01

Purpose: Gamma Knife radiosurgery (GKRS) has been increasingly used in the treatment of vestibular schwannoma (VS). Very few studies relate tumor control and post-treatment growth rates to pretreatment growth rates. Methods and Materials: We prospectively included 45 consecutive VS patients who were initially treated conservatively and then received GKRS between 2000 and 2007 because of demonstrated tumor growth. Pretreatment and post-treatment tumor volumes were estimated. Patients underwent audiograms, reported their symptoms, and responded to the Short Form General Health Survey (SF-36) questionnaire on each visit. Results: Volume doubling times before and after treatment were 1.36 years (95% confidence intervals, 1.14-1.68) and -13.1 years (95% confidence intervals, -111.0 to -6.94), respectively. Tumor control, defined as a post-GKRS growth rate {<=}0, was achieved in 71.1% of patients, with highest odds for tumor control among older patients and those with larger tumors. The 5-year retreatment-free survival rate was 93.9% (95% confidence intervals, 76.5-98.5). None of the clinical endpoints investigated showed statistically significant changes after GKRS, but improvement was seen in a few SF-36 parameters. Conclusions: GKRS alters the natural course of the tumor by reducing growth. Mathematic models yield poorer tumor control rates than those found by clinical assessment. Symptoms were unaffected by treatment, but quality of life was improved.

Gamma Knife radiosurgery for the treatment of intracranial dural arteriovenous fistulas

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Dmytriw, Adam A; Schwartz, Michael L; Cusimano, Michael D; Mendes Pereira, Vitor; Krings, Timo; Tymianski, Michael; Radovanovic, Ivan

2016-01-01

Background Intracranial dural arteriovenous fistulae (DAVF) may present a treatment challenge. Endovascular embolization is in most cases the first line of treatment but does not always achieve cure. Gamma Knife (GK) radiosurgery represents an alternative treatment option, and the purpose of this study was to further evaluate its utility. Methods We reviewed all cases of DAVF treated between 2009 and 2016 at our institution with GK radiosurgery independently, or following failed/refused endovascular or surgical management. Patients’ clinical files, radiological images, catheter angiograms, and surgical DAVF disconnection reports were retrospectively reviewed. Results Sixteen DAVF (14 patients) treated by GK radiosurgery were identified. Eleven fistulae were aggressive and five were benign. Marginal doses ranged from 15 to 25 Gy. Target volumes ranged from 0.04 to 4.47 cm3. In all symptomatic patients, GK treatment resulted in symptom palliation. In 13/15 lesions, cure of symptoms (86.0%) was reported. One lesion was asymptomatic. Angiographic cure was achieved in eight cases (50%), small residual DAVF occurred in four, and four were unchanged. One patient developed headache that resolved at one year. No hemorrhage occurred during the follow-up period. There was no significant association between Borden type and cure rate. Prior failed endovascular treatment and small target volume were associated with lower rates of cure. Conclusions Stereotactic radiosurgery is viable treatment for DAVF. It is very effective in palliating symptoms as a de novo approach or adjunctive to endovascular therapy. In our experience it is only somewhat effective in achieving complete angiographic cure. PMID:28156167

Probability of obliteration and management risk following gamma knife surgery for cerebral AVM

International Nuclear Information System (INIS)

Karlsson, B.; Lax, I.

1998-01-01

In order to define the optimal treatment for an AVM patient, the probability of cure and the management risk following the treatment must be estimated before the treatment. Here, Gamma Knife surgery has an advantage over microsurgery and embolization with it's reproducibility within the variability of the individual radiation sensitivity. Based on more than 2000 treatments, we have developed models to predict the probability for obliteration, the risk for radioinduced complications and the probability for a post treatment hemorrhage within the first two years following a Gamma Knife treatment. The factors determining the overall outcome are the absorbed dose in the target and the brain, the AVM volume and location and the age and clinical history of the patient. The probability for obliteration equals 35,69 * ln(D min )-39,66 and is AVM volume independent. The risk for radioinduced complications relates to the average dose in the 20 cm 3 tissue receiving the most radiation, and it is also related to the clinical history of the patient and the AVM location. Finally, the risk for post treatment hemorrhage increases with the age of the patient, and is higher for larger AVM. It decreases with increasing amount of radiation given, and it is independent of the clinical history of the patient. For retreatments, the model for prediction of obliteration is valid, but the risk for radioinduced complications is higher and the risk for post treatment hemorrhage lower as compared to following the first treatment. (author)

Gamma Knife surgery for clival epidural-osseous dural arteriovenous fistulas.

Science.gov (United States)

Lee, Cheng-Chia; Chen, Ching-Jen; Chen, Shao-Ching; Yang, Huai-Che; Lin, Chung Jung; Wu, Chih-Chun; Chung, Wen-Yuh; Guo, Wan-Yuo; Hung-Chi Pan, David; Shiau, Cheng-Ying; Wu, Hsiu-Mei

2018-05-01

OBJECTIVE Clival epidural-osseous dural arteriovenous fistula (DAVF) is often associated with a large nidus, multiple arterial feeders, and complex venous drainage. In this study the authors report the outcomes of clival epidural-osseous DAVFs treated using Gamma Knife surgery (GKS). METHODS Thirteen patients with 13 clival epidural-osseous DAVFs were treated with GKS at the authors' institution between 1993 and 2015. Patient age at the time of GKS ranged from 38 to 76 years (median 55 years). Eight DAVFs were classified as Cognard Type I, 4 as Type IIa, and 1 as Type IIa+b. The median treatment volume was 17.6 cm 3 (range 6.2-40.3 cm 3 ). The median prescribed margin dose was 16.5 Gy (range 15-18 Gy). Clinical and radiological follow-ups were performed at 6-month intervals. Patient outcomes after GKS were categorized as 1) complete improvement, 2) partial improvement, 3) stationary, and 4) progression. RESULTS All 13 patients demonstrated symptomatic improvement, and on catheter angiography 12 of the 13 patients had complete obliteration and 1 patient had partial obliteration. The median follow-up period was 26 months (range 14-186 months). The median latency period from GKS to obliteration was 21 months (range 8-186 months). There was no intracranial hemorrhage during the follow-up period, and no deaths occurred. Two adverse events were observed following treatment, and 2 patients required repeat GKS treatment with eventual complete obliteration. CONCLUSIONS Gamma Knife surgery offers a safe and effective primary or adjuvant treatment modality for complex clival epidural-osseous DAVFs. All patients in this case series demonstrated symptomatic improvement, and almost all patients attained complete obliteration.

Gamma Knife Radiosurgery for Cushing's Disease and Nelson's Syndrome

Czech Academy of Sciences Publication Activity Database

Marek, J.; Ježková, J.; Hána, V.; Kršek, M.; Liščák, R.; Vladyka, V.; Pecen, Ladislav

2015-01-01

Roč. 18, č. 3 (2015), s. 376-384 ISSN 1386-341X Institutional support: RVO:67985807 Keywords : Cushing's disease * Nelson's syndrome * Gamma knife surgery * Pituitary adenoma Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 3.407, year: 2015

Single-session Gamma Knife radiosurgery for optic pathway/hypothalamic gliomas.

Science.gov (United States)

El-Shehaby, Amr M N; Reda, Wael A; Abdel Karim, Khaled M; Emad Eldin, Reem M; Nabeel, Ahmed M

2016-12-01

OBJECTIVE Because of their critical and central location, it is deemed necessary to fractionate when considering irradiating optic pathway/hypothalamic gliomas. Stereotactic fractionated radiotherapy is considered safer when dealing with gliomas in this location. In this study, the safety and efficacy of single-session stereotactic radiosurgery for optic pathway/hypothalamic gliomas were reviewed. METHODS Between December 2004 and June 2014, 22 patients with optic pathway/hypothalamic gliomas were treated by single-session Gamma Knife radiosurgery. Twenty patients were available for follow-up for a minimum of 1 year after treatment. The patients were 5 to 43 years (median 16 years) of age. The tumor volume was 0.15 to 18.2 cm 3 (median 3.1 cm 3 ). The prescription dose ranged from 8 to 14 Gy (median 11.5 Gy). RESULTS The mean follow-up period was 43 months. Five tumors involved the optic nerve only, and 15 tumors involved the chiasm/hypothalamus. Two patients died during the follow-up period. The tumors shrank in 12 cases, remained stable in 6 cases, and progressed in 2 cases, thereby making the tumor control rate 90%. Vision remained stable in 12 cases, improved in 6 cases, and worsened in 2 cases in which there was tumor progression. Progression-free survival was 83% at 3 years. CONCLUSIONS The initial results indicate that single-session Gamma Knife radiosurgery is a safe and effective treatment option for optic pathway/hypothalamic gliomas.

Gamma knife stereotactic radiosurgical thalamotomy for intractable tremor: A systematic review of the literature

International Nuclear Information System (INIS)

Campbell, Allison M.; Glover, Janis; Chiang, Veronica L.S.; Gerrard, Jason; Yu, James B.

2015-01-01

Tremor markedly reduces quality of life and causes a significant psychological burden for patients who are severely affected by this movement disorder. Pharmacologic and surgical treatments for tremor exist, but for patients who have failed medical therapy and are not surgical candidates, stereotactic radiosurgery is the only available treatment option. Of available stereotactic radiosurgical techniques for intractable tremor, the authors chose to evaluate the safety and efficacy of gamma knife stereotactic radiosurgical thalamotomy. In order to qualitatively synthesize available data a systematic review was conducted by searching MEDLINE (OvidSP 1946–January Week 1 2014) and Embase (OvidSP 1974–2014 January). The search strategy was not limited by study design or language of publication. All searches were conducted on January 7, 2014. Treatment efficacy, adverse outcomes, and patient deaths were reviewed and tabulated. Complications appeared months to years post procedure and most commonly consisted of mild contralateral numbness and transient hemiparesis. Rarely, more severe complications were reported, including dysphagia and death. Though no data from randomized controlled trials are available, our analysis of the literature indicates that unilateral gamma knife thalamotomy using doses from 130 to 150 Gy appears safe and well tolerated

Worldwide variance in the potential utilization of Gamma Knife radiosurgery.

Science.gov (United States)

Hamilton, Travis; Dade Lunsford, L

2016-12-01

OBJECTIVE The role of Gamma Knife radiosurgery (GKRS) has expanded worldwide during the past 3 decades. The authors sought to evaluate whether experienced users vary in their estimate of its potential use. METHODS Sixty-six current Gamma Knife users from 24 countries responded to an electronic survey. They estimated the potential role of GKRS for benign and malignant tumors, vascular malformations, and functional disorders. These estimates were compared with published disease epidemiological statistics and the 2014 use reports provided by the Leksell Gamma Knife Society (16,750 cases). RESULTS Respondents reported no significant variation in the estimated use in many conditions for which GKRS is performed: meningiomas, vestibular schwannomas, and arteriovenous malformations. Significant variance in the estimated use of GKRS was noted for pituitary tumors, craniopharyngiomas, and cavernous malformations. For many current indications, the authors found significant variance in GKRS users based in the Americas, Europe, and Asia. Experts estimated that GKRS was used in only 8.5% of the 196,000 eligible cases in 2014. CONCLUSIONS Although there was a general worldwide consensus regarding many major indications for GKRS, significant variability was noted for several more controversial roles. This expert opinion survey also suggested that GKRS is significantly underutilized for many current diagnoses, especially in the Americas. Future studies should be conducted to investigate health care barriers to GKRS for many patients.

Optic neuritis in a case after gamma knife radiosurgery for relapsed pituitary adenoma

International Nuclear Information System (INIS)

Hosoda, Atsuhide; Mizunoya, Satoshi; Abe, Hideki; Kanai, Hidehito; Ikeda, Kazutoshi; Kidahashi, Hisaharu; Suzuki, Masanobu

2008-01-01

The purpose of this study was to report a case of optic neuritis after gamma knife radiosurgery for pituitary adenoma. A 41-year-old woman presented with impaired vision in both eyes since 5 days before. She had received surgery for pituitary tumor 5 years before. She was treated by gamma knife radiosurgery for relapse of tumor 50 days before. Her corrected visual acuity was 0.5 right and 0.6 left. She had abnormal color sense. Flicker fusion frequency was decreased in both eyes. Both eyes showed enlarged blind spot and relative scotoma in the superior sector. Magnetic resonance imaging (MRI) showed enhanced signal in the optic nerve sheath. These findings led to the diagnosis of optic neuritis. Pulsed corticosteroid therapy was followed by improved vision of 1.2 in either eye. She has been doing well for 18 months until present. This case illustrates that optic neuritis may develop after gamma knife radiosurgery. (author)

Adaptive fractionated stereotactic Gamma Knife radiotherapy of meningioma using integrated stereotactic cone-beam-CT and adaptive re-planning (a-gkFSRT).

Science.gov (United States)

Stieler, F; Wenz, F; Abo-Madyan, Y; Schweizer, B; Polednik, M; Herskind, C; Giordano, F A; Mai, S

2016-11-01

The Gamma Knife Icon (Elekta AB, Stockholm, Sweden) allows frameless stereotactic treatment using a combination of cone beam computer tomography (CBCT), a thermoplastic mask system, and an infrared-based high-definition motion management (HDMM) camera system for patient tracking during treatment. We report on the first patient with meningioma at the left petrous bone treated with adaptive fractionated stereotactic radiotherapy (a-gkFSRT). The first patient treated with Gamma Knife Icon at our institute received MR imaging for preplanning before treatment. For each treatment fraction, a daily CBCT was performed to verify the actual scull/tumor position. The system automatically adapted the planned shot positions to the daily position and recalculated the dose distribution (online adaptive planning). During treatment, the HDMM system recorded the intrafractional patient motion. Furthermore, the required times were recorded to define a clinical treatment slot. Total treatment time was around 20 min. Patient positioning needed 0.8 min, CBCT positioning plus acquisition 1.65 min, CT data processing and adaptive planning 2.66 min, and treatment 15.6 min. The differences for the five daily CBCTs compared to the reference are for rotation: -0.59 ± 0.49°/0.18 ± 0.20°/0.05 ± 0.36° and for translation: 0.94 ± 0.52 mm/-0.08 ± 0.08 mm/-1.13 ± 0.89 mm. Over all fractions, an intrafractional movement of 0.13 ± 0.04 mm was observed. The Gamma Knife Icon allows combining the accuracy of the stereotactic Gamma Knife system with the flexibility of fractionated treatment with the mask system and CBCT. Furthermore, the Icon system introduces a new online patient tracking system to the clinical routine. The interfractional accuracy of patient positioning was controlled with a thermoplastic mask and CBCT.

Optimal Shape of a Gamma-ray Collimator: single vs double knife edge

Science.gov (United States)

Metz, Albert; Hogenbirk, Alfred

2017-09-01

Gamma-ray collimators in nuclear waste scanners are used for selecting a narrow vertical segment in activity measurements of waste vessels. The system that is used by NRG uses tapered slit collimators of both the single and double knife edge type. The properties of these collimators were investigated by means of Monte Carlo simulations. We found that single knife edge collimators are highly preferable for a conservative estimate of the activity of the waste vessels. These collimators show much less dependence on the angle of incidence of the radiation than double knife edge collimators. This conclusion also applies to cylindrical collimators of the single knife edge type, that are generally used in medical imaging spectroscopy.

Monte Carlo simulation of the Leksell Gamma Knife: I. Source modelling and calculations in homogeneous media

Energy Technology Data Exchange (ETDEWEB)

Moskvin, Vadim [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States)]. E-mail: vmoskvin@iupui.edu; DesRosiers, Colleen; Papiez, Lech; Timmerman, Robert; Randall, Marcus; DesRosiers, Paul [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States)

2002-06-21

The Monte Carlo code PENELOPE has been used to simulate photon flux from the Leksell Gamma Knife, a precision method for treating intracranial lesions. Radiation from a single {sup 60}Co assembly traversing the collimator system was simulated, and phase space distributions at the output surface of the helmet for photons and electrons were calculated. The characteristics describing the emitted final beam were used to build a two-stage Monte Carlo simulation of irradiation of a target. A dose field inside a standard spherical polystyrene phantom, usually used for Gamma Knife dosimetry, has been computed and compared with experimental results, with calculations performed by other authors with the use of the EGS4 Monte Carlo code, and data provided by the treatment planning system Gamma Plan. Good agreement was found between these data and results of simulations in homogeneous media. Owing to this established accuracy, PENELOPE is suitable for simulating problems relevant to stereotactic radiosurgery. (author)

Treatment selection for unruptured small cerebral arteriovenous malformations with clinical decision analysis. Observation, gamma knife or microsurgery?

International Nuclear Information System (INIS)

Serizawa, Toru; Higuchi, Yoshinori; Ono, Junichi

2006-01-01

We present an optimal treatment for unruptured small (3 cm or less) cerebral arteriovenous malformations (AVM) among conservative treatment, gamma knife surgery (GKS) and microsurgery using clinical decision analysis according to patients' age. All cases for this study were small AVMs. We analyzed 973 cases with conservative treatment, 176 with GKS and 110 with microsurgery. The expected utility indexes were calculated from the results of each group. We hypothesized the standardized expected utility indexes as 100 in healthy, 75 in disabled and 0 in dead. Microsurgery was the first choice for patients younger than 55 years with AVM located in a surgically accessible region. GKS is recommended for patients aged between 55 and 70, and the best treatment is observation for patients older than 70 years. The proposed clinical decision analysis is very useful in obtaining informed consent for choosing the treatment modality for unruptured small AVM. (author)

SU-E-T-213: Comparison of Treatment Efficiency of Gamma Knife SRS Plans for Brain Metastases with Different Planning Methods

Energy Technology Data Exchange (ETDEWEB)

Feng, Y [East Carolina Univ, Greenville, NC (United States); Huang, Z [East Carolina University, Greenville, NC (United States); Lo, S [Case Western Reserve University, Cleveland, OH (United States); Mayr, N; Yuh, W [University of Washington, Seattle, WA (United States)

2015-06-15

Purpose: To improve Gamma Knife SRS treatment efficiency for brain metastases and compare the differences of treatment time and radiobiological effects between two different planning methods of automatic filling and manual placement of shots with inverse planning. Methods: T1-weighted MRI images with gadolinium contrast from five patients with a single brain metastatic-lesion were used in this retrospective study. Among them, two were from primary breast cancer, two from primary melanoma cancer and one from primary prostate cancer. For each patient, two plans were generated in Leksell GammaPlan10.1.1 for radiosurgical treatment with a Leksell GammaKnife Perfexion machine: one with automatic filling, automatic sector configuration and inverse optimization (Method1); and the other with manual placement of shots, manual setup of collimator sizes, manual setup of sector blocking and inverse optimization (Method2). Dosimetric quality of the plans was evaluated with parameters of Coverage, Selectivity, Gradient-Index and DVH. Beam-on Time, Number-of-Shots and Tumor Control Probability(TCP) were compared for the two plans while keeping their dosimetric quality very similar. Relative reduction of Beam-on Time and Number-of-Shots were calculated as the ratios among the two plans and used for quantitative analysis. Results: With very similar dosimetric and radiobiological plan quality, plans created with Method 2 had significantly reduced treatment time. Relative reduction of Beam-on Time ranged from 20% to 51 % (median:29%,p=0.001), and reduction of Number-of-Shots ranged from 5% to 67% (median:40%,p=0.0002), respectively. Time of plan creation for Method1 and Method2 was similar, approximately 20 minutes, excluding the time for tumor delineation. TCP calculated for the tumors from differential DVHs did not show significant difference between the two plans (p=0.35). Conclusion: The method of manual setup combined with inverse optimization in LGP for treatment of brain

SU-E-T-213: Comparison of Treatment Efficiency of Gamma Knife SRS Plans for Brain Metastases with Different Planning Methods

International Nuclear Information System (INIS)

Feng, Y; Huang, Z; Lo, S; Mayr, N; Yuh, W

2015-01-01

Purpose: To improve Gamma Knife SRS treatment efficiency for brain metastases and compare the differences of treatment time and radiobiological effects between two different planning methods of automatic filling and manual placement of shots with inverse planning. Methods: T1-weighted MRI images with gadolinium contrast from five patients with a single brain metastatic-lesion were used in this retrospective study. Among them, two were from primary breast cancer, two from primary melanoma cancer and one from primary prostate cancer. For each patient, two plans were generated in Leksell GammaPlan10.1.1 for radiosurgical treatment with a Leksell GammaKnife Perfexion machine: one with automatic filling, automatic sector configuration and inverse optimization (Method1); and the other with manual placement of shots, manual setup of collimator sizes, manual setup of sector blocking and inverse optimization (Method2). Dosimetric quality of the plans was evaluated with parameters of Coverage, Selectivity, Gradient-Index and DVH. Beam-on Time, Number-of-Shots and Tumor Control Probability(TCP) were compared for the two plans while keeping their dosimetric quality very similar. Relative reduction of Beam-on Time and Number-of-Shots were calculated as the ratios among the two plans and used for quantitative analysis. Results: With very similar dosimetric and radiobiological plan quality, plans created with Method 2 had significantly reduced treatment time. Relative reduction of Beam-on Time ranged from 20% to 51 % (median:29%,p=0.001), and reduction of Number-of-Shots ranged from 5% to 67% (median:40%,p=0.0002), respectively. Time of plan creation for Method1 and Method2 was similar, approximately 20 minutes, excluding the time for tumor delineation. TCP calculated for the tumors from differential DVHs did not show significant difference between the two plans (p=0.35). Conclusion: The method of manual setup combined with inverse optimization in LGP for treatment of brain

MO-F-CAMPUS-T-03: Continuous Dose Delivery with Gamma Knife Perfexion

International Nuclear Information System (INIS)

Ghobadi,; Li, W; Chung, C; Jaffray, D; Aleman, D

2015-01-01

Purpose: We propose continuous dose delivery techniques for stereotactic treatments delivered by Gamma Knife Perfexion using inverse treatment planning system that can be applied to various tumour sites in the brain. We test the accuracy of the plans on Perfexion’s planning system (GammaPlan) to ensure the obtained plans are viable. This approach introduces continuous dose delivery for Perefxion, as opposed to the currently employed step-and-shoot approaches, for different tumour sites. Additionally, this is the first realization of automated inverse planning on GammaPlan. Methods: The inverse planning approach is divided into two steps of identifying a quality path inside the target, and finding the best collimator composition for the path. To find a path, we select strategic regions inside the target volume and find a path that visits each region exactly once. This path is then passed to a mathematical model which finds the best combination of collimators and their durations. The mathematical model minimizes the dose spillage to the surrounding tissues while ensuring the prescribed dose is delivered to the target(s). Organs-at-risk and their corresponding allowable doses can also be added to the model to protect adjacent organs. Results: We test this approach on various tumour sizes and sites. The quality of the obtained treatment plans are comparable or better than forward plans and inverse plans that use step- and-shoot technique. The conformity indices in the obtained continuous dose delivery plans are similar to those of forward plans while the beam-on time is improved on average (see Table 1 in supporting document). Conclusion: We employ inverse planning for continuous dose delivery in Perfexion for brain tumours. The quality of the obtained plans is similar to forward and inverse plans that use conventional step-and-shoot technique. We tested the inverse plans on GammaPlan to verify clinical relevance. This research was partially supported by Elekta

MO-F-CAMPUS-T-03: Continuous Dose Delivery with Gamma Knife Perfexion

Energy Technology Data Exchange (ETDEWEB)

Ghobadi,; Li, W; Chung, C; Jaffray, D [Princess Margaret Cancer Centre and University Health Network, Toronto, Ontario (Canada); Aleman, D [University of Toronto, Toronto, Ontario (Canada)

2015-06-15

Purpose: We propose continuous dose delivery techniques for stereotactic treatments delivered by Gamma Knife Perfexion using inverse treatment planning system that can be applied to various tumour sites in the brain. We test the accuracy of the plans on Perfexion’s planning system (GammaPlan) to ensure the obtained plans are viable. This approach introduces continuous dose delivery for Perefxion, as opposed to the currently employed step-and-shoot approaches, for different tumour sites. Additionally, this is the first realization of automated inverse planning on GammaPlan. Methods: The inverse planning approach is divided into two steps of identifying a quality path inside the target, and finding the best collimator composition for the path. To find a path, we select strategic regions inside the target volume and find a path that visits each region exactly once. This path is then passed to a mathematical model which finds the best combination of collimators and their durations. The mathematical model minimizes the dose spillage to the surrounding tissues while ensuring the prescribed dose is delivered to the target(s). Organs-at-risk and their corresponding allowable doses can also be added to the model to protect adjacent organs. Results: We test this approach on various tumour sizes and sites. The quality of the obtained treatment plans are comparable or better than forward plans and inverse plans that use step- and-shoot technique. The conformity indices in the obtained continuous dose delivery plans are similar to those of forward plans while the beam-on time is improved on average (see Table 1 in supporting document). Conclusion: We employ inverse planning for continuous dose delivery in Perfexion for brain tumours. The quality of the obtained plans is similar to forward and inverse plans that use conventional step-and-shoot technique. We tested the inverse plans on GammaPlan to verify clinical relevance. This research was partially supported by Elekta

Gamma knife radiosurgery for trigeminal neuralgia

International Nuclear Information System (INIS)

Tomida, Mihoko; Hayashi, Motohiro; Kawakami, Yoriko; Ishimaru, Jun-ichi

2009-01-01

Gamma knife surgery (GKS) has been employed for treating intractable pain such as trigeminal neuralgia (TN) and pain relief has been gained from the treatment, however, little is understood about the side effects of other sensitivities induced from GKS. We assessed ten patients (four men and six women; mean age 67 years) with TN who were investigated by questionnaire for symptoms and visual analog scale (VAS) of pain, and their threshold of touch sensation was examined using Semmes-Weinstein monofilaments, cold sensation and allodynia before and after GKS. MR and CT images were obtained after a Leksell head frame was applied to the head parallel to the trigeminal nerve. These images were uploaded to a computer system and retro-Gasserian area planned the target was correctly marked on the images of a computer in which gamma planning software was installed. All patients were irradiated with a maximum dose of 90 Gy at retro-Gasserian using a 4 mm collimator. The mean±standard deviation (SD) of VAS of pain was 8.5±1.3 and 8 patients had facial paresthesia before GKS. All patients experienced a significant reduction in pain without side effects such as effect on the peripheral nerves without 6 month after GKS. Allodynia, facial paresthesia or cold sensation numbness occurred in the patients before GKS disappeared according to complete pain relief. These results suggest that GKS is a safe and effective treatment for TN. (author)

A virtual source method for Monte Carlo simulation of Gamma Knife Model C

Energy Technology Data Exchange (ETDEWEB)

Kim, Tae Hoon; Kim, Yong Kyun [Hanyang University, Seoul (Korea, Republic of); Chung, Hyun Tai [Seoul National University College of Medicine, Seoul (Korea, Republic of)

2016-05-15

The Monte Carlo simulation method has been used for dosimetry of radiation treatment. Monte Carlo simulation is the method that determines paths and dosimetry of particles using random number. Recently, owing to the ability of fast processing of the computers, it is possible to treat a patient more precisely. However, it is necessary to increase the simulation time to improve the efficiency of accuracy uncertainty. When generating the particles from the cobalt source in a simulation, there are many particles cut off. So it takes time to simulate more accurately. For the efficiency, we generated the virtual source that has the phase space distribution which acquired a single gamma knife channel. We performed the simulation using the virtual sources on the 201 channel and compared the measurement with the simulation using virtual sources and real sources. A virtual source file was generated to reduce the simulation time of a Gamma Knife Model C. Simulations with a virtual source executed about 50 times faster than the original source code and there was no statistically significant difference in simulated results.

A virtual source method for Monte Carlo simulation of Gamma Knife Model C

International Nuclear Information System (INIS)

Kim, Tae Hoon; Kim, Yong Kyun; Chung, Hyun Tai

2016-01-01

The Monte Carlo simulation method has been used for dosimetry of radiation treatment. Monte Carlo simulation is the method that determines paths and dosimetry of particles using random number. Recently, owing to the ability of fast processing of the computers, it is possible to treat a patient more precisely. However, it is necessary to increase the simulation time to improve the efficiency of accuracy uncertainty. When generating the particles from the cobalt source in a simulation, there are many particles cut off. So it takes time to simulate more accurately. For the efficiency, we generated the virtual source that has the phase space distribution which acquired a single gamma knife channel. We performed the simulation using the virtual sources on the 201 channel and compared the measurement with the simulation using virtual sources and real sources. A virtual source file was generated to reduce the simulation time of a Gamma Knife Model C. Simulations with a virtual source executed about 50 times faster than the original source code and there was no statistically significant difference in simulated results

Feasibility of identification of gamma knife planning strategies by identification of pareto optimal gamma knife plans.

Science.gov (United States)

Giller, C A

2011-12-01

The use of conformity indices to optimize Gamma Knife planning is common, but does not address important tradeoffs between dose to tumor and normal tissue. Pareto analysis has been used for this purpose in other applications, but not for Gamma Knife (GK) planning. The goal of this work is to use computer models to show that Pareto analysis may be feasible for GK planning to identify dosimetric tradeoffs. We define a GK plan A to be Pareto dominant to B if the prescription isodose volume of A covers more tumor but not more normal tissue than B, or if A covers less normal tissue but not less tumor than B. A plan is Pareto optimal if it is not dominated by any other plan. Two different Pareto optimal plans represent different tradeoffs between dose to tumor and normal tissue, because neither plan dominates the other. 'GK simulator' software calculated dose distributions for GK plans, and was called repetitively by a genetic algorithm to calculate Pareto dominant plans. Three irregular tumor shapes were tested in 17 trials using various combinations of shots. The mean number of Pareto dominant plans/trial was 59 ± 17 (sd). Different planning strategies were identified by large differences in shot positions, and 70 of the 153 coordinate plots (46%) showed differences of 5mm or more. The Pareto dominant plans dominated other nearby plans. Pareto dominant plans represent different dosimetric tradeoffs and can be systematically calculated using genetic algorithms. Automatic identification of non-intuitive planning strategies may be feasible with these methods.

Gamma Knife irradiation method based on dosimetric controls to target small areas in rat brains

International Nuclear Information System (INIS)

Constanzo, Julie; Paquette, Benoit; Charest, Gabriel; Masson-Côté, Laurence; Guillot, Mathieu

2015-01-01

Purpose: Targeted and whole-brain irradiation in humans can result in significant side effects causing decreased patient quality of life. To adequately investigate structural and functional alterations after stereotactic radiosurgery, preclinical studies are needed. The purpose of this work is to establish a robust standardized method of targeted irradiation on small regions of the rat brain. Methods: Euthanized male Fischer rats were imaged in a stereotactic bed, by computed tomography (CT), to estimate positioning variations relative to the bregma skull reference point. Using a rat brain atlas and the stereotactic bregma coordinates obtained from CT images, different regions of the brain were delimited and a treatment plan was generated. A single isocenter treatment plan delivering ≥100 Gy in 100% of the target volume was produced by Leksell GammaPlan using the 4 mm diameter collimator of sectors 4, 5, 7, and 8 of the Gamma Knife unit. Impact of positioning deviations of the rat brain on dose deposition was simulated by GammaPlan and validated with dosimetric measurements. Results: The authors’ results showed that 90% of the target volume received 100 ± 8 Gy and the maximum of deposited dose was 125 ± 0.7 Gy, which corresponds to an excellent relative standard deviation of 0.6%. This dose deposition calculated with GammaPlan was validated with dosimetric films resulting in a dose-profile agreement within 5%, both in X- and Z-axes. Conclusions: The authors’ results demonstrate the feasibility of standardizing the irradiation procedure of a small volume in the rat brain using a Gamma Knife

Indications of Gamma knife radiosurgery for vestibular schwannomas

International Nuclear Information System (INIS)

Fukuoka, Seiji; Takanashi, Masami; Hojyo, Atsufumi; Tanaka, Chiharu; Konishi, Masanori; Nakamura, Hirohiko

2007-01-01

The purpose of this study was to investigate the indication of gamma knife radiosurgery for vestibular schwannomas by analyzing tumor control and possible complications using low marginal doses and conformal multiple shots to fit irregular tumor shapes. The authors evaluated 223 patients with followed-up periods ranging from 5 years to 15 years (mean 7.7 years, median 7.4 years). Marginal doses were 9 to 15 Gy (mean 12.5 Gy, median 12 Gy) with corresponding treatment volumes being between 0.1 and 18.7 cm 3 (mean 2.6 cm 3 , median 1.8 cm 3 ). The number of isocenters varied from 2 to 24 shots (mean 9, median 9.2). The actuarial tumor control rates were 95% at 5 years and 94% at 7 years, respectively. Larger tumors (p=0.0068) and those in younger patients (p=0.093) tended to recur significantly. The preservation rates of useful hearing were 84%, 71%, and 64% at 2, 4, and 7 years, respectively. The most deterioration seemed to occur in cases with elderly patients (p=0.0048). Facial and trigeminal functions were preserved at 100%, and 97.8%, respectively. Amongst all patients, 20.6% developed transient dizziness, with persistent dizziness remaining in 1.5% of the total. Fifty-six other patients not in the long-term evaluation consecutively underwent caloric testing and static stabilometry as well as neurological examinations to evaluate vestibular function in detail, both before and after gamma knife radiosurgery (GKRS). The results showed that 90% of the patients had already developed vestibular dysfunction before the treatment despite reported symptoms of dizziness. GKRS did not significantly affect vestibular function. Hydrocephalus was recognized in 5.5% of all patients, and seemed to occur primarily in cases with larger tumors (p=0.0189). GKRS provides a safe and effective therapy for small to medium sized tumors up to 8 cm 3 . Long-term hearing preservation rate may be affected by presbycusis in elderly patients. (author)

A case of acoustic neurinoma associated with chronic subdural hematoma after gamma knife radiosurgery

International Nuclear Information System (INIS)

Sho, Atsuko; Asaeda, Masahiro; Ohtake, Minoru

2002-01-01

A 72-year-old female presented with a unique case of acoustic neurinoma with a cystic component followed by the chronic subdural hematoma manifesting as trigeminal neuralgia, facial palsy and trunchal ataxia 7 months after gamma knife radiosurgery. Magnetic resonance imaging demonstrated a loss of central contrast enhancement at the postoperative residual tumor mass and a large cyst associated with a hematoma in the subdural space. A right suboccipital craniectomy was performed. A biopsy of the mass and the membrane was performed following aspiration of the brown-reddish fluid collection. The histological diagnosis was acoustic neurinoma with a hemorrhagic necrosis. The membranous tissue mimicked an outer membrane obtained from chronic subdural hematoma. The postoperative course was satisfactory and preoperative symptom have been alleviated. In this case, the chronic subdural hematoma occurred at posterior fossa during the development of cysts caused by the radiosurgery, because the subdural space had been connected with the subarachnoid space after the first operation. The development of cysts or hematoma should be taken into consideration as possible complications following treatment with gamma knife radiosurgery for acoustic neurinomas. (author)

A case of acoustic neurinoma associated with chronic subdural hematoma after gamma knife radiosurgery

Energy Technology Data Exchange (ETDEWEB)

Sho, Atsuko; Asaeda, Masahiro; Ohtake, Minoru [Tottori Univ., Yonago (Japan). Inst. of Neurological Sciences] [and others

2002-09-01

A 72-year-old female presented with a unique case of acoustic neurinoma with a cystic component followed by the chronic subdural hematoma manifesting as trigeminal neuralgia, facial palsy and trunchal ataxia 7 months after gamma knife radiosurgery. Magnetic resonance imaging demonstrated a loss of central contrast enhancement at the postoperative residual tumor mass and a large cyst associated with a hematoma in the subdural space. A right suboccipital craniectomy was performed. A biopsy of the mass and the membrane was performed following aspiration of the brown-reddish fluid collection. The histological diagnosis was acoustic neurinoma with a hemorrhagic necrosis. The membranous tissue mimicked an outer membrane obtained from chronic subdural hematoma. The postoperative course was satisfactory and preoperative symptom have been alleviated. In this case, the chronic subdural hematoma occurred at posterior fossa during the development of cysts caused by the radiosurgery, because the subdural space had been connected with the subarachnoid space after the first operation. The development of cysts or hematoma should be taken into consideration as possible complications following treatment with gamma knife radiosurgery for acoustic neurinomas. (author)

Dose verification to cochlea during gamma knife radiosurgery of acoustic schwannoma using MOSFET dosimeter.

Science.gov (United States)

Sharma, Sunil D; Kumar, Rajesh; Akhilesh, Philomina; Pendse, Anil M; Deshpande, Sudesh; Misra, Basant K

2012-01-01

Dose verification to cochlea using metal oxide semiconductor field effect transistor (MOSFET) dosimeter using a specially designed multi slice head and neck phantom during the treatment of acoustic schwannoma by Gamma Knife radiosurgery unit. A multi slice polystyrene head phantom was designed and fabricated for measurement of dose to cochlea during the treatment of the acoustic schwannoma. The phantom has provision to position the MOSFET dosimeters at the desired location precisely. MOSFET dosimeters of 0.2 mm x 0.2 mm x 0.5 μm were used to measure the dose to the cochlea. CT scans of the phantom with MOSFETs in situ were taken along with Leksell frame. The treatment plans of five patients treated earlier for acoustic schwannoma were transferred to the phantom. Dose and coordinates of maximum dose point inside the cochlea were derived. The phantom along with the MOSFET dosimeters was irradiated to deliver the planned treatment and dose received by cochlea were measured. The treatment planning system (TPS) estimated and measured dose to the cochlea were in the range of 7.4 - 8.4 Gy and 7.1 - 8 Gy, respectively. The maximum variation between TPS calculated and measured dose to cochlea was 5%. The measured dose values were found in good agreement with the dose values calculated using the TPS. The MOSFET dosimeter can be a suitable choice for routine dose verification in the Gamma Knife radiosurgery.

Association between neurovascular contact on MRI and response to gamma knife radiosurgery in trigeminal neuralgia

International Nuclear Information System (INIS)

Erbay, Sami H.; Bhadelia, Rafeeque A.; Gupta, Punita; O'Callaghan, Mark; Yun, Eric; Oljeski, Steven; Riesenburger, Ron

2006-01-01

Treatment with gamma knife radiosurgery (GKRS) provides adequate short-term pain control in about 70% of the patients with intractable trigeminal neuralgia (TN). The purpose of our study was to evaluate whether the presence of neurovascular contact (NVC) at the root entry zone of the trigeminal nerve on pre-gamma knife MR imaging predicts an increased likelihood of an adequate response to GKRS.We studied 40 consecutive patients who underwent GKRS for treatment of intractable TN. Two neuroradiologists blinded to the side of symptoms analyzed pre-treatment constructive interference in steady state (CISS) images to determine the presence of NVC by consensus. An adequate response was defined as freedom from pain with or without reduced need for medical therapy. Adequate short-term response to GKRS was seen in 29 (72.5%) of 40 patients. NVC was seen in 30 of the 40 patients. Twenty-five (83.3%) of 30 patients with NVC had adequate short-term response to GKRS. Only four (40%) of the 10 patients without NVC had adequate response to GKRS (X 2 =7.06; P<0.01). Patients with NVC were seven times more likely to have an adequate response to GKRS than those without NVC (odds ratio =7.5).The presence of NVC on pre-treatment MR imaging predicts an increased likelihood of an adequate response to GKRS. (orig.)

Clinical Outcomes of Gamma Knife Radiosurgery in the Treatment of Patients with Trigeminal Neuralgia

Science.gov (United States)

Elaimy, Ameer L.; Hanson, Peter W.; Lamoreaux, Wayne T.; Mackay, Alexander R.; Demakas, John J.; Fairbanks, Robert K.; Cooke, Barton S.; Thumma, Sudheer R.; Lee, Christopher M.

2012-01-01

Since its introduction by Leksell, Gamma Knife radiosurgery (GKRS) has become increasingly popular as a management approach for patients diagnosed with trigeminal neuralgia (TN). For this reason, we performed a modern review of the literature analyzing the efficacy of GKRS in the treatment of patients who suffer from TN. For patients with medically refractory forms of the condition, GKRS has proven to be an effective initial and repeat treatment option. Cumulative research suggests that patients treated a single time with GKRS exhibit similar levels of facial pain control when compared to patients treated multiple times with GKRS. However, patients treated on multiple occasions with GKRS are more likely to experience facial numbness and other facial sensory changes when compared to patients treated once with GKRS. Although numerous articles have reported MVD to be superior to GKRS in achieving facial pain relief, the findings of these comparison studies are weakened by the vast differences in patient age and comorbidities between the two studied groups and cannot be considered conclusive. Questions remain regarding optimal GKRS dosing and targeting strategies, which warrants further investigation into this controversial matter. PMID:22229034

Gamma Knife surgery for intracranial chordoma and chondrosarcoma: radiosurgical perspectives and treatment outcomes.

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Kim, Ji Hee; Jung, Hyun Ho; Chang, Jong Hee; Chang, Jin Woo; Park, Yong Gou; Chang, Won Seok

2014-12-01

Intracranial chordomas and chondrosarcomas are histologically low-grade, locally invasive tumors that are reported to be similar in terms of anatomical location, clinical presentation, and radiological findings but different in terms of behavior and outcomes. The purpose of this study was to investigate and compare clinical outcomes after Gamma Knife surgery (GKS) for the treatment of intracranial chordoma and chondrosarcoma. The authors conducted a retrospective review of the results of radiosurgical treatment of intracranial chordomas and chondrosarcomas. They enrolled patients who had undergone GKS for intracranial chordoma or chondrosarcoma at the Yonsei Gamma Knife Center, Yonsei University College of Medicine, from October 2000 through June 2007. Analyses included only patients for whom the disease was pathologically diagnosed before GKS and for whom more than 5 years of follow-up data after GKS were available. Rates of progression-free survival and overall survival were analyzed and compared according to tumor pathology. Moreover, the association between tumor control and the margin radiation dose to the tumor was analyzed, and the rate of tumor volume change after GKS was quantified. A total of 10 patients were enrolled in this study. Of these, 5 patients underwent a total of 8 sessions of GKS for chordoma, and the other 5 patients underwent a total of 7 sessions of GKS for chondrosarcoma. The 2- and 5-year progression-free survival rates for patients in the chordoma group were 70% and 35%, respectively, and rates for patients in the chondrosarcoma group were 100% and 80%, respectively (log-rank test, p = 0.04). The 2- and 5-year overall survival rates after GKS for patients in the chordoma group were 87.5% and 72.9%, respectively, and rates for patients in the chondrosarcoma group were 100% and 100%, respectively (log-rank test, p = 0.03). The mean rates of tumor volume change 2 years after radiosurgery were 79.64% and 39.91% for chordoma and

Gamma knife treatment for refractory epilepsy in seizure focus localized by positron emission tomography/CT★

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Bai, Xia; Wang, Xuemei; Wang, Hongwei; Zhao, Shigang; Han, Xiaodong; Hao, Linjun; Wang, Xiangcheng

2012-01-01

A total of 80 patients with refractory epilepsy were recruited from the Inner Mongolia Medical College Affiliated Hospital. The foci of 60% of the patients could be positioned using a combined positron emission tomography/CT imaging modality. Hyper- and hypometabolism foci were examined as part of this study. Patients who had abnormal metabolism in positron emission tomography/CT imaging were divided into intermittent-phase group and the seizure-phase group. The intermittent-phase group was further divided into a single-focus group and a multiple-foci group according to the number of seizure foci detected by imaging. Following gamma knife treatment, seizure frequency was significantly lower in the intermittent-phase group and the seizure-phase group. Wieser’s classification reached Grade I or II in nearly 40% of patients. Seizure frequency was significantly lower following treatment, but Wieser’s classification score was significantly higher in the seizure-phase group compared with the intermittent-phase group. Seizure frequency was significantly lower following treatment in the single-focus group, but Wieser’s classification score was significantly higher in the single-focus group as compared with the multiple-foci group. PMID:25317147

Safety and efficacy of endovascular therapy and gamma knife surgery for brain arteriovenous malformations in China: Study protocol for an observational clinical trial.

Science.gov (United States)

Jin, Hengwei; Huo, Xiaochuan; Jiang, Yuhua; Li, Xiaolong; Li, Youxiang

2017-09-01

Brain arteriovenous malformations (BAVMs) are associated with high morbidity and mortality. The treatment of BAVM remains controversial. Microinvasive treatment, including endovascular therapy and gamma knife surgery, has been the first choice in many conditions. However, the overall clinical outcome of microinvasive treatment remains unknown and a prospective trial is needed. This is a prospective, non-randomized, and multicenter observational registry clinical trial to evaluate the safety and efficacy of microinvasive treatment for BAVMs. The study will require up to 400 patients in approximately 12 or more centers in China, followed for 2 years. Main subjects of this study are BAVM patients underwent endovascular therapy and/or gamma knife surgery. The trial will not affect the choice of treatment modality. The primary outcomes are perioperative complications (safety), and postoperative hemorrhage incidence rate and complete occlusion rate (efficacy). Secondary outcomes are elimination of hemorrhage risk factors (coexisting aneurysms and arteriovenous fistula), volume reduction and remission of symptoms. Safety and efficacy of endovascular therapy, gamma knife surgery, and various combination modes of the two modalities will be compared. Operative complications and outcomes at pretreatment, post-treatment, at discharge and at 3 months, 6 months and 2 years follow-up intervals will be analyzed using the modified Rankin Scale (mRS). The most confusion on BAVM treatment is whether to choose interventional therapy or medical therapy, and the choice of interventional therapy modes. This study will provide evidence for evaluating the safety and efficacy of microinvasive treatment in China, to characterize the microinvasive treatment strategy for BAVMs.

Stereotactic radiosurgery XX: ocular neuromyotonia in association with gamma knife radiosurgery

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McQuillan, Joe; Plowman, P Nicholas; MacDougall, Niall; Blackburn, Philip; Sabin, H Ian; Ali, Nadeem; Drake, William M

2015-01-01

Summary We report three patients who developed symptoms and signs of ocular neuromyotonia (ONM) 3–6 months after receiving gamma knife radiosurgery (GKS) for functioning pituitary tumours. All three patients were complex, requiring multi-modality therapy and all had received prior external irradiation to the sellar region. Although direct causality cannot be attributed, the timing of the development of the symptoms would suggest that the GKS played a contributory role in the development of this rare problem, which we suggest clinicians should be aware of as a potential complication. Learning points GKS can cause ONM, presenting as intermittent diplopia.ONM can occur quite rapidly after treatment with GKS.Treatment with carbamazepine is effective and improve patient's quality of life. PMID:26294961

The safety and efficacy of gamma knife surgery in management of glomus jugulare tumor

Science.gov (United States)

2010-01-01

Background Glomus jugulare is a slowly growing, locally destructive tumor located in the skull base with difficult surgical access. The operative approach is, complicated by the fact that lesions may be both intra and extradural with engulfment of critical neurovascular structures. The tumor is frequently highly vascular, thus tumor resection entails a great deal of morbidity and not infrequent mortality. At timeslarge residual tumors are left behind. To decrease the morbidity associated with surgical resection of glomus jugulare, gamma knife surgery (GKS) was performed as an alternative in 13 patients to evaluate its safety and efficacy. Methods A retrospective review of 13 residual or unresectable glomus jagulare treated with GKS between 2004 and 2008.. Of these, 11 patients underwent GKS as the primary management and one case each was treated for postoperative residual disease and postembolization. The radiosurgical dose to the tumor margin ranged between 12-15 Gy. Results Post- gamma knife surgery and during the follow-up period twelve patients demonstrated neurological stability while clinical improvement was achieved in 5 patients. One case developed transient partial 7th nerve palsy that responded to medical treatment. In all patients radiographic MRI follow-up was obtained, the tumor size decreased in two cases and remained stable (local tumor control) in eleven patients. Conclusions Gamma knife surgery provids tumor control with a lowering of risk of developing a new cranial nerve injury in early follow-up period. This procedure can be safely used as a primary management tool in patients with glomus jugulare tumors, or in patients with recurrent tumors in this location. If long-term results with GKS are equally effective it will emerge as a good alternative to surgical resection. PMID:20819207

Monte Carlo simulation of the Leksell Gamma KnifeTM: II. Effects of heterogeneous versus homogeneous media for stereotactic radiosurgery

International Nuclear Information System (INIS)

Moskvin, Vadim; Timmerman, Robert; DesRosiers, Colleen; Randall, Marcus; DesRosiers, Paul; Dittmer, Phil; Papiez, Lech

2004-01-01

The absence of electronic equilibrium in the vicinity of bone-tissue or air-tissue heterogeneity in the head can misrepresent deposited dose with treatment planning algorithms that assume all treatment volume as homogeneous media. In this paper, Monte Carlo simulation (PENELOPE) and measurements with a specially designed heterogeneous phantom were applied to investigate the effect of air-tissue and bone-tissue heterogeneity on dose perturbation with the Leksell Gamma Knife TM . The dose fall-off near the air-tissue interface caused by secondary electron disequilibrium leads to overestimation of dose by the vendor supplied treatment planning software (GammaPlan TM ) at up to 4 mm from an interface. The dose delivered to the target area away from an air-tissue interface may be underestimated by up to 7% by GammaPlan TM due to overestimation of attenuation of photon beams passing through air cavities. While the underdosing near the air-tissue interface cannot be eliminated with any plug pattern, the overdosage due to under-attenuation of the photon beams in air cavities can be eliminated by plugging the sources whose beams intersect the air cavity. Little perturbation was observed next to bone-tissue interfaces. Monte Carlo results were confirmed by measurements. This study shows that the employed Monte Carlo treatment planning is more accurate for precise dosimetry of stereotactic radiosurgery with the Leksell Gamma Knife TM for targets in the vicinity of air-filled cavities

Stereotactic radiosurgery using the gamma knife for acoustic neuromas

International Nuclear Information System (INIS)

Foote, Robert L.; Coffey, Robert J.; Swanson, Jerry W.; Harner, Stephen G.; Beatty, Charles W.; Kline, Robert W.; Stevens, Lorna N.; Hu, Theresa C.

1995-01-01

Purpose: To assess the efficacy and toxicity of stereotactic radiosurgery using the gamma knife for acoustic neuromas. Methods and Materials: Between January 1990 and January 1993, 36 patients with acoustic neuromas were treated with stereotactic radiosurgery using the gamma knife. The median maximum tumor diameter was 21 mm (range: 6-32 mm). Tumor volumes encompassed within the prescribed isodose line varied from 266 to 8,667 mm 3 (median: 3,135 mm 3 ). Tumors ≤ 20 mm in maximum diameter received a dose of 20 Gy to the margin, tumors between 21 and 30 mm received 18 Gy, and tumors > 30 mm received 16 Gy. The dose was prescribed to the 50% isodose line in 31 patients and to the 45%, 55%, 60%, 70%, and 80% isodose line in one patient each. The median number of isocenters per tumor was 5 (range: 1-12). Results: At a median follow-up of 16 months (range: 2.5-36 months), all patients were alive. Thirty-five patients had follow-up imaging studies. Nine tumors (26%) were smaller, and 26 tumors (74%) were unchanged. No tumor had progressed. The 1- and 2-year actuarial incidences of facial neuropathy were 52.2% and 66.5%, respectively. The 1- and 2-year actuarial incidences of trigeminal neuropathy were 33.7% and 58.9%, respectively. The 1- and 2-year actuarial incidence of facial or trigeminal neuropathy (or both) was 60.8% and 81.7%, respectively. Multivariate analysis revealed that the following were associated with the time of onset or worsening of facial weakness or trigeminal neuropathy: (a) patients five isocenters. The 1- and 2-year actuarial rates of preservation of useful hearing (Gardner-Robertson class I or II) were 100% and 41.7% ± 17.3, respectively. Conclusion: Stereotactic radiosurgery using the gamma knife provides short-term control of acoustic neuromas when a dose of 16 to 20 Gy to the tumor margin is used. Preservation of useful hearing can be accomplished in a significant proportion of patients

SU-E-T-382: Evaluation of Clinical Application and Dosimetric Comparison for Treatment Plans of Gamma Knife and CyberKnife for Arteriovenous Malformations

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Kuo, C [Department of Radiation Oncology, Shuang Ho Hospital, Taipei Medical Univer, New Taipei City, Taiwan (R.O.C.) (China)

2015-06-15

Purpose: To analyze and compare the characteristics of dose distributions between Gamma Knife (GK) and CyberKnife (CK), in treating arteriovenous malformations (AVMs), and evaluate the influences on their clinical applications. Methods: Twenty four patients with AVMs treated with CK of prescribed dose (PD) of 16–25 Gy in single fraction were selected. Each patient’s CT images used for CK treatment planning with contours of targets and critical organs were exported and then loaded into the GK planning system. GK treatment plan with the same PD used in CK was generated for each patient. The metrics for dose comparison between GK and CK included conformity index (CI), gradient index (GI) of 75%, 50% and 25% of the PD, heterogeneity index (HI), volume of brain tissues covered by 10 Gy and 12 Gy, maximum dose to brainstem and beam-on time. Paired Samples t-test was used to analyze these metrics for significance (p value). Results: The CI were 0.744 ± 0.075 (GK) and 0.768 ± 0.086 (CK), p = 0.281. The GI75%, GI50%, and GI25% in GK and CK were 1.735 ± 0.100 and 2.439 ± 0.338 (p < 0.001), 3.169 ± 0.265 and 4.972 ± 0.852 (p < 0.001), and 8.650 ± 0.914 and 14.261 ± 2.476 (p < 0.001). The HI were 0.728 ± 0.072 (GK) and 0.313 ± 0.069 (CK), p < 0.001. There were significant differences both for volume of brain tissues covered by 10 Gy and 12 Gy in GK and CK (p < 0.001). GK had smaller maximum dose to brainstem. CK had shorter beam-on time. Conclusion: GK has similar dose conformity as CK, and has better normal tissue sparing but is less efficient than CK.

SU-E-T-382: Evaluation of Clinical Application and Dosimetric Comparison for Treatment Plans of Gamma Knife and CyberKnife for Arteriovenous Malformations

International Nuclear Information System (INIS)

Kuo, C

2015-01-01

Purpose: To analyze and compare the characteristics of dose distributions between Gamma Knife (GK) and CyberKnife (CK), in treating arteriovenous malformations (AVMs), and evaluate the influences on their clinical applications. Methods: Twenty four patients with AVMs treated with CK of prescribed dose (PD) of 16–25 Gy in single fraction were selected. Each patient’s CT images used for CK treatment planning with contours of targets and critical organs were exported and then loaded into the GK planning system. GK treatment plan with the same PD used in CK was generated for each patient. The metrics for dose comparison between GK and CK included conformity index (CI), gradient index (GI) of 75%, 50% and 25% of the PD, heterogeneity index (HI), volume of brain tissues covered by 10 Gy and 12 Gy, maximum dose to brainstem and beam-on time. Paired Samples t-test was used to analyze these metrics for significance (p value). Results: The CI were 0.744 ± 0.075 (GK) and 0.768 ± 0.086 (CK), p = 0.281. The GI75%, GI50%, and GI25% in GK and CK were 1.735 ± 0.100 and 2.439 ± 0.338 (p < 0.001), 3.169 ± 0.265 and 4.972 ± 0.852 (p < 0.001), and 8.650 ± 0.914 and 14.261 ± 2.476 (p < 0.001). The HI were 0.728 ± 0.072 (GK) and 0.313 ± 0.069 (CK), p < 0.001. There were significant differences both for volume of brain tissues covered by 10 Gy and 12 Gy in GK and CK (p < 0.001). GK had smaller maximum dose to brainstem. CK had shorter beam-on time. Conclusion: GK has similar dose conformity as CK, and has better normal tissue sparing but is less efficient than CK

SU-F-P-15: Report On AAPM TG 178 Gamma Knife Dosimetry and Quality Assurance

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Goetsch, S [San Diego Medical Physics, Solana Beach, CA (United States)

2016-06-15

Purpose: AAPM Task Group 178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance was formed in August, 2008. The Task Group has 12 medical physicists, two physicians and two consultants. Methods: A round robin dosimetry intercomparison of proposed ionization chambers, electrometer and dosimetry phantoms was conducted over a 15 month period in 2011 and 2012 (Med Phys 42, 11, Nov, 2015). The data obtained at 9 institutions (with ten different Elekta Gamma Knife units) was analyzed by the lead author using several protocols. Results: The most consistent results were obtained using the Elekta ABS 16cm diameter phantom, with the TG-51 protocol modified as recommended by Alfonso et al (Med Phys 35, 11, Nov 2008). A key white paper (Med Phys, in press) sponsored by Elekta Corporation, was used to obtain correction factors for the ionization chambers and phantoms used in this intercomparison. Consistent results were obtained for both Elekta Gamma Knife Model 4C and Gamma Knife Perfexion units as measured with each of two miniature ionization chambers Conclusion: The full TG 178 report gives clinical history and background of gamma stereotactic radiosurgery, clinical examples and history, quality assurance recommendations and outline of possible dosimetry protocols. The report will be reviewed by the AAPM Working Group on Recommendations for Radiotherapy External Beam Quality Assurance and then by the AAPM Science Council before publication in Medical Physics. Consultant to Elekta, Inc.

SU-F-P-15: Report On AAPM TG 178 Gamma Knife Dosimetry and Quality Assurance

International Nuclear Information System (INIS)

Goetsch, S

2016-01-01

Purpose: AAPM Task Group 178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance was formed in August, 2008. The Task Group has 12 medical physicists, two physicians and two consultants. Methods: A round robin dosimetry intercomparison of proposed ionization chambers, electrometer and dosimetry phantoms was conducted over a 15 month period in 2011 and 2012 (Med Phys 42, 11, Nov, 2015). The data obtained at 9 institutions (with ten different Elekta Gamma Knife units) was analyzed by the lead author using several protocols. Results: The most consistent results were obtained using the Elekta ABS 16cm diameter phantom, with the TG-51 protocol modified as recommended by Alfonso et al (Med Phys 35, 11, Nov 2008). A key white paper (Med Phys, in press) sponsored by Elekta Corporation, was used to obtain correction factors for the ionization chambers and phantoms used in this intercomparison. Consistent results were obtained for both Elekta Gamma Knife Model 4C and Gamma Knife Perfexion units as measured with each of two miniature ionization chambers Conclusion: The full TG 178 report gives clinical history and background of gamma stereotactic radiosurgery, clinical examples and history, quality assurance recommendations and outline of possible dosimetry protocols. The report will be reviewed by the AAPM Working Group on Recommendations for Radiotherapy External Beam Quality Assurance and then by the AAPM Science Council before publication in Medical Physics. Consultant to Elekta, Inc

Endocrinologist's first experience in the treatment of pituitary adenomas using Leksell's gamma knife

International Nuclear Information System (INIS)

Marek, J.; Malik, J.; Fendrych, P.

1996-01-01

The group treated included 13 patients with pituitary adenomas. Hormonally active acromegaly was found in 9 patients, prolactinoma in 1 patient, and afunctional adenoma in 3 patients. Twelve patients had previously undergone surgery, 3 of them twice. Magnetic resonance was used for imaging the pituitary prior to the surgery and one year later. The following hormonal factors were examined: the growth hormone during the day and during the thyroliberin test, the insulin-like growth factor I, the prolactin level, the thyrotropin level during the thyrotropin-releasing hormone test, the thyroxine and triiodothyronine levels, the plasma concentration of adrenocorticotropin, the cortisol level, the plasma testosterone level, and the 17-beta estradiol level. Complete recovery within 18 months after the Leksell surgery was only achieved in 1 female patient with acromegaly. In other 5 patients with acromegaly and 1 patient with prolactinoma, the hormonal levels decreased partly without demonstrable changes in the size of the adenoma. Hypopituarism developed in 1 only female patient within 18 months after the irradiation. No other complications were observed. Stereotactic irradiation with Leksell's gamma knife proved to be a useful and well tolerated approach in the treatment of pituitary adenomas. 11 refs

Quality of life after gamma knife radiosurgery treatment in patients with a vestibular schwannoma: the patient’s perspective

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van Haren, Anniek E. P.; Mulder, Jef J. S.; Hanssens, Patrick E. J.; van Overbeeke, Jacobus J.; Cremers, Cor W. R. J.; Graamans, Kees

2009-01-01

This study evaluates the impact of gamma knife radiosurgery (GKRS) on the quality of life (QOL) of patients with a sporadic vestibular schwannoma (VS). This study pertains to 108 VS patients who had GKRS in the years 2003 through 2007. Two different QOL questionnaires were used: medical outcome study short form 36 (SF36) and Glasgow benefit inventory (GBI). Radiosurgery was performed using a Leksell 4C gamma knife. The results of the QOL questionnaires in relation to prospectively and retrospectively gathered data of the VS patients treated by GKRS. Eventually, 97 patients could be included in the study. Their mean tumor size was 17 mm (range 6–39 mm); the mean maximum dose on the tumor was 19.9 Gy (range 16–25.5 Gy) and the mean marginal dose on the tumor was 11.1 (range 9.3–12.5 Gy). SF36 scores showed results comparable to those for a normal Dutch population. GBI showed a marginal decline in QOL. No correlation was found between QOL and gender, age, tumor size, or radiation dose. Increased audiovestibular symptoms after GKRS were correlated with a decreased GBI score, and decreased symptoms were correlated with a higher QOL post-GKRS. In this study shows that GKRS for VS has little impact on the general QOL of the VS patient. However, there is a wide range in individual QOL results. Individual QOL was influenced by the audiovestibular symptoms. No predictive patient, tumor, or treatment factors for QOL outcome after GKRS could be determined. Comparison with microsurgery is difficult because of intra group variability. PMID:19894058

Vestibular schwannomas: clinical results and quality of life after microsurgery or gamma knife radiosurgery.

Science.gov (United States)

Myrseth, Erling; Møller, Per; Pedersen, Paal-Henning; Vassbotn, Flemming S; Wentzel-Larsen, Tore; Lund-Johansen, Morten

2005-05-01

The aim of the present study was to evaluate the overall treatment efficacy (tumor control, facial nerve function, complications) and quality of life for patients treated primarily for unilateral vestibular schwannomas of 30 mm or less, either by microsurgery or by gamma knife (GK) radiosurgery. The results for the two treatment groups are compared with each other, with main emphasis on the long-term quality of life. This is a retrospective study of 189 consecutive patients, 86 treated by microsurgery and 103 by gamma knife. The mean observation time was 5.9 years. All patients had a magnetic resonance imaging scan and clinical evaluation performed toward the end of the study. To evaluate the quality of life, we used two standardized questionnaires, the Glasgow Benefit Inventory and Short-Form 36. The questionnaires were sent to the 168 living patients. The reply rate was 83.3%. A total of 79.8% of the patients in the microsurgery group and 94.8% of the GK patients had a good facial nerve function (House-Brackmann Grade 1-2). Hearing was usually lost after microsurgery, whereas the GK patients had preserved hearing, which often became reduced over the years after the treatment. The treatment efficacy, defined as no need for additional treatment, was similar for the two treatment modalities. Quality of life was reduced compared with normative data, being most reduced in the microsurgery group. Some of the quality of life questions showed an association with facial nerve function and sex. Posttreatment facial nerve function, hearing, complication rates, and quality of life were all significantly in favor of GK radiosurgery.

In vitro study of dose rate effect on Leksell Gamma Knife Perfexion

International Nuclear Information System (INIS)

Pastykova, V.; Novotny, J. jr.; Vachelova, J.; Davidkova, M.; Liscak, R.

2018-01-01

The main purpose of the study is to evaluate the radiobiological effect of the dose rate changes in Leksell Gamma Knife (LGK) clinical conditions. In principle there are two reasons why dose rate on LGK is reduced during patient irradiation: 1) Co-60 sources decay with a half-life of 5.26 years and 2) using multiple iso-centers and conformal treatment plans (e.g. with blocked beams). This pilot study is an experimental work performed in vitro with medulloblastoma DAOY cells. Are there effects caused by low dose rate which could negatively influence the clinical outcome of the radiosurgery? (authors)

Peripheral dose measurement for CyberKnife radiosurgery with upgraded linac shielding

International Nuclear Information System (INIS)

Chuang, Cynthia F.; Larson, David A.; Zytkovicz, Andrea; Smith, Vernon; Petti, Paula L.

2008-01-01

The authors investigated the peripheral dose reduction for CyberKnife radiosurgery treatments after the installation of a linac shielding upgrade. As in a previous investigation, the authors considered two treatment plans, one for a hypothetical target in the brain and another for a target in the thorax, delivered to an anthropomorphic phantom. The results of the prior investigation showed that the CyberKnife delivered significantly higher peripheral doses than comparable model C Gamma Knife or IMRT treatments. Current measurements, after the linac shielding upgrade, demonstrate that the additional shielding decreased the peripheral dose, expressed as a percentage of the delivered monitor units (MU), by a maximum of 59%. The dose reduction was greatest for cranial-caudal distances from the field edge less than 30 cm, and at these distances, the CyberKnife peripheral dose, expressed as a percentage of the delivered MU, is now comparable to that measured for the other treatment modalities in our previous investigation. For distances between 30 and 70 cm from the field edge, the additional shielding reduced the peripheral dose by between 20% and 55%. At these distances, the CyberKnife peripheral dose remains higher than doses measured in our previous study for the model C Gamma Knife and IMRT

Repeat Gamma-Knife Radiosurgery for Refractory or Recurrent Trigeminal Neuralgia with Consideration About the Optimal Second Dose.

Science.gov (United States)

Park, Seong-Cheol; Kwon, Do Hoon; Lee, Do Hee; Lee, Jung Kyo

2016-02-01

To investigate adequate radiation doses for repeat Gamma Knife radiosurgery (GKS) for trigeminal neuralgia in our series and meta-analysis. Fourteen patients treated by ipsilateral repeat GKS for trigeminal neuralgia were included. Median age of patients was 65 years (range, 28-78), the median target dose, 140-180). Patients were followed a median of 10.8 months (range, 1-151) after the second gamma-knife surgery. Brainstem dose analysis and vote-counting meta-analysis of 19 studies were performed. After the second gamma-knife radiosurgeries, pain was relieved effectively in 12 patients (86%; Barrow Neurological Institute Pain Intensity Score I-III). Post-gamma-knife radiosurgery trigeminal nerve deficits were mild in 5 patients. No serious anesthesia dolorosa was occurred. The second GKS radiation dose ≤ 60 Gy was significantly associated with worse pain control outcome (P = 0.018 in our series, permutation analysis of variance, and P = 0.009 in the meta-analysis, 2-tailed Fisher's exact test). Cumulative dose ≤ 140-150 Gy was significantly associated with poor pain control outcome (P = 0.033 in our series and P = 0.013 in the meta-analysis, 2-tailed Fisher's exact test). A cumulative brainstem edge dose >12 Gy tended to be associated with trigeminal nerve deficit (P = 0.077). Our study suggests that the second GKS dose is a potentially important factor. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of bone- and air-tissue inhomogeneities on the dose distributions of the Leksell Gamma Knife (registered) calculated with PENELOPE

International Nuclear Information System (INIS)

Al-Dweri, Feras M O; Rojas, E Leticia; Lallena, Antonio M

2005-01-01

Monte Carlo simulation with PENELOPE (version 2003) is applied to calculate Leksell Gamma Knife (registered) dose distributions for heterogeneous phantoms. The usual spherical water phantom is modified with a spherical bone shell simulating the skull and an air-filled cube simulating the frontal or maxillary sinuses. Different simulations of the 201 source configuration of the Gamma Knife have been carried out with a simplified model of the geometry of the source channel of the Gamma Knife recently tested for both single source and multisource configurations. The dose distributions determined for heterogeneous phantoms including the bone- and/or air-tissue interfaces show non-negligible differences with respect to those calculated for a homogeneous one, mainly when the Gamma Knife isocentre approaches the separation surfaces. Our findings confirm an important underdosage (∼10%) nearby the air-tissue interface, in accordance with previous results obtained with the PENELOPE code with a procedure different from ours. On the other hand, the presence of the spherical shell simulating the skull produces a few per cent underdosage at the isocentre wherever it is situated

Results of Gamma Knife Radiosurgery in Acromegaly

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Alberto Franzin

2012-01-01

Full Text Available Objective. Single-session radiosurgery with Gamma Knife (GK may be a potential adjuvant treatment in acromegaly. We analyzed the safety and efficacy of GK in patients who had previously received maximal surgical debulking at our hospital. Methods. The study was a retrospective analysis of hormonal, radiological, and ophthalmologic data collected in a predefined protocol from 1994 to 2009. The mean age at treatment was 42.3 years (range 22–67 yy. 103 acromegalic patients participated in the study. The median follow-up was 71 months (IQ range 43–107. All patients were treated with GK for residual or recurrent GH-secreting adenoma. Results. Sixty-three patients (61.2% reached the main outcome of the study. The rate of remission was 58.3% at 5 years (95% CI 47.6–69.0%. Other 15 patients (14.6% were in remission after GK while on treatment with somatostatin analogues. No serious side effects occurred after GK. Eight patients (7.8% experienced a new deficit of pituitary function. New cases of hypogonadism, hypothyroidism, and hypoadrenalism occurred in 4 of 77 patients (5.2%, 3 of 95 patients (3.2%, and 6 of 100 patients at risk (6.0%, respectively. Conclusion. In a highly selected group of acromegalic patients, GK treatment had good efficacy and safety.

Automated gamma knife radiosurgery treatment planning with image registration, data-mining, and Nelder-Mead simplex optimization

International Nuclear Information System (INIS)

Lee, Kuan J.; Barber, David C.; Walton, Lee

2006-01-01

Gamma knife treatments are usually planned manually, requiring much expertise and time. We describe a new, fully automatic method of treatment planning. The treatment volume to be planned is first compared with a database of past treatments to find volumes closely matching in size and shape. The treatment parameters of the closest matches are used as starting points for the new treatment plan. Further optimization is performed with the Nelder-Mead simplex method: the coordinates and weight of the isocenters are allowed to vary until a maximally conformal plan specific to the new treatment volume is found. The method was tested on a randomly selected set of 10 acoustic neuromas and 10 meningiomas. Typically, matching a new volume took under 30 seconds. The time for simplex optimization, on a 3 GHz Xeon processor, ranged from under a minute for small volumes ( 30 000 cubic mm,>20 isocenters). In 8/10 acoustic neuromas and 8/10 meningiomas, the automatic method found plans with conformation number equal or better than that of the manual plan. In 4/10 acoustic neuromas and 5/10 meningiomas, both overtreatment and undertreatment ratios were equal or better in automated plans. In conclusion, data-mining of past treatments can be used to derive starting parameters for treatment planning. These parameters can then be computer optimized to give good plans automatically

GammaKnife surgery: safety and the identity of users.

Science.gov (United States)

Dinka, David; Nyce, James M; Timpka, Toomas

2005-01-01

In this study we investigated safety-related usability issues of an advanced medical technology, a radiosurgery system. We were interested in which criteria are important for users when a system's usability and safety is to be improved. The data collection was based on interviews and observations at three different sites where the Leksell GammaKnife is used. The analysis was qualitative. The main finding was that the user's identity or professional background has a significant impact both on how he or she views his or her role in the clinical setting, and on how he or she defines what improvements are necessary and general safety issues. In fact, the opinion even of users experienced in safety-related problems was highly influenced by how they related to the technology and its development. None of the users actually considered Leksell GammaKnife as lacking in safety, instead, their assessment was directed towards potential future system improvements. Our findings suggest that the importance of user identity or professional background cannot be neglected during the development of advanced technology. They also suggest that the user feedback should always be related to user background and identity in order to understand how important different issues are for particular users.

Monte Carlo simulation of the Leksell Gamma Knife{sup TM}: II. Effects of heterogeneous versus homogeneous media for stereotactic radiosurgery

Energy Technology Data Exchange (ETDEWEB)

Moskvin, Vadim; Timmerman, Robert; DesRosiers, Colleen; Randall, Marcus; DesRosiers, Paul; Dittmer, Phil; Papiez, Lech [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, 535 Barnhill Dr, RT041, IN 46202-5289 (United States)

2004-11-07

The absence of electronic equilibrium in the vicinity of bone-tissue or air-tissue heterogeneity in the head can misrepresent deposited dose with treatment planning algorithms that assume all treatment volume as homogeneous media. In this paper, Monte Carlo simulation (PENELOPE) and measurements with a specially designed heterogeneous phantom were applied to investigate the effect of air-tissue and bone-tissue heterogeneity on dose perturbation with the Leksell Gamma Knife{sup TM}. The dose fall-off near the air-tissue interface caused by secondary electron disequilibrium leads to overestimation of dose by the vendor supplied treatment planning software (GammaPlan{sup TM}) at up to 4 mm from an interface. The dose delivered to the target area away from an air-tissue interface may be underestimated by up to 7% by GammaPlan{sup TM} due to overestimation of attenuation of photon beams passing through air cavities. While the underdosing near the air-tissue interface cannot be eliminated with any plug pattern, the overdosage due to under-attenuation of the photon beams in air cavities can be eliminated by plugging the sources whose beams intersect the air cavity. Little perturbation was observed next to bone-tissue interfaces. Monte Carlo results were confirmed by measurements. This study shows that the employed Monte Carlo treatment planning is more accurate for precise dosimetry of stereotactic radiosurgery with the Leksell Gamma Knife{sup TM} for targets in the vicinity of air-filled cavities.

Technical note: A 3D-printed phantom for routine accuracy check of Gamma Knife Icon HDMM system.

Science.gov (United States)

Wu, Chuan; Radevic, Marlyn B; Glass, Jennifer S; Skubic, Stan E

2018-05-23

To report a novel 3D-printed device ("SH phantom") that is designed for routine accuracy check of the Gamma Knife Icon High Definition Motion Management (HDMM) system. SH phantom was designed using tinkerCAD software and printed on a commercial 3D printer. We evaluated the SH phantom on our Gamma Knife Icon unit regarding its usability and accuracy for routine HDMM QA. Single-axis and multiple-axis measurements validated the SH phantom design and implementation. An HDMM QA accuracy of 0.22 mm or better along single axis was found using SH phantom. The SH phantom proved to be a quick and simple tool to use to perform the HDMM system QA. The SH phantom was tested successfully and adopted by us as part of monthly QA for the Gamma Knife Icon. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Die Behandlung des Akustikusneurinoms mit dem Gamma-Knife

OpenAIRE

Hempel, Elizabeta

2005-01-01

Das Akustikusneurinom ist mit ca. 6% der häufigste intrakranielle Tumor und hat eine jährliche Inzidenz von 1:100000. Die durchschnittliche Wachstumsrate beträgt 2 mm pro Jahr, wobei es auch Akustikusneurinome gibt, die sehr viel schneller wachsen können. Bei der Behandlung des Schwannoms stehen uns zwei Modalitäten zur Verfügung. Die konventionelle Chirurgie und die stereotaktische Radiochirurgie, zu der die Gamma-Knife Therapie und der Linearbeschleuniger zählen. Sorgfältig ausgesuchte P...

Gamma knife radiosurgery of acoustic neurinomas

International Nuclear Information System (INIS)

Bertalanffy, A.; Dietrich, W.; Aichholzer, M.; Kitz, K.; Heimberger, K.; Brix, R.

2001-01-01

The authors report on their series of 40 patients with 41 acoustic neurinomas (ACNs), including one patient with bilateral acoustic neurinomas suffering from neurofibromatosis type 2 (NF II) who were treated with the gamma knife unit at their institution between August 1992 and October 1995. Of these 41 tumours, 21 ACNs had been operated on before (l to 4 times), 20 ACNs were exclusively treated by gamma knife radiosurgery (GKRS). The maximal axial tumour diameter ranged from 6 to 33 mm (median: 25 mm), the maximal transverse tumour diameter ranged from 7 mm to 36 mm (median: 16 mm). The dose distributed to the tumour margin was 10 to 17 Gy (median: 12 Gy) by enclosing the tumour with the 40 % to 95 % isodose line (median: 50 % isodose line) and using 1 to 12 isocenters (median: 5 isocenters). Central loss of contrast enhancement was observed in 78 % of the patients within six to 12 months after radiosurgery. Thirty-two patients were observed over a minimum follow up period of at least 36 months, 9 patients were lost to follow up as they died of unrelated causes or refused further check-ups. Within the follow up period of up to seven years, magnetic resonance imaging (MRI) control scans revealed the tumour diameter stable or decreased in 29 cases and increased in three tumours. Of 14 patients with useful hearing before treatment, 9 patients were examined in addition to pure tone audiogramm by measurement of brainstem auditory evoked potentials (BAEPs) one to four years after radiosurgery. None of three patients showed a postoperative loss of the cochlea function. According to slight alterations of the cochlea function (cochlea summating action potential), pure tone audiometry of those patients revealed only slight changes of the hearing level (HL) within a maximum range of ±15 Decibel (dB). The hearing threshold improved in two, was stable in four and deteriorated in three patients, respectively. We observed postradiosurgical aggravation of a pre-existing facial

Gamma knife radiosurgery of acoustic neurinomas

Energy Technology Data Exchange (ETDEWEB)

Bertalanffy, A; Dietrich, W; Aichholzer, M; Kitz, K [Department of Neurosurgery, University of Vienna, Medical School, Vienna (Austria); Heimberger, K [Department of Radiology, Division: Neuroradiology, University of Vienna, Medical School, Vienna (Austria); Brix, R [Department of Otorhinolaryngology, University of Vienna, Medical School, Vienna (Austria)

2001-07-01

The authors report on their series of 40 patients with 41 acoustic neurinomas (ACNs), including one patient with bilateral acoustic neurinomas suffering from neurofibromatosis type 2 (NF II) who were treated with the gamma knife unit at their institution between August 1992 and October 1995. Of these 41 tumours, 21 ACNs had been operated on before (l to 4 times), 20 ACNs were exclusively treated by gamma knife radiosurgery (GKRS). The maximal axial tumour diameter ranged from 6 to 33 mm (median: 25 mm), the maximal transverse tumour diameter ranged from 7 mm to 36 mm (median: 16 mm). The dose distributed to the tumour margin was 10 to 17 Gy (median: 12 Gy) by enclosing the tumour with the 40 % to 95 % isodose line (median: 50 % isodose line) and using 1 to 12 isocenters (median: 5 isocenters). Central loss of contrast enhancement was observed in 78 % of the patients within six to 12 months after radiosurgery. Thirty-two patients were observed over a minimum follow up period of at least 36 months, 9 patients were lost to follow up as they died of unrelated causes or refused further check-ups. Within the follow up period of up to seven years, magnetic resonance imaging (MRI) control scans revealed the tumour diameter stable or decreased in 29 cases and increased in three tumours. Of 14 patients with useful hearing before treatment, 9 patients were examined in addition to pure tone audiogramm by measurement of brainstem auditory evoked potentials (BAEPs) one to four years after radiosurgery. None of three patients showed a postoperative loss of the cochlea function. According to slight alterations of the cochlea function (cochlea summating action potential), pure tone audiometry of those patients revealed only slight changes of the hearing level (HL) within a maximum range of {+-}15 Decibel (dB). The hearing threshold improved in two, was stable in four and deteriorated in three patients, respectively. We observed postradiosurgical aggravation of a pre-existing facial

Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber.

Science.gov (United States)

Hršak, Hrvoje; Majer, Marija; Grego, Timor; Bibić, Juraj; Heinrich, Zdravko

2014-12-01

Dosimetry for Gamma-Knife requires detectors with high spatial resolution and minimal angular dependence of response. Angular dependence and end effect time for p-type silicon detectors (PTW Diode P and Diode E) and PTW PinPoint ionization chamber were measured with Gamma-Knife beams. Weighted angular dependence correction factors were calculated for each detector. The Gamma-Knife output factors were corrected for angular dependence and end effect time. For Gamma-Knife beams angle range of 84°-54°. Diode P shows considerable angular dependence of 9% and 8% for the 18 mm and 14, 8, 4 mm collimator, respectively. For Diode E this dependence is about 4% for all collimators. PinPoint ionization chamber shows angular dependence of less than 3% for 18, 14 and 8 mm helmet and 10% for 4 mm collimator due to volumetric averaging effect in a small photon beam. Corrected output factors for 14 mm helmet are in very good agreement (within ±0.3%) with published data and values recommended by vendor (Elekta AB, Stockholm, Sweden). For the 8 mm collimator diodes are still in good agreement with recommended values (within ±0.6%), while PinPoint gives 3% less value. For the 4 mm helmet Diodes P and E show over-response of 2.8% and 1.8%, respectively. For PinPoint chamber output factor of 4 mm collimator is 25% lower than Elekta value which is generally not consequence of angular dependence, but of volumetric averaging effect and lack of lateral electronic equilibrium. Diodes P and E represent good choice for Gamma-Knife dosimetry. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Gamma knife radiosurgery for acoustic Schwannoma. Early effects and preservation of hearing

Energy Technology Data Exchange (ETDEWEB)

Hirato, Masafumi; Inoue, Hiroshi; Nakamura, Masaru; Ohye, Chihiro; Hirato, Junko [Gunma Univ., Maebashi (Japan). School of Medicine; Shibazaki, Tohru; Andou, Yoshitaka

1995-10-01

The effects of relatively low dose gamma knife irradiation on acoustic Schwannoma were evaluated. The signal intensity change and tumor shrinkage on magnetic resonance (MR) images, change in hearing, and complications in 28 patients (mean age 47.0{+-}13.6 yrs) were studied. Three patients had bilateral tumors. Six were already deaf when treated. The maximum tumor diameter was 35 mm. The mean dose delivered to the tumor was 12.1{+-}1.6 Gy at the periphery, and 25.2{+-}4.3 Gy at the center. The mean follow-up time was 16 months and the longest 24 months. Lowering of the MR signal intensity in the tumor center appeared after 3 months at earliest but generally after 6 months. Signs of tumor shrinkage appeared within 12 months on average. Cyst in the tumor enlarged rapidly after treatment in two patients. The percentage of hearing preservation was 85% (17/20) at 3 months, 80% (16/20) at 6 months, 72% (13/18) at 9 months, 75% (12/16) at 12 months, 67% (8/12) at 15 months, 60% (6/10) at 18 months, and 50% (2/4) at 24 months. Subtle changes in hearing were detected by speech tone audiometry. Temporary facial numbness and weakness was seen in one patient each. No patient had lower cranial nerve paresis. Relatively low dose gamma knife radiosurgery is effective in suppressing growth of acoustic Schwannoma with preservation of hearing. (author).

Gamma knife radiosurgery for acoustic Schwannoma. Early effects and preservation of hearing

International Nuclear Information System (INIS)

Hirato, Masafumi; Inoue, Hiroshi; Nakamura, Masaru; Ohye, Chihiro; Hirato, Junko; Shibazaki, Tohru; Andou, Yoshitaka.

1995-01-01

The effects of relatively low dose gamma knife irradiation on acoustic Schwannoma were evaluated. The signal intensity change and tumor shrinkage on magnetic resonance (MR) images, change in hearing, and complications in 28 patients (mean age 47.0±13.6 yrs) were studied. Three patients had bilateral tumors. Six were already deaf when treated. The maximum tumor diameter was 35 mm. The mean dose delivered to the tumor was 12.1±1.6 Gy at the periphery, and 25.2±4.3 Gy at the center. The mean follow-up time was 16 months and the longest 24 months. Lowering of the MR signal intensity in the tumor center appeared after 3 months at earliest but generally after 6 months. Signs of tumor shrinkage appeared within 12 months on average. Cyst in the tumor enlarged rapidly after treatment in two patients. The percentage of hearing preservation was 85% (17/20) at 3 months, 80% (16/20) at 6 months, 72% (13/18) at 9 months, 75% (12/16) at 12 months, 67% (8/12) at 15 months, 60% (6/10) at 18 months, and 50% (2/4) at 24 months. Subtle changes in hearing were detected by speech tone audiometry. Temporary facial numbness and weakness was seen in one patient each. No patient had lower cranial nerve paresis. Relatively low dose gamma knife radiosurgery is effective in suppressing growth of acoustic Schwannoma with preservation of hearing. (author)

Gamma Knife Radiosurgery for the Treatment of Cystic Cerebral Metastases

Energy Technology Data Exchange (ETDEWEB)

Ebinu, Julius O.; Lwu, Shelly; Monsalves, Eric; Arayee, Mandana [Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, Toronto, Ontario (Canada); Chung, Caroline; Laperriere, Normand J. [Department of Radiation Oncology, Princess Margaret Hospital, University Health Network, University of Toronto, Toronto, Ontario (Canada); Kulkarni, Abhaya V.; Goetz, Pablo [Division of Neurosurgery, Department of Surgery, The Hospital for Sick Children, University of Toronto, Toronto, Ontario (Canada); Zadeh, Gelareh, E-mail: gelareh.zadeh@uhn.on.ca [Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, Toronto, Ontario (Canada)

2013-03-01

Purpose: To assess the role of Gamma Knife radiosurgery (GKRS) in the treatment of nonsurgical cystic brain metastasis, and to determine predictors of response to GKRS. Methods: We reviewed a prospectively maintained database of brain metastases patients treated at our institution between 2006 and 2010. All lesions with a cystic component were identified, and volumetric analysis was done to measure percentage of cystic volume on day of treatment and consecutive follow-up MRI scans. Clinical, radiologic, and dosimetry parameters were reviewed to establish the overall response of cystic metastases to GKRS as well as identify potential predictive factors of response. Results: A total of 111 lesions in 73 patients were analyzed; 57% of lesions received prior whole-brain radiation therapy (WBRT). Lung carcinoma was the primary cancer in 51% of patients, 10% breast, 10% colorectal, 4% melanoma, and 26% other. Fifty-seven percent of the patients were recursive partitioning analysis class 1, the remainder class 2. Mean target volume was 3.3 mL (range, 0.1-23 mL). Median prescription dose was 21 Gy (range, 15-24 Gy). Local control rates were 91%, 63%, and 37% at 6, 12, and 18 months, respectively. Local control was improved in lung primary and worse in patients with prior WBRT (univariate). Only lung primary predicted local control in multivariate analysis, whereas age and tumor volume did not. Lesions with a large cystic component did not show a poorer response compared with those with a small cystic component. Conclusions: This study supports the use of GKRS in the management of nonsurgical cystic metastases, despite a traditionally perceived poorer response. Our local control rates are comparable to a matched cohort of noncystic brain metastases, and therefore the presence of a large cystic component should not deter the use of GKRS. Predictors of response included tumor subtype. Prior WBRT decreased effectiveness of SRS for local control rates.

Gamma Knife Radiosurgery for the Treatment of Cystic Cerebral Metastases

International Nuclear Information System (INIS)

Ebinu, Julius O.; Lwu, Shelly; Monsalves, Eric; Arayee, Mandana; Chung, Caroline; Laperriere, Normand J.; Kulkarni, Abhaya V.; Goetz, Pablo; Zadeh, Gelareh

2013-01-01

Purpose: To assess the role of Gamma Knife radiosurgery (GKRS) in the treatment of nonsurgical cystic brain metastasis, and to determine predictors of response to GKRS. Methods: We reviewed a prospectively maintained database of brain metastases patients treated at our institution between 2006 and 2010. All lesions with a cystic component were identified, and volumetric analysis was done to measure percentage of cystic volume on day of treatment and consecutive follow-up MRI scans. Clinical, radiologic, and dosimetry parameters were reviewed to establish the overall response of cystic metastases to GKRS as well as identify potential predictive factors of response. Results: A total of 111 lesions in 73 patients were analyzed; 57% of lesions received prior whole-brain radiation therapy (WBRT). Lung carcinoma was the primary cancer in 51% of patients, 10% breast, 10% colorectal, 4% melanoma, and 26% other. Fifty-seven percent of the patients were recursive partitioning analysis class 1, the remainder class 2. Mean target volume was 3.3 mL (range, 0.1-23 mL). Median prescription dose was 21 Gy (range, 15-24 Gy). Local control rates were 91%, 63%, and 37% at 6, 12, and 18 months, respectively. Local control was improved in lung primary and worse in patients with prior WBRT (univariate). Only lung primary predicted local control in multivariate analysis, whereas age and tumor volume did not. Lesions with a large cystic component did not show a poorer response compared with those with a small cystic component. Conclusions: This study supports the use of GKRS in the management of nonsurgical cystic metastases, despite a traditionally perceived poorer response. Our local control rates are comparable to a matched cohort of noncystic brain metastases, and therefore the presence of a large cystic component should not deter the use of GKRS. Predictors of response included tumor subtype. Prior WBRT decreased effectiveness of SRS for local control rates

Evaluation of stability of stereotactic space defined by cone-beam CT for the Leksell Gamma Knife Icon.

Science.gov (United States)

AlDahlawi, Ismail; Prasad, Dheerendra; Podgorsak, Matthew B

2017-05-01

The Gamma Knife Icon comes with an integrated cone-beam CT (CBCT) for image-guided stereotactic treatment deliveries. The CBCT can be used for defining the Leksell stereotactic space using imaging without the need for the traditional invasive frame system, and this allows also for frameless thermoplastic mask stereotactic treatments (single or fractionated) with the Gamma Knife unit. In this study, we used an in-house built marker tool to evaluate the stability of the CBCT-based stereotactic space and its agreement with the standard frame-based stereotactic space. We imaged the tool with a CT indicator box using our CT-simulator at the beginning, middle, and end of the study period (6 weeks) for determining the frame-based stereotactic space. The tool was also scanned with the Icon's CBCT on a daily basis throughout the study period, and the CBCT images were used for determining the CBCT-based stereotactic space. The coordinates of each marker were determined in each CT and CBCT scan using the Leksell GammaPlan treatment planning software. The magnitudes of vector difference between the means of each marker in frame-based and CBCT-based stereotactic space ranged from 0.21 to 0.33 mm, indicating good agreement of CBCT-based and frame-based stereotactic space definition. Scanning 4-month later showed good prolonged stability of the CBCT-based stereotactic space definition. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Recurrent Juvenile Nasopharyngeal Angiofibroma Treated with Gamma Knife Surgery

Science.gov (United States)

Park, Chul-Kee; Paek, Sun Ha; Chung, Hyun-Tai; Jung, Hee-Won

2006-01-01

Radiosurgery has been rarely applied for juvenile nasopharyngeal angiofibroma (JNA) and cumulative reports are lacking. The authors report a case of successful treatment of recurred JNA with gamma knife surgery (GKS). A 48-yr-old man was presented with right visual acuity deterioration and brain magnetic resonance images (MRI) disclosed a 3 cm-sized intraorbital mass in the right orbit. He underwent a right fronto-temporal craniotomy and the mass was subtotally removed to preserve visual function. Histological diagnosis confirmed JNA in typical nature. However, the vision gradually worsened to fail four years after operation. MRI then showed regrowth of the tumor occupying most of the right orbit. GKS was done for the recurred lesion. A dose of 17 Gy was delivered to the 50% isodose line of tumor margin. During the following four-year follow-up period, the mass disappeared almost completely without any complications. Usually JNA can be exclusively diagnosed by radiological study alone. So this report of successful treatment of JNA with GKS may provide an important clue for the novel indication of GKS. PMID:16891831

Two Dimensional Verification of the Dose Distribution of Gamma Knife Model C using Monte Carlo Simulation with a Virtual Source

Energy Technology Data Exchange (ETDEWEB)

Kim, Tae-Hoon; Kim, Yong-Kyun; Lee, Cheol Ho; Son, Jaebum; Lee, Sangmin; Kim, Dong Geon; Choi, Joonbum; Jang, Jae Yeong [Hanyang University, Seoul (Korea, Republic of); Chung, Hyun-Tai [Seoul National University, Seoul (Korea, Republic of)

2016-10-15

Gamma Knife model C contains 201 {sup 60}Co sources located on a spherical surface, so that each beam is concentrated on the center of the sphere. In the last work, we simulated the Gamma Knife model C through Monte Carlo simulation code using Geant4. Instead of 201 multi-collimation system, we made one single collimation system that collects source parameter passing through the collimator helmet. Using the virtual source, we drastically reduced the simulation time to transport 201 gamma circle beams to the target. Gamma index has been widely used to compare two dose distributions in cancer radiotherapy. Gamma index pass rates were compared in two calculated results using the virtual source method and the original method and measured results obtained using radiocrhomic films. A virtual source method significantly reduces simulation time of a Gamma Knife Model C and provides equivalent absorbed dose distributions as that of the original method showing Gamma Index pass rate close to 100% under 1mm/3% criteria. On the other hand, it gives a little narrow dose distribution compared to the film measurement showing Gamma Index pass rate of 94%. More accurate and sophisticated examination on the accuracy of the simulation and film measurement is necessary.

Cerebral cavernous malformations. Serial magnetic resonance imaging findings in patients with and without gamma knife surgery

International Nuclear Information System (INIS)

Yoon Pyeong-Ho; Kim, Dong-Ik; Jeon Pyoung; Ryu, Young-Hoon; Hwang, Geum-Joo; Park, Sang-Joon

1998-01-01

To classify the cerebral cavernous malformations and to investigate the natural history of cavernous malformations according to the classification, 41 patients with 61 cavernous malformations (40 cavernous malformations from 22 patients treated with gamma knife surgery) were regularly followed up using MR imaging for a mean period of 25.5 months in treated cavernous malformations and 20.7 months in untreated cavernous malformations, respectively. Cavernous malformations were classified into four types. Follow-up MR images were analyzed to evaluate changes in size, signal intensity, rebleeding, and perilesional adverse reaction of irradiation. A total of 61 cavernous malformations including 17 in type I, 23 in type II, 10 in type III, and 11 in type IV showed usual degradation of blood product in 22 cavernous malformations, no change in shape and signal intensity in 31 cavernous malformations, and eight cavernous malformations with rebleedings in the serial MR images. In these eight cavernous malformations with rebleedings, six occurred in type II and two in type III, but none in type I or IV. Rebleedings were more frequent in type II than in other types. Adverse reaction of irradiation was observed in five of 22 patients treated with gamma knife surgery. Although most cerebral cavernous malformations showed evolution of hemorrhage or no change in size or shape on follow-up MR images, cerebral cavernous malformations represented as mixture of subacute and chronic hemorrhage with hemosiderin rim (type II) have a higher frequency to rebleed than other types of cerebral cavernous malformations. Cerebral cavernous malformations represented as hemosiderin deposition without central core (type IV) have a lower tendency to rebleed than other types and do not need any treatment. Most of the adverse reaction of irradiation after gamma knife surgery around cavernous malformations are transient findings and are considered to be perilesional edema. (K.H)

[Meta-analysis of needle-knife treatment on cervical spondylosis].

Science.gov (United States)

Kan, Li-Li; Wang, Hai-Dong; Liu, An-Guo

2013-11-01

To assess the efficacy of cervical spondylosis by needle-knife treatment according to the correlated literature of RCT,to compare advantages of needle-knife treatment. Randomized Controlled Trials about needle-knife treatment of cervical spondylosis were indexed from Chinese HowNet (CNKI) and Wanfang (WF) from 2000 to 2012, then were analyzed the efficacy by Review Manager 5.1 software. A total of 13 RCT literatures and 1 419 patients were included. The methods of included studies were poor in quality evaluation because of large sample and multi-center RCT studies was lacked, randomization method was not accurate enough, diagnostic criteria and efficacy evaluation were various, only four studies described long-term efficacy, most of the literature didn't describe the adverse event and fall off,all studies did not use the blind method. The Meta analysis outcome showed overall efficiency of needle-knife therapy was better than acupuncture and traction. Needle-knife therapy compared with Acupuncture, the total RR = 0.19, 95% confidence interval was (0.15, 0.24), P knife therapy is higher;compared with traction therapy, although,needle-knife therapy has a high overall effectiveness, but because of the loss of total sample size, the outcome RCT researches to confirm.

Repeat Gamma Knife surgery for vestibular schwannomas

Science.gov (United States)

Lonneville, Sarah; Delbrouck, Carine; Renier, Cécile; Devriendt, Daniel; Massager, Nicolas

2015-01-01

Background: Gamma Knife (GK) surgery is a recognized treatment option for the management of small to medium-sized vestibular schwannoma (VS) associated with high-tumor control and low morbidity. When a radiosurgical treatment fails to stop tumor growth, repeat GK surgery can be proposed in selected cases. Methods: A series of 27 GK retreatments was performed in 25 patients with VS; 2 patients underwent three procedures. The median time interval between GK treatments was 45 months. The median margin dose used for the first, second, and third GK treatments was 12 Gy, 12 Gy, and 14 Gy, respectively. Six patients (4 patients for the second irradiation and 2 patients for the third irradiation) with partial tumor regrowth were treated only on the growing part of the tumor using a median margin dose of 13 Gy. The median tumor volume was 0.9, 2.3, and 0.7 cc for the first, second, and third treatments, respectively. Stereotactic positron emission tomography (PET) guidance was used for dose planning in 6 cases. Results: Mean follow-up duration was 46 months (range 24–110). At the last follow-up, 85% of schwannomas were controlled. The tumor volume decreased, remained unchanged, or increased after retreatment in 15, 8, and 4 cases, respectively. Four patients had PET during follow-up, and all showed a significant metabolic decrease of the tumor. Hearing was not preserved after retreatment in any patients. New facial or trigeminal palsy did not occur after retreatment. Conclusions: Our results support the long-term efficacy and low morbidity of repeat GK treatment for selected patients with tumor growth after initial treatment. PMID:26500799

A simplified model of the source channel of the Leksell GammaKnife tested with PENELOPE.

Science.gov (United States)

Al-Dweri, Feras M O; Lallena, Antonio M; Vilches, Manuel

2004-06-21

Monte Carlo simulations using the code PENELOPE have been performed to test a simplified model of the source channel geometry of the Leksell GammaKnife. The characteristics of the radiation passing through the treatment helmets are analysed in detail. We have found that only primary particles emitted from the source with polar angles smaller than 3 degrees with respect to the beam axis are relevant for the dosimetry of the Gamma Knife. The photon trajectories reaching the output helmet collimators at (x, v, z = 236 mm) show strong correlations between rho = (x2 + y2)(1/2) and their polar angle theta, on one side, and between tan(-1)(y/x) and their azimuthal angle phi, on the other. This enables us to propose a simplified model which treats the full source channel as a mathematical collimator. This simplified model produces doses in good agreement with those found for the full geometry. In the region of maximal dose, the relative differences between both calculations are within 3%, for the 18 and 14 mm helmets, and 10%, for the 8 and 4 mm ones. Besides, the simplified model permits a strong reduction (larger than a factor 15) in the computational time.

WE-G-BRA-08: Failure Modes and Effects Analysis (FMEA) for Gamma Knife Radiosurgery

International Nuclear Information System (INIS)

Xu, Y; Bhatnagar, J; Bednarz, G; Flickinger, J; Arai, Y; Huq, M Saiful; Vacsulka, J; Monaco, E; Niranjan, A; Lunsford, L Dade; Feng, W

2015-01-01

Purpose: To perform a failure modes and effects analysis (FMEA) study for Gamma Knife (GK) radiosurgery processes at our institution based on our experience with the treatment of more than 13,000 patients. Methods: A team consisting of medical physicists, nurses, radiation oncologists, neurosurgeons at the University of Pittsburgh Medical Center and an external physicist expert was formed for the FMEA study. A process tree and a failure mode table were created for the GK procedures using the Leksell GK Perfexion and 4C units. Three scores for the probability of occurrence (O), the severity (S), and the probability of no detection (D) for failure modes were assigned to each failure mode by each professional on a scale from 1 to 10. The risk priority number (RPN) for each failure mode was then calculated (RPN = OxSxD) as the average scores from all data sets collected. Results: The established process tree for GK radiosurgery consists of 10 sub-processes and 53 steps, including a sub-process for frame placement and 11 steps that are directly related to the frame-based nature of the GK radiosurgery. Out of the 86 failure modes identified, 40 failure modes are GK specific, caused by the potential for inappropriate use of the radiosurgery head frame, the imaging fiducial boxes, the GK helmets and plugs, and the GammaPlan treatment planning system. The other 46 failure modes are associated with the registration, imaging, image transfer, contouring processes that are common for all radiation therapy techniques. The failure modes with the highest hazard scores are related to imperfect frame adaptor attachment, bad fiducial box assembly, overlooked target areas, inaccurate previous treatment information and excessive patient movement during MRI scan. Conclusion: The implementation of the FMEA approach for Gamma Knife radiosurgery enabled deeper understanding of the overall process among all professionals involved in the care of the patient and helped identify potential

Gamma knife radio-surgery in meningiomas: decisive variables in the dose prescription during 14 years; Radiocirugia gamma knife en meningiomas: variables determinantes en la prescripcion de dosis durante 14 anos

Energy Technology Data Exchange (ETDEWEB)

Dominguez O, X.; Diaz A, P.; Toledo B, V.; Zazueta L, F., E-mail: pdiaz@hospitalsanjavier.co [Hospital San Javier, Pablo Casals No. 640, Col. Prados Providencia, 44670 Guadalajara, Jalisco (Mexico)

2010-09-15

A comparative study is presented among the variables of dose prescription in twelve cases of treated meningiomas from 1997 to 2009 in the Gamma Knife Unit of the Hospital San Javier. An evolution is observed in the definition of the treatment volumes, collimators election and matrix of dose calculation, this evolution has been due so much to the technological advance associated to the image acquisition systems: Computerized axial tomography, Images by magnetic resonance and Angiography by digital subtraction, as well as to the indexes adoption that are used to qualify among different treatment plans. The differences among the analyzed periods demonstrate a favorable learning curve that have influenced contributing to a treatment with a minor irradiated volume due to the application of theoretical models used in this installation, attenuating the risk of peripheral unexpected complications to the treated volume. (Author)

Gamma Knife radiosurgery for cerebral arteriovenous malformations in children/adolescents and adults. Part II: Differences in obliteration rates, treatment-obliteration intervals, and prognostic factors

International Nuclear Information System (INIS)

Nicolato, Antonio; Lupidi, Francesco; Sandri, Marco F. Dr. Econom.; Foroni, Roberto; Zampieri, Piergiuseppe; Mazza, Carlo; Pasqualin, Alberto; Beltramello, Alberto; Gerosa, Massimo

2006-01-01

Purpose: To evaluate and compare obliteration rates (OBRs) and treatment-obliteration intervals (TOIs) for cerebral arteriovenous malformations (cAVMs) treated with Gamma Knife radiosurgery in children/adolescents and adults; and to determine factors predicting the OBR and TOI in these two populations. Methods and Materials: This study concerned 62 children/adolescents and 193 adults observed for ≥3 years. Fisher exact two-tailed and Wilcoxon rank-sum tests, multiple logistics, and Cox proportional hazard models were used for statistical analysis. Results: The overall OBR was 85.5% in children/adolescents and 87.6% in adults (p 0.671), but children/adolescents showed higher 36-month actuarial OBRs (69.35%) and shorter median TOIs (25.7 months) than adults (66.84% and 28.2 months; p 0.006 and p = 0.017, respectively). In children/adolescents, lower Spetzler-Martin grades (p = 0.043) and younger age (p = 0.019) correlated significantly with OBRs, and lower Spetzler-Martin grades (p 0.024) and noneloquent cAVM locations (p = 0.046) with TOIs. In adults, low flow through the cAVM and 3 volume were associated with both OBR and TOI (p 0.012 and p = 0.002, respectively). Conclusions: The differences in OBRs within 3 years and TOIs, although slight, seem to show that pediatric cAVMs behave differently from those in adults after Gamma Knife radiosurgery

CyberKnife radiosurgery: Precision without incision

Directory of Open Access Journals (Sweden)

Enja Siva Prasad Reddy

2015-01-01

Full Text Available CyberKnife stereotactic radiosurgery system is an innovative, effective, frameless, non-invasive substitute for conventional surgical treatment of cancer. It works on the principle of stereotaxy. It is used for the treatment of both cancerous and non-cancerous tumors, intracranial lesions, tumors of lung, spine, prostate, and kidney, recurrent cases of oral squamous cell carcinoma, arteriovenous malformation, and trigeminal neuralgia. It has an advantage over other systems like Gamma knife radiosurgery and linear accelerator (LINAC-based systems, as it is frameless, has submillimeter accuracy, does not affect the normal cells adjacent to the lesion, and tracks the lesion in synchronization with the patient′s respiratory rate. The future of CyberKnife encompasses possibilities such as incremental improvements in accuracy and better shaping of the field of radiation and would certainly allow extension of radiosurgery as an effective substitute for chemotherapy. This paper aims to review and highlight the immense potential that CyberKnife holds in the field of dentistry in treating disorders of the head and neck region, thereby ensuring enhanced longevity for the patients.

Radiosurgery of epidermoid tumors with gamma knife. Possiblity of radiosurgical nerve decompression

International Nuclear Information System (INIS)

Kida, Yoshihisa; Yoshimoto, Masayuki; Hasegawa, Toshinori; Fujitani, Shigeru

2006-01-01

Long-term results of radiosurgery for epidermoid tumors are reported. There are 7 cases including 2 males and 5 females, ages ranging from 6 to 46 (mean: 33.3 years). At radiosurgery whole tumor was covered in 4 cases and partially covered in 3 cases in attempting to relieve cranial nerve signs like trigeminal neuralgia and facial spasm. The mean maximum and marginal doses were 25.6 Gy and 14.6 Gy respectively. In the mean follow-up of 52.7 months, all the tumors showed good tumor control without any progression and tumor shrinkage has been confirmed in 2 out of the 7 cases. Symptomatic trigeminal neuralgia improved or disappeared in all 4 cases and facial spasm disappeared in one. No neurological deterioration was found in any of the cases after the treatment. In conclusion, it is apparent that epidermoid tumors do respond well to radiosurgery and the accompanying hyperactive dysfunction of cranial nerves is significantly improved by gamma knife treatment with either entire or partial tumor coverage. Therefore the radiosurgical nerve decompression for epidermoid tumor seems to be achieved by gamma-radiosurgery. (author)

Gamma knife radiosurgery for benign cavernous sinus tumors. Treatment concept and outcomes in 120 cases

International Nuclear Information System (INIS)

Hayashi, Motohiro; Chernov, Mikhail; Tamura, Noriko

2012-01-01

Availability of modern computer-aided robotized devices, such as the Automatic Positioning System (APS TM ; Elekta Instruments AB, Stockholm, Sweden) and Perfexion TM (Elekta Instruments AB), allowed us to develop the original concept of robotic gamma knife microradiosurgery, which is based on the very precise irradiation of the lesion with regard to conformity and selectivity; intentional avoidance of the excessive irradiation of functionally-important anatomical structures, particularly cranial nerves, located both within and in the vicinity of the target; and delivery of sufficient irradiation energy to the tumor with the intention to attain lesion shrinkage, while keeping the marginal dose sufficiently low for prevention of possible complications. The results of such treatment strategy were evaluated retrospectively in 120 patients with benign cavernous sinus neoplasms (pituitary adenomas, meningiomas, schwannomas, and hemangiomas), who were followed up from 24 to 78 months (mean 47 months) after radiosurgery. Tumor growth control and shrinkage rates were 98% and 68%, respectively. More than 50% volume reduction was noted in 25% of lesions. The most prominent volumetric tumor response was observed in hemangiomas, followed by schwannomas, pituitary adenomas, and meningiomas. Treatment-related complications were marked in 7% of cases, and were mainly related to transient isolated cranial neuropathy appearing within several months after radiosurgery. Major morbidity was limited to one patient (0.8%). Application of microradiosurgical treatment principles provides effective and safe management of benign cavernous sinus tumors and is associated with high probability of lesion shrinkage and minimal risk of complications. (author)

Dosimetry of Gamma Knife and linac-based radiosurgery using radiochromic and diode detectors

International Nuclear Information System (INIS)

Somigliana, A.; Borelli, S.; Zonca, G.; Pignoli, E.; Loi, G.; Marchesini, R.; Cattaneo, G.M.; Fiorino, C.; Vecchio, A. del; Calandrino, R.

1999-01-01

In stereotactic radiosurgery the choice of appropriate detectors, whether for absolute or relative dosimetry, is very important due to the steep dose gradient and the incomplete lateral electronic equilibrium. For both linac-based and Leksell Gamma Knife radiosurgery units, we tested the use of calibrated radiochromic film to measure absolute doses and relative dose distributions. In addition a small diode was used to estimate the relative output factors. The data obtained using radiochromic and diode detectors were compared with measurements performed with other conventional methods of dosimetry, with calculated values by treatment planning systems and with data prestored in the treatment planning system supplied by the Leksell Gamma Knife (LGK) vendor. Two stereotactic radiosurgery techniques were considered: Leksell Gamma Knife (using γ-rays from 60 Co) and linac-based radiosurgery (LR) (6 MV x-rays). Different detectors were used for both relative and absolute dosimetry: relative output factors (OFs) were estimated by using radiochromic and radiographic films and a small diode; relative dose distributions in the axial and coronal planes of a spherical polystyrene phantom were measured using radiochromic film and calculated by two different treatment planning systems (TPSs). The absolute dose at the sphere centre was measured by radiochromic film and a small ionization chamber. An accurate selection of radiochromic film was made: samples of unexposed film showing a percentage standard deviation of less than 3% were used for relative dose profiles, and for absolute dose and OF evaluations this value was reduced to 1.5%. Moreover a proper calibration curve was made for each set of measurements. With regard to absolute doses, the results obtained with the ionization chamber are in good correlation with radiochromic film-generated data, for both LGK and LR, showing a dose difference of less than 1%. The output factor evaluations, performed using different methods

Repeat Gamma Knife Radiosurgery for Trigeminal Neuralgia

International Nuclear Information System (INIS)

Aubuchon, Adam C.; Chan, Michael D.; Lovato, James F.; Balamucki, Christopher J.; Ellis, Thomas L.; Tatter, Stephen B.; McMullen, Kevin P.; Munley, Michael T.; Deguzman, Allan F.; Ekstrand, Kenneth E.; Bourland, J. Daniel; Shaw, Edward G.

2011-01-01

Purpose: Repeat gamma knife stereotactic radiosurgery (GKRS) for recurrent or persistent trigeminal neuralgia induces an additional response but at the expense of an increased incidence of facial numbness. The present series summarized the results of a repeat treatment series at Wake Forest University Baptist Medical Center, including a multivariate analysis of the data to identify the prognostic factors for treatment success and toxicity. Methods and Materials: Between January 1999 and December 2007, 37 patients underwent a second GKRS application because of treatment failure after a first GKRS treatment. The mean initial dose in the series was 87.3 Gy (range, 80–90). The mean retreatment dose was 84.4 Gy (range, 60–90). The dosimetric variables recorded included the dorsal root entry zone dose, pons surface dose, and dose to the distal nerve. Results: Of the 37 patients, 81% achieved a >50% pain relief response to repeat GKRS, and 57% experienced some form of trigeminal dysfunction after repeat GKRS. Two patients (5%) experienced clinically significant toxicity: one with bothersome numbness and one with corneal dryness requiring tarsorraphy. A dorsal root entry zone dose at repeat treatment of >26.6 Gy predicted for treatment success (61% vs. 32%, p = .0716). A cumulative dorsal root entry zone dose of >84.3 Gy (72% vs. 44%, p = .091) and a cumulative pons surface dose of >108.5 Gy (78% vs. 44%, p = .018) predicted for post-GKRS numbness. The presence of any post-GKRS numbness predicted for a >50% decrease in pain intensity (100% vs. 60%, p = .0015). Conclusion: Repeat GKRS is a viable treatment option for recurrent trigeminal neuralgia, although the patient assumes a greater risk of nerve dysfunction to achieve maximal pain relief.

Repeat Gamma Knife Radiosurgery for Trigeminal Neuralgia

Energy Technology Data Exchange (ETDEWEB)

Aubuchon, Adam C., E-mail: acaubuchon@gmail.com [Department of Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Chan, Michael D. [Department of Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Lovato, James F. [Department of Public Health Sciences, Wake Forest University School of Medicine, Winston-Salem, NC (United States); Balamucki, Christopher J. [Department of Radiation Oncology, University of Florida, Gainesville, FL (United States); Ellis, Thomas L.; Tatter, Stephen B. [Department of Neurosurgery, Wake Forest University School of Medicine, Winston-Salem, NC (United States); McMullen, Kevin P.; Munley, Michael T.; Deguzman, Allan F.; Ekstrand, Kenneth E.; Bourland, J. Daniel; Shaw, Edward G. [Department of Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC (United States)

2011-11-15

Purpose: Repeat gamma knife stereotactic radiosurgery (GKRS) for recurrent or persistent trigeminal neuralgia induces an additional response but at the expense of an increased incidence of facial numbness. The present series summarized the results of a repeat treatment series at Wake Forest University Baptist Medical Center, including a multivariate analysis of the data to identify the prognostic factors for treatment success and toxicity. Methods and Materials: Between January 1999 and December 2007, 37 patients underwent a second GKRS application because of treatment failure after a first GKRS treatment. The mean initial dose in the series was 87.3 Gy (range, 80-90). The mean retreatment dose was 84.4 Gy (range, 60-90). The dosimetric variables recorded included the dorsal root entry zone dose, pons surface dose, and dose to the distal nerve. Results: Of the 37 patients, 81% achieved a >50% pain relief response to repeat GKRS, and 57% experienced some form of trigeminal dysfunction after repeat GKRS. Two patients (5%) experienced clinically significant toxicity: one with bothersome numbness and one with corneal dryness requiring tarsorraphy. A dorsal root entry zone dose at repeat treatment of >26.6 Gy predicted for treatment success (61% vs. 32%, p = .0716). A cumulative dorsal root entry zone dose of >84.3 Gy (72% vs. 44%, p = .091) and a cumulative pons surface dose of >108.5 Gy (78% vs. 44%, p = .018) predicted for post-GKRS numbness. The presence of any post-GKRS numbness predicted for a >50% decrease in pain intensity (100% vs. 60%, p = .0015). Conclusion: Repeat GKRS is a viable treatment option for recurrent trigeminal neuralgia, although the patient assumes a greater risk of nerve dysfunction to achieve maximal pain relief.

Combined embolization and gamma knife radiosurgery for cerebral arteriovenous malformations

International Nuclear Information System (INIS)

Guo, W.Y.; Wikholm, G.; Karlsson, B.; Lindquist, C.; Svendsen, P.; Ericson, K.

1993-01-01

In a study of 46 patients with cerebral arteriovenous malformations (AVMs) the value of combining embolization and gamma knife radiosurgery was assessed. In 35 patients with large grade III to V AVMs (Spetzler-Martin system) staged combined treatment was planned. In 11 patients, radiosurgery complemented embolization for a residual AVM. The number of embolization sessions ranged from 1 to 7 (median 2). Twenty-six patients needed multiple embolization sessions. In 28 patients the grade of AVMs decreased as a result of embolization. In 16 patients collateral feeding vessels developed after embolization which made delineation of the residual nidus difficult. The time lag between the last embolization and radiosurgery ranged from 1 to 24 months (median 4). Nineteen of 35 large grade III to V AVMs were possible to treat by radiosurgery following embolization. In the 46 patients complications occurred in 9 from embolization and in 2 from radiosurgery. Two patients had transient and 9 had permanent neurologic deficits. It is concluded that embolization facilitates radiosurgery for some large AVMs and therefore this combined treatment has a role in the management of AVMs. (orig.)

A simplified model of the source channel of the Leksell GammaKnife (registered) tested with PENELOPE

International Nuclear Information System (INIS)

Al-Dweri, Feras M O; Lallena, Antonio M; Vilches, Manuel

2004-01-01

Monte Carlo simulations using the code PENELOPE have been performed to test a simplified model of the source channel geometry of the Leksell GammaKnife (registered) . The characteristics of the radiation passing through the treatment helmets are analysed in detail. We have found that only primary particles emitted from the source with polar angles smaller than 3 deg. with respect to the beam axis are relevant for the dosimetry of the Gamma Knife. The photon trajectories reaching the output helmet collimators at (x, y, z = 236 mm) show strong correlations between ρ = (x 2 + y 2 ) 1/2 and their polar angle θ, on one side, and between tan -1 (y/x) and their azimuthal angle φ, on the other. This enables us to propose a simplified model which treats the full source channel as a mathematical collimator. This simplified model produces doses in good agreement with those found for the full geometry. In the region of maximal dose, the relative differences between both calculations are within 3%, for the 18 and 14 mm helmets, and 10%, for the 8 and 4 mm ones. Besides, the simplified model permits a strong reduction (larger than a factor 15) in the computational time

A simplified model of the source channel of the Leksell GammaKnife (registered) tested with PENELOPE

Energy Technology Data Exchange (ETDEWEB)

Al-Dweri, Feras M O [Departamento de FIsica Moderna, Universidad de Granada, E-18071 Granada (Spain); Lallena, Antonio M [Departamento de FIsica Moderna, Universidad de Granada, E-18071 Granada (Spain); Vilches, Manuel [Servicio de RadiofIsica, Hospital ClInico ' San Cecilio' , Avda. Dr Oloriz, 16, E-18012 Granada (Spain)

2004-06-21

Monte Carlo simulations using the code PENELOPE have been performed to test a simplified model of the source channel geometry of the Leksell GammaKnife (registered) . The characteristics of the radiation passing through the treatment helmets are analysed in detail. We have found that only primary particles emitted from the source with polar angles smaller than 3 deg. with respect to the beam axis are relevant for the dosimetry of the Gamma Knife. The photon trajectories reaching the output helmet collimators at (x, y, z = 236 mm) show strong correlations between {rho} = (x{sup 2} + y{sup 2}){sup 1/2} and their polar angle {theta}, on one side, and between tan{sup -1}(y/x) and their azimuthal angle {phi}, on the other. This enables us to propose a simplified model which treats the full source channel as a mathematical collimator. This simplified model produces doses in good agreement with those found for the full geometry. In the region of maximal dose, the relative differences between both calculations are within 3%, for the 18 and 14 mm helmets, and 10%, for the 8 and 4 mm ones. Besides, the simplified model permits a strong reduction (larger than a factor 15) in the computational time.

A simplified model of the source channel of the Leksell GammaKnife® tested with PENELOPE

Science.gov (United States)

Al-Dweri, Feras M. O.; Lallena, Antonio M.; Vilches, Manuel

2004-06-01

Monte Carlo simulations using the code PENELOPE have been performed to test a simplified model of the source channel geometry of the Leksell GammaKnife®. The characteristics of the radiation passing through the treatment helmets are analysed in detail. We have found that only primary particles emitted from the source with polar angles smaller than 3° with respect to the beam axis are relevant for the dosimetry of the Gamma Knife. The photon trajectories reaching the output helmet collimators at (x, y, z = 236 mm) show strong correlations between rgr = (x2 + y2)1/2 and their polar angle thgr, on one side, and between tan-1(y/x) and their azimuthal angle phgr, on the other. This enables us to propose a simplified model which treats the full source channel as a mathematical collimator. This simplified model produces doses in good agreement with those found for the full geometry. In the region of maximal dose, the relative differences between both calculations are within 3%, for the 18 and 14 mm helmets, and 10%, for the 8 and 4 mm ones. Besides, the simplified model permits a strong reduction (larger than a factor 15) in the computational time.

Verification of source and collimator configuration for Gamma Knife Perfexion using panoramic imaging

International Nuclear Information System (INIS)

Cho, Young-Bin; Prooijen, Monique van; Jaffray, David A.; Islam, Mohammad K.

2010-01-01

Purpose: The new model of stereotactic radiosurgery system, Gamma Knife Perfexion, allows automatic selection of built-in collimation, eliminating the need for the time consuming manual collimator installation required with previous models. However, the configuration of sources and collimators inside the system does not permit easy access for the verification of the selected collimation. While the conventional method of exposing a film at the isocenter is useful for obtaining composite dose information, it is difficult to interpret the data in terms of the integrity of each individual source and corresponding collimation. The primary aim of this study was to develop a method of verifying the geometric configuration of the sources and collimator modules of the Gamma Knife Perfexion. In addition, the method was extended to make dose measurements and verify the accuracy of dose distributions calculated by the mathematical formalism used in the treatment planning system, Leksell Gamma Plan. Methods: A panoramic view of all of 192 cobalt sources was simultaneously acquired by exposing a radiochromic film wrapped around the surface of a cylindrical phantom. The center of the phantom was mounted at the isocenter with its axis aligned along the longitudinal axis of the couch. The sizes and shapes of the source images projected on the phantom surface were compared to those calculated based on the manufacturer's design specifications. The measured dose at various points on the film was also compared to calculations using the algorithm of the planning system. Results: The panoramic images allowed clear identification of each of the 192 sources, verifying source integrity and selected collimator sizes. Dose on the film surface is due to the primary beam as well as phantom scatter and leakage contributions. Therefore, the dose at a point away from the isocenter cannot be determined simply based on the proportionality of collimator output factors; the use of a dose computation

Risk and dose assessment methods in gamma knife QA

International Nuclear Information System (INIS)

Banks, W.W.; Jones, E.D.; Rathbun, P.

1992-10-01

Traditional methods used in assessing risk in nuclear power plants may be inappropriate to use in assessing medical radiation risks. The typical philosophy used in assessing nuclear reactor risks is machine dominated with only secondary attention paid to the human component, and only after critical machine failure events have been identified. In assessing the risk of a misadministrative radiation dose to patients, the primary source of failures seems to stem overwhelmingly, from the actions of people and only secondarily from machine mode failures. In essence, certain medical misadministrations are dominated by human events not machine failures. Radiological medical devices such as the Leksell Gamma Knife are very simple in design, have few moving parts, and are relatively free from the risks of wear when compared with a nuclear power plant. Since there are major technical differences between a gamma knife and a nuclear power plant, one must select a particular risk assessment method which is sensitive to these system differences and tailored to the unique medical aspects of the phenomena under study. These differences also generate major shifts in the philosophy and assumptions which drive the risk assessment (Machine-centered vs Person-centered) method. We were prompted by these basic differences to develop a person-centered approach to risk assessment which would reflect these basic philosophical and technological differences, have the necessary resolution in its metrics, and be highly reliable (repeatable). The risk approach chosen by the Livermore investigative team has been called the ''Relative Risk Profile Method'' and has been described in detail by Banks and Paramore, (1983)

Lesion evolution after gamma knife irradiation observed by magnetic resonance imaging

Czech Academy of Sciences Publication Activity Database

Jirák, D.; Náměstková, K.; Herynek, V.; Liščák, R.; Vymazal, J.; Mareš, Vladislav; Syková, Eva; Hájek, M.

2007-01-01

Roč. 83, č. 4 (2007), s. 237-244 ISSN 0955-3002 R&D Projects: GA MŠk 1M0538; GA MŠk(CZ) LC554 Grant - others:EU(DE) 512146 Institutional research plan: CEZ:AV0Z50390512; CEZ:AV0Z50110509 Source of funding: R - rámcový projekt EK Keywords : Gamma knife * Rat brain * Magnetic resonance imaging Subject RIV: FH - Neurology Impact factor: 1.468, year: 2007

Quantifying and improving the efficiency of Gamma Knife treatment plans for brain metastases: results of a 1-year audit.

Science.gov (United States)

Wright, Gavin; Hatfield, Paul; Loughrey, Carmel; Reiner, Beatrice; Bownes, Peter

2014-12-01

A method for quantifying the efficiency of Gamma Knife treatment plans for metastases was previously implemented by the authors to retrospectively identify the least efficient plans and has provided insights into improved planning strategies. The aim of the current work was to ascertain whether those insights led to improved treatment plans. Following completion of the initial study, a 1-year audit of metastasis plans created at St. James's Institute of Oncology was carried out. Audited recent plans were compared with the earlier plans of the initial study, in terms of their efficiency and dosimetric quality. The statistical significance of any differences between relevant plan parameters was quantified by Mann-Whitney U-tests. Comparisons were made between all plans and repeated for a reduced set of plans from which the smallest lesions treated with a single 4-mm shot were excluded. The plan parameters compared were a plan efficiency index (PEI), the number of shots, Paddick conformity index (PCI), gradient index (GI), and percent coverage (of the lesion by the prescription isodose). A total of 157 metastatic lesions were included in the audit and were compared with 241 in the initial study. In a comparison of all cases, the audited plans achieved a higher median PEI score than did the earlier plans from the initial study (1.08 vs 1.02), indicating improved efficiency of the audited plans. When the smallest lesions (for which there was little scope for varying plan strategy) were discounted, the improvement in median PEI score was greater (1.23 vs 1.03, p planning strategy yielding these efficiency improvements did not rely on the use of significantly fewer shots (median 11 vs 11 shots, p = 0.924), nor did it result in significant detriment to dosimetric quality (median coverage 99% vs 99%, median PCI 0.84 vs 0.83, p = 0.449, and median GI 2.72 vs 2.67, p = 0.701, audited plans vs initial plans, respectively). Choice of planning strategy can substantially affect

MR imaging response of cerebral metastases and peritumoral edema after Gamma Knife surgery

International Nuclear Information System (INIS)

Guo Qi; Wang Congyin; Zhang Xuening; Zheng Jingjing; Xu Desheng; Zhang Yipei

2012-01-01

Objective: To evaluation the treatment response of Gamma Knife surgery (GKS) for the control of cerebral metastases and peritumoral edema using standard MRI. Method: 42 consecutive patients with 75 metastatic lesions were recruited in this study (28 men, 14 women; mean age 60±12 years). Gadolinium enhancement T 1 WI scans were performed on one day before and three months after GKS. Treatment response was evaluated by calculating the changes of tumor volume and edema index before and after GKS. Results: Mean tumor volumes on the baseline and post treatment were 7.0 cm 3 and 3.3 cm 3 respectively. Mean peritumoral edema indexes were 9.9 and 4.3 respectively. Tumor growth control rate and peritumoral edema control rate were 91% and 85% respectively. Conclusion: GKS is effective for both brain metastasis and peritumoral edema, and the tumor volume influences GKS efficacy. Conventional MRI provides useful information to predict treatment response of GKS for cerebral metastasis. (authors)

Gamma knife radiosurgery for typical trigeminal neuralgia: An institutional review of 108 patients

Science.gov (United States)

Elaimy, Ameer L.; Lamm, Andrew F.; Demakas, John J.; Mackay, Alexander R.; Lamoreaux, Wayne T.; Fairbanks, Robert K.; Pfeffer, Robert D.; Cooke, Barton S.; Peressini, Benjamin J.; Lee, Christopher M.

2013-01-01

Background: In this study, we present the previously unreported pain relief outcomes of 108 patients treated at Gamma Knife of Spokane for typical trigeminal neuralgia (TN) between 2002 and 2011. Methods: Pain relief outcomes were measured using the Barrow Neurological Institute (BNI) pain intensity scale. In addition, the effects gender, age at treatment, pain laterality, previous surgical treatment, repeat Gamma Knife radiosurgery (GKRS), and maximum radiosurgery dose have on patient pain relief outcomes were retrospectively analyzed. Statistical analysis was performed using Andersen 95% confidence intervals, approximate confidence intervals for log hazard ratios, and multivariate Cox proportional hazard models. Results: All 108 patients included in this study were grouped into BNI class IV or V prior to GKRS. The median clinical follow-up time was determined to be 15 months. Following the first GKRS procedure, 71% of patients were grouped into BNI class I-IIIb (I = 31%; II = 3%; IIIa = 19%; IIIb = 18%) and the median duration of pain relief for those patients was determined to be 11.8 months. New facial numbness was reported in 19% of patients and new facial paresthesias were reported in 7% of patients after the first GKRS procedure. A total of 19 repeat procedures were performed on the 108 patients included in this study. Following the second GKRS procedure, 73% of patients were grouped into BNI class I-IIIb (I = 44%; II = 6%; IIIa = 17%, IIIb = 6%) and the median duration of pain relief for those patients was determined to be 4.9 months. For repeat procedures, new facial numbness was reported in 22% of patients and new facial paresthesias were reported in 6% of patients. Conclusions: GKRS is a safe and effective management approach for patients diagnosed with typical TN. However, further studies and supporting research is needed on the effects previous surgical treatment, number of radiosurgery procedures, and maximum radiosurgery dose have on GKRS clinical

Determination of small field synthetic single-crystal diamond detector correction factors for CyberKnife, Leksell Gamma Knife Perfexion and linear accelerator.

Science.gov (United States)

Veselsky, T; Novotny, J; Pastykova, V; Koniarova, I

2017-12-01

The aim of this study was to determine small field correction factors for a synthetic single-crystal diamond detector (PTW microDiamond) for routine use in clinical dosimetric measurements. Correction factors following small field Alfonso formalism were calculated by comparison of PTW microDiamond measured ratio M Qclin fclin /M Qmsr fmsr with Monte Carlo (MC) based field output factors Ω Qclin,Qmsr fclin,fmsr determined using Dosimetry Diode E or with MC simulation itself. Diode measurements were used for the CyberKnife and Varian Clinac 2100C/D linear accelerator. PTW microDiamond correction factors for Leksell Gamma Knife (LGK) were derived using MC simulated reference values from the manufacturer. PTW microDiamond correction factors for CyberKnife field sizes 25-5 mm were mostly smaller than 1% (except for 2.9% for 5 mm Iris field and 1.4% for 7.5 mm fixed cone field). The correction of 0.1% and 2.0% for 8 mm and 4 mm collimators, respectively, needed to be applied to PTW microDiamond measurements for LGK Perfexion. Finally, PTW microDiamond M Qclin fclin /M Qmsr fmsr for the linear accelerator varied from MC corrected Dosimetry Diode data by less than 0.5% (except for 1 × 1 cm 2 field size with 1.3% deviation). Regarding low resulting correction factor values, the PTW microDiamond detector may be considered an almost ideal tool for relative small field dosimetry in a large variety of stereotactic and radiosurgery treatment devices. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Gamma knife surgery for pineal region tumors: an alternative strategy for negative pathology

Energy Technology Data Exchange (ETDEWEB)

Wang, Peng [Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu (China); Department of Neurosurgery, The Fifth People' s Hospital of Chengdu, Chengdu (China); Mao, Qing; Wang, Wei; Zhou, Liang-Xue; Liu, Yan-Hui, E-mail: liuyanhui9@gmail.com [Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu (China)

2014-03-01

Objective: pineal region tumors (PRTs) are uncommon, and treatments vary among neoplasm types. The authors report their experience with gamma knife surgery (GKS) as an initial treatment in a series of PRT patients with unclear pathological diagnoses. Method: seventeen PRT patients with negative pathology who underwent GKS were retrospectively studied. Nine patients had further whole-brain and spinal cord radiotherapy and chemotherapy 6-9 months after GKS. Results: Sixteen of 17 cases were followed up over a mean of 33.3 months. The total response rate was 75%, and the control rate was 81.3%. No obvious neurological deficits or complications were attributable to GKS. Conclusion: the findings indicate that GKS may be an alternative strategy in selected PRT patients who have negative pathological diagnoses, and that good outcomes and quality of life can be obtained with few complications. (author)

A randomised trial to compare cognitive outcome after gamma knife radiosurgery versus whole brain radiation therapy in patients with multiple brain metastases : Research protocol CAR-study B

NARCIS (Netherlands)

Schimmel, W.C.M.; Verhaak, E.; Hanssens, Patrick E. J.; Gehring, K.; Sitskoorn, M.M.

2018-01-01

Background Gamma Knife radiosurgery (GKRS) is increasingly applied in patients with multiple brain metastases and is expected to have less adverse effects in cognitive functioning than whole brain radiation therapy (WBRT). Effective treatment with the least negative cognitive side effects is

Assessment of absorbed dose to thyroid, parotid and ovaries in patients undergoing Gamma Knife radiosurgery

International Nuclear Information System (INIS)

Hasanzadeh, H; Sharafi, A; Verdi, M Allah; Nikoofar, A

2006-01-01

Stereotactic radiosurgery was originally introduced by Lars Leksell in 1951. This treatment refers to the noninvasive destruction of an intracranial target localized stereotactically. The purpose of this study was to identify the dose delivered to the parotid, ovaries, testis and thyroid glands during the Gamma Knife radiosurgery procedure. A three-dimensional, anthropomorphic phantom was developed using natural human bone, paraffin and sodium chloride as the equivalent tissue. The phantom consisted of a thorax, head and neck and hip. In the natural places of the thyroid, parotid (bilateral sides) and ovaries (midline), some cavities were made to place TLDs. Three TLDs were inserted in a batch with 1 cm space between the TLDs and each batch was inserted into a single cavity. The final depth of TLDs was 3 cm from the surface for parotid and thyroid and was 15 cm for the ovaries. Similar batches were placed superficially on the phantom. The phantom was gamma irradiated using a Leksell model C Gamma Knife unit. Subsequently, the same batches were placed superficially over the thyroid, parotid, testis and ovaries in 30 patients (15 men and 15 women) who were undergoing radiosurgery treatment for brain tumours. The mean dosage for treating these patients was 14.48 ± 3.06 Gy (10.5-24 Gy) to a mean tumour volume of 12.30 ± 9.66 cc (0.27-42.4 cc) in the 50% isodose curve. There was no significant difference between the superficial and deep batches in the phantom studies (P-value < 0.05). The mean delivered doses to the parotid, thyroid, ovaries and testis in human subjects were 21.6 ± 15.1 cGy, 9.15 ± 3.89 cGy, 0.47 ± 0.3 cGy and 0.53 ± 0.31 cGy, respectively. The data can be used in making decisions for special clinical situations such as treating pregnant patients or young patients with benign lesions who need radiosurgery for eradication of brain tumours

Is it possible to avoid hypopituitarism after irradiation of pituitary adenomas by the Leksell gamma knife

Czech Academy of Sciences Publication Activity Database

Marek, J.; Ježková, J.; Hána, V.; Kršek, M.; Bandúrová, Ľ.; Pecen, Ladislav; Vladyka, V.; Liščák, R.

2011-01-01

Roč. 164, č. 2 (2011), s. 169-178 ISSN 0804-4643 Institutional research plan: CEZ:AV0Z10300504 Keywords : hypopituitarism * pituitary adenomas * Leksell gamma knife * irradiation Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 3.423, year: 2011

Stereotactic radiosurgery versus stereotactic radiotherapy for patients with vestibular schwannoma: a Leksell Gamma Knife Society 2000 debate.

Science.gov (United States)

Linskey, Mark E

2013-12-01

By definition, the term "radiosurgery" refers to the delivery of a therapeutic radiation dose in a single fraction, not simply the use of stereotaxy. Multiple-fraction delivery is better termed "stereotactic radiotherapy." There are compelling radiobiological principles supporting the biological superiority of single-fraction radiation for achieving an optimal therapeutic response for the slowly proliferating, late-responding, tissue of a schwannoma. It is axiomatic that complication avoidance requires precise three-dimensional conformality between treatment and tumor volumes. This degree of conformality can only be achieved through complex multiisocenter planning. Alternative radiosurgery devices are generally limited to delivering one to four isocenters in a single treatment session. Although they can reproduce dose plans similar in conformality to early gamma knife dose plans by using a similar number of isocenters, they cannot reproduce the conformality of modern gamma knife plans based on magnetic resonance image--targeted localization and five to 30 isocenters. A disturbing trend is developing in which institutions without nongamma knife radiosurgery (GKS) centers are championing and/or shifting to hypofractionated stereotactic radiotherapy for vestibular schwannomas. This trend appears to be driven by a desire to reduce complication rates to compete with modern GKS results by using complex multiisocenter planning. Aggressive advertising and marketing from some of these centers even paradoxically suggests biological superiority of hypofractionation approaches over single-dose radiosurgery for vestibular schwannomas. At the same time these centers continue to use the term radiosurgery to describe their hypofractionated radiotherapy approach in an apparent effort to benefit from a GKS "halo effect." It must be reemphasized that as neurosurgeons our primary duty is to achieve permanent tumor control for our patients and not to eliminate complications at the

Gamma knife radio-surgery in meningiomas: decisive variables in the dose prescription during 14 years

International Nuclear Information System (INIS)

Dominguez O, X.; Diaz A, P.; Toledo B, V.; Zazueta L, F.

2010-09-01

A comparative study is presented among the variables of dose prescription in twelve cases of treated meningiomas from 1997 to 2009 in the Gamma Knife Unit of the Hospital San Javier. An evolution is observed in the definition of the treatment volumes, collimators election and matrix of dose calculation, this evolution has been due so much to the technological advance associated to the image acquisition systems: Computerized axial tomography, Images by magnetic resonance and Angiography by digital subtraction, as well as to the indexes adoption that are used to qualify among different treatment plans. The differences among the analyzed periods demonstrate a favorable learning curve that have influenced contributing to a treatment with a minor irradiated volume due to the application of theoretical models used in this installation, attenuating the risk of peripheral unexpected complications to the treated volume. (Author)

Therapeutic efficacy of stereotactic radiotherapy with gamma knife on early-stage non-small-cell lung cancer and life quality of patients

International Nuclear Information System (INIS)

Ren Zhengting; Cui Di; Ren Ye; Dai Zhuojie; Su Xiaoming; Fan Jingjing; Shen Yulong; Ma Huizhen; Wang Zongye

2012-01-01

Objective: To evaluate the therapeutic efficacy of stereotactic body radiotherapy (SBRT) with gamma knife on stage Ⅰ-Ⅱ non-small-cell lung cancer (NSCLC)and the quality of life of the patients undergoing this therapy. Methods: Twenty NSCLC patients with the median age of 76, 10 at stage Ⅰ and 10 at stage Ⅱ who were unable or unwilling to undergo surgery were given SBRT with gamma knife at the doses of 3-6 Gy in 8-15 fractions,finished within 2 to 3 weeks. The prescription isodose line was 50%,the marginal dose was 39-56 Gy, the central dose was 78-112 Gy, and the total biologically effective dose was 51-83 Gy. The patients were observed after admission and followed up by chest CT 1, 3, 6, and 12 months after treatment until progressive disease or death. EORTC QLQ-LC43 questionnaire was used to investigate the changes in quality of life. Results: The 20 patients were followed up for 24 (12-46) months. At six months after the treatment,the overall response rate was 80%, and the complete response rate was 35%. The 1, 2 and 3-year local control rates were 100%, 95% and 95%, respectively. The 1, 2 and 3-year overall survival rates were 95%, 80% and 50% respectively; The 1, 2, and 3-year progression free survival rates were 85%, 64% and 33%, respectively. The failure rate was 20% and the rate of progress within the planning target volume was 5%. No acute toxicity at grade 3 and over occurred in any patient during the treatment. 15% of the patients developed grade 1-2 radiation pneumonia. Age, gender, pathologic index or not were weakly correlated with the overall survival. The emotional function was improved significantly after treatment (P<0.05), dyspnea and cough were improved at different degrees, however, not significantly. There were no significant changes in the physical function and symptoms, such as fatigue,lack of appetite, insomnia, etc. Conclusions: Significantly improving the motional function and maintaining the quality of life, SBRT with gamma knife

Long-Term Survival after Gamma Knife Radiosurgery in a Case of Recurrent Glioblastoma Multiforme: A Case Report and Review of the Literature

Science.gov (United States)

Thumma, Sudheer R.; Elaimy, Ameer L.; Daines, Nathan; Mackay, Alexander R.; Lamoreaux, Wayne T.; Fairbanks, Robert K.; Demakas, John J.; Cooke, Barton S.; Lee, Christopher M.

2012-01-01

The management of recurrent glioblastoma is highly challenging, and treatment outcomes remain uniformly poor. Glioblastoma is a highly infiltrative tumor, and complete surgical resection of all microscopic extensions cannot be achieved at the time of initial diagnosis, and hence local recurrence is observed in most patients. Gamma Knife radiosurgery has been used to treat these tumor recurrences for select cases and has been successful in prolonging the median survival by 8–12 months on average for select cases. We present the unique case of a 63-year-old male with multiple sequential recurrences of glioblastoma after initial standard treatment with surgery followed by concomitant external beam radiation therapy and chemotherapy (temozolomide). The patient was followed clinically as well as with surveillance MRI scans at every 2-3-month intervals. The patient underwent Gamma Knife radiosurgery three times for 3 separate tumor recurrences, and the patient survived for seven years following the initial diagnosis with this aggressive treatment. The median survival in patients with recurrent glioblastoma is usually 8–12 months after recurrence, and this unique case illustrates that aggressive local therapy can lead to long-term survivors in select situations. We advocate that each patient treatment at the time of recurrence should be tailored to each clinical situation and desire for quality of life and improved longevity. PMID:22548078

Phantom positioning variation in the Gamma Knife® Perfexion dosimetry

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Costa, Nathalia Almeida; Potiens, Maria da Penha Albuquerque [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Saraiva, Crystian [Hospital do Coracao, Sao Paulo, SP (Brazil)

2015-07-01

The use of small volume ionization chamber has become required for the dosimetry of equipment that use small radiation fields. A pinpoint ionization chamber is ideal for the dosimetry of a Gamma Knife® Perfexion (GKP) unit. In this work, this chamber was inserted into the phantom, and measurements were performed with the phantom in different positions, in order to verify if the change in the phantom positioning affects the dosimetry of the GKP. Three different phantom positions were performed. The variation in the result is within the range allowed for the dosimetry of a GKP equipment. (author)

Cavernomas: Outcomes after gamma-knife radiosurgery in Iran

Science.gov (United States)

Azimi, Parisa; Shahzadi, Sohrab; Bitaraf, Mohammad Ali; Azar, Maziar; Alikhani, Mazdak; Zali, Alireza; Sadeghi, Sohrab

2015-01-01

Background: Treatment of cavernomas remains a challenge in surgically inaccessible regions. The purpose of this study was to evaluate outcomes after gamma-knife surgery (GKS) for these patients. Materials and Methods: A retrospective review of 100 patients treated between 2003 and 2011 was conducted in order to evaluate hemorrhage rates, complications, radiation effects after GKS. Dosage at the tumor margin was stratified into two groups: those that received ≤13 Gy; and those who received >13 Gy. The demographic and clinical characteristics of patients including age, gender, and hemorrhage rates were extracted from care records. Results: The median age was 32.5 years (ranging from 15 to 79). 44% were female. The median follow-up time was 42.2 months (ranging from 24 to 90). The median volume of the lesions was 1050.0 mm3 (ranging from 112.0 to 4100.0) before GKS. A reduction of 27.5% in median size of cavernomas was achieved at the last follow-up. There was 12% treatment-related morbidity after GKS. The hemorrhage rate in the first 2 years after GKS was 4.1% and 1.9% thereafter. There was no mortality due to GKS, and 93 patients were alive at the last follow-up. The radiation-related complication developed with marginal dose 13 Gy. Conclusion: The GKS for cavernomas appears to be a safe and beneficial in carefully selected patients. Low-dose GKS may be effective for the management of cavernous malformations. PMID:25767582

Target and peripheral dose from radiation sector motions accompanying couch repositioning of patient coordinates with the Gamma Knife® Perfexion™

International Nuclear Information System (INIS)

Tran, Tuan-Anh; Wu, Vincent; Malhotra, Harish; Steinman, James P.; Prasad, Dheerendra; Podgorsak, Matthew B.

2011-01-01

The GammaPlan ™ treatment planning system (TPS) does not fully account for shutter dose when multiple shots are required to deliver a patient’s treatment. The unaccounted exposures to the target site and its periphery are measured in this study. The collected data are compared to a similar effect from the Gamma Knife ® model 4C. A stereotactic head frame was attached to a Leksell ® 16 cm diameter spherical phantom; using a fiducial-box, CT images of the phantom were acquired and registered in the TPS. Measurements give the relationship of measured dose to the number of repositions with the patient positioning system (PPS) and to the collimator size. An absorbed dose of 10 Gy to the 50% isodose line was prescribed to the target site and all measurements were acquired with an ionization chamber. Measured dose increases with frequency of repositioning and with collimator size. As the radiation sectors transition between the beam on and beam off states, the target receives more shutter dose than the periphery. Shutter doses of 3.53±0.04 and 1.59±0.04 cGy/reposition to the target site are observed for the 16 and 8 mm collimators, respectively. The target periphery receives additional dose that varies depending on its position relative to the target. The radiation sector motions for the Gamma Knife ® Perfexion ™ result in an additional dose due to the shutter effect. The magnitude of this exposure is comparable to that measured for the model 4C

Gamma knife radiosurgery for ten or more brain metastases. Analysis of the whole brain irradiation doses

International Nuclear Information System (INIS)

Nakaya, Kotaro; Hori, Tomokatsu; Izawa, Masahiro; Yamamoto, Masaaki

2002-01-01

Gamma knife (GK) radiosurgery has recently been recognized as the most powerful treatment modality in managing patients with brain metastasis, be they radioresistant or not, solitary or multiple. Very recently, this treatment has been employed in patients with numerous brain metastases, even those with 10 or more lesions. However, cumulative irradiation doses to the whole brain, with such treatment, remain unknown. Since the Gamma Plan ver. 5.10 (ver. 5.30 is presently available, Leksell Gamma Plan) became available in November, 1998, 105 GK procedures have been performed at our two facilities, Tokyo Women's Medical University and Katsuta Hospital Mito Gamma House. The median lesion number was 17, ranging 10-43, and the median cumulative volume of all tumors was 8.72 cm 3 , ranging 0.41-81.41 cm 3 . The selected doses at the lesion periphery ranged 12-25 Gy, the median being 20 Gy. Based on these treatment protocols, the cumulative irradiation dose was computed. The median cumulative irradiation dose to the whole brain was 4.83, ranging 2.16-8.51 Gy: the median integrated dose to the whole brain was 6.2 J, ranging 2.16-11.9 J. The median brain volumes receiving ≥2, ≥5, ≥10, ≥15 and ≥20 Gy were 1105 (range: 410-1501), 309 (46-1247), 64 (13-282), 24 (2-77), and 8 (0-40) cm 3 , respectively. The cumulative whole brain irradiation doses for patients with numerous radiosurgical targets were considered not to exceed the threshold level of normal brain necrosis. (author)

Determination of the 4 mm Gamma Knife helmet relative output factor using a variety of detectors

International Nuclear Information System (INIS)

Tsai, J.-S.; Rivard, Mark J.; Engler, Mark J.; Mignano, John E.; Wazer, David E.; Shucart, William A.

2003-01-01

Though the 4 mm Gamma Knife helmet is used routinely, there is disagreement in the Gamma Knife users community on the value of the 4 mm helmet relative output factor. A range of relative output factors is used, and this variation may impair observations of dose response and optimization of prescribed dose. To study this variation, measurements were performed using the following radiation detectors: silicon diode, diamond detector, radiographic film, radiochromic film, and TLD cubes. To facilitate positioning of the silicon diode and diamond detector, a three-dimensional translation micrometer was used to iteratively determine the position of maximum detector response. Positioning of the films and TLDs was accomplished by manufacturing custom holders for each technique. Results from all five measurement techniques indicate that the 4 mm helmet relative output factor is 0.868±0.014. Within the experimental uncertainties, this value is in good agreement with results obtained by other investigators using diverse techniques

GAFChromic film dosimetry with a flatbed color scanner for Leksell Gamma Knife therapy

International Nuclear Information System (INIS)

Yamauchi, M.; Tominaga, T.; Nakamura, O.; Ueda, R.; Hoshi, M.

2004-01-01

GAFChromic films MD-55-2 have recently been established widely in industrial, scientific, and medical applications as radiation dosimeters. We applied these films to the dosimetry for Leksell Gamma Knife therapy. We used a flatbed image scanner to take digital images of irradiated MD-55-2, and the data were converted to Red, Green and Blue pixel values. The absorbed dose, as derived from the response curve of the Red pixel value, was consistent with the Leksell Gamma Plan dose planning system, for exposures using collimator sizes, 4 mm, 8 mm, and 14 mm. However, the maximum dose in the exposure of the 18 mm collimator was measured to be about 5% smaller than Gamma Plan due to the density effect of the compound material in the head phantom

A follow-up study of cerebral AVMs three years after gamma knife radiosurgery

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Negishi, Masatoshi; Inoue, Hiroshi K.; Hirato, Masafumi; Yokoe, Takao; Iino, Yuichi [Gunma Univ., Maebashi (Japan). School of Medicine; Shibazaki, Tohru

1999-03-01

We analyzed 68 cases with cerebral AVM 3 years after treatment. Total obliteration rates at 1, 2, and 3 years after treatment were 42.5%, 76.1%, and 82.0%, respectively. Four factors: moya type, small volume, deep location and high marginal dose were found to be correlated with total obliteration. So we scored these factor, and categorized them into a grade 0 to 6 Gamma Knife Score (GKS). The total obliteration rate was high in the low GKS group. Hemorrhage occurred in 6 cases with a yearly risk of 2.9%. These cases were relatively large and had high GKS and high Spetzler-Martin grade. Radiation injury occurred in 2 cases. Both cases had edema spreading to white matter and suffered from hemiparesis. Based on these results and our current grading system, our treatment strategy at present is as follows. AVMs with a low GKS had a high obliteration rate and seemed suitable for radiosurgery. Because total obliteration is difficult to achieve in the high grade group, aggressive surgery or endovascular surgery should be considered. (author)

SU-E-T-471: Improvement of Gamma Knife Treatment Planning Through Tumor Control Probability for Metastatic Brain Tumors

Energy Technology Data Exchange (ETDEWEB)

Huang, Z [East Carolina University, Greenville, NC (United States); Feng, Y [East Carolina Univ, Rockville, MD (United States); Lo, S [Case Western Reserve University, Cleveland, OH (United States); Grecula, J [Ohio State University, Columbus, OH (United States); Mayr, N; Yuh, W [University of Washington, Seattle, WA (United States)

2015-06-15

Purpose: The dose–volume histogram (DVH) has been normally accepted as a tool for treatment plan evaluation. However, spatial information is lacking in DVH. As a supplement to the DVH in three-dimensional treatment planning, the differential DVH (DDVH) provides the spatial variation, the size and magnitude of the different dose regions within a region of interest, which can be incorporated into tumor control probability model. This study was to provide a method in evaluating and improving Gamma Knife treatment planning. Methods: 10 patients with brain metastases from different primary tumors including melanoma (#1,#4,#5, #10), breast cancer (#2), prostate cancer (#3) and lung cancer (#6–9) were analyzed. By using Leksell GammaPlan software, two plans were prepared for each patient. Special attention was given to the DDVHs that were different for different plans and were used for a comparison between two plans. Dose distribution inside target and tumor control probability (TCP) based on DDVH were calculated, where cell density and radiobiological parameters were adopted from literature. The plans were compared based on DVH, DDVH and TCP. Results: Using DVH, the coverage and selectivity were the same between plans for 10 patients. DDVH were different between two plans for each patient. The paired t-test showed no significant difference in TCP between the two plans. For brain metastases from melanoma (#1, #4–5), breast cancer (#2) and lung cancer (#6–8), the difference in TCP was less than 5%. But the difference in TCP was about 6.5% for patient #3 with the metastasis from prostate cancer, 10.1% and 178.7% for two patients (#9–10) with metastasis from lung cancer. Conclusion: Although DVH provides average dose–volume information, DDVH provides differential dose– volume information with respect to different regions inside the tumor. TCP provides radiobiological information and adds additional information on improving treatment planning as well as adaptive

SU-E-T-471: Improvement of Gamma Knife Treatment Planning Through Tumor Control Probability for Metastatic Brain Tumors

International Nuclear Information System (INIS)

Huang, Z; Feng, Y; Lo, S; Grecula, J; Mayr, N; Yuh, W

2015-01-01

Purpose: The dose–volume histogram (DVH) has been normally accepted as a tool for treatment plan evaluation. However, spatial information is lacking in DVH. As a supplement to the DVH in three-dimensional treatment planning, the differential DVH (DDVH) provides the spatial variation, the size and magnitude of the different dose regions within a region of interest, which can be incorporated into tumor control probability model. This study was to provide a method in evaluating and improving Gamma Knife treatment planning. Methods: 10 patients with brain metastases from different primary tumors including melanoma (#1,#4,#5, #10), breast cancer (#2), prostate cancer (#3) and lung cancer (#6–9) were analyzed. By using Leksell GammaPlan software, two plans were prepared for each patient. Special attention was given to the DDVHs that were different for different plans and were used for a comparison between two plans. Dose distribution inside target and tumor control probability (TCP) based on DDVH were calculated, where cell density and radiobiological parameters were adopted from literature. The plans were compared based on DVH, DDVH and TCP. Results: Using DVH, the coverage and selectivity were the same between plans for 10 patients. DDVH were different between two plans for each patient. The paired t-test showed no significant difference in TCP between the two plans. For brain metastases from melanoma (#1, #4–5), breast cancer (#2) and lung cancer (#6–8), the difference in TCP was less than 5%. But the difference in TCP was about 6.5% for patient #3 with the metastasis from prostate cancer, 10.1% and 178.7% for two patients (#9–10) with metastasis from lung cancer. Conclusion: Although DVH provides average dose–volume information, DDVH provides differential dose– volume information with respect to different regions inside the tumor. TCP provides radiobiological information and adds additional information on improving treatment planning as well as adaptive

Gamma Knife radiosurgery for vestibular schwannoma: case report and review of the literature.

Science.gov (United States)

Arthurs, Benjamin J; Lamoreaux, Wayne T; Giddings, Neil A; Fairbanks, Robert K; Mackay, Alexander R; Demakas, John J; Cooke, Barton S; Lee, Christopher M

2009-12-18

Vestibular schwannomas, also called acoustic neuromas, are benign tumors of the vestibulocochlear nerve. Patients with these tumours almost always present with signs of hearing loss, and many also experience tinnitus, vertigo, and equilibrium problems. Following diagnosis with contrast enhanced MRI, patients may choose to observe the tumour with subsequent scans or seek active treatment in the form of microsurgery, radiosurgery, or radiotherapy. Unfortunately, definitive guidelines for treating vestibular schwannomas are lacking, because of insufficient evidence comparing the outcomes of therapeutic modalities.We present a contemporary case report, describing the finding of a vestibular schwannoma in a patient who presented with dizziness and a "clicking" sensation in the ear, but no hearing deficit. Audible clicking is a symptom that, to our knowledge, has not been associated with vestibular schwannoma in the literature. We discuss the diagnosis and patient's decision-making process, which led to treatment with Gamma Knife radiosurgery. Treatment resulted in an excellent radiographic response and complete hearing preservation. This case highlights an atypical presentation of vestibular schwannoma, associated with audible "clicks" and normal hearing. We also provide a concise review of the available literature on modern vestibular schwannoma treatment, which may be useful in guiding treatment decisions.

Seizure control of Gamma Knife radiosurgery for non-hemorrhagic arteriovenous malformations

International Nuclear Information System (INIS)

Lim, Y.J.; Lee, C.Y.; Koh, J.S.; Kim, T.S.; Kim, G.K.; Rhee, B.A.

2006-01-01

Although radiosurgery has been found to be a safe and effective alternative treatment, seizure outcome of arteriovenous malformation (AVM) radiosurgery has not been documented in detail. We report the effect of Gamma Knife radiosurgery (GKRS) on seizures associated with AVMs and discuss the various factors that influence the prognosis. Between 1992 and 2001 246 patients were treated with GKRS for AVMs at Kyung-Hee medical center. Forty five (17.0 %) patients have non-hemorrhagic AVMs and presenting symptom was seizure. Two patients of all were excluded from this study due to loss of follow-up after radiosurgery. In this study retrospective analysis of clinical characteristics, radiological findings, radiosurgical seizure outcome were performed. There were 32 male and 11 female with age ranging from 10 to 74 years (mean 35 years). Type of seizure included: general tonic clonic (n = 28); focal motor or sensory (n = 7): partial complex (n = 8). The location of AVM was temporal (n = 18); frontal (n = 9): deep seated (n =7): parietal (n = 5); occipital (n = 4). Follow-up period was from 8 months to 12 years (mean 46 months). Mean volume was 6.2 cc (2.7-20), mean marginal and maximal dosage was 19.5 (17-26) and 36.6 Gy (13-50). During follow-up after radiosurgical treatment, 23 (53.5 %) of 43 patients were seizure-free. 10 (23.3 %) had significant improvement, were unchanged in 8 (18.6 %) and aggravated in 2 (4.6 %) patients. In 33 patients, follow-up angiography or MRI was performed. Complete obliteration was achieved in 16 (49.0 %) patients, partial obliteration in 13 (39.0 %). Four were unchanged (12.0 %). Of 33 patients with follow-up performed, 26 were followed for over 2 years. Eleven (84.6 %) of 13 patients with complete obliteration were seizure-free (p < 0.005). Four (36.3 %) of 13 with partial obliteration and unchanged remained seizure-free. Fifteen patients had experienced intractable seizure before radiosurgery. After radiosurgery, seizures disappeared in 8

Impact of Millimeter-Level Margins on Peripheral Normal Brain Sparing for Gamma Knife Radiosurgery

International Nuclear Information System (INIS)

Ma, Lijun; Sahgal, Arjun; Larson, David A.; Pinnaduwage, Dilini; Fogh, Shannon; Barani, Igor; Nakamura, Jean; McDermott, Michael; Sneed, Penny

2014-01-01

Purpose: To investigate how millimeter-level margins beyond the gross tumor volume (GTV) impact peripheral normal brain tissue sparing for Gamma Knife radiosurgery. Methods and Materials: A mathematical formula was derived to predict the peripheral isodose volume, such as the 12-Gy isodose volume, with increasing margins by millimeters. The empirical parameters of the formula were derived from a cohort of brain tumor and surgical tumor resection cavity cases (n=15) treated with the Gamma Knife Perfexion. This was done by first adding margins from 0.5 to 3.0 mm to each individual target and then creating for each expanded target a series of treatment plans of nearly identical quality as the original plan. Finally, the formula was integrated with a published logistic regression model to estimate the treatment-induced complication rate for stereotactic radiosurgery when millimeter-level margins are added. Results: Confirmatory correlation between the nominal target radius (ie, R T ) and commonly used maximum target size was found for the studied cases, except for a few outliers. The peripheral isodose volume such as the 12-Gy volume was found to increase exponentially with increasing Δ/R T , where Δ is the margin size. Such a curve fitted the data (logarithmic regression, R 2 >0.99), and the 12-Gy isodose volume was shown to increase steeply with a 0.5- to 3.0-mm margin applied to a target. For example, a 2-mm margin on average resulted in an increase of 55% ± 16% in the 12-Gy volume; this corresponded to an increase in the symptomatic necrosis rate of 6% to 25%, depending on the Δ/R T values for the target. Conclusions: Millimeter-level margins beyond the GTV significantly impact peripheral normal brain sparing and should be applied with caution. Our model provides a rapid estimate of such an effect, particularly for large and/or irregularly shaped targets

Clinical Realization of Sector Beam Intensity Modulation for Gamma Knife Radiosurgery: A Pilot Treatment Planning Study

International Nuclear Information System (INIS)

Ma, Lijun; Mason, Erica; Sneed, Penny K.; McDermott, Michael; Polishchuk, Alexei; Larson, David A.; Sahgal, Arjun

2015-01-01

Purpose: To demonstrate the clinical feasibility and potential benefits of sector beam intensity modulation (SBIM) specific to Gamma Knife stereotactic radiosurgery (GKSRS). Methods and Materials: SBIM is based on modulating the confocal beam intensities from individual sectors surrounding an isocenter in a nearly 2π geometry. This is in contrast to conventional GKSRS delivery, in which the beam intensities from each sector are restricted to be either 0% or 100% and must be identical for any given isocenter. We developed a SBIM solution based on available clinical planning tools, and we tested it on a cohort of 12 clinical cases as a proof of concept study. The SBIM treatment plans were compared with the original clinically delivered treatment plans to determine dosimetric differences. The goal was to investigate whether SBIM would improve the dose conformity for these treatment plans without prohibitively lengthening the treatment time. Results: A SBIM technique was developed. On average, SBIM improved the Paddick conformity index (PCI) versus the clinically delivered plans (clinical plan PCI = 0.68 ± 0.11 vs SBIM plan PCI = 0.74 ± 0.10, P=.002; 2-tailed paired t test). The SBIM plans also resulted in nearly identical target volume coverage (mean, 97 ± 2%), total beam-on times (clinical plan 58.4 ± 38.9 minutes vs SBIM 63.5 ± 44.7 minutes, P=.057), and gradient indices (clinical plan 3.03 ± 0.27 vs SBIM 3.06 ± 0.29, P=.44) versus the original clinical plans. Conclusion: The SBIM method is clinically feasible with potential dosimetric gains when compared with conventional GKSRS

Evaluation of a synthetic single-crystal diamond detector for relative dosimetry on the Leksell Gamma Knife Perfexion radiosurgery system

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Mancosu, Pietro; Reggiori, Giacomo, E-mail: giacomo.reggiori@humanitas.it; Stravato, Antonella; Gaudino, Anna; Lobefalo, Francesca; Palumbo, Valentina; Tomatis, Stefano [Physics Service of Radiation Oncology Department, Clinical and Research Center, Rozzano, Milan 20098 (Italy); Navarria, Piera; Ascolese, Anna; Scorsetti, Marta [Radiation Oncology Department, Humanitas Clinical and Research Center, Rozzano, Milan 20089 (Italy); Picozzi, Piero [Neurosurgery Department, Humanitas Clinical and Research Center, Rozzano, Milan 20089 (Italy); Marinelli, Marco; Verona-Rinati, Gianluca [Dipartimento di Ingegneria Industriale, Università di Roma Tor Vergata, Roma 00133 (Italy)

2015-09-15

Purpose: To evaluate the new commercial PTW-60019 synthetic single-crystal microDiamond detector (PTW, Freiburg, Germany) for relative dosimetry measurements on a clinical Leksell Gamma Knife Perfexion radiosurgery system. Methods: Detector output ratios (DORs) for 4 and 8 mm beams were measured using a microDiamond (PTW-60019), a stereotactic unshielded diode [IBA stereotactic field detector (SFD)], a shielded diode (IBA photon field detector), and GafChromic EBT3 films. Both parallel and transversal acquisition directions were considered for PTW-60019 measurements. Measured DORs were compared to the new output factor reference values for Gamma Knife Perfexion (0.814 and 0.900 for 4 and 8 mm, respectively). Profiles in the three directions were also measured for the 4 mm beam to evaluate full width at half maximum (FWHM) and penumbra and to compare them with the corresponding Leksell GammaPlan profiles. Results: FWHM and penumbra for PTW-60019 differed from the calculated values by less than 0.2 and 0.3 mm, for the parallel and transversal acquisitions, respectively. GafChromic films showed FWHM and penumbra within 0.1 mm. The output ratio obtained with the PTW-60019 for the 4 mm field was 1.6% greater in transverse direction compared to the nominal value. Comparable differences up to 0.8% and 1.0% for, respectively, GafChromic films and SFD were found. Conclusions: The microDiamond PTW-60019 is a suitable detector for commissioning and routine use of Gamma Knife with good agreement of both DORs and profiles in the three directions.

Evaluation of a synthetic single-crystal diamond detector for relative dosimetry on the Leksell Gamma Knife Perfexion radiosurgery system

International Nuclear Information System (INIS)

Mancosu, Pietro; Reggiori, Giacomo; Stravato, Antonella; Gaudino, Anna; Lobefalo, Francesca; Palumbo, Valentina; Tomatis, Stefano; Navarria, Piera; Ascolese, Anna; Scorsetti, Marta; Picozzi, Piero; Marinelli, Marco; Verona-Rinati, Gianluca

2015-01-01

Purpose: To evaluate the new commercial PTW-60019 synthetic single-crystal microDiamond detector (PTW, Freiburg, Germany) for relative dosimetry measurements on a clinical Leksell Gamma Knife Perfexion radiosurgery system. Methods: Detector output ratios (DORs) for 4 and 8 mm beams were measured using a microDiamond (PTW-60019), a stereotactic unshielded diode [IBA stereotactic field detector (SFD)], a shielded diode (IBA photon field detector), and GafChromic EBT3 films. Both parallel and transversal acquisition directions were considered for PTW-60019 measurements. Measured DORs were compared to the new output factor reference values for Gamma Knife Perfexion (0.814 and 0.900 for 4 and 8 mm, respectively). Profiles in the three directions were also measured for the 4 mm beam to evaluate full width at half maximum (FWHM) and penumbra and to compare them with the corresponding Leksell GammaPlan profiles. Results: FWHM and penumbra for PTW-60019 differed from the calculated values by less than 0.2 and 0.3 mm, for the parallel and transversal acquisitions, respectively. GafChromic films showed FWHM and penumbra within 0.1 mm. The output ratio obtained with the PTW-60019 for the 4 mm field was 1.6% greater in transverse direction compared to the nominal value. Comparable differences up to 0.8% and 1.0% for, respectively, GafChromic films and SFD were found. Conclusions: The microDiamond PTW-60019 is a suitable detector for commissioning and routine use of Gamma Knife with good agreement of both DORs and profiles in the three directions

Study of the heterogeneities effect in the dose distributions of Leksell Gamma Knife (R), through Monte Carlo simulation; Estudio del efecto de las heterogeneidades en las distribuciones de dosis del Leksell GammaKnife (R), mediante simulacion Monte Carlo

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Rojas C, E.L. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Al-Dweri, F.M.O.; Lallena R, A.M. [Universidad de Granada, Granada (Spain)]. e-mail: elrc@nuclear.inin.mx

2005-07-01

In this work they are studied, by means of Monte Carlo simulation, the effects that take place in the dose profiles that are obtained with the Leksell Gamma Knife (R), when they are kept in account heterogeneities. The considered heterogeneities simulate the skull and the spaces of air that are in the head, like they can be the nasal breasts or the auditory conduits. The calculations were made using the Monte Carlo Penelope simulation code (v. 2003). The geometry of each one of the 201 sources that this instrument is composed, as well as of the corresponding channels of collimation of the Gamma Knife (R), it was described by means of a simplified model of geometry that has been recently studied. The obtained results when they are kept in mind the heterogeneities they present non worthless differences regarding those obtained when those are not considered. These differences are maximum in the proximities of the interfaces among different materials. (Author)

RT-23THE ROLE OF GAMMA KNIFE RADIOSURGERY IN THE TREATMENT FOR PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMAS

Science.gov (United States)

Mori, Kanji; Chiba, Yasuyoshi; Toyota, Shingo; Kumagai, Tetsuya; Yamamoto, Shota; Sugano, Hirohumi; Taki, Takuyu

2014-01-01

To evaluate the role of gamma knife (GK) as a treatment modality for primary central nervous system lymphomas (PCNSL), we reviewed PCNSL patients who were treated with GK between November 2004 and May 2014, retrospectively. There were 29 cases (13 males and 16 females, ranged from 33 years old to 91 years old) with 210 treated lesions. Marginal dose was from 12Gy to 18 Gy. One hundred and nineteen lesions of 23 cases could be accessed and all of them showed partial response or complete response. In seven cases, GK was performed at initial treatment, in 18 cases at recurrence, and in four cases at both. Median age of initial treatment group were significantly higher than that of recurred group (77.8 y.o. and 63.6 y.o., p = 0.00268). Two cases of initial treatment group and 16 cases of recurrent group were treated with whole brain radiation therapy (WBRT). GK after first relapse, progression free survival more than six months were obtained for six cases (33.3%), and four of them were free from additional therapy more than one year. Otherwise, thirteen cases (59.1%) received GK repeatedly (2-6 times, median = 3), and interval between each therapy was from 22 to 513 days (median = 93days). We confirmed that GK has high potential for local control. And it was supposed that GK was used as an alternative to WBRT at initial treatment for elderly, or selected to recurrent cases after WBRT. These results showed the role of GK in the treatment for PCNSL is palliative care, now in Japan. But it is clear that there exist patients who can live longer without WBRT by GK. We conclude that GK will become to play a more positive role by modifying its timing and modalities used together.

Surgery for acoustic neurinoma treated by gamma-knife radiosurgery. A case report

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Tokuda, Kentaro; Inamura, Takanori; Uesaka, Toshio; Matsushima, Toshio; Fukui, Masashi [Kyushu Univ., Fukuoka (Japan). Graduate School of Medical Science; Kenai, Hiroyuki; Karashima, Atushi

2001-08-01

A 52-year-old woman had a history of left hearing loss for 5 years. An acoustic neurinoma with 3.2 cm in diameter was diagnosed and treated with gamma-knife radiosurgery (19 Gy of marginal dose) 1 year and 4 months ago. She developed headache, nausea, and visual disturbance 1 month prior to admission. Slight left facial palsy appeared after radiosurgery. Magnetic resonance imaging demonstrated the tumor with central necrosis in the left cerebellopontine angle cistern, increasing in size to 3.5 cm in diameter, and hydrocephalus. Tumor removal was performed incompletely, because of the fibrous appearance of the tumor and severe adherence with the surrounding cerebellar tissue. Facial palsy did not worsen after surgery. Since the hydrocephalus was not resolved, a right ventriculo-peritoneal shunt was inserted. The clinical course in this case suggests that tumor removal followed by radiosurgery was an approximately effective treatment for large acoustic neurinoma. (author)

Gamma knife radiosurgery for Cushing's disease and Nelson's syndrome.

Science.gov (United States)

Marek, Josef; Ježková, Jana; Hána, Václav; Kršek, Michal; Liščák, Roman; Vladyka, Vilibald; Pecen, Ladislav

2015-06-01

This paper presents our 18 years of experience in treating ACTH secreting adenomas (Cushing's disease and Nelson's syndrome) using the Leksell gamma knife (LGK) irradiation. Twenty-six patients with Cushing's disease were followed-up after LGK irradiation for 48-216 months (median 78 months). Seventeen patients had undergone previous surgery, in nine patients LGK irradiation was the primary therapy. Furthermore, 14 patients with Nelson's syndrome were followed-up for 30-204 months (median 144 months). LGK treatment resulted in hormonal normalization in 80.7 % of patients with Cushing's disease. Time to normalization was 6-54 months (median 30 months). The volume of the adenoma decreased in 92.3% (in 30.7% disappeared completely). There was no recurrence of the disease. In all 14 patients with Nelson's syndrome ACTH levels decreased (in two patients fully normalized) their ACTH levels. When checked up 5-10 years after irradiation regrowth of the adenoma was only detected in one patient (9.1%), in 27.3% adenoma volume remained unchanged, in 45.4% adenoma volume decreased and in 18.2% adenoma completely disappeared. Hypopituitarism did not develop in any patient where the critical dose to the pituitary and distal infundibulum was respected. LGK radiation represents an effective and well-tolerated option for the treatment of patients with Cushing's disease after unsuccessful surgery and may be valuable even as a primary treatment in patients who are not suitable for, or refuse, surgery. In the case of Nelson's syndrome it is possible to impede tumorous growth and control the size of the adenoma in almost all patients.

Clinical Outcome in Gamma Knife Radiosurgery for Metastatic Brain Tumors from the Primary Breast Cancer : Prognostic Factors in Local Treatment Failure and Survival

OpenAIRE

Choi, Seung Won; Kwon, Do Hoon; Kim, Chang Jin

2013-01-01

Objective Brain metastases in primary breast cancer patients are considerable sources of morbidity and mortality. Gamma knife radiosurgery (GKRS) has gained popularity as an up-front therapy in treating such metastases over traditional radiation therapy due to better neurocognitive function preservation. The aim of this study was to clarify the prognostic factors for local tumor control and survival in radiosurgery for brain metastases from primary breast cancer. Methods From March 2001 to Ma...

Gamma knife radiosurgery for glomus jugulare tumors: therapeutic advantages of minimalism in the skull base.

Science.gov (United States)

Sharma, Manish S; Gupta, A; Kale, S S; Agrawal, D; Mahapatra, A K; Sharma, B S

2008-01-01

Glomus jugulare (GJ) tumors are paragangliomas found in the region of the jugular foramen. Surgery with/without embolization and conventional radiotherapy has been the traditional management option. To analyze the efficacy of gamma knife radiosurgery (GKS) as a primary or an adjunctive form of therapy. A retrospective analysis of patients who received GKS at a tertiary neurosurgical center was performed. Of the 1601 patients who underwent GKS from 1997 to 2006, 24 patients with GJ underwent 25 procedures. The average age of the cohort was 46.6 years (range, 22-76 years) and the male to female ratio was 1:2. The most common neurological deficit was IX, X, XI cranial nerve paresis (15/24). Fifteen patients received primary GKS. Mean tumor size was 8.7 cc (range 1.1-17.2 cc). The coverage achieved was 93.1% (range 90-97%) using a mean tumor margin dose of 16.4 Gy (range 12-25 Gy) at a mean isodose of 49.5% (range 45-50%). Thirteen patients (six primary and seven secondary) were available for follow-up at a median interval of 24 months (range seven to 48 months). The average tumor size was 7.9 cc (range 1.1-17.2 cc). Using a mean tumor margin dose of 16.3 Gy (range 12-20 Gy) 93.6% coverage (range 91-97%) was achieved. Six patients improved clinically. A single patient developed transient trigeminal neuralgia. Magnetic resonance imaging follow-up was available for 10 patients; seven recorded a decrease in size. There was no tumor progression. Gamma knife radiosurgery is a safe and effective primary and secondary modality of treatment for GJ.

Iridium-Knife: Another knife in radiation oncology.

Science.gov (United States)

Milickovic, Natasa; Tselis, Nikolaos; Karagiannis, Efstratios; Ferentinos, Konstantinos; Zamboglou, Nikolaos

Intratarget dose escalation with superior conformity is a defining feature of three-dimensional (3D) iridium-192 ( 192 Ir) high-dose-rate (HDR) brachytherapy (BRT). In this study, we analyzed the dosimetric characteristics of interstitial 192 Ir HDR BRT for intrathoracic and cerebral malignancies. We examined the dose gradient sharpness of HDR BRT compared with that of linear accelerator-based stereotactic radiosurgery and stereotactic body radiation therapy, usually called X-Knife, to demonstrate that it may as well be called a Knife. Treatment plans for 10 patients with recurrent glioblastoma multiforme or intrathoracic malignancies, five of each entity, treated with X-Knife (stereotactic radiosurgery for glioblastoma multiforme and stereotactic body radiation therapy for intrathoracic malignancies) were replanned for simulated HDR BRT. For 3D BRT planning, we used identical structure sets and dose prescription as for the X-Knife planning. The indices for qualitative treatment plan analysis encompassed planning target volume coverage, conformity, dose falloff gradient, and the maximum dose-volume limits to different organs at risk. Volume coverage in HDR plans was comparable to that calculated for X-Knife plans with no statistically significant difference in terms of conformity. The dose falloff gradient-sharpness-of the HDR plans was considerably steeper compared with the X-Knife plans. Both 3D 192 Ir HDR BRT and X-Knife are effective means for intratarget dose escalation with HDR BRT achieving at least equal conformity and a steeper dose falloff at the target volume margin. In this sense, it can reasonably be argued that 3D 192 Ir HDR BRT deserves also to be called a Knife, namely Iridium-Knife. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Present situation and prospect of gamma knife radiosurgery for functional brain disorders

International Nuclear Information System (INIS)

Zhang Yongquan; Zhao Xianjun; Liu Wenli

2002-01-01

With the evolution of imaging technology in the past two decades, currently anatomic targets including the trigeminal nerve (for trigeminal neuralgia), the thalamus (for tremor or pain), the cingulate gyrus, anterior internal capsule or amygdala (for pain or psychiatric illness), the globus pallidum (for symptoms of Parkinson's disease), and the hippocampus (for epilepsy) can be precisely located with computerized tomography, magnetic resonance image, single photon emission computerized tomography and positron emission tomography; stereotactic radiosurgery gradually tends to perfection. Gamma knife therapy for nervous functional disorders has become the focus of interest in clinical study

SU-C-201-06: Small Field Correction Factors for the MicroDiamond Detector in the Gamma Knife-Model C Derived Using Monte Carlo Methods

International Nuclear Information System (INIS)

Barrett, J C; Knill, C

2016-01-01

Purpose: To determine small field correction factors for PTW’s microDiamond detector in Elekta’s Gamma Knife Model-C unit. These factors allow the microDiamond to be used in QA measurements of output factors in the Gamma Knife Model-C; additionally, the results also contribute to the discussion on the water equivalence of the relatively-new microDiamond detector and its overall effectiveness in small field applications. Methods: The small field correction factors were calculated as k correction factors according to the Alfonso formalism. An MC model of the Gamma Knife and microDiamond was built with the EGSnrc code system, using BEAMnrc and DOSRZnrc user codes. Validation of the model was accomplished by simulating field output factors and measurement ratios for an available ABS plastic phantom and then comparing simulated results to film measurements, detector measurements, and treatment planning system (TPS) data. Once validated, the final k factors were determined by applying the model to a more waterlike solid water phantom. Results: During validation, all MC methods agreed with experiment within the stated uncertainties: MC determined field output factors agreed within 0.6% of the TPS and 1.4% of film; and MC simulated measurement ratios matched physically measured ratios within 1%. The final k correction factors for the PTW microDiamond in the solid water phantom approached unity to within 0.4%±1.7% for all the helmet sizes except the 4 mm; the 4 mm helmet size over-responded by 3.2%±1.7%, resulting in a k factor of 0.969. Conclusion: Similar to what has been found in the Gamma Knife Perfexion, the PTW microDiamond requires little to no corrections except for the smallest 4 mm field. The over-response can be corrected via the Alfonso formalism using the correction factors determined in this work. Using the MC calculated correction factors, the PTW microDiamond detector is an effective dosimeter in all available helmet sizes. The authors would like to

SU-C-201-06: Small Field Correction Factors for the MicroDiamond Detector in the Gamma Knife-Model C Derived Using Monte Carlo Methods

Energy Technology Data Exchange (ETDEWEB)

Barrett, J C [Wayne State University, Detroit, MI (United States); Karmanos Cancer Institute McLaren-Macomb, Clinton Township, MI (United States); Knill, C [Wayne State University, Detroit, MI (United States); Beaumont Hospital, Canton, MI (United States)

2016-06-15

Purpose: To determine small field correction factors for PTW’s microDiamond detector in Elekta’s Gamma Knife Model-C unit. These factors allow the microDiamond to be used in QA measurements of output factors in the Gamma Knife Model-C; additionally, the results also contribute to the discussion on the water equivalence of the relatively-new microDiamond detector and its overall effectiveness in small field applications. Methods: The small field correction factors were calculated as k correction factors according to the Alfonso formalism. An MC model of the Gamma Knife and microDiamond was built with the EGSnrc code system, using BEAMnrc and DOSRZnrc user codes. Validation of the model was accomplished by simulating field output factors and measurement ratios for an available ABS plastic phantom and then comparing simulated results to film measurements, detector measurements, and treatment planning system (TPS) data. Once validated, the final k factors were determined by applying the model to a more waterlike solid water phantom. Results: During validation, all MC methods agreed with experiment within the stated uncertainties: MC determined field output factors agreed within 0.6% of the TPS and 1.4% of film; and MC simulated measurement ratios matched physically measured ratios within 1%. The final k correction factors for the PTW microDiamond in the solid water phantom approached unity to within 0.4%±1.7% for all the helmet sizes except the 4 mm; the 4 mm helmet size over-responded by 3.2%±1.7%, resulting in a k factor of 0.969. Conclusion: Similar to what has been found in the Gamma Knife Perfexion, the PTW microDiamond requires little to no corrections except for the smallest 4 mm field. The over-response can be corrected via the Alfonso formalism using the correction factors determined in this work. Using the MC calculated correction factors, the PTW microDiamond detector is an effective dosimeter in all available helmet sizes. The authors would like to

Radiation tolerance of normal temporal bone structures: implications for gamma knife stereotactic radiosurgery

International Nuclear Information System (INIS)

Linskey, Mark E.; Johnstone, Peter A.

2003-01-01

Popular current thought states that hearing loss and facial weakness after radiosurgery of vestibular schwannomas is a function of cranial nerve damage. Although this may be true in some cases, the middle and inner ear contain rich networks of other sensitive structures that are at risk after radiotherapy and that may contribute to toxicity afterward. We reviewed the limited reported data regarding radiation tolerance of external, middle, and inner ear structures, and perspectives for therapy with gamma knife stereotactic radiosurgery are addressed

Gamma Knife radiosurgery for vestibular schwannoma: case report and review of the literature

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Fairbanks Robert K

2009-12-01

Full Text Available Abstract Vestibular schwannomas, also called acoustic neuromas, are benign tumors of the vestibulocochlear nerve. Patients with these tumours almost always present with signs of hearing loss, and many also experience tinnitus, vertigo, and equilibrium problems. Following diagnosis with contrast enhanced MRI, patients may choose to observe the tumour with subsequent scans or seek active treatment in the form of microsurgery, radiosurgery, or radiotherapy. Unfortunately, definitive guidelines for treating vestibular schwannomas are lacking, because of insufficient evidence comparing the outcomes of therapeutic modalities. We present a contemporary case report, describing the finding of a vestibular schwannoma in a patient who presented with dizziness and a "clicking" sensation in the ear, but no hearing deficit. Audible clicking is a symptom that, to our knowledge, has not been associated with vestibular schwannoma in the literature. We discuss the diagnosis and patient's decision-making process, which led to treatment with Gamma Knife radiosurgery. Treatment resulted in an excellent radiographic response and complete hearing preservation. This case highlights an atypical presentation of vestibular schwannoma, associated with audible "clicks" and normal hearing. We also provide a concise review of the available literature on modern vestibular schwannoma treatment, which may be useful in guiding treatment decisions.

Radiosurgical lesion of the rat hippocampus using the Leksell gamma knife: relation between radiation dose and functional and structural damage

Czech Academy of Sciences Publication Activity Database

Liščák, R.; Vladyka, V.; Novotný Jr., J.; Brožek, G.; Náměstková, Kateřina; Mareš, V.; Hájek, M.; Herynek, V.; Syková, Eva

2002-01-01

Roč. 97, č. 5 (2002), s. 666-673 ISSN 0022-3085 Institutional research plan: CEZ:AV0Z5039906 Keywords : radiosurgery * Leksell gamma knife Subject RIV: FH - Neurology Impact factor: 2.626, year: 2002

Gamma Knife Radiosurgery Treatment for Metastatic Melanoma of the Trigeminal Nerve and Brainstem: A Case Report and a Review of the Literature

Science.gov (United States)

Peterson, Halloran E.; Larson, Erik W.; Fairbanks, Robert K.; Lamoreaux, Wayne T.; Mackay, Alexander R.; Call, Jason A.; Demakas, John J.; Cooke, Barton S.; Lee, Christopher M.

2013-01-01

Objective and Importance. Brainstem metastases (BSMs) are uncommon but serious complications of some cancers. They cause significant neurological deficit, and options for treatment are limited. Stereotactic radiosurgery (SRS) has been shown to be a safe and effective treatment for BSMs that prolongs survival and can preserve or in some cases improve neurological function. This case illustrates the use of repeated SRS, specifically Gamma Knife radiosurgery (GKRS) for management of a unique brainstem metastasis. Clinical Presentation. This patient presented 5 years after the removal of a lentigo maligna melanoma from her left cheek with left sided facial numbness and paresthesias with no reported facial weakness. Initial MRI revealed a mass on the left trigeminal nerve that appeared to be a trigeminal schwannoma. Intervention. After only limited response to the first GKRS treatment, a biopsy of the tumor revealed it to be metastatic melanoma, not schwannoma. Over the next two years, the patient would receive 3 more GKRS treatments. These procedures were effective in controlling growth in the treated areas, and the patient has maintained a good quality of life. Conclusion. GKRS has proven in this case to be effective in limiting the growth of this metastatic melanoma without acute adverse effects. PMID:24194991

Evaluation of Different Score Index for Predicting Prognosis in Gamma Knife Radiosurgical Treatment for Brain Metastasis

International Nuclear Information System (INIS)

Franzin, Alberto; Snider, Silvia; Picozzi, Piero; Bolognesi, Angelo; Serra, Carlo; Vimercati, Alberto; Passarin, Olga; Mortini, Pietro

2009-01-01

Purpose: To assess the utility of the Radiation Therapy Oncology Group Recursive Partitioning Analysis (RPA) and Score Index for Radiosurgery (SIR) stratification systems in predicting survival in patients with brain metastasis treated with Gamma Knife radiosurgery (GKRS). Methods and Materials: A total of 185 patients were included in the study. Patients were stratified according to RPA and SIR classes. The RPA and SIR classes, age, Karnofsky Performance Status (KPS), and systemic disease were correlated with survival. Results: Five patients were lost to follow-up. Median survival in patients in RPA Class 1 (30 patients) was 17 months; in Class 2 (140 patients), 10 months; and in Class 3 (10 patients), 3 months. Median survival in patients in SIR Class 1 (30 patients) was 3 months; in Class 2 (135 patients), 8 months; and in Class 3 (15 patients), 20 months. In univariate testing, age younger than 65 years (p = 0.0004), KPS higher than 70 (p = 0.0001), RPA class (p = 0.0078), SIR class (p = 0.0002), and control of the primary tumor (p = 0.02) were significantly associated with improved outcome. In multivariate analysis, KPS (p < 0.0001), SIR class (p = 0.0008), and RPA class (p = 0.03) had statistical value. Conclusions: This study supports the use of GKRS as a single-treatment modality in this selected group of patients. Stratification systems are useful in the estimation of patient eligibility for GKRS. A second-line treatment was necessary in 30% of patients to achieve distal or local brain control. This strategy is useful to control brain metastasis in long-surviving patients.

Study of the heterogeneities effect in the dose distributions of Leksell Gamma Knife (R), through Monte Carlo simulation

International Nuclear Information System (INIS)

Rojas C, E.L.; Al-Dweri, F.M.O.; Lallena R, A.M.

2005-01-01

In this work they are studied, by means of Monte Carlo simulation, the effects that take place in the dose profiles that are obtained with the Leksell Gamma Knife (R), when they are kept in account heterogeneities. The considered heterogeneities simulate the skull and the spaces of air that are in the head, like they can be the nasal breasts or the auditory conduits. The calculations were made using the Monte Carlo Penelope simulation code (v. 2003). The geometry of each one of the 201 sources that this instrument is composed, as well as of the corresponding channels of collimation of the Gamma Knife (R), it was described by means of a simplified model of geometry that has been recently studied. The obtained results when they are kept in mind the heterogeneities they present non worthless differences regarding those obtained when those are not considered. These differences are maximum in the proximities of the interfaces among different materials. (Author)

Delayed radiation necrosis 7 years after gamma knife surgery for arteriovenous malformation. Two case reports

International Nuclear Information System (INIS)

Oyoshi, Tatsuki; Yatsushiro, Kazutaka; Arita, Kazunori; Hirahara, Kazuho; Uetsuhara, Koichi

2010-01-01

A 44-year-old woman and a 55-year-old woman were treated with gamma knife surgery (GKS) for occipital arteriovenous malformation (AVM). Angiography confirmed complete nidus obliterations 2 years after GKS. However, both patients complained of chronic headache and visual symptoms from around 7 years after GKS. Magnetic resonance imaging showed round masses with or without cystic change surrounded by large areas of brain edema. Angiography also showed complete obliteration of AVM at this time. Extended corticosteroid treatment failed to control the edema. Both patients underwent total surgical removal of the mass. Visual disturbance and chronic headache improved postoperatively and the brain edema rapidly subsided. The histological diagnosis was radiation necrosis in both cases, attributed to the low conformity index and large 12-Gy volume due to usage of a large collimator for GKS. These cases of delayed radiation necrosis after GKS suggest that surgical removal of necrotic lesions is necessary for radiation necrosis intractable to medical treatment. (author)

Leksell gamma knife lesioning of the rat hippocampus: the relationship between radiation dose and functional and structural damage

Czech Academy of Sciences Publication Activity Database

Liščák, R.; Vladyka, V.; Novotný ml., J.; Brožek, G.; Náměstková, K.; Mareš, Vladislav; Herynek, V.; Jirák, D.; Hájek, M.; Syková, E.

2002-01-01

Roč. 97, Suppl. 5 (2002), s. 666-673 ISSN 0022-3085 R&D Projects: GA MZd NF5161 Institutional research plan: CEZ:AV0Z5011922 Keywords : Leksell gamma knife * rats * memory Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 2.626, year: 2002

SU-F-T-370: A Fast Monte Carlo Dose Engine for Gamma Knife

Energy Technology Data Exchange (ETDEWEB)

Song, T; Zhou, L [Southern Medical University, Guangzhou, Guangdong (China); Li, Y [Beihang University, Beijing, Beijing (China)

2016-06-15

Purpose: To develop a fast Monte Carlo dose calculation algorithm for Gamma Knife. Methods: To make the simulation more efficient, we implemented the track repeating technique on GPU. We first use EGSnrc to pre-calculate the photon and secondary electron tracks in water from two mono-energy photons of 60Co. The total photon mean free paths for different materials and energies are obtained from NIST. During simulation, each entire photon track was first loaded to shared memory for each block, the incident original photon was then splitted to Nthread sub-photons, each thread transport one sub-photon, the Russian roulette technique was applied for scattered and bremsstrahlung photons. The resultant electrons from photon interactions are simulated by repeating the recorded electron tracks. The electron step length is stretched/shrunk proportionally based on the local density and stopping power ratios of the local material. Energy deposition in a voxel is proportional to the fraction of the equivalent step length in that voxel. To evaluate its accuracy, dose deposition in a 300mm*300mm*300mm water phantom is calculated, and compared to EGSnrc results. Results: Both PDD and OAR showed great agreements (within 0.5%) between our dose engine result and the EGSnrc result. It only takes less than 1 min for every simulation, being reduced up to ∼40 times compared to EGSnrc simulations. Conclusion: We have successfully developed a fast Monte Carlo dose engine for Gamma Knife.

A treatment strategy for arteriovenous malformations of the brain based on results of gamma knife surgery experienced between 1991 and 1995

International Nuclear Information System (INIS)

Inoue, Hiroshi K.; Nagaseki, Yoshishige; Nishi, Hideo; Sanada, Tomoyuki; Tachikawa, Yuichi; Nishimatsu, Terutaka; Ohye, Chihiro; Andou, Yoshitaka; Naitou, Isao

2001-01-01

We investigated a treatment strategy for arteriovenous malformations (AVMs) of the brain based on results of 107 patients treated with Gamma Knife (GK) surgery between 1991 and 1995. Total obliteration was obtained in 80.5%. The obliteration rate was 82.1% in Grade 3 of Spetzler-Martin scale, 75.0% in Grade 4, 50.0% in Grade 5, and 66.7% in Grade 6. The obliteration rate of slow and low flow AVMs (moya type) within 12 months (65.5%) was significantly higher than that of rapid and/or high flow AVMs (shunt, mixed type). Six patients had bleeding 7 to 42 months after GK surgery. The annual rate of bleeding in accumulated years was 2.3%. Adverse effects appeared in 2 (1.9%) of 107 patients, and both patients had AVMs in the internal capsule. We concluded that microsurgery is recommended for AVMs operable without morbidity, and GK surgery is recommended for AVMs in functional areas, and that intravascular embolization is required for large, rapid and/or high flow AVMs, especially those with hemorrhagic risk factors. (author)

The clinical research on fractionated irradiation treatment with X knife in patients of PD

International Nuclear Information System (INIS)

Wei Pengxiang; Chen Xu; Ai Quanshan; Xia Jiyong; Yang Jiongda; Chen Binghuan

2003-01-01

Objective: To explore X knife treatment methods and to seek a new effective way for PD therapy. Methods: Sixteen patients of PD were treated by performing VIM with 2 times of X knife fractionated irradiation (interval, 24 h) to a total dose of 140 Gy, and 8 patients of PD were treated by performing VIM with 3 times of X knife fractionated irradiation (interval, 24 h) to a total of dose of 165 Gy. Results: During 3-24 months follow-up after X knife treatment, tremor was stopped in 19 patients and was relived significantly in 5 patients. Rigidity and bradykinesia of PD were relieved slightly. No complications were observed. Conclusion: To perform VIM with X knife fractionated irradiation can be safely and effectively used to treat PD. The tremor of PD can be relieved slightly

Dose distribution close to metal implants in Gamma Knife Radiosurgery: A Monte Carlo study

International Nuclear Information System (INIS)

Cheung, Joel Y.C.; Yu, K.N.; Chan, Josie F.K.; Ho, Robert T.K.; Yu, C.P.

2003-01-01

Materials with high atomic numbers favor the occurrence of the photoelectric effect when they are irradiated with gamma rays. Therefore, the photoelectric effects of metal implants within the target regions in Gamma Knife Radiosurgery are worth studying. In the present work, Monte Carlo simulations using EGS4 were employed to investigate the resulting dose enhancements. A dose enhancement as high as 10% was observed close to a platinum implant along the x and y axes, while no significant dose enhancements were observed for silver, stainless steel 301, and titanium ones. A dose enhancement as high as 20% was observed close to the platinum implant along the z axis at the superior position of the metal-phantom interface and was 10% higher for other metal implants

Management of brain metastasis in a patient with advanced epithelial ovarian carcinoma by gamma-knife radiosurgery.

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Nikolaoul, Marinos; Stamenković, Srdjan; Stergiou, Christos; Skarleas, Christos; Torrens, Michael

2015-01-01

Brain metastases from epithelial ovarian cancer (EOC) are rare events. We present a rare case of single ovarian cancer metastasis to the brain treated with gamma-knife radiosurgery (GKRS). A 65-year-old woman with advanced EOC presented with severe neurologic symptoms. A single brain metastasis of 3.2 cm with surrounding edema in the left parietal lobe was detected by brain magnetic resonance imaging (MRI) scan during the work-up. The decision to perform GKRS was due to a surgical inaccessibility of intracranial lesion. Twelve weeks after the procedure, the MRI scan showed reduction in the diameter of brain metastasis and surrounding edema and the patient returned to good mental and motor performance.The patient survived for 22 months following treatment and died from a progressive intra-abdominal disease. Prognosis of ovarian cancer patients with brain metastases is generally poor regardless of treatment. Our case shows that GKRS as primary treatment modality for the control of ovarian cancer metastases to the brain was effective and can be considered as a treatment of choice if international selection criteria are followed.

Gamma knife thalamotomy for Parkinson's tremor: A 5-year experience

International Nuclear Information System (INIS)

Duma, Christopher M.; Jacques, Deane B.; Kopyov, Oleg V.; Mark, Rufus J.; Copcutt, Brian G.

1996-01-01

Purpose: Elderly, high-risk surgical patients, may be unfit for radiofrequency thalamotomy for Parkinson's tremor. We have performed gamma knife radiosurgery in this select patient population, in lieu of open surgery, in an attempt at amelioration of disabling tremor. Materials and Methods: Radiosurgical nucleus ventralis intermedalis thalamotomy using gamma unit technique was performed on 38 patients (median age, 72 years; range: 50-88 years) over a period of 5 years. A median dose of 155 Gy (range: 110-160 Gy) was delivered using a single 4-mm collimator to 40 nuclei (2 patients underwent bilateral thalamotomy) using only anatomical atlas landmarks. The number of males and females were evenly divided, and their ages ranged from 50 to 88 years (median: 72 years). Two-thirds of the patients underwent left thalamotomy for right-sided trmor. Patients were followed-up for a median of 14 months (range: 6 to 43 months). Independent neurological evaluation of tremor as well as subjective patient evaluation were based on a 4-tiered scale: no improvement, mild improvement (0-33% effect), good improvement (33-66% effect), and excellent improvement (66-100%). Results: Eight thalamotomies (20%) failed, four (10%) gave mild improvement, and 28 (70%) gave good to excellent improvement of tremor (median time of onset of improvement was 3 months; range: 1-11 months). In 12 patients (32%) the tremor was eliminated completely. Concordance between independent neurologist evaluation and that of the patient was significant (p<0.001). Two patients in the failure group had an initial transient improvement. Two patients who underwent unilateral thalamotomy had bilateral improvement of their tremor. A permanent 5-6 mm lesion was seen on all follow-up MRIs and there were no radiological complications. A worsening of hand strength was seen in only patient. Conclusion: The safety and efficacy of gamma unit radiosurgical thalamotomy is on par with that of radiofrequency thalamotomy, and in a

[Treatment of trigger finger with located needle knife].

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Zhang, Qi-Feng; Yang, Jiang; Xi, Sheng-Hua

2016-07-25

To investigate the clinical effects of located needle knife in the treatment of trigger finger. The clinical data of 133 patients(145 fingers) with trigger finger underwent treatment with located needle knife from September 2010 to March 2014 were retrospectively analyzed. There were 37 males(40 fingers) and 96 females (105 fingers), aged from 18 to 71 years old with a mean of 51.8 years. Course of disease was from 1 to 19 months with an average of 8.2 months. Affected fingers included 82 thumbs, 12 index fingers, 11 middle fingers, 36 ring fingers, and 4 little fingers. According to the standard of Quinnell grade, 42 fingers were grade III, 92 fingers were grade IV, and 11 fingers were grade V. Firstly the double pipe gab was put into the distal edge of hypertrophic tendon sheath, then small knife needle was used to release the sheath proximally along the tendon line direction. The informations of wound healing and nerve injury, postoperative finger function, finger pain at 6 months were observed. The operation time was from 8 to 25 min with an average of 9.8 min. All the patients were followed up from 6 to 26 months with an average of 12.5 months. No complications such as the wound inflammation and seepage, vascular or nerve injuries were found. According to the standard of Quinnell grade, 123 fingers got excellent results, 15 good, 7 poor. It's a good choice to treat trigger finger with located needle knife in advantage of minimal invasion, simple safe operation, and it should be promoted in clinic.

Communicating Hydrocephalus Associated with Intracranial Schwannoma Treated by Gamma Knife Radiosurgery.

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Park, Chang Kyu; Lee, Sung Ho; Choi, Man Kyu; Choi, Seok Keun; Park, Bong Jin; Lim, Young Jin

2016-05-01

Gamma knife radiosurgery (GKRS) has been established as an effective and safe treatment for intracranial schwannoma. However, serious complications can occur after GKRS, including hydrocephalus. The pathophysiology and risk factors of this disorder are not yet fully understood. The objective of the study was to assess potential risk factors for hydrocephalus after GKRS. We retrospectively reviewed the medical radiosurgical records of 244 patients who underwent GKRS to treat intracranial schwannoma. The following parameters were analyzed as potential risk factors for hydrocephalus after GKRS: age, sex, target volume, irradiation dose, prior tumor resection, treatment technique, and tumor enhancement pattern. The tumor enhancement pattern was divided into 2 groups: group A (homogeneous enhancement) and group B (heterogeneous or rim enhancement). Of the 244 patients, 14 of them (5.7%) developed communicating hydrocephalus. Communicating hydrocephalus occurred within 2 years after GKRS in most patients (92.8%). No significant association was observed between any of the parameters investigated and the development of hydrocephalus, with the exception of tumor enhancement pattern. Group B exhibited a statistically significant difference by univariate analysis (P = 0.002); this difference was also significant by multivariate analysis (P = 0.006). Because hydrocephalus is curable, patients should be closely monitored for the development of this disorder after GKRS. In particular, patients with intracranial schwannomas with irregular enhancement patterns or cysts should be meticulously observed. Copyright © 2015 Elsevier Inc. All rights reserved.

Novel biomarker identification using metabolomic profiling to differentiate radiation necrosis and recurrent tumor following Gamma Knife radiosurgery.

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Lu, Alex Y; Turban, Jack L; Damisah, Eyiyemisi C; Li, Jie; Alomari, Ahmed K; Eid, Tore; Vortmeyer, Alexander O; Chiang, Veronica L

2017-08-01

OBJECTIVE Following an initial response of brain metastases to Gamma Knife radiosurgery, regrowth of the enhancing lesion as detected on MRI may represent either radiation necrosis (a treatment-related inflammatory change) or recurrent tumor. Differentiation of radiation necrosis from tumor is vital for management decision making but remains difficult by imaging alone. In this study, gas chromatography with time-of-flight mass spectrometry (GC-TOF) was used to identify differential metabolite profiles of the 2 tissue types obtained by surgical biopsy to find potential targets for noninvasive imaging. METHODS Specimens of pure radiation necrosis and pure tumor obtained from patient brain biopsies were flash-frozen and validated histologically. These formalin-free tissue samples were then analyzed using GC-TOF. The metabolite profiles of radiation necrosis and tumor samples were compared using multivariate and univariate statistical analysis. Statistical significance was defined as p ≤ 0.05. RESULTS For the metabolic profiling, GC-TOF was performed on 7 samples of radiation necrosis and 7 samples of tumor. Of the 141 metabolites identified, 17 (12.1%) were found to be statistically significantly different between comparison groups. Of these metabolites, 6 were increased in tumor, and 11 were increased in radiation necrosis. An unsupervised hierarchical clustering analysis found that tumor had elevated levels of metabolites associated with energy metabolism, whereas radiation necrosis had elevated levels of metabolites that were fatty acids and antioxidants/cofactors. CONCLUSIONS To the authors' knowledge, this is the first tissue-based metabolomics study of radiation necrosis and tumor. Radiation necrosis and recurrent tumor following Gamma Knife radiosurgery for brain metastases have unique metabolite profiles that may be targeted in the future to develop noninvasive metabolic imaging techniques.

Feasibility of Multiple Repeat Gamma Knife Radiosurgeries for Trigeminal Neuralgia: A Case Report and Review of the Literature

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Jones, Guy C.; Elaimy, Ameer L.; Demakas, John J.; Jiang, Hansi; Lamoreaux, Wayne T.; Fairbanks, Robert K.; Mackay, Alexander R.; Cooke, Barton S.; Lee, Christopher M.

2011-01-01

Treatment options for trigeminal neuralgia (TN) must be customized for the individual patient, and physicians must be aware of the medical, surgical, and radiation treatment modalities to prescribe optimal treatment courses for specific patients. The following case illustrates the potential for gamma knife radiosurgery (GKRS) to be repeated multiple times for the purpose of achieving facial pain control in cases of TN that have been refractory to other medical and surgical options, as well as prior GKRS. The patient described failed to achieve pain control with initial GKRS, as well as medical and surgical treatments, but experienced significant pain relief for a period of time with a second GKRS procedure and later underwent a third procedure. Only a small subset of patients have reportedly undergone more than two GKRS for TN; thus, further research and long-term clinical followup will be valuable in determining its usefulness in specific clinical situations. PMID:21904556

Repeated transsphenoidal surgery or gamma knife radiosurgery in recurrent cushing disease after transsphenoidal surgery.

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Bodaghabadi, Mohammad; Riazi, Hooman; Aran, Shima; Bitaraf, Mohammad Ali; Alikhani, Mazdak; Alahverdi, Mahmud; Mohamadi, Masoumeh; Shalileh, Keivan; Azar, Maziar

2014-03-01

This study compared Gamma knife radiosurgery (GKRS) and repeated transsphenoidal adenomectomy (TSA) to find the best approach for recurrence of Cushing disease (CD) after unsuccessful first TSA. Fifty-two patients with relapse of CD after TSA were enrolled and randomly underwent a second surgery or GKRS as the next therapeutic approach. They were followed for a mean period of 3.05 ± 0.8 years by physical examination and hormone measurement as well as magnetic resonance imaging. No significant difference was observed in sex ratio, mean age, adenoma type, follow-up duration, and initial hormone level between the two groups. No significant relationship was found between preoperative 24-hour free urine cortisol and disease-free months or tumor volume among both groups. Our statistical analysis showed higher recurrence-free interval in the GKRS group compared with TSA group. With longer recurrence-free interval, GKRS could be considered a good treatment alternative to repeated TSA in recurrent CD. Georg Thieme Verlag KG Stuttgart · New York.

Evolution of gamma knife capsulotomy for intractable obsessive-compulsive disorder.

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Miguel, Euripedes C; Lopes, Antonio C; McLaughlin, Nicole C R; Norén, Georg; Gentil, André F; Hamani, Clement; Shavitt, Roseli G; Batistuzzo, Marcelo C; Vattimo, Edoardo F Q; Canteras, Miguel; De Salles, Antonio; Gorgulho, Alessandra; Salvajoli, João Victor; Fonoff, Erich Talamoni; Paddick, Ian; Hoexter, Marcelo Q; Lindquist, Christer; Haber, Suzanne N; Greenberg, Benjamin D; Sheth, Sameer A

2018-05-09

For more than half a century, stereotactic neurosurgical procedures have been available to treat patients with severe, debilitating symptoms of obsessive-compulsive disorder (OCD) that have proven refractory to extensive, appropriate pharmacological, and psychological treatment. Although reliable predictors of outcome remain elusive, the establishment of narrower selection criteria for neurosurgical candidacy, together with a better understanding of the functional neuroanatomy implicated in OCD, has resulted in improved clinical efficacy for an array of ablative and non-ablative intervention techniques targeting the cingulum, internal capsule, and other limbic regions. It was against this backdrop that gamma knife capsulotomy (GKC) for OCD was developed. In this paper, we review the history of this stereotactic radiosurgical procedure, from its inception to recent advances. We perform a systematic review of the existing literature and also provide a narrative account of the evolution of the procedure, detailing how the procedure has changed over time, and has been shaped by forces of evidence and innovation. As the procedure has evolved and adverse events have decreased considerably, favorable response rates have remained attainable for approximately one-half to two-thirds of individuals treated at experienced centers. A reduction in obsessive-compulsive symptom severity may result not only from direct modulation of OCD neural pathways but also from enhanced efficacy of pharmacological and psychological therapies working in a synergistic fashion with GKC. Possible complications include frontal lobe edema and even the rare formation of delayed radionecrotic cysts. These adverse events have become much less common with new radiation dose and targeting strategies. Detailed neuropsychological assessments from recent studies suggest that cognitive function is not impaired, and in some domains may even improve following treatment. We conclude this review with

Clinical outcomes following salvage Gamma Knife radiosurgery for recurrent glioblastoma

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Larson, Erik W; Peterson, Halloran E; Lamoreaux, Wayne T; MacKay, Alexander R; Fairbanks, Robert K; Call, Jason A; Carlson, Jonathan D; Ling, Benjamin C; Demakas, John J; Cooke, Barton S; Lee, Christopher M

2014-01-01

Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor with a survival prognosis of 14-16 mo for the highest functioning patients. Despite aggressive, multimodal upfront therapies, the majority of GBMs will recur in approximately six months. Salvage therapy options for recurrent GBM (rGBM) are an area of intense research. This study compares recent survival and quality of life outcomes following Gamma Knife radiosurgery (GKRS) salvage therapy. Following a PubMed search for studies using GKRS as salvage therapy for malignant gliomas, nine articles from 2005 to July 2013 were identified which evaluated rGBM treatment. In this review, we compare Overall survival following diagnosis, Overall survival following salvage treatment, Progression-free survival, Time to recurrence, Local tumor control, and adverse radiation effects. This report discusses results for rGBM patient populations alone, not for mixed populations with other tumor histology grades. All nine studies reported median overall survival rates (from diagnosis, range: 16.7-33.2 mo; from salvage, range: 9-17.9 mo). Three studies identified median progression-free survival (range: 4.6-14.9 mo). Two showed median time to recurrence of GBM. Two discussed local tumor control. Six studies reported adverse radiation effects (range: 0%-46% of patients). The greatest survival advantages were seen in patients who received GKRS salvage along with other treatments, like resection or bevacizumab, suggesting that appropriately tailored multimodal therapy should be considered with each rGBM patient. However, there needs to be a randomized clinical trial to test GKRS for rGBM before the possibility of selection bias can be dismissed. PMID:24829861

Therapeutic Effect of Gamma Knife Radiosurgery for Multiple Brain Metastases

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Lee, Chul-Kyu; Lee, Sang Ryul; Cho, Jin Mo; Yang, Kyung Ah

2011-01-01

Objective The aim of this study is to evaluate the therapeutic effects of gamma knife radiosurgery (GKRS) in patients with multiple brain metastases and to investigate prognostic factors related to treatment outcome. Methods We retrospectively reviewed clinico-radiological and dosimetric data of 36 patients with 4-14 brain metastases who underwent GKRS for 264 lesions between August 2008 and April 2011. The most common primary tumor site was the lung (n=22), followed by breast (n=7). At GKRS, the median Karnofsky performance scale score was 90 and the mean tumor volume was 1.2 cc (0.002-12.6). The mean prescription dose of 17.8 Gy was delivered to the mean 61.1% isodose line. Among 264 metastases, 175 lesions were assessed for treatment response by at least one imaging follow-up. Results The overall median survival after GKRS was 9.1±1.7 months. Among various factors, primary tumor control was a significant prognostic factor (11.1±1.3 months vs. 3.3±2.4 months, p=0.031). The calculated local tumor control rate at 6 and 9 months after GKRS were 87.9% and 84.2%, respectively. Paddick's conformity index (>0.75) was significantly related to local tumor control. The actuarial peritumoral edema reduction rate was 22.4% at 6 months. Conclusion According to our results, GKRS can provide beneficial effect for the patients with multiple (4 or more) brain metastases, when systemic cancer is controlled. And, careful dosimetry is essential for local tumor control. Therefore, GKRS can be considered as one of the treatment modalities for multiple brain metastase. PMID:22102945

Long-Term Survival of a Patient with Brainstem and Recurrent Brain Metastasis from Stage IV Nonsmall Cell Lung Cancer Treated with Multiple Gamma Knife Radiosurgeries and Craniotomies: A Case Report and Review of the Literature

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Lamm, Andrew F.; Elaimy, Ameer L.; Mackay, Alexander R.; Fairbanks, Robert K.; Demakas, John J.; Cooke, Barton S.; Lee, Christopher M.; Taylor, Blake S.; Lamoreaux, Wayne T.

2012-01-01

The prognosis of patients diagnosed with stage IV nonsmall cell lung cancer that have brain and brainstem metastasis is very poor, with less than a third surviving a year past their initial date of diagnosis. We present the rare case of a 57-year-old man who is a long-term survivor of brainstem and recurrent brain metastasis, after aggressive treatment. He is now five and a half years out from diagnosis and continues to live a highly functional life without evidence of disease. Four separate Gamma Knife stereotactic radiosurgeries in conjunction with two craniotomies were utilized since his initial diagnosis to treat recurrent brain metastasis while chemoradiation therapy and thoracic surgery were used to treat his primary disease in the right upper lung. In his situation, Gamma Knife radiosurgery proved to be a valuable, safe, and effective tool for the treatment of multiply recurrent brain metastases within critical normal structures. PMID:23056973

EGSnrc calculated and MRI-polymer gel dosimeter measured dose distribution of gamma knife in presence of inhomogeneities

International Nuclear Information System (INIS)

Allahverdi Pourfallah, T.; Allahverdi, M.; Riahi Alam, N.; Ay, M.; Zahmatkesh, M.; Ibbott, J.S.

2008-01-01

Stereotactic gamma-knife radiosurgery plays an important role in managing small intracranial brain lesions. Currently, polymer gel dosimetry is still the only dosimetry method for directly measuring three-dimensional dose distributions. polymer gel dosimeters are tissue equivalent and can act as a phantom material. In this study effects of inhomogeneities on those distributions have been investigated using both EGSnrc calculation and PAGAT polymer gel dosimeter. (author)

The development of 60Co γ knife therapy sources

International Nuclear Information System (INIS)

Wu Rihua; Li Xingyi; Wu Guihua; Xia Bing; Zhang Jirong; Chen Tieguang

2001-01-01

60 Co γ gamma knife source is a kernel unit of γ knife therapy equipment. It has small active core, high specific activity, narrow half dark area, best focus form, long use period. The research of 60 Co γ knife sources are presented. Specifications of γ knife sources, technical parameters, safety performance, structure feature, procedure and quality control during research are discussed. 60 Co γ source consists of high specific activity cobalt pellets and double stainless steel sealed by argon arc welding. Its safety performance, surface contamination and leakage testing meet the requirements of GB 4075 and GB 4076

Gamma Knife radiosurgery for brain metastases from pulmonary large cell neuroendocrine carcinoma: a Japanese multi-institutional cooperative study (JLGK1401).

Science.gov (United States)

Kawabe, Takuya; Yamamoto, Masaaki; Sato, Yasunori; Yomo, Shoji; Kondoh, Takeshi; Nagano, Osamu; Serizawa, Toru; Tsugawa, Takahiko; Okamoto, Hisayo; Akabane, Atsuya; Aita, Kazuyasu; Sato, Manabu; Jokura, Hidefumi; Kawagishi, Jun; Shuto, Takashi; Kawai, Hideya; Moriki, Akihito; Kenai, Hiroyuki; Iwai, Yoshiyasu; Gondo, Masazumi; Hasegawa, Toshinori; Yasuda, Soichiro; Kikuchi, Yasuhiro; Nagatomo, Yasushi; Watanabe, Shinya; Hashimoto, Naoya

2016-12-01

OBJECTIVE In 1999, the World Health Organization categorized large cell neuroendocrine carcinoma (LCNEC) of the lung as a variant of large cell carcinoma, and LCNEC now accounts for 3% of all lung cancers. Although LCNEC is categorized among the non-small cell lung cancers, its biological behavior has recently been suggested to be very similar to that of a small cell pulmonary malignancy. The clinical outcome for patients with LCNEC is generally poor, and the optimal treatment for this malignancy has not yet been established. Little information is available regarding management of LCNEC patients with brain metastases (METs). This study aimed to evaluate the efficacy of Gamma Knife radiosurgery (GKRS) for patients with brain METs from LCNEC. METHODS The Japanese Leksell Gamma Knife Society planned this retrospective study in which 21 Gamma Knife centers in Japan participated. Data from 101 patients were reviewed for this study. Most of the patients with LCNEC were men (80%), and the mean age was 67 years (range 39-84 years). Primary lung tumors were reported as well controlled in one-third of the patients. More than half of the patients had extracranial METs. Brain metastasis and lung cancer had been detected simultaneously in 25% of the patients. Before GKRS, brain METs had manifested with neurological symptoms in 37 patients. Additionally, prior to GKRS, resection was performed in 17 patients and radiation therapy in 10. A small cell lung carcinoma-based chemotherapy regimen was chosen for 48 patients. The median lesion number was 3 (range 1-33). The median cumulative tumor volume was 3.5 cm 3 , and the median radiation dose was 20.0 Gy. For statistical analysis, the standard Kaplan-Meier method was used to determine post-GKRS survival. Competing risk analysis was applied to estimate GKRS cumulative incidences of maintenance of neurological function and death, local recurrence, appearance of new lesions, and complications. RESULTS The overall median survival time

Gamma knife radiosurgery for arteriovenous malformations located in the sensorimotor cortex

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Yamanaka, Kazuhiro; Iwai, Yoshiyasu; Komiyama, Masaki; Nakajima, Hideki; Yasui, Toshihiro; Nishikawa, Misao; Sakamoto, Hiroaki; Morikawa, Toshie [Osaka City General Hospital (Japan)

2002-05-01

The goal of this study was to define treatment results of gamma knife radiosurgery (GKS) for arteriovenous malformation (AVM) located in the sensorimotor cortex. We analyzed 27 patients followed up for at least 12 months. The onset of AVM was convulsion 10, clinical hemorrhage 7, neurological deficits 4, and headache 3. The mean diameter of the AVM nidus was 22.2 mm (range 8.5-33.6 mm) and mean volume was 7.4 ml (range 0.32-19.9 ml). According to the Spetzler-Martin scale, the AVMs were Grade II in 13, Grade III in 10, and Grade IV in 4 of the patients. GKS was performed with a mean dose of 19.0 Gy (range 14-25 Gy) to the margin of the nidus. The mean follow-up period was 29 months (range 12-72 months). Six AVMs showed complete obliteration angiographically and 5 AVMs showed obliteration on magnetic resonance image. Sixteen AVMs showed nidus shrinkage. Eight (53%) of 15 patients followed up for more than 24 months showed obliteration. Complications consisted of 32 (11.5%) of 27 patients with evidence of radiation injury to the brain parenchyma. Symptoms of slight hemiparesis resolved completely in all patients within several months. (author)

Management of brain metastasis in a patient with advanced epithelial ovarian carcinoma by gamma-knife radiosurgery

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Nikolaou Marinos

2015-01-01

Full Text Available Introduction. Brain metastases from epithelial ovarian cancer (EOC are rare events. We present a rare case of single ovarian cancer metastasis to the brain treated with gamma-knife radiosurgery (GKRS. Case Outline. A 65-year-old woman with advanced EOC presented with severe neurologic symptoms. A single brain metastasis of 3.2 cm with surrounding edema in the left parietal lobe was detected by brain magnetic resonance imaging (MRI scan during the work-up. The decision to perform GKRS was due to a surgical inaccessibility of intracranial lesion. Twelve weeks after the procedure, the MRI scan showed reduction in the diameter of brain metastasis and surrounding edema and the patient returned to good mental and motor performance. The patient survived for 22 months following treatment and died from a progressive intra-abdominal disease. Prognosis of ovarian cancer patients with brain metastases is generally poor regardless of treatment. Conclusion. Our case shows that GKRS as primary treatment modality for the control of ovarian cancer metastases to the brain was effective and can be considered as a treatment of choice if international selection criteria are followed.

Long-Term Results for Trigeminal Schwannomas Treated With Gamma Knife Surgery

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Hasegawa, Toshinori, E-mail: h-toshi@komakihp.gr.jp; Kato, Takenori; Iizuka, Hiroshi; Kida, Yoshihisa

2013-12-01

Purpose: Surgical resection is considered the desirable curative treatment for trigeminal schwannomas. However, complete resection without any complications remains challenging. During the last several decades, stereotactic radiosurgery (SRS) has emerged as a minimally invasive treatment modality. Information regarding long-term outcomes of SRS for patients harboring trigeminal schwannomas is limited because of the rarity of this tumor. The aim of this study was to evaluate long-term tumor control and functional outcomes in patients harboring trigeminal schwannomas treated with SRS, specifically with gamma knife surgery (GKS). Methods and Materials: Fifty-three patients harboring trigeminal schwannomas treated with GKS were evaluated. Of these, 2 patients (4%) had partial irradiation of the tumor, and 34 patients (64%) underwent GKS as the initial treatment. The median tumor volume was 6.0 cm{sup 3}. The median maximum and marginal doses were 28 Gy and 14 Gy, respectively. Results: The median follow-up period was 98 months. On the last follow-up image, 7 patients (13%) had tumor enlargement, including the 2 patients who had partial treatment. Excluding the 2 patients who had partial treatment, the actuarial 5- and 10-year progression-free survival (PFS) rates were 90% and 82%, respectively. Patients with tumors compressing the brainstem with deviation of the fourth ventricle had significantly lower PFS rates. If those patients with tumors compressing the brainstem with deviation of the fourth ventricle are excluded, the actuarial 5- and 10-year PFS rates increased to 95% and 90%, respectively. Ten percent of patients had worsened facial numbness or pain in spite of no tumor progression, indicating adverse radiation effect. Conclusions: GKS can be an acceptable alternative to surgical resection in patients with trigeminal schwannomas. However, large tumors that compress the brainstem with deviation of the fourth ventricle should be surgically removed first and then

Tolerability and efficacy of gamma knife radiosurgery on hepatocellular carcinoma with portal vein tumor thrombosis

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Lu, Xiao-Jie; Dong, Jing; Ji, Li-Juan; Xiao, Li-Xin; Ling, Chang-Quan; Zhou, Jun

2016-01-01

This is a retrospective study on the safety and efficacy of gamma knife radiosurgery (GKR) in treating hepatocellular carcinoma (HCC) with portal vein tumor thrombosis (PVTT). Patients with confirmed HCC and PVTT were allocated into two groups based on the treatments they received (palliative or GKR). A total of 138 patients were included (74 in the palliative group, 64 in GKR group). No significant differences in baseline characteristics existed between the two groups. Treatment-related adverse events (AEs) were recorded and compared between groups. The majority of AEs were mild to moderate and subsided naturally or after medication. There was no AE-induced death. The influences of baseline characteristics and treatment options on patients' OS were analyzed. The median OS of patients in the palliative and GKR group were 3.0 months (95% CI: 2.719-3.281) and 6.1 months (95% CI: 4.706-7.494) respectively (p = 0.003). Multivariate analysis revealed that GKR treatment, performance status 0-1, Child A, smaller tumor diameter and monolobar distribution were significant favorable prognosticators. Subgroup analyses showed OS benefit of GKR regardless of PVTT location (main or branch of PVTT). In conclusion, GKR is well tolerated in selected HCC-PVTT patients and can confer OS benefit, which needs validation in future prospective studies. PMID:26473291

Interfraction and intrafraction performance of the Gamma Knife Extend system for patient positioning and immobilization.

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Schlesinger, David; Xu, Zhiyuan; Taylor, Frances; Yen, Chun-Po; Sheehan, Jason

2012-12-01

The Extend system for the Gamma Knife Perfexion makes possible multifractional Gamma Knife treatments. The Extend system consists of a vacuum-monitored immobilization frame and a positioning measurement system used to determine the location of the patient's head within the frame at the time of simulation imaging and before each treatment fraction. The measurement system consists of a repositioning check tool (RCT), which attaches to the Extend frame, and associated digital measuring gauges. The purpose of this study is to evaluate the performance of the Extend system for patient repositioning before each treatment session (fraction) and patient immobilization between (interfraction) and during (intrafraction) each session in the first 10 patients (36 fractional treatments) treated at the University of Virginia. The RCT was used to acquire a set of reference measurements for each patient position at the time of CT simulation. Repositioning measurements were acquired before each fraction, and the patient position was adjusted until the residual radial difference from the reference position measurements was less than 1 mm. After treatment, patient position measurements were acquired, and the difference between those measurements and the ones obtained for patient position before the fraction was calculated as a measure of immobilization capability. Analysis of patient setup and immobilization performance included calculation of the group mean, standard deviation (SD), and distribution of systematic (components affecting all fractions) and random (per fraction) uncertainty components. Across all patients and fractions, the mean radial setup difference from the reference measurements was 0.64 mm, with an SD of 0.24 mm. The distribution of systematic uncertainty (Σ) was 0.17 mm, and the distribution of random uncertainty (σ) was 0.16 mm. The root mean square (RMS) differences for each plate of the RCT were as follows: right = 0.35 mm; left = 0.41 mm; superior = 0.28 mm

Gamma Knife radiosurgery for treatment of growing vestibular schwannomas in patients with neurofibromatosis Type 2: a matched cohort study with sporadic vestibular schwannomas.

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Kruyt, Ivo J; Verheul, Jeroen B; Hanssens, Patrick E J; Kunst, Henricus P M

2018-01-01

OBJECTIVE Neurofibromatosis Type 2 (NF2) is a tumor syndrome characterized by an autosomal dominant pattern of inheritance. The hallmark of NF2 is the development of bilateral vestibular schwannomas (VSs), generally by 30 years of age. One of the first-line treatment options for small to medium-large VSs is radiosurgery. Although radiosurgery shows excellent results in sporadic VS, its use in NF2-related VS is still a topic of dispute. The aim of this study was to evaluate long-term tumor control, hearing preservation rates, and factors influencing outcome of optimally dosed, contemporary Gamma Knife radiosurgery (GKRS) for growing VSs in patients with NF2 and compare the findings to data obtained in patients with sporadic VS also treated by means of GKRS. METHODS The authors performed a retrospective analysis of 47 growing VSs in 34 NF2 patients who underwent GKRS treatment performed with either the Model C or Perfexion Leksell Gamma Knife, with a median margin dose of 11 Gy. Actuarial tumor control rates were estimated using the Kaplan-Meier method. For patient- and treatment-related factors, a Cox proportional hazards model was used to identify predictors of outcome. Trigeminal, facial, and vestibulocochlear nerve function were assessed before and after treatment. NF2-related VS patients were matched 1:1 with sporadic VS patients who were treated in the same institute, and the same indications for treatment, definitions, and dosimetry were used in order to compare outcomes. RESULTS Actuarial tumor control rates in NF2 patients after 1, 3, 5, and 8 years were 98%, 89%, 87%, and 87%, respectively. Phenotype and tumor volume had significant hazard rates of 0.086 and 22.99, respectively, showing that Feiling-Gardner phenotype and a tumor volume not exceeding 6 cm 3 both were associated with significantly better outcome. Actuarial rates of serviceable hearing preservation after 1, 3, 5, and 7 years were 95%, 82%, 59%, and 33%, respectively. None of the patients

Analysis of 2000 cases treated with gamma knife surgery: validating eligibility criteria for a prospective multi-institutional study of stereotactic radiosurgery alone for treatment of patients with 1-10 brain metastases (JLGK0901) in Japan

Science.gov (United States)

Higuchi, Yoshinori; Nagano, Osamu; Sato, Yasunori; Yamamoto, Masaaki; Ono, Junichi; Saeki, Naokatsu; Miyakawa, Akifumi; Hirai, Tatsuo

2012-01-01

Objective The Japan Leksell Gamma Knife (JLGK) Society has conducted a prospective multi-institute study (JLGK0901, UNIN000001812) for selected patients in order to prove the effectiveness of stereotactic radiosurgery (SRS) alone using the gamma knife (GK) for 1-10 brain lesions. Herein, we verify the validity of 5 major patient selection criteria for the JLGK0901 trial. Materials and Methods Between 1998 and 2010, 2246 consecutive cases with 10352 brain metastases treated with GK were analyzed to determine the validity of the following 5 major JLGK0901 criteria; 1) 1-10 brain lesions, 2) less than 10 cm3 volume of the largest tumor, 3) no more than 15 cm3 total tumor volume, 4) no cerebrospinal fluid (CSF) dissemination, 5) Karnofsky performance status (KPS) score ≥70. Results For cases with >10 brain metastases, salvage treatments for new lesions were needed more frequently. The tumor control rate for lesions larger than 10 cm3 was significantly lower than that of tumors 15 cm3 total tumor volume or positive magnetic resonance imaging findings of CSF were significantly poorer. Outcomes in cases with KPS <70 were significantly poorer in terms of OS. Conclusion Our retrospective results of 2246 GK-treated cases verified the validity of the 5 major JLGK0901 criteria. The inclusion criteria for the JLGK0901 study are appearently good indications for SRS. PMID:29296339

Evaluation of the peripheral dose in stereotactic radiotherapy and radiosurgery treatments

Energy Technology Data Exchange (ETDEWEB)

Di Betta, Erika; Fariselli, Laura; Bergantin, Achille; Locatelli, Federica; Del Vecchio, Antonella; Broggi, Sara; Fumagalli, Maria Luisa [Department of Neurosurgery, Division of Medical Physics, Fondazione IRCCS, Istituto Neurologico C. Besta, 20133 Milano (Italy); Department of Neurosurgery, Division of Radiotherapy, Fondazione IRCCS, Istituto Neurologico C. Besta, 20133 Milano (Italy); CyberKnife Centre, Centro Diagnostico Italiano, 20147 Milano (Italy); Division of Medical Physics, Fondazione IRCCS, Istituto S. Raffaele, 20132 Milano (Italy); Department of Neurosurgery, Division of Medical Physics, Fondazione IRCCS, Istituto Neurologico C. Besta, 20133 Milano (Italy)

2010-07-15

Purpose: The main purpose of this work was to compare peripheral doses absorbed during stereotactic treatment of a brain lesion delivered using different devices. These data were used to estimate the risk of stochastic effects. Methods: Treatment plans were created for an anthropomorphic phantom and delivered using a LINAC with stereotactic cones and a multileaf collimator, a CyberKnife system (before and after a supplemental shielding was applied), a TomoTherapy system, and a Gamma Knife unit. For each treatment, 5 Gy were prescribed to the target. Measurements were performed with thermoluminescent dosimeters inserted roughly in the position of the thyroid, sternum, upper lung, lower lung, and gonads. Results: Mean doses ranged from of 4.1 (Gamma Knife) to 62.8 mGy (LINAC with cones) in the thyroid, from 2.3 (TomoTherapy) to 30 mGy (preshielding CyberKnife) in the sternum, from 1.7 (TomoTherapy) to 20 mGy (preshielding CyberKnife) in the upper part of the lungs, from 0.98 (Gamma Knife) to 15 mGy (preshielding CyberKnife) in the lower part of the lungs, and between 0.3 (Gamma Knife) and 10 mGy (preshielding CyberKnife) in the gonads. Conclusions: The peripheral dose absorbed in the sites of interest with a 5 Gy fraction is low. Although the risk of adverse side effects calculated for 20 Gy delivered in 5 Gy fractions is negligible, in the interest of optimum patient radioprotection, further studies are needed to determine the weight of each contributor to the peripheral dose.

Evaluation of the peripheral dose in stereotactic radiotherapy and radiosurgery treatments

International Nuclear Information System (INIS)

Di Betta, Erika; Fariselli, Laura; Bergantin, Achille; Locatelli, Federica; Del Vecchio, Antonella; Broggi, Sara; Fumagalli, Maria Luisa

2010-01-01

Purpose: The main purpose of this work was to compare peripheral doses absorbed during stereotactic treatment of a brain lesion delivered using different devices. These data were used to estimate the risk of stochastic effects. Methods: Treatment plans were created for an anthropomorphic phantom and delivered using a LINAC with stereotactic cones and a multileaf collimator, a CyberKnife system (before and after a supplemental shielding was applied), a TomoTherapy system, and a Gamma Knife unit. For each treatment, 5 Gy were prescribed to the target. Measurements were performed with thermoluminescent dosimeters inserted roughly in the position of the thyroid, sternum, upper lung, lower lung, and gonads. Results: Mean doses ranged from of 4.1 (Gamma Knife) to 62.8 mGy (LINAC with cones) in the thyroid, from 2.3 (TomoTherapy) to 30 mGy (preshielding CyberKnife) in the sternum, from 1.7 (TomoTherapy) to 20 mGy (preshielding CyberKnife) in the upper part of the lungs, from 0.98 (Gamma Knife) to 15 mGy (preshielding CyberKnife) in the lower part of the lungs, and between 0.3 (Gamma Knife) and 10 mGy (preshielding CyberKnife) in the gonads. Conclusions: The peripheral dose absorbed in the sites of interest with a 5 Gy fraction is low. Although the risk of adverse side effects calculated for 20 Gy delivered in 5 Gy fractions is negligible, in the interest of optimum patient radioprotection, further studies are needed to determine the weight of each contributor to the peripheral dose.

Gamma knife radiosurgery for metastatic brain tumors from lung cancer

Energy Technology Data Exchange (ETDEWEB)

Serizawa, Toru; Ono, Junichi; Iuchi, Toshihiko [Chiba Cardiovascular Center, Ichihara (Japan). Chiba Cancer Center] (and others)

2003-01-01

The purpose of this retrospective study is to evaluate the effectiveness of gamma knife radiosurgery (GKS) alone for metastatic brain tumors from lung cancer. Two hundred thirty-one consecutive patients with metastatic brain tumors from lung cancer filling the following 4 criteria were analyzed for this study; no prior brain tumor treatment, 25 or fewer lesions, a maximum 5 tumors with diameter of 2 cm or more, no surgically inaccessible tumor 3 cm or greater in diameter. According to the same treatment protocol, large tumors ({>=} 3 cm) were surgically removed and all the other small lesions (<3 cm) were treated with GKS. New lesions were treated with repeated GKS. The tumor-progression-free, overall, neurological, lowered-QOL (quality of life)-free and new-lesion-free survivals were calculated with the Kaplan-Meier method. The poor prognostic factors for each survival were also analyzed with the Cox's proportional hazard model. The tumor control rate at 1 year was 96.5%. The estimated median overall survival time was 7.7 months. The first-year survival rates were 83.0% in neurological survival and 76.0% in lowered-QOL-free survival. The new-lesion-free survival at 1 year was 27.9%. Multivariate analysis revealed significant poor prognostic factors for neurological and lowered-QOL-free survivals were carcinomatous meningitis and >10 brain lesions. This study suggests the results of GKS for metastatic brain tumors from lung cancer are quite satisfactory considering prevention of neurological death and maintenance of QOL. But cases with carcinomatous meningitis and/or >10 brain lesions are not good candidates for GKS alone. (author)

Pseudocapsule formation after gamma knife radiosurgery for trigeminal neurinoma. Case report

International Nuclear Information System (INIS)

Akiyama, Takenori; Ikeda, Eiji; Kawase, Takeshi; Yoshida, Kazunari

2005-01-01

A 38-year-old female presented with a trigeminal neurinoma manifesting as left facial paresthesia. The diagnosis was based on magnetic resonance (MR) imaging findings. Gamma knife radiosurgery (GKR) was performed at another hospital at her request. Fifteen months after the GKR, follow-up MR imaging revealed tumor regrowth causing extensive compression of the brainstem, and cyst formation in the tumor. Her clinical symptoms including facial pain and diplopia had worsened, so she was referred to our affiliated hospital for microsurgery. The tumor was totally resected, but the left trigeminal nerve had to be sacrificed because of pseudocapsule formation which covered both the tumor and the trigeminal nerve fibers. The diplopia disappeared, but her facial pain deteriorated after the operation. GKR can induce fibrosis or degenerative change in nearby structures, which may complicate subsequent surgery. (author)

Hearing preservation after low-dose gamma knife radiosurgery of vestibular schwannomas

International Nuclear Information System (INIS)

Horiba, Ayako; Hayashi, Motohiro; Chernov, Mikhail; Kawamata, Takakazu; Okada, Yoshikazu

2016-01-01

The objective of the retrospective study was to evaluate the factors associated with hearing preservation after low-dose Gamma Knife radiosurgery (GKS) of vestibular schwannomas performed according to the modern standards. From January 2005 to September 2010, 141 consecutive patients underwent such treatment in Tokyo Women's Medical University. Mean marginal dose was 11.9 Gy (range, 11-12 Gy). The doses for the brain stem, cranial nerves (V, VII, and VHIII), and cochlea were kept below 14 Gy, 12 Gy, and 4 Gy, respectively. Out of the total cohort, 102 cases with at least 24 months follow-up were analyzed. Within the median follow-up of 56 months (range, 24-99 months) the crude tumor growth control was 92% (94 cases), whereas its actuarial rate at 5 years was 93%. Out of 49 patients with serviceable hearing on the side of the tumor before GKS, 28 (57%) demonstrated its preservation at the time of the last follow-up. No one evaluated factor, namely Gardner-Robertson hearing class before irradiation, Koos tumor stage, extension of the intrameatal part of the neoplasm up to fundus, nerve of tumor origin, presence of cystic changes in the neoplasm, and cochlea dose demonstrated statistically significant association with preservation of the serviceable hearing after radiosurgery. In conclusion, GKS of vestibular schwannomas performed according to the modern standards of treatment permits to preserve serviceable hearing on the side of the tumor in more than half of the patients. The actual causes of hearing deterioration after radiosurgery remain unclear. (author)

Gamma knife radiosurgery for trigeminal neuralgia. Analysis of a multi institutional study

International Nuclear Information System (INIS)

Takanashi, Masami; Ozaki, Yoshimaru; Satou, Kenichi; Oikawa, Mitsuteru; Nakamura, Hirohiko; Fukuoka, Seiji

2013-01-01

A multi-institutional study was conducted to evaluate the results of gamma knife radiosurgery (GKRS) for the treatment of trigeminal neuralgia. Eleven hundred and thirty-five patients at 39 centers were analyzed. Three hundred and sixty-nine patients had undergone percutaneous nerve block and 173 patients had undergone microvascular decompression (MVD) prior to GKRS. GKRS was performed for 69.4% of patients targeted at the nerve root entry zone (REZ) and for 20.4% of patients targeted at the retrogasserian region (RGR). The target dose of the GKRS used in the current study varied from 70 to 90 Gy (mean: 77.8 Gy). The median follow-up period after GKRS was 21.1 months (range 1 to 125 months). Six hundred and eighty-nine patients (66%) responded with excellent or good control (pain free), 157 (15%) obtained fair control (more than 50% relief), and 192 (19%) experienced treatment failure. After 3 years, 64% of cases were pain free and 80% had more than 50% pain relief. After 4 years, 37 patients underwent additional GKRS, 36 MVD and 36 percutaneous nerve block. Tolerable hypoesthesia or paresthesia occurred in 129 patients (11%), whereas bothersome symptoms developed in 8 patients (1%). But no patient developed deafferentation pain. Nine patients (1%) complained of dry eye, but no other abnormalities of the cornea and conjunctiva were found on ophthalmological examination. Higher maximum radiosurgical dose was associated with a significantly greater factor of complete pain relief (p=0.0101). GKRS is a safe and effective alternative treatment for trigeminal neuralgia, and is a minimally invasive treatment. In addition it provided benefit to a patient population unwilling or unable to undergo more invasive surgical approaches. (author)

Long-term outcomes of gamma knife surgery for posterior fossa arteriovenous malformations

International Nuclear Information System (INIS)

Matsunaga, Shigeo; Shuto, Takashi

2014-01-01

The long-term outcomes of gamma knife surgery (GKS) in patients with posterior fossa arteriovenous malformations (AVMs) were retrospectively analyzed in 82 patients followed up for more than 5 years to evaluate the efficacy and safety. The median AVM volume at GKS was 0.95 cm 3 . The prescribed dose to the AVM margin was median 18 Gy with 1-18 isocenters. The actual complete AVM obliteration rate was 58.5% at 3 years and 78.0% at 5 years. The significant factors for higher complete obliteration rate were younger patient age and smaller maximum/minimum nidus diameter ratio. Two patients experienced hemorrhage caused by residual AVM rupture at 4 and 49 months. Twenty patients developed peri-nidal edema as an adverse radiation-induced reaction at median 13 months. One patient developed radiation-induced necrosis at 6.8 years. Neurological complication was observed in 12 patients and 6 patients remained with neurological dysfunction permanently. Larger nidus volume and location adjacent to an eloquent area significantly increased the risk of neurological complication. Pittsburgh radiosurgery-based AVM grading scale was significantly correlated with the outcome of neurological symptoms after GKS. GKS achieved acceptable and complete obliteration rate for posterior fossa AVM with relatively low risk of morbidity on neuroimaging and neurological symptoms for the long-term period after treatment. We recommend conformable and selective treatment planning to achieve both obliteration of the AVM nidus and preservation of neurological function. (author)

Toxicity of Gamma Knife Radiosurgery in the Treatment of Intracranial Tumors in Patients With Collagen Vascular Diseases or Multiple Sclerosis

International Nuclear Information System (INIS)

Lowell, Dot; Tatter, Stephen B.; Bourland, J. Daniel; Guzman, Allan F. de; Ekstrand, Kenneth E.; Ellis, Thomas L.; Lovato, James F.; McMullen, Kevin P.; Munley, Michael T.; Shaw, Edward G.; Urbanic, James J.; Chan, Michael D.

2011-01-01

Purpose: To assess toxicity in patients with either a collagen vascular disease (CVD) or multiple sclerosis (MS) treated with intracranial radiosurgery. Methods and Materials: Between January 2004 and April 2009, 6 patients with MS and 14 patients with a CVD were treated with Gamma Knife radiosurgery (GKRS) for intracranial tumors. Treated lesions included 15 total brain metastases in 7 patients, 11 benign brain tumors, 1 low grade glioma, and 1 cavernous malformation. Toxicities were graded by the Radiation Therapy Oncology Group Acute/Late Radiation Morbidity Scoring Criteria. “Rare toxicities” were characterized as those reported in the scientific literature at an incidence of 3 (range, 0.14–7.8 cm 3 ). Of the 14 patients with CVD, none experienced a Grade 3 or 4 toxicity or a toxicity characterized as rare. Of the 6 patients with MS, 3 experienced rare toxicities, and two of these were Grade 3 toxicities. Rare complications included a patient experiencing both communicating hydrocephalus and facial nerve palsy, as well as 2 additional patients with motor cranial nerve palsy. High-grade toxicities included the patient with an acoustic neuroma requiring ventriculoperitoneal shunt placement for obstructive hydrocephalus, and 1 patient with a facial nerve schwannoma who experienced permanent facial nerve palsy. Interval between radiosurgery and high-grade toxicities ranged from 1 week to 4 months. Conclusions: Our series suggests that patients with MS who receive GKRS may be at increased risk of rare and high-grade treatment-related toxicity. Given the time course of toxicity, treatment-related edema or demyelination represent potential mechanisms.

Gamma Knife radiosurgery for hemangioma of the cavernous sinus.

Science.gov (United States)

Lee, Cheng-Chia; Sheehan, Jason P; Kano, Hideyuki; Akpinar, Berkcan; Martinez-Alvarez, Roberto; Martinez-Moreno, Nuria; Guo, Wan-Yuo; Lunsford, L Dade; Liu, Kang-Du

2017-05-01

OBJECTIVE Cavernous sinus hemangiomas (CSHs) are rare vascular tumors. A direct microsurgical approach usually results in massive hemorrhage and incomplete tumor resection. Although stereotactic radiosurgery (SRS) has emerged as a therapeutic alternative to microsurgery, outcome studies are few. Authors of the present study evaluated the role of SRS for CSH. METHODS An international multicenter study was conducted to review outcome data in 31 patients with CSH. Eleven patients had initial microsurgery before SRS, and the other 20 patients (64.5%) underwent Gamma Knife SRS as the primary management for their CSH. Median age at the time of radiosurgery was 47 years, and 77.4% of patients had cranial nerve dysfunction before SRS. Patients received a median tumor margin dose of 12.6 Gy (range 12-19 Gy) at a median isodose of 55%. RESULTS Tumor regression was confirmed by imaging in all 31 patients, and all patients had greater than 50% reduction in tumor volume at 6 months post-SRS. No patient had delayed tumor growth, new cranial neuropathy, visual function deterioration, adverse radiation effects, or hypopituitarism after SRS. Twenty-four patients had presented with cranial nerve disorders before SRS, and 6 (25%) of them had gradual improvement. Four (66.7%) of the 6 patients with orbital symptoms had symptomatic relief at the last follow-up. CONCLUSIONS Stereotactic radiosurgery was effective in reducing the volume of CSH and attaining long-term tumor control in all patients at a median of 40 months. The authors' experience suggests that SRS is a reasonable primary and adjuvant treatment modality for patients in whom a CSH is diagnosed.

Quality assurance for gamma knives

International Nuclear Information System (INIS)

Jones, E.D.; Banks, W.W.; Fischer, L.E.

1995-09-01

This report describes and summarizes the results of a quality assurance (QA) study of the Gamma Knife, a nuclear medical device used for the gamma irradiation of intracranial lesions. Focus was on the physical aspects of QA and did not address issues that are essentially medical, such as patient selection or prescription of dose. A risk-based QA assessment approach was used. Sample programs for quality control and assurance are included. The use of the Gamma Knife was found to conform to existing standards and guidelines concerning radiation safety and quality control of external beam therapies (shielding, safety reviews, radiation surveys, interlock systems, exposure monitoring, good medical physics practices, etc.) and to be compliant with NRC teletherapy regulations. There are, however, current practices for the Gamma Knife not covered by existing, formalized regulations, standards, or guidelines. These practices have been adopted by Gamma Knife users and continue to be developed with further experience. Some of these have appeared in publications or presentations and are slowly finding their way into recommendations of professional organizations

Quality assurance for gamma knives

Energy Technology Data Exchange (ETDEWEB)

Jones, E.D.; Banks, W.W.; Fischer, L.E. [Lawrence Livermore National Lab., CA (United States)

1995-09-01

This report describes and summarizes the results of a quality assurance (QA) study of the Gamma Knife, a nuclear medical device used for the gamma irradiation of intracranial lesions. Focus was on the physical aspects of QA and did not address issues that are essentially medical, such as patient selection or prescription of dose. A risk-based QA assessment approach was used. Sample programs for quality control and assurance are included. The use of the Gamma Knife was found to conform to existing standards and guidelines concerning radiation safety and quality control of external beam therapies (shielding, safety reviews, radiation surveys, interlock systems, exposure monitoring, good medical physics practices, etc.) and to be compliant with NRC teletherapy regulations. There are, however, current practices for the Gamma Knife not covered by existing, formalized regulations, standards, or guidelines. These practices have been adopted by Gamma Knife users and continue to be developed with further experience. Some of these have appeared in publications or presentations and are slowly finding their way into recommendations of professional organizations.

Stereotactic gamma radiosurgery of pineal and related tumors

International Nuclear Information System (INIS)

Kobayashi, Tatsuya; Mori, Yoshimasa; Yamada, Yasushi; Kida, Yoshihisa

2001-01-01

The role of gamma radiosurgery as an additional therapy after conventional treatments for pineal and related tumors was studied in 30 out of 33 cases with a mean follow-up of 23.3 months. Overall results showed that complete response (CR) was obtained in 8 cases (26.7%) and response rate was 73.3%. However, enlargement of the tumors was noted in 8 cases, of which 7 (23.3%) died of tumor progression (PG). Germinomas and pineocytomas showed higher response and control rates of 100%, and no tumor enlargement or death occurred after gamma knife treatment. In germinoma with STGC (syncytiotrophoblastic giant cell) which has been thought to have intermediate prognosis, two cases showed partial response (PR), but another died from progression of the disease. Malignant germ cell tumors and pineoblastomas showed unfavorable response and prognosis; the response and progression rates were 50%. However, complete response was obtained in 3 cases (25%) after gamma radiosurgery. Gamma knife was the initial treatment in three cases without pathological diagnosis in which one obtained CR and two showed partial response (PR). Stereotactic gamma radiosurgery is expected to be an effective and novel treatment for pineal and related tumors not only as an adjuvant, but also as an initial therapy. (author)

Measurement of Gamma Knife registered helmet factors using MOSFETs

International Nuclear Information System (INIS)

Kurjewicz, Laryssa; Berndt, Anita

2007-01-01

The relative dose rate for the different Gamma Knife registered helmets (4, 8, 14, and 18 mm) is characterized by their respective helmet factors. Since the plateau of the dose profile for the 4 mm helmet is at most 1 mm wide, detector choices are limited. Traditionally helmet factors have been measured using 1x1x1 mm 3 thermoluminescent dosimeters (TLDs). However, these are time-consuming, cumbersome measurements. This article investigates the use of metal-oxide-semiconductor field effect transistors (MOSFETs) (active area of 0.2x0.2 mm 2 ) as a more accurate and convenient dosimeter. Their suitability for these measurements was confirmed by basic characterization measurements. Helmet factors were measured using both MOSFETs and the established TLD approach. A custom MOSFET cassette was designed in analogy to the Elekta TLD cassette (Elekta Instruments AB) for use with the Elekta dosimetry sphere. Although both dosimeters provided values within 3% of the manufacturer's suggestion, MOSFETs provided superior accuracy and precision, in a fraction of the time required for the TLD measurements. Thus, MOSFETs proved to be a reasonable alternative to TLDs for performing helmet factor measurements

Situated cognition in clinical visualization: the role of transparency in GammaKnife neurosurgery planning.

Science.gov (United States)

Dinka, David; Nyce, James M; Timpka, Toomas

2009-06-01

The aim of this study was to investigate how the clinical use of visualization technology can be advanced by the application of a situated cognition perspective. The data were collected in the GammaKnife radiosurgery setting and analyzed using qualitative methods. Observations and in-depth interviews with neurosurgeons and physicists were performed at three clinics using the Leksell GammaKnife. The users' ability to perform cognitive tasks was found to be reduced each time visualizations incongruent with the particular user's perception of clinical reality were used. The main issue here was a lack of transparency, i.e. a black box problem where machine representations "stood between" users and the cognitive tasks they wanted to perform. For neurosurgeons, transparency meant their previous experience from traditional surgery could be applied, i.e. that they were not forced to perform additional cognitive work. From the view of the physicists, on the other hand, the concept of transparency was associated with mathematical precision and avoiding creating a cognitive distance between basic patient data and what is experienced as clinical reality. The physicists approached clinical visualization technology as though it was a laboratory apparatus--one that required continual adjustment and assessment in order to "capture" a quantitative clinical reality. Designers of visualization technology need to compare the cognitive interpretations generated by the new visualization systems to conceptions generated during "traditional" clinical work. This means that the viewpoint of different clinical user groups involved in a given clinical task would have to be taken into account as well. A way forward would be to acknowledge that visualization is a socio-cognitive function that has practice-based antecedents and consequences, and to reconsider what analytical and scientific challenges this presents us with.

SU-E-E-15: Design of a Water Calorimeter for Dual Use in An Integrated MRI-Linac and Gamma-Knife

Energy Technology Data Exchange (ETDEWEB)

Entezari, N [Ryerson University, Toronto, Ontario (Canada); Renaud, J [McGill University, Montreal, Quebec (Canada); Ly, D [Waterloo University, Waterloo, Ontario (Canada); Sarfehnia, A [Sunnybrook Hospital, Toronto, ON (Canada)

2015-06-15

Purpose: To design a water calorimeter for dual use in an integrated MRI-linac and Gamma-Knife. In calorimetry, dose to water is measured based on the assumption that energy absorbed in a sensitive volume is completely converted to temperature rise {sub (}ΔΤ{sub )} according to the specific heat capacity of the medium c: D=c*ΔT*k, where k is heat transfer correction factor and compensates for heat gain or loss at point of measurement due to conductive effects. Methods: A commercial finite element method software package was used to model four different water calorimeter designs. The long term (48 h) thermal stability of each design was accurately modeled, and the optimization of the final design was based on evaluation of the standard deviation of k for ten consecutive irradiation runs (lower standard deviation translates to greater thermal stability). Several insulator materials of varying thicknesses were investigated, and a sensitivity study of thermal stability to variations in ambient temperature fluctuations was undertaken. Specifically, we evaluated the effect of possible variations in coolant temperature circulating around the calorimeter tank in several scenarios (constant, slowly increasing, or fluctuating). Results: Due to MRI-compatibility requirements, the calorimeter is to be built entirely out of plastic. Among all insulation materials tested, solid state aerogel-based insulation resulted in least heat loss and thermal stability. The final design is cylindrical on top (to be used upright in MRI-linac) and semi-spherical at bottom (for use in GammaKnife). The range of k was found to be 1.002 ± 0.013 (k = 1), comparable with a k of 1.002 ± 0.014 for typical water calorimeters used in high energy beams. A long term stability of 0.36 µK/hr was evaluated. Conclusion: Optimization of a water calorimeter design for dual use in MRI-linac and Gamma-Knife has been completed and the device is currently in production. Supported by NSERC RGPIN 435608.

SU-E-E-15: Design of a Water Calorimeter for Dual Use in An Integrated MRI-Linac and Gamma-Knife

International Nuclear Information System (INIS)

Entezari, N; Renaud, J; Ly, D; Sarfehnia, A

2015-01-01

Purpose: To design a water calorimeter for dual use in an integrated MRI-linac and Gamma-Knife. In calorimetry, dose to water is measured based on the assumption that energy absorbed in a sensitive volume is completely converted to temperature rise ( ΔΤ ) according to the specific heat capacity of the medium c: D=c*ΔT*k, where k is heat transfer correction factor and compensates for heat gain or loss at point of measurement due to conductive effects. Methods: A commercial finite element method software package was used to model four different water calorimeter designs. The long term (48 h) thermal stability of each design was accurately modeled, and the optimization of the final design was based on evaluation of the standard deviation of k for ten consecutive irradiation runs (lower standard deviation translates to greater thermal stability). Several insulator materials of varying thicknesses were investigated, and a sensitivity study of thermal stability to variations in ambient temperature fluctuations was undertaken. Specifically, we evaluated the effect of possible variations in coolant temperature circulating around the calorimeter tank in several scenarios (constant, slowly increasing, or fluctuating). Results: Due to MRI-compatibility requirements, the calorimeter is to be built entirely out of plastic. Among all insulation materials tested, solid state aerogel-based insulation resulted in least heat loss and thermal stability. The final design is cylindrical on top (to be used upright in MRI-linac) and semi-spherical at bottom (for use in GammaKnife). The range of k was found to be 1.002 ± 0.013 (k = 1), comparable with a k of 1.002 ± 0.014 for typical water calorimeters used in high energy beams. A long term stability of 0.36 µK/hr was evaluated. Conclusion: Optimization of a water calorimeter design for dual use in MRI-linac and Gamma-Knife has been completed and the device is currently in production. Supported by NSERC RGPIN 435608

Effective usage of a clearance check to avoid a collision in Gamma Knife Perfexion radiosurgery with the Leksell skull frame

International Nuclear Information System (INIS)

Nakazawa, Hisato; Komori, Masataka; Tsugawa, Takahiko; Hagiwara, Masahiro; Hashizume, Chisa; Kobayashi, Tatsuya; Mori, Yoshimasa; Shibamoto, Yuta

2014-01-01

Skull frame attachment is one of the most significant issues with Gamma Knife radiosurgery. Because of the potential for suffering by patients, careful control of the frame position is required to avoid circumstances such as collision between the frame or the patient's head and the collimator helmet, and inaccessible target coordinates. This study sought to develop a simulation method to find the appropriate frame location on the patient's head by retrospective analysis of treatment plans for brain metastasis cases. To validate the accuracy of the collision warning, we compared the collision distance calculated using Leksell Gamma Plan (LGP) with actual measured distances. We then investigated isocenter coordinates in near-collision cases using data from 844 previously treated patients and created a clearance map by superimposing them on CT images for just the frame, post and stereotactic fiducial box. The differences in distance between the simulation in LGP and the measured values were <1.0 mm. In 177 patients, 213 lesions and 461 isocenters, there was a warning of one possible collision. The clearance map was helpful for simulating appropriate skull frame placement. The clearance simulation eliminates the psychological stress associated with potential collisions, and enables more comfortable treatment for the patient. (author)

Stereotactic radiosurgery with the gamma knife. Possibilities of dose distribution optimizations

International Nuclear Information System (INIS)

Stuecklschweiger, G.

1995-01-01

On April 1992, the first stereotactic radiosurgical procedure using the gamma knife was performed at the University Medical School Graz, Department of Neurosurgery. Accurate dose optimization is the foundation of a convenient and responsible utilization of this modality. But there are limits, because the final collimation is only achieved by 1 of the 4 special helm collimators. The possibilities of dose optimization and its influence on the dose distributions were investigated and partly compared with results of film densitometry measurements. In detail, the technique, which uses the same isocenter, but different sized collimators was studied. The influence of these optimization techniques on the resulting dose distributions and the dose gradient at the edge of the treatment planning volume was analyzed. Also the visions for an effective dose optimization are discussed. With 2 shots of different diameters, located at the same target coordinates and different weighting of time any collimator size between the 4 mm and 18 mm can be achieved. Because of that, a combination of more than 2 collimators is not meaningful. With the combined shots the dose fall gradient was less than that of either of the single shots involved in the combination. With the available physical and technical possibilities only a limited, very time consuming optimization is practicable. The quality control of isodose distributions requires optimizations in hard-and software, that enable CT- or MRT-based 3-dimensional visualization and dose volume analysis. (orig./MG) [de

Gamma Knife radiosurgery for intracranial meningiomas: Do we need to treat the dural tail? A single-center retrospective analysis and an overview of the literature.

Science.gov (United States)

Bulthuis, Vincent J; Hanssens, Patrick E J; Lie, Suan Te; van Overbeeke, Jacobus J

2014-01-01

The dural tail (DT) has been described as a common feature in meningiomas. There is a great variation of tumor invasion and extent of tumor cells in the DT. Therefore, the necessity to include the whole DT in Gamma Knife radiosurgery is not clear, since inclusion increases the target volume and therefore increases the risk of complications. In this analysis, we evaluated whether the complete tail should be included as part of the target in Gamma Knife radiosurgery for meningiomas. Between June 2002 and December 2010, Gamma Knife radiosurgery was performed in 160 patients with 203 meningiomas with a DT. In 105 tumors, the diagnosis was based on magnetic resonance imaging (MRI) characteristics, and in 98 tumors, the diagnosis was confirmed by histopathologic examination after surgery. The median volume of the tumors was 3.55 cc. All tumors were treated with Gamma Knife radiosurgery with a median prescribed dose of 13 Gy (range 11-15), resulting in a median marginal dose of 11 Gy (range 10-15). Only the part of the DT closely related to the tumor mass was included in the target. The median follow-up period was 41 months (range 12-123). In image-based meningiomas, the overall local control rate was 96.2% with 2- and 5-year control rates of 98.0% and 95.1%, respectively. In WHO grade I tumors, the overall local control rate was 85.9% with 2- and 5-year control rates of 94.5% and 88.0%, respectively. The overall local control rate in World Health Organization (WHO) grade II tumors was 70.6% with control rates of 83.4% and 64.4% after 2 and 5 years, respectively. The growth of all new tumors was found in the radiation target area. No tumor growth was observed in the part of the DT that had been excluded from the target volume. We found in this study that routinely excluding the DT from the target does not lead to out-of-field tumor progression. Given the possibility that the DT is infiltrated with tumor cells, regular follow-up is needed.

Gamma Knife radiosurgery for large vestibular schwannomas greater than 3 cm in diameter.

Science.gov (United States)

Huang, Cheng-Wei; Tu, Hsien-Tang; Chuang, Chun-Yi; Chang, Cheng-Siu; Chou, Hsi-Hsien; Lee, Ming-Tsung; Huang, Chuan-Fu

2018-05-01

OBJECTIVE Stereotactic radiosurgery (SRS) is an important alternative management option for patients with small- and medium-sized vestibular schwannomas (VSs). Its use in the treatment of large tumors, however, is still being debated. The authors reviewed their recent experience to assess the potential role of SRS in larger-sized VSs. METHODS Between 2000 and 2014, 35 patients with large VSs, defined as having both a single dimension > 3 cm and a volume > 10 cm 3 , underwent Gamma Knife radiosurgery (GKRS). Nine patients (25.7%) had previously undergone resection. The median total volume covered in this group of patients was 14.8 cm 3 (range 10.3-24.5 cm 3 ). The median tumor margin dose was 11 Gy (range 10-12 Gy). RESULTS The median follow-up duration was 48 months (range 6-156 months). All 35 patients had regular MRI follow-up examinations. Twenty tumors (57.1%) had a volume reduction of greater than 50%, 5 (14.3%) had a volume reduction of 15%-50%, 5 (14.3%) were stable in size (volume change 3 cm and a volume > 10 cm 3 and tolerable mass effect can be managed satisfactorily with GKRS. Tumor volume ≥ 15 cm 3 is a significant factor predicting poor tumor control following GKRS.

A case of chemotherapy-resistant intestinal-type sinonasal adenocarcinoma treated by gamma knife radiosurgery

Directory of Open Access Journals (Sweden)

Andres M. Alvarez-Pinzon, M.D., Ph.D.

2017-12-01

Full Text Available Intestinal type sinonasal adenocarcinomas are a rare malignancy of the nasal cavity and paranasal sinuses ascending in the nasal cavity are particularly unusual. We report an infrequent case of an Intestinal sinonasal adenocarcinoma from the left lateral nasal wall. A 60-year-old Hispanic male complained of complete progressive nasal obstruction and epistaxis for 8 months. A nasal endoscopic exam displayed a prominent enlargement, which remained in connection with the anterior part of left inferior turbinate. Computed tomography revealed a medium-defined, soft tissue dense lesion in the left anterior nasal cavity. Mass biopsy histology confirmed a low grade differentiate Intestinal type sinonasal adenocarcinomas. The patient underwent 8 cycles of chemotherapy including paclitaxel, platinol and fluorouracil. According to the medical records, the patient responded well to the chemotherapy treatment until about six cycles. When a follow up CT scan showed tumor growth, the patient was placed on Doxorubicin but developed toxicity. The main treatment modality is surgical resection with histological clear margins but concerning the low differentiation, low response of chemotherapy, and surgical risk we offered an option with gamma knife radiosurgery. In our case, the patient demonstrated satisfactory relief of symptoms and reported the ability to breathe through the nose. 80% of tumor resolution was observed in 1 month following the CT scan.

Gamma Knife Radiosurgery for Treatment of Cerebral Metastases From Non–Small-Cell Lung Cancer

International Nuclear Information System (INIS)

Motta, Micaela; Vecchio, Antonella del; Attuati, Luca; Picozzi, Piero; Perna, Lucia; Franzin, Alberto; Bolognesi, Angelo; Cozzarini, Cesare; Calandrino, Riccardo; Mortini, Pietro; Muzio, Nadia di

2011-01-01

Purpose: To evaluate clinical and physico-dosimetric variables affecting clinical outcome of patients treated with Gamma Knife radiosurgery (GKRS) for brain metastases from non–small cell lung cancer (NSCLC). Methods and Materials: Between 2001 and 2006, 373 patients (298 men and 75 women, median age 65 years) with brain metastases from NSCLC underwent GKRS. All of them had KPS ≥ 60%, eight or fewer brain metastases, confirmed histopathological diagnosis and recent work-up ( 3 . Median marginal dose was 22.5 Gy at 50% isodose.; median 10 Gy and 12 Gy isodose volumes were 30.8 cm 3 and 15.8 cm 3 , respectively. Follow-up with MRI was performed every 3 months. Overall survival data were collected from internal database, telephone interviews, and identifying registries. Results: Mean follow-up after GKRS was 51 months (range, 6 to 96 months); mean overall survival was 14.2 months. Of 373 patients, 29 were alive at time of writing, 104 had died of cerebral progression, and 176 had died of systemic progression. In 64 cases it was not possible to ascertain the cause. Univariate and multivariate analysis were adjusted for the following: RPA class, surgery, WBRT, age, gender, number of lesions, median tumor volume, median peripheral dose, and 10 Gy and 12 Gy volumes. Identified RPA class and overall tumor volume >5 cc were the only two covariates independently predictive of overall survival in patients who died of cerebral progression. Conclusions: Global volume of brain disease should be the main parameter to consider for performing GKRS, which is a first-line therapy for patient in good general condition and controlled systemic disease.

SU-E-T-476: Quality Assurance for Gamma Knife Perfexion Using the Exradin W1 Plastic Scintillation Detector

Energy Technology Data Exchange (ETDEWEB)

Pino, R [Houston Methodist Hospital (United States); Therriault-Proulx, F; Yang, J; Beddar, S [University of Texas MD Anderson Cancer Center, Houston, TX (United States)

2014-06-01

Purpose: To perform dose profile and output factor measurements for the Exradin W1 plastic scintillation detector (PSD) for the Gamma Knife Perfexion (GKP) collimators in a Lucy phantom and to compare these values to an Exradin A16 ion chamber, EBT3 radiochromic film and treatment planning system (TPS) data. Methods: We used the Exradin W1 PSD which has a small volume, near-water equivalent sensitive element. It has also been shown to be energy independent. This new detector is manufactured and distributed by Standard Imaging, Inc. Measurements were performed for all three collimators (4 mm, 8 mm and 16 mm) for the GKP. The Lucy phantom with the PSD inserted was moved in small steps to acquire profiles in all three directions. EBT3 film was inserted in the Lucy phantom and exposed to a single shot for each collimator. Relative output factors were measured using the three detectors while profiles acquired with the PSD were compared to the ones measured with EBT3 radiochromic film. Results: Measured output factors relative to the largest collimator are as followsCollimator PS EBT3 A1616mm 1.000 1.000 1.0008mm 0.892 0.881 0.8834mm 0.795 0.793 0.727 The nominal (vendor) OFs for GKP are 1.000, 0.900, and 0.814, for collimators 16 mm, 8 mm and 4 mm, respectively. There is excellent agreement between all profiles measured with the PSD and EBT3 as well as with the TPS data provided by the vendor. Conclusion: Output factors measured with the W1 were consistent with the ones measured with EBT3 and A16 ion chamber. Measured profiles are in excellent agreement. The W1 detector seems well suited for beam QA for Gamma Knife due to its dosimetric characteristics. Sam Beddar would like to disclose a NIH/NCI SBIR Phase II grant (2R44CA153824-02A1) with Standard Imaging, Title: “Water-Equivalent Plastic Scintillation Detectors for Small Field Radiotherapy”.

Analysis of dosimetry of a Gamma Knife Perfexion using polystyrene and solid water phantoms for small volume ionization chambers; Analise da dosimetria de um Gamma Knife Perfexion utilizando phantoms de poliestireno e de agua solida para camaras de ionizacao de volume pequeno

Energy Technology Data Exchange (ETDEWEB)

Costa, N.A.; Potiens, M.P.A., E-mail: nathaliaac@ymail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Saraiva, C.W.C. [Hospital do Coracao (HCor), Sao Paulo, SP (Brazil); Benmakhlouf, H. [Stockholm University, Karolinska Hospital (Sweden)

2016-07-01

The Gamma Knife Perfexion (GKP) is a radiosurgery equipment that has been developed by Elekta. Its dose-rate calibration is performed using phantoms developed by Elekta and a small volume ionization chamber. The purpose of this study was to evaluate the collected charge values obtained in its dosimetry using two different phantoms, polystyrene and solid water and the ion chambers PTW Semiflex, volume 0,125 cm{sup 3}, model 31010 and PTW Pinpoint, volume 0,016 cm{sup 3}, model 31016. (author)

Determination of Absorbed Dose to Water for Leksell Gamma Knife Unit

International Nuclear Information System (INIS)

Hrsak, H.

2013-01-01

Because of geometry of photon beams in Leksell Gamma Knife Unit (LGK), there are several technical problems in applying standard protocols for determination of absorbed dose to water (Dw). Currently, Dw in LGK unit, measured at the center of spherical plastic phantom, is used for dose calculation in LGK radiosurgery. Treatment planning software (LGP TPS) accepts this value as a measurement in water and since plastic phantom has higher electron density than water, this leads to systematic errors in dose calculation. To reduce these errors, a photon attenuation correction (PAC) method was applied. For that purpose, measurements of absorbed dose in a center of three different plastic phantoms with 16 cm diameter (ABS - acrylonitrile butadiene styrene, PMMA - polymethyl metacrylate, PMMA + teflon - polytetrafluoroethylene 5 mm shell) were made with ionization chamber (Semiflex, PTW Freiburg). For measured dose values, PAC to water was applied based on electron density (ED) and equivalent water depths (EWD) of the plastic phantoms. The relation between CT number and ED was determined by measuring CT number of standard CT to ED phantom (CIRS Model 062 Phantom). Absorbed dose in plastic phantoms was 2.5 % lower than calculated dose in water for ABS phantom and more than 5.5 % lower for PMMA and PMMA+teflon phantom. Calculated dose in water showed more consistent values for all three phantoms (max. difference 2.6 %). EWD for human cranial bones and brain has value close to the EWD of ABS phantom, which makes this phantom most suitable for dose measurements in clinical application. In LGK radiosurgery determination of errors related to the difference of phantom materials should not be neglected and measured dose should be corrected before usage for patient treatment dose calculation.(author)

[Randomized controlled trials of needle knife therapy combined with rotation traction manipulation for the treatment of cervical spondylotic radiculopathy].

Science.gov (United States)

Zhou, Zhong-Liang; Su, Guo-Hong; Zheng, Bao-Zhu; Zuo, Yu-Zhu; Wei, Fu-Liang

2016-09-25

To compare the therapeutic effects between needle knife therapy combined with rotation traction manipulation and rotation traction manipulation for the treatment of cervical spondylotic radiculopathy. From November 2013 to June 2015, 80 patients with cervical spondylotic radiculopathy meeting the inclusion criteria were divided into two groups randomly:the control group in which 39 patients were treated with rotation traction manipulation, and the treatment group in which 41 patients were treated with needle knife combined with rotation traction manipulation. The patients in the control group were treated once dayly for 2 weeks, which was 1 course. The patients in the treatment group were treated with needle knife firstly once a week for 2 weeks, which was 1 course;then were treated with the same methods as the patients in the control group. The symptoms, signs score and the therapeutic effects of the two groups before and after treatment were observed. After treatment, symptoms and signs scores declined in both groups( P knife combined with rotation traction manipulation is an effective method for the treatment of cervical spondylotic radiculopathy, which is better than using manipulation method simply. Needle knife therapy has follow advantages:improving local blood circulation, reducing local content of pain substance, increasing production of substances resisting pain, opening channels and collaterals, and make body reaching new static and dynamic balance on the new foundation.

Measurement of prompt gamma profiles in inhomogeneous targets with a knife-edge slit camera during proton irradiation

International Nuclear Information System (INIS)

Priegnitz, M; Helmbrecht, S; Fiedler, F; Janssens, G; Smeets, J; Vander Stappen, F; Perali, I; Sterpin, E

2015-01-01

Proton and ion beam therapies become increasingly relevant in radiation therapy. To fully exploit the potential of this irradiation technique and to achieve maximum target volume conformality, the verification of particle ranges is highly desirable. Many research activities focus on the measurement of the spatial distributions of prompt gamma rays emitted during irradiation. A passively collimating knife-edge slit camera is a promising option to perform such measurements. In former publications, the feasibility of accurate detection of proton range shifts in homogeneous targets could be shown with such a camera. We present slit camera measurements of prompt gamma depth profiles in inhomogeneous targets. From real treatment plans and their underlying CTs, representative beam paths are selected and assembled as one-dimensional inhomogeneous targets built from tissue equivalent materials. These phantoms have been irradiated with monoenergetic proton pencil beams. The accuracy of range deviation estimation as well as the detectability of range shifts is investigated in different scenarios. In most cases, range deviations can be detected within less than 2 mm. In close vicinity to low-density regions, range detection is challenging. In particular, a minimum beam penetration depth of 7 mm beyond a cavity is required for reliable detection of a cavity filling with the present setup. Dedicated data post-processing methods may be capable of overcoming this limitation. (paper)

Toxicity of Gamma Knife Radiosurgery in the Treatment of Intracranial Tumors in Patients With Collagen Vascular Diseases or Multiple Sclerosis

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Lowell, Dot [Department of Radiation Oncology, School of Medicine, Wake Forest University, Winston-Salem, NC (United States); Tatter, Stephen B. [Department of Neurosurgery, School of Medicine, Wake Forest University, Winston-Salem, NC (United States); Bourland, J. Daniel; Guzman, Allan F. de; Ekstrand, Kenneth E. [Department of Radiation Oncology, School of Medicine, Wake Forest University, Winston-Salem, NC (United States); Ellis, Thomas L. [Department of Neurosurgery, School of Medicine, Wake Forest University, Winston-Salem, NC (United States); Lovato, James F. [Division of Public Health Sciences, School of Medicine, Wake Forest University, Winston-Salem, NC (United States); McMullen, Kevin P.; Munley, Michael T.; Shaw, Edward G.; Urbanic, James J. [Department of Radiation Oncology, School of Medicine, Wake Forest University, Winston-Salem, NC (United States); Chan, Michael D., E-mail: mchan@wfubmc.edu [Department of Radiation Oncology, School of Medicine, Wake Forest University, Winston-Salem, NC (United States)

2011-11-15

Purpose: To assess toxicity in patients with either a collagen vascular disease (CVD) or multiple sclerosis (MS) treated with intracranial radiosurgery. Methods and Materials: Between January 2004 and April 2009, 6 patients with MS and 14 patients with a CVD were treated with Gamma Knife radiosurgery (GKRS) for intracranial tumors. Treated lesions included 15 total brain metastases in 7 patients, 11 benign brain tumors, 1 low grade glioma, and 1 cavernous malformation. Toxicities were graded by the Radiation Therapy Oncology Group Acute/Late Radiation Morbidity Scoring Criteria. 'Rare toxicities' were characterized as those reported in the scientific literature at an incidence of <5%. Results: Median follow-up time was 16 months. Median dose to the tumor margin was 13.0 Gy (range, 12-21 Gy). Median size of tumor was 5.0 cm{sup 3} (range, 0.14-7.8 cm{sup 3}). Of the 14 patients with CVD, none experienced a Grade 3 or 4 toxicity or a toxicity characterized as rare. Of the 6 patients with MS, 3 experienced rare toxicities, and two of these were Grade 3 toxicities. Rare complications included a patient experiencing both communicating hydrocephalus and facial nerve palsy, as well as 2 additional patients with motor cranial nerve palsy. High-grade toxicities included the patient with an acoustic neuroma requiring ventriculoperitoneal shunt placement for obstructive hydrocephalus, and 1 patient with a facial nerve schwannoma who experienced permanent facial nerve palsy. Interval between radiosurgery and high-grade toxicities ranged from 1 week to 4 months. Conclusions: Our series suggests that patients with MS who receive GKRS may be at increased risk of rare and high-grade treatment-related toxicity. Given the time course of toxicity, treatment-related edema or demyelination represent potential mechanisms.

Investigation of intracranial peripheral dose arising from the treatment of large lesions with Leksell GammaKnife Perfexion.

Science.gov (United States)

Ruschin, Mark; Nordström, Håkan; Kjäll, Per; Cho, Young-Bin; Jaffray, David

2009-06-01

This investigation involves quantifying the extent of intracranial peripheral dose arising from simulated targets situated in the skull-base or upper-spine region using the Leksell GammaKnife Perfexion treatment unit. For each of three spherical target volumes--denoted as Vs (4 cm3), VM (18 cm3), and VL (60 cm3)--three treatment plans were manually generated, one for each of the three collimator sizes--4, 8, and 16 mm. Each of the plans was delivered to a spherical dosimetry phantom with an insert containing EBT Gafchromic film. The total dose at 70 mm from the targets' edges, %D(70 mm), was measured as a function of elevation angle and expressed as a percentage of the prescription dose. The film insert was placed centered in the median sagittal plane (Leksell X = 100) and %D(70 mm) was measured for the angular range from 0 degree (superior/along Z axis) to 90 degrees (anterior/along Y axis). For a given collimator i, the irradiation time ti to treat a spherical target of volume V using the 50% isodose line was observed to follow a power-law relationship of the form ti = Ai(V/ Vi)n where Ai was the maximum dose divided by collimator dose rate and Vi was the volume encompassed by the 50% isodose line for a single shot. The mean value of n was 0.61 (range: 0.61-0.62). Along the superior (Z) direction (angle=0 degree) and up to angles of around 30 degrees, the %D(70 mm) was always highest for the 4 mm plans, followed by the 8 mm, followed by the 16 mm. In this angular range, the maximum measured %D(70 mm) was 1.7% of the prescription dose. The intracranial peripheral dose along the superior direction (combined scatter and leakage dose) resulting from irradiation of upper-spine or base-of-skull lesions is measured to be less than 2% of the prescription dose, even for very large (60 cm3) targets. The results of this study indicate that, for a given target volume, treatment plans consisting of only 4 mm shots yield larger peripheral dose in the superior direction than 8

Pathologic effects of gamma-knife radiosurgery on arteriovenous malformations

International Nuclear Information System (INIS)

Schneider, B.F.; Eberhard, D.A.; Steiner, L.

1995-01-01

Objective: Stereotactic radiosurgery is an effective method for treating many arteriovenous malformations (AVM). Hemodynamic changes and varying degrees of obliteration of an AVM nidus following radiosurgery have been described with angiography, but there have been no detailed reports describing histopathologic changes in AVM after radiation. The purpose of this study was to examine AVM at various times after gamma-knife radiosurgery in order to determine the mechanism of vessel occlusion after this procedure. Methods: Nine AVM specimens were obtained at autopsy or after surgical excision of residual nidus at times ranging from 10 months to more than 5 years after gamma knife radiosurgery. Formalin fixed, paraffin-embedded sections were examined using routine histopathologic stains: hematoxylin and eosin (H and E), Mallory's phosphotungstic acid-hematoxylin (PTAH), Elastic-van Gieson (EVG), and Hematoxylin-van Gieson (HVG). Additionally, immunohistochemical techniques were used to detect: smooth muscle actin (SMA), Factor VIII, and Type IV collagen. Results: Blood vessels within the AVM show progressive occlusion which correlated with the time interval after radiosurgery. The earliest changes after radiation appear to be damage to and loss of endothelial cells. At this early stage of vascular damage fibrin thrombi are sometimes apparent in the lumen of vessels. With time after radiation there is progressive thickening of the intimal layer, due to proliferation of smooth muscle cells. It is clearly demonstrated, immunohistochemically, that this accumulation of cells within the intimal layer reacts positively for smooth muscle actin, and negatively for Factor VIII (an endothelial cell marker). Using immunohistochemistry it is, also, apparent that these smooth muscle cells are surrounded by an extracellular matrix of Type I collagen, which increases in amount and density over time. Ultimately, vessels are completely occluded by an acellular, amorphous hyalin

Magnetic resonance imaging characteristics and the prediction of outcome of vestibular schwannomas following Gamma Knife radiosurgery.

Science.gov (United States)

Wu, Chih-Chun; Guo, Wan-Yuo; Chung, Wen-Yuh; Wu, Hisu-Mei; Lin, Chung-Jung; Lee, Cheng-Chia; Liu, Kang-Du; Yang, Huai-Che

2017-12-01

OBJECTIVE Gamma Knife surgery (GKS) is a promising treatment modality for patients with vestibular schwannomas (VSs), but a small percentage of patients have persistent postradiosurgical tumor growth. The aim of this study was to determine the clinical and quantitative MRI features of VS as predictors of long-term tumor control after GKS. METHODS The authors performed a retrospective study of all patients with VS treated with GKS using the Leksell Gamma Knife Unit between 2005 and 2013 at their institution. A total of 187 patients who had a minimum of 24 months of clinical and radiological assessment after radiosurgery were included in this study. Those who underwent a craniotomy with tumor removal before and after GKS were excluded. Study patients comprised 85 (45.5%) males and 102 (54.5%) females, with a median age of 52.2 years (range 20.4-82.3 years). Tumor volumes, enhancing patterns, and apparent diffusion coefficient (ADC) values were measured by region of interest (ROI) analysis of the whole tumor by serial MRI before and after GKS. RESULTS The median follow-up period was 60.8 months (range 24-128.9 months), and the median treated tumor volume was 3.54 cm 3 (0.1-16.2 cm 3 ). At last follow-up, imaging studies indicated that 150 tumors (80.2%) showed decreased tumor volume, 20 (10.7%) had stabilized, and 17 (9.1%) continued to grow following radiosurgery. The postradiosurgical outcome was not significantly correlated with pretreatment volumes or postradiosurgical enhancing patterns. Tumors that showed regression within the initial 12 months following radiosurgery were more likely to have a larger volume reduction ratio at last follow-up than those that did not (volume reduction ratio 55% vs 23.6%, respectively; p < 0.001). Compared with solid VSs, cystic VSs were more likely to regress or stabilize in the initial postradiosurgical 6-12-month period and during extended follow-up. Cystic VSs exhibited a greater volume reduction ratio at last follow-up (cystic

Predictors of quality of life and survival following Gamma Knife surgery for lung cancer brain metastases: a prospective study.

Science.gov (United States)

Bragstad, Sidsel; Flatebø, Marianne; Natvig, Gerd Karin; Eide, Geir Egil; Skeie, Geir Olve; Behbahani, Maziar; Pedersen, Paal-Henning; Enger, Per Øyvind; Skeie, Bente Sandvei

2017-08-18

OBJECTIVE Lung cancer (LC) patients who develop brain metastases (BMs) have a poor prognosis. Estimations of survival and risk of treatment-related deterioration in quality of life (QOL) are important when deciding on treatment. Although we know of several prognostic factors for LC patients with BMs, the role of QOL has not been established. Authors of this study set out to evaluate changes in QOL following Gamma Knife surgery (GKS) for BMs in LC patients and QOL as a prognostic factor for survival. METHODS Forty-four of 48 consecutive LC patients with BMs underwent GKS in the period from May 2010 to September 2011, and their QOL was prospectively assessed before and 1, 3, 6, 9, and 12 months after GKS by using the Functional Assessment of Cancer Therapy-Brain (FACT-BR) questionnaire. A mixed linear regression model was used to identify potential predictive factors for QOL and to assess the effect of GKS and the disease course on QOL at follow-up. RESULTS Mean QOL as measured by the brain cancer subscale (BRCS) of the FACT-BR remained stable from baseline (score 53.0) up to 12 months post-GKS (57.1; p = 0.624). The BRCS score improved for 32 patients (72.3%) with a total BM volume ≤ 5 cm 3 . Mean improvement in these patients was 0.45 points each month of follow-up, compared to a decline of 0.50 points each month despite GKS treatment in patients with BM volumes > 5 cm 3 (p = 0.04). Asymptomatic BMs (p = 0.01), a lower recursive partitioning analysis (RPA) classification (p = 0.04), and a higher Karnofsky Performance Scale (KPS) score (p Knife surgery is a safe and effective therapeutic modality that improves QOL for LC patients with a BM volume ≤ 5 cm 3 at treatment. Careful follow-up and salvage therapy on demand seem to prevent worsening of QOL due to relapse of BMs.

Gamma Knife radiosurgery for intracranial meningiomas : Do we need to treat the dural tail? A single-center retrospective analysis and an overview of the literature

NARCIS (Netherlands)

Bulthuis, Vincent J; Hanssens, Patrick E J; Lie, Suan Te; van Overbeeke, Jacobus J

2014-01-01

BACKGROUND: The dural tail (DT) has been described as a common feature in meningiomas. There is a great variation of tumor invasion and extent of tumor cells in the DT. Therefore, the necessity to include the whole DT in Gamma Knife radiosurgery is not clear, since inclusion increases the target

Long-term follow-up studies of Gamma Knife surgery for patients with neurofibromatosis Type 2.

Science.gov (United States)

Sun, Shibin; Liu, Ali

2014-12-01

The aim of this study was to evaluate long-term clinical outcomes after Gamma Knife surgery (GKS) for patients with neurofibromatosis Type 2 (NF2) and the role of GKS in the management of NF2. From December 1994 through December 2008, a total of 46 patients (21 male, 25 female) with NF2 underwent GKS and follow-up evaluation for at least 5 years at the Gamma Knife Center of the Beijing Neurosurgical Institute. GKS was performed using the Leksell Gamma Knife Models B and C. The mean age of the patients was 30 years (range 13-59 years). A family history of NF2 was found for 9 (20%) patients. The NF2 phenotype was thought to be Wishart for 20 (44%) and Feiling-Gardner for 26 (56%) patients. Among these 46 patients, GKS was performed to treat 195 tumors (73 vestibular schwannomas and 122 other tumors including other schwannomas and meningiomas). For vestibular schwannomas, the mean volume was 5.1 cm(3) (median 3.6 cm(3), range 0.3-27.3 cm(3)), the mean margin dose was 12.9 Gy (range 10-14 Gy), and the mean maximum dose was 27.3 Gy (range 16.2-40 Gy). For other tumors, the mean volume was 1.7 cm(3) (range 0.3-5.5 cm(3)), the mean margin dose was 13.3 Gy (range 11-14 Gy), and the mean maximum dose was 26.0 Gy (range 18.0-30.4 Gy). The median duration of follow-up was 109 months (range 8-195 months). For the 73 vestibular schwannomas that underwent GKS, the latest follow-up MR images demonstrated regression of 30 (41%) tumors, stable size for 31 (43%) tumors, and enlargement of 12 (16%) tumors. The total rate of tumor control for bilateral vestibular schwannomas in patients with NF2 was 84%. Of the 122 other types of tumors that underwent GKS, 103 (85%) showed no tumor enlargement. The rate of serviceable hearing preservation after GKS was 31.9% (15/47). The actuarial rates for hearing preservation at 3 years, 5 years, 10 years, and 15 years were 98%, 93%, 44%, and 17%, respectively. Of the 46 patients, 22 (48%) became completely bilaterally deaf, 17 (37%) retained

Higher dose rate Gamma Knife radiosurgery may provide earlier and longer-lasting pain relief for patients with trigeminal neuralgia.

Science.gov (United States)

Lee, John Y K; Sandhu, Sukhmeet; Miller, Denise; Solberg, Timothy; Dorsey, Jay F; Alonso-Basanta, Michelle

2015-10-01

Gamma Knife radiosurgery (GKRS) utilizes cobalt-60 as its radiation source, and thus dose rate varies as the fixed source decays over its half-life of approximately 5.26 years. This natural decay results in increasing treatment times when delivering the same cumulative dose. It is also possible, however, that the biological effective dose may change based on this dose rate even if the total dose is kept constant. Because patients are generally treated in a uniform manner, radiosurgery for trigeminal neuralgia (TN) represents a clinical model whereby biological efficacy can be tested. The authors hypothesized that higher dose rates would result in earlier and more complete pain relief but only if measured with a sensitive pain assessment tool. One hundred thirty-three patients were treated with the Gamma Knife Model 4C unit at a single center by a single neurosurgeon during a single cobalt life cycle from January 2006 to May 2012. All patients were treated with 80 Gy with a single 4-mm isocenter without blocking. Using an output factor of 0.87, dose rates ranged from 1.28 to 2.95 Gy/min. The Brief Pain Inventory (BPI)-Facial was administered before the procedure and at the first follow-up office visit 1 month from the procedure (mean 1.3 months). Phone calls were made to evaluate patients after their procedures as part of a retrospective study. Univariate and multivariate linear regression was performed on several independent variables, including sex, age in deciles, diagnosis, follow-up duration, prior surgery, and dose rate. In the short-term analysis (mean 1.3 months), patients' self-reported pain intensity at its worst was significantly correlated with dose rate on multivariate analysis (p = 0.028). Similarly, patients' self-reported interference with activities of daily living was closely correlated with dose rate on multivariate analysis (p = 0.067). A 1 Gy/min decrease in dose rate resulted in a 17% decrease in pain intensity at its worst and a 22% decrease

A new strategy of CyberKnife treatment system based radiosurgery followed by early use of adjuvant bevacizumab treatment for brain metastasis with extensive cerebral edema.

Science.gov (United States)

Wang, Yang; Wang, Enmin; Pan, Li; Dai, Jiazhong; Zhang, Nan; Wang, Xin; Liu, Xiaoxia; Mei, Guanghai; Sheng, Xiaofang

2014-09-01

Bevacizumab blocks the effects of vascular endothelial growth factor in leakage-prone capillaries and has been suggested as a new treatment for cerebral radiation edema and necrosis. CyberKnife is a new, frameless stereotactic radiosurgery system. This work investigated the safety and efficacy of CyberKnife followed by early bevacizumab treatment for brain metastasis with extensive cerebral edema. The eligibility criteria of the patients selected for radiosurgery followed by early use of adjuvant bevacizumab treatment were: (1) brain tumors from metastasis with one solitary brain lesion and symptomatic extensive cerebral edema; (2) >18 years of age; (3) the patient refused surgery due to the physical conditions and the risk of surgery; (4) no contraindications for bevacizumab. (5) bevacizumab was applied for a minimum of 2 injections and a maximum of 6 injections with a 2-week interval between treatments, beginning within 2 weeks of the CyberKnife therapy; (6) Karnofsky performance status (KPS) ≥30. Tumor size and edema were monitored by magnetic resonance imaging (MRI). Dexamethasone dosage, KPS, adverse event occurrence and associated clinical outcomes were also recorded. Eight patients were accrued for this new treatment. Radiation dose ranged from 20 to 33 Gy in one to five sessions, prescribed to the 61-71 % isodose line. Bevacizumab therapy was administered 3-10 days after completion of CyberKnife treatment for a minimum of two cycles (5 mg/kg, at 2-week intervals). MRI revealed average reductions of 55.8 % (post-gadolinium) and 63.4 % (T2/FLAIR). Seven patients showed significant clinical neurological improvements. Dexamethasone was reduced in all patients, with five successfully discontinuing dexamethasone treatment 4 weeks after bevacizumab initiation. Hypertension, a bevacizumab-related adverse event, occurred in one patient. After 3-8 months, all patients studied were alive and primary brain metastases were under control, 2 developed new brain

Independent Monte-Carlo dose calculation for MLC based CyberKnife radiotherapy

Science.gov (United States)

Mackeprang, P.-H.; Vuong, D.; Volken, W.; Henzen, D.; Schmidhalter, D.; Malthaner, M.; Mueller, S.; Frei, D.; Stampanoni, M. F. M.; Dal Pra, A.; Aebersold, D. M.; Fix, M. K.; Manser, P.

2018-01-01

This work aims to develop, implement and validate a Monte Carlo (MC)-based independent dose calculation (IDC) framework to perform patient-specific quality assurance (QA) for multi-leaf collimator (MLC)-based CyberKnife® (Accuray Inc., Sunnyvale, CA) treatment plans. The IDC framework uses an XML-format treatment plan as exported from the treatment planning system (TPS) and DICOM format patient CT data, an MC beam model using phase spaces, CyberKnife MLC beam modifier transport using the EGS++ class library, a beam sampling and coordinate transformation engine and dose scoring using DOSXYZnrc. The framework is validated against dose profiles and depth dose curves of single beams with varying field sizes in a water tank in units of cGy/Monitor Unit and against a 2D dose distribution of a full prostate treatment plan measured with Gafchromic EBT3 (Ashland Advanced Materials, Bridgewater, NJ) film in a homogeneous water-equivalent slab phantom. The film measurement is compared to IDC results by gamma analysis using 2% (global)/2 mm criteria. Further, the dose distribution of the clinical treatment plan in the patient CT is compared to TPS calculation by gamma analysis using the same criteria. Dose profiles from IDC calculation in a homogeneous water phantom agree within 2.3% of the global max dose or 1 mm distance to agreement to measurements for all except the smallest field size. Comparing the film measurement to calculated dose, 99.9% of all voxels pass gamma analysis, comparing dose calculated by the IDC framework to TPS calculated dose for the clinical prostate plan shows 99.0% passing rate. IDC calculated dose is found to be up to 5.6% lower than dose calculated by the TPS in this case near metal fiducial markers. An MC-based modular IDC framework was successfully developed, implemented and validated against measurements and is now available to perform patient-specific QA by IDC.

Application of Electrocautery Needle Knife Combined with Balloon Dilatation versus Balloon Dilatation in the Treatment of Tracheal Fibrotic Scar Stenosis.

Science.gov (United States)

Bo, Liyan; Li, Congcong; Chen, Min; Mu, Deguang; Jin, Faguang

Electrocautery needle knives can largely reduce scar and granulation tissue hyperplasia and play an important role in treating patients with benign stricture. The aim of this retrospective study was to evaluate the efficacy and safety of electrocautery needle knife combined with balloon dilatation versus balloon dilatation alone in the treatment of tracheal stenosis caused by tracheal intubation or tracheotomy. We retrospectively analysed the clinical data of 43 patients with tracheal stenosis caused by tracheotomy or tracheal intubation in our department from January 2013 to January 2016. Among these 43 patients, 23 had simple web-like stenosis and 20 had complex steno sis. All patients were treated under general anaesthesia, and the treatment methods were (1) balloon dilatation alone, (2) needle knife excision of fibrotic tissue combined with balloon dilatation, and (3) needle knife radial incision of fibrotic tissue combined with balloon dilatation. After treatment the symptoms, such as shortness of breath, were markedly improved immediately in all cases. The stenosis degree of patients who were treated with the elec-trocautery needle knife combined with balloon dilatation had better improvement compared with that of those treated with balloon dilatation treatment alone after 3 months (0.45 ± 0.04 vs. 0.67 ± 0.05, p knife combined with balloon dilatation is an effective and safe treatment for tracheal fibrotic stenosis compared with balloon dilatation alone. © 2017 S. Karger AG, Basel.

SU-D-BRB-04: Plan Quality Comparison of Intracranial Stereotactic Radiosurgery (SRS) for Gamma Knife and VMAT Treatments

Energy Technology Data Exchange (ETDEWEB)

Keeling, V; Algan, O; Ahmad, S; Hossain, S [University of Oklahoma Health Sciences Center, Oklahoma City, OK (United States)

2015-06-15

Purpose: To compare treatment plan quality of intracranial stereotactic radiosurgery (SRS) for VMAT (RapidArc) and Gamma Knife (GK) systems. Methods: Ten patients with 24 tumors (seven with 1–2 and three with 4–6 lesions), previously treated with GK 4C (prescription doses ranging from 14–23 Gy) were re-planned for RapidArc. Identical contour sets were kept on MRI images for both plans with tissues assigned a CT number of zero. RapidArc plans were performed using 6 MV flattening-filter-free (FFF) beams with dose rate of 1400 MU/minute using two to eight arcs with the following combinations: 2 full coplanar arcs and the rest non-coplanar half arcs. Beam selection was based on target depth. Areas that penetrated more than 10 cm of tissue were avoided by creating smaller arcs or using avoidance sectors in optimization. Plans were optimized with jaw tracking and a high weighting to the normal-brain-tissue and Normal-Tissue-Objective without compromising PTV coverage. Plans were calculated on a 1 mm grid size using AAA algorithm and then normalized so that 99% of each target volume received the prescription dose. Plan quality was assessed by target coverage using Paddick Conformity Index (PCI), sparing of normal-brain-tissue through analysis of V4, V8, and V12 Gy, and integral dose. Results: In all cases critical structure dose criteria were met. RapidArc had a higher PCI than GK plans for 23 out of 24 lesions. The average PCI was 0.76±0.21 for RapidArc and 0.46±0.20 for GK plans (p≤0.001), respectively. Integral dose and normal-brain-tissue doses for all criteria were lower for RapidArc in nearly all patients. The average ratio of GK to RapidArc plans was 1.28±0.27 (p=0.018), 1.31±0.25 (p=0.017), 1.81±0.43 (p=0.005), and 1.50±0.61 (p=0.006) for V4, V8, and V12 Gy, and integral dose, respectively. Conclusion: VMAT was capable of producing higher quality treatment plans than GK when using optimal beam geometries and proper optimization techniques.

Long-term safety and efficacy of stereotactic radiosurgery for vestibular schwannomas: evaluation of 440 patients more than 10 years after treatment with Gamma Knife surgery.

Science.gov (United States)

Hasegawa, Toshinori; Kida, Yoshihisa; Kato, Takenori; Iizuka, Hiroshi; Kuramitsu, Shunichiro; Yamamoto, Takashi

2013-03-01

Object Little is known about long-term outcomes, including tumor control and adverse radiation effects, in patients harboring vestibular schwannomas (VSs) treated with stereotactic radiosurgery > 10 years previously. The aim of this study was to confirm whether Gamma Knife surgery (GKS) for VSs continues to be safe and effective > 10 years after treatment. Methods A total of 440 patients with VS (including neurofibromatosis Type 2) treated with GKS between May 1991 and December 2000 were evaluable. Of these, 347 patients (79%) underwent GKS as an initial treatment and 93 (21%) had undergone prior resection. Three hundred fifty-eight patients (81%) had a solid tumor and 82 (19%) had a cystic tumor. The median tumor volume was 2.8 cm(3) and the median marginal dose was 12.8 Gy. Results The median follow-up period was 12.5 years. The actuarial 5- and ≥ 10-year progression-free survival was 93% and 92%, respectively. No patient developed treatment failure > 10 years after treatment. According to multivariate analysis, significant factors related to worse progression-free survival included brainstem compression with a deviation of the fourth ventricle (p 13 Gy) and 100% in the low marginal dose group (≤ 13 Gy). Ten patients (2.3%) developed delayed cyst formation. One patient alone developed malignant transformation, indicating an incidence of 0.3%. Conclusions In this study GKS was a safe and effective treatment for the majority of patients followed > 10 years after treatment. Special attention should be paid to cyst formation and malignant transformation as late adverse radiation effects, although they appeared to be rare. However, it is necessary to collect further long-term follow-up data before making conclusions about the long-term safety and efficacy of GKS, especially for young patients with VSs.

Transcatheter arterial chemoembolization (TACE) combined with γ-knife compared to TACE or γ-knife alone for hepatocellular carcinoma.

Science.gov (United States)

Cai, Yeyu; Chang, Qian; Xiao, Enhua; Shang, Quan-Liang; Chen, Zhu

2018-06-01

To compare the clinical efficacies and adverse reactions between transcatheter arterial chemoembolization (TACE), γ-ray 3-dimensional fractionated stereotactic conformal radiotherapy (FSCR), and TACE combined with FSCR for primary hepatocellular carcinoma.The study was approved by the Institutional Review Board, and informed consent was waived due to the retrospective study design. About 121 patients met the inclusion criteria and were included in this study, from March 2008 to January 2010, in the Second Xiangya Hospital. Forty-six patients underwent TACE alone, 36 patients underwent γ-knife alone, and 39 were treated by γ-knife combined with TACE. Short-term effects, overall survival rates, adverse reactions, and survival times were compared between the 3 treatment groups.Short-term effects were observed in 41.3% of the TACE group, 33.3% of the γ-knife group, and 64.1% of the TACE combined γ-knife group (P = .020). Overall survival rates at 6,12, 18, and 24 months were 50%, 34.8%, 28.3%, and 21.7% for the TACE group, 36.1%, 30.6%, 16.7%, and 11.1% for γ-knife group, and 84.6%, 71.8%, 61.5%, and 30.8% for TACE combined γ-knife group, respectively. The differences in the overall survival rates at 6, 12, and 18 months between the 3 groups were statistically significant (P = 0), but the overall survival rates at 24 months in the 3 groups were not significantly different (P = .117). The median survival time was 7 months for the TACE group, 3 months for the γ-knife group, and 20 months for the TACE combined γ-knife group (P = 0). There were statistically significant differences (P = .010) of leukopenia between the 3 groups, and no statistically significant differences of (P > .05) thrombocytopenia, anemia, nausea, vomiting, and liver function lesions.TACE combined with γ-knife for primary hepatocellular carcinoma is superior to TACE or γ-knife alone in short-term and long-term effects. This procedure is a mild, safe, and effective

Knife-ovirt

Energy Technology Data Exchange (ETDEWEB)

2017-07-20

Knife-ovirt is code building on the chef, knife-cloud, fog, rbovirt projects that allows deployment of virtual machines on an ovirt cluster, and immediately bootstrap them into a chef managed infrastructure. (similar to knife-openstack project).

Robotic radiotherapy for prostate cancer with CyberKnife

International Nuclear Information System (INIS)

Hannoun-Levi, J.M.; Benezery, K.; Bondiau, P.Y.; Marcie, S.; Gerard, J.P.; Chamorey, E.

2007-01-01

After 3D conformal radiation therapy without and with modulated intensity, image-guided radiation therapy represents a new technological step. Should prostate cancer treatment using radiotherapy with the CyberKnife robotic system be considered as a new treatment and then investigated through classical clinical research procedure rather than a technical improvement of an already validated treatment? After a general presentation of the CyberKnife, the authors focused on prostate cancer treatment assuming that, according to dosimetric and biological considerations, the treatment by robotic system appears comparable to high dose rate brachytherapy. For prostate cancer treatment are discussed: biological rational for hypo fractionated treatment, high dose rate brachytherapy boost and interest of dose escalation. A comparison is presented between CyberKnife and other validated treatment for prostate cancer (radical prostatectomy, 3D conformal radiation therapy and low and high dose rate brachytherapy). In summary, CyberKnife treatment could be considered as a technical improvement of an already validated treatment in order to deliver a prostate boost after pelvic or peri-prostatic area irradiation. However, the clinical, biological and economical results must be precisely analyzed and could be assessed in the frame of a National Observatory based on shared therapeutic program. (authors)

Initial results of CyberKnife treatment for recurrent previously irradiated head and neck cancer

International Nuclear Information System (INIS)

Himei, Kengo; Katsui, Kuniaki; Yoshida, Atsushi

2003-01-01

The purpose of this study was to evaluate the efficacy of CyberKnife for recurrent previously irradiated head and neck cancer. Thirty-one patients with recurrent previously irradiated head and neck cancer were treated with a CyberKnife from July 1999 to March 2002 at Okayama Kyokuto Hospital were retrospectively studied. The accumulated dose was 28-80 Gy (median 60 Gy). The interval between CyberKnife treatment and previous radiotherapy was 0.4-429.5 months (median 16.3 months). Primary lesions were nasopharynx: 7, maxillary sinus: 6, tongue: 5, ethmoid sinus: 3, and others: 1. The pathology was squamous cell carcinoma: 25, adenoid cystic carcinoma: 4, and others: 2. Symptoms were pain: 8, and nasal bleeding: 2. The prescribed dose was 15.0-40.3 Gy (median 32.3 Gy) as for the marginal dose. The response rate (complete response (CR)+partial response (PR)) and local control rate (CR+PR+no change (NC)) was 74% and 94% respectively. Pain disappeared for 4 cases, relief was obtained for 4 cases and no change for 2 cases and nasal bleeding disappeared for 2 cases for an improvement of symptoms. An adverse effects were observed as mucositis in 5 cases and neck swelling in one case. Prognosis of recurrent previously irradiated head and neck cancer was estimated as poor. Our early experience shows that CyberKnife is expected to be feasible treatment for recurrent previously irradiated head and neck cancer, and for the reduction adverse effects and maintenance of useful quality of life (QOL) for patients. (author)

Conservative management or gamma knife radiosurgery for vestibular schwannoma: tumor growth, symptoms, and quality of life.

Science.gov (United States)

Breivik, Cathrine Nansdal; Nilsen, Roy Miodini; Myrseth, Erling; Pedersen, Paal Henning; Varughese, Jobin K; Chaudhry, Aqeel Asghar; Lund-Johansen, Morten

2013-07-01

There are few reports about the course of vestibular schwannoma (VS) patients following gamma knife radiosurgery (GKRS) compared with the course following conservative management (CM). In this study, we present prospectively collected data of 237 patients with unilateral VS extending outside the internal acoustic canal who received either GKRS (113) or CM (124). The aim was to measure the effect of GKRS compared with the natural course on tumor growth rate and hearing loss. Secondary end points were postinclusion additional treatment, quality of life (QoL), and symptom development. The patients underwent magnetic resonance imaging scans, clinical examination, and QoL assessment by SF-36 questionnaire. Statistics were performed by using Spearman correlation coefficient, Kaplan-Meier plot, Poisson regression model, mixed linear regression models, and mixed logistic regression models. Mean follow-up time was 55.0 months (26.1 standard deviation, range 10-132). Thirteen patients were lost to follow-up. Serviceable hearing was lost in 54 of 71 (76%) (CM) and 34 of 53 (64%) (GKRS) patients during the study period (not significant, log-rank test). There was a significant reduction in tumor volume over time in the GKRS group. The need for treatment following initial GKRS or CM differed at highly significant levels (log-rank test, P < .001). Symptom and QoL development did not differ significantly between the groups. In VS patients, GKRS reduces the tumor growth rate and thereby the incidence rate of new treatment about tenfold. Hearing is lost at similar rates in both groups. Symptoms and QoL seem not to be significantly affected by GKRS.

Which level of treatment quality can be obtained by a robotized irradiation system conducted by image in radiotherapy (CyberKnifeTM)

International Nuclear Information System (INIS)

Al Khawaja, S.

2011-01-01

The CyberKnife TM consists of a 6 MV LINAC mounted on a robotic arm, with six degree of freedom and is coupled to an image guiding system, allowing us to guide the irradiation beams toward the target. The aim is to improve the treatment accuracy and to reduce the irradiation of critical surrounding organs. The treatment is realized by the isotropic convergence of hundreds of orientations for creating up to 1200 mini-beams, which are orientated to the target with sub-millimetric accuracy. This group is completed by a treatment couch, which is also mounted on a robotized arm, that offers 6 additional degrees of freedom, allowing an additional improvement of accuracy, and eliminates the possible limitations. Using its subsystem Synchrony TM , the CyberKnife TM is capable of treating the abdo-thoracic tumors, which move with respiration, by moving dynamically the LINAC to compensate the respiratory motion of the tumors. The high dose level, which is used in this kind of hypo-fractionated treatment, makes the smallest error unacceptable, and needs a very high geometric accuracy with keeping a maximal dosimetric accuracy. Our work is dedicated to evaluate the quality of treatment, in the terms of dosimetric and geometric accuracies. For the different modes of tracking, which are available in the system in static mode, and dynamic mode with respiratory motion tracking. By using different kinds of detectors (ionization chambers, radiochromic films) and three different platforms, which allow simulating simple respiratory motion, real respiratory motion coming from real treated patients, and finally complex motion with hysteresis. The results show clearly the high dosimetric accuracy of the system; this is accompanied by a sub-millimetric geometric accuracy. This geometric accuracy degrades slightly, when treating in dynamic mode with respiratory tracking by Synchrony TM , and especially when the respiratory cycles show a high variation in amplitudes, while the dosimetric

SU-E-T-86: A Systematic Method for GammaKnife SRS Fetal Dose Estimation

Energy Technology Data Exchange (ETDEWEB)

Geneser, S; Paulsson, A; Sneed, P; Braunstein, S; Ma, L [UCSF Comprehensive Cancer Center, San Francisco, CA (United States)

2015-06-15

Purpose: Estimating fetal dose is critical to the decision-making process when radiation treatment is indicated during pregnancy. Fetal doses less than 5cGy confer no measurable non-cancer developmental risks but can produce a threefold increase in developing childhood cancer. In this study, we estimate fetal dose for a patient receiving Gamma Knife stereotactic radiosurgery (GKSRS) treatment and develop a method to estimate dose directly from plan details. Methods: A patient underwent GKSRS on a Perfexion unit for eight brain metastases (two infratentorial and one brainstem). Dose measurements were performed using a CC13, head phantom, and solid water. Superficial doses to the thyroid, sternum, and pelvis were measured using MOSFETs during treatment. Because the fetal dose was too low to accurately measure, we obtained measurements proximally to the isocenter, fitted to an exponential function, and extrapolated dose to the fundus of the uterus, uterine midpoint, and pubic synthesis for both the preliminary and delivered plans. Results: The R-squared fit for the delivered doses was 0.995. The estimated fetal doses for the 72 minute preliminary and 138 minute delivered plans range from 0.0014 to 0.028cGy and 0.07 to 0.38cGy, respectively. MOSFET readings during treatment were just above background for the thyroid and negligible for all inferior positions. The method for estimating fetal dose from plan shot information was within 0.2cGy of the measured values at 14cm cranial to the fetal location. Conclusion: Estimated fetal doses for both the preliminary and delivered plan were well below the 5cGy recommended limit. Due to Pefexion shielding, internal dose is primarily governed by attenuation and drops off exponentially. This is the first work that reports fetal dose for a GK Perfexion unit. Although multiple lesions were treated and the duration of treatment was long, the estimated fetal dose remained very low.

SU-E-T-86: A Systematic Method for GammaKnife SRS Fetal Dose Estimation

International Nuclear Information System (INIS)

Geneser, S; Paulsson, A; Sneed, P; Braunstein, S; Ma, L

2015-01-01

Purpose: Estimating fetal dose is critical to the decision-making process when radiation treatment is indicated during pregnancy. Fetal doses less than 5cGy confer no measurable non-cancer developmental risks but can produce a threefold increase in developing childhood cancer. In this study, we estimate fetal dose for a patient receiving Gamma Knife stereotactic radiosurgery (GKSRS) treatment and develop a method to estimate dose directly from plan details. Methods: A patient underwent GKSRS on a Perfexion unit for eight brain metastases (two infratentorial and one brainstem). Dose measurements were performed using a CC13, head phantom, and solid water. Superficial doses to the thyroid, sternum, and pelvis were measured using MOSFETs during treatment. Because the fetal dose was too low to accurately measure, we obtained measurements proximally to the isocenter, fitted to an exponential function, and extrapolated dose to the fundus of the uterus, uterine midpoint, and pubic synthesis for both the preliminary and delivered plans. Results: The R-squared fit for the delivered doses was 0.995. The estimated fetal doses for the 72 minute preliminary and 138 minute delivered plans range from 0.0014 to 0.028cGy and 0.07 to 0.38cGy, respectively. MOSFET readings during treatment were just above background for the thyroid and negligible for all inferior positions. The method for estimating fetal dose from plan shot information was within 0.2cGy of the measured values at 14cm cranial to the fetal location. Conclusion: Estimated fetal doses for both the preliminary and delivered plan were well below the 5cGy recommended limit. Due to Pefexion shielding, internal dose is primarily governed by attenuation and drops off exponentially. This is the first work that reports fetal dose for a GK Perfexion unit. Although multiple lesions were treated and the duration of treatment was long, the estimated fetal dose remained very low

The Importance of the Conformality, Heterogeneity, and Gradient Indices in Evaluating Gamma Knife Radiosurgery Treatment Plans for Intracranial Meningiomas

International Nuclear Information System (INIS)

Balagamwala, Ehsan H.; Suh, John H.; Barnett, Gene H.; Khan, Mohammad K.; Neyman, Gennady; Cai, Rong S.; Vogelbaum, Michael A.; Novak, Eric; Chao, Samuel T.

2012-01-01

Purpose: To investigate the relationship between the conformality index (CIn), heterogeneity index (HIn), and gradient index (GIn) and the development of toxicity in patients treated with Gamma Knife radiosurgery (GKRS) for intracranial meningiomas. Methods and Materials: Treatment records of patients treated from 1997 to 2009 with at least 6 months of follow-up were reviewed. The following parameters were collected: CIn, HIn, GIn (ratio of the volume receiving half the prescription isodose to the volume receiving the full prescription isodose), brainstem (BS) maximum dose (MD), BS volume receiving ≥12 Gy (V12), optic apparatus (OA) MD, OA V8 Gy, OA V10, number of isocenters, number of isocenters outside target volume, and the occurrence of six toxicities. Univariate and multivariate logistic regression modeling were used for analysis. Results: This study included 145 patients (148 meningiomas) with a median follow-up time of 27 months (range, 6–113.9 months). The majority of meningiomas were located in the skull base (53%). The median prescription dose was 13 Gy (range, 10–24 Gy) to the 51.50% (range, 50–92%) isodose. A lower HIn was correlated with a higher GIn (p = 0.007). CIn was not associated with any toxicity. Higher HIn was associated with the development of dizziness (odds ratio [OR] 1.9; p = 0.02), whereas a lower GIn was associated with motor deficits (OR 0.38; p = 0.04) and auditory changes (OR 0.59; p = 0.04). The OA MD, V8, and V12 were not associated with visual changes, but visual changes were associated with a higher number of isocenters outside the target volume (OR 1.93; p = 0.07). BS V12 was correlated with the development of auditory changes (OR 1.05; p = 0.05), whereas patients with higher BS MD tended to have increased toxicity. Conclusions: Close attention must be paid to all three indices (CIn, HIn, GIn) when optimal treatment plans are determined. We recommend that the target CIn should be ≤2.0, the HIn ≤2.0, and the GIn ≥3

Is it possible to avoid hypopituitarism after irradiation of pituitary adenomas by the Leksell gamma knife?

Science.gov (United States)

Marek, Josef; Jezková, Jana; Hána, Václav; Krsek, Michal; Bandúrová, L'ubomíra; Pecen, Ladislav; Vladyka, Vilibald; Liscák, Roman

2011-02-01

Radiation therapy is one of the treatment options for pituitary adenomas. The most common side effect associated with Leksell gamma knife (LGK) irradiation is the development of hypopituitarism. The aim of this study was to verify that hypopituitarism does not develop if the maximum mean dose to pituitary is kept under 15 Gy and to evaluate the influence of maximum distal infundibulum dose on the development of hypopituitarism. We followed the incidence of hypopituitarism in 85 patients irradiated with LGK in 1993-2003. The patients were divided in two subgroups: the first subgroup followed prospectively (45 patients), irradiated with a mean dose to pituitary 15 Gy. Serum TSH, free thyroxine, testosterone or 17β-oestradiol, IGF1, prolactin and cortisol levels were evaluated before and every 6 months after LGK irradiation. Hypopituitarism after LGK irradiation developed only in 1 out of 45 (2.2%) patients irradiated with a mean dose to pituitary 15 Gy. The radiation dose to the distal infundibulum was found as an independent factor of hypopituitarism with calculated maximum safe dose of 17 Gy. Keeping the mean radiation dose to pituitary under 15 Gy and the dose to the distal infundibulum under 17 Gy prevents the development of hypopituitarism following LGK irradiation.

Serious adverse effects of gamma knife radiosurgery for mesial temporal lobe epilepsy

International Nuclear Information System (INIS)

Kawamura, Tetsuro; Onishi, Hiroaki; Kohda, Yukihiko; Hirose, Genjiro

2012-01-01

Gamma knife radiosurgery (GKRS) for mesial temporal lobe epilepsy (MTLE) has been proposed as an alternative to surgical resection. We report serious adverse effects of the treatment after follow-up periods over 9 years in 11 patients treated with GKRS between 1997 and 2000. The target volume of the entorhinoamygdalohippocampectomy area was 4.8-17.1 ml. Marginal dose of 20-25 Gy to the 50% isodose was delivered. One patient was drowned after suffering seizure 7 months after GKRS. Two patients did not show any reduction in seizure frequency over 9 and 18 months. Both patients requested open surgery and became seizure-free postoperatively. Four of the other eight patients were classified as Engel's class I within 4 years after GKRS. One of the four patients experienced symptomatic radiation-induced cerebral edema transiently, one developed radiation necrosis and required surgery 5 years after GKRS, and one developed cognitive impairment with hemiparesis 10 years after GKRS. Magnetic resonance (MR) imaging showed a large cyst in the irradiated temporal lobe. This patient recovered fully after the cyst excision. Only one patient became seizure-free and antiepileptic drug-free without symptomatic radiation-induced complications. However, MR imaging revealed abnormal enhancement, cyst formation, and diffuse white matter change in the irradiated temporal lobe 9 years after GKRS. GKRS for MTLE causes adverse effects of delayed seizure remission and symptomatic radiation-induced complications. Therefore, GKRS cannot be considered as an ideal alternative to surgery for MTLE. Long-term follow-up studies including MR imaging with contrast medium are required for the patients even after successful control of seizures. (author)

[Research progress of needles with knife-edge for carotid cardiac syndrome].

Science.gov (United States)

Tan, Lingqiong; Zhao, Yanling

2015-04-01

According to topographic anatomy, pathogenesis and by retrieving, summarizing and analyzing literature regarding needle-knife and needles with knife-edge for carotid cardiac syndrome, it is found out that clinical misdiagnosis rate of carotid cardiac syndrome is considerably high. Needle-knife and needles with knife-edge could significantly improve the clinical symptoms of carotid cardiac syndrome, showing characteristic and advantage in treatment, but it is deficient in technique standard and efficacy criteria that should be united and authoritative. Researches regarding pathogenesis of carotid cardiac syndrome are not systematic. Clinical observation regarding long-term efficacy and relapse of needle-knife and needles with knife-edge treatment is rare. It is believed that the awareness on carotid cardiac syndrome should be increased to reduce misdiagnosis; scientific and standardized technique standard and efficacy criteria should be established; systematic and comprehensive researches regarding mechanism of needle-knife and needles with knife-edge for carotid cardiac syndrome should be launched; besides, clinical discussion regarding its long-term efficacy should start to provide a better clinical guideline.

SU-F-T-538: CyberKnife with MLC for Treatment of Large Volume Tumors: A Feasibility Study

Energy Technology Data Exchange (ETDEWEB)

Bichay, T; Mayville, A [Mercy Health, Saint Mary’s, Grand Rapids, MI (United States)

2016-06-15

Purpose: CyberKnife is a well-documented modality for SRS and SBRT treatments. Typical tumors are small and 1–5 fractions are usually used. We determined the feasibility of using CyberKnife, with an InCise multileaf collimator option, for larger tumors undergoing standard dose and fractionation. The intent was to understand the limitation of using this modality for other external beam radiation treatments. Methods: Five tumors from different anatomical sites with volumes from 127.8 cc to 1,320.5 cc were contoured and planned on a Multiplan V5.1 workstation. The target average diameter ranged from 7 cm to 13 cm. The dose fractionation was 1.8–2.0 Gy/fraction and 25–45 fractions for total doses of 45–81 Gy. The sites planned were: pancreas, head and neck, prostate, anal, and esophagus. The plans were optimized to meet conventional dose constraints based on various RTOG protocols for conventional fractionation. Results: The Multiplan treatment planning system successfully generated clinically acceptable plans for all sites studied. The resulting dose distributions achieved reasonable target coverage, all greater than 95%, and satisfactory normal tissue sparing. Treatment times ranged from 9 minutes to 38 minutes, the longest being a head and neck plan with dual targets receiving different doses and with multiple adjacent critical structures. Conclusion: CyberKnife, with the InCise multileaf collimation option, can achieve acceptable dose distributions in large volume tumors treated with conventional dose and fractionation. Although treatment times are greater than conventional accelerator time; target coverage and dose to critical structures can be kept within a clinically acceptable range. While time limitations exist, when necessary CyberKnife can provide an alternative to traditional treatment modalities for large volume tumors.

Effect of Gamma Knife Radiosurgery and Programmed Cell Death 1 Receptor Antagonists on Metastatic Melanoma

Science.gov (United States)

Hubbard, Molly; Nordmann, Tyler; Sperduto, Paul W; Clark, H. Brent; Hunt, Matthew A

2017-01-01

Learning objectives To evaluate radiation-induced changes in patients with brain metastasis secondary to malignant melanoma who received treatment with Gamma Knife radiosurgery (GKRS) and programmed cell death 1 (PD-1) receptor antagonists. Introduction  Stereotactic radiosurgery and chemotherapeutics are used together for treatment of metastatic melanoma and have been linked to delayed radiation-induced vasculitic leukoencephalopathy (DRIVL). There have been reports of more intense interactions with new immunotherapeutics targeting PD-1 receptors, but their interactions have not been well described and may result in an accelerated response to GKRS. Here we present data on subjects treated with this combination from a single institution. Methods Records from patients who underwent treatment for metastatic melanoma to the brain with GKRS from 2011 to 2016 were reviewed. Demographics, date of brain metastasis diagnosis, cause of death when applicable, immunotherapeutics, and imaging findings were recorded. The timing of radiation therapy and medications were also documented.  Results A total of 79 subjects were treated with GKRS, and 66 underwent treatment with both GKRS and immunotherapy. Regarding the 30 patients treated with anti-PD-1 immunotherapy, 21 patients received pembrolizumab, seven patients received nivolumab, and two patients received pembrolizumab and nivolumab. Serial imaging was available for interpretation in 25 patients, with 13 subjects who received GKRS and anti-PD-1 immunotherapy less than six weeks of each other. While four subjects had indeterminate/mixed findings on subsequent magnetic resonance imaging (MRI), nine subjects were noted to have progression. Two of these patients showed progression but subsequent imaging revealed a decrease in progression or improvement on MRI to previously targeted lesions by GKRS. None of the 13 subjects had surgery following their combined therapies. Conclusions This data suggests that there is need for

Effect of beam channel plugging on the outcome of gamma knife radiosurgery for trigeminal neuralgia

International Nuclear Information System (INIS)

Massager, Nicolas; Nissim, Ouzi; Murata, Noriko; Devriendt, Daniel; Desmedt, Francoise; Vanderlinden, Bruno; Regis, Jean; Levivier, Marc

2006-01-01

Purpose: We studied the influence of using plugs for brainstem protection during gamma knife radiosurgery (GKR) of trigeminal neuralgia (TN), with special emphasis on irradiation doses delivered to the trigeminal nerve, pain outcomes, and incidence of trigeminal dysfunction. Methods and Materials: A GKR procedure for TN using an anterior cisternal target and a maximum dose of 90 Gy was performed in 109 patients. For 49 patients, customized beam channel blocking (plugs) were used to reduce the dose delivered to the brainstem. We measured the mean and integrated radiation doses delivered to the trigeminal nerve and the clinical course of patients treated with and without plugs. Results: We found that blocking increases the length of trigeminal nerve exposed to high-dose radiation, resulting in a significantly higher mean dose to the trigeminal nerve. Significantly more of the patients with blocking achieved excellent pain outcomes (84% vs. 62%), but with higher incidences of moderate and bothersome trigeminal nerve dysfunction (37% mild/10% bothersome with plugs vs. 30% mild/2% bothersome without). Conclusions: The use of plugs to protect the brainstem during GKR treatment for TN increases the dose of irradiation delivered to the intracisternal trigeminal nerve root and is associated with an important increase in the incidence of trigeminal nerve dysfunction. Therefore, beam channel blocking should be avoided for 90 Gy-GKR of TN

Usefulness of IT knife nano for endoscopic submucosal dissection of large colo-rectal lesions.

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Suzuki, T; Hara, T; Kitagawa, Y; Yamaguchi, T

2016-01-01

Endoscopic submucosal dissection (ESD) is currently widely conducted for the treatment of early gastrointestinal -cancers. Due to the characteristic anatomy of the large intestine, needle- tip type devices such as Dual knife are mainly used in colorectal ESD. On the other hand, the non- needle-tip type IT knife is a unique device with an insulated tip, and has been reported to be safe, efficacious and speedy when used in gastric ESD. A new model of IT knife, IT knife nano, anticipated to be useful for esophageal and colorectal ESD has become available, but its usefulness has not been reported. Therefore, we performed this study to evaluate the usefulness of IT knife nano for ESD of large colorectal lesions. Previous studies have shown that a tumor size of 40 mm or above significantly prolongs treatment time and is a factor of treatment difficulty. We selected colorectal lesions of 40 mm and above, and compared 32 lesions treated with Dual knife alone before IT knife nano was available (No-IT group) and 40 cases treated with IT knife nano as a second knife after IT knife nano became available (IT group). We assessed en bloc resection rate, complete en bloc resection rate, complication rate and treatment time. The en bloc resection rates in No-IT group and IT group were 100% and 97.5%, respectively, with no significant difference. The respective median treatment time was 70 min and 51 min, and was significantly shortened in IT group (P knife nano in ESD for large colorectal -lesions achieves the same levels of efficacy and safety as conventional device, with the additional merit of shortening treatment time. © Acta Gastro-Enterologica Belgica.

Time-resolved imaging of prompt-gamma rays for proton range verification using a knife-edge slit camera based on digital photon counters

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Cambraia Lopes, Patricia; Clementel, Enrico; Crespo, Paulo; Henrotin, Sebastien; Huizenga, Jan; Janssens, Guillaume; Parodi, Katia; Prieels, Damien; Roellinghoff, Frauke; Smeets, Julien; Stichelbaut, Frederic; Schaart, Dennis R.

2015-08-01

Proton range monitoring may facilitate online adaptive proton therapy and improve treatment outcomes. Imaging of proton-induced prompt gamma (PG) rays using a knife-edge slit collimator is currently under investigation as a potential tool for real-time proton range monitoring. A major challenge in collimated PG imaging is the suppression of neutron-induced background counts. In this work, we present an initial performance test of two knife-edge slit camera prototypes based on arrays of digital photon counters (DPCs). PG profiles emitted from a PMMA target upon irradiation with a 160 MeV proton pencil beams (about 6.5   ×   109 protons delivered in total) were measured using detector modules equipped with four DPC arrays coupled to BGO or LYSO : Ce crystal matrices. The knife-edge slit collimator and detector module were placed at 15 cm and 30 cm from the beam axis, respectively, in all cases. The use of LYSO : Ce enabled time-of-flight (TOF) rejection of background events, by synchronizing the DPC readout electronics with the 106 MHz radiofrequency signal of the cyclotron. The signal-to-background (S/B) ratio of 1.6 obtained with a 1.5 ns TOF window and a 3 MeV-7 MeV energy window was about 3 times higher than that obtained with the same detector module without TOF discrimination and 2 times higher than the S/B ratio obtained with the BGO module. Even 1 mm shifts of the Bragg peak position translated into clear and consistent shifts of the PG profile if TOF discrimination was applied, for a total number of protons as low as about 6.5   ×   108 and a detector surface of 6.6 cm  ×  6.6 cm.

Delayed cerebrospinal fluid leakage 10 years after transsphenoidal surgery and gamma knife surgery. Case report

International Nuclear Information System (INIS)

Ogawa, Yoshikazu; Tominaga, Teiji

2007-01-01

A 38-year-old woman presented with repeated episodes of meningitis. She had undergone transsphenoidal tumor removal followed by gamma knife irradiation in 1994. Complete remission was achieved. Intermittent cerebrospinal fluid (CSF) leakage began in 2004, and transsphenoidal surgery was performed for direct repair of the skull base defect. Operative findings showed that the sellar floor was uncovered, and CSF continuously escaped through the cyanoacrylate polymer framework of the previous repair. Reconstruction used autologous muscle pieces and cyanoacrylate polymer adhesive. The CSF leakage was presumably due to delayed radiation damage to the mucous membrane of the skull base. Several methods for reconstruction of the sellar floor have been proposed, which all rely on tissue regeneration including the arachnoid, dura mater, and mucus membrane of the sphenoidal sinus. Preservation of the arachnoid membrane and minimizing removal of the mucous membrane are essential, especially if postoperative irradiation is anticipated. (author)

Gamma knife radiosurgery for acoustic schwannomas. An analysis of the method of low dose and conformal multiple shots with smaller collimator

International Nuclear Information System (INIS)

Fukuoka, Seiji; Takanashi, Masami; Hojo, Atsufumi; Konishi, Masanori; Nakamura, Hirohiko

2003-01-01

The purpose of this study was to analyze tumor control and possible complications of gamma knife radiosurgery (GKRS) in patients with acoustic schwannomas treated using low marginal dose and conformal multiple shots with smaller collimators to fit irregular tumor shapes. The authors evaluated 183 patients with follow-up periods ranging from 3 to 11 years. Marginal doses were 9 to 15 Gy (median 12 Gy), with corresponding treatment volumes being between 0.1 and 18.7 ml (median 1.8 ml). The number of isocenter varied from 2 to 24 shots (median 9 shots). The actuarial tumor control rate (resection-free survival) was 96.5%. Useful hearing, trigeminal and facial functions were preserved at 75%, 97.4%, and 100%, respectively. Hydrocephalus was recognized in 5.7% of all patients, and seems to occur in cases with medium sized tumors where mild ventricular enlargement is evident prior to treatment. GKRS proves to be a safe and effective therapy for small to medium sized tumors. However, the indication for larger sized tumors (diameter 3+ cm) should be carefully considered, larger tumors being less easy to control and liable to cause ataxia due to transient expansion. (author)

Endoscopic treatment for pancreatic diseases: Needle-knife-guided cannulation via the minor papilla.

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Wang, Wei; Gong, Biao; Jiang, Wei-Song; Liu, Lei; Bielike, Kouken; Xv, Bin; Wu, Yun-Lin

2015-05-21

To determine the efficacy and safety of meticulous cannulation by needle-knife. Three needle-knife procedures were used to facilitate cannulation in cases when standard cannulation techniques failed. A total of 104 cannulations via the minor papilla attempted in 74 patients at our center between January 2008 and June 2014 were retrospectively reviewed. Standard methods were successful in 79 cannulations. Of the 25 cannulations that could not be performed by standard methods, 19 were performed by needle-knife, while 17 (89.5%) were successful. Needle-knife use improved the success rate of cannulation [76.0%, 79/104 vs 92.3%, (79 + 17)/104; P = 0.001]. When the 6 cases not appropriate for needle-knife cannulation were excluded, the success rate was improved further (80.6%, 79/98 vs 98.0%, 96/98; P = 0.000). There were no significant differences in the rates of post-endoscopic retrograde cholangiopancreatography adverse events between the group using standard methods alone and the group using needle-knife after failure of standard methods (4.7% vs 10.5%, P = 0.301). The needle-knife procedure may be an alternative method for improving the success rate of cannulation via the minor papilla, particularly when standard cannulation has failed.

Long-Term Survival and Improved Quality of Life following Multiple Repeat Gamma Knife Radiosurgeries for Recurrent Glioblastoma Multiforme: A Case Report and Review of the Literature

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Erik W. Larson

2013-01-01

Full Text Available The management of glioblastoma multiforme (GBM is in most cases complex and must be specifically tailored to the needs of the patient with the goals of extended survival and improved quality of life. Despite advancements in therapy, treatment outcomes remain almost universally poor. Salvage treatment options for the recurrence of the disease is an area of intense study. The following case highlights the utility of Gamma Knife Radiosurgery (GKRS as a salvage treatment. In this clinical situation, three sequential GKRS treatments led to prolonged survival (beyond four years after diagnosis and improved quality of life in a patient who was unable to receive further chemotherapy regimens and was unwilling to undergo further aggressive resection. To date, there have been few reports of three or more sequential GKRS treatment sessions utilized as salvage therapy for recurrent GBM in patients who can no longer tolerate chemotherapy. This report provides evidence that aggressive local treatment with GKRS at the time of recurrence may be appropriate, depending on a patient’s individual clinical situation, and can lead to prolonged survival and improved quality of life.

CyberKnife SRS: new technologies that enhance the treatment of cancer

International Nuclear Information System (INIS)

Cohen, A.

2008-01-01

The CyberKnife Robotic Radiosurgery System (Accuracy Incorporated, Sunnyvale, CA, USA) is used worldwide to treat tumors and neurological disorders anywhere in the body with sub-millimetre beam delivery accuracy. Accuracy has developed a number of new technologies in recent years to enhance the treatment of cancer patients. Such new technologies include a fast Monte Carlo Dose Calculation algorithm, Sequential Optimization dose planning, the Iris TM Variable Aperture Collimator, an 800 MU/min Linear Accelerator, and Optimized Path Traversal. These technologies enable physicists and physicians to plan treatments quickly and easily and deliver them with unrivalled accuracy and precision

{sup 1}H MR spectroscopy of mesial temporal lobe epilepsies treated with Gamma knife

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Hajek, Milan; Dezortova, Monika [MR Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague (Czech Republic); Center for Cell Therapy and Tissue Repair, V Uvalu 84, 150 00 Prague (Czech Republic); Liscak, Roman; Vymazal, Josef; Vladyka, Vilibald [Department of Stereotactic and Radiation Neurosurgery, Hospital Na Homolce, 151 19, Prague (Czech Republic)

2003-05-01

Proton MR spectroscopy was used to observe long-term post-irradiation metabolic changes in epileptogenic tissue and in the contralateral parts of the brain which are not available with conventional imaging methods. We studied these changes in the temporal lobe in six patients, following radiosurgery on the amygdala and hippocampus. {sup 1}H MR spectroscopy at 1.5 T with short and long echo times (TE=10 and 135 ms) were used together with standard MR imaging sequences (T1-, T2-weighted). The treatment was performed by Leksell Gamma Knife with a dose of 50 Gy to the center and a 50% isodose to the margin of the target, represented by the mean volume of approximately 7.5 ml. Magnetic resonance imaging and MR spectroscopy examinations were performed at least once per year for 3 years. The most significant changes in spectra were observed approximately 1 year after the irradiation when edema in irradiated area was observed and strong signal of lipids was identified. Later, edema and lipid signals disappeared and follow-up was characterized by a decrease of NAA, Cr, and Cho concentrations in the ipsilateral region of the brain to the irradiation (LCModel calculation from voxel of interest 3.8-4.5 ml positioned into the centrum of target volume). The concentration of NAA, Cr, and Cho after radiosurgery was significantly different from control values (p<0.05) and also from concentrations in the contralateral part of the brain (p<0.05). In the contralateral part, the concentration of NAA was significantly increased (p<0.05) (NAA: before treatment 8.81, after treatment 11.33 mM). No radiotoxic changes were observed in the contralateral part of the brain or behind the area of target volume. The MR spectroscopy findings precluded MRI observation and MRS results completed data about the development of radiotoxic changes in the target volume. (orig.)

Characteristic and quality control test in sector collimator gamma knife perfexion at Siloam hospital

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Wesly Manik, Jhon; Hidayanto, Eko; Sutanto, Heri

2017-01-01

In this study conducted to evaluate the collimator 4 mm, 8 mm, 16 mm to determine the level of precision Gamma Knife Perfexion there three years and eight months has not carried out measurements after the first year and verify the alignment of sector 1-8. Measurement with three axes (x-axis, y-axis, z-axis) using the film Gafcromic EBT-3, which will be signaled to a central point in the film to be measured and given a dose of 5 Gy for 10 minutes and then scanned and analyzed using ImageJ softwere 1.50 and dose rate in film comparison with measurent dose rate using electrometer. Alignment of Patient-Positioning System (PPS) with Radiation Focal Point (RFP) determination of quality control testing each collimator 4 mm in the standard test with 0.4 mm passive voice AAPM 54. The results of the standard are still in conformity item 0.21 mm for 4 mm and corelasi dose rate film and measurent using electrometer collimator 4 mm = 0.965, 8 mm = 0.964, 16 mm = 0.959.

Characteristic and quality control test in sector collimator gamma knife perfexion at Siloam hospital

International Nuclear Information System (INIS)

Manik, Jhon Wesly; Hidayanto, Eko; Sutanto, Heri

2017-01-01

In this study conducted to evaluate the collimator 4 mm, 8 mm, 16 mm to determine the level of precision Gamma Knife Perfexion there three years and eight months has not carried out measurements after the first year and verify the alignment of sector 1-8. Measurement with three axes (x-axis, y-axis, z-axis) using the film Gafcromic EBT-3, which will be signaled to a central point in the film to be measured and given a dose of 5 Gy for 10 minutes and then scanned and analyzed using ImageJ softwere 1.50 and dose rate in film comparison with measurent dose rate using electrometer. Alignment of Patient-Positioning System (PPS) with Radiation Focal Point (RFP) determination of quality control testing each collimator 4 mm in the standard test with < 0.1 and > 0.4 mm passive voice AAPM 54. The results of the standard are still in conformity item 0.21 mm for 4 mm and corelasi dose rate film and measurent using electrometer collimator 4 mm = 0.965, 8 mm = 0.964, 16 mm = 0.959. (paper)

Management of Liver Cancer Argon-helium Knife Therapy with Functional Computer Tomography Perfusion Imaging.

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Wang, Hongbo; Shu, Shengjie; Li, Jinping; Jiang, Huijie

2016-02-01

The objective of this study was to observe the change in blood perfusion of liver cancer following argon-helium knife treatment with functional computer tomography perfusion imaging. Twenty-seven patients with primary liver cancer treated with argon-helium knife and were included in this study. Plain computer tomography (CT) and computer tomography perfusion (CTP) imaging were conducted in all patients before and after treatment. Perfusion parameters including blood flows, blood volume, hepatic artery perfusion fraction, hepatic artery perfusion, and hepatic portal venous perfusion were used for evaluating therapeutic effect. All parameters in liver cancer were significantly decreased after argon-helium knife treatment (p knife therapy. Therefore, CTP imaging would play an important role for liver cancer management followed argon-helium knife therapy. © The Author(s) 2014.

Neurological Change after Gamma Knife Radiosurgery for Brain Metastases Involving the Motor Cortex

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Park, Chang-Yong; Choi, Hyun-Yong; Lee, Sang-Ryul; Roh, Tae Hoon; Seo, Mi-Ra

2016-01-01

Background Although Gamma Knife radiosurgery (GKRS) can provide beneficial therapeutic effects for patients with brain metastases, lesions involving the eloquent areas carry a higher risk of neurologic deterioration after treatment, compared to those located in the non-eloquent areas. We aimed to investigate neurological change of the patients with brain metastases involving the motor cortex (MC) and the relevant factors related to neurological deterioration after GKRS. Methods We retrospectively reviewed clinical, radiological and dosimetry data of 51 patients who underwent GKRS for 60 brain metastases involving the MC. Prior to GKRS, motor deficits existed in 26 patients (50.9%). The mean target volume was 3.2 cc (range 0.001–14.1) at the time of GKRS, and the mean prescription dose was 18.6 Gy (range 12–24 Gy). Results The actuarial median survival time from GKRS was 19.2±5.0 months. The calculated local tumor control rates at 6 and 12 months after GKRS were 89.7% and 77.4%, respectively. During the median clinical follow-up duration of 12.3±2.6 months (range 1–54 months), 18 patients (35.3%) experienced new or worsened neurologic deficits with a median onset time of 2.5±0.5 months (range 0.3–9.7 months) after GKRS. Among various factors, prescription dose (>20 Gy) was a significant factor for the new or worsened neurologic deficits in univariate (p=0.027) and multivariate (p=0.034) analysis. The managements of 18 patients were steroid medication (n=10), boost radiation therapy (n=5), and surgery (n=3), and neurological improvement was achieved in 9 (50.0%). Conclusion In our series, prescription dose (>20 Gy) was significantly related to neurological deterioration after GKRS for brain metastases involving the MC. Therefore, we suggest that careful dose adjustment would be required for lesions involving the MC to avoid neurological deterioration requiring additional treatment in the patients with limited life expectancy. PMID:27867921

CyberKnife with Tumor Tracking: An Effective Treatment for High-Risk Surgical Patients with Single Peripheral Lung Metastases

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Snider, James W.; Oermann, Eric K.; Chen, Viola; Rabin, Jennifer; Suy, Simeng; Yu, Xia [Department of Radiation Medicine, Georgetown University Hospital, Washington, DC (United States); Vahdat, Saloomeh [Department of Pathology, Georgetown University Hospital, Washington, DC (United States); Collins, Sean P. [Department of Radiation Medicine, Georgetown University Hospital, Washington, DC (United States); Banovac, Filip [Department of Radiology, Georgetown University Hospital, Washington, DC (United States); Anderson, Eric [Division of Pulmonary, Critical Care and Sleep Medicine, Georgetown University Hospital, Washington, DC (United States); Collins, Brian T., E-mail: collinsb@gunet.georgetown.edu [Department of Radiation Medicine, Georgetown University Hospital, Washington, DC (United States)

2012-06-29

Standard treatment for operable patients with single peripheral lung metastases is metastasectomy. We report mature CyberKnife outcomes for high-risk surgical patients with biopsy proven single peripheral lung metastases. Twenty-four patients (median age 73 years) with a mean maximum tumor diameter of 2.5 cm (range, 0.8–4.5 cm) were treated over a 6-year period extending from September 2004 to September 2010 and followed for a minimum of 1 year or until death. A mean dose of 52 Gy (range, 45–60 Gy) was delivered to the prescription isodose line in three fractions over a 3–11 day period (mean, 7 days). At a median follow-up of 20 months, the 2-year Kaplan–Meier local control and overall survival rates were 87 and 50%, respectively. CyberKnife with fiducial tracking is an effective treatment for high-risk surgical patients with single small peripheral lung metastases. Trials comparing CyberKnife with metastasectomy for operable patients are necessary to confirm equivalence.

Clinical implementation of stereotactic treatment for extracranial lesions with body frame

International Nuclear Information System (INIS)

Sankar, A.; Nehru, R.M.; Malhotra, H.K.; Saju Paul, Sherly; Deshpande, D.D.; Sharma, Vinay; Dinshaw, K.A.

2000-01-01

The technique of Stereotaxy has been very successfully carried out initially with gamma knife and further with the x-knife using linear accelerators for the treatment of tumours in the cranial lesions. This technique has now been extended to the lesions in the thoracic, abdominal and pelvic regions. The methodology adopted to implement this challenging technique and the dosimetry considerations are discussed

Multivoxel proton MRS for differentiation of radiation-induced necrosis and tumor recurrence after gamma knife radiosurgery for brain metastases

International Nuclear Information System (INIS)

Chernov, M.F.; Hayashi, Motohiro; Izawa, Masahiro

2006-01-01

Multivoxel proton magnetic resonance spectroscopy (MRS) was used for differentiation of radiation-induced necrosis and tumor recurrence after gamma knife radiosurgery for intracranial metastases in 33 consecutive cases. All patients presented with enlargement of the treated lesion, increase of perilesional brain edema, and aggravation or appearance of neurological signs and symptoms on average 9.3±4.9 months after primary treatment. Metabolic imaging defined four types of lesions: pure tumor recurrence (11 cases), partial tumor recurrence (11 cases), radiation-induced tumor necrosis (10 cases), and radiation-induced necrosis of the peritumoral brain (1 case). In 1 patient, radiation-induced tumor necrosis was diagnosed 9 months after radiosurgery; however, partial tumor recurrence was identified 6 months later. With the exception of midline shift, which was found to be more typical for radiation-induced necrosis (P<0.01), no one clinical, radiologic, or radiosurgical parameter either at the time of primary treatment or at the time of deterioration showed a statistically significant association with the type of the lesion. Proton MRS-based diagnosis was confirmed histologically in all surgically treated patients (7 cases) and corresponded well to the clinical course in others. In conclusion, multivoxel proton MRS is an effective diagnostic modality for identification of radiation-induced necrosis and tumor recurrence that can be used for monitoring of metabolic changes in intracranial neoplasms after radiosurgical treatment. It can be also helpful for differentiation of radiation-induced necrosis of the tumor and that of the peritumoral brain, which may have important clinical and medicolegal implications. (author)

A simple and efficient methodology to improve geometric accuracy in gamma knife radiation surgery: implementation in multiple brain metastases.

Science.gov (United States)

Karaiskos, Pantelis; Moutsatsos, Argyris; Pappas, Eleftherios; Georgiou, Evangelos; Roussakis, Arkadios; Torrens, Michael; Seimenis, Ioannis

2014-12-01

To propose, verify, and implement a simple and efficient methodology for the improvement of total geometric accuracy in multiple brain metastases gamma knife (GK) radiation surgery. The proposed methodology exploits the directional dependence of magnetic resonance imaging (MRI)-related spatial distortions stemming from background field inhomogeneities, also known as sequence-dependent distortions, with respect to the read-gradient polarity during MRI acquisition. First, an extra MRI pulse sequence is acquired with the same imaging parameters as those used for routine patient imaging, aside from a reversal in the read-gradient polarity. Then, "average" image data are compounded from data acquired from the 2 MRI sequences and are used for treatment planning purposes. The method was applied and verified in a polymer gel phantom irradiated with multiple shots in an extended region of the GK stereotactic space. Its clinical impact in dose delivery accuracy was assessed in 15 patients with a total of 96 relatively small (series. Due to these uncertainties, a considerable underdosage (5%-32% of the prescription dose) was found in 33% of the studied targets. The proposed methodology is simple and straightforward in its implementation. Regarding multiple brain metastases applications, the suggested approach may substantially improve total GK dose delivery accuracy in smaller, outlying targets. Copyright © 2014 Elsevier Inc. All rights reserved.

Validation of a pretreatment delivery quality assurance method for the CyberKnife Synchrony system

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Mastella, E., E-mail: edoardo.mastella@cnao.it [Medical Physics Unit, CNAO Foundation—National Centre for Oncological Hadron Therapy, Pavia I-27100, Italy and Medical Physics Unit, IEO—European Institute of Oncology, Milan I-20141 (Italy); Vigorito, S.; Rondi, E.; Cattani, F. [Medical Physics Unit, IEO—European Institute of Oncology, Milan I-20141 (Italy); Piperno, G.; Ferrari, A.; Strata, E.; Rozza, D. [Department of Radiation Oncology, IEO—European Institute of Oncology, Milan I-20141 (Italy); Jereczek-Fossa, B. A. [Department of Radiation Oncology, IEO—European Institute of Oncology, Milan I-20141, Italy and Department of Oncology and Hematology Oncology, University of Milan, Milan I-20122 (Italy)

2016-08-15

Purpose: To evaluate the geometric and dosimetric accuracies of the CyberKnife Synchrony respiratory tracking system (RTS) and to validate a method for pretreatment patient-specific delivery quality assurance (DQA). Methods: An EasyCube phantom was mounted on the ExacTrac gating phantom, which can move along the superior–inferior (SI) axis of a patient to simulate a moving target. The authors compared dynamic and static measurements. For each case, a Gafchromic EBT3 film was positioned between two slabs of the EasyCube, while a PinPoint ionization chamber was placed in the appropriate space. There were three steps to their evaluation: (1) the field size, the penumbra, and the symmetry of six secondary collimators were measured along the two main orthogonal axes. Dynamic measurements with deliberately simulated errors were also taken. (2) The delivered dose distributions (from step 1) were compared with the planned ones, using the gamma analysis method. The local gamma passing rates were evaluated using three acceptance criteria: 3% local dose difference (LDD)/3 mm, 2%LDD/2 mm, and 3%LDD/1 mm. (3) The DQA plans for six clinical patients were irradiated in different dynamic conditions, to give a total of 19 cases. The measured and planned dose distributions were evaluated with the same gamma-index criteria used in step 2 and the measured chamber doses were compared with the planned mean doses in the sensitive volume of the chamber. Results: (1) A very slight enlargement of the field size and of the penumbra was observed in the SI direction (on average <1 mm), in line with the overall average CyberKnife system error for tracking treatments. (2) Comparison between the planned and the correctly delivered dose distributions confirmed the dosimetric accuracy of the RTS for simple plans. The multicriteria gamma analysis was able to detect the simulated errors, proving the robustness of their method of analysis. (3) All of the DQA clinical plans passed the tests, both in

Assessment and characterization of the total geometric uncertainty in Gamma Knife radiosurgery using polymer gels

International Nuclear Information System (INIS)

Moutsatsos, A.; Karaiskos, P.; Pantelis, E.; Georgiou, E.; Petrokokkinos, L.; Sakelliou, L.; Torrens, M.; Seimenis, I.

2013-01-01

Purpose: This work proposes and implements an experimental methodology, based on polymer gels, for assessing the total geometric uncertainty and characterizing its contributors in Gamma Knife (GK) radiosurgery. Methods: A treatment plan consisting of 26, 4-mm GK single shot dose distributions, covering an extended region of the Leksell stereotactic space, was prepared and delivered to a polymer gel filled polymethyl methacrylate (PMMA) head phantom (16 cm diameter) used to accurately reproduce every link in the GK treatment chain. The center of each shot served as a “control point” in the assessment of the GK total geometric uncertainty, which depends on (a) the spatial dose delivery uncertainty of the PERFEXION GK unit used in this work, (b) the spatial distortions inherent in MR images commonly used for target delineation, and (c) the geometric uncertainty contributor associated with the image registration procedure performed by the Leksell GammaPlan (LGP) treatment planning system (TPS), in the case that registration is directly based on the apparent fiducial locations depicted in each MR image by the N-shaped rods on the Leksell localization box. The irradiated phantom was MR imaged at 1.5 T employing a T2-weighted pulse sequence. Four image series were acquired by alternating the frequency encoding axis and reversing the read gradient polarity, thus allowing the characterization of the MR-related spatial distortions. Results: MR spatial distortions stemming from main field (B 0 ) inhomogeneity as well as from susceptibility and chemical shift phenomena (also known as sequence dependent distortions) were found to be of the order of 0.5 mm, while those owing to gradient nonlinearities (also known as sequence independent distortions) were found to increase with distance from the MR scanner isocenter extending up to 0.47 mm at an Euclidean distance of 69.6 mm. Regarding the LGP image registration procedure, the corresponding average contribution to the total

Assessment and characterization of the total geometric uncertainty in Gamma Knife radiosurgery using polymer gels.

Science.gov (United States)

Moutsatsos, A; Karaiskos, P; Petrokokkinos, L; Sakelliou, L; Pantelis, E; Georgiou, E; Torrens, M; Seimenis, I

2013-03-01

This work proposes and implements an experimental methodology, based on polymer gels, for assessing the total geometric uncertainty and characterizing its contributors in Gamma Knife (GK) radiosurgery. A treatment plan consisting of 26, 4-mm GK single shot dose distributions, covering an extended region of the Leksell stereotactic space, was prepared and delivered to a polymer gel filled polymethyl methacrylate (PMMA) head phantom (16 cm diameter) used to accurately reproduce every link in the GK treatment chain. The center of each shot served as a "control point" in the assessment of the GK total geometric uncertainty, which depends on (a) the spatial dose delivery uncertainty of the PERFEXION GK unit used in this work, (b) the spatial distortions inherent in MR images commonly used for target delineation, and (c) the geometric uncertainty contributor associated with the image registration procedure performed by the Leksell GammaPlan (LGP) treatment planning system (TPS), in the case that registration is directly based on the apparent fiducial locations depicted in each MR image by the N-shaped rods on the Leksell localization box. The irradiated phantom was MR imaged at 1.5 T employing a T2-weighted pulse sequence. Four image series were acquired by alternating the frequency encoding axis and reversing the read gradient polarity, thus allowing the characterization of the MR-related spatial distortions. MR spatial distortions stemming from main field (B0) inhomogeneity as well as from susceptibility and chemical shift phenomena (also known as sequence dependent distortions) were found to be of the order of 0.5 mm, while those owing to gradient nonlinearities (also known as sequence independent distortions) were found to increase with distance from the MR scanner isocenter extending up to 0.47 mm at an Euclidean distance of 69.6 mm. Regarding the LGP image registration procedure, the corresponding average contribution to the total geometric uncertainty ranged from

Analysis of Gafchromic EBT3 film calibration irradiated with gamma rays from different systems: Gamma Knife and Cobalt-60 unit.

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Najafi, Mohsen; Geraily, Ghazale; Shirazi, Alireza; Esfahani, Mahbod; Teimouri, Javad

2017-01-01

In recent years, Gafchromic films are used as an advanced instrument for dosimetry systems. The EBT3 films are a new generation of Gafchromic films. Our main interest is to compare the response of the EBT3 films exposed to gamma rays provided by the Theratron 780C as a conventional radiotherapy system and the Leksell Gamma Knife as a stereotactic radiotherapy system (SRS). Both systems use Cobalt-60 sources, thus using the same energy. However, other factors such as source-to-axis distance, number of sources, dose rate, direction of irradiation, shape of phantom, the field shape of radiation, and different scatter contribution may influence the calibration curve. Calibration curves for the 2 systems were measured and plotted for doses ranging from 0 to 40 Gy at the red and green channels. The best fitting curve was obtained with the Levenberg-Marquardt algorithm. Also, the component of dose uncertainty was obtained for any calibration curve. With the best fitting curve for the EBT3 films, we can use the calibration curve to measure the absolute dose in radiation therapy. Although there is a small deviation between the 2 curves, the p-value at any channel shows no significant difference between the 2 calibration curves. Therefore, the calibration curve for each system can be the same because of minor differences. The results show that with the best fitting curve from measured data, while considering the measurement uncertainties related to them, the EBT3 calibration curve can be used to measure the unknown dose both in SRS and in conventional radiotherapy. Copyright © 2017. Published by Elsevier Inc.

伽玛刀治疗垂体瘤致迟发性动眼神经麻痹1例报告%Delayed oculomotor cranial nerve palsy caused by pituitury tumor after gamma knife stereotactic radiation：a case report

Institute of Scientific and Technical Information of China (English)

吴慧; 刘华; 林洁

2015-01-01

尽管罕见，垂体瘤患者接受伽玛刀治疗后仍可发生颅神经损伤，临床上应予重视。本文报告1例垂体瘤患者在接受伽玛刀治疗后8年出现动眼神经麻痹的临床资料、包括诊断及可能的病理机制。%Patient undergoing gamma knife stereotactic radiation may get cranial nerve palsy though it is rare, to which great attention must be paid. Clinic date on such a case occurred 8 years after the patient was treated with gamma knife stereotactic radiation was reported, in which its diagnose and pathological mechanisms were included.

Effect of treatment modality on the hypothalamic-pituitary function of patients treated with radiation therapy for pituitary adenomas: Hypothalamic dose and endocrine outcomes.

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Andrew eElson

2014-04-01

Full Text Available Background: Both fractionated external beam radiotherapy and single fraction radiosurgery for pituitary adenomas are associated with the risk of hypothalamic-pituitary (HP axis dysfunction.Objective: To analyze the effect of treatment modality (Linac, TomoTherapy, or Gamma Knife on hypothalamic dose and correlate these with HP-Axis deficits after radiotherapy.Methods:Radiation plans of patients treated postoperatively for pituitary adenomas using Linac-based 3D Conformal Radiotherapy (CRT (n=11, TomoTherapy-based Intensity Modulated Radiation Therapy (IMRT (n=10, or Gamma Knife Stereotactic Radiosurgery (SRS(n=12 were retrospectively reviewed. Dose to the hypothalamus was analyzed and postradiotherapy hormone function including growth hormone (GH, thyroid (TSH, adrenal (ACTH, prolactin (PRL, and gonadotropins (FSH/LH were assessed. Results:Post-radiation, 13 of 27 (48% patients eligible for analysis developed at least one new hormone deficit, of which 8 of 11 (72% occurred in the Linac group, 4 of 8 (50% occurred in the TomoTherapy group, and 1 of 8 (12.5% occurred in the Gamma Knife group. Compared with fractionated techniques, Gamma Knife showed improved hypothalamic sparing for DMax Hypo, and V12Gy. For fractionated modalities, TomoTherapy showed improved dosimetric characteristics over Linac-based treatment with hypothalamic DMean (44.8 Gy vs. 26.8 Gy p=0.02, DMax (49.8 Gy vs. 39.1 Gy p=0.04, and V12Gy (100% vs. 76% p=0.004.Conclusion:Maximal dosimetric avoidance of the hypothalamus was achieved using Gamma Knife-based radiosurgery followed by TomoTherapy-based IMRT, and Linac-based 3D conformal radiation therapy, respectively.

Early versus late Gamma Knife radiosurgery following transsphenoidal surgery for nonfunctioning pituitary macroadenomas: a multicenter matched-cohort study.

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Pomeraniec, I Jonathan; Kano, Hideyuki; Xu, Zhiyuan; Nguyen, Brandon; Siddiqui, Zaid A; Silva, Danilo; Sharma, Mayur; Radwan, Hesham; Cohen, Jonathan A; Dallapiazza, Robert F; Iorio-Morin, Christian; Wolf, Amparo; Jane, John A; Grills, Inga S; Mathieu, David; Kondziolka, Douglas; Lee, Cheng-Chia; Wu, Chih-Chun; Cifarelli, Christopher P; Chytka, Tomas; Barnett, Gene H; Lunsford, L Dade; Sheehan, Jason P

2017-10-27

OBJECTIVE Gamma Knife radiosurgery (GKRS) is frequently used to treat residual or recurrent nonfunctioning pituitary macroadenomas. There is no consensus as to whether GKRS should be used early after surgery or if radiosurgery should be withheld until there is evidence of imaging-defined progression of tumor. Given the high incidence of adenoma progression after subtotal resection over time, the present study intended to evaluate the effect of timing of radiosurgery on outcome. METHODS This is a multicenter retrospective review of patients with nonfunctioning pituitary macroadenomas who underwent transsphenoidal surgery followed by GKRS from 1987 to 2015 at 9 institutions affiliated with the International Gamma Knife Research Foundation. Patients were matched by adenoma and radiosurgical parameters and stratified based on the interval between last resection and radiosurgery. Operative results, imaging data, and clinical outcomes were compared across groups following early (≤ 6 months after resection) or late (> 6 months after resection) radiosurgery. RESULTS After matching, 222 patients met the authors' study criteria (from an initial collection of 496 patients) and were grouped based on early (n = 111) or late (n = 111) GKRS following transsphenoidal surgery. There was a greater risk of tumor progression after GKRS (p = 0.013) and residual tumor (p = 0.038) in the late radiosurgical group over a median imaging follow-up period of 68.5 months. No significant difference in the occurrence of post-GKRS endocrinopathy was observed (p = 0.68). Thirty percent of patients without endocrinopathy in the early cohort developed new endocrinopathies during the follow-up period versus 27% in the late cohort (p = 0.84). Fourteen percent of the patients in the early group and 25% of the patients in the late group experienced the resolution of endocrine dysfunction after original presentation (p = 0.32). CONCLUSIONS In this study, early GKRS was associated with a lower risk of

Real-time inverse planning for Gamma KnifeTM radiosurgery

International Nuclear Information System (INIS)

Wu, Q. Jackie; Chankong, Vira; Jitprapaikulsarn, Suradet; Wessels, Barry W.; Einstein, Douglas B.; Mathayomchan, Boonyanit; Kinsella, Timothy J.

2003-01-01

The challenges of real-time Gamma Knife TM inverse planning are the large number of variables involved and the unknown search space a priori. With limited collimator sizes, shots have to be heavily overlapped to form a smooth prescription isodose line that conforms to the irregular target shape. Such overlaps greatly influence the total number of shots per plan, making pre-determination of the total number of shots impractical. However, this total number of shots usually defines the search space, a pre-requisite for most of the optimization methods. Since each shot only covers part of the target, a collection of shots in different locations and various collimator sizes selected makes up the global dose distribution that conforms to the target. Hence, planning or placing these shots is a combinatorial optimization process that is computationally expensive by nature. We have previously developed a theory of shot placement and optimization based on skeletonization. The real-time inverse planning process, reported in this paper, is an expansion and the clinical implementation of this theory. The complete planning process consists of two steps. The first step is to determine an optimal number of shots including locations and sizes and to assign initial collimator size to each of the shots. The second step is to fine-tune the weights using a linear-programming technique. The objective function is to minimize the total dose to the target boundary (i.e., maximize the dose conformity). Results of an ellipsoid test target and ten clinical cases are presented. The clinical cases are also compared with physician's manual plans. The target coverage is more than 99% for manual plans and 97% for all the inverse plans. The RTOG PITV conformity indices for the manual plans are between 1.16 and 3.46, compared to 1.36 to 2.4 for the inverse plans. All the inverse plans are generated in less than 2 min, making real-time inverse planning a reality

Long-term follow-up results of combination therapy of surgery and gamma knife on pituitary tumor

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Ikeda, Hidetoshi; Yoshimoto, Takashi; Shirokura, Hideshi

1997-01-01

Usefulness of the combination therapy for invasive pituitary tumor with surgery and gamma knife (GK) was evaluated on 17 cases followed for >2 years. Tumors involved ACTH cell adenoma, GH cell adenoma, mixed GH and PRL, purihormonal adenoma, gonadotrophic cell adenoma, GH cell adenoma and null cell adenoma, which were divided into I and II group since adverse effects by GK on the normal pituitary tissues could be evaluated according to tumor growth and abnormal hormone secretion. Irradiation was carried out to make the marginal dose of around 30 (15-35) Gy and center dose of 25-70 Gy on the gland, and marginal dose of <10 Gy on optic nerve. After GK, follow-up was done by pituitary hormone values, tests for sight and visual field and MRI examination. Hypopituitarism was seen in 67% with 100% remission of Cushing's disease. MRI revealed that the adenoma changed to fibrosis (type 1) with increasing Gd-enhancement or to cystic necrosis (type 2) without Gd-enhancement. Values for GH, cortisol and ACTH turned to normal ones. Thus the combination therapy was found useful. (K.H.)

Predictive Nomogram for the Durability of Pain Relief From Gamma Knife Radiation Surgery in the Treatment of Trigeminal Neuralgia

International Nuclear Information System (INIS)

Lucas, John T.; Nida, Adrian M.; Isom, Scott; Marshall, Kopriva; Bourland, John D.; Laxton, Adrian W.; Tatter, Stephen B.; Chan, Michael D.

2014-01-01

Purpose: To determine factors associated with the durability of stereotactic radiation surgery (SRS) for treatment of trigeminal neuralgia (TN). Methods and Materials: Between 1999 and 2008, 446 of 777 patients with TN underwent SRS and had evaluable follow-up in our electronic medical records and phone interview records. The median follow-up was 21.2 months. The Barrow Neurologic Institute (BNI) pain scale was used to determine pre- and post-SRS pain. Dose-volume anatomical measurements, Burchiel pain subtype, pain quality, prior procedures, and medication usage were included in this retrospective cohort to identify factors impacting the time to BNI 4-5 pain relapse by using Cox proportional hazard regression. An internet-based nomogram was constructed based on predictive factors of durable relief pre- and posttreatment at 6-month intervals. Results: Rates of freedom from BNI 4-5 failure at 1, 3, and 5 years were 84.5%, 70.4%, and 46.9%, respectively. Pain relief was BNI 1-3 at 1, 3, and 5 years in 86.1%, 74.3%, and 51.3% of type 1 patients; 79.3%, 46.2%, and 29.3% of type 2 patients; and 62.7%, 50.2%, and 25% of atypical facial pain patients. BNI type 1 pain score was achieved at 1, 3, and 5 years in 62.9%, 43.5%, and 22.0% of patients with type 1 pain and in 47.5%, 25.2%, and 9.2% of type 2 patients, respectively. Only 13% of patients with atypical facial pain achieved BNI 1 response; 42% of patients developed post-Gamma Knife radiation surgery (GKRS) trigeminal dysfunction. Multivariate analysis revealed that post-SRS numbness (hazard ratio [HR], 0.47; P<.0001), type 1 (vs type 2) TN (HR, 0.6; P=.02), and improved post-SRS BNI score at 6 months (HR, 0.009; P<.0001) were predictive of a durable pain response. Conclusions: The durability of SRS for TN depends on the presenting Burchiel pain type, the post-SRS BNI score, and the presence of post-SRS facial numbness. The durability of pain relief can be estimated pre- and posttreatment by using our

Predictive Nomogram for the Durability of Pain Relief From Gamma Knife Radiation Surgery in the Treatment of Trigeminal Neuralgia

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Lucas, John T., E-mail: johnthomas75@gmail.com [Department of Radiation Oncology, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina (United States); Nida, Adrian M. [Biomedical Informatics Center, Medical University of South Carolina, Charleston, South Carolina (United States); Isom, Scott [Department of Biostatistical Sciences, Section of Biostatistics, Wake Forest School of Medicine, Winston-Salem, North Carolina (United States); Marshall, Kopriva [Wake Forest School of Medicine, Winston-Salem, North Carolina (United States); Bourland, John D. [Department of Radiation Oncology, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina (United States); Laxton, Adrian W.; Tatter, Stephen B. [Department of Neurosurgery, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina (United States); Chan, Michael D. [Department of Radiation Oncology, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina (United States)

2014-05-01

Purpose: To determine factors associated with the durability of stereotactic radiation surgery (SRS) for treatment of trigeminal neuralgia (TN). Methods and Materials: Between 1999 and 2008, 446 of 777 patients with TN underwent SRS and had evaluable follow-up in our electronic medical records and phone interview records. The median follow-up was 21.2 months. The Barrow Neurologic Institute (BNI) pain scale was used to determine pre- and post-SRS pain. Dose-volume anatomical measurements, Burchiel pain subtype, pain quality, prior procedures, and medication usage were included in this retrospective cohort to identify factors impacting the time to BNI 4-5 pain relapse by using Cox proportional hazard regression. An internet-based nomogram was constructed based on predictive factors of durable relief pre- and posttreatment at 6-month intervals. Results: Rates of freedom from BNI 4-5 failure at 1, 3, and 5 years were 84.5%, 70.4%, and 46.9%, respectively. Pain relief was BNI 1-3 at 1, 3, and 5 years in 86.1%, 74.3%, and 51.3% of type 1 patients; 79.3%, 46.2%, and 29.3% of type 2 patients; and 62.7%, 50.2%, and 25% of atypical facial pain patients. BNI type 1 pain score was achieved at 1, 3, and 5 years in 62.9%, 43.5%, and 22.0% of patients with type 1 pain and in 47.5%, 25.2%, and 9.2% of type 2 patients, respectively. Only 13% of patients with atypical facial pain achieved BNI 1 response; 42% of patients developed post-Gamma Knife radiation surgery (GKRS) trigeminal dysfunction. Multivariate analysis revealed that post-SRS numbness (hazard ratio [HR], 0.47; P<.0001), type 1 (vs type 2) TN (HR, 0.6; P=.02), and improved post-SRS BNI score at 6 months (HR, 0.009; P<.0001) were predictive of a durable pain response. Conclusions: The durability of SRS for TN depends on the presenting Burchiel pain type, the post-SRS BNI score, and the presence of post-SRS facial numbness. The durability of pain relief can be estimated pre- and posttreatment by using our

Analysis of X-knife and surgery in treatment of arteriovenous malformation of brain

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Patel Pooja

2008-01-01

Full Text Available Background: The goal of treatment in arteriovenous malformation (AVM is total obliteration of the AVM, restoration of normal cerebral function, and preservation of life and neurological function. Aim: To analyze the results of X-knife and surgery for AVM of the brain. The endpoints for success or failure were as follows: success was defined as angiographic obliteration and failure as residual lesion, requiring retreatment, or death due to hemorrhage from the AVM. Materials and Methods: From May 2002 to May 2007, 54 patients were enrolled for this study. Grade I AVM was seen in 9%, grade II in 43%, grade III in 26%, grade IV in 9%, and grade V in 13%. Thirty-eight patients were treated by microsurgical resection out of which Grade I was seen in 5 patients, Grade II was seen in 17 patients, Grade III was seen in 9 patients and Grade V was seen in 7 patients. Rest of the sixteen patients were treated by linear accelerator radiosurgery out of which Grade II was seen in 6 patients, Grade III was seen in 5 patients and Grade IV was seen in 5 patients. The follow up was in range of 3-63 months. In follow up, digital subtraction angiography/ magnetic resonance angiography (DSA/MRA was performed 3 months after surgery and 1 year and 2 years after stereotactic radiosurgery (SRS. Results: Among the patients treated with X-knife, 12/16 (75% had proven angiographic obliteration. Complications were seen in 4/16 (25% patients. Among the patients treated with microsurgical resection, 23/38 (61% had proven angiographic obliteration. Complications (both intraoperative and postoperative were seen in 19/38 (50% patients. Conclusions: Sixty-one percent of patients were candidates for surgical resection. X-knife is a good modality of treatment for a low-grade AVM situated in eloquent areas of the brain and also for high-grade AVMs, when the surgical risk and morbidity is high.

Endoscopic needle-knife treatment for symptomatic esophageal Zenker's diverticulum: A meta-analysis and systematic review.

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Li, Lian Yong; Yang, Yong Tao; Qu, Chang Min; Liang, Shu Wen; Zhong, Chang Qing; Wang, Xiao Ying; Chen, Yan; Spandorfer, Robert M; Christofaro, Sarah; Cai, Qiang

2018-04-01

The aim of this study was to assess the efficacy and safety following endoscopic management of Zenker's diverticulum (ZD) using a needle-knife technique. A systematic search of PubMed, Embase and Cochrane library databases was performed. All original studies reporting efficacy and safety of needle-knife technique for treatment of ZD were included. Pooled event rates across studies were expressed with summative statistics. Main outcomes, such as rates of immediate symptomatic response (ISR), adverse events and recurrence, were extracted, pooled and analyzed. Heterogeneity among studies was assessed using the R statistic. The random effects model was used and results were expressed with forest plots and summative statistics. Thirteen studies included 589 patients were enrolled. Pooled event rates for ISR, overall complication, bleeding and perforation were 88% (95% confidence interval [CI] 79-94%), 13% (95% CI 8-22%), 5% (95% CI 3-10%) and 7% (95% CI 4-12%), respectively. The pooled data demonstrated an overall recurrence rate of 14% (95% CI 9-21%). Diverticulum size of at least 4 cm and less than 4 cm demonstrated pooled adverse event rates of 17% (95% CI 10-27%) and 7% (95% CI 2-18%), respectively. When using diverticuloscope as an accessory, pooled ISR and adverse events rates were 84% (95% CI 58-95%) and 10% (95% CI 3-26%), respectively. Flexible endoscopic procedures using needle-knife offers a relatively safe and effective treatment of symptomatic ZD, especially for ZD of <4 cm in diameter. © 2018 Chinese Medical Association Shanghai Branch, Chinese Society of Gastroenterology, Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.

Dose Calculation Accuracy of the Monte Carlo Algorithm for CyberKnife Compared with Other Commercially Available Dose Calculation Algorithms

International Nuclear Information System (INIS)

Sharma, Subhash; Ott, Joseph; Williams, Jamone; Dickow, Danny

2011-01-01

Monte Carlo dose calculation algorithms have the potential for greater accuracy than traditional model-based algorithms. This enhanced accuracy is particularly evident in regions of lateral scatter disequilibrium, which can develop during treatments incorporating small field sizes and low-density tissue. A heterogeneous slab phantom was used to evaluate the accuracy of several commercially available dose calculation algorithms, including Monte Carlo dose calculation for CyberKnife, Analytical Anisotropic Algorithm and Pencil Beam convolution for the Eclipse planning system, and convolution-superposition for the Xio planning system. The phantom accommodated slabs of varying density; comparisons between planned and measured dose distributions were accomplished with radiochromic film. The Monte Carlo algorithm provided the most accurate comparison between planned and measured dose distributions. In each phantom irradiation, the Monte Carlo predictions resulted in gamma analysis comparisons >97%, using acceptance criteria of 3% dose and 3-mm distance to agreement. In general, the gamma analysis comparisons for the other algorithms were <95%. The Monte Carlo dose calculation algorithm for CyberKnife provides more accurate dose distribution calculations in regions of lateral electron disequilibrium than commercially available model-based algorithms. This is primarily because of the ability of Monte Carlo algorithms to implicitly account for tissue heterogeneities, density scaling functions; and/or effective depth correction factors are not required.

Extracranial Facial Nerve Schwannoma Treated by Hypo-fractionated CyberKnife Radiosurgery.

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Sasaki, Ayaka; Miyazaki, Shinichiro; Hori, Tomokatsu

2016-09-21

Facial nerve schwannoma is a rare intracranial tumor. Treatment for this benign tumor has been controversial. Here, we report a case of extracranial facial nerve schwannoma treated successfully by hypo-fractionated CyberKnife (Accuray, Sunnyvale, CA) radiosurgery and discuss the efficacy of this treatment. A 34-year-old female noticed a swelling in her right mastoid process. The lesion enlarged over a seven-month period, and she experienced facial spasm on the right side. She was diagnosed with a facial schwannoma via a magnetic resonance imaging (MRI) scan of the head and neck and was told to wait until the facial nerve palsy subsides. She was referred to our hospital for radiation therapy. We planned a fractionated CyberKnife radiosurgery for three consecutive days. After CyberKnife radiosurgery, the mass in the right parotid gradually decreased in size, and the facial nerve palsy disappeared. At her eight-month follow-up, her facial spasm had completely disappeared. There has been no recurrence and the facial nerve function has been normal. We successfully demonstrated the efficacy of CyberKnife radiosurgery as an alternative treatment that also preserves neurofunction for facial nerve schwannomas.

The treatment for asymptomatic meningiomas in the era of radiosurgery

International Nuclear Information System (INIS)

Iwai, Yoshiyasu; Yamanaka, Kazuhiro; Morikawa, Toshie; Ishiguro, Tomoya; Honda, Yuji; Matsusaka, Yasuhiro; Komiyama, Masaki; Yasui, Toshihiro

2003-01-01

We evaluated the treatment results in asymptomatic meningiomas in the era of radiosurgery. We encountered 56 patients with asymptomatic meningiomas from January, 1994 to December, 2001. There were 16 male patients and 40 female patients. The most common location was the cerebral convexity. We performed gamma knife radiosurgery for three patients after diagnosis of cavernous sinus meningiomas. The other patients were followed-up after diagnosis for a mean follow-up period of 30.8 months (5 months to 8 years). Tumor growth was verified in 25 patients (43%) and two patients (3.7%) suffered neurological deficits. Among the tumor growth patients, operative resection was performed in six patients (11%) and gamma knife radiosurgery was performed in four patients (7.5%). The other patients were placed under observation. We decided the treatment strategy paying attention to the tumor location, tumor growth speed, tumor size and operative difficulty. The tumor growth rate was 0.1 cm/year among the patients with tumor growth. It was 0.72 cm/year (0.02 to 1.54 cm/year) in the operative group, 0.3 cm/year (0.04 to 0.76 cm/year) in the gamma knife radiosurgery group and 0.08 cm/year (0.01 to 0.76 cm/year) in the observed group. One patient suffered procedure-related deterioration of paresis after operation. The treatment of asymptomatic meningiomas must be decided depending on their natural history and locations. We recommend early radiosurgery for cavernous sinus meningiomas. (author)

Plan delivery quality assurance for CyberKnife: Statistical process control analysis of 350 film-based patient-specific QAs.

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Bellec, J; Delaby, N; Jouyaux, F; Perdrieux, M; Bouvier, J; Sorel, S; Henry, O; Lafond, C

2017-07-01

Robotic radiosurgery requires plan delivery quality assurance (DQA) but there has never been a published comprehensive analysis of a patient-specific DQA process in a clinic. We proposed to evaluate 350 consecutive film-based patient-specific DQAs using statistical process control. We evaluated the performance of the process to propose achievable tolerance criteria for DQA validation and we sought to identify suboptimal DQA using control charts. DQAs were performed on a CyberKnife-M6 using Gafchromic-EBT3 films. The signal-to-dose conversion was performed using a multichannel-correction and a scanning protocol that combined measurement and calibration in a single scan. The DQA analysis comprised a gamma-index analysis at 3%/1.5mm and a separate evaluation of spatial and dosimetric accuracy of the plan delivery. Each parameter was plotted on a control chart and control limits were calculated. A capability index (Cpm) was calculated to evaluate the ability of the process to produce results within specifications. The analysis of capability showed that a gamma pass rate of 85% at 3%/1.5mm was highly achievable as acceptance criteria for DQA validation using a film-based protocol (Cpm>1.33). 3.4% of DQA were outside a control limit of 88% for gamma pass-rate. The analysis of the out-of-control DQA helped identify a dosimetric error in our institute for a specific treatment type. We have defined initial tolerance criteria for DQA validations. We have shown that the implementation of a film-based patient-specific DQA protocol with the use of control charts is an effective method to improve patient treatment safety on CyberKnife. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

The Use of Cone Beam Computed Tomography for Image Guided Gamma Knife Stereotactic Radiosurgery: Initial Clinical Evaluation

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Li, Winnie; Cho, Young-Bin [Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Ansell, Steve [Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario (Canada); Laperriere, Normand; Ménard, Cynthia; Millar, Barbara-Ann [Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Zadeh, Gelareh [Division of Neurosurgery, University of Toronto University Health Network, Toronto Western Hospital, Toronto, Ontario (Canada); Macfeeters-Hamilton Centre for Neuro-oncology, Ontario Cancer Institute, Toronto, Ontario (Canada); Kongkham, Paul; Bernstein, Mark [Division of Neurosurgery, University of Toronto University Health Network, Toronto Western Hospital, Toronto, Ontario (Canada); Jaffray, David A. [Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario (Canada); Chung, Caroline, E-mail: caroline.chung.md@gmail.com [Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada)

2016-09-01

Purpose: The present study used cone beam computed tomography (CBCT) to measure the inter- and intrafraction uncertainties for intracranial stereotactic radiosurgery (SRS) using the Leksell Gamma Knife (GK). Methods and Materials: Using a novel CBCT system adapted to the GK radiosurgery treatment unit, CBCT images were acquired immediately before and after treatment for each treatment session within the context of a research ethics board–approved prospective clinical trial. Patients were immobilized in the Leksell coordinate frame (LCF) for both volumetric CBCT imaging and GK-SRS delivery. The relative displacement of the patient's skull to the stereotactic reference (interfraction motion) was measured for each CBCT scan. Differences between the pre- and post-treatment CBCT scans were used to determine the intrafraction motion. Results: We analyzed 20 pre- and 17 post-treatment CBCT scans in 20 LCF patients treated with SRS. The mean translational pretreatment setup error ± standard deviation in the left-right, anteroposterior, and craniocaudal directions was −0.19 ± 0.32, 0.06 ± 0.27, and −0.23 ± 0.2 mm, with a maximum of −0.74, −0.53, and −0.68 mm, respectively. After an average time between the pre- and post-treatment CBCT scans of 82 minutes (range 27-170), the mean intrafraction error ± standard deviation for the LCF was −0.03 ± 0.05, −0.03 ± 0.18, and −0.03 ± 0.12 mm in the left-right, anteroposterior, and craniocaudual direction, respectively. Conclusions: Using CBCT on a prototype image guided GK Perfexion unit, we were able to measure the inter- and intrafraction positional changes for GK-SRS using the invasive frame. In the era of image guided radiation therapy, the use of CBCT image guidance for both frame- and non–frame-based immobilization systems could serve as a useful quality assurance tool. Our preliminary measurements can guide the application of achievable thresholds for inter- and intrafraction

The Use of Cone Beam Computed Tomography for Image Guided Gamma Knife Stereotactic Radiosurgery: Initial Clinical Evaluation

International Nuclear Information System (INIS)

Li, Winnie; Cho, Young-Bin; Ansell, Steve; Laperriere, Normand; Ménard, Cynthia; Millar, Barbara-Ann; Zadeh, Gelareh; Kongkham, Paul; Bernstein, Mark; Jaffray, David A.; Chung, Caroline

2016-01-01

Purpose: The present study used cone beam computed tomography (CBCT) to measure the inter- and intrafraction uncertainties for intracranial stereotactic radiosurgery (SRS) using the Leksell Gamma Knife (GK). Methods and Materials: Using a novel CBCT system adapted to the GK radiosurgery treatment unit, CBCT images were acquired immediately before and after treatment for each treatment session within the context of a research ethics board–approved prospective clinical trial. Patients were immobilized in the Leksell coordinate frame (LCF) for both volumetric CBCT imaging and GK-SRS delivery. The relative displacement of the patient's skull to the stereotactic reference (interfraction motion) was measured for each CBCT scan. Differences between the pre- and post-treatment CBCT scans were used to determine the intrafraction motion. Results: We analyzed 20 pre- and 17 post-treatment CBCT scans in 20 LCF patients treated with SRS. The mean translational pretreatment setup error ± standard deviation in the left-right, anteroposterior, and craniocaudal directions was −0.19 ± 0.32, 0.06 ± 0.27, and −0.23 ± 0.2 mm, with a maximum of −0.74, −0.53, and −0.68 mm, respectively. After an average time between the pre- and post-treatment CBCT scans of 82 minutes (range 27-170), the mean intrafraction error ± standard deviation for the LCF was −0.03 ± 0.05, −0.03 ± 0.18, and −0.03 ± 0.12 mm in the left-right, anteroposterior, and craniocaudual direction, respectively. Conclusions: Using CBCT on a prototype image guided GK Perfexion unit, we were able to measure the inter- and intrafraction positional changes for GK-SRS using the invasive frame. In the era of image guided radiation therapy, the use of CBCT image guidance for both frame- and non–frame-based immobilization systems could serve as a useful quality assurance tool. Our preliminary measurements can guide the application of achievable thresholds for inter- and intrafraction

Stereotactic radiosurgery and fractionated stereotactic radiotherapy for the treatment of acoustic schwannomas: comparative observations of 125 patients treated at one institution

International Nuclear Information System (INIS)

Andrews, David W.; Suarez, Oscar; Goldman, H. Warren; Downes, M. Beverly; Bednarz, Greg; Corn, Benjamin W.; Werner-Wasik, Maria; Rosenstock, Jeffrey; Curran, Walter J.

2001-01-01

Background: Stereotactic radiosurgery (SRS) and, more recently, fractionated stereotactic radiotherapy (SRT) have been recognized as noninvasive alternatives to surgery for the treatment of acoustic schwannomas. We review our experience of acoustic tumor treatments at one institution using a gamma knife for SRS and the first commercial world installation of a dedicated linac for SRT. Methods: Patients were treated with SRS on the gamma knife or SRT on the linac from October 1994 through August 2000. Gamma knife technique involved a fixed-frame multiple shot/high conformality single treatment, whereas linac technique involved daily conventional fraction treatments involving a relocatable frame, fewer isocenters, and high conformality established by noncoplanar arc beam shaping and differential beam weighting. Results: Sixty-nine patients were treated on the gamma knife, and 56 patients were treated on the linac, with 1 NF-2 patient common to both units. Three patients were lost to follow-up, and in the remaining 122 patients, mean follow-up was 119±67 weeks for SRS patients and 115±96 weeks for SRT patients. Tumor control rates were high (≥97%) for sporadic tumors in both groups but lower for NF-2 tumors in the SRT group. Cranial nerve morbidities were comparably low in both groups, with the exception of functional hearing preservation, which was 2.5-fold higher in patients who received conventional fraction SRT. Conclusion: SRS and SRT represent comparable noninvasive treatments for acoustic schwannomas in both sporadic and NF-2 patient groups. At 1-year follow-up, a significantly higher rate of serviceable hearing preservation was achieved in SRT sporadic tumor patients and may therefore be preferable to alternatives including surgery, SRS, or possibly observation in patients with serviceable hearing

Long-term safety and efficacy of Gamma Knife surgery in classical trigeminal neuralgia: a 497-patient historical cohort study.

Science.gov (United States)

Régis, Jean; Tuleasca, Constantin; Resseguier, Noémie; Carron, Romain; Donnet, Anne; Gaudart, Jean; Levivier, Marc

2016-04-01

Gamma Knife surgery (GKS) is one of the surgical alternatives for the treatment of drug-resistant trigeminal neuralgia (TN). This study aims to evaluate the safety and efficacy of GKS in a large population of patients with TN with very long-term clinical follow-up. Between July 1992 and November 2010, 737 patients presenting with TN were treated using GKS. Data were collected prospectively and were further retrospectively evaluated at Timone University Hospital. The frequency and severity of pain, as well as trigeminal nerve function, were evaluated before GKS and regularly thereafter. Radiosurgery using the Gamma Knife (model B, C, 4C, or Perfexion) was performed with the help of both MR and CT targeting. A single 4-mm isocenter was positioned in the cisternal portion of the trigeminal nerve at a median distance of 7.6 mm (range 4-14 mm) anterior to the emergence of the nerve (retrogasserian target). A median maximum dose of 85 Gy (range 70-90 Gy) was prescribed. The safety and efficacy are reported for 497 patients with medically refractory classical TN who were never previously treated by GKS and had a follow-up of at least 1 year. The median age in this series was 68.3 years (range 28.1-93.2 years). The median follow-up period was 43.8 months (range 12-174.4 months). Overall, 456 patients (91.75%) were initially pain free in a median time of 10 days (range 1-180 days). Their actuarial probabilities of remaining pain free without medication at 3, 5, 7, and 10 years were 71.8%, 64.9%, 59.7%, and 45.3%, respectively. One hundred fifty-seven patients (34.4%) who were initially pain free experienced at least 1 recurrence, with a median delay of onset of 24 months (range 0.6-150.1 months). However, the actuarial rate of maintaining pain relief without further surgery was 67.8% at 10 years. The hypesthesia actuarial rate at 5 years was 20.4% and at 7 years reached 21.1%, but remained stable until 14 years with a median delay of onset of 12 months (range 1-65 months

Maintaining knife sharpness in industrial meat cutting: A matter of knife or meat cutter ability.

Science.gov (United States)

Karltun, J; Vogel, K; Bergstrand, M; Eklund, J

2016-09-01

Knife sharpness is imperative in meat cutting. The aim of this study was to compare the impact of knife blade steel quality with meat cutters' individual ability to maintain the cutting edge sharp in an industrial production setting. Twelve meat cutters in two different companies using three different knives during normal production were studied in this quasi-experimental study. Methods included were measuring knife cutting force before and after knife use, time knives were used, ratings of sharpness and discomfort and interviews. Results showed that the meat cutters' skill of maintaining sharpness during work had a much larger effect on knife sharpness during work than the knife steel differences. The ability was also related to feelings of discomfort and to physical exertion. It was found that meat cutters using more knives were more likely to suffer from discomfort in the upper limbs, which is a risk for developing MSD. Copyright © 2016 Elsevier Ltd. All rights reserved.

Long-Term Survival in a Patient with Multiple Brain Metastases from Small-Cell Lung Cancer Treated with Gamma Knife Radiosurgery on Four Occasions: A Case Report

Science.gov (United States)

Elaimy, Ameer L.; Thumma, Sudheer R.; Lamm, Andrew F.; Mackay, Alexander R.; Lamoreaux, Wayne T.; Fairbanks, Robert K.; Demakas, John J.; Cooke, Barton S.; Lee, Christopher M.

2012-01-01

Brain metastases are the most common cancerous neoplasm in the brain. The treatment of these lesions is challenging and often includes a multimodality management approach with whole-brain radiation therapy, stereotactic radiosurgery, and neurosurgery options. Although advances in biomedical imaging technologies and the treatment of extracranial cancer have led to the overall increase in the survival of brain metastases patients, the finding that select patients survive several years remains puzzling. For this reason, we present the case of a 70-year-old patient who was diagnosed with multiple brain metastases from small-cell lung cancer five years ago and is currently alive following treatment with chemotherapy for the primary cancer and whole-brain radiation therapy and Gamma Knife radiosurgery on four separate occasions for the neurological cancer. Since the diagnosis of brain metastases five years ago, the patient's primary cancer has remained controlled. Furthermore, multiple repeat GKRS procedures provided this patient with high levels of local tumor control, which in combination with a stable primary cancer led to an extended period of survival and a highly functional life. Further analysis and clinical research will be valuable in assessing the durability of multiple GKRS for brain metastases patients who experience long-term survival. PMID:23091748

Establishing a process of irradiating small animal brain using a CyberKnife and a microCT scanner

International Nuclear Information System (INIS)

Kim, Haksoo; Welford, Scott; Fabien, Jeffrey; Zheng, Yiran; Yuan, Jake; Brindle, James; Yao, Min; Lo, Simon; Wessels, Barry; Machtay, Mitchell; Sohn, Jason W.; Sloan, Andrew

2014-01-01

Purpose: Establish and validate a process of accurately irradiating small animals using the CyberKnife G4 System (version 8.5) with treatment plans designed to irradiate a hemisphere of a mouse brain based on microCT scanner images. Methods: These experiments consisted of four parts: (1) building a mouse phantom for intensity modulated radiotherapy (IMRT) quality assurance (QA), (2) proving usability of a microCT for treatment planning, (3) fabricating a small animal positioning system for use with the CyberKnife's image guided radiotherapy (IGRT) system, and (4)in vivo verification of targeting accuracy. A set of solid water mouse phantoms was designed and fabricated, with radiochromic films (RCF) positioned in selected planes to measure delivered doses. After down-sampling for treatment planning compatibility, a CT image set of a phantom was imported into the CyberKnife treatment planning system—MultiPlan (ver. 3.5.2). A 0.5 cm diameter sphere was contoured within the phantom to represent a hemispherical section of a mouse brain. A nude mouse was scanned in an alpha cradle using a microCT scanner (cone-beam, 157 × 149 pixels slices, 0.2 mm longitudinal slice thickness). Based on the results of our positional accuracy study, a planning treatment volume (PTV) was created. A stereotactic body mold of the mouse was “printed” using a 3D printer laying UV curable acrylic plastic. Printer instructions were based on exported contours of the mouse's skin. Positional reproducibility in the mold was checked by measuring ten CT scans. To verify accurate dose delivery in vivo, six mice were irradiated in the mold with a 4 mm target contour and a 2 mm PTV margin to 3 Gy and sacrificed within 20 min to avoid DNA repair. The brain was sliced and stained for analysis. Results: For the IMRT QA using a set of phantoms, the planned dose (6 Gy to the calculation point) was compared to the delivered dose measured via film and analyzed using Gamma analysis (3% and 3 mm). A

Establishing a process of irradiating small animal brain using a CyberKnife and a microCT scanner

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Kim, Haksoo; Welford, Scott [Department of Radiation Oncology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 (United States); Fabien, Jeffrey; Zheng, Yiran; Yuan, Jake; Brindle, James; Yao, Min; Lo, Simon; Wessels, Barry; Machtay, Mitchell; Sohn, Jason W., E-mail: jason.sohn@case.edu [Department of Radiation Oncology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 and University Hospitals of Cleveland, 11100 Euclid Avenue, Cleveland, Ohio 44106 (United States); Sloan, Andrew [Department of Neurosurgery, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 (United States)

2014-02-15

Purpose: Establish and validate a process of accurately irradiating small animals using the CyberKnife G4 System (version 8.5) with treatment plans designed to irradiate a hemisphere of a mouse brain based on microCT scanner images. Methods: These experiments consisted of four parts: (1) building a mouse phantom for intensity modulated radiotherapy (IMRT) quality assurance (QA), (2) proving usability of a microCT for treatment planning, (3) fabricating a small animal positioning system for use with the CyberKnife's image guided radiotherapy (IGRT) system, and (4)in vivo verification of targeting accuracy. A set of solid water mouse phantoms was designed and fabricated, with radiochromic films (RCF) positioned in selected planes to measure delivered doses. After down-sampling for treatment planning compatibility, a CT image set of a phantom was imported into the CyberKnife treatment planning system—MultiPlan (ver. 3.5.2). A 0.5 cm diameter sphere was contoured within the phantom to represent a hemispherical section of a mouse brain. A nude mouse was scanned in an alpha cradle using a microCT scanner (cone-beam, 157 × 149 pixels slices, 0.2 mm longitudinal slice thickness). Based on the results of our positional accuracy study, a planning treatment volume (PTV) was created. A stereotactic body mold of the mouse was “printed” using a 3D printer laying UV curable acrylic plastic. Printer instructions were based on exported contours of the mouse's skin. Positional reproducibility in the mold was checked by measuring ten CT scans. To verify accurate dose delivery in vivo, six mice were irradiated in the mold with a 4 mm target contour and a 2 mm PTV margin to 3 Gy and sacrificed within 20 min to avoid DNA repair. The brain was sliced and stained for analysis. Results: For the IMRT QA using a set of phantoms, the planned dose (6 Gy to the calculation point) was compared to the delivered dose measured via film and analyzed using Gamma analysis (3% and 3 mm

Impact on cognitive functions following gamma knife radiosurgery for cerebral arteriovenous malformations

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A Raghunath

2016-01-01

Full Text Available Background: Radiosurgery is an alternative to surgical resection of arteriovenous malformation (AVM. Very few studies have addressed the concern of radiation injury to the brain and its attendant adverse effects on cognitive function. Materials and Methods: This prospective study included all patients who underwent gamma knife radiosurgery (GKRS at our institute for cerebral AVM between 2006 and December 2008 (n = 34. All patients underwent neuropsychological evaluation before the procedure. Neuropsychological evaluation was repeated in eighteen patients 2 years following GKRS. Clinical outcome, AVM obliteration, and factors influencing outcome were analyzed in these eighteen patients. Results: Before GKRS, more than 50% had significant impairment of neuropsychological functions compared to normal population norms. 66.6% achieved the excellent radiosurgical outcome. At 2 years follow-up, patients showed varied improvement in neuropsychological function in various categories. Pretherapeutic median value for percentage perseverative responses was 26.5 and at follow-up, it reduced to 18.2 (P = 0.039. Set shifting improved in 11 patients (61.1%, remained same in 5 patients (27.7%, and deteriorated in two patients (11.1%. Patients with a higher Spetzler-Martin grade AVM demonstrated a significantly more favorable shift in follow-up test values for set shifting function (P = 0.021. Patients with postradiation imaging changes had lesser tendency to improve in neuropsychological performance at follow-up. Conclusions: GKRS has no clinically harmful effect on cognitive and neuropsychological functioning in patients with brain AVM. On the contrary, there is an improvement in majority of patients at 2 years following radiosurgery when nidus is obliterated.

Impact on cognitive functions following gamma knife radiosurgery for cerebral arteriovenous malformations.

Science.gov (United States)

Raghunath, A; Bennett, Niranjana; Arimappamagan, Arivazhagan; Bhat, Dhananjaya I; Srinivas, Dwarakanath; Thennarasu, K; Jamuna, R; Somanna, Sampath

2016-01-01

Radiosurgery is an alternative to surgical resection of arteriovenous malformation (AVM). Very few studies have addressed the concern of radiation injury to the brain and its attendant adverse effects on cognitive function. This prospective study included all patients who underwent gamma knife radiosurgery (GKRS) at our institute for cerebral AVM between 2006 and December 2008 (n = 34). All patients underwent neuropsychological evaluation before the procedure. Neuropsychological evaluation was repeated in eighteen patients 2 years following GKRS. Clinical outcome, AVM obliteration, and factors influencing outcome were analyzed in these eighteen patients. Before GKRS, more than 50% had significant impairment of neuropsychological functions compared to normal population norms. 66.6% achieved the excellent radiosurgical outcome. At 2 years follow-up, patients showed varied improvement in neuropsychological function in various categories. Pretherapeutic median value for percentage perseverative responses was 26.5 and at follow-up, it reduced to 18.2 (P = 0.039). Set shifting improved in 11 patients (61.1%), remained same in 5 patients (27.7%), and deteriorated in two patients (11.1%). Patients with a higher Spetzler-Martin grade AVM demonstrated a significantly more favorable shift in follow-up test values for set shifting function (P = 0.021). Patients with postradiation imaging changes had lesser tendency to improve in neuropsychological performance at follow-up. GKRS has no clinically harmful effect on cognitive and neuropsychological functioning in patients with brain AVM. On the contrary, there is an improvement in majority of patients at 2 years following radiosurgery when nidus is obliterated.

The Shoemaker's Knife

Science.gov (United States)

Thomson, Ian

2010-01-01

Archimedes, the famous Greek mathematician, lived from 287 BCE until approximately 212 BCE. He thought that the figure of two semi-circles on a straight line enclosed by a larger semi-circle resembled a shoemaker's knife. Archimedes called this figure an "arbelos" since arbelos is the Greek word for a shoemaker's knife. The author describes the…

Glycerol rhizotomy versus gamma knife radiosurgery for the treatment of trigeminal neuralgia: An analysis of patients treated at one institution

International Nuclear Information System (INIS)

Henson, Clarissa Febles; Goldman, H. Warren; Rosenwasser, Robert H.; Downes, M. Beverly; Bednarz, Greg; Pequignot, Edward C.; Werner-Wasik, Maria; Curran, Walter J.; Andrews, David W.

2005-01-01

Background: Medically refractory trigeminal neuralgia (TN) has been treated with a variety of minimally invasive techniques, all of which have been compared with microvascular decompression. For patients not considered good surgical candidates, percutaneous retrogasserian glycerol rhizotomy (GR) and gamma knife (GK) radiosurgery are two minimally invasive techniques in common practice worldwide and used routinely at Jefferson Hospital for Neuroscience. Using a common pain scale outcomes questionnaire, we sought to analyze efficacies and morbidities of both treatments. Methods and Materials: Between June 1994 and December 2002, 79 patients were treated with GR and 109 patients underwent GK for the treatment of TN. GR was performed with fluoroscopic guidance as an overnight inpatient procedure. GK was performed using a single 4-mm shot positioned at the root exit zone of the trigeminal nerve. Radiation doses of 70-90 Gy prescribed to the 100% isodose line were used. Treatment outcomes including pain response, pain recurrence, treatment failure, treatment-related side effects, and overall patient satisfaction with GK and GR were compared using a common outcomes scale. Using the Barrow Neurologic Institute pain scale, patients were asked to define their level of pain both before and after treatment: I, no pain and no pain medication required; I, occasional pain not requiring medication; IIIa, no pain and pain medication used; IIIb, some pain adequately controlled with medication; IV, some pain not adequately controlled with medication; and V, severe pain with no relief with medication. We used posttreatment scores of I, II, IIIa, and IIIb to identify treatment success, whereas scores of IV and V were considered treatment failure. Results were compiled from respondents and analyzed using SAS software. Statistical comparisons used log-rank test, univariate and multivariate logistic regression, Fisher's exact test, and Wilcoxon test with significance established at p < 0

Dosimetric factors associated with pituitary function after Gamma Knife Surgery (GKS) of pituitary adenomas.

Science.gov (United States)

Sicignano, Gianluisa; Losa, Marco; del Vecchio, Antonella; Cattaneo, Giovanni Mauro; Picozzi, Piero; Bolognesi, Angelo; Mortini, Pietro; Calandrino, Riccardo

2012-07-01

Gamma Knife Surgery (GKS) can be an adjunctive option to surgery in the case of pituitary adenomas. The effect of dosimetric variables on the incidence of new anterior pituitary deficits after GKS requires better definition. This retrospective study considered 130 patients with a follow up after GKS >6 months. The diagnosis was nonfunctioning pituitary adenoma (NFPA) in 68 patients and secreting pituitary adenoma (SPA) in 62 patients. Median margin dose was 15/25 Gy for NFPA and SPA, respectively. The endocrinological median follow-up was 60 months. Hypopituitarism was defined as a new pituitary deficit in (at least) one of the three hormonal axes (hypogonadism, hypothyroidism and hypoadrenalism). The predictive value of clinical/dosimetric parameters was tested by univariate/multivariate analyses. Sixteen patients (12.3%) showed a new pituitary deficit in one or more axes. Multivariate analysis confirmed that the mean dose to the stalk/pituitary and the amount of healthy tissue within the high dose region were strong independent predictors of pituitary dysfunction; their best cut-off values were around 15.7 Gy, 7.3 Gy and 1.4 cm(3), respectively. Our data showed a dose-dependent incidence of new hormonal deficits after GKS for pituitary adenoma. During planning definition, the risk of hypopituitarism could be reduced using the outlined safe dose-volume values. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Dosimetric factors associated with pituitary function after Gamma Knife Surgery (GKS) of pituitary adenomas

International Nuclear Information System (INIS)

Sicignano, Gianluisa; Losa, Marco; Vecchio, Antonella del; Cattaneo, Giovanni Mauro; Picozzi, Piero; Bolognesi, Angelo; Mortini, Pietro; Calandrino, Riccardo

2012-01-01

Background and purpose: Gamma Knife Surgery (GKS) can be an adjunctive option to surgery in the case of pituitary adenomas. The effect of dosimetric variables on the incidence of new anterior pituitary deficits after GKS requires better definition. Materials and methods: This retrospective study considered 130 patients with a follow up after GKS >6 months. The diagnosis was nonfunctioning pituitary adenoma (NFPA) in 68 patients and secreting pituitary adenoma (SPA) in 62 patients. Median margin dose was 15/25 Gy for NFPA and SPA, respectively. The endocrinological median follow-up was 60 months. Hypopituitarism was defined as a new pituitary deficit in (at least) one of the three hormonal axes (hypogonadism, hypothyroidism and hypoadrenalism). The predictive value of clinical/dosimetric parameters was tested by univariate/multivariate analyses. Results: Sixteen patients (12.3%) showed a new pituitary deficit in one or more axes. Multivariate analysis confirmed that the mean dose to the stalk/pituitary and the amount of healthy tissue within the high dose region were strong independent predictors of pituitary dysfunction; their best cut-off values were around 15.7 Gy, 7.3 Gy and 1.4 cm 3 , respectively. Conclusions: Our data showed a dose-dependent incidence of new hormonal deficits after GKS for pituitary adenoma. During planning definition, the risk of hypopituitarism could be reduced using the outlined safe dose–volume values.

Combination of water-jet dissection and needle-knife as a hybrid knife simplifies endoscopic submucosal dissection.

Science.gov (United States)

Lingenfelder, Tobias; Fischer, Klaus; Sold, Moritz G; Post, Stefan; Enderle, Markus D; Kaehler, Georg F B A

2009-07-01

The safety and efficacy of endoscopic submucosal dissection (ESD) is very dependent on an effective injection beneath the submucosal lamina and on a controlled cutting technique. After our study group demonstrated the efficacy of the HydroJet in needleless submucosal injections under various physical conditions to create a submucosal fluid cushion (Selective tissue elevation by pressure = STEP technique), the next step was to develop a new instrument to combine the capabilities of an IT-Knife with a high-pressure water-jet in a single instrument. In this experimental study, we compared this new instrument with a standard ESD technique. Twelve gastric ESD were performed in six pigs under endotracheal anesthesia. Square areas measuring 4-cm x 4-cm were marked out on the anterior and posterior wall in the corpus-antrum transition region. The HybridKnife was used as an standard needle knife with insulated tip (i.e., the submucosal injection was performed with an injection needle and only the radiofrequency (RF) part of the HybridKnife was used for cutting (conventional technique)) or the HybridKnife was used in all the individual stages of the ESD, making use of the HybridKnife's combined functions (HybridKnife technique). The size of the resected specimens, the operating time, the frequency with which instruments were changed, the number of bleeding episodes, and the number of injuries to the gastric wall together with the subjective overall assessment of the intervention by the operating physician were recorded. The resected specimens were the same size, with average sizes of 16.96 cm(2) and 15.85 cm(2) resp (p = 0.8125). Bleeding episodes have been less frequent in the HybridKnife group (2.83 vs. 3.5; p = 0.5625). The standard knife caused more injuries to the lamina muscularis propria (0.17 vs. 1.33; p = 0.0313). The operating times had a tendency to be shorter with the HybridKnife technique (47.18 vs. 58.32 minute; p = 0.0313). The combination of a needle-knife

[Design and application of silver needle-knife].

Science.gov (United States)

Sun, Guodong; Shi, Bin; Zhang, Benwu; Xu, Haidong

2015-04-01

A silver needle-knife which has the dual function of silver needle and needle-knife is designed. The main components of this silver needle-knife are approximately 50% silver and approximately 50% nichrome. The silver needle-knife is composed of five parts, including needle-knife tail, spiral handle; steering handle, needle-knife body and needle-knife edge. It converges the advantages of needle-knife and silver needle, which can cut loose of diseased tissue and peel adhesion of lesions, but also be heated with moxa cone and thermal therapeutic instrument, and connect with electroacupuncture apparatus. It has the function of warming channel and removing coldness, dispelling wind and eliminating dampness, resolving spasm and relieving pain, dredging the channel and so on. Due to the spiral handle and the steering handle, the operation is easier, which reduces the blindness of cutting and increase the safety. It is mainly used for soft tissue injury, rheumatism and rheumatoid arthritis, as well as degenerative diseases of spine and joint, and it has obvious efficacy on some internal medical diseases.

A treatment planning comparison between a novel rotating gamma system and robotic linear accelerator based intracranial stereotactic radiosurgery/radiotherapy

Science.gov (United States)

Fareed, Muhammad M.; Eldib, Ahmed; Weiss, Stephanie E.; Hayes, Shelly B.; Li, Jinsheng; C-M Ma, Charlie

2018-02-01

To compare the dosimetric parameters of a novel rotating gamma ray system (RGS) with well-established CyberKnife system (CK) for treating malignant brain lesions. RGS has a treatment head of 16 cobalt-60 sources focused to the isocenter, which can rotate 360° on the ring gantry and swing 35° in the superior direction. We compared several dosimetric parameters in 10 patients undergoing brain stereotactic radiosurgery including plan normalization, number of beams and nodes for CK and shots for RGS, collimators used, estimated treatment time, D 2 cm and conformity index (CI) among two modalities. The median plan normalization for RGS was 56.7% versus 68.5% (p  =  0.002) for CK plans. The median number of shots from RGS was 7.5 whereas the median number of beams and nodes for CK was 79.5 and 46. The median collimator’s diameter used was 3.5 mm for RGS as compared to 5 mm for CK (p  =  0.26). Mean D 2 cm was 5.57 Gy for CyberKnife whereas it was 3.11 Gy for RGS (p  =  0.99). For RGS plans, the median CI was 1.4 compared to 1.3 for the CK treatment plans (p  =  0.98). The average minimum and maximum doses to optic chiasm were 21 and 93 cGy for RGS as compared to 32 and 209 cGy for CK whereas these were 0.5 and 364 cGy by RGS and 18 and 399 cGy by CK to brainstem. The mean V12 Gy for brain predicting for radionecrosis with RGS was 3.75 cm3 as compared to 4.09 cm3 with the CK (p  =  0.41). The dosimetric parameters of a novel RGS with a ring type gantry are comparable with CyberKnife, allowing its use for intracranial lesions and is worth exploring in a clinical setting.

Clinical outcomes of brain metastases treated with gamma knife radiosurgery with 3.0 T versus 1.5 T MRI-based treatment planning: have we finally optimised detection of occult brain metastases?

International Nuclear Information System (INIS)

Loganathan, Amritraj G.; Alphonse, Natalie; Chan, Michael D.

2012-01-01

The goal of this study was to determine if clinically relevant endpoints were changed by improved MRI resolution during radiosurgical treatment planning. Between 2003 and 2008, 200 consecutive patients with brain metastases treated with Gamma Knife radiosurgery (GKRS) using either 1.5 T or 3.0 T MRI for radiosurgical treatment planning were retrospectively analysed. The number of previously undetected metastases at time of radiosurgery, distant brain failures, time delay to whole brain radiotherapy (WBRT), overall survival and likelihood of neurological death were determined. Additional metastases were detected in 31.3% and 24.5% of patients at time of radiosurgery with 3.0 T and 1.5 T MRI, respectively (P = 0.27). Patients with multiple metastases at diagnostic scan were more likely to have additional metastases detected by 3.0 T MRI (P < 0.1). Median time to distant brain failure was 4.87 months and 5.43 months for the 3.0 T and 1.5 T cohorts, respectively (P = 0.44). Median time to WBRT was 5.8 months and 5.3 months for the 3.0 T and 1.5 T cohorts, respectively (P = 0.87). Median survival was 6.4 months for the 3.0 T cohort, and 6.1 months for the 1.5 T cohort (P = 0.71). Likelihood of neurological death was 25.3% and 16.7% for the 3.0 and 1.5 T populations, respectively (P = 0.26). The 3.0 T MRI-based treatment planning for GKRS did not appear to affect the likelihood of distant brain failure, the need for WBRT or the likelihood of neurological death in this series.

SU-F-J-166: Volumetric Spatial Distortions Comparison for 1.5 Tesla Versus 3 Tesla MRI for Gamma Knife Radiosurgery Scans Using Frame Marker Fusion and Co-Registration Modes

International Nuclear Information System (INIS)

Neyman, G

2016-01-01

Purpose: To compare typical volumetric spatial distortions for 1.5 Tesla versus 3 Tesla MRI Gamma Knife radiosurgery scans in the frame marker fusion and co-registration frame-less modes. Methods: Quasar phantom by Modus Medical Devices Inc. with GRID image distortion software was used for measurements of volumetric distortions. 3D volumetric T1 weighted scans of the phantom were produced on 1.5 T Avanto and 3 T Skyra MRI Siemens scanners. The analysis was done two ways: for scans with localizer markers from the Leksell frame and relatively to the phantom only (simulated co-registration technique). The phantom grid contained a total of 2002 vertices or control points that were used in the assessment of volumetric geometric distortion for all scans. Results: Volumetric mean absolute spatial deviations relatively to the frame localizer markers for 1.5 and 3 Tesla machine were: 1.39 ± 0.15 and 1.63 ± 0.28 mm with max errors of 1.86 and 2.65 mm correspondingly. Mean 2D errors from the Gamma Plan were 0.3 and 1.0 mm. For simulated co-registration technique the volumetric mean absolute spatial deviations relatively to the phantom for 1.5 and 3 Tesla machine were: 0.36 ± 0.08 and 0.62 ± 0.13 mm with max errors of 0.57 and 1.22 mm correspondingly. Conclusion: Volumetric spatial distortions are lower for 1.5 Tesla versus 3 Tesla MRI machines localized with markers on frames and significantly lower for co-registration techniques with no frame localization. The results show the advantage of using co-registration technique for minimizing MRI volumetric spatial distortions which can be especially important for steep dose gradient fields typically used in Gamma Knife radiosurgery. Consultant for Elekta AB

SU-F-J-166: Volumetric Spatial Distortions Comparison for 1.5 Tesla Versus 3 Tesla MRI for Gamma Knife Radiosurgery Scans Using Frame Marker Fusion and Co-Registration Modes

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Neyman, G [The Cleveland Clinic Foundation, Cleveland, OH (United States)

2016-06-15

Purpose: To compare typical volumetric spatial distortions for 1.5 Tesla versus 3 Tesla MRI Gamma Knife radiosurgery scans in the frame marker fusion and co-registration frame-less modes. Methods: Quasar phantom by Modus Medical Devices Inc. with GRID image distortion software was used for measurements of volumetric distortions. 3D volumetric T1 weighted scans of the phantom were produced on 1.5 T Avanto and 3 T Skyra MRI Siemens scanners. The analysis was done two ways: for scans with localizer markers from the Leksell frame and relatively to the phantom only (simulated co-registration technique). The phantom grid contained a total of 2002 vertices or control points that were used in the assessment of volumetric geometric distortion for all scans. Results: Volumetric mean absolute spatial deviations relatively to the frame localizer markers for 1.5 and 3 Tesla machine were: 1.39 ± 0.15 and 1.63 ± 0.28 mm with max errors of 1.86 and 2.65 mm correspondingly. Mean 2D errors from the Gamma Plan were 0.3 and 1.0 mm. For simulated co-registration technique the volumetric mean absolute spatial deviations relatively to the phantom for 1.5 and 3 Tesla machine were: 0.36 ± 0.08 and 0.62 ± 0.13 mm with max errors of 0.57 and 1.22 mm correspondingly. Conclusion: Volumetric spatial distortions are lower for 1.5 Tesla versus 3 Tesla MRI machines localized with markers on frames and significantly lower for co-registration techniques with no frame localization. The results show the advantage of using co-registration technique for minimizing MRI volumetric spatial distortions which can be especially important for steep dose gradient fields typically used in Gamma Knife radiosurgery. Consultant for Elekta AB.

CyberKnife with Tumor Tracking: An Effective Treatment for High-Risk Surgical Patients with Stage I Non-Small Cell Lung Cancer

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Chen, Viola J.; Oermann, Eric [Department of Radiation Medicine, Georgetown University Hospital, Washington, DC (United States); Vahdat, Saloomeh [Department of Pathology, Georgetown University Hospital, Washington, DC (United States); Rabin, Jennifer; Suy, Simeng; Yu, Xia; Collins, Sean P. [Department of Radiation Medicine, Georgetown University Hospital, Washington, DC (United States); Subramaniam, Deepa [Division of Hematology and Oncology, Georgetown University Hospital, Washington, DC (United States); Banovac, Filip [Department of Radiology, Georgetown University Hospital, Washington, DC (United States); Anderson, Eric [Division of Pulmonary, Critical Care and Sleep Medicine, Georgetown University Hospital, Washington, DC (United States); Collins, Brian T., E-mail: collinsb@gunet.georgetown.edu [Department of Radiation Medicine, Georgetown University Hospital, Washington, DC (United States)

2012-02-01

Published data suggests that wedge resection for stage I non-small cell lung cancer (NSCLC) is associated with improved overall survival compared to stereotactic body radiation therapy. We report CyberKnife outcomes for high-risk surgical patients with biopsy-proven stage I NSCLC. PET/CT imaging was completed for staging. Three-to-five gold fiducial markers were implanted in or near tumors to serve as targeting references. Gross tumor volumes (GTVs) were contoured using lung windows; the margins were expanded by 5 mm to establish the planning treatment volume (PTV). Treatment plans were designed using a mean of 156 pencil beams. Doses delivered to the PTV ranged from 42 to 60 Gy in three fractions. The 30 Gy isodose contour extended at least 1 cm from the GTV to eradicate microscopic disease. Treatments were delivered using the CyberKnife system with tumor tracking. Examination and PET/CT imaging occurred at 3 month follow-up intervals. Forty patients (median age 76) with a median maximum tumor diameter of 2.6 cm (range, 1.4–5.0 cm) and a mean post-bronchodilator percent predicted forced expiratory volume in 1 s (FEV1) of 57% (range, 21–111%) were treated. A median dose of 48 Gy was delivered to the PTV over 3–13 days (median, 7 days). The 30 Gy isodose contour extended a mean 1.9 cm from the GTV. At a median 44 months (range, 12–72 months) follow-up, the 3 year Kaplan–Meier locoregional control and overall survival estimates compare favorably with contemporary wedge resection outcomes at 91 and 75%, respectively. CyberKnife is an effective treatment approach for stage I NSCLC that is similar to wedge resection, eradicating tumors with 1–2 cm margins in order to preserve lung function. Prospective randomized trials comparing CyberKnife with wedge resection are necessary to confirm equivalence.

[Case-control study on needle-knife to cut off the medial branch of the lumbar posterior ramus under C-arm guiding for the treatment of low back pain caused by lumbar facet osteoarthritis].

Science.gov (United States)

Lu, Di; Xu, Wei-xing; Ding, Wei-Guo; Guo, Qiao-Feng; Ma, Gou-ping; Zhu, Wei-min

2013-03-01

To study the clinical efficacy of needle-knife to cut off the medial branch of the lumbar posterior ramus under C-arm guiding to treat low back pain caused by lumbar facet osteoarthritis. From July 2009 to June 2011, 60 patients with low back pain caused by lumbar facet osteoarthritis were reviewed,including 34 males and 26 females, ranging in age from 39 to 73 years old,averaged 61.9 years old; the duration of the disease ranged from 6 to 120 months, with a mean of 18.9 months. All the patients were divided into two groups, 30 patients (18 males and 12 females, ranging in age from 39 to 71 years old, needle-knife group) were treated with needle-knife to cut off medial branch of the lumbar posterior ramus under C -arm guiding and the other 30 patients(16 males and 14 females, ranging in age from 41 to 73 years old, hormone injection group) were treated with hormone injection in lumbar facet joint under C-arm guiding. The preoperative JOA scores and the scores at the 1st, 12th and 26th weeks after treatment were analyzed. Before treatment,the JOA scores between the two groups had no significant difference (P= 0.479); after 1 week of treatment, the JOA scores between the two groups had significant difference (P= 0.040), the improvement rate of hormone injection group was superior than that of the needle-knife group,which were (58.73+/-18.20)% in needle-knife group and (71.10+/-22.19)% in hormone injection group; after 12 weeks of treatment, the JOA scores between the two groups had no significant difference(P=0.569), and the improvement rate between the two groups had no significant difference,which were (50.09+/-19.33)% in the needle-knife group and (48.70+/-18.36)%) in the hormone injection group; after 26 weeks of treatment,the JOA scores between the two groups had significant difference (P=0.000), the improvement rate of hormone injection group was superior than that of the needle-knife group,which were (48.56+/-28.24)% in needle-knife group and (15

Peroral Endoscopic Myotomy in Children: First Experience With a New Triangular Knife.

Science.gov (United States)

Nabi, Zaheer; Ramchandani, Mohan; Chavan, Radhika; Tandan, Manu; Kalapala, Rakesh; Darisetty, Santosh; Reddy, Duvuur Nageshwar

2018-01-01

Peroral endoscopic myotomy (POEM) is a novel treatment modality for achalasia cardia. The procedure is technically challenging and time consuming. Recently, a new triangle tip knife (TTJ) has been introduced, which is equipped with water jet facility. In the present study, we analyzed the feasibility, safety, and efficacy of POEM in children with new triangle tip knife. We retrospectively evaluated the data of children (18 years or younger) who underwent POEM using TTJ knife at our institution. All POEM procedures were performed under general anesthesia in an endoscopy suite. Technical feasibility, safety, efficacy, and procedure duration were assessed. Ten children (4 boys, 6 girls) with mean age of 14.2 ± 2.74 (9-18) years, underwent POEM with TTJ knife. The subtypes of achalasia cardia were type I (4), type II (5), and type III (1). Two children had prior treatment with pneumatic balloon dilatation. POEM was performed via anterior route in majority of children (70%). Mean operating time was 47.6 ± 19.74 (30-98) minutes with no significant difference between anterior and posterior approaches to POEM (48.57 ± 24.01 vs 45.3 ± 3.51; P knife equipped with water jet technique. Integration of water jet reduces procedure duration and technical difficulty with POEM.

Two cases of electrocautery incision therapy using an insulated-tip knife for treatment of symptomatic benign short-segment colonic stenosis following colonic resection.

Science.gov (United States)

Kwon, Jang Hoon; Han, Koon Hee; Kim, Moon Ho; Jang, Woo Sung; Yun, Jung Ho; Song, Yun A; Park, Jong Kyu; Cheon, Gab Jin

2014-09-25

Anastomotic stenosis of the colon is not an uncommon finding; however, its frequency varies from one study to another. Traditionally, postoperative colonic stenosis is managed surgically. However, endoscopic therapy has recently become the preferred treatment modality over traditional surgery. Good short-term success has been achieved with use of endoscopic balloon dilation; however, restenosis may occur over time in 14% to 25% of patients. The current report showed the effectiveness and usefulness of an insulated-tip knife (IT-knife) for electrocautery therapy of a patient with symptomatic anastomotic colonic stenosis.

Neuropsychological outcomes after Gamma Knife radiosurgery for mesial temporal lobe epilepsy: a prospective multicenter study.

Science.gov (United States)

Quigg, Mark; Broshek, Donna K; Barbaro, Nicholas M; Ward, Mariann M; Laxer, Kenneth D; Yan, Guofen; Lamborn, Kathleen

2011-05-01

To assess outcomes of language, verbal memory, cognitive efficiency and mental flexibility, mood, and quality of life (QOL) in a prospective, multicenter pilot study of Gamma Knife radiosurgery (RS) for mesial temporal lobe epilepsy (MTLE). RS, randomized to 20 Gy or 24 Gy comprising 5.5-7.5 ml at the 50% isodose volume, was performed on mesial temporal structures of patients with unilateral MTLE. Neuropsychological evaluations were performed at preoperative baseline, and mean change scores were described at 12 and 24 months postoperatively. QOL data were also available at 36 months. Thirty patients were treated and 26 were available for the final 24-month neuropsychological evaluation. Language (Boston Naming Test), verbal memory (California Verbal Learning Test and Logical Memory subtest of the Wechsler Memory Scale-Revised), cognitive efficiency and mental flexibility (Trail Making Test), and mood (Beck Depression Inventory) did not differ from baseline. QOL scores improved at 24 and 36 months, with those patients attaining seizure remission by month 24s accounting for the majority of the improvement. The serial changes in cognitive outcomes, mood, and QOL are unremarkable following RS for MTLE. RS may provide an alternative to open surgery, especially in those patients at risk of cognitive impairment or who desire a noninvasive alternative to open surgery. Wiley Periodicals, Inc. © 2011 International League Against Epilepsy.

Souvenir knife: a retained transcranial knife blade.

Science.gov (United States)

Davis, Neil L; Kahana, Tzipi; Hiss, Jehuda

2004-09-01

Upon necroscopic examination of a homeless male found comatose in the street and pronounced dead at a medical center 12 hours later, a sharp tip of a knife lodged in the right parietal region of his skull was incidentally discovered. The blade transected the diploe and penetrated the cerebral cortex. Subsequent police investigation revealed that this was the remnant of a stabbing attempt on his life several months prior to his death. The cause of death was determined to be unrelated to the metallic blade fragment, thus making it a truly incidental and rare finding of a "souvenir knife." Nevertheless, since the injury sustained in the stabbing was potentially life threatening, the investigation into that assault was reopened.A case report is presented, along with a brief review of the literature on "souvenir objects."

Characterization of system-related geometric distortions in MR images employed in Gamma Knife radiosurgery applications

Science.gov (United States)

Pappas, E. P.; Seimenis, I.; Moutsatsos, A.; Georgiou, E.; Nomikos, P.; Karaiskos, P.

2016-10-01

This work provides characterization of system-related geometric distortions present in MRIs used in Gamma Knife (GK) stereotactic radiosurgery (SRS) treatment planning. A custom-made phantom, compatible with the Leksell stereotactic frame model G and encompassing 947 control points (CPs), was utilized. MR images were obtained with and without the frame, thus allowing discrimination of frame-induced distortions. In the absence of the frame and following compensation for field inhomogeneities, measured average CP disposition owing to gradient nonlinearities was 0.53 mm. In presence of the frame, contrarily, detected distortion was greatly increased (up to about 5 mm) in the vicinity of the frame base due to eddy currents induced in the closed loop of its aluminum material. Frame-related distortion was obliterated at approximately 90 mm from the frame base. Although the region with the maximum observed distortion may not lie within the GK treatable volume, the presence of the frame results in distortion of the order of 1.5 mm at a 7 cm distance from the center of the Leksell space. Additionally, severe distortions observed outside the treatable volume could possibly impinge on the delivery accuracy mainly by adversely affecting the registration process (e.g. the position of the lower part of the N-shaped fiducials used to define the stereotactic space may be miss-registered). Images acquired with a modified version of the frame developed by replacing its front side with an acrylic bar, thus interrupting the closed aluminum loop and reducing the induced eddy currents, were shown to benefit from relatively reduced distortion. System-related distortion was also identified in patient MR images. Using corresponding CT angiography images as a reference, an offset of 1.1 mm was detected for two vessels lying in close proximity to the frame base, while excellent spatial agreement was observed for a vessel far apart from the frame base.

SU-E-T-104: Development of 3 Dimensional Dosimetry System for Gamma Knife

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