Here, we describe the first patient treated by single session robotic radiosurgery for low risk p... more Here, we describe the first patient treated by single session robotic radiosurgery for low risk prostate cancer. The initial PSA of this 70-year-old patient was 5.05 ng/dl and transrectal biopsy confirmed a Gleason score 3+3=6 tumor. The patient refused a standard surgical and conventional radiation treatment. The combined choline PET/CT before treatment did not show any additional tumor locations and MRI excluded prostate capsule infiltration. Robotic radiosurgery was offered upon the patient's request as an individual treatment attempt. After ultrasound-guided transrectal fiducial implantation, a highly conformal treatment plan was generated and the patient was treated in April 2008 with 19 Gy to the 70% isodose in a single session. The treatment was tolerated very well with the minor dysuretic symptoms during the first two weeks after the procedure. The PSA continuously dropped in the following years and measured 0.07 ng/dl in July 2014. During this period, no significant clinical symptoms were detected, and the patient experienced no rectal or urinary toxicity. This is the first published patient treated with single session prostate radiosurgery, and we believe a prospective trial is warranted to investigate further the options of this attractive treatment concept for low-grade prostate cancer patients.
Here, we describe the first patient treated by single session robotic radiosurgery for low risk p... more Here, we describe the first patient treated by single session robotic radiosurgery for low risk prostate cancer. The initial PSA of this 70-year-old patient was 5.05 ng/dl and transrectal biopsy confirmed a Gleason score 3+3=6 tumor. The patient refused a standard surgical and conventional radiation treatment. The combined choline PET/CT before treatment did not show any additional tumor locations and MRI excluded prostate capsule infiltration. Robotic radiosurgery was offered upon the patient's request as an individual treatment attempt. After ultrasound-guided transrectal fiducial implantation, a highly conformal treatment plan was generated and the patient was treated in April 2008 with 19 Gy to the 70% isodose in a single session. The treatment was tolerated very well with the minor dysuretic symptoms during the first two weeks after the procedure. The PSA continuously dropped in the following years and measured 0.07 ng/dl in July 2014. During this period, no significant clinical symptoms were detected, and the patient experienced no rectal or urinary toxicity. This is the first published patient treated with single session prostate radiosurgery, and we believe a prospective trial is warranted to investigate further the options of this attractive treatment concept for low-grade prostate cancer patients.
Introduction: Medically resistant trigeminal neuralgia (TN) is a well-suited pathology to be trea... more Introduction: Medically resistant trigeminal neuralgia (TN) is a well-suited pathology to be treated by radiosurgery (RS). A significant percentage (60%-70%) of patients is expected to benefit from the RS treatment. Imaging is crucial to identify the target, though unfortunately in some cases the trigeminal nerve could not be visible even in high field magnetic resonance images (MRI). The aim of this work is to develop and relatively validate a method for the atlasbased identification of the target in those cases where the trigeminal nerve is not visible. Material Methods: The proposed method is based on the modification of a previously published approach for functional RS, adapted to the TN. A high resolution, high contrast volumetric T1-MRI atlas was non-rigidly registered to patient T1-MRI. Two patients scanned with a 3T T1weighted-MRI and trigeminal nerve specific MR (Constructive Interference in Steady State-CISS) sequences were considered in this study. In both cases, the right-sided trigeminal nerve was not visible, while it was the contralateral nerve. For one patient, we simulated a potential radiosurgical treatment plan. The atlas-based localization accuracy of the trigeminal nerve was validated in a relative way evaluating the nearby structure continuity and the contralateral nerve localization. Results: The atlas-based fusion showed a high degree of relative accuracy in both cases, suggesting a not ideal coverage of the trigeminal nerve in the simulated treatment plan while opening the way to a possible treatment for both patients. Conclusions: The proposed method holds potential to support the physician to correctly locate the target in those cases where trigeminal nerve is not visible for RS, as well as other therapeutic image-guided applications. Additional cases and further validation in absolute way are needed to definitively assess the accuracy of the method.
Introduccion En el momento actual la RMN se ha convertido en el estudio fundamental para el diagn... more Introduccion En el momento actual la RMN se ha convertido en el estudio fundamental para el diagnostico de la extrusion discal y ha sustituido el TAC y el TAC/mielografia, en el estudio de los tumores espinales, alteraciones congenitas y la mayoria de hernias de disco. Presentamos unos estudios que demuestran que el CT con mielografia puede constituir una alternativa util en algunos de estos pacientes. Material y Metodos Se presentan tres casos en los que el TAC con mielografia permitio definir con claridad alteraciones elusivas en RMN. En los 3 pacientes el TAC con mielografia permitio definir detalles de estructura del hueso y de la compresion radicular no apreciables por RM. Conclusion El TAC con mielografia constituye en ocasiones una tecnica superior a la RMN en el diagnostico de hernias de disco extruidas.
Objective: To develop and integrate a database system into the heterogeneous network environment ... more Objective: To develop and integrate a database system into the heterogeneous network environment of a dedicated radiosurgery treatment center with the goal to facilitate documentation, quality assurance, patient care, and scientific research. Methods: We customized a database on the basis of the commercial software FileMaker Pro® (FileMaker Inc., Santa Clara, CA). The multi-dimensional database system was fully integrated into the network infrastructure of the center. Automated data import and export was established utilizing programmed scripts. Specially trained medical assistants are in charge of the data management. Results: The database stores medical information prospectively and integrates all data of the radiosurgical process, from basic patient data to treatment parameters and follow-up information. All information is quickly available at any workplace in the center. Continuous adaptation of the data management to daily workflows ensures the accuracy and validity of the stored information. Automated scripts generate up-to-date reports and statistical analyses. Conclusions: The database enhances the quality of documentation, treatment, and patient care as well as comfort and efficiency in daily information workflows. To achieve this, the allocation of personnel with responsibility for the database system as well as the data management is crucial.
Radiosurgery is a special treatment method that employs highly focused radiation to destroy tumor... more Radiosurgery is a special treatment method that employs highly focused radiation to destroy tumors with high precision in a single session. A broad base of scientific evidence already exists for the radiosurgical treatment of brain metastases. Recent advances in medical technology now allow radiosurgery to be extended to the spine as well. Selective literature review based on a PubMed search using the search terms stereotaxis, radiosurgery, stereotactic radiotherapy, accuracy, quality assurance, spine, spine metastasis, pain, Novalis, CyberKnife, Synergy, and robotics. We also present and analyze our own data as an illustration of the application of spinal radiosurgery. The literature search identified 20 scientific original publications and one recent review. The data indicate that, within the specific constraints of the method, radiosurgery can arrest the growth of up to 96% of spinal metastases. Durable pain relief can be achieved in patients with tumor-associated pain syndromes....
Computer aided surgery : official journal of the International Society for Computer Aided Surgery, 1999
Complications resulting from imprecise placement of the ventriculoscope and reduced visibility th... more Complications resulting from imprecise placement of the ventriculoscope and reduced visibility through the endoscopic lens under certain conditions during third ventriculostomy have been reported in the literature. The following is a report of our first experience with image-guided endoscopic ventriculostomy. Between September 1996 and October 1997, 11 patients diagnosed with aqueduct stenosis were found to be eligible for image-guided neuroendoscopy. The image-guided system (BrainLab, Heimstetten, Germany) links a freehand probe, tracked by a passive-marker sensor system, to a virtual computer image space. A 4-mm rigid ventriculoscope (Storz Instruments GMBH, Tuttlingen, Germany) was used. Eight patients improved clinically directly after surgery, two patients stabilized, and one patient improved only after insertion of an additional ventriculo-peritoneal shunt. The computer- calculated registration accuracy ranged from 1. 1 to 3.1 mm (median 1.4 mm) using 3-mm computed tomographic...
Journal of applied clinical medical physics / American College of Medical Physics, 2014
CyberKnife spinal radiosurgery suffers from a lack of posterior beams due to workspace limitation... more CyberKnife spinal radiosurgery suffers from a lack of posterior beams due to workspace limitations. This is remedied by a newly available tracking modality for fiducial-free, respiration-compensated spine tracking in prone patient position. We analyzed the potential dosimetric benefit in a planning study. Fourteen exemplary cases were compared in three scenarios: supine (PTV=CTV), prone (PTV=CTV), and prone position with an additional margin (PTV=CTV+2 mm), to incorporate reduced accuracy of respiration-compensated tracking. Target and spinal cord constraints were chosen according to RTOG 0631 protocol for spinal metastases. Plan quality was scored based on four predefined parameters: dose to cord (D0.1cc and D1cc), high dose (V10Gy), and low dose (V4Gy) volume of healthy tissue. Prescription dose was 16 Gy to the highest isodose line encompassing 90% of the target. Results were related to target size and position. All plans fulfilled RTOG 0631 constraints for coverage and dose to c...
Classic radiosurgery is a neurosurgical treatment concept for single-fraction irradiation of cere... more Classic radiosurgery is a neurosurgical treatment concept for single-fraction irradiation of cerebral lesions not amenable to open surgery. Until recently it has been realized mainly by frame-based technologies (Gamma Knife; stereotactic linear accelerators). The CyberKnife described in 1997 is an image-guided frameless robotic technology for whole-body radiosurgery. It can be used for classic single-fraction radiosurgery and for hypofractionated treatments. The CyberKnife treatment procedure is completely non-invasive and can be repeated throughout the body if necessary. Brain metastases are an important and frequently treated indication of modern radiosurgery. Data concerning radiosurgical treatment of brain metastases with the CyberKnife are reviewed. Scientific evidence shows that the full-body applicability of the CyberKnife is not at the expense of an inferior intracranial treatment quality when compared to standard frame-based technology. The clinical results of CyberKnife si...
Computer aided surgery : official journal of the International Society for Computer Aided Surgery, 2011
Optic nerve sheath meningiomas (ONSMs) represent the most challenging lesions involving the optic... more Optic nerve sheath meningiomas (ONSMs) represent the most challenging lesions involving the optic pathways: Microsurgery is not indicated and classical single-stage radiosurgery appears to be too risky due to the expected destruction of the common blood supply with consequent loss of vision. Staged radiosurgery might be one treatment option because it exploits the ability of normal tissues to repair sub-lethal radiation-induced damage, offering a chance to control tumor growth while sparing function. Staged robotic radiosurgery was offered to 5 patients harboring ONSMs with the aim of sparing vision while achieving local growth control. Five patients with ONSM presenting with visual field deficits and loss of visual acuity were treated with staged CyberKnife radiosurgery, receiving 20 Gy in 4 stages (5 Gy per stage). Treatment planning was based on contrast-enhanced thin-slice CT (1.25 mm thickness for the first three cases, 0.5 mm for the last two) and volumetric MR imaging (1.5 T ...
Journal of applied clinical medical physics / American College of Medical Physics, 2011
The image-guided CyberKnife radiosurgery system is apable of tracking spinal targets without fidu... more The image-guided CyberKnife radiosurgery system is apable of tracking spinal targets without fiducial implants. Recently, a new version of this fiducial-free image guidance modality ("enhanced Xsight spine tracking") has been introduced. We assessed the accuracy of this novel technique versus its precursor in a comparative phantom study. The CyberKnife consists of a 6 MV linac on a six-axis robot and a stereoscopic kV image guidance system. An anthropomorphic head-and-neck phantom with a cervical spine section was mounted on the linac nozzle. The robotic manipulator was used to precisely move the phantom to defined positions in the CyberKnife workspace. Multiple stereoscopic images were acquired at different translational and rotational positions. The enhanced Xsight spine tracking readouts were recorded and compared to the nominal phantom position. These tests were repeated with the original Xsight spine tracking version to analyze potential differences. Enhanced Xsight s...
A comparison of treatment parameters and quality of clinical outcome in patients with single brai... more A comparison of treatment parameters and quality of clinical outcome in patients with single brain metastases treated with two different technologies for radiosurgery (Gamma Knife and CyberKnife). Treatment parameters were statistically analyzed. Clinical outcome was assessed by matched-pair analysis based on the treatment device, differences in dose prescription, and the date of the treatment. Patients were matched according to their tumor size, age, gender, primary cancer, and Radiation Therapy Oncology Group score. Survival post-radiosurgery, local and distant tumor control, and complications were analyzed. Predictive factors were investigated. 423 single brain metastases were treated with Gamma Knife and 73 with CyberKnife. Tumor volumes were similar. The parameters minimum tumor dose, maximum tumor dose, prescription isodose volume, conformality index, homogeneity index, volume of tissue receiving a dose of 10 Gy or more were significantly larger in Gamma Knife group. Sixty-thr...
To analyze the feasibility and safety of frameless, image-guided robotic radiosurgery against uve... more To analyze the feasibility and safety of frameless, image-guided robotic radiosurgery against uveal melanoma, we developed a streamlined procedure that is completed within 3 hours under retrobulbar anesthesia without immobilization. Twenty patients (10 men and 10 women) with medium (3-5-mm prominence) and large (>5-mm prominence) unilateral uveal melanomas were treated with a frameless robotic radiosurgery system. Median age was 61 years (range 32-78 years). All patients underwent a single-session procedure beginning with retrobulbar anaesthesia, followed by computerized tomography (CT) scanning that was used in the generation of a treatment plan, and then the delivery of a radiosurgical tumor dose between 18 and 22 Gy to the 70% isodose line. Three-dimensional treatment planning was aimed at securing the optical lens and the optic disc as much as possible. Follow-up occurred at 3, 6, 12, and 18 months after the radiosurgery with clinical, ultrasound, and CT studies. We were able...
Pilocytic astrocytoma (PA) represent a rare indication for Gamma Knife Surgery. Mostly small remn... more Pilocytic astrocytoma (PA) represent a rare indication for Gamma Knife Surgery. Mostly small remnants after surgical debulking are treated. The prognosis depends on specific variants of biological and clinical criteria. In this regard we differentiated two groups of tumors; the so-called 'typical' tumors with a histological grading of WHO Grade I, no prior fractionated radiotherapy and no cystic component and the so called 'atypical' tumors with either a malignant transformation, previous fractionated radiotherapy and/or cystic components. The outcome after GKS was much more favourable for typical PA than for atypical. In typical cases a high tumor control with a very low risk of side effects can be achieved.
The purpose of interstitial radiosurgery is to deliver a necrotizing dose of heat to an accuratel... more The purpose of interstitial radiosurgery is to deliver a necrotizing dose of heat to an accurately defined focal area without damaging adjacent healthy brain tissue. To achieve this, heat at a temperature of 60-100 degrees C is applied via a laser fiber placed stereotactically in the center of the tumor. With the aid of thermosensitive magnetic resonance imaging (MRI), not only can the heat distribution within and around the tumor be measured during treatment, but also the extent of the lesion produced assessed. Interstitial laser thermotherapy (ILTT) performed under MRI monitoring, could become an important interdisciplinary minimally invasive treatment option for patients with brain tumors. Experimental data on the biological effects of interstitial laser therapy on normal brain tissue are not yet available, and only preliminary clinical studies investigating the effects of laser energy on brain tumors have so far been carried out. This overview presents a description of our own i...
Here, we describe the first patient treated by single session robotic radiosurgery for low risk p... more Here, we describe the first patient treated by single session robotic radiosurgery for low risk prostate cancer. The initial PSA of this 70-year-old patient was 5.05 ng/dl and transrectal biopsy confirmed a Gleason score 3+3=6 tumor. The patient refused a standard surgical and conventional radiation treatment. The combined choline PET/CT before treatment did not show any additional tumor locations and MRI excluded prostate capsule infiltration. Robotic radiosurgery was offered upon the patient's request as an individual treatment attempt. After ultrasound-guided transrectal fiducial implantation, a highly conformal treatment plan was generated and the patient was treated in April 2008 with 19 Gy to the 70% isodose in a single session. The treatment was tolerated very well with the minor dysuretic symptoms during the first two weeks after the procedure. The PSA continuously dropped in the following years and measured 0.07 ng/dl in July 2014. During this period, no significant clinical symptoms were detected, and the patient experienced no rectal or urinary toxicity. This is the first published patient treated with single session prostate radiosurgery, and we believe a prospective trial is warranted to investigate further the options of this attractive treatment concept for low-grade prostate cancer patients.
Here, we describe the first patient treated by single session robotic radiosurgery for low risk p... more Here, we describe the first patient treated by single session robotic radiosurgery for low risk prostate cancer. The initial PSA of this 70-year-old patient was 5.05 ng/dl and transrectal biopsy confirmed a Gleason score 3+3=6 tumor. The patient refused a standard surgical and conventional radiation treatment. The combined choline PET/CT before treatment did not show any additional tumor locations and MRI excluded prostate capsule infiltration. Robotic radiosurgery was offered upon the patient's request as an individual treatment attempt. After ultrasound-guided transrectal fiducial implantation, a highly conformal treatment plan was generated and the patient was treated in April 2008 with 19 Gy to the 70% isodose in a single session. The treatment was tolerated very well with the minor dysuretic symptoms during the first two weeks after the procedure. The PSA continuously dropped in the following years and measured 0.07 ng/dl in July 2014. During this period, no significant clinical symptoms were detected, and the patient experienced no rectal or urinary toxicity. This is the first published patient treated with single session prostate radiosurgery, and we believe a prospective trial is warranted to investigate further the options of this attractive treatment concept for low-grade prostate cancer patients.
Introduction: Medically resistant trigeminal neuralgia (TN) is a well-suited pathology to be trea... more Introduction: Medically resistant trigeminal neuralgia (TN) is a well-suited pathology to be treated by radiosurgery (RS). A significant percentage (60%-70%) of patients is expected to benefit from the RS treatment. Imaging is crucial to identify the target, though unfortunately in some cases the trigeminal nerve could not be visible even in high field magnetic resonance images (MRI). The aim of this work is to develop and relatively validate a method for the atlasbased identification of the target in those cases where the trigeminal nerve is not visible. Material Methods: The proposed method is based on the modification of a previously published approach for functional RS, adapted to the TN. A high resolution, high contrast volumetric T1-MRI atlas was non-rigidly registered to patient T1-MRI. Two patients scanned with a 3T T1weighted-MRI and trigeminal nerve specific MR (Constructive Interference in Steady State-CISS) sequences were considered in this study. In both cases, the right-sided trigeminal nerve was not visible, while it was the contralateral nerve. For one patient, we simulated a potential radiosurgical treatment plan. The atlas-based localization accuracy of the trigeminal nerve was validated in a relative way evaluating the nearby structure continuity and the contralateral nerve localization. Results: The atlas-based fusion showed a high degree of relative accuracy in both cases, suggesting a not ideal coverage of the trigeminal nerve in the simulated treatment plan while opening the way to a possible treatment for both patients. Conclusions: The proposed method holds potential to support the physician to correctly locate the target in those cases where trigeminal nerve is not visible for RS, as well as other therapeutic image-guided applications. Additional cases and further validation in absolute way are needed to definitively assess the accuracy of the method.
Introduccion En el momento actual la RMN se ha convertido en el estudio fundamental para el diagn... more Introduccion En el momento actual la RMN se ha convertido en el estudio fundamental para el diagnostico de la extrusion discal y ha sustituido el TAC y el TAC/mielografia, en el estudio de los tumores espinales, alteraciones congenitas y la mayoria de hernias de disco. Presentamos unos estudios que demuestran que el CT con mielografia puede constituir una alternativa util en algunos de estos pacientes. Material y Metodos Se presentan tres casos en los que el TAC con mielografia permitio definir con claridad alteraciones elusivas en RMN. En los 3 pacientes el TAC con mielografia permitio definir detalles de estructura del hueso y de la compresion radicular no apreciables por RM. Conclusion El TAC con mielografia constituye en ocasiones una tecnica superior a la RMN en el diagnostico de hernias de disco extruidas.
Objective: To develop and integrate a database system into the heterogeneous network environment ... more Objective: To develop and integrate a database system into the heterogeneous network environment of a dedicated radiosurgery treatment center with the goal to facilitate documentation, quality assurance, patient care, and scientific research. Methods: We customized a database on the basis of the commercial software FileMaker Pro® (FileMaker Inc., Santa Clara, CA). The multi-dimensional database system was fully integrated into the network infrastructure of the center. Automated data import and export was established utilizing programmed scripts. Specially trained medical assistants are in charge of the data management. Results: The database stores medical information prospectively and integrates all data of the radiosurgical process, from basic patient data to treatment parameters and follow-up information. All information is quickly available at any workplace in the center. Continuous adaptation of the data management to daily workflows ensures the accuracy and validity of the stored information. Automated scripts generate up-to-date reports and statistical analyses. Conclusions: The database enhances the quality of documentation, treatment, and patient care as well as comfort and efficiency in daily information workflows. To achieve this, the allocation of personnel with responsibility for the database system as well as the data management is crucial.
Radiosurgery is a special treatment method that employs highly focused radiation to destroy tumor... more Radiosurgery is a special treatment method that employs highly focused radiation to destroy tumors with high precision in a single session. A broad base of scientific evidence already exists for the radiosurgical treatment of brain metastases. Recent advances in medical technology now allow radiosurgery to be extended to the spine as well. Selective literature review based on a PubMed search using the search terms stereotaxis, radiosurgery, stereotactic radiotherapy, accuracy, quality assurance, spine, spine metastasis, pain, Novalis, CyberKnife, Synergy, and robotics. We also present and analyze our own data as an illustration of the application of spinal radiosurgery. The literature search identified 20 scientific original publications and one recent review. The data indicate that, within the specific constraints of the method, radiosurgery can arrest the growth of up to 96% of spinal metastases. Durable pain relief can be achieved in patients with tumor-associated pain syndromes....
Computer aided surgery : official journal of the International Society for Computer Aided Surgery, 1999
Complications resulting from imprecise placement of the ventriculoscope and reduced visibility th... more Complications resulting from imprecise placement of the ventriculoscope and reduced visibility through the endoscopic lens under certain conditions during third ventriculostomy have been reported in the literature. The following is a report of our first experience with image-guided endoscopic ventriculostomy. Between September 1996 and October 1997, 11 patients diagnosed with aqueduct stenosis were found to be eligible for image-guided neuroendoscopy. The image-guided system (BrainLab, Heimstetten, Germany) links a freehand probe, tracked by a passive-marker sensor system, to a virtual computer image space. A 4-mm rigid ventriculoscope (Storz Instruments GMBH, Tuttlingen, Germany) was used. Eight patients improved clinically directly after surgery, two patients stabilized, and one patient improved only after insertion of an additional ventriculo-peritoneal shunt. The computer- calculated registration accuracy ranged from 1. 1 to 3.1 mm (median 1.4 mm) using 3-mm computed tomographic...
Journal of applied clinical medical physics / American College of Medical Physics, 2014
CyberKnife spinal radiosurgery suffers from a lack of posterior beams due to workspace limitation... more CyberKnife spinal radiosurgery suffers from a lack of posterior beams due to workspace limitations. This is remedied by a newly available tracking modality for fiducial-free, respiration-compensated spine tracking in prone patient position. We analyzed the potential dosimetric benefit in a planning study. Fourteen exemplary cases were compared in three scenarios: supine (PTV=CTV), prone (PTV=CTV), and prone position with an additional margin (PTV=CTV+2 mm), to incorporate reduced accuracy of respiration-compensated tracking. Target and spinal cord constraints were chosen according to RTOG 0631 protocol for spinal metastases. Plan quality was scored based on four predefined parameters: dose to cord (D0.1cc and D1cc), high dose (V10Gy), and low dose (V4Gy) volume of healthy tissue. Prescription dose was 16 Gy to the highest isodose line encompassing 90% of the target. Results were related to target size and position. All plans fulfilled RTOG 0631 constraints for coverage and dose to c...
Classic radiosurgery is a neurosurgical treatment concept for single-fraction irradiation of cere... more Classic radiosurgery is a neurosurgical treatment concept for single-fraction irradiation of cerebral lesions not amenable to open surgery. Until recently it has been realized mainly by frame-based technologies (Gamma Knife; stereotactic linear accelerators). The CyberKnife described in 1997 is an image-guided frameless robotic technology for whole-body radiosurgery. It can be used for classic single-fraction radiosurgery and for hypofractionated treatments. The CyberKnife treatment procedure is completely non-invasive and can be repeated throughout the body if necessary. Brain metastases are an important and frequently treated indication of modern radiosurgery. Data concerning radiosurgical treatment of brain metastases with the CyberKnife are reviewed. Scientific evidence shows that the full-body applicability of the CyberKnife is not at the expense of an inferior intracranial treatment quality when compared to standard frame-based technology. The clinical results of CyberKnife si...
Computer aided surgery : official journal of the International Society for Computer Aided Surgery, 2011
Optic nerve sheath meningiomas (ONSMs) represent the most challenging lesions involving the optic... more Optic nerve sheath meningiomas (ONSMs) represent the most challenging lesions involving the optic pathways: Microsurgery is not indicated and classical single-stage radiosurgery appears to be too risky due to the expected destruction of the common blood supply with consequent loss of vision. Staged radiosurgery might be one treatment option because it exploits the ability of normal tissues to repair sub-lethal radiation-induced damage, offering a chance to control tumor growth while sparing function. Staged robotic radiosurgery was offered to 5 patients harboring ONSMs with the aim of sparing vision while achieving local growth control. Five patients with ONSM presenting with visual field deficits and loss of visual acuity were treated with staged CyberKnife radiosurgery, receiving 20 Gy in 4 stages (5 Gy per stage). Treatment planning was based on contrast-enhanced thin-slice CT (1.25 mm thickness for the first three cases, 0.5 mm for the last two) and volumetric MR imaging (1.5 T ...
Journal of applied clinical medical physics / American College of Medical Physics, 2011
The image-guided CyberKnife radiosurgery system is apable of tracking spinal targets without fidu... more The image-guided CyberKnife radiosurgery system is apable of tracking spinal targets without fiducial implants. Recently, a new version of this fiducial-free image guidance modality ("enhanced Xsight spine tracking") has been introduced. We assessed the accuracy of this novel technique versus its precursor in a comparative phantom study. The CyberKnife consists of a 6 MV linac on a six-axis robot and a stereoscopic kV image guidance system. An anthropomorphic head-and-neck phantom with a cervical spine section was mounted on the linac nozzle. The robotic manipulator was used to precisely move the phantom to defined positions in the CyberKnife workspace. Multiple stereoscopic images were acquired at different translational and rotational positions. The enhanced Xsight spine tracking readouts were recorded and compared to the nominal phantom position. These tests were repeated with the original Xsight spine tracking version to analyze potential differences. Enhanced Xsight s...
A comparison of treatment parameters and quality of clinical outcome in patients with single brai... more A comparison of treatment parameters and quality of clinical outcome in patients with single brain metastases treated with two different technologies for radiosurgery (Gamma Knife and CyberKnife). Treatment parameters were statistically analyzed. Clinical outcome was assessed by matched-pair analysis based on the treatment device, differences in dose prescription, and the date of the treatment. Patients were matched according to their tumor size, age, gender, primary cancer, and Radiation Therapy Oncology Group score. Survival post-radiosurgery, local and distant tumor control, and complications were analyzed. Predictive factors were investigated. 423 single brain metastases were treated with Gamma Knife and 73 with CyberKnife. Tumor volumes were similar. The parameters minimum tumor dose, maximum tumor dose, prescription isodose volume, conformality index, homogeneity index, volume of tissue receiving a dose of 10 Gy or more were significantly larger in Gamma Knife group. Sixty-thr...
To analyze the feasibility and safety of frameless, image-guided robotic radiosurgery against uve... more To analyze the feasibility and safety of frameless, image-guided robotic radiosurgery against uveal melanoma, we developed a streamlined procedure that is completed within 3 hours under retrobulbar anesthesia without immobilization. Twenty patients (10 men and 10 women) with medium (3-5-mm prominence) and large (>5-mm prominence) unilateral uveal melanomas were treated with a frameless robotic radiosurgery system. Median age was 61 years (range 32-78 years). All patients underwent a single-session procedure beginning with retrobulbar anaesthesia, followed by computerized tomography (CT) scanning that was used in the generation of a treatment plan, and then the delivery of a radiosurgical tumor dose between 18 and 22 Gy to the 70% isodose line. Three-dimensional treatment planning was aimed at securing the optical lens and the optic disc as much as possible. Follow-up occurred at 3, 6, 12, and 18 months after the radiosurgery with clinical, ultrasound, and CT studies. We were able...
Pilocytic astrocytoma (PA) represent a rare indication for Gamma Knife Surgery. Mostly small remn... more Pilocytic astrocytoma (PA) represent a rare indication for Gamma Knife Surgery. Mostly small remnants after surgical debulking are treated. The prognosis depends on specific variants of biological and clinical criteria. In this regard we differentiated two groups of tumors; the so-called 'typical' tumors with a histological grading of WHO Grade I, no prior fractionated radiotherapy and no cystic component and the so called 'atypical' tumors with either a malignant transformation, previous fractionated radiotherapy and/or cystic components. The outcome after GKS was much more favourable for typical PA than for atypical. In typical cases a high tumor control with a very low risk of side effects can be achieved.
The purpose of interstitial radiosurgery is to deliver a necrotizing dose of heat to an accuratel... more The purpose of interstitial radiosurgery is to deliver a necrotizing dose of heat to an accurately defined focal area without damaging adjacent healthy brain tissue. To achieve this, heat at a temperature of 60-100 degrees C is applied via a laser fiber placed stereotactically in the center of the tumor. With the aid of thermosensitive magnetic resonance imaging (MRI), not only can the heat distribution within and around the tumor be measured during treatment, but also the extent of the lesion produced assessed. Interstitial laser thermotherapy (ILTT) performed under MRI monitoring, could become an important interdisciplinary minimally invasive treatment option for patients with brain tumors. Experimental data on the biological effects of interstitial laser therapy on normal brain tissue are not yet available, and only preliminary clinical studies investigating the effects of laser energy on brain tumors have so far been carried out. This overview presents a description of our own i...
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Papers by Alex Muacevic