Initial clinical experience with frameless radiosurgery for patients with intracranial metastases
ABSTRACT To review the initial clinical experience with frameless stereotactic radiosurgery (SRS) for treating intracranial metastatic disease.
Sixty-four patients received frameless SRS for intracranial metastatic disease. Minimum follow-up was 6 months with none lost to follow-up. Patients had a median of 2 metastases and a maximum of 4. The median number of isocenters was 2 with median arcs of 10 and median dose of 17.5 Gy. Thirteen patients were treated for progressive/recurrent disease after surgical resection or whole brain radiotherapy (WBRT). Fifty-one patients were treated with frameless SRS as an an adjunct to initial treatment. Of the total treated, 17 were treated with SRS alone, 20 were treated with WBRT plus SRS, 16 were treated with surgical resection plus SRS, and the remaining 11 were treated with surgical resection plus WBRT plus SRS.
With a median actuarial follow-up period of 8.2 months, ultimate local control was 88%. The median time to progression was 8.1 months. The median overall survival was 8.7 months. Of the 17 patients treated with SRS alone, 86% had ultimate local control with mean overall survival of 7.1 months. Of the 13 patients who received surgical resection plus SRS without WBRT as primary treatment, there was 85% ultimate local control with an overall survival of 10.3 months. Three patients treated with initial surgery alone had recurrence treated with SRS 2-3 months after resection. All these patients obtained local control and median survival was >10 months. Of the 13 patients who received WBRT followed by SRS as boost treatment, 92% had local control and mean overall survival was 7.3 months. Of 7 patients who received SRS after recurrence after WBRT, 100% had local control with median survival of 8.2 months. For 8 patients who received surgery followed by WBRT and SRS, local control was 50%; however, ultimate intracranial control was achieved in 7 of 8 patients with repeat SRS and surgical resection. The overall survival in this group of patients was 14.7 months. No patient had a serious (Grade 3 or higher) complication requiring intervention.
Frameless optically guided radiosurgery is less invasive, can be performed as a standard radiotherapy-based simulation procedure, and maintains submillimetric accuracy. Our initial results with frameless SRS for metastatic disease suggest survival times and local control (88%) eqiuvalent to frame-based methodologies. Practical noninvasive delivery makes treatment and potential retreatment to avoid WBRT more feasible.
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ABSTRACT: The range of patient setup errors in six dimensions detected in clinical routine for cranial as well as for extracranial treatments, were analyzed while performing linear accelerator based stereotactic treatments with frameless patient setup systems. Additionally, the need for re-verification of the patient setup for situations where couch rotations are involved was analyzed for patients treated in the cranial region. A total of 2185 initial (i.e. after pre-positioning the patient with the infrared system but before image guidance) patient setup errors (1705 in the cranial and 480 in the extracranial region) obtained by using ExacTrac (BrainLAB AG, Feldkirchen, Germany) were analyzed. Additionally, the patient setup errors as a function of the couch rotation angle were obtained by analyzing 242 setup errors in the cranial region. Before the couch was rotated, the patient setup error was corrected at couch rotation angle 0° with the aid of image guidance and the six degrees of freedom (6DoF) couch. For both situations attainment rates for two different tolerances (tolerance A: ±0.5mm, ±0.5°; tolerance B: ±1.0mm, ±1.0°) were calculated. The mean (± one standard deviation) initial patient setup errors for the cranial cases were -0.24±1.21°, -0.23±0.91° and -0.03±1.07° for the pitch, roll and couch rotation axes and 0.10±1.17mm, 0.10±1.62mm and 0.11±1.29mm for the lateral, longitudinal and vertical axes, respectively. Attainment rate (all six axes simultaneously) for tolerance A was 0.6% and 13.1% for tolerance B, respectively. For the extracranial cases the corresponding values were -0.21±0.95°, -0.05±1.08° and -0.14±1.02° for the pitch, roll and couch rotation axes and 0.15±1.77mm, 0.62±1.94mm and -0.40±2.15mm for the lateral, longitudinal and vertical axes. Attainment rate (all six axes simultaneously) for tolerance A was 0.0% and 3.1% for tolerance B, respectively. After initial setup correction and rotation of the couch to treatment position a re-correction has to be performed in 77.4% of all cases to fulfill tolerance A and in 15.6% of all cases to fulfill tolerance B. The analysis of the data shows that all six axes of a 6DoF couch are used extensively for patient setup in clinical routine. In order to fulfill high patient setup accuracies (e.g. for stereotactic treatments), a 6DoF couch is recommended. Moreover, re-verification of the patient setup after rotating the couch is required in clinical routine.Zeitschrift für Medizinische Physik 01/2014; 24(2). DOI:10.1016/j.zemedi.2013.11.002 · 1.81 Impact Factor
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ABSTRACT: Recurrent malignant primary and metastatic central nervous system (CNS) tumors in pediatric patients are devastating, and efforts to improve outcomes for these patients have been disappointing. Conventional re-irradiation in these patients increases the risk of significant toxicity. We therefore evaluated feasibility and outcomes using frameless radiosurgery (FRS) in children with recurrent primary and metastatic brain tumors. We reviewed five cases of recurrent primary and metastatic brain tumors treated with frameless radiosurgery between 2008 and 2013. We analyzed safety and feasibility, dosimetric data, local control, and adverse effects. Five patients were treated with frameless radiosurgery for palliation. Fifteen target volumes were treated using our institutional FRS system. The volumes of targets ranged from 0.08 to 51.67 cm(3) with doses ranging from 15 to 21 Gy. Radiosurgery was well tolerated, decreased the need for large-volume CNS irradiation, and allowed for effective palliation in this small cohort. Frameless radiosurgery is feasible in this patient population. Frameless radiosurgery should be considered in management of select patients with recurrent primary or metastatic brain tumors.Journal of Neuro-Oncology 02/2014; 117(2). DOI:10.1007/s11060-014-1392-7 · 3.12 Impact Factor
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ABSTRACT: Purpose: The spatial and temporal tracking performance of a commercially available 3D optical surface imaging system is evaluated for its potential use in frameless stereotactic radiosurgery head tracking applications.Methods: Both 3D surface and infrared (IR) marker tracking were performed simultaneously on a head phantom mounted on an xyz motion stage and on four human subjects. To allow spatial and temporal comparison on human subjects, three points were simultaneously monitored, including the upper facial region (3D surface), a dental plate (IR markers), and upper forehead (IR markers).Results: For both static and dynamic phantom studies, the 3D surface tracker was found to have a root mean squared error (RMSE) of approximately 0.30 mm for region-of-interest (ROI) surface sizes greater than 1000 vertex points. Although, the processing period (1∕fps) of the 3D surface system was found to linearly increase as a function of the number of ROI vertex points, the tracking accuracy was found to be independent of ROI size provided that the ROI was sufficiently large and contained features for registration. For human subjects, the RMSE between 3D surface tracking and IR marker tracking modalities was 0.22 mm left-right (x-axis), 0.44 mm superior-inferior (y-axis), 0.27 mm anterior-posterior (z-axis), 0.29° pitch (around x-axis), 0.18° roll (around y-axis), and 0.15° yaw (around z-axis).Conclusions: 3D surface imaging has the potential to provide submillimeter level head motion tracking. This is provided that a highly accurate camera-to-LINAC frame of reference calibration can be performed and that the reference ROI is of sufficient size and contains suitable surface features for registration.Medical Physics 11/2013; 40(11):111712. DOI:10.1118/1.4823757 · 3.01 Impact Factor