SU-FF-T-394: An Image Guided Target Localization System for Brain Radiosurgery and Fractionated Stereotactic Radiotherapy Using a Non-Invasive Fixation

2005 ◽  
Vol 32 (6Part13) ◽  
pp. 2041-2042 ◽  
Author(s):  
J Jin ◽  
S Ryu ◽  
K Faber ◽  
B Movsas
Keyword(s):  
Stereotactic Radiotherapy ◽  
Target Localization ◽  
Fractionated Stereotactic Radiotherapy ◽  
Localization System ◽  
Non Invasive ◽  
Image Guided

INTRODUCING SITETRACK

Neurosurgery ◽  
2009 ◽  
Vol 64 (suppl_2) ◽  
pp. A110-A122 ◽  
Author(s):  
Kenichi Saito ◽  
Masami Fujii ◽  
Koji Kajiwara ◽  
Michiyasu Suzuki
Keyword(s):  
Regression Analysis ◽  
Stereotactic Radiotherapy ◽  
Head Movement ◽  
Target Localization ◽  
Mean Square ◽  
Localization System ◽  
System Parameters ◽  
Thermoplastic Mask ◽  
Emergency Stop ◽  
The Moment

Abstract OBJECTIVE Immobilization of the head during stereotactic radiotherapy (STR) has, until recently, been fundamental for ensuring accuracy. We developed a continuous motion monitoring system (SiteTrack) to detect and quantify head movement during CyberKnife (Accuray, Inc., Sunnyvale, CA) STR and Leksell (Elekta AB, Stockholm, Sweden) frame fixation. In this study, we present findings obtained during tests of SiteTrack. METHODS SiteTrack is composed of a potentiometer with 4 encoders connected through 4 threads tied to the plastic buttons attached to the thermoplastic mask, in the case of CyberKnife, or by 3 threads directly connected to the Leksell frame. The accuracy of SiteTrack was studied with a phantom using the target localization system of the CyberKnife. During CyberKnife treatment, SiteTrack software sends an emergency stop signal (E-stop) if the patient moves beyond a limit. Seventy-three cases of CyberKnife STR and 7 cases of Leksell frame fixation were monitored. RESULTS In the phantom study, regression analysis showed a significant correlation between SiteTrack and target localization system parameters. The expected root mean square position error at the moment of E-stop was 0.62 ± 0.44 mm when the E-stop limit was set at ±0.5 mm. Twenty-two (30%) of 73 patients kept still during CyberKnife treatment (<0.5 mm); 51 (70%) of 73 patients moved more than 0.5 mm and, thus, caused E-stops. SiteTrack monitoring during frame fixation showed motion beyond ±1 mm in 4 cases and ±0.5 mm in 3 other cases. CONCLUSION Significant head movement can occur during CyberKnife treatment or fixation with a Leksell frame. SiteTrack may improve the accuracy of the CyberKnife as well as frame-based STR.

Fractionated Stereotactic Radiotherapy For the Treatment of Large Arteriovenous Malformations with or without Previous Partial Embolization

Neurosurgery ◽  
2004 ◽  
Vol 55 (3) ◽  
pp. 519-531 ◽  
Author(s):  
Erol Veznedaroglu ◽  
David W. Andrews ◽  
Ronald P. Benitez ◽  
M. Beverly Downes ◽  
Maria Werner-Wasik ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Stereotactic Radiotherapy ◽  
Arteriovenous Malformations ◽  
Three Dimensional ◽  
Late Complications ◽  
Fractionated Stereotactic Radiotherapy ◽  
Medical Systems ◽  
Significant Treatment ◽  
Lost To Follow Up

Abstract OBJECTIVE: Despite the success of stereotactic radiosurgery, large inoperable arteriovenous malformations (AVMs) of 14 cm3 or more have remained largely refractory to stereotactic radiosurgery, with much lower obliteration rates. We review treatment of large AVMs either previously untreated or partially obliterated by embolization with fractionated stereotactic radiotherapy (FSR) regimens using a dedicated linear accelerator (LINAC). METHODS: Before treatment, all patients were discussed at a multidisciplinary radiosurgery board and found to be suitable for FSR. All patients were evaluated for pre-embolization. Those who had feeding pedicles amenable to glue embolization were treated. LINAC technique involved acquisition of a stereotactic angiogram in a relocatable frame that was also used for head localization during treatment. The FSR technique involved the use of six 7-Gy fractions delivered on alternate days over a 2-week period, and this was subsequently dropped to 5-Gy fractions after late complications in one of seven patients treated with 7-Gy fractions. Treatments were based exclusively on digitized biplanar stereotactic angiographic data. We used a Varian 600SR LINAC (Varian Medical Systems, Inc., Palo Alto, CA) and XKnife treatment planning software (Radionics, Inc., Burlington, MA). In most cases, one isocenter was used, and conformality was established by non-coplanar arc beam shaping and differential beam weighting. RESULTS: Thirty patients with large AVMs were treated between January 1995 and August 1998. Seven patients were treated with 42-Gy/7-Gy fractions, with one patient lost to follow-up and the remaining six with previous partial embolization. Twenty-three patients were treated with 30-Gy/5-Gy fractions, with two patients lost to follow-up and three who died as a result of unrelated causes. Of 18 evaluable patients, 8 had previous partial embolization. Mean AVM volumes at FSR treatment were 23.8 and 14.5 cm3, respectively, for the 42-Gy/7-Gy fraction and 30-Gy/5-Gy fraction groups. After embolization, 18 patients still had AVM niduses of 14 cm3 or more: 6 in the 7-Gy cohort and 12 in the 5-Gy cohort. For patients with at least 5-year follow-up, angiographically documented AVM obliteration rates were 83% for the 42-Gy/7-Gy fraction group, with a mean latency of 108 weeks (5 of 6 evaluable patients), and 22% for the 30-Gy/5-Gy fraction group, with an average latency of 191 weeks (4 of 18 evaluable patients) (P = 0.018). For AVMs that remained at 14 cm3 or more after embolization (5 of 6 patients), the obliteration rate remained 80% (4 of 5 patients) for the 7-Gy cohort and dropped to 9% for the 5-Gy cohort. A cumulative hazard plot revealed a 7.2-fold greater likelihood of obliteration with the 42-Gy/7-Gy fraction protocol (P = 0.0001), which increased to a 17-fold greater likelihood for postembolization AVMs of 14 cm3 or more (P = 0.003). CONCLUSION: FSR achieves obliteration for AVMs at a threshold dose, including large residual niduses after embolization. With significant treatment-related morbidities, further investigation warrants a need for better three-dimensional target definition with higher dose conformality.

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