Three-Dimensional Dosimetry for Complex Stereotactic Radiosurgery Using a Tomographic Optical Density Scanner and BANGTMPolymer Gels

1997 ◽  
pp. 251-260
Author(s):  
J.P.S. Knisely ◽  
L. Liu ◽  
M.J. Maryanski ◽  
M. Ranade ◽  
R.J. Schulz ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Optical Density ◽  
Three Dimensional ◽  
Polymer Gels

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.

SU-GG-T-308: Polymer Cross-Linking and Sensitivity Enhancement in Normoxic Polymer Gels Used for Three-Dimensional Dosimetry

2008 ◽  
Vol 35 (6Part14) ◽  
pp. 2796-2796
Author(s):  
R Martin ◽  
J BenComo ◽  
M Heard ◽  
M Martin ◽  
K Kaluarachchi ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Polymer Gels ◽  
Sensitivity Enhancement ◽  
Cross Linking

Development of a Stereotactic Radiosurgery Frame Adapter for a Multichannel MRI Coil

2020 ◽  
pp. 1-8
Author(s):  
Byungmok Kim ◽  
Yongmin Chang ◽  
Hea Jung Choi ◽  
Ki-Su Park ◽  
Ji-ung Yang ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Single Channel ◽  
Signal To Noise Ratio ◽  
Brain Mri ◽  
Three Dimensional ◽  
Mr Images ◽  
Geometrical Accuracy ◽  
Channel Coil ◽  
T1 And T2 ◽  
Mri Coils

<b><i>Background:</i></b> The usage of multichannel brain MRI coils, which have several advantages over single-channel brain coils used for stereotactic radiosurgery (SRS), requires a frame adapter device to fit the frames inside the multichannel brain coils. However, such a frame adapter has not been developed until now. <b><i>Objective:</i></b> to develop an SRS frame adapter for multichannel MRI coils and verify the geometrical accuracy and signal-to-noise ratio (SNR) of the MR images obtained using multichannel MRI coils. <b><i>Methods:</i></b> We fabricated an SRS frame adapter for a 48-channel MRI coil using a three-dimensional (3D) printer. Furthermore, we obtained phantom and human-brain MR images with a 3.0 Tesla MRI scanner using multi- and single-channel coils. Computed tomography (CT) phantom images were also obtained as reference. We compared the coordinate errors of the multi- and single-channel coils to evaluate the geometrical accuracy. Two neurosurgeons measured the coordinates. In addition, we compared the SNR differences between multi- and single-channel coils using the T1- and T2-weighted brain images. <b><i>Results:</i></b> For the CT coordinate measurements, the correlation coefficient <i>r</i> = 1 and <i>p</i> &#x3c; 0.001 with respect to the 3 axes (Δ<i>x</i>, Δ<i>y</i>, and Δ<i>z</i>) and 3D errors (Δ<i>r</i>) showed no interpersonal differences between the 2 neurosurgeons. The results obtained using the T1-weighted images showed that a multichannel coil had smaller coordinate errors in Δ<i>x</i>, Δ<i>y</i>, Δ<i>z</i>, and Δ<i>r</i> than that observed in case of a single-channel coil (<i>p</i> &#x3c; 0.001). In case of the SNR measurements, most of the brain areas showed higher SNRs when using a multichannel coil compared with that observed when using a single-channel coil in the T1- and T2-weighted images. <b><i>Conclusion:</i></b> Compared with single-channel coils, the use of multichannel MRI coils with a newly developed frame adapter is expected to ensure successful SRS treatments with improved geometrical accuracy and SNR.

scholarly journals Stereotactic Radiosurgery Associated Neurotoxicity

2003 ◽  
Vol 2 (2) ◽  
pp. 147-151 ◽  
Author(s):  
William H. St. Clair ◽  
Curtis A. Given
Keyword(s):  
Stereotactic Radiosurgery ◽  
Therapeutic Option ◽  
Treatment Plan ◽  
Three Dimensional ◽  
Reference Points ◽  
Therapeutic Modality ◽  
High Dose ◽  
Lesion Volume ◽  
Three Dimensional Mapping ◽  
Effective Therapeutic Option

Stereotactic radiosurgery (SRS) is an evolving therapeutic modality for well demarcated intracranial lesions. Since the inception of stereotactic radiosurgery the types of parenchymal CNS lesions addressed by this mode of treatment has increased. All modern stereotactic radiosurgical procedures employ several common features. Patients are fitted with a stereotactic head frame or fiducial markers followed by radiographic imaging which allows for external reference points and three-dimensional mapping of the intracranial lesion. Armed with this information a highly conformal treatment plan is developed to deliver a high dose of radiation to a sharply defined target, with rapid dose fall-off outside the lesion volume. While an extremely effective therapeutic option, SRS is not without risk of neurotoxicity, with radiation necrosis being the most commonly recognized complication. The neurotoxic effects of SRS are reviewed and discussed.

Three-dimensional Fast Imaging Employing Steady-state Acquisition Magnetic Resonance Imaging for Stereotactic Radiosurgery of Trigeminal Neuralgia

Neurosurgery ◽  
2005 ◽  
Vol 56 (3) ◽  
pp. E628-E628 ◽  
Author(s):  
Gabriela-del-Rocío Chávez Chávez ◽  
Antonio A.F. De Salles ◽  
Timothy D. Solberg ◽  
Alessandra Pedroso ◽  
Dulce Espinoza ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Steady State ◽  
Magnetic Resonance ◽  
Trigeminal Neuralgia ◽  
Stereotactic Radiosurgery ◽  
Trigeminal Nerve ◽  
Three Dimensional ◽  
Fast Imaging ◽  
Resonance Imaging ◽  
Entry Zone

Abstract OBJECTIVE: The aim of this study was to demonstrate the use and applications of the three-dimensional fast imaging employing steady-state acquisition (3-D-FIESTA) magnetic resonance imaging sequence in targeting and planning for stereotactic radiosurgery of trigeminal neuralgia. METHODS: A 3-D-FIESTA sequence for visualization of cranial nerves in the cranial base was added to the routine magnetic resonance imaging scan to enhance the treatment planning for trigeminal neuralgia. T1-weighted images, 1 mm thick, were directly compared with the FIESTA sequence for the exact visualization of the trigeminal entry zone and surrounding vasculature. The target accuracy was evaluated by image fusion of computed tomographic and magnetic resonance imaging scans. The anatomy visualized with the FIESTA sequence was validated by direct inspection of the gross anatomic specimens of the trigeminal complex. RESULTS: A total of 15 consecutive patients, 10 women and 5 men, underwent radiosurgery for essential trigeminal neuralgia between April and July, 2003. The mean age of the patients was 65.2 years (range, 24–83 yr). Nine patients had right-sided symptoms. Four patients had had previous surgery (two microvascular decompression, one percutaneous rhizotomy, and one radiofrequency thermocoagulation). The 3-D-FIESTA sequence successfully demonstrated the trigeminal complex (root entry zone, trigeminal ganglion, rootlets, and vasculature) in 14 patients (93.33%). The 3-D-FIESTA sequence also allowed visualization of the branches of the trigeminal nerve inside Meckel's cavity. This exact visualization correlated precisely with the anatomic specimens. In one patient (6.66%), it was not possible to demonstrate the related vasculature. However, the other structures were clearly visualized. CONCLUSION: The 3-D-FIESTA sequence is used in this study for demonstration of the exact anatomy of the trigeminal complex for the purpose of radiosurgical planning and treatment of trigeminal neuralgia. With such imaging techniques, radiosurgical targeting of specific trigeminal nerve branches may be feasible. It has not been possible previously to target individual branches of the trigeminal nerve.

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