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Arjun Sahgal - One of the best experts on this subject based on the ideXlab platform.
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Spinal Cord Dose Tolerance to Stereotactic Body Radiation Therapy.
International Journal of Radiation Oncology Biology Physics, 2019Co-Authors: Arjun Sahgal, Scott G Soltys, Lijun Ma, Wolfgang A. Tome, Joe H. Chang, Lawrence B. Marks, Michael T. Milano, Paul M. Medin, Andrzej Niemierko, C. Shun WongAbstract:Spinal cord tolerance data for stereotactic body radiation therapy (SBRT) were extracted from published reports, reviewed, and modelled. For de novo SBRT delivered in 1 to 5 fractions, the following spinal cord point maximum doses (Dmax) are estimated to be associated with a 1% to 5% risk of radiation myelopathy (RM): 12.4 to 14.0 Gy in 1 fraction, 17.0 Gy in 2 fractions, 20.3 Gy in 3 fractions, 23.0 Gy in 4 fractions, and 25.3 Gy in 5 fractions. For reirradiation SBRT delivered in 1 to 5 fractions, reported factors associated with a lower risk of RM include cumulative Thecal Sac equivalent dose in 2 Gy fractions with an alpha/beta of 2 (EQD22) Dmax ≤70 Gy; SBRT Thecal Sac EQD22 Dmax ≤25 Gy, Thecal Sac SBRT EQD22 Dmax to cumulative EQD22 Dmax ratio ≤0.5, and a minimum time interval to reirradiation of ≥5 months. Larger studies containing complete institutional cohorts with dosimetric data of patients treated with spine SBRT, with and without RM, are required to refine RM risk estimates.
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probabilities of radiation myelopathy specific to stereotactic body radiation therapy to guide safe practice
International Journal of Radiation Oncology Biology Physics, 2013Co-Authors: Samuel T Chao, Scott G Soltys, Eric L Chang, Alexander Muacevic, Alessandra Gorgulho, Arjun Sahgal, Vivian Weinberg, Peter C Gerszten, Lilyana AngelovAbstract:Purpose Dose-volume histogram (DVH) results for 9 cases of post spine stereotactic body radiation therapy (SBRT) radiation myelopathy (RM) are reported and compared with a cohort of 66 spine SBRT patients without RM. Methods and Materials DVH data were centrally analyzed according to the Thecal Sac point maximum (Pmax) volume, 0.1- to 1-cc volumes in increments of 0.1 cc, and to the 2 cc volume. 2-Gy biologically equivalent doses (nBED) were calculated using an α/β = 2 Gy (units = Gy 2/2 ). For the 2 cohorts, the nBED means and distributions were compared using the t test and Mann-Whitney test, respectively. Significance ( P Results Significant differences in both the means and distributions at the Pmax and up to the 0.8-cc volume were observed. Concordant significance was greatest for the Pmax volume. At the Pmax volume the fit of the logistic regression model, summarized by the area under the curve, was 0.87. A risk of RM of 5% or less was observed when limiting the Thecal Sac Pmax volume doses to 12.4 Gy in a single fraction, 17.0 Gy in 2 fractions, 20.3 Gy in 3 fractions, 23.0 Gy in 4 fractions, and 25.3 Gy in 5 fractions. Conclusion We report the first logistic regression model yielding estimates for the probability of human RM specific to SBRT.
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Reirradiation human spinal cord tolerance for stereotactic body radiotherapy.
International Journal of Radiation Oncology Biology Physics, 2010Co-Authors: Arjun Sahgal, Samuel T Chao, Lilyana Angelov, Eric L Chang, Vivian Weinberg, Lijun Ma, Iris C. Gibbs, Ung Kyu Chang, Maria Werner-wasik, Moon Jun SohnAbstract:Purpose We reviewed the treatment for patients with spine metastases who initially received conventional external beam radiation (EBRT) and were reirradiated with 1–5 fractions of stereotactic body radiotherapy (SBRT) who did or did not subsequently develop radiation myelopathy (RM). Methods and Materials Spinal cord dose–volume histograms (DVHs) for 5 RM patients (5 spinal segments) and 14 no-RM patients (16 spine segments) were based on Thecal Sac contours at retreatment. Dose to a point within the Thecal Sac that receives the maximum dose (P max ), and doses to 0.1-, 1.0-, and 2.0-cc volumes within the Thecal Sac were reviewed. The biologically effective doses (BED) using α/β = 2 Gy for late spinal cord toxicity were calculated and normalized to a 2-Gy equivalent dose (nBED = Gy 2/2 ). Results The initial conventional radiotherapy nBED ranged from ∼30 to 50 Gy 2/2 (median ∼40 Gy 2/2 ). The SBRT reirradiation Thecal Sac mean P max nBED in the no-RM group was 20.0 Gy 2/2 (95% confidence interval [CI], 10.8–29.2), which was significantly lower than the corresponding 67.4 Gy 2/2 (95% CI, 51.0–83.9) in the RM group. The mean total P max nBED in the no-RM group was 62.3 Gy 2/2 (95% CI, 50.3–74.3), which was significantly lower than the corresponding 105.8 Gy 2/2 (95% CI, 84.3–127.4) in the RM group. The fraction of the total P max nBED accounted for by the SBRT P max nBED for the RM patients ranged from 0.54 to 0.78 and that for the no-RM patients ranged from 0.04 to 0.53. Conclusions SBRT given at least 5 months after conventional palliative radiotherapy with a reirradiation Thecal Sac P max nBED of 20–25 Gy 2/2 appears to be safe provided the total P max nBED does not exceed approximately 70 Gy 2/2 , and the SBRT Thecal Sac P max nBED comprises no more than approximately 50% of the total nBED.
R E Collis - One of the best experts on this subject based on the ideXlab platform.
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shape of the Thecal Sac l3 4 interspace compared with l4 5
Anaesthesia, 2009Co-Authors: M Naji, M Williams, M D Hourihan, R E CollisAbstract:Summary We retrospectively reviewed 60 normal magnetic resonance imaging scans to assess the anatomical shape of the Thecal Sac at the L3/4 and L4/5 vertebral interspaces. In all cases the Thecal Sac was oval at L3/4 but in 26 (43%; 95% CI 31–55%) the Thecal Sac changed from oval at the L3/4 interspace to triangular at L4/5 (with the apex of the triangle presenting to the posterior epidural space). We propose that this anatomical variant would make it more difficult to obtain cerebrospinal fluid at the lower level, as a slightly lateral approach could lead to identification of the epidural space but failure to puncture the Thecal Sac. This may offer an explanation for a ‘dry tap’ when a lower interspace is chosen.
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Shape of the Thecal Sac: L3/4 interspace compared with L4/5.
Anaesthesia, 2008Co-Authors: M Naji, M Williams, M D Hourihan, R E CollisAbstract:Summary We retrospectively reviewed 60 normal magnetic resonance imaging scans to assess the anatomical shape of the Thecal Sac at the L3/4 and L4/5 vertebral interspaces. In all cases the Thecal Sac was oval at L3/4 but in 26 (43%; 95% CI 31–55%) the Thecal Sac changed from oval at the L3/4 interspace to triangular at L4/5 (with the apex of the triangle presenting to the posterior epidural space). We propose that this anatomical variant would make it more difficult to obtain cerebrospinal fluid at the lower level, as a slightly lateral approach could lead to identification of the epidural space but failure to puncture the Thecal Sac. This may offer an explanation for a ‘dry tap’ when a lower interspace is chosen.
Lilyana Angelov - One of the best experts on this subject based on the ideXlab platform.
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probabilities of radiation myelopathy specific to stereotactic body radiation therapy to guide safe practice
International Journal of Radiation Oncology Biology Physics, 2013Co-Authors: Samuel T Chao, Scott G Soltys, Eric L Chang, Alexander Muacevic, Alessandra Gorgulho, Arjun Sahgal, Vivian Weinberg, Peter C Gerszten, Lilyana AngelovAbstract:Purpose Dose-volume histogram (DVH) results for 9 cases of post spine stereotactic body radiation therapy (SBRT) radiation myelopathy (RM) are reported and compared with a cohort of 66 spine SBRT patients without RM. Methods and Materials DVH data were centrally analyzed according to the Thecal Sac point maximum (Pmax) volume, 0.1- to 1-cc volumes in increments of 0.1 cc, and to the 2 cc volume. 2-Gy biologically equivalent doses (nBED) were calculated using an α/β = 2 Gy (units = Gy 2/2 ). For the 2 cohorts, the nBED means and distributions were compared using the t test and Mann-Whitney test, respectively. Significance ( P Results Significant differences in both the means and distributions at the Pmax and up to the 0.8-cc volume were observed. Concordant significance was greatest for the Pmax volume. At the Pmax volume the fit of the logistic regression model, summarized by the area under the curve, was 0.87. A risk of RM of 5% or less was observed when limiting the Thecal Sac Pmax volume doses to 12.4 Gy in a single fraction, 17.0 Gy in 2 fractions, 20.3 Gy in 3 fractions, 23.0 Gy in 4 fractions, and 25.3 Gy in 5 fractions. Conclusion We report the first logistic regression model yielding estimates for the probability of human RM specific to SBRT.
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Reirradiation human spinal cord tolerance for stereotactic body radiotherapy.
International Journal of Radiation Oncology Biology Physics, 2010Co-Authors: Arjun Sahgal, Samuel T Chao, Lilyana Angelov, Eric L Chang, Vivian Weinberg, Lijun Ma, Iris C. Gibbs, Ung Kyu Chang, Maria Werner-wasik, Moon Jun SohnAbstract:Purpose We reviewed the treatment for patients with spine metastases who initially received conventional external beam radiation (EBRT) and were reirradiated with 1–5 fractions of stereotactic body radiotherapy (SBRT) who did or did not subsequently develop radiation myelopathy (RM). Methods and Materials Spinal cord dose–volume histograms (DVHs) for 5 RM patients (5 spinal segments) and 14 no-RM patients (16 spine segments) were based on Thecal Sac contours at retreatment. Dose to a point within the Thecal Sac that receives the maximum dose (P max ), and doses to 0.1-, 1.0-, and 2.0-cc volumes within the Thecal Sac were reviewed. The biologically effective doses (BED) using α/β = 2 Gy for late spinal cord toxicity were calculated and normalized to a 2-Gy equivalent dose (nBED = Gy 2/2 ). Results The initial conventional radiotherapy nBED ranged from ∼30 to 50 Gy 2/2 (median ∼40 Gy 2/2 ). The SBRT reirradiation Thecal Sac mean P max nBED in the no-RM group was 20.0 Gy 2/2 (95% confidence interval [CI], 10.8–29.2), which was significantly lower than the corresponding 67.4 Gy 2/2 (95% CI, 51.0–83.9) in the RM group. The mean total P max nBED in the no-RM group was 62.3 Gy 2/2 (95% CI, 50.3–74.3), which was significantly lower than the corresponding 105.8 Gy 2/2 (95% CI, 84.3–127.4) in the RM group. The fraction of the total P max nBED accounted for by the SBRT P max nBED for the RM patients ranged from 0.54 to 0.78 and that for the no-RM patients ranged from 0.04 to 0.53. Conclusions SBRT given at least 5 months after conventional palliative radiotherapy with a reirradiation Thecal Sac P max nBED of 20–25 Gy 2/2 appears to be safe provided the total P max nBED does not exceed approximately 70 Gy 2/2 , and the SBRT Thecal Sac P max nBED comprises no more than approximately 50% of the total nBED.
John H Chi - One of the best experts on this subject based on the ideXlab platform.
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glioproliferative lesion of the spinal cord as a complication of stem cell tourism
The New England Journal of Medicine, 2016Co-Authors: Aaron L Berkowitz, Michael B Miller, Saad A Mir, Daniel N Cagney, Vamsidhar Chavakula, Indira Guleria, Ayal A Aizer, Keith L Ligon, John H ChiAbstract:A primitive neoplasm composed predominantly of nonhost cells was detected in the thoracic spinal cord and Thecal Sac of a 66-year-old man who had received experimental stem-cell treatment from commercial clinics.
A Sayah - One of the best experts on this subject based on the ideXlab platform.
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3d t2 mr imaging based measurements of the posterior cervical Thecal Sac in flexion and extension for cervical puncture
American Journal of Neuroradiology, 2016Co-Authors: M P Bazylewicz, F Berkowitz, A SayahAbstract:BACKGROUND AND PURPOSE: The current standard technique for cervical puncture involves prone positioning with neck extension. The purpose of this study was to compare measurements of the posterior cervical Thecal Sac during neck flexion and extension in supine and prone positions by using high-resolution MR imaging to help determine the optimal positioning for cervical puncture. MATERIALS AND METHODS: High-resolution T2-weighted MR imaging was performed of the cervical spine in 10 adult volunteers 18 years of age and older. Exclusion criteria included the following: a history of cervical spine injury/surgery, neck pain, and degenerative spondylosis. Images of sagittal 3D sampling perfection with application-optimized contrasts by using different flip angle evolutions were obtained in the following neck positions: supine extension, supine flexion, prone extension, and prone flexion. The degree of neck flexion and extension and the distance from the posterior margin of the spinal cord to the posterior aspect of the C1–C2 Thecal Sac were measured in each position. RESULTS: The mean anteroposterior size of the posterior C1–C2 Thecal Sac was as follows: 4.76 mm for supine extension, 3.63 mm for supine flexion, 5.00 mm for prone extension, and 4.00 mm for prone flexion. Neck extension yielded a larger CSF space than flexion, independent of supine/prone positioning. There was no correlation with neck angle and Thecal Sac size. CONCLUSIONS: The posterior C1–C2 Thecal Sac is larger with neck extension than flexion, independent of prone or supine positioning. Given that this space is the target for cervical puncture, findings suggest that extension is the ideal position for performing the procedure, and the decision for prone-versus-supine positioning can be made on the basis of operator comfort and patient preference/ability.
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3D T2 MR Imaging–Based Measurements of the Posterior Cervical Thecal Sac in Flexion and Extension for Cervical Puncture
American Journal of Neuroradiology, 2015Co-Authors: M P Bazylewicz, F Berkowitz, A SayahAbstract:BACKGROUND AND PURPOSE: The current standard technique for cervical puncture involves prone positioning with neck extension. The purpose of this study was to compare measurements of the posterior cervical Thecal Sac during neck flexion and extension in supine and prone positions by using high-resolution MR imaging to help determine the optimal positioning for cervical puncture. MATERIALS AND METHODS: High-resolution T2-weighted MR imaging was performed of the cervical spine in 10 adult volunteers 18 years of age and older. Exclusion criteria included the following: a history of cervical spine injury/surgery, neck pain, and degenerative spondylosis. Images of sagittal 3D sampling perfection with application-optimized contrasts by using different flip angle evolutions were obtained in the following neck positions: supine extension, supine flexion, prone extension, and prone flexion. The degree of neck flexion and extension and the distance from the posterior margin of the spinal cord to the posterior aspect of the C1–C2 Thecal Sac were measured in each position. RESULTS: The mean anteroposterior size of the posterior C1–C2 Thecal Sac was as follows: 4.76 mm for supine extension, 3.63 mm for supine flexion, 5.00 mm for prone extension, and 4.00 mm for prone flexion. Neck extension yielded a larger CSF space than flexion, independent of supine/prone positioning. There was no correlation with neck angle and Thecal Sac size. CONCLUSIONS: The posterior C1–C2 Thecal Sac is larger with neck extension than flexion, independent of prone or supine positioning. Given that this space is the target for cervical puncture, findings suggest that extension is the ideal position for performing the procedure, and the decision for prone-versus-supine positioning can be made on the basis of operator comfort and patient preference/ability.
