Spinal Radiosurgery Research Articles

Comparison of Dose Distribution in Spine Radiosurgery Plans: Simultaneously Integrated Boost and RTOG 0631 Protocol

176 This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF-2012R1A1A2042414). This study was supported by Samsung Medical Center Grant [GFO1130081] and this study was supported by a grant of the Korea Healthcare Technology R&D Project, Ministry of Health and Welfare, Republic of Korea (HI10C2020). Received 18 August 2014, Revised 17 September 2014, Accepted 18 September 2014 Correspondence: Dongryul Oh (dongryul.oh@samsung.com) Tel: 82-2-3410-2613, Fax: 82-2-3410-2619 cc This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Comparison of Dose Distribution in Spine Radiosurgery Plans: Simultaneously Integrated Boost and RTOG 0631 Protocol

Incidence and Risk Factors for Pain Flare Following Spine Radiosurgery

Incidence and Risk Factors for Pain Flare Following Spine Radiosurgery

The Role of Spine Radiosurgery in the Management Paradigm of Spine Metastases

The Role of Spine Radiosurgery in the Management Paradigm of Spine Metastases

Radiosurgery as Primary Treatment for Vertebral Metastases: Results From an International Multicenter Database

was: Improved or stable 91% and progressive 9%. A dose-response analysis showed that a prescribed dose of EQD2/10 > 33 Gy significantly (p Z 0.003) correlated with pain control as was the cumulative dose of the SRS and EBRT (EQD2/10 > 67; p Z 0.001). Other factors influencing pain response included controlled systemic disease, interval between EBRT and SRS > 12 months, single fraction radiosurgery and a Bilsky score of 0 to 1b. Neurologic deficits were improved or stable in 91% of patients. The ASIA status at the last clinical follow-up was E-78%, D-16%, C-3%, and B-1%. A new vertebral fracture was observed in 2.4% of the SRS courses and progressive spinal fractures were seen in 4.1%. There were no cases of radiation induced myelopathy. Conclusions: Stereotactic spinal radiosurgery following EBRT offers highly promising pain control. Durable local control and neurologic stabilization can be achieved in a retreatment population. With proper treatment planning and delivery, re-irradiation can be safely utilized and offers significant benefits in this patient population. Author Disclosure: C. Kersh: None. J. Sheehan: None. P. Gerszten: None. J. Flickenger: None. A. Sahgal: None. D. Letourneau: None. I. Grills: None. M. Jawad: None. F. Mantel: None. M. Guckenberger: None.

The clinical effect of Body-Fix device in improving the positioning accuracy of the hypofractionated radiotherapy in the vertebral metastatic patients

Objective To study the immobilization effect and keep the accurate treating position of Body-Fix device in the patients with vertebral metastatic tumor treated by hypofractionated intensity- modulated radiotherapy. Methods From October 2008 to February 2010, six nasopharyngeal carcinoma patients with 10 treated lesion with vertebral metastasis who were treated by hypofractionated intensity- modulated radiotherapy and immobilized by the Body-Fix device were enrolled in this study. Three sets cone beam CT images were taken and recorded when patient was underway the initial setup, position correction and after radiation delivery. Comparing these images with the planning CT images to get the setup errors and the intrafractional position shifting, and the immobilization effect of Body-Fix device was analyzed. Results In the upper, middle and lower sections of the vertebrae, the intrafractional setup errors in the left-right direction were （ - 0. 6 ± 0. 5 ） ram, （ - 0. 1 ± 1.0 ） mm, （0.0 ± 0.4 ） mm, with in the superior-inferior direction （ 1.0 ± 1.4） mm, （4.8 ± 5.7 ） mm, （0.0 ± 0. 3 ） mm and in the anterior-posterior direction （ 1.2 ± 5.2 ） mm, （ - 0. 3 ± 0. 3 ） mm, （ 0.0 ± 0. 5 ） mm, respectively. Conclusions With Body-Fix device, the intrafractional setup errors can be minimized within 2 mm which make the accurate spinal radiosurgery technique possible. Key words: Body-Fix device; Set-up error; Vertebral metastasis neoplasms/intensity- modulated radiotherapy

A multi-national report on methods for institutional credentialing for spine radiosurgery

BackgroundStereotactic body radiotherapy and radiosurgery are rapidly emerging treatment options for both malignant and benign spine tumors. Proper institutional credentialing by physicians and medical physicists as well as other personnel is important for the safe and effective adoption of spine radiosurgery. This article describes the methods for institutional credentialing for spine radiosurgery at seven highly experienced international institutions.MethodsAll institutions (n = 7) are members of the Elekta Spine Radiosurgery Research Consortium and have a dedicated research and clinical focus on image-guided spine radiosurgery. A questionnaire consisting of 24 items covering various aspects of institutional credentialing for spine radiosurgery was completed by all seven institutions.ResultsClose agreement was observed in most aspects of spine radiosurgery credentialing at each institution. A formal credentialing process was believed to be important for the implementation of a new spine radiosurgery program, for patient safety and clinical outcomes. One institution has a written policy specific for spine radiosurgery credentialing, but all have an undocumented credentialing system in place. All institutions rely upon an in-house proctoring system for the training of both physicians and medical physicists. Four institutions require physicians and medical physicists to attend corporate sponsored training. Two of these 4 institutions also require attendance at a non-corporate sponsored academic society radiosurgery course. Corporate as well as non-corporate sponsored training were believed to be complimentary and both important for training. In 5 centers, all cases must be reviewed at a multidisciplinary conference prior to radiosurgery treatment. At 3 centers, neurosurgeons are not required to be involved in all cases if there is no evidence for instability or spinal cord compression. Backup physicians and physicists are required at only 1 institution, but all institutions have more than one specialist trained to perform spine radiosurgery. All centers believed that credentialing should also be device specific, and all believed that professional societies should formulate guidelines for institutions on the requirements for spine radiosurgery credentialing. Finally, in 4 institutions radiation therapists were required to attend corporate-sponsored device specific training for credentialing, and in only 1 institution were radiation therapists required to also attend academic society training for credentialing.ConclusionsThis study represents the first multi-national report of the current practice of institutional credentialing for spine radiosurgery. Key methodologies for safe implementation and credentialing of spine radiosurgery have been identified. There is strong agreement among experienced centers that credentialing is an important component of the safe and effective implementation of a spine radiosurgery program.

RTOG 0631 phase 2/3 study of image guided stereotactic radiosurgery for localized (1-3) spine metastases: Phase 2 results

PurposeThe phase 2 component of Radiation Therapy Oncology Group (RTOG) 0631 assessed the feasibility and safety of spine radiosurgery (SRS) for localized spine metastases in a cooperative group setting. Methods and MaterialsPatients with 1-3 spine metastasis with a Numerical Rating Pain Scale (NRPS) score ≥5 received 16 Gy single fraction SRS. The primary endpoint was SRS feasibility: image guidance radiation therapy (IGRT) targeting accuracy ≤2 mm, target volume coverage >90% of prescription dose, maintaining spinal cord dose constraints (10 Gy to ≤10% of the cord volume from 5-6 mm above to 5-6 mm below the target or absolute spinal cord volume <0.35 cc) and other normal tissue dose constraints. A feasibility success rate <70% was considered unacceptable for continuation of the phase 3 component. Based on the 1-sample exact binomial test with α = 0.10 (1-sided), 41 patients were required. Acute toxicity was assessed using the National Cancer Institute Common Toxicity Criteria for Adverse Events, version 3.0. ResultsSixty-five institutions were credentialed with spine phantom dosimetry and IGRT compliance. Forty-six patients were accrued, and 44 were eligible. There were 4 cervical, 21 thoracic, and 19 lumbar sites. Median NRPS was 7 at presentation. Final pretreatment rapid review was approved in 100%. Accuracy of image guided SRS targeting was in compliance with the protocol in 95%. The target coverage and spinal cord dose constraint were in accordance with the protocol requirements in 100% and 97%. Overall compliance for other normal tissue constraints was per protocol in 74%. There were no cases of grade 4-5 acute treatment-related toxicity. ConclusionsThe phase 2 results demonstrate the feasibility and accurate use of SRS to treat spinal metastases, with rigorous quality control, in a cooperative group setting. The planned RTOG 0631 phase 3 component will proceed to compare pain relief and quality of life between SRS and external beam radiation therapy.

SU‐E‐T‐677: The Effects of Respiratory Motion in RapidArc Spinal Stereotactic Radiosurgery

Purpose: Spinal radiosurgery is planned to strict tolerances. Unaccounted for dosimetric changes resulting from respiratory motion might lead to delivery of a sub‐optimal plan. We examine these effects for RapidArc spine radiosurgery. Methods: Plans were created for three patients that received 4D‐CT scans in a spinal radiosurgery set‐up. A target covering a single vertebral body and pedicles was defined and the spinal canal was contoured for each patient. Plans that delivered 18 Gy to the targets were created on the free breathing scans (FB). The maximum inspiration and expiration 4D‐CT phases were fused to the FB based on target and spinal canal position. The FB plans were copied onto these images and doses were calculated. Point doses, DVHs, and plan subtractions were used to evaluate plan differences. Motion was measured at fixed points on the 4D‐CTs. Results: The target for case 1 was defined at T4, case two at T7, and case three at T9. For all cases the target and the spinal canal moved &lt; 1 mm, while the skin surface moved 1–2.5 mm. For the T4 plan the aortic arch moved about 6 mm. For the T7 and T9 cases the diaphragm moved 5 mm and 12.3 mm, respectively. Point dose changes in the targets between the maximum inspiration and exhalation plans were 8.1 cGy, 69.0 cGy, and 58.1 cGy for the T4, T7, and T9 plans. Point changes in the spinal canal were 13.8 cGy, 34.0 cGy, and 34.1 cGy for the T4, T7, and T9 plans. Spinal canal DVHs changes were negligible in all cases. Changes in target coverage at doses &gt;= 18 Gy were approximately 5% for the T7 and T9 plans. Conclusion: Respiratory motion may alter the dosimetry of spinal radiosurgery plans. The clinical impact of these changes appears to be small.

Stereotactic radiosurgery for spinal metastases: a literature review

ABSTRACTObjective:The spine is the most common location for bone metastases. Since cure is not possible, local control and relief of symptoms is the basis for treatment, which is grounded on the use of conventional radiotherapy. Recently, spinal radiosurgery has been proposed for the local control of spinal metastases, whether as primary or salvage treatment. Consequently, we carried out a literature review in order to analyze the indications, efficacy, and safety of radiosurgery in the treatment of spinal metastases.Methods:We have reviewed the literature using the PubMed gateway with data from the MEDLINE library on studies related to the use of radiosurgery in treatment of bone metastases in spine. The studies were reviewed by all the authors and classified as to level of evidence, using the criterion defined by Wright.Results:The indications found for radiosurgery were primary control of epidural metastases (evidence level II), myeloma (level III), and metastases known to be poor responders to conventional radiotherapy – melanoma and renal cell carcinoma (level III). Spinal radiosurgery was also proposed for salvage treatment after conventional radiotherapy (level II). There is also some evidence as to the safety and efficacy of radiosurgery in cases of extramedullar and intramedullar intradural metastatic tumors (level III) and after spinal decompression and stabilization surgery.Conclusion:Radiosurgery can be used in primary or salvage treatment of spinal metastases, improving local disease control and patient symptoms. It should also be considered as initial treatment for radioresistant tumors, such as melanoma and renal cell carcinoma.

SU‐E‐T‐162: Prospective Treatment Plan Modeling To Guide Patient‐Specific Treatment Setups for Hypofractionated Intracranial and Spinal Radiosurgery

Purpose: Residual patient setup shifts such as 1 mm or 1 degree are commonly observed during online treatment setups of hypofractionated radiosurgery (HRS) of spine and intracranial lesions. To effectively guide patient‐specific setups, a prospective treatment planning approach was developed for such treatments. Methods: For a cohort of intracranial and spinal HRS treatments, individualized setup guidelines were prospectively determined via the following approach: (1) systematically shift and rotate 3D patient image data in incremental small steps. (2) For each step such as 0.1 mm or 0.1 degree, dose distributions from original treatment plan were recalculated. (3) Each resulting dose distributions were then iteratively checked against a set of preset dosimetric criteria for compliance. (4) From step 3, maximum tolerable shift levels along the major axes were then determined. Finally, we tested such an approached on a cohort of treatment cases performed at our institutions. Results: For studied treatment sessions (n=63), the mean maximum tolerable shift levels including rotations projected unto the major axes were determined to be 2.0±0.7mm, 2.1±0.9 mm and 1.9±0.8 mm along the lateral, longitudinal, and vertical axis, respectively. Such tolerance levels were significantly (p=0.02) larger than the machine preset tolerance level of 1.0 mm that commonly enforced for all treatment sessions. However, more than 50% of the treatment sessions exhibited sub‐millimeter tolerance level along certain directions to meet critical structure constraints. For example, a 0.6‐mm anterior maximum shift could incur 36% increase in the maximum dose to the brainstem for one patient case. Conclusion: Patient specific online setup guidelines for HRS has been demonstrated to prevent potential deleterious effects from residual shifts while facilitating online setups by providing more room of larger acceptable shifts for a majority of treatment cases.

MO‐F‐108‐05: Treatment Planning Study of Volumetric Arc Therapy for Spine Stereotactic Radiosurgery Using Flattening Filter Free Beams

Purpose: To evaluate the potential usage of flattening filter‐free (FFF) with volumetric modulated arc therapy (VMAT) in the treatment of spine radiosurgery. Methods: VMAT plans were retrospectively generated for six patients treated with intensity modulated radiotherapy (IMRT) according to the RTOG 0631 protocol. The VMAT plans were developed in the Eclipse treatment planning system on a Varian Truebeam equipped with a Millennium 120 MLC system, using the flattening‐filter‐free mode with a maximum dose rate of 1400 MU/min. The plans were prescribed to either 16 or 18Gy in one fraction to cover at least 90% of the target. Planning target volume (PTV) coverage, conformity index (CI), dose to spinal cord, distance to fall off between the prescription and maximum isodose line of the cord, as well as plan delivery efficiency were evaluated. Results: PTV coverage was better for VMAT compared to IMRT plans. The ratios between VMAT and IMRT for PTV coverage were 1.06 for D99% and 1.01 for D95%. The hot spots were comparable; the ratios of D10% and D5% were both 0.994. The VMAT plans were more conformal than the IMRT plans (CI of 1.13 vs. 1.28, p= 0. 0004). The VMAT plans also had shorter distance to fall off between the prescription and max cord isodose line (0.28 vs. 0.38 cm, p=0.0006). The average cord dose is 4.72 Gy in the VMAT plans, relative to 5.77 Gy in the IMRT plans. Finally, the VMAT treatments required slightly less MUs than the IMRT plans (8236 vs 9410, p=0.116). Conclusion: The VMAT plans had better PTV coverage compared to the IMRT plans. Furthermore, VMAT allowed for lower mean dose to the spinal cord, a sharper dose gradient between the PTV and the cord, and required fewer MUs, thus reducing the treatment time.

Evaluation of Real-time Target Positioning Accuracy in Spinal Radiosurgery

Stereotactic Radiosurgery require high accuracy and precision of patient positioning and target localization. We evaluate the real time positioning accuracy of isocenter using optic guided patient positioning system, ExacTrac (BrainLab, Germany), during spinal radiosurgery procedure. The system is based on real time detect multiple body markers attached on the selected patient skin landmarks. A nd a custom designed patient positioning verification tool (PPVT) was used to check the patient alignment and correct the patient repositioning before radiosurgery. In this study, We investigate the selected 8 meta static spinal tumor cases. All type of tumors commonly closed to thoracic spinal code. To evaluate the isocenter positioning, real time patient alignment and positioning monitoring was carried out for comparing the current 3-dimensional position of markers with those of an initial reference positions. For a selected patient case, we have check the isocenter positioning per every 20 millisecond for 45 seconds during spinal radiosurgery. In this study, real time average isocenter positioning translation were 0.07±0.17 mm, 0.11±0.18 mm, 0.13±0.26 mm, and 0.20±0.37 mm in the x (lateral), y (longitudinal), z (vertical) directions and mean spatial error, respectively. And body rotations were 0.14±0.07 o , 0.11±0.07 o , 0.03±0.04 o in longitudinal, lateral, table directions and mean body rotation 0.20±0.11 o , respectively. In this study, the maximum mean deviation of real time isocenter positioning translation during spinal radiosurgery was acceptable accuracy clinically.

Comparison of IMRT and VMAT Techniques in Spine Stereotactic Radiosurgery with International Spine Radiosurgery Consortium Consensus Guidelines

Stereotactic body radiation therapy (SBRT) is increasingly used to treat spinal metastases. To achieve the highest steep dose gradients and conformal dose distributions of target tumors, intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) techniques are essential to spine radiosurgery. The purpose of the study was to qualitatively compare IMRT and VMAT techniq ues with International Spine Radiosurgery Consortium (ISRC) contoured consensus guidelines for target volume definition. Planning target volume (PTV) was categorized as T B, TBPT and TST depending on sectors involved; TB (vertebral body only), TBPT (vertebral body+ pedicle+transverse process), and TST (spinous process+transverse process). Three patients treated for spinal tumor in the cervical, thoracic, and lumbar region were selected. Each tumor was contoured by the definition from the ISRC guideline. Maximum spinal cord dose were 12.46 Gy, 12.17 Gy and 11.36 Gy for T B, TBPT and TST sites, and 11.81 Gy, 12.19 Gy and 11.99 Gy for the IMRT, RA1 and RA2 techniques, respectively. Average fall-off dose distance from 90% to 50% isodose line for TB, TBPT, and TST sites were 3.5 mm, 3.3 mm and 3.9 mm and 3.7 mm, 3.7 mm and 3.3 mm for the IMRT, RA1 and RA2 techniques, respectively. For the most complicated target TBPT sites in the cervical, thoracic and lumbar regions, the conformity index of the IMRT, RA1 and RA2 is 0.621, 0.761 and 0.817 and 0.755, 0.796 and 0.824 fo r rDHI. Both IMRT and VMAT techniques delivered high conformal dose distributions in spine stereotactic radiosurgery. However, if the target volume includes the vertebral body, pedicle, and transverse process, IMRT planning resulted in insufficient conformity index, compared to VMAT planning. Nevertheless, IMRT technique was more effective in reducing the maximum spinal cord dose compared to RA1 and RA2 techniques at most sites.

Review of stereotactic radiosurgery for intramedullary spinal lesions.

Stereotactic radiosurgery (SR) represents an increasingly utilized modality in the treatment of intracranial and extracranial pathologies. Stereotactic spine radiosurgery (SSR) uses an alternative strategy to increase the probability of local control by delivering large cumulative doses of radiation therapy (RT) in only a few fractions. SSR in the treatment of intramedullary lesions remains in its infancy-this review summarizes the current literature regarding the use of SSR for treating intramedullary spinal lesions. Several studies have suggested that SSR should be guided by the principles of intracranial radiosurgery with radiation doses placed no further than 1-2mm apart, thereby minimizing exposure to the surrounding spinal cord and allowing for delivery of higher radiation doses to target areas. Maximum dose-volume relationships and single-point doses with SSR for the spinal cord are currently under debate. Prior reports of SR for intramedullary metastases, arteriovenous malformations, ependymomas, and hemangioblastomas demonstrated favorable outcomes. In the management of intrame-dullary spinal lesions, SSR appears to provide an effective and safe treatment compared to conventional RT. SSR should likely be utilized for select patient-scenarios given the potential for radiation-induced myelopathy, though high-quality literature on SSR for intramedullary lesions remains limited.

Interview: Current state of brain and spine radiosurgery and future applications.

Arjun Sahgal works in the field of high-precision stereotactic radiation to the brain and spine. After training at the University of Toronto (ON, Canada) in radiation oncology, he completed a fellowship at the University of California, San Francisco (CA, USA) in brain and spine radiosurgery with Professor David Larson. Since then, he has been recognized as a national and international clinical expert and research leader in radiosurgery. His main focus is on developing spine stereotactic body radiotherapy (SBRT), also known as spine radiosurgery, as an effective therapy for patients with spinal tumors. Research achievements include publishing spinal cord tolerance guidelines for spine SBRT as part of an international multi-institutional effort. This work elucidated safe dose limits for the spinal cord specific to spine SBRT, and was the first of its kind. He has developed the spine SBRT program for the University of Toronto and is conducting the first Phase II clinical study on spine SBRT for metastases in Canada. He has also recently written national guidelines on behalf of the Canadian Association of Radiation Oncology (CARO) for the practice of spine, lung and liver SBRT, and continues to lead national and international multi-institutional groups dedicated to spine and brain radiosurgery research.

Radiosurgery for benign tumors of the spine using the Synergy S with cone-beam computed tomography image guidance

There is a growing body of evidence to support the safe and effective use of spine radiosurgery. However, there is much less experience regarding the use of radiosurgery for the treatment of benign as opposed to malignant spine tumors. This study represents an evaluation of, and reporting on, the technical aspects of using a dedicated radiosurgery system for the treatment of benign spine tumors. Forty-five consecutive benign spine tumors were treated using the Elekta Synergy S 6-MV linear accelerator with a beam modulator and cone-beam computed tomography (CBCT) image guidance technology for target localization. The study cohort included 16 men and 29 women, ranging in age from 23 to 88 years (mean age 52 years). There were 14 cervical, 12 thoracic, 14 lumbar, and 5 sacral tumors. Forty-one lesions (91%) were intradural. The most common histological types of tumor were schwannoma, neurofibroma, and meningioma. Indications for radiosurgery included primary treatment in 24 cases (53%) and treatment of recurrent or residual tumor after open resection in 21 cases (47%). No subacute or long-term spinal cord or cauda equina toxicity occurred during the follow-up period (median 32 months). The mean maximum dose received by the gross tumor volume (GTV) was 16 Gy (range 12-24 Gy) delivered in a single fraction in 39 cases. The mean lowest dose received to the GTV was 12 Gy (range 8-16 Gy). The GTV ranged from 0.37 to 94.5 cm(3) (mean 13.7 cm(3), median 5.9 cm(3)). In the majority of cases, a planning target volume expansion of 2 mm was employed (38 cases; 84%). The mean maximum point dose delivered to the spinal cord was 8.7 Gy (range 4-11.5 Gy); the mean volume of the spinal cord that received greater than 8 Gy was 0.9 cm(3) (range 0.0-5.1 cm(3)); and the mean dose delivered to 0.1 cm(3) of the spinal cord was 7.5 Gy (range 3-10.5 Gy). The mean maximum point dose delivered to the cauda equina was 10 Gy (range 0-13 Gy); the mean volume of the cauda equina that received greater than 8 Gy was 1.45 cm(3) (range 0.0-10.6 cm(3)); and the mean dose delivered to 0.1 cm(3) of the cauda equina was 8 Gy (range 0.5-11 Gy). In this study the authors describe the contouring and prescribed dose techniques used in the treatment planning and delivery of radiosurgery for benign neoplasms of the spine using CBCT image guidance. This technique may serve as an important reference for the performance of radiosurgery when one believes it is clinically indicated as a treatment modality for a benign spine tumor that is associated with both a high safety profile and a strong positive clinical outcome.

Spinal Cord Toxicity With High-dose, Single-fraction Spinal Stereotactic Radiosurgery

Spinal Cord Toxicity With High-dose, Single-fraction Spinal Stereotactic Radiosurgery

Variability in Spine Radiosurgery Treatment Planning -- Results of an International Multi-institutional Study

Radiosurgery (RS) for vertebral metastases has shown promising results in terms of pain and tumor control. However, there remains significant variability and little consensus regarding contouring and treatment planning. The aim of this study was to quantify the variability in the planning process according to RS practice between five international centers.

A Multinational Report on Methods for Institutional Credentialing for Spine Radiosurgery

A Multinational Report on Methods for Institutional Credentialing for Spine Radiosurgery

Dosimetric Accuracy of Ray-tracing Algorithm for Treatment of Thoracic Spine Lesions Using Robotic Radiosurgery

Dosimetric Accuracy of Ray-tracing Algorithm for Treatment of Thoracic Spine Lesions Using Robotic Radiosurgery