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Purpose: To develop a specialist-based consensus of cochlear contouring to be used in patients undergoing stereotactic radiosurgery (SRS) treatment for vestibular schwannoma. Methods and Materials: Representative computed tomography (CT) and magnetic resonance imaging (MRI) were used for cochlear contouring. The semicircles, cochlea, vestibule, and internal acoustic meatus were delineated by 7 radiation oncology department physicians and reviewed by neuroradiologists. A total of 12 cases accrued from a single academic institution were studied for a similarity analysis by the Dice coefficient. Results: The suggested guideline is an easily reproductive tool that allows radiation oncologists to accurately contour the vestibulocochlear system to avoid toxicity due to inadequate dosimetry of organs at risk. This could be a useful tool even for non-vestibular schwannoma radiation therapy. The Dice coefficient suggests reproducible results as long as the following contouring recommendations are observed. Conclusions: The template for vestibulocochlear delineation may be useful for an adequate organs at risk definition. Future studies are required to find specific constraints for each segment of the vestibulocochlear system, and to mitigate interobserver variations.
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BACKGROUND: This study aims to assess the clinical outcomes of patients with spine metastases who underwent stereotactic ablative radiation therapy (SABR) as part of their treatment. SABR has arisen as a contemporary treatment option for spinal metastasis patients with good prognoses. MATERIALS AND METHODS: Between November 2010 and September 2018, Spinal SABR was performed in patients with metastatic disease in different settings: radical (SABR only), postoperative (after decompression and/or fixation surgery), and reirradiation. Local control (LC), pain control, overall survival (OS) and toxicities were reported. RESULTS: Eighty-five patients (corresponding to 96 treatments) with spine metastases were included. The median age was 59 years (range, 23-91). In most SA BR (82.3%, n = 79) was performed as the first local spine treatment, while in 12 settings (12.5%), fixation and/or decompression surgery was performed prior to SABR. Two-year overall survival rate was 74.1%, and median survival was 19 months. The LC rate at 2 years was 72.3%. With regard to pain control, among 67 patients presenting with pain before SA BR, 83.3% had a complete response, 12.1% had a partial response, and 4.6% had progression. Vertebral compression fractures occurred in 10 patients (11.7%), of which 5 cases occurred in the reirradiation setting. Radiculopathy and myelopathy were not observed. No grade III or IV toxicities were seen. CONCLUSION: This is the first study presenting a Brazilian experience with spinal SA BR, and the results confirm its feasibility and safety. SABR was shown to produce good local and pain control rates with low rates of adverse events.
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We undertook a structured review of stereotactic radiosurgery (SRS) using linear particle accelerator (linac) equipment, focusing on volumetric modulated arc therapy (VMAT) technology, and frameless image-guided radiotherapy (IGRT), for the treatment of brain metastases. We analyzed the role of linac SRS and its clinical applications, exploring stereotactic localization. Historically, there was a shift from fixed frames to frameless approaches, moving toward less invasive treatments. Thus, we reviewed the concepts of VMAT for multiple-target applications, comparing its dosimetric and technical features to those of other available techniques. We evaluated relevant technical issues and discussed the planning parameters that have gained worldwide acceptance to date. Thus, we reviewed the current literature on the clinical aspects of SRS, especially its main indications and how the advantages of VMAT may achieve clinical benefits in such scenarios. Finally, we reported our institutional results on IGRT-VMAT for SRS treatments for patients with multiple brain metastases.