The rationale and development of a CyberKnife© registry for pediatric patients with CNS lesions.

BACKGROUND: CyberKnife© Radiosurgery (CKRS) is a recognized treatment concept for CNS lesions in adults due to its high precision and efficacy beside a high patient comfort. However, scientific evidence for this treatment modality in pediatric patients is scarce. A dedicated registry was designed to document CyberKnife© procedures in children, aiming to test the hypothesis that it is safe and efficient for the treatment of CNS lesions. METHODS: The CyberKnife© registry is designed as a retrospective and prospective multicenter observational study (German Clinical Trials Register ( https://www.drks.de ), DRKS-ID 00016973). Patient recruitment will be ongoing throughout a 5-year period and includes collection of demographic, treatment, clinical, and imaging data. Follow-up results will be monitored for 10 years. All data will be registered in a centralized electronic database at the Charité-Universitätsmedizin. The primary endpoint is stable disease for benign and vascular lesions at 5 years of follow-up and local tumor control for malign lesions at 1- and 2-year follow-up. Secondary endpoints are radiation toxicity, side effects, and neurocognitive development. CONCLUSION: The CyberKnife© registry intends to generate scientific evidence for all treatment- and outcome-related aspects in pediatric patients with treated CNS lesions. The registry may define safety and efficacy of CKRS in children and serve as a basis for future clinical trials, inter-methodological comparisons and changes of treatment algorithms.

Breathing-motion-compensated robotic guided stereotactic body radiation therapy : Patterns of failure analysis.

PURPOSE: We retrospectively evaluated the patterns of failure for robotic guided real-time breathing-motion-compensated (BMC) stereotactic body radiation therapy (SBRT) in the treatment of tumors in moving organs. PATIENTS AND METHODS: Between 2011 and 2016, a total of 198 patients with 280 lung, liver, and abdominal tumors were treated with BMC-SBRT. The median gross tumor volume (GTV) was 12.3 cc (0.1-372.0 cc). Medians of mean GTV BEDα/ß =10 Gy (BED = biological effective dose) was 148.5 Gy10 (31.5-233.3 Gy10) and prescribed planning target volume (PTV) BEDα/ß =10 Gy was 89.7 Gy10 (28.8-151.2 Gy10), respectively. We analyzed overall survival (OS) and local control (LC) based on various factors, including BEDs with α/ß ratios of 15 Gy (lung metastases), 21 Gy (primary lung tumors), and 27 Gy (liver metastases). RESULTS: Median follow-up was 10.4 months (2.0-59.0 months). The 2­year actuarial LC was 100 and 86.4% for primary early and advanced stage lung tumors, respectively, 100% for lung metastases, 82.2% for liver metastases, and 90% for extrapulmonary extrahepatic metastases. The 2­year OS rate was 47.9% for all patients. In uni- and multivariate analysis, comparatively lower PTV prescription dose (equivalence of 3 × 12-13 Gy) and higher average GTV dose (equivalence of 3 × 18 Gy) to current practice were significantly associated with LC. For OS, Karnofsky performance score (100%), gender (female), and SBRT without simultaneous chemotherapy were significant prognostic factors. Grade 3 side effects were rare (0.5%). CONCLUSIONS: Robotic guided BMC-SBRT can be considered a safe and effective treatment for solid tumors in moving organs. To reach sufficient local control rates, high average GTV doses are necessary. Further prospective studies are warranted to evaluate these points.

Efficacy, safety and outcome of frameless image-guided robotic radiosurgery for brain metastases after whole brain radiotherapy.

Estimating efficacy, safety and outcome of frameless image-guided robotic radiosurgery for the treatment of recurrent brain metastases after whole brain radiotherapy (WBRT). We performed a retrospective single-center analysis including patients with recurrent brain metastases after WBRT, who have been treated with single session radiosurgery, using the CyberKnife® Radiosurgery System (CKRS) (Accuray Inc., CA) between 2011 and 2016. The primary end point was local tumor control, whereas secondary end points were distant tumor control, treatment-related toxicity and overall survival. 36 patients with 140 recurrent brain metastases underwent 46 single session CKRS treatments. Twenty one patients had multiple brain metastases (58%). The mean interval between WBRT and CKRS accounted for 2 years (range 0.2-7 years). The median number of treated metastases per treatment session was five (range 1-12) with a tumor volume of 1.26 ccm (mean) and a median tumor dose of 18 Gy prescribed to the 70% isodose line. Two patients experienced local tumor recurrence within the 1st year after treatment and 13 patients (36%) developed novel brain metastases. Nine of these patients underwent additional one to three CKRS treatments. Eight patients (22.2%) showed treatment-related radiation reactions on MRI, three with clinical symptoms. Median overall survival was 19 months after CKRS. The actuarial 1-year local control rate was 94.2%. CKRS has proven to be locally effective and safe due to high local tumor control rates and low toxicity. Thus CKRS offers a reliable salvage treatment option for recurrent brain metastases after WBRT.

COMP Report: CPQR technical quality control guidelines for CyberKnife® Technology.

The Canadian Organization of Medical Physicists (COMP), in close partnership with the Canadian Partnership for Quality Radiotherapy (CPQR) has developed a series of Technical Quality Control (TQC) guidelines for radiation treatment equipment. These guidelines outline the performance objectives that equipment should meet in order to ensure an acceptable level of radiation treatment quality. This particular TQC contains detailed performance objectives and safety criteria for CyberKnife® Technology. The quality control recommendations in this document are based upon previously published guidelines and the collective experience of all Canadian sites using this technology. This TQC guideline has been field tested at the newest Canadian CyberKnife installation site and includes recommendations for quality control of the Iris™ and InCise™ MLC collimation systems.

Clinical usefulness of MLCs in robotic radiosurgery systems for prostate SBRT.

Stereotactic body radiation therapy (SBRT) using recently introduced multileaf collimators (MLC) is preferred over circular collimators in the treatment of localized prostate cancer. The objective of this study was to assess the clinical usefulness of MLCs in prostate SBRT by comparing the effectiveness of treatment plans using fixed collimators, variable collimators, and MLCs and by ensuring delivery quality assurance (DQA) for each. For each patient who underwent conventional radiation therapy for localized prostate cancer, mock SBRT plans were created using a fixed collimator, a variable collimator, and an MLC. The total MUs, treatment times, and dose-volume histograms of the planning target volumes and organs at risk for each treatment plan were compared. For DQA, a phantom with a radiochromic film or an ionization chamber was irradiated in each plan. We performed gamma-index analysis to evaluate the consistency between the measured and calculated doses. The MLC-based plans had an ~27% lower average total MU than the plans involving other collimators. Moreover, the average estimated treatment time for the MLC plan was 31% and 20% shorter than that for the fixed and variable collimator plans respectively. The gamma-index passing rate in the DQA using film measurements was slightly lower for the MLC than for the other collimators. The DQA results acquired using the ionization chamber showed that the discrepancies between the measured and calculated doses were within 3% in all cases. The results reinforce the usefulness of MLCs in robotic radiosurgery for prostrate SBRT treatment planning; most notably, the total MU and treatment time were both reduced compared to the cases using other types of collimators. Moreover, although the DQA results based on film dosimetry yielded a slightly lower gamma-index passing rate for the MLC than for the other collimators, the MLC accuracy was determined to be sufficient for clinical use.

Robotic radiosurgery for the treatment of liver metastases.

AIM: This study evaluates the toxicity and outcome in patients treated with robotic radiosurgery for liver metastases. BACKGROUND: Modern technologies allow the delivery of high doses to the liver metastases while lowering the dose to the neighboring organs at risk. Whether this dosimetric advantage translates into clinical benefit is not well known yet. METHODS AND MATERIALS: A total of 9 patients with 17 liver metastases have been treated with robotic stereotactic body radiotherapy SBRT from March 2011 to December 2014. Local response to SBRT was graded by the Response Evaluation Criteria in Solid Tumors criteria to describe change in treated tumor lesion. Adverse events after SBRT were graded on a 1-5 scale according to the National Cancer Institute common terminology criteria for adverse events v4.0. RESULTS: Patients received either three (78%) or five (22%) fractions. Patients were treated with a mean fraction dose of 14 Gy with a range from 9 to 20 Gy. The median total radiation dose provided to patients was 45 Gy with a range of 45-60 Gy. Four out of the 17 (23.5%) treated lesions had a complete response, 9 (53%) partial response and 3 (17.6%) stable disease. With a median follow-up of 15.2 months after SBRT treatment, local control and overall survival rated were 89% and 66%, respectively. No patient experienced grade ≥3 toxicity. The most common toxicity reported was asthenia. Only two patients had nausea and diarrhea, 10 and 14 days after SBRT, respectively. CONCLUSIONS: Robotic radiosurgery is a safe and effective local treatment option for secondary liver tumors. Further prospective studies are ongoing to determine long-term response and survival after robotic-SBRT for liver metastases.

Experience of CyberKnife Robotic Radiosurgery in treating intra and extra-cranial tumours: A review of outcomes.

OBJECTIVE: To determine the success rate and complication of CyberKnife Robotic Radiosurgery for treating intracranial and extra cranial tumours. METHODS: The cross-sectional observational study was carried out at the Department of CyberKnife Robotic Radiosurgery at the Jinnah Postgraduate Medical Centre, Karachi, and reviewed data related to a year from December 2012 to December 2013. Patients referred from different hospitals within and outside Pakistan for stereotactic radiosurgery were included. The patients had benign tumours less than 7cm size, post-operative residual tumour and recurrent tumour with post-radiotherapy. Patients were followed up every three months with contrast magnetic resonance imaging. Radiosurgery was considered successful if patients improved clinically with radiologically stable disease or if there was interval reduction in the size of tumour. SPSS 17 was used for data analysis. RESULTS: Initially, 260 patients were selected, but 9(3.5%) were lost, and the final sample size was 251(96.5%). Clinically successful outcome results were seen in 225(90%) patients, while 8(3%) showed no change in symptoms and 18(7%) patients' follow-up is awaited. Radiological improvement was noted in 218(87%); stable disease in 138(55%) and 80(32%) cases showed more than 30% reduction in size after 6-12 months of follow-up. Only 5(2%) cases showed subtle increase in size within 3-month interval due to post-radiation oedema. Acute transient post-radiation changes were seen in 25(10%) patients, sub-acute changes in 4(1.59%) and 1(0.3%) patient showed radionecrosis after 9-month interval. CONCLUSIONS: Cyberknife was an effective, safe and successful treatment alternative to surgery in benign and malignant tumours with low risk of post-radiotherapy complication compared to conventional radiation.

Evaluation of efficacy and safety of robotic stereotactic body radiosurgery and hypofractionated stereotactic radiotherapy for vertebral metastases.

AIM OF THE STUDY: The purpose of this study was to evaluate the efficacy and safety of applying CyberKnife (CK) radiosurgery in patients with spinal metastases. MATERIAL AND METHODS: Twenty-eight patients with vertebral metastases treated using the CK system were included in the study. Eleven patients suffered from pain, and in 1 case neurological symptoms were observed. The remaining patients were free from clinical symptoms of metastatic disease. The doses applied ranged between 8 and 40 Gy delivered in 4 fractions of 8-15 Gy. RESULTS: In the first follow-up evaluation (mean 4.5 months after the treatment), pain was stable in 5 of 8 evaluable cases and in 3 regression occurred. The last follow-up examination (mean 11 months after stereotactic radiosurgery) revealed stable ailments in 3 of 6 evaluable cases, improvement in 3 and new complaints in another 4 patients. In 17 patients imaging studies were conducted after a mean time of 11 months after CK treatment. Stabilization was confirmed in 11, regression in 4 and progression in 2 cases. Median overall survival was 20.6 months. Median progression-free survival was 12.6 months. No side effects attributable to the treatment were observed, but during follow-up transient or permanent deterioration in neurological status as a consequence of disease progression was diagnosed in 4 patients. Delivery time of a single fraction ranged between 0.5 and 1.5 hours. CONCLUSIONS: Robotic stereotactic radiosurgery as part of multimodality therapy for metastatic spinal tumours is safe and effective. Because of long irradiation times, this kind of treatment is not suitable for patients in poor general condition.

End-to-end validation of fiducial tracking accuracy in robotic radiosurgery using MRI-only simulation imaging.

BACKGROUND: Image-guided radiation-therapy (IGRT)-based robotic radiosurgery using magnetic resonance imaging (MRI)-only simulation could allow for improved target definition with highly conformal radiotherapy treatments. Fiducial marker (FM)-based alignment is used with robotic radiosurgery treatments of sites such as the prostate because it aids in accurate target localization. Synthetic CT (sCT) images are generated in the MRI-only workflow but FMs used for IGRT appear as signal voids in MRIs and do not appear in MR-generated sCTs, hindering the ability to use sCTs for fiducial-based IGRT. PURPOSE: In this study we evaluate the fiducial tracking accuracy for a novel artificial fiducial insertion method in sCT images that allows for fiducial marker tracking in robotic radiosurgery, using MRI-only simulation imaging (MRI-only workflow). METHODS: Artificial fiducial markers were inserted into sCT images at the site of the real marker implantation as visible in MRI. Two phantoms were used in this study. A custom anthropomorphic pelvis phantom was designed to validate the tracking accuracy for a variety of artificial fiducials in an MRI-only workflow. A head phantom containing a hidden target and orthogonal film pair inserts was used to perform end-to-end tests of artificial fiducial configurations inserted in sCT images. The setup and end-to-end targeting accuracy of the MRI-only workflow were compared to the computed tomography (CT)-based standard. Each phantom had six FMs implanted with a minimum spacing of 2 cm. For each phantom a bulk-density sCT was generated, and artificial FMs were inserted at the implantation location. Several methods of FM insertion were tested including: (1) replacing HU with a fixed value (10000HU) (voxel-burned); (2) using a representative fiducial image derived from a linear combination of fiducial templates (composite-fiducial); (3) computationally simulating FM signal voids using a digital phantom containing FMs and inserting the corresponding signal void into sCT images (simulated-fiducial). All tests were performed on a CyberKnife system (Accuray, Sunnyvale, CA). Treatment plans and digital-reconstructed-radiographs were generated from the original CT and sCTs with embedded fiducials and used to align the phantom on the treatment couch. Differences in the initial phantom alignment (3D translations/rotations) and tracking parameters between CT-based plans and sCT-based plans were analyzed. End-to-end plans for both scenarios were generated and analyzed following our clinical protocol. RESULTS: For all plans, the fiducial tracking algorithm was able to identify the fiducial locations. The mean FM-extraction uncertainty for the composite and simulated FMs was below 48% for fiducials in both the anthropomorphic pelvis and end-to-end phantoms, which is below the 70% treatment uncertainty threshold. The total targeting error was within tolerance (<0.95 mm) for end-to-end tests of sCT images with the composite and head-on simulated FMs (0.26, 0.44, and 0.35 mm for the composite fiducial in sCT, head-on simulated fiducial in sCT, and fiducials in original CT, respectively. CONCLUSIONS: MRI-only simulation for robotic radiosurgery could potentially improve treatment accuracy and reduce planning margins. Our study has shown that using a composite-derived or simulated FM in conjunction with sCT images, MRI-only workflow can provide clinically acceptable setup accuracy in line with CT-based standards for FM-based robotic radiosurgery.

Co-relation of Portal Vein Tumour Thrombus Response With Survival Function Following Robotic Radiosurgery in Vascular Invasive Hepatocellular Carcinoma.

Background/aims: The aim of this study was to prospectively evaluate stereotactic body radiotherapy (SBRT) with robotic radiosurgery in hepatocellular carcinoma patients with macrovascular invasion (HCC-PVT). Materials and methods: Patients with inoperable HCC-PVT, good performance score (PS0-1) and preserved liver function [up to Child-Pugh (CP) B7] were accrued after ethical and scientific committee approval [Clinical trial registry-India (CTRI): 2022/01/050234] for treatment on robotic radiosurgery (M6) and planned with Multiplan (iDMS V2.0). Triple-phase contrast computed tomography (CT) scan was performed for contouring, and gross tumour volume (GTV) included contrast-enhancing mass within main portal vein and adjacent parenchymal disease. Dose prescription was as per risk stratification protocol (22-50 Gy in 5 fractions) while achieving the constraints of mean liver dose <15 Gy, 800 cc liver <8 Gy and the duodenum max of <24 Gy). Response assessment was done at 2 months' follow-up for recanalization. Patient- and treatment-related factors were evaluated for influence in survival function. Results: Between Jan 2017 and May 2022, 318 consecutive HCC with PVT patients were screened and 219 patients were accrued [male 92%, CP score: 5-7 90%, mean age: 63 years (38-85 yrs), Cancer of the Liver Italian Program <3: 84 (40%), 3-6117 (56%), infective aetiology 9.5%, performance status (PS): 0-37%; 1-56%]. Among 209 consecutive patients accrued for SBRT treatment (10 patients were excluded after accrual due to ascites and decompensation), 139 were evaluable for response assessment (>2 mo follow-up). At mean follow-up of 12.21 months (standard deviation: 10.66), 88 (63%) patients expired and 51 (36%) were alive. Eighty-two (59%) patients had recanalization of PVT (response), 57 (41%) patients did not recanalize and 28 (17%) had progressive/metastatic disease prior to response evaluation (<2 months). Mean overall survival (OS) in responders and non-responders were 18.4 [standard error (SE): 2.52] and 9.34 month (SE 0.81), respectively (P < 0.001). Mean survival in patients with PS0, PS1 and PS2 were 17, 11.7 and 9.7 months (P = 0.019), respectively. OS in partial recanalization, bland thrombus and complete recanalization was 12.4, 14.1 and 30.3 months, respectively (P-0.002). Adjuvant sorafenib, Barcelona Clinic Liver Classification stage, gender, age and RT dose did not influence response to treatment. Recanalization rate was higher in good PS patients (P-0.019). OS in patients with response to treatment, in those with no response to treatment, in those who are fit but not accrued and in those who are not suitable were 18.4, 9.34, 5.9 and 2.6 months, respectively (P-<0.001). Thirty-six of 139 patients (24%) had radiation-induced liver disease (RILD) [10 (7.2%) had classic RILD & 26 (19%) had non-classic RILD]. Derangement in CP score (CP score change) by more than 2 was seen in 30 (24%) within 2-month period after robotic radiosurgery. Eighteen (13%) had unplanned admissions, two patients required embolization due to fiducial-related bleeding and 20 (14%) had ascites, of which 9 (6%) patients required abdominocentesis. Conclusion: PVT response or recanalization after SBRT is a statistically significant prognostic factor for survival function in HCC-PVT.

AAPM task group report 135.B: Quality assurance for robotic radiosurgery.

AAPM Task Group Report 135.B covers new technology components that have been added to an established radiosurgery platform and updates the components that were not well covered in the previous report. Considering the current state of the platform, this task group (TG) is a combination of a foundational task group to establish the basis for new processes/technology and an educational task group updating guidelines on the established components of the platform. Because the technology discussed in this document has a relatively small user base compared to C-arm isocentric linacs, the authors chose to emphasize the educational components to assist medical physicists who are new to the technology and have not had the opportunity to receive in-depth vendor training at the time of reading this report. The TG has developed codes of practice, introduced QA, and developed guidelines which are generally expected to become enduring practice. This report makes prescriptive recommendations as there has not been enough longitudinal experience with some of the new technical components to develop a data-based risk analysis.

Accuracy of robotic radiosurgery in renal cell carcinoma.

PURPOSE: Although emerging clinical evidence supports robotic radiosurgery as a highly effective treatment option for renal cell carcinoma (RCC) less than 4 cm in diameter, delivery uncertainties and associated target volume margins have not been studied in detail. We assess intrafraction tumor motion patterns and accuracy of robotic radiosurgery in renal tumors with real-time respiratory tracking to optimize treatment margins. METHODS: Delivery log files from 165 consecutive treatments of RCC were retrospectively analyzed. Five components were considered for planning target volume (PTV) margin estimation: (a) The model error from the correlation model between patient breath and tumor motion, (b) the prediction error from an algorithm predicting the patient breathing pattern, (c) the targeting error from the treatment robot, (d) the inherent total accuracy of the system for respiratory motion tracking, and (e) the margin required to cover potential target rotation, simulated with PTV rotations up to 10°. RESULTS: The median tumor motion was 10.5 mm, 2.4 mm and 4.4 mm in the superior-inferior, left-right, and anterior-posterior directions, respectively. The root of the sum of squares of all contributions to the system's inaccuracy results in a minimum PTV margin of 4.3 mm, 2.6 mm and 3.0 mm in the superior-inferior, left-right and anterior-posterior directions, respectively, assuming optimal fiducial position and neglecting target deformation. CONCLUSIONS: We have assessed kidney motion and derived PTV margins for the treatment of RCC with robotic radiosurgery, which helps to deliver renal treatments in a more consistent manner and potentially further improve outcomes.

Reducing treatment time for robotic radiosurgery by considering path efficiency during node selection.

BACKGROUND: Robotic radiosurgery treatments allow for precise non-coplanar beam delivery by utilizing a robot equipped with a linac that traverses through a set of predetermined nodes. High quality treatment plans can be produced but treatment times can grow large, with one substantial component being the robot traversal time. PURPOSE: The aim of this study is to reduce the treatment time for robotic radiosurgery treatments by introducing algorithms for reducing the robot traversal time. The algorithms are integrated into a commercial treatment planning system. METHODS: First, an optimization framework for robotic radiosurgery planning is detailed, including a heuristic optimization method for node selection. Second, two methods aimed at reducing the traversal time are introduced. One utilizes a centrality measure focusing on the structure of the node network, while the other is based on the direct computation of traversal times during optimization. A comparison between plans with and without the time-reducing algorithms is made for three brain cases and one liver case with basis in treatment time, plan quality, monitor units, and network structure of the selected nodes. RESULTS: Large decreases in traversal times are obtained by the traversal time reducing algorithms, with reductions of up to 49 % in the brain cases and 31 % in the liver case. The resulting reductions in treatment times are up to 30 % and 13 %, respectively. Small differences in plan quality are observed, with similar dose-volume histograms, dose distributions, and conformity/gradient indices. CONCLUSIONS: The total treatment time of the robotic radiosurgery treatments can be reduced by selecting nodes with more efficient robot traversal paths, while maintaining plan quality.

Stereotactic ablative radiotherapy for treating primary head and neck cancer and locoregional recurrence: A comprehensive review of the literature.

Introduction: Although stereotactic ablative radiotherapy (SABR) has advance to standard-of-care for many different indications like lung and liver malignancies, it still remains in its infancy for treating head and neck cancer. Nevertheless there is a growing body of experience and evidence, which is summarized in this review Methods A thorough search of the literature was performed and critically reviewed both for SABR as a primary treatment as well as for treating locoregionally recurrent disease in a pre-irradiated field. Results: There exist only few prospective data published so far for treating head and neck cancer with SABR. In the primary situation especially implementing SABR as a boost after definitive radiotherapy or a single-modality for locally limited, small glottic cancer appear promising. On the other hand, SABR can be a useful modality for treating local recurrence in a pre-irradiated field. However, caution is needed in the case of proximity to a pre-irradiated carotid artery or other serial organs at risk. Usually only limited gross volumes are treated with 3-6 fractions every other day and a cumulative dose of 24-44 Gy in dedicated radiosurgery platforms or modern linacs with the possibility of online image-guidance and adequate immobilsation. Conclusions: SABR is an innovative, effective and promising treatment modality for small targets, especially in near proximity to organs at risk or in a pre-irradiated region. Prospective trials are further needed for this technique to become standard-of care.

Initial evaluation of intrafraction motion using frameless CyberKnife VSI system.

AIM: To analyze intrafraction movement in patients undergoing frameless robotic radiosurgery and evaluate the influence of image acquisition frequency on global accuracy. BACKGROUND: Stereotactic radiosurgery requires high spatial accuracy in dose delivery. In conventional radiosurgery, a rigid frame is used to guarantee a correct target alignment and no subsequent movement. Frameless radiosurgery with thermoplastic mask for immobilization cannot completely eliminate intrafraction patient movement. In such cases, it is necessary to evaluate its influence on global treatment accuracy. MATERIALS AND METHODS: We analyzed the intrafraction motion of the first 15 patients undergoing intracranial radiosurgery (39 fractions) with the CyberKnife VSI system at our institution. Patient position was measured at a 15-90-s interval and was used to estimate intrafraction patient movement. RESULTS: With our acquisition image protocol and immobilization device, the 99% displacement error was lower than 0.85 mm. The systematic movement components were lower than 0.05 mm and the random component was lower than 0.3 mm in the 3 translational axes. Clear linear time dependence was found in the random component. CONCLUSIONS: Selection of the X-ray image acquisition time is necessary to meet the accuracy required for radiosurgery procedures with the CyberKnife VSI system. We verified that our image acquisition protocol met the 1-mm criterion.

Prospective Evaluation of Response to Treatment, Survival Functions, Recurrence Pattern and Toxicity Profile in Indian Patients with Oligo-Brain Metastasis Treated with Only SRS.

Background: Prospective analysis of oligo-brain metastasis in Indian patients treated with SRS-only treatment. Methods: Between January 2017 and May 2022, 235 patients were screened and 138 histologically proven and radiologically confirmed. One to five brain metastasis patients aged more than 18 years with good Karnofsky performance status (KPS >70) accrued in ethical and scientific committee-approved prospective observational study protocol for treatment with only radiosurgery (SRS) with robotic radiosurgery (CyberKnife, CK) [AIMS IRB: 2020-071; CTRI No: REF/2022/01/050237]. Immobilization was performed with a thermoplastic mask, contrast CT simulation was performed with 0.625 mm slices, fused with T1 contrast/T2 FLAIR MRI images for contouring. Planning target volume (PTV) margin of 2-3 mm and a dose of 20-30 Gy in 1-5 fractions. Response to treatment, new brain lesions free survival, overall survival, and toxicity profile after CK were evaluated. Results: In total,: 138 patients with 251 lesions were accrued (median age 59 years (interquartile range [IQR] 49-67 years; female 51%; headache in 34%, motor deficit in 7%, KPS >90 in 56%; lung primary in 44%, breast in 30%; oligo-recurrence in 45%; synchronous oligo-metastases in 33%; adenocarcinoma primary in 83%). One hundred seven patients (77%) received upfront Stereotactic radiotherapy (SRS), 15 (11%) received postoperative SRS, 12 (9%) received whole brain radiotherapy (WBRT) before SRS, and 3 (2%) received WBRT plus SRS boost. The majority had solitary (56%) brain metastasis, 28% had two to three lesions, and 16% had four to five brain lesions. Frontal (39%) was the most common site. Median PTV was 15.5 mL (IQR - 8.1-28.5 mL). Seventy-one (52%) patients were treated with single fractions, 14% with three, and 33% with five fractions. Fraction schedules were 20-2 4 Gy/1fr; 27 Gy/3fr, and 25 Gy/5 fractions (mean BED 74.6 Gy [SD ± 48.1; mean MU 16608], mean treatment time was 49 min (range 17-118 min]. Twelve Gy normal brain volume was 40.8 mL (3.2%) (range 19.3-73.7 mL). At a mean follow-up of 15 months (SD 11.9 months; max 56 months), the mean actuarial OS after SRS-only treatment was 23.7 months (95% confidence interval [CI] 20-28). Further 124 (90%) patients had >3 months, 108 (78%) had >6 months, 65 (47%) had >12 months, and 26 (19%) had >24 months follow-up. Intracranial disease and extracranial disease were controlled in 72 (52.2%) and 60 (43.5%), respectively. "In-field" recurrence, "out-of-field," and "both in and out-of-field" recurrences were in 11%, 42%, and 46%, respectively. At the last follow-up, 55 patients (40%) were alive, 75 (54%) died due to disease progression, and the status of 8 (6%) patients was not known. Among 75 patients who died, 46 (61%) had extracranial disease progression, 12 (16%) had only intracranial progression, and 8 (11%) had unrelated causes. Also, 12/117 (9%) had radiological confirmation of radiation necrosis. Prognostication based on western patients (primary tumor type, number of lesions extracranial disease) showed similar outcomes. Conclusions: SRS alone in brain metastasis is feasible in the Indian subcontinent with similar survival outcomes, recurrence patterns, and toxicity as published in the western literature. Patient selection, dose schedule, and planning need to be standardized to have similar outcomes. WBRT can be safely omitted in Indian patients with oligo-brain metastasis. Western prognostication nomogram is applicable in the Indian patient population.

Meningioma involving the superior sagittal sinus: long-term outcome after robotic radiosurgery in primary and recurrent situation.

Objective: Treatment for meningiomas involving the superior sagittal sinus (SSS) is challenging and proved to be associated with higher risks compared to other brain locations. Therapeutical strategies may be either microsurgical (sub-)total resection or adjuvant radiation, or a combination of both. Thrombosis or SSS occlusion following resection or radiosurgery needs to be further elucidated to assess whether single or combined treatment is superior. We here present tumor control and side effect data of robotic radiosurgery (RRS) in combination with or without microsurgery. Methods: From our prospective database, we identified 137 patients with WHO grade I meningioma involving the SSS consecutively treated between 2005 and 2020. Treatment decisions were interdisciplinary. Patients underwent RRS as initial/solitary treatment (group 1), as adjuvant treatment after subtotal resection (group 2), or due to recurrent tumor growth after preceding microsurgery (group 3). Positive tumor response was assessed by MRI and defined as reduction of more than 50% of volume. Study endpoints were time to recurrence (TTR), time to RRS, risk factors for decreased survival, and side effects. Overall and specific recurrence rates for treatment groups were analyzed. Side effect data included therapy-related morbidity during follow-up (FU). Results: A total of 137 patients (median age, 58.3 years) with SSS meningiomas WHO grade I were analyzed: 51 patients (37.2%) in group 1, 15 patients (11.0%) in group 2, and 71 patients (51.8%) in group 3. Positive MR (morphological response) to therapy was achieved in 50 patients (36.4%), no response was observed in 25 patients (18.2%), and radiological tumor progression was detected in 8 patients (5.8%). Overall 5-year probability of tumor recurrence was 15.8% (median TTR, 41.6 months). Five-year probabilities of recurrence were 0%, 8.3.%, and 21.5% for groups 1-3 (p = 0.06). In multivariate analysis, tumor volume was significantly associated with extent of SSS occlusion (p = 0.026) and sex (p = 0.011). Tumor volume significantly correlated with TTR (p = 0.0046). Acute sinus venous thrombosis or venous congestion-associated bleedings did not occur in any of the groups. Conclusion: RRS for grade I meningiomas with SSS involvement represents a good option as first-line treatment, occasionally also in recurrent and adjuvant scenarios as part of a multimodal treatment strategy.

Long-term follow-up results of spine tumor treatment using high-dose radiotherapy after 3-dimensional-printed vertebral bodies implantation.

OBJECTIVE: To investigate the long-term safety and efficacy of high-dose radiotherapy after 3D-printed vertebral body implantation in the treatment of spinal tumors. METHODS: Thirty-three participants were recruited between July 2017 and August 2019. 3D-printed vertebral bodies were implanted in each participant, followed by postoperative robotic stereotactic radiosurgery at a dose of 35-40 Gy/5f. The tolerance of the 3D-printed vertebral body and the participant to the high-dose radiotherapy were evaluated. In addition, the local control of tumor and the local progression-free survival of the study participants following 3D-printed vertebral body implantation and high-dose radiotherapy were measured as indexes of effectiveness. RESULTS: Of the 33 participants included in the study, 30, including three participants (10%) with esophagitis of grade 3 or above and two participants (6.7%) with advanced radiation nerve injury, successfully underwent postoperative high-dose radiotherapy. The median follow-up was 26.7 months, and IQR was 15.9 months. Most participants had primary bone tumors with 27 cases (81.8%), and the rest had bone metastases in six cases (18.2%). After high-dose radiotherapy, the 3D-printed vertebrae maintained good vertebral stability and exhibited histocompatibility, without implant fractures. The local control rates were 100%, 88%, and 85% 6 months, 1 year, and 2 years after high-dose radiotherapy, respectively. Tumors recurred in four participants (12.1%) during the follow-up period. The median local progression-free survival after treatment was 25.7 months, with a range of 9.6-33.0 months. CONCLUSION: High-dose radiotherapy for spinal tumors after 3D-printed vertebral body implantation is feasible, elicits low toxicity, and yields satisfactory tumor control.

Robotic Radiosurgical Boost After Whole-Brain Radiotherapy for 12 Brain Metastases: En Bloc Consecutive Irradiation With Comprehensively Optimized Single Plan for Eight Lesions Totaling 118 cc.

General radiotherapeutic management for >10 brain metastases (BMs) totaling >100 cm3, including multiple large lesions (>10-30 cm3) in close proximity, demonstrated limited efficacy and/or safety. We describe a case of 12 BMs, summating 122.2 cm3, including a 39.6 cm3 maximum lesion and adjacent ones. The patient had an 8.1-year treatment history for recurrent/metastatic breast cancer refractory to endocrine and chemotherapy. BMs were treated with conventional whole-brain radiotherapy (WBRT) with 30 Gy/10 fractions (fr), followed by an immediate stereotactic radiosurgery (SRS) boost with 27 Gy/5 fr (52-64% isodoses) which covers the gross tumor boundaries of selected eight lesions (total 118.4 cm3). The SRS dose was defined to ensure the cumulative biologically effective dose (BED10) of just ≥80 Gy while minimizing the risk of radiation injury. The SRS was performed using a CyberKnife (CK) robotic system (Accuray Incorporated, Sunnyvale, California, United States) with a variable-sized collimator (10-40 mm), for which en bloc consecutive irradiation, using 215 beams based on a comprehensively optimized single plan (path), was adopted. The treatment time per fraction was ≤45 min (mean 5.6 min per lesion). Afterward, BMs demonstrated remarkable regression over six months, causing the total residual visible lesions of 12.6 cm3 (10.3%) at 11.4 months, despite the absence of obvious lesion shrinkage during the radiotherapy. WBRT, followed by an immediate 5-fr SRS boost with a total BED10 of 80 Gy to large and/or culprit lesions, can be an efficacious and safe treatment option for multiple BMs, totaling >120 cm3. En bloc consecutive irradiation with a single path provides overwhelmingly more efficient delivery for treating multiple lesions using CK in terms of irradiation time and comprehensive reduction of normal brain dose compared to individual planning. Volumetric-modulated arc-based >10-fr SRS with simultaneously integrated reduced-dose WBRT may be an alternative to further enhance efficacy and safety.

Image-Guided Robotic Radiosurgery for the Treatment of Lung Metastases of Renal Cell Carcinoma-A Retrospective, Single Center Analysis.

Pulmonary metastases are the most frequent site of metastases in renal cell carcinoma (RCC). Metastases directed treatment remains an important treatment option despite advances in systemic therapies. However, the safety and efficacy of robotic radiosurgery (RRS) for the treatment of lung metastases of RCC remains unclear. Patients with metastatic RCC and lung metastases treated by RRS were retrospectively analyzed for overall survival (OS), progression-free survival (PFS), local recurrence free survival (LRFS) and adverse events. The Kaplan-Meier method was used for survival analysis and the common terminology criteria for adverse events (CTCAE; Version 5.0) classification for assessment of adverse events. A total of 50 patients were included in this study. Median age was 64 (range 45-92) years at the time of RRS. Prior to RRS, 20 patients (40.0%) had received either tyrosine kinase inhibitors or immunotherapy and 27 patients (54.0%) were treatment naïve. In our patient cohort, the median PFS was 13 months (range: 2-93). LRFS was 96.7% after two years with only one patient revealing progressive disease of the treated metastases 13 months after RRS. Median OS was 35 months (range 2-94). Adverse events were documented in six patients (12%) and were limited to grade 2. Fatigue (n = 4) and pneumonitis (n = 2) were observed within 3 months after RRS. In conclusion, RRS is safe and effective for patients with metastatic RCC and pulmonary metastases. Radiation induced pneumonitis is specific in the treatment of pulmonary lesions, but not clinically relevant and survival rates seem favorable in this highly selected patient cohort. Future directions are the implementation of RRS in multimodal treatment approaches for oligometastatic or oligoprogressive disease.