✓ Radiosurgery for brain tumors has been well established in the radiation oncology and neurosurgery fields. Radiosurgery of extracranial tumors such as those involving the spine is, however, still in the early stage because of difficulties in patient immobilization and organ motion. The authors describe an image-guided procedure for intensity-modulated spinal radiosurgery that was developed at Henry Ford Hospital.
9103 Background: The role of thoracic radiation (TRT) is controversial for stage IV non-small cell lung cancer (NSCLC). A prospective study of 29 patients reported superior progression free survival with radical TRT. This study aimed to report the overall survival (OS) effect of TRT and examine whether the OS effect varies with the timing of TRT regarding to systemic therapy. Methods: Stage IV patients from the national cancer database (NCDB) 2005-2014 formed the base of the study population. TRT, dose and time effects were analyzed individually in patients treated with non-immune systemic therapy or immune therapy. The primary endpoint was OS. Kaplan-Meier test was used for the OS analysis. Results: A total of 334,702 patients were eligible. Median survival time (MST) was 5.2 months (mo). Younger age, female gender, non-African American, lower Charlson comorbidity score, and any TRT were all significantly associated with favorable OS (all P < 0.001). In 326,287 patients receiving non-immune systemic therapy, TRT was a significant factor for favorable OS (HR = 0.964, 95%CI 0.955-0.974, P < 0.001). Comparing to those receiving TRT before non-immune systemic therapy (n = 5,500, MST = 8.8 mo), patients with concurrent TRT-systemic treatments (within 30 days of systemic therapy) had significantly worse OS (n = 20,099, MST = 7.2 mo, P < 0.001), while patients receiving TRT after systemic therapy had the best OS (n = 6,064, MST = 11.2 mo, P < 0.001). In 4,639 patients treated with immune therapy, TRT was associated with significantly worse OS (n = 512, MST = 11.1 mo, P < 0.001), comparing to immune therapy alone (n = 4,127, MST = 14.1 mo). Patients received concurrent TRT had worst OS (n = 177, MST = 7.4 mo, P < 0.001), comparing to TRT before immune therapy (n = 165, MST = 12.2 mo) and TRT after immune therapy (n = 138, MST = 13.2 mo, P = 0.086). Conclusions: In patients with stage IV NSCLC, TRT seemed to be associated with better OS in those treated with non-immune systemic therapy but worse overall survival in patients receiving immune therapy. Concurrent TRT with any systemic therapy including immune therapy was associated with worse survival.
Purpose: To develop an image guided target localization technique to improve the patient positioning accuracy for brain radiosurgery and fractionated stereotactic radiotherapy using non‐invasive fixation. Materials and method: BrainLab stereotactic localization box system is used for the initial patient setup. The patient is immobilized using a thermal mask with a mouth bite piece. An image guided localization system (Novalis body system, BrainLab) is used to finely adjust the position after the initial setup. The system automatically fuses two X‐ray images with the corresponding DRR and gives the position offsets in 6 dimensions. The accuracy of the image guided localization system was evaluated in a rando phantom with a 2‐mm‐metal‐ball placed as the isocenter, and in 15 patients with total of 48 fractions for image fusion. Results: The phantom study showed that the positioning accuracy is within 1‐mm for various isocenter positions. The image fusion for each patient was checked carefully and could be evaluated easily due to its rigid structure and rich bony features. At least three distinguish features could be identified in each image, and a 1‐mm translational move generally induced a visible dis‐matching in these features. This suggests that the accuracy of alignment to the isocenter of the X‐ray system be better than 1‐mm. Considering that the isocenter of the X‐ray system could be different from the linac's, the overall positioning accuracy for the image guided system would be in the order of 1.4‐mm. The offsets of the fusion results was used for mutual testing between the image guided system and the stereotactic localization box system. The average offsets for the lateral, AP and longitudinal directions were −0.67±1.09, 0.44±1.09, and −0.84±1.44 mm, respectively. This is consistentwith the results of the non‐invasive immobilization techniques reported by other authors. Conclusion: The image guided system could improve the patient positioning accuracy.
Purpose: Scatter significantly limits the application of the dual-source cone-beam computed tomography by inducing scatter artifacts and degrading contrast-to-noise ratio, Hounsfield-unit accuracy, and image uniformity. Although our previously developed interleaved acquisition mode addressed the cross scatter between the 2 X-ray sources, it doubles the scanning time and doesn’t address the forward scatter issue. This study aims to develop a prepatient grid system to address both forward scatter and cross scatter in the dual-source cone-beam computed tomography. Methods: Grids attached to both X-ray sources provide physical scatter reduction during the image acquisition. Image data were measured in the unblocked region, while both forward scatter and cross scatter were measured in the blocked region of the projection for postscan scatter correction. Complementary projections were acquired with grids at complementary locations and were merged to form complete projections for reconstruction. Experiments were conducted with different phantom sizes, grid blocking ratios, image acquisition modes, and reconstruction algorithms to investigate their effects on the scatter reduction and correction. The image quality improvement by the prepatient grids was evaluated both qualitatively through the artifact reduction and quantitatively through contrast-to-noise ratio, Hounsfield-unit accuracy, and uniformity using a CATphan 504 phantom. Results: Scatter artifacts were reduced by scatter reduction and were removed by scatter correction method. Contrast-to-noise ratio, Hounsfield-unit accuracy, and image uniformity were improved substantially. The simultaneous acquisition mode achieved comparable contrast-to-noise ratio as the interleaved and sequential modes after scatter reduction and correction. Higher grid blocking ratio and smaller phantom size led to higher contrast-to-noise ratio for the simultaneous mode. The iterative reconstruction with total variation regularization was more effective than the Feldkamp, Davis, and Kress method in reducing noise caused by the scatter correction to enhance contrast-to-noise ratio. Conclusion: The prepatient grid system is effective in removing the scatter effects in the simultaneous acquisition mode of the dual-source cone-beam computed tomography, which is useful for scanning time reduction or dual energy imaging.
