Dynamic intrafractional position monitoring with implanted fiducial markers for enhanced accuracy in radiotherapy of prostate cancer.

INTRODUCTION: Recent advances in the radiation therapy of prostate cancer have brought a shift toward moderate- and ultra-hypofractionated treatment schedules. Reducing safety margins can broaden the therapeutic window in stereotactic treatments and alleviate concerns for toxicity in high dose-per-fraction treatment schedules. Management of intrafractional motion is a necessity for stereotactic body radiation therapy (SBRT). It can be achieved by performing intrafractional image guidance and position corrections. We evaluate the suitability of such a novel prostate motion management system and its potential benefit for treatment accuracy. METHODS: Intrafractional IGRT was performed for 22 patients during 149 treatment sessions using repeated orthogonal kV-XR imaging of implanted fiducial markers with the ExacTrac Dynamic (EXTD) system. Position measurements were taken four times during each arc of the applied volumetric modulated arc therapy (VMAT). Position correction was performed if translational deviation exceeded 2 mm in any direction. RESULTS: Of 677 single EXTD measurements, 20.6% exceeded the predefined threshold of 2 mm 3D deviation. Without intrafractional corrections, 39.4% of all individual measurements would exceed the threshold. The 3D accuracy could thus significantly be improved, reducing mean 3D shifts from 1.97 (± 1.44) mm to 1.39 (± 1.01) mm by performing intrafractional IGRT. In total, 34% of all treatment sessions required correction of intrafractional position shifts. CONCLUSION: Monitoring of prostate motion using repeated intrafractional orthogonal kV-X-ray-based position measurements of implanted fiducial markers proved to be a reliable method to improve precision of stereotactic irradiations of the prostate. It can prevent unacceptable translation deviations in one third of all sessions.

Treatment of vascular soft tissue sarcomas with razoxane, vindesine, and radiation.

PURPOSE: In previous studies, razoxane and vindesine together with radiotherapy was proved to be effective in soft tissue sarcomas (STS). Because razoxane leads to a redifferentiation of pathological tumor blood vessels, it was of particular interest to study the influence of this drug combination in vascular soft tissue sarcomas. METHODS AND MATERIALS: This open multicenter Phase II study was performed by the Austrian Society of Radiooncology. Among 13 evaluable patients (10 angiosarcomas and 3 hemangio-pericytomas), 9 had unresectable measurable disease, 3 showed microscopic residuals, and 1 had a resection with clear margins. They received a basic treatment with razoxane and vindesine supported by radiation therapy. Outcome measures were objective response rates, survival time, and the incidence of distant metastases. RESULTS: In nine patients with measurable vascular soft tissue sarcomas (eight angiosarcomas and one hemangiopericytoma), 6 complete remissions, 2 partial remissions, and 1 minor remission were achieved, corresponding to a major response rate of 89%. A maintenance therapy with razoxane and vindesine of 1 year or longer led to a suppression of distant metastases. The median survival time from the start of the treatment is 23+ months (range, 3-120+) for 12 patients with macroscopic and microscopic residual disease. The progression-free survival at 6 months was 75%. The combined treatment was associated with a low general toxicity, but attention must be given to increased normal tissue reactions. CONCLUSIONS: This trimodal treatment leads to excellent response rates, and it suppresses distant metastases when given as maintenance therapy.