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Analysis of Intrafraction Movement in Patients Who Underwent SRS and FSRT with Frameless Double Shell Positioning System

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S Andavar

Senni Andavar*, A Dhiman , V Roshan , Shri Mata Vaishno Devi Narayana Superspeciality Hospital, Jammu, Jammu and Kashmir


TU-C3-GePD-TT-1 (Tuesday, August 1, 2017) 10:30 AM - 11:00 AM Room: Therapy ePoster Theater

Purpose: Analysis of Intrafraction movement in patients who underwent SRS and FSRT with frameless Double shell positioning system.

Methods: The Macromedics DSPS is a new fixation system for brain radiosurgery. It consists of a facemask along with moldable headrest. For this study we have taken 9 patients who already underwent SRS and FSRT radiosurgery using DSPS mask immobilization. The treatment plans was generated in MONACO version 5.11.01 treatment planning system. For each patient, X-ray volumetric images were taken during the initial patient setup, in-between the treatment delivery and end of the treatment delivery to verify the Intrafraction patient movement. The corrected patient position coordinates during treatment was used to estimate the Intrafraction patient movement. The translational and rotational movement records were obtained from the imaging system.

Results: A total of 60 data sets and 360 translation and rotational of X-ray images were analyzed in this study. The individual and population systematic and random errors were calculated to see the effectiveness of DSPS in achieving the immobilization and reproducible patient positioning. The random errors and systematic errors in inferior/superior, anterior/posterior and left/right translational movement were 0.09cm, 0.07cm and 0.08 cm and 0.017cm, 0.042cm, 0.053 cm respectively. As per our image acquisition protocol 99% displacement was lower than 1mm.

Conclusion: The Frameless radiosurgery with standard thermoplastic mask immobilization cannot completely eliminate Interfraction patient movement. The results presented in this confirm the high positioning accuracy of patients with the use of double shell positioning system for the cranial radiosurgery.

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