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A Characterization of LinaTech New Mini-MLC D2SRS

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C Kabat

C Kabat*, H Parenica , N Kirby , K Rasmussen , D Saenz , N Papanikolaou , S Stathakis , University of Texas HSC SA, San Antonio, TX


SU-I-GPD-T-623 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: Stereotactic radiosurgery requires that the dose to the tumor be delivered with a high degree of conformity and precision. To facilitate SRS requirements, micro-MLC systems have been developed to better archive these tighter stringencies. LinaTech’s newly developed D2SRS mini-MLC system allows for much precision with 2 mm thick leaves at isocenter in addition to a dual camera system for directly measuring SSD. It is our goal to investigate the beam characteristics of a newly developed D2SRS mini-MLC system by LinaTech for radiosurgery/radiotherapy.

Methods: Physical measurements for small profiles were taken at 100 SSD in a PTW MP3-M water tank using a TN60012 micro-diode, 0.0016 cc pinpoint, and 0.004 mm diamond chambers. Square field sizes ranged from 0.7 cm to 12 cm with profiles at depths of 1.5 cm, 5 cm, 10 cm, 15 cm, and 20 cm tracing both in the in-plane and cross-plane was obtained using PTW MEPHYSTO software with step sizes of 0.2 mm. For all field sizes, 6 MV was used with a dose rate of 500 MU/min. MLC’s were reviewed for positional accuracies using both a picket fence and reverse picket fence.

Results: MLC leakage was found to be 1.6% under tungsten leaves with 7.5 cm height. Radiation field size vs light field was assessed to be within 0.2 cm. The penumbra was measured to be approximately 2 mm smaller than the respective open field without the add-on MLC. Using picket fence tests it was determined that a minimal deviations on the order of 0.1 mm in leaf positional accuracy exists.

Conclusion: Using the measurements from the profiles, PDDs and output factors, a beam model can be completed using the dedicated treatment planning software. Overall, the Linatech D2SRS mini-MLC was deemed suitable for SRS/SRT/SBRT/IMRT treatments in our clinic.

Funding Support, Disclosures, and Conflict of Interest: Supported in part by CPRIT Training Grant (RP 170345)

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