(Sunday, 7/14/2019) 3:30 PM - 4:00 PM
Room: Exhibit Hall | Forum 4
Purpose: To evaluate two automatic monoisocentric treatment planning techniques for multiple brain metastases
Methods: Nineteen patients who underwent treatment for multiple brain metastases (3-10 lesions) were used for this study. Their clinical plans were originally generated with VMAT technique in Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA). Using the same beam geometry, these patients were replanned with a Knowledge-based Planning (KBP) SRS model based on 100 previously treated monoisocentric SRS plans in Eclipse. The same cohort of patients were replanned with the Brainlab Multiple Brain Mets (MBM) SRS software (Munich, Germany) using noncoplanar dynamic conformal arcs. Both techniques were designed using a single isocenter and automatically created volumetrically optimized plans after all metastases have been outlined. All the plans were optimized and calculated only once without further manual tuning. The planning times were recorded from the beginning of assigning PTV for optimization to the end of dose calculation. The PTV coverage, conformity index (CI) for all lesions, monitor unit, and the planning time were recorded and compared.
Results: The mean values of PTV coverage were 99.6% and 99.5% for KBP and MBM plans, respectively. Mean ± standard deviation values of CI were 1.33 ± 0.30 and 1.65 ± 0.42; planning times were 19 ± 4 and 6 ± 1 minutes for KBP and MBM plans, respectively. The mean value of monitor units in KBP plans was 2594 ± 1658, which is significantly lower than the MBM monitor units of 3151 ± 2072.
Conclusion: Both automatic planning techniques produced clinically acceptable plans. The planning times were 3 times longer on average for KBP planning technique as compare with MBM planning technique. MBM SRS planning software yielded equivalent PTV coverage and CI, but required significantly higher monitor units as compared to KBP plans, which translate to longer treatment times.
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