Room: ePoster Forums
Purpose: To evaluate plan quality of a single isocenter treatment planning method in comparison to a more conventional multiple isocenter dynamic conformal arc (MIDCA) approach. Multiple brain metastases were treated using an Elekta Agility beam limiting device (Elekta, Stockholm, Sweden) with a 5mm MLC leaf width at isocenter.
Methods: Five patients previously treated for brain metastasis using MIDCA on our Elekta Versa HD LINAC were replanned using Brainlabâ€™s Elements Brain Mets SRS (EBMS) software (Brainlab, Munich, Germany). Patients were randomly selected with variable number of lesions (n = 2 - 6) and target volumes (0.1 â€“ 7.17 cc). Inverse Paddick conformity (CI), Gradient index (GI), and volumes receiving 12 Gy, 6 Gy and 3 Gy were used as evaluation metrics.
Results: A high degree of conformity was achieved using EBMS (CI = 1.31 Â± 0.11) compared to MIDCA (CI = 1.48 Â± 0.22). Normal tissue exposure and low dose spread to the brain was higher for MIDCA, (V12 = 5.60 Â± 4.58 cc, V6 = 48.12 Â± 25.85 cc, and V3 = 183.76 Â± 110.40 cc) compared to using EBMS, (V12 = 5.43 Â± 4.39 cc, V6 = 44.85 Â± 23.91 cc, and V3 = 143.98 Â± 83.53 cc). Mean dose fall-off for both approaches was comparable (GI (EBMS) = 4.84 Â± 0.95, GI (MIDCA)â‚? = 4.75 Â± 1.17). Treatment delivery time was notably shorter for the EBMS plans at 25 min compared to 48 min for MIDCA plans.
Conclusion: The cases studied show slightly higher conformity, improved normal tissue sparing, and more efficient treatment delivery for the automated brain metastases planning algorithm compared to the MIDCA approach.
Not Applicable / None Entered.