ESTRO 2023 - Abstract Book

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ESTRO 2023

Conclusion At a mean observation time of >2 years, this study prospectively analyzed the potential impact of proton therapy in patients treated for meningioma. Patients reported an overall increase in employment rate, significant improvement in their financial situation and preservation and gain in their quality of life over time.

PO-1114 Single isocenter Multitarget Radiosurgery and multiple brain metastases: Preliminary Experience

R. Ciervide 1 , M. López 1 , J. Martí 1 , O. Hernando 1 , B. Álvarez 1 , Á. Montero 1 , E. Sánchez 1 , M. García-Aranda 1 , J. Valero 1 , X. Chen 1 , R. Alonso 1 , K. Rossi 1 , C. Cañadillas 1 , P. Fernandez-Letón 1 , C. Rubio 1

1 HM Hospitales, Radiation Oncology, Madrid, Spain

Purpose or Objective Introduction:

Although Stereotactic radiosurgery (SRS) in the treatment of limited brain metastasasis (BM) is widely accepted, there are still limitations for SRS in the management of numerous BM. Frameless single-isocenter multitarget (SIMT) SRS is a novel technique that allows rapid therapy delivery to multiple BM. We report dosimetric outcomes of our preliminary experience with this technique.

Materials and Methods Methods and Materials

We have reviewed dosimetric outcomes of patients with intact or resected brain metastases treated with SRS in 1 to 5 fractions using SIMT technique at our institution. Immobilization was accomplished using an SRS stereotactic mask. We used the multiple brain metastases Elements software for registration, image fusion and target contouring and dynamic conformal arc therapy for planning. The ExacTrac stereoscopic imaging system and a 6 degree of freedom couch were used for monitoring and correcting position and residual errors. Patient positioning was monitored either in real-time using surface tracking. Patients and dosimetric outcome’s characteristics are described.

Results Results

From May the 19th to October the 7th 2022, we have treated 21 patients with a total of 62 BM. Patients and dosimetric outcome’s characteristics are described in Table 1. With a median number of 3 metastases treated per patient and a median number of 1 isocenter, the median prescription dose was 21 Gy in 1 fraction. The median single target volume was 0,262 cm3 and the median cumulative target volume was 1,039 cm3. The median minimum and maximum dose were 99,2% and 115% respectively. Both the median conformity and gradient index were 1,28 and 5,62. Healthy brain tissue was assessed by median V12 (0,8cc) and V 20 (4,5cc) according to fractionation, 1 or 5 fractions respectively.