Objective: In brain metastases management, radiosurgical treatment with CyberKnife^® System (CK) provides, despite a limited number of fractions, high dose to the target volume, with a concomitant reduction of dose to organs at risk (OARs). Volume delineation, a crucial moment in planning process, heavily relies on imaging technologies, such as computed tomography (CT), magnetic resonance imaging (MRI), Positron Emission Tomography (PET) with image fusion.
Patients and Methods: From November 2012 to October 2014 we treated 163 patients for brain metastases (311 treatments) with CK, an image-guided frameless robotic SRS/SRT. In the planning of the radiosurgical treatment we used a system of image fusion RM/simul-CT. We enrolled patients, aged ≥ 18 years, with single brain metastases resectable and unresectable size < 4.3 cm or with multiple brain metastases (no more than 3), all dimensions < 3.4 cm with a documented examination RM, with Karnofsky performance status (KPS) ≥ 70, with good prognosis calculated according to functional scoring criteria GPA (graded prognostic assessment). The treatments were performed in 77% with single fraction (range10-24 Gy), in 2% with two fractions (range 18-21 Gy), 18% with three fractions (range 18-24Gy), 3% with five fractions (range 20-25Gy). The dose was prescribed to 80%. All patients were evaluated with clinical and radiological follow-up every two months.
Results: Median follow-up was 9 months: overall survival was 14.7 months for patients with Breast Cancer metastases, 10.3 months in Melanoma/RCC e 7.66 months in Lung cancer. Time to Progression of lesions treated with radiosurgery (dose 10- 24 Gy in single fraction), assessed at follow-up according to RECIST criteria, was 23.6 months in Breast Cancer, 11.2 months in Lung cancer, 10.7 months in Melanoma / RCC. Furthermore, we verified the dose constraints and we calculated the median of maximum dose (Dmax) of the OARs. We did not record acute or late treatment-related effects.
Conclusions: The image fusion used for the delineation of target and OARs provided accuracy and uniformity for contouring and planning, ensuring respect of constraints, reduced toxicity, improved quality of life and increased in local control.