Abstract
BackgroundTo evaluate the role of RapidArc (RA) for stereotactic radiosurgery (SRS) of benign brain lesions in comparison to GammaKnife (GK) based technique.MethodsTwelve patients with vestibular schwannoma (VS, n = 6) or cavernous sinus meningioma (CSM, n = 6) were planned for both SRS using volumetric modulated arc therapy (VMAT) by RA. 104 MV flattening filter free photon beams with a maximum dose rate of 2400 MU/min were selected. Data were compared against plans optimised for GK. A single dose of 12.5 Gy was prescribed. The primary objective was to assess treatment plan quality. Secondary aim was to appraise treatment efficiency.ResultsFor VS, comparing best GK vs. RA plans, homogeneity was 51.7 ± 3.5 vs. 6.4 ± 1.5%; Paddick conformity Index (PCI) resulted 0.81 ± 0.03 vs. 0.84 ± 0.04. Gradient index (PGI) was 2.7 ± 0.2 vs. 3.8 ± 0.6. Mean target dose was 17.1 ± 0.9 vs. 12.9 ± 0.1 Gy. For the brain stem, D1cm3 was 5.1 ± 2.0 Gy vs 4.8 ± 1.6 Gy. For the ipsilateral cochlea, D0.1cm3 was 1.7 ± 1.0 Gy vs. 1.8 ± 0.5 Gy. For CSM, homogeneity was 52.3 ± 2.4 vs. 12.4 ± 0.6; PCI: 0.86 ± 0.05 vs. 0.88 ± 0.05; PGI: 2.6 ± 0.1 vs. 3.8 ± 0.5; D1cm3 to brain stem was 5.4 ± 2.8 Gy vs. 5.2 ± 2.8 Gy; D0.1cm3 to ipsi-lateral optic nerve was 4.2 ± 2.1 vs. 2.1 ± 1.5 Gy; D0.1cm3 to optic chiasm was 5.9 ± 3.1 vs. 4.5 ± 2.1 Gy. Treatment time was 53.7 ± 5.8 (64.9 ± 24.3) minutes for GK and 4.8 ± 1.3 (5.0 ± 0.7) minutes for RA for schwannomas (meningiomas).ConclusionsSRS with RA and FFF beams revealed to be adequate and comparable to GK in terms of target coverage, homogeneity, organs at risk sparing with some gain in terms of treatment efficiency.
Highlights
To evaluate the role of RapidArc (RA) for stereotactic radiosurgery (SRS) of benign brain lesions in comparison to GammaKnife (GK) based technique
SRS with RA and FFF beams revealed to be adequate and comparable to GK in terms of target coverage, homogeneity, organs at risk sparing with some gain in terms of treatment efficiency
Volumes and dose prescriptions Six Vestibular Schwannoma (VS) cases who were treated with RA technique and 6 cavernous sinus meningiomas (CSM) cases who were treated by GK formed the basis of this study
Summary
To evaluate the role of RapidArc (RA) for stereotactic radiosurgery (SRS) of benign brain lesions in comparison to GammaKnife (GK) based technique. Earlier detection with widespread use of MR imaging prompts the patient and the clinician to treatment, when. Intracranial meningiomas are mostly benign tumors (WHO grade I) in 90-95% of the cases. Clinical behavior and treatment strategies depend on the location, size and proximity to critical structures. Surgical treatment is preferred for accessible tumors and gross total resection achieves >90% local control rates. Surgery for the meningiomas in the skull base like cavernous sinus meningiomas (CSM) carries high morbidity risk. SRS for CSM with maximum diameter less than 3 to 4 cm and with some distance from critical structures provides high local control rates with reasonable morbidity [1]
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