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Artifacts, Registration and Radiobiological Relevance in SRS Planning of Vestibular Schwannoma

H Erra Sriramulu1*, (1) Kuwait Cancer Control Center, Kuwait, KW


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: Geometric and Registration accuracy is assessed and Slicer DTI software was used for the assessment of fibers for the Planning of Vestibular Schwannoma. Radiobiological assessment is also done to improve outcome.
Methods: machine with mask was used for SRS treatment. T1(SPGR), T2(FSE) , Fiesta and DTI(Diffusion Tensor Imaging) were acquired. Imaging Accuracy is calculated for T2, Fiesta with T1 using Mates Mutual Information(MMI) Metric test in slicer by modifying sampling and number of bins. DTI nyquist ghosting impact is analyzed. DTI baseline image is coregistered with T2 and then with T1 to see the fibers. TG 101 is used for analyzing OAR cochlea, Brainstem, White fibers. Most of the patients given single dose of 13 Gy at 50% isodose line. Radiobiological effect was analyzed using review and formulated. Around 40% of our patient’s tumor size is stable after exposure and 75% of patients were grade 2 patients in the sample of 115 patients. So it is necessary to bring out perfect radiobiological mechanism. Hearing impairment was analyzed.

Results: for mask patients and 0.6mm for Frame based patients are needed at one sigma level since SRS for benign considering very strict margin level. Registration using MMI metric intercept shows -1.44, -1.66, -4.03 for 50, 100, 1000 bins respectively. Dose rate is not having much impact but the dose delivered above 8Gy is having the impact and creating SRS damage due to damage of vascular structure. Contralateral values of DTI parmeters FA(Fractional Anisotropy), Linear Measure were analyzed.
Conclusion: Metric test can be done for T1, T2 registration using slicer as reference to compare with other modality. DTI is important tool for checking the fibers around the tumor. Optimized hypo fractionation is needed for SRS without loosing surgical effect to enhance TCP.


Not Applicable / None Entered.


IM/TH- Image Registration: MRI

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