SRS/SRT Treatment Planning for Skull Base Meningioma

Transcription

1 SRS/SRT Treatment Planning for Skull Base Meningioma Janne Heikkilä, Medical Physicist, PhD Centre of Oncology, Kuopio University Hospital, Kuopio, Finland

2 CyberKnife In General Designed for frameless stereotactic radiotherapy Image-guided dose delivery using 2D orthogonal positioning images (imaging interval s) Image-guided based on fiducial markers, lung tumors, or bone structures (skull or spine) Typical treatment delivery time is min

3 CyberKnife Beam geometry 130 pre-defined nodes (possible locations for linac) are on the spherical surface centered with the origin of the imaging system 12 beams can be delivered from each node to the target

4 CyberKnife Treatment delivery Multiple beams from one node Beams from the same node Imaging origin Beams Eye View, BEV Beams Eye View, BEV

5 CyberKnife Collimators InCise Multileaf Collimator Fixed Collimator 100 x 100 SAD=800 mm Iris Collimator 5 60 SAD=800 mm 5 60 SAD=800 mm

6 Target tracking during the treatment 6D Skull Corrections are calculated and applied automatically to the linac robot position Imaging interval can be adjusted to be s

7 Image-guided frameless treatment delivery

8 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning

9 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning CT: 1 mm slices Thermoplastic mask

10 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning CT: 1 mm slices Thermoplastic mask MRI (1.5T): T1 (FSPGR) T2 (SE) FIESTA-C (GE) 3D Sag T1 FSPGR (GD) 3D Sag T2 (GD) 3D Ax Fiesta-c T2 (GD)

11 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning CT: 1 mm slices Thermoplastic mask MRI (1.5T): T1 (FSPGR) T2 (SE) FIESTA-C (GE) Other modalities: PET 3D DSA

12 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning CT: 1 mm slices Thermoplastic mask MRI (1.5T): T1 (FSPGR) T2 (SE) FIESTA-C (GE) Other modalities: PET 3D DSA DTI Tractography

13 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning CT: 1mm slices Thermoplastic mask MRI (1.5T): T1 (FSPGR) T2 (SE) FIESTA-C (GE) Other modalities: PET 3D DSA DTI Tractography NBS (Navigated Brain Stimulation) -> Motor cortex

14 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning

15 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning MIM Software (v ) CT+Multiple MRIs can be shown on the same layout Same structure can be contoured on all images and 3 views Structures and registrations are exported to Multiplan Multiplan workstations are dedicated for treatment planning and plan approval

16 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning

17 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning Template based Sequential optimization

18 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning Template based Sequential optimization MU limits 5x6 Gy

19 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning Template based Sequential optimization MU limits Shells (3, ~10, ~20 mm)

20 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning Template based Sequential optimization MU limits Shells (3, ~10, ~20 mm) Iris or Fixed collimators Fixed:1 2(3) collimators Iris: 3 or more

21 Radiotherapy process in Kuopio Pre-treatment imaging Fusions and contouring Treatment planning Template based Sequential optimization MU limits Shells (3, ~10, ~20 mm) Iris or Fixed collimators Fixed:1 2(3) collimators Iris: 3 or more Full path Normalization 75 80% Ray-Tracing calculation Minimum of 2 3 MU/Beam/Fraction Delivery time less than 60 min

22 Dose constrains for critical organs 1 fraction 5 fractions Structure Volume (cc) Total Dose (Gy) Max Point Dose (Gy) Comment Structure Volume (cc) Total Dose (cgy) Max Point Dose (cgy) Comment Optic Pathway Brainstem Cochlea Hearing loss Retina Skin Hippocampus As low as possible Optic Pathway Brainstem Cochlea Hearing loss Retina Skin Hippocampus As low as possible Brain tissue No beams through eyes Constrains we use are mostly from Grimm et al. (2011)

23 Clinical Cases

24 Case 1: Small tumor, 1x15 Gy 15 Gy 10 Gy 15 Gy 10 Gy Tumor volume: 4.5 ml Fixed collimator: 10 mm Treatment time: 40 min Normalization: 75% 152 beams from 36 nodes

25 Case 1: Small tumor, 1x15 Gy Tumor volume: 4.5 ml Fixed collimator: 10 mm Treatment time: 40 min Normalization: 75% 152 beams from 36 nodes 15 Gy 12 Gy 10 Gy 7.5 Gy 15 Gy 12 Gy 10 Gy 7.5 Gy Gradient: Dose from 15 Gy to 7.5 Gy in 3-4 mm

26 Case 2: Small tumor, 5x6 Gy Tumor volume: 10.3 ml Fixed collimators: 5, 10, and 15 mm Treatment time: 65 min Normalization: 80% 296 beams from 72 nodes 30 Gy 25 Gy

27 Case 2: Small tumor, 5x6 Gy Tumor volume: 10.3 ml Fixed collimators: 5, 10, and 15 mm Treatment time: 65 min Normalization: 80% 296 beams from 72 nodes 30 Gy 25 Gy 20 Gy 15 Gy 10 Gy Gradient: Dose from 30 Gy to 15 Gy in 5-6 mm

28 Case 3: Large tumor, 5x6 Gy Tumor volume: 88.4 ml Iris collimators: mm Treatment time: 55 min Normalization: 82% 376 beams from 111 nodes Gradient: Dose from 30 Gy to 15 Gy in 5-6 mm 30 Gy 25 Gy 20 Gy 15 Gy

29 Case 4: Large tumor, 5x6 Gy Tumor volume: 72.1 ml Iris collimators: mm Treatment time: 44 min Normalization: 79% 259 beams from 109 nodes 30 Gy 25 Gy 20 Gy 15 Gy

30 Thank you! KUH Centre of Oncology Medical Physicists: Jan Seppälä Jan-Erik Palmgren Janne Heikkilä Tuomas Viren KUH NeuroCenter Neurosurgeons: Juha E Jääskeläinen Olli-Pekka Kämäräinen Mikael von und zu Fraunberg