Years of Clinical Experience

1. Overview of Gamma Knife® SurgeryDr. Sandra Vermeulen, M.D.Swedish Cancer InstituteNorthwest Hospital Gamma Knife CenterSeattle, WashingtonLearn more at:www.DoctorVermeulen.com

2. Years of Clinical Experience 1968The first prototype of Leksell Gamma Knife® was installed in Stockholm, Sweden. 1999Elekta introduces the Leksell Gamma Knife® C.

3. Leksell Gamma Knife® C

4. The delivery of a single, high dose of irradiation to a small and critically located intracranial volume through the intact skull. 201 beams intersecting in one focal point Gamma Knife® Surgery

5. Automatic Positioning System Cobalt-60 sources Beam Channel Helmet with Collimators Shielding Helmet Supports Plastic Cover Treatment Couch with Mattress Protection Panels Shielding Doors Helmet in Treatment Position Leksell Gamma Knife® C

6. The Treatment Procedure 3. Treatment Planning 1. Frame Fixation Á ¾ 2. Diagnostic Imaging 4. Treatment

7. 1. Frame Fixation • Patient Fixation • Establish Spatial References

8. 2. Diagnostic Imaging • The coordinate frame provides stereotactic localization • Digital image transfers to the treatment planning computer

9. 3. Treatment Planning Team Approach: • The target is defined by the Radiation Oncologist, Neurosurgeon and Medical Physicist. • Care is taken to avoid critical areas of the brain while maximizing the dose to the target.

10. 4. Treatment • Automatic treatment, supervised by redundant safety and verification systems • Patient communicates via audio visual system

11. Open Surgery Daysin ICU Weeks of Hospitalization Several Weeks Convalescence Symptom Diagnosis Gamma Knife® Surgery The Time Factor

12. Clinical Outcome • Peer reviewed scientific articles shows better or equal results compared with microsurgery • Reproducible results • Fewer complications • Treatment solution for inoperable patients • Combined treatment with microsurgery and endovasculartechniques extend the capabilities

13. Examples of Treated Indications Functional Targets - Trigeminal nerve Vascular - Arteriovenous malformations Tumors - Meningioma - Pituitary - Acoustic Neuroma - Metastatic - Gliomas Research Areas - Intractable pain targets - Parkinsonian targets - Psychonuerosis targets - Epilepsy targets - Other functional targets

14. Arteriovenous Malformation Pre-Gamma Knife Surgery 2 Years Post Gamma Knife® Surgery Courtesy: Douglas Kondziolka, MD, MSc, FRCS, University of Pittsburgh, USA

15. Arteriovenous Malformation • Untreated lesions have a 2-4% risk of bleed per year. • After Radiosurgery, the risk of bleed remains unchanged until the AVM occludes. • 80% of lesions treated with Radiosurgery-occlude within 1-3 years following treatment. • A-V’s amendable to surgery should be resected

16. Acoustic Neuroma Courtesy: Douglas Kondziolka, MD, MSc, FRCS, University of Pittsburgh, USA Pre-Treatment 6 Months Post Treatment 2 Years Post Treatment Note: These pictures are provided for education purposes only. Elekta makes no claims as to the effectiveness of the Leksell Gamma Knife ® in these treatments.

17. Acoustic Neuroma • 90% show no further growth after treatment at 10 years. • Tumors that grow slowly respond slowly to Radiosurgery. • Larger tumors greater than 3.0cm should be surgically removed if they are causing acute symptoms from brainstem compression.

18. Pituitary Adenoma Courtesy: Ladislau Steiner, MD, PhD, UVA Charlottesville, USA, and Christer Lindquist, MD, PhD, Karolinska Institute, Sweden Pre-Treatment 54 Months Post Treatment Note: These pictures are provided for education purposes only. Elekta makes no claims as to the effectiveness of the Leksell Gamma Knife ® in these treatments.

19. Pituitary Adenoma • Tumors compressing the optic chiasm are not appropriate targets for Radiosurgery. • The optic chiasm maximum safe dose tolerance in a single fraction is less than 10 Gy. • The dose necessary to control a Pituitary Adenoma is in excess of 10 Gy.

20. Metastasis Courtesy: Douglas Kondziolka, MD, MSc, FRCS, University of Pittsburgh, USA Pre-Treatment 2 Months Post Treatment Note: These pictures are provided for education purposes only. Elekta makes no claims as to the effectiveness of the Leksell Gamma Knife ® in these treatments.

21. Metastasis • Appropriate Lesions for Radiosurgery are: • Tumors less than 3cm • Those not associated with a life-threatening mass effect • 4 or less tumors simultaneously presenting in the brain with or without whole brain irradiation

22. Astrocytoma Courtesy: Ladislau Stenier MD, PhD, Christer Lindquist, MD, PhD and Dheerendra Prasad MD, UVA Charlottesville, USA Pre-Treatment 5 Years Post Treatment The tumors pattern of spread results in high radiosurgical treatment failures. Note: These pictures are provided for education purposes only. Elekta makes no claims as to the effectiveness of the Leksell Gamma Knife ® in these treatments.

23. A Globally Embraced Treatment 202 Leksell Gamma Knife®Installed WorldwideMay 2004

24. Gamma Knife® SurgeryCumulative Number of Patients Treated

25. Quality of Life • Non-Invasive • Less trauma • Faster recovery • Minimal hospitalization • Fewer complications • Documented Efficacy