Transcript Stereotactic Radiosurgery
Stereotactic Radiosurgery
http://www.sdgkc.com/ http://www.sdgkc.com/ Jimmy Johannes Physics 335 – Spring 2004 Final Presentation
Outline
Case Study What is Stereotactic Radiosurgery?
Stereotactic Localization Radiosurgery Applications Different technologies Gamma Knife LINAC-based systems CyberKnife
Case Study
Imagine… You’re an undergrad at NU… As you approach Finals Week you acquire the following symptoms: Headaches Nausea Searle? Mono Evanston Northwestern Healthcare MRI
MRI Result:
http://splweb.bwh.harvard.edu:8000/pages/papers/kaus/radiology2001/5a.gif
Diagnosis and Treatment
Diagnosis: Benign Brain Tumor Treatment:?
Chemo/Immuno therapy Invasive brain surgery Non-invasive radiotherapy Non-invasive stereotactic radiosurgery
Diagnosis and Treatment
Diagnosis: Benign Brain Tumor Treatment:?
Chemo/Immuno therapy Blood Brain Barrier Invasive brain surgery Non-invasive radiotherapy Non-invasive stereotactic radiosurgery
Diagnosis and Treatment
Diagnosis: Benign Brain Tumor Treatment:?
Chemo/Immuno therapy Invasive brain surgery Blood Brain Barrier High Risk Non-invasive radiotherapy Non-invasive stereotactic radiosurgery
Diagnosis and Treatment
Diagnosis: Benign Brain Tumor Treatment:?
Chemo/Immuno therapy Blood Brain Barrier Invasive brain surgery High Risk Non-invasive radiotherapy Too Non-Specific Non-invasive stereotactic radiosurgery
Diagnosis and Treatment
Diagnosis: Benign Brain Tumor Treatment:?
Chemo/Immuno therapy Blood Brain Barrier Invasive brain surgery High Risk Non-invasive radiotherapy Too Non-Specific Non-invasive stereotactic radiosurgery
What is Stereotactic Radiosurgery?
Method to non-invasively & specifically treat benign/malignant tumors and tissue abnormalities Uses methods of stereotactic 3-D localization of surgical site Uses radiosurgical techniques to perform the “surgery”
3-D Stereotactic Localization
Goal: To target the tissue of interest with as much accuracy as possible Use imaging and 3-D mapping techniques to target tissue of interest 4 general medical imaging modalities used: X-Ray PET MRI Digital Subtracted Angiography Use the patient as a reference for the localization 2 general methods: Frame stereotactic localization (old school) Frameless stereotactic localization (new school)
The Imaging Modalities
Tomographic Techniques: PET (CT) and MRI Good for tumor pathologies Use multiple layers to get 3-D image X-ray-based Techniques: X-ray and Digital Subtracted Angiography Good for vascular imaging (for treatment of vascular malformations) Use pins and depth perception methods to get 3-D localization
Frame Techniques
With tomographic imaging modalities (CT and MRI), use the N-frame as a basis for 3 D visualization: N-Frame CT Gibson D, et al. Stereotactic Localization in Medical Imaging: A Technical and Methodological Review. Journal of Radiosurgery, Vol 2, No. 3, 1999 MRI
Frame Techniques
With X-ray imaging modalities: Schematic Angiography (X-ray) Schematic of basis for 3-D imaging
Frameless Stereotaxy
Implanted Gold Markers Amorphous silicon detectors (CyberKnife)
Display of treatment planning:
http://virtualtrials.com/jhrs.cfm
Radiosurgery
http://neurosurgery.medsch.ucla.edu/programs/radios urgery/radiosurgery_intro.html
Focused radiation beams delivered to a specific tissue volume Multiple beams or multiple passes (fractionated treatment) that intersect Keeps radiation exposure to surrounding tissue at benign levels Treats targeted tissue (the point of intersection) with a higher dose of radiation
How does it work?
How is it therapeutic?
Radiation does not remove the tumor or tissue abnormality For tumors, radiation distorts DNA (ionizing radiation induces mutations and other forms of DNA damage) High incidence of DNA damage and ionization induces cell cycle arrest (cells stop growing and replicating) and causes the cell to lose its ability to retain water Tumor reduction happens at the rate of the normal growth rate of that tumor For arteriovenous malformations (tangle of blood vessels), radiation induces the thickening and closing off of the blood vessel
How does it work?
Benign tumors take up to 2 years to disappear Metastatic (Cancerous) tumors (with a much faster growth rate) take only months to disappear
Side Effects
Swelling: cells lose ability to retain fluid, edema may occur Necrosis: dead tumor cells may cause complications (inflammation, fibrosis) Psychological side effects: loss of memory, decreased cognitive abilities, etc. (you are taking out a chunk of brain!)
Radiation-induced tumor/cancer:
radiation-induced mutations may result in a new tumor or cancer
Applications
Mostly used for brain surgery It’s where other more invasive procedures are deemed too risky Machines are designed mostly for brain surgeries Frame stereotaxy only allows for brain surgery But new machines and stereotaxy techniques are allowing for application in other parts of the body Mostly used for tumors and vascular malformations But new therapeutic applications have been developed for other tissue diseases and functional disorders
Types of Radiation
Differs with different machines: High-energy X-ray From linear accelerator systems Gamma radation From Cobalt-60 source Proton From particle beam or cyclotron Limited use in the US Uses Bragg Peak principle: As proton slows down, it gives off disproportionately more energy Right before it stops, it gives off most of its energy, resulting in a peak at that depth of tissue
Different Machines in Use
Gamma Knife Gamma radiation from Cobalt-60 Source Use multiple beams to treat tissue volume LINAC-based systems (X-Knife) High-energy X-ray from Linear Accelerator device Use fractionation CyberKnife Also a LINAC system, but LINAC is on a robotic arm Use fractionation Can be used for parts of body other than the head
http://www.elekta.com/ContentUS.
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Gamma Knife
-Over 30 years of clinical use and a great deal of publications -Targeting Precision of within 2mm -Multiple targets can be easily treated in one session
LINAC-Based Systems
-Less accurate -In use in more hospitals -Less efficient (longer treatment times)
http://www.radionics.com/resources/patient/xknife_description.s
html
CyberKnife
-Can treat most regions of body -w/ Stereotactic frame, can approach accuracy of LINAC or GammaKnife -Real-time frameless stereotaxy can be used