Varian _ Dynamic Targeting TM Image-Guided Radiation Therapy Scott Johnson, PhD Varian Medical Systems Palo Alto, California Varian _

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  • Varian _ Dynamic Targeting TM Image-Guided Radiation Therapy Scott Johnson, PhD Varian Medical Systems Palo Alto, California Varian _
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  • VARIAN medical systemsPage 2 Varian IGRT Statistics As of the end of Dec, Varian had booked 80 orders for the On-Board Imager (OBI) As to today, 35 installations have been completed And another dozen installations currently are in progress As of today, cone-beam CT software has been installed at 7 sites Aarau, Switzerland Karolinska, Sweden MSKCC, New York Emory, Atlanta Stanford, Palo Alto Duke, Durham Henry Ford, Detroit With an additional installations scheduled in the very near future MD Anderson, Houston
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  • VARIAN medical systemsPage 3 What is IGRT? IGRT means several things Use of images for online setup correction, before treatment begins Position patient on table. Align the patient to lasers. Acquire images Images usually are kV Images may be an orthogonal pair of radiographs or a volumetric image (e.g., cone-beam CT) Compare the acquire images to reference images Analysis may be automated and/or manual Analysis may rely on radiopaque markers, bony anatomy or soft-tissue anatomy Result of the analysis is data on how to correct the patient position Move the treatment couch remotely to automatically correct the patient position Optional: Acquire and analyze another set of images to verify the correction Begin treatment delivery
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  • VARIAN medical systemsPage 4 Movie of the clinical process
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  • VARIAN medical systemsPage 5 What is IGRT? Use of images for online setup correction, before treatment begins Whats new here: Use of kV imaging in the treatment room New image analysis tools for the therapist Fast, easy to use, integrated into the existing workflow Remote couch control, to speed the process The result is: Significant improvement in target localization Reduced likelihood of missing the target An opportunity to reduce CTV-to-PTV margins and thus the volume of normal tissue irradiated to high dose May reduce the toxicity of RT
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  • VARIAN medical systemsPage 6 What is IGRT? IGRT also may mean adaptive radiation therapy Tumors, hopefully, respond to treatment and shrink over the course of therapy As the surrounding tissues are pulled inward, the result may increase the dose to critical structures With adaptive RT, goal is to use images to Perform online setup correction of patient position Acquire a volumetric image (cone beam CT scan) Automatically detect any changes in the target shape Automatically adapt the treatment plan to reflect the new target shape Provide the therapist with important information on how the plan has changed Deliver the new plan (Its kind of like a boost plan, but done online with the patient on the table) Above process should occur within 15-20 minutes, or less
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  • VARIAN medical systemsPage 7 What is IGRT? With adaptive radiation therapy, images of the tumor size, shape and location are used to adapt the treatment plan before it is delivered Critical structure Target Prescription isodose Original treatment plan and anatomy
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  • VARIAN medical systemsPage 8 What is IGRT? With adaptive radiation therapy, images of the tumor size, shape and location are used to adapt the treatment plan before it is delivered Critical structure Target Prescription isodose Original treatment plan and new anatomy with tumor shrinkage due to radiation
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  • VARIAN medical systemsPage 9 What is IGRT? With adaptive radiation therapy, images of the tumor size, shape and location are used to adapt the treatment plan before it is delivered Critical structure Target Prescription isodose Adapted treatment plan
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  • VARIAN medical systemsPage 10 What is IGRT? With adaptive radiation therapy, images of the tumor size, shape and location are used to adapt the treatment plan before it is delivered No one is doing this yet! Before it can be done, the following are needed Ability to acquire CT scans on the treatment table. DONE! Automated image segmentation tools that automatically contour the patient anatomy New treatment plan analysis tools for the therapist Including tools that clear show what treatment plan adaptations are needed and what the effect of those changes is Fast, easy to use software that is well integrated into the existing treatment delivery process Guidelines on when adapted treatment plans should be reviewed by a physicist or physician Guidelines on how to QA the adaptive radiation therapy process Etc
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  • VARIAN medical systemsPage 11 What is IGRT? IGRT also can be considered to include dose guided radiation therapy Acquire a CT scan of the patient on the treatment table in the treatment position Deliver the treatment plan Use an EPID to capture transit dose images or capture linac and MLC log files Use transit dose to back project delivered dose onto CT or use log files to forward project delivered dose onto CT The result is a realistic calculation of the dose delivered that day including the impact of bladder and rectal filling, bowel gas, etc Dose actually emitted by the linac overlayed onto CT scan of patient on treatment table
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  • VARIAN medical systemsPage 12 What is IGRT? IGRT also can be considered to include dose guided radiation therapy Now, imagine repeating the above process at each treatment session and having the ability to morph the results onto each other Summing the results allows you to visualize the dose actually delivered to the target and critical structures over a series of treatment sessions With advanced treatment planning tools, you then may choose to adapt the treatment plan mid-stream so that the final, cumulative dose satisfies the physicians prescription
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  • VARIAN medical systemsPage 13 What is IGRT? IGRT also can be considered to include dose guided radiation therapy Again, no one is doing this yet, but we are getting close Before it can be done, the following are needed Ability to acquire CT scans on the treatment table. DONE! Ability to capture linac and MLC log files or transit dose. DONE! Ability to project beams recorded in log files into CT scans. DONE! Image and dose morphing tools that allow you to sum the dose to a volume over several sessions, given that the volume is changing size, shape and location Fast, easy to use software that is well integrated into the existing treatment delivery process Guidelines on when to adapt a plan and when that adapted plan should be reviewed by a physicist or physician Guidelines on how to QA the dose guided radiation therapy process Etc
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  • VARIAN medical systemsPage 14 Will IGRT replace IMRT? No, the two are complementary. IMRT allows the dose to conform tightly to the PTV. IGRT allows the PTV to shrink to the CTV. IG-IMRT then allows simultaneously margin- reduction and dose conformation. Conventional RT IMRT IG-IMRT CTV PTV Organ at risk High dose isodose
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  • VARIAN medical systemsPage 15 Varian IGRT Technology On-Board Imager accessory Available as an upgrade to any Clinac installed in 1997 and after
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  • VARIAN medical systemsPage 16 On-Board Imager Hardware Two robotic arms kV Xray source Amorphous silicon imaging panel OBI workstation Three modes of operation Radiographic Online setup correction Bony anatomy or markers CBCT Online setup correction Bony or soft tissue anatomy Visualization of delivered dose Adaptive radiation therapy Fluoroscopic Verification of gated radiation therapy Fluoro-based tumor tracking (*Future option) Trilogy and the On-Board Imager
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  • VARIAN medical systemsPage 17 Command Center Clinac console, 4D Console, OBI workstation, RPM Gating workstation
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  • VARIAN medical systemsPage 18 Robotic arm motion
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  • VARIAN medical systemsPage 19 Robotic arm motion
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  • VARIAN medical systemsPage 20 Robotic arm motion
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  • VARIAN medical systemsPage 21 Robotic arm motion
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  • VARIAN medical systemsPage 22 Varian IGRT Technology Orthogonal radiographs for online patient setup correction
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  • VARIAN medical systemsPage 23 Acquisition of a lateral radiograph
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  • VARIAN medical systemsPage 24 Acquisition of an AP radiograph
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  • VARIAN medical systemsPage 25 Sample radiographs Images courtesy of Karolinska Medial Center
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  • VARIAN medical systemsPage 26 Sample radiographs Images courtesy of Karolinska Medial Center
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  • VARIAN medical systemsPage 27 On-Board Imager workstation
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  • VARIAN medical systemsPage 28 On-Board Imager workstation
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  • VARIAN medical systemsPage 29 Marker matching using the On-Board Imager
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  • VARIAN medical systemsPage 30 Marker matching using the On-Board Imager
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  • VARIAN medical systemsPage 31 Varian IGRT Technology Cone beam CT for online patient setup correction (and adaptive radiation therapy and dose guided radiation therapy)
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  • VARIAN medical systemsPage 32 Acquisition of a cone beam CT scan