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PortalVision aS1000 The state of the art in electronic ... Flipbook PDF
PortalVision aS1000 The state of the art in electronic portal imaging USA Headquarters, California Varian Medical System
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PortalVision aS1000 The state of the art in electronic portal imaging The PortalVision™ aS1000 MV imaging system achieves the highest levels of performance in low dose imaging, image quality, reliability, and convenience. Based on Varian’s Amorphous Silicon (aSi) detector technology, the PortalVision aS1000 is the most advanced high-resolution electronic portal imaging device available. PortalVision aS1000 is also a standard component of the Trilogy™ system — the most advanced radiation therapy system from Varian. Electronic portal imaging
The PortalVision aS1000 imager allows patient position verification before treatment delivery, verification of treatment field size and shape, and rapid acquisition of portal dose images for Portal Dosimetry QA. It provides precise, welldefined megavoltage (MV) images of radiopaque markers for positioning soft tissues in the treatment beam, which enables precise patient positioning for Intensity Modulated Radiation Therapy (IMRT). The power and versatility of PortalVision aS1000 are essential for high precision IMRT and Dynamic Targeting™ Image-Guided Radiotherapy (IGRT). Third generation Varian Amorphous Silicon detector technology
The PortalVision aS1000 third generation flat panel detector is a solid-state matrix of 1024 x 768 pixels, and Varian’s extensive experience with this technology platform has proven its exceptional radiation hardness and detector lifetime. The panel’s spatial resolution will not change over time and its image quality is equal to or superior to film. 1 MU portal image acquisition: a Varian exclusive
A completely new design, the IAS3 Image Acquisition System in PortalVision aS1000 coordinates readout of the image receptor with irradiation by the accelerator, enabling high quality image acquisition with radiation doses as small as
1 monitor unit (MU). IAS3 also enables the acquisition of gated MV radiographs, when combined with the Real-Time Position Management (RPM™) respiratory gating system. Portal dosimetry/IMRT QA: highest dose rates without saturation
While IMRT has greatly improved radiation therapy, it has also placed a heavier burden on physicists to verify that treatments are delivered as planned. Used in conjunction with the optional Portal Dosimetry tool, PortalVision aS1000 reduces the physicist’s workload. All IMRT fields of a patient’s treatment can be delivered with the PortalVision aS1000 imager in the beam – without the patient present. Using a special imaging mode, the entire treatment can be integrated by the PortalVision aS1000 to yield a single, integrated image of the IMRT field. By comparing each field to a predicted portal dose image, the user can determine, quantitatively, whether the delivered treatment matches the planned treatment. PortalVision aS1000 can easily be positioned near the isocenter to increase the measured field size. The exceptional image acquisition rate (up to an industryleading 30 frames/sec) of PortalVision aS1000 enables it to handle all dose rates (up to an unprecedented 600 MU) without saturation, so Portal Dosimetry can be performed for a wider variety of treatments, and reducing the time for IMRT QA measurements from 2-4 hours to as little as 15 minutes.
PortalVision aS1000 The state of the art in electronic portal imaging
AP thorax, AP pelvis, and lateral pelvis images.
Highest resolution images, flexible file size
Efficient online review
By blending high resolution with very small file size, PortalVision aS1000 delivers truly unmatched image quality. Each pixel in the detector comprises a photodiode to integrate the incoming light as charge captures, and a thin film transistor switch for readout, reducing noise and improving image quality. The 14-bit image digitization feature dramatically expands dynamic range and enhances contrast resolution. When soft-tissue surrogates (radiopaque markers) are used to assess positioning, the PortalVision aS1000 can resolve 1 mm diameter gold cylinders using radiation doses as low as 1 MU.
When used with the 4D Integrated Treatment Console the PortalVision aS1000 provides a convenient way of acquiring high quality images — using low radiation doses — and correcting the patient position before treatment delivery. The reference images for all fields are automatically loaded with the plan and can be compared quantitatively with the portal images from the PortalVision aS1000. Once any patient corrections are measured the couch position can be adjusted.
3-axis positioning, highest range of motion in the industry
Moved into place by the industry-leading, robotic 3-axis Exact™ arm, PortalVision aS1000 offers complete flexibility in imager positioning. Whether used for a lateral setup, image verification of a field that requires couch rotation, or for measuring IMRT QA readings with the imager at the isocenter, the PortalVision aS1000 can be precisely positioned. Using Remote Arm Motion (available when PortalVision is installed along with the On-Board Imager® kV imaging system), the imager can be positioned or parked without entering the treatment room, allowing faster, more convenient procedures. Seamless integration
Key to the value of the PortalVision aS1000 is its integration with the 4D Integrated Treatment Console and the ARIA™ or VARiS Vision™ oncology information system. It seamlessly integrates with all Varian applications used for virtual simulation, treatment planning, plan verification, treatment delivery and remote image review and management.
Comprehensive offline review
PortalVision aS1000 images are automatically saved to the ARIA or VARiS Vision oncology information system or standalone PortalVision system, so physicians can review and approve the portal images at any location within the department. Tools are also available to automatically register the portal and the reference images, and patient notes can be used to communicate any changes in the treatment plan to the therapists. With PortalVision aS1000, the physician can easily monitor and supervise treatment at all times. Easy upgrades
Operation of the PortalVision aS1000 is very similar to earlier generations of PortalVision, making it easy for existing PortalVision users to integrate the capabilities of this new high-performance technology to their clinical routine. Building upon Varian’s many years of experience with the acclaimed PortalVision aS500, the new PortalVision aS1000 sets new standards for low dose imaging, image quality, reliability and convenience. The most advanced electronic portal imaging device available
Truly the state of the art in electronic portal imaging, PortalVision aS1000 is a standard component of the Trilogy system — the most advanced radiation therapy system from Varian.
Specifications 1.0
2.5 Typical Exposure: 2-3 MU 2.6 Minimum Exposure: 1 MU (low dose mode) 2.7 Maximum Exposure: 999 (IMRT/Integration mode)
Image Detection Unit: Amorphous Silicon (aSi) flat panel imager
1.1 Active Imaging Area: 30 x 40 cm2 1.2 Field of View at Isocenter: • For Imaging: 25 x 33 cm2 (120 cm SID) to 16 x 22 cm2 (180 cm SID) • For Portal Dosimetry: 30.8 x 41 cm2 (97.5 cm SID) to 16 x 22 cm2 (180 cm SID) 1.3 Pixel Matrix: Selectable: 1024 x 768 or 512 x 384 1.4 Pixel Pitch: 0.392 mm or 0.784 mm 1.5 Minimum Image Dose: 1 MU using low dose image acquisition mode 1.6 Energy Range: 4 - 25 MV 1.7 Supported Dose Rates: • For Imaging: 50 - 600 MU/min • For Portal Dosimetry: 50 MU/min – 600 MU/min (100 cm SID) 1.8 Housing: Standard PortalVision image detector housing, retrofitable on existing Exact™ arms and R arms 1.9 Weight: 10 kg 1.10 Radiation Hardness: aSi based portal imaging systems supplied by Varian or Varian Medical Systems have been in routine clinical operation since 1998. During this time, the detectors have proven excellent reliability and stability and have not shown additional significant deterioration in image quality. Using the system under standard clinical conditions1, the detector (panel and surrounding electronics ) lifetime is expected to be ≥ 4 years. 1 Definition of standard clinical conditions: working week with approximately 150 treatment fields with electronic portal imaging, 75% of fields