Download PortalVision aS1000 The state of the art in electronic portal imaging

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 <12 x 12 cm2, 250 cGy/week or
130 Gy/year on the surrounding electronics.
1.11 Compatibility with: Clinac®, Clinac iX,
Trilogy™ System, 4D Treatment Console
2.0
3.0
3.1 Contrast Resolution: 0.2% for 6 MV beam (for
0.8 MU/frame; 10 frame average; contrast
defined as the difference divided by the sum of
the transmissions)
3.2 Small Object Detection: 0.5 mm diameter
(lead, tungsten, or tantalum) wire can be
detected (wire placed diagonally, wire at
isocenter, image detection unit at 140 cm SID)
3.3 Spatial Resolution: No Varian Medical Systems
specification; customer measurements of f50:
0.50 mm-1 (for phantom at isocenter and
image detection unit at 150 cm SID, high
resolution mode)
4.0
Support Arms
4.1 Exact arm robotic detector support for:
• High energy Clinac 2100 with S/N 1167
and above
• High energy Clinac 2300 with S/N 197
and above
• All Silhouette high energy Clinacs
4.2 R arm robotic detector support for:
• All low energy Clinacs
• High energy Clinac 2100 with S/N 1166
and below
• High energy Clinac 2300 with S/N 196
and below
5.0
Exact Arm Motions
5.1 Lateral Movement: ±16 cm
5.2 Longitudinal Movement: 40 cm range
(at 130 cm SID)
5.3 Vertical Movement: 182 cm – 97.5 cm SID
(with lateral and longitudinal settings of
0.0, 0.0)
5.4 Vertical Orientation Accuracy: A lateral or
longitudinal displacement of less than ±2 mm
with a vertical motion from 0 cm to 60 cm
SID
5.5 Positioning Reproducibility: Within a 2 mm
diameter for each axis (vertical, longitudinal,
lateral)
5.6 Extension/Retraction Time: 9 -10 seconds
(From retract position to 140 SID)
Image Acquisition
2.1 Digitization: 14-bit image
2.2 Image Acquisition Rate: Up to 30
frames/second depending on Clinac dose rate
and pixel matrix
2.3 Acquisition Modes:
• Standard (detector readout during MV
beam on)
• Low Dose (detector readout while MV beam
is paused)
• Integration or IMRT (for Portal Dosimetry)
2.4 Acquisition Time: 1-3 seconds from beam on
to image display
Image Performance
6.0
R Arm Motions
6.1 Lateral Movement: 31 cm range
6.2 Longitudinal Movement: 31 cm range
(at 140 cm SID)
PortalVision aS1000 The state of the art in electronic portal imaging
6.3 Vertical Movement: 180 cm – 105 cm SID
(with lateral and longitudinal settings of
0.0, 0.0)
6.4 Positioning Reproducibility: Within a 8 mm
diameter for each axis (vertical, longitudinal,
lateral)
6.5 Extension/Retraction Time: 10 - 12 seconds
(From retract position to 140 SID)
7.0
10.0 Portal Dosimetry Review Workspace
10.1 Automatic and manual alignment of the
reference versus measured image
10.2 Absolute and relative dose matrices comparison
10.3 Point dose and line profile analysis
10.4 Dose difference matrix display
10.5 Gamma evaluation matrix display
10.6 Statistical analysis of the gamma evaluation
Acquisition Workspace
Flexible image acquisition supports the following
acquisition modes:
8.1 Single exposure image
8.2 Double exposure image with plan field outlined
automatically
8.3 IMRT grayscale with automatic image dose
integration
8.4 Auto setup option for image detector positions
for patient-specific or field-specific image
acquisition
8.5 Auto optimization of image detector position
within beam, to minimize radiation exposure to
support electronics
8.6 Auto beam off option after the image
acquisition by aS500-II to minimize
unnecessary patient dose
8.7 Visualization of reference image with
supporting overlays
Image Review Workspace
9.1 Supports the review process of portal images in
the control room with tools such as optimally
viewing, online matching, and annotation of
images within seconds of acquisition.
9.2 Portal images are quickly available for offline
review with quantitative image analysis
(automatic matching) with comprehensive
functions for the evaluation of the results and
image approval by the oncologist with entry of
patient notes, e.g., for patient positioning,
which will be displayed prior to the next image
acquisition or when scheduled to appear.
Application Software
7.1 Easy-to-use and intuitive Windows®-based user
interface
7.2 Similar operation and user interface as in prior
PortalVision workstations or 4D Integrated
Treatment Consoles
7.3 Full network integration with all ARIA or
VARiS Vision applications
7.4 Online matching and image evaluation by
means of all standard ARIA or VARiS Vision
image-processing functions
7.5 Imager maintenance and calibration utilities
8.0
9.0
11.0
Maintenance Workspace
11.1 System maintenance and tuning
12.0 Calibration Workspace
12.1 Calibration of the used image acquisition
modes by acquiring dark field and flood field
images, with automatic generation of pixel
defect correction map
12.2 Flood field calibration at a single dose rate
completes calibration for all dose rates at that
energy
12.3 Dosimetric calibration of the imager in absolute
mode permits portal dose quantification
13.0 Printing
13.1 Print Quality: Dependent on printer and
Windows drivers. Images are saved in 14/16 bit
format while printers (e.g., Codonics
NP1660M; Kodak 3600) typically print 256
gray levels.
Specifications subject to change without notice.
All other company and product names mentioned herein are used for identification purposes only and may be trademarks or
registered trademarks of their respective owners.
USA Headquarters, California
Varian Medical Systems
Palo Alto, CA
Tel: 650.424.5700
800.544.4636
Fax: 650.493.5637
www.varian.com
RAD 2553B
Headquarters Europe, Eastern Europe, Africa,
Middle & Near East
Varian Medical Systems International AG
Zug, Switzerland
Tel: 41.41.749.8844
Fax: 41.41.740.3340
[email protected]
© 2006 Varian Medical Systems, Inc. Printed in USA
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