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A typical linac of today
3
Varian Clinac
®
Engineered for Clinical Benefits
1 Gridded Electron Gun
Controlsdose rate rapidly and accurately.Permits precise
beam control for dynamic treatments, since gun can be gated.
Removable for cost-effective replacement.
2 Energy Switch
Patented switch provides energies within
the full therapeutic range,at consistently high, stable dose rates,
even with low energy x-ray beams. Ensures
optimum performance and spectral purity at both energies.
3 Wave Guide
High efficiency,side coupled standingwave accelerator guide
with demountable electron gun and energy switch.
4 Achromatic 3-Field Bending Magnet
Unique design with fixed ± 3 %energy slits ensures exact
replication of the input beam for every treatment.
The 270
o
bendingsystem, coupled withVarian’s3-dimensional
servo system, provides for a2 mm circular focal spot size
for optimal portal imaging.
5 Real-Time Beam Control Steering System
Radial and transverse steeringcoils and a real-time feedback system
ensure that beam symmetry iswithin ± 2 %at all gantr y angles.
6 Focal Spot Size
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8
9
10
Utrecht 2016
Even at maximum dose rate – and any gantry angle – the circular
focal spot remains less than 2 mm, held constant by a focus solenoid.
Assuresoptimum image quality for portal imaging.
7 10-Port Carousel
New electron scattering foils provide homogeneous electron beams
at therapeutic depths. Extraports allow for future development
of specialized beams.
8 Ion Chamber
Dual sealed ion chambers with 8 sectors for rigourousbeam control
provide two independent channels, impervious to changes
in temperature and pressure.Beam dosimetry is monitored to be
within ± 2 %for longterm consistency and stability.
9 Asymmetric Jaws
Four independent collimatorsprovide flexible beam definition
of symmetric and asymmetric fields.
10 Millennium
™
Multi-Leaf Collimator
Dynamic full field high resolution 120 leaf MLC with
dual redundant safety readout for most accurate conformal beam
shapingand IMRT treatments.
11 Electronic Portal Imager
High-resolution PortalVision
™
aS1000 Megavoltage imager mounted on a
robotic arm for efficient patient setup verification and IMRT plan QA.
12 On-Board Imager
®
kV X-ray source (12a) and high-speed, high-resolution X-ray detector (12b)
mounted on two robotic arms orthogonal to the treatment beam for
Image Guided Radio Therapy (IGRT).The unique system provides kV imaging
at treatment and includes radiographic,fluoroscopic and Cone Beam CT
image acquisition and patient repositioningapplications.
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12a
12b