Trilogy TX Specification - Behestan Darman

1.2 Dose Rate: For Beams I and II, the dose rate can
be selected in fixed steps of 100 MU/min up to a
maximum dose rate of 600 MU/min. For the
SRS 6 MV Beam, the dose rate is 1,000
MU/minute. The SRS high dose rate supports
efficient delivery of stereotactic radiosurgery,
stereotactic radiotherapy, and intensitymodulated
radiation therapy (IMRT). Refer to
section 12.0 for further information.
Photon Energy (BJR17) Photon Dose Rate (MU/min)
6-25 MV 100, 200, 300, 400, 500, 600
SRS 6 MV 1000
An “MU” is defined for these specifications as one cGy delivered
to a tissue-equivalent material at Dmax and 100 cm SSD, with a
10 x 10 cm 2 field size.
1.3 Maximum Field Intensity at Dmax: The
intensity at the depth of maximum buildup
(Dmax) does not exceed 109% of the central
axis intensity anywhere in the measurement
plane of any field size.
1.4 Leakage: The X-ray absorbed dose does not
exceed 0.1% of the absorbed dose at the
isocenter measured anywhere in the patient
plane outside of the maximum useful beam.
The neutron dose equivalent (Sievert) does not
exceed 0.2% of the X-ray absorbed dose
(Gray) at the isocenter.
The patient plane is defined as a circular plane
with a radius of 2 m, centered on and
perpendicular to the axis of the beam at
isocenter. The X-ray measurements may be
averaged over an area not to exceed 100 cm2 .
In all other directions, the X-ray absorbed dose
at 1 m from the path of the electrons between
the electron gun and the target or electron
window does not exceed 0.1% of the absorbed
dose at isocenter.
1.5 Collimator Transmission: The X-ray transmission
of the upper and lower movable collimator does
not exceed 0.5%.
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1.6 Spot Size: The electron spot size is less than
3 mm in diameter at the X-ray target.
1.7 Penumbra: The distance between the 20% and
80% isodose lines for a 10 x 10 cm2 field,
measured at a depth of 10 cm with a 100 cm
TSD along the major axes, measures less than or
equal to 9 mm.
1.8 Field Size: The field size is continuously variable
from 0.5 x 0.5 cm2 to 40 x 40 cm2 as measured
at 100 cm TSD. Field sizes larger than 35 x
35 cm2 are limited to a 49.5 cm diagonal (the
diameter of the circle defined by the primary
collimator at 100 cm TSD). The field size is
defined as the distance along the radial and
transverse axes between the points of 50%
density on an X-ray film taken at 100 cm TSD
with minimum buildup. The SRS 6 MV beam
field size is limited to a maximum of
15 x 15 cm2 .
1.9 Upper and Lower Independent Collimators:
Asymmetrical collimation is provided for upper
and lower sets of collimators.
1.9.1 Independent, asymmetrical Upper
Collimator travel range: 30 cm (-10 cm
to +20 cm relative to central axis)
1.9.2 Independent, asymmetrical Lower
Collimator travel range: 22 cm (-2 cm to
+20 cm relative to central axis)
2.0 Electron Beams Option
2.1 Trilogy Tx offers a range of six (6) optional
electron beams that can be selected in accordance
with the specifications and combinations listed in
Table 2. The specifications apply to a 15 x 15
cm2 electron applicator and 100 cm TSD.
2.2 Dose Rate:
Electron Dose Rate (MU/min)
100, 200, 300, 400, 500, 600, 1000
888 at 1.6 m (choose either 6 MeV or 9 MeV)
A high electron dose rate is available at 6 MeV or 9 MeV electron
energy. Refer to section 8.1 for further information.
Varian Trilogy Tx specifications