ViewRay System Commissioning

Kyle R. Padgett, PhD, DABR Assistant Professor University of Miami Viewray Team: Matt Studenski, PhD Chet Ford, PhD Yidong Yang, PhD Nesrin Dogan, PhD Medical Physics Residents: Naru Lamichhane, PhD Xing Li, PhD

Disclosures

• None

2

Overview • Overview of the MRIdian system • Commissioning

– Safety – MRI – Mechanicals – RT System – Treatment Planning System – End to End Testing

Introduction • Commonly known as Viewray

MRIdian • Integrated magnetic

resonance (MR)-guided radiation therapy (RT) instrument designed to provide simultaneous MR Imaging (MRI) and a range of external beam RT options

• Consists of three major sub-systems – MRI System – RT System – Adaptive RT System

The MRI • Gapped horizontal solenoidal superconducting

magnet • 0.35 T whole body MRI, capable of volumetric and

real-time imaging • The MRI system consists of two separate magnets

abutted with a 28 cm gap. • Split gradient coil has an inner diameter of 80 cm. • Resolution as low as 0.75 mm • Planar “real-time” imaging at up to 4 frames per

second. • MR isocenter matched to RT isocenter • Body & Surface coils are thin & uniformly attenuating

The MRI • Split Super Conducting Magnet

• Allows Unobstructed Beam Path • Fits in Standard Vaults, Pop-apart

design for non-destructive rigging • 0.35T Field strength provides 50cm

DSV for large FOV imaging • Less image distortion and less

patient heating • Minimal distortion of dose

distribution • 70cm bore to accommodate large

patients • Split gradient with a 28cm gap, slew

200mT/m/ms, 18mT/m peak, 30kW heat removal.

Low Field MRI

• High-field causes a loss of spatial

integrity

• Magnetic susceptibility artifacts

due to the patient scales with

field strength

• High field distorts the dose

distribution

• Electron return effects get

worse with field strength

• High field heats the patient -SAR

Electron Return Effect • The Magnetic Field has an effect upon the

secondary electrons • The stronger the Magnetic Field the more

pronounced the effect

Raaijmakers et. al. Phys. Med. Biol. 53 (2008) 909–923

MRI Sequences Available • FISP - Fast Imaging with Steady Precession • GE – Gradient Echo (Only one small FOV option) • FISP is a coherent technique that uses a fully balanced

gradient waveform (true FISP) • The image contrast is determined by T2*/T1 and mostly

depends on the TR • The speed and relative motion insensitivity of acquisition

help to make the technique reliable.

• Other MRI sequences may become available on future software releases.

Setup Imaging

• All setup images shown use FISP imaging

• FOV ranges from 22 – 54cm

• Resolution ranges from 1.5 – 3.0mm

• Acquisition time ranges from 23 – 170sec

• GE setup image has a resolution of 7.5mm, a FOV of ~27cm and a acquisition time of 12min

Real Time Imaging / Gating

• All CINE images shown use FISP imaging • FOV ranges from 27cm to 45cm • Resolution ranges from 3.5mm to 10mm • All are 4 frames per second for a single slice

The RT delivery system • Equipped with three robotic

60Co treatment heads mounted with 120° separation on a rotating gantry.

• Each treatment head operates independently and they can be operated simultaneously.

• Each head can deliver up to 1.8Gy per minute at the machine isocenter, which is 105 cm from each source, with the nominal source strength of 15kCi. The source is shielded by a depleted-uranium safe in the retracted position

The RT delivery system • Rotating Gantry Assembly • 3 Independent Co60 Headed Design

• Enabling IMRT, SBRT or 3D-Conformal External Beam Radiation with Asynchronous Delivery

• Mounted with 120 degree separation

• 15,000 Ci per source • +- 240 degree Rotation for 2 or 3

Head Operation for increased Reliability.

• 3 Doubly Focused MLC Systems • 180 MLC Leaves. 60 per head • 1.05 leaf thickness projected at

isocenter

Source Operation

14

Beam Indicator

Beam Indicator

Beam OFF

Beam On

The MLC • 3 Doubly Focused MLC

Systems • 180 MLC Leaves Per Head • 1.05cm leaf thickness

projected at isocenter • Fully interdigitating • Average Leakage less than

0.375%

Adaptive RT System • An integrated high-performance radiation planning

and delivery software capable of auto contouring, Monte Carlo dose computation, and IMRT or conformal RT planning or both are used to support 3-dimensional conformal RT, IMRT, and on-couch ART.

• The speed of the TPS (9 field plans with complete optimization, leaf motion calculation, and dose calculations can be accomplished in less than 30 seconds) enables ART treatments based on the volumetric image of the day

Commissioning Equipment • Water tank with manually driven chamber holder • Non-magnetic ion chamber: Exradin Nonmagnetic

A28 & standard A12 chambers • MRI-compatible IMRT QA device: ArcCheck 1220-

MR, Sun Nuclear Corporation • MRI-compatible beam profiler: ArcCheck IC

Profiler 1122-mr, Sun Nuclear Corporation • Gafchromic Films and Film Processor • 2D Spatial Integrity Phantom • Spherical Water Phantoms • CIRS Gating Phantom • ACR MRI Phantom

Safety • Radiation shielding

survey was performed by the University of Miami radiation safety office. All points outside the treatment vault showed radiation levels in compliance with regulatory limits specified in 10 CFR, part 20 (limit of 2mR/hr)

Safety • Door Interlocks: Beam was successfully interrupted when door is opened

• Emergency stop buttons: The 5 emergency stop buttons were enabled and generated safety interlocks on the console

• Beam on Warning Light: Warning light successfully operated during irradiation

• Prime Alert Functionality: Prime alert functionality was confirmed with a check source

• Intercom and AV Monitoring: Confirmed with successful communication between two individuals

• Backup Timer: Primary timer was disabled and the backup timer successfully terminated the beam

• Emergency Door operation: Operates when power is off

• Emergency Couch Retract: Can be initiated manually and when power is off

• Many other safety interlocks were also tested during ATP

MRI Tests • Magnetic Field

Homogeneity • Phased Array Coil

Elements • Image Homogeneity • Spatial Integrity • High Contrast

Resolution

• Slice Thickness • Slice Position

Accuracy • Low Contrast

Resolution • Ghosting Ratio

Magnetic Field Homogeneity

Gantry 0 Gantry 30

Gantry 60

Gantry 90

Gantry 120

FWHM

<= 5ppm

1.53ppm 1.46ppm 1.44ppm 1.60ppm 1.74ppm

• The homogeneity of the MRI system was measured using a large spherical water phantom

• A water spectrum was then collected to determine the frequency spread at FWHM

• Repeated at several different Gantry Angles and with the different RF coils

Coil Element Tests

• The signal characteristics for the coil elements for all phased array coils were measured.

• 12 element Torso Coil • 12 element Head and Neck Coil

• All SNR measurements significantly exceeded specifications

• Shape of signal profile was also qualitatively evaluated.

Homogeneity • Homogeneity of the Body,

Torso, and H&N Coils were measured and exceeded specifications

• 60% Body Coil • 50% Torso Coil • 50% H&N Coil

• The Signal to Noise of the Body, Torso, and H&N Coils were measured and exceeded specifications

• SNR > 12 Body Coil • SNR > 30 Torso Coil • SNR > 30 H&N Coil

SNR = (ROI signal mean) * 0.66 / (ROI Noise SD) Uniformity % = 100 * 1 – [(ROI Signal max – ROI Signal min) / (ROI Signal max + ROI Signal min)]

Spatial Integrity

Pass-Rate 1mm Ring

Pass-Rate 2mm Ring

Max error

Axial 100.0% 100.0% 1.764mm Coronal 99.3% 98.7% 2.134mm Sagittal centered

100.0% 100.0% 1.298mm

Sagittal 12.5cm Patient Left

N/A 100.0% 1.387mm

Sagittal 12.5cm Patient Right

N/A 100.0% 1.060mm

• 2D spatial integrity was measured with a custom made phantom provided by Viewray

• All measurements within inner circle must have less than 1mm of distortion

• All measurements within outer circle must have less than 2mm of distortion

• This test is also performed in our Monthly QA

High Contrast Resolution

Figure 6: from ACR “Phantom Test Guidance for Use of the Small MRI Phantom”

• To assess the scanner’s ability to resolve small objects when the contrast to noise ratio is sufficiently high.

• Test utilizes the MRI ACR phantom • Should be able to visualize/resolve

several of the rows and columns of four. • This test is also performed in our

Monthly QA

Slice Thickness • To assess the accuracy with

which a slice of specified thickness is achieved

• Test utilizes the MRI ACR phantom

• Two signal ramps with a slope of 10 to 1 are utilized

• Thickness should be 5mm ± 0.7mm

• This test is also performed in our Monthly QA

Slice thickness = 0.2 x (top x bottom)/(top + bottom)

Slice Position Accuracy • To assess the accuracy with

which slices can be prescribed at specific locations

• Test utilizes the MRI ACR phantom

• Two crossed wedged ramps of 45 degrees are utilized

• The difference in the two bar length determines the slice position accuracy

• ½ of the measured length is the positional discrepancy

• This test is also performed in our Monthly QA

Low Contrast Resolution • To assess the extent to which

objects of low contrast are discernible in the images

• Test utilizes the MRI ACR phantom

• The low contrast disks are holes drilled in thin sheets of plastic mounted in the phantom

• Must find 9 spokes on 4 subsequent slices in both the T1 and T2 acquisitions

• This test is also performed in our Monthly QA

Ghosting Ratio • To assess the level of ghosting

in the images • Test utilizes the MRI ACR

phantom • ROIs are drawn inside the

phantom and in 4 surrounding areas to calculate the ghosting.

• Ratio must be less than 0.025 • This test is also performed in

our Monthly QA

Ghosting Ratio = [(top + btm) – (left + right)] / (2 x Large ROI)

Mechanicals • Couch Motions • Couch Level • Couch Sag • Couch orthogonal to

imaging plane • Laser / MRI

Coincidence

• Radiation / MRI Coincidence

• Radiation Isocentricity

• Gantry Angle Accuracy

Couch • Couch Motions • Couch Level: A level was placed on the couch oriented in the

transverse and longitudinal directions and recorded the values • Couch Sag: Solid Water was placed on Head Side and then Foot

Side and displacements measured with MRI 0.3mm Head 0.39 Foot • Couch motion vs MRI coordinates: Spatial Integrity Phantom was

imaged at two known locations then fused to demonstrate proper couch motion

• Couch orthogonal to MRI coordinates: Spatial Integrity Phantom was imaged in different orientations to confirm orthogonality

Radiation/MRI versus Laser Isocenter • The radiation versus laser

isocenter was determined by using the IC profiler and confirmed with starshots

• Laser and MRI coincidence was

determined with daily QA phantom and MRI visible fiducials. The offset was determined by measuring the fiducials location versus the isocenter location.

Sagittal Laser Offset Coronal Laser Offset Axial Laser Offset -0.7 mm 0.0 mm 0.8 mm

Gantry Radiation Isocenter

• 4 Starshots were collected at various gantry angles

• determine the size of the isocenter

• Laser / RT coincidence • Due to the design of the

system films cannot be placed at isocenter manually

• The Daily QA phantom has a circular film holder for this purpose but requires laser cut film

Gantry Angle Accuracy • Radiation beams were

delivered to the Arccheck device utilizing all three heads at various gantry angles and analyzed in the Arccheck software to determine gantry angle accuracy

• Gantry angles were also confirmed utilizing starshots collected on the Daily QA phantom

Head Set Angle VR Readout AC Measured

H1 330 330 330

H1 210 210 210

H2 330 330 330

H2 90 90 90.1

H3 210 210 210

H3 0 0 0.05

H3 90 90 90.1

MLC Leakage MLC leakage films were collected on all three heads at different gantry angles to ensure leakage is within tolerance and isn’t dependent on gantry rotation.

MLC Accuracy • Employs a wire jig with 4cm

separation between wires • Measures MLC positioning

accuracy • Align the wire jig to the

sagittal laser • Treatment plan was created

for a series of MLC segments centered at 0,-12,-8,-4,4,8,12cm

• The MLC positioning accuracy is ≤0.2cm

• In house software written to process data, see us at AAPM in Washington DC.

Field Size Accuracy • Square fields were

measured with the IC Profiler with a 1 cm depth (the intrinsic buildup of the IC Profiler device)

Field Size

Field Size Axis Head Gantry Flatness Symmetry Neg_Penumb Pos_Penumb Beam Center Field Size Difference (mm)

4.2x4.2 x-measured 1 0 22.4 1.8 1.46 1.31 0.01 4.18 0.2

x-measured 3 0 22 1.8 1.44 1.29 0.02 4.25 0.5

4.2x4.2 Y-measured 1 0 20.8 -3.8 1.24 1.48 0.02 4.16 0.4

Y-measured 3 0 24.8 -8.8 1.25 1.45 0.12 4.22 0.2

10.5x10.5 X-measured 1 0 10.2 0.6 1.56 1.41 0 10.49 0.1

X-measured 3 0 9.8 0.6 1.54 1.38 0.01 10.58 0.8

10.5x10.5 Y-measured 1 0 9.5 -1.1 1.37 1.62 0.02 10.55 0.5

Y-measured 3 0 11.3 -1.4 1.38 1.58 0.12 10.54 0.4

21x21 X-measured 1 0 2.3 0.2 1.67 1.51 0.01 20.86 1.4

X-measured 3 0 2.3 0.1 0.48 0.48 0 20.96 0.4

21x21 Y-measured 1 0 2.1 -0.3 1.47 1.69 -0.02 20.89 1.1

Y-measured 3 0 2.2 -0.2 1.46 1.67 0.09 20.93 0.7

27.3x27.3 X-measured 1 0 2.7 0.2 1.74 1.57 0 27.21 0.9

X-measured 3 0 2.7 0.1 1.72 1.55 0.01 27.29 0.1

27.3x27.3 Y-measured 1 0 2.8 -0.3 1.54 1.77 0 27.22 0.8

Y-measured 3 0 2.8 -0.2 1.56 1.72 0.11 27.25 0.5

4.2x4.2 x-measured 1 90 21 2.4 1.39 1.31 -0.04 4.2 0

x-measured 2 90 22.2 4.1 1.37 1.3 -0.08 4.29 0.9

x-measured 3 90 20.8 2.4 1.37 1.29 -0.04 4.27 0.7

4.2x4.2 Y-measured 1 90 22.3 3.1 1.5 1.25 0.04 4.18 0.2

Y-measured 2 90 23.4 3.5 1.44 1.31 -0.1 4.22 0.2

Y-measured 3 90 23.2 3.7 1.45 1.29 -0.08 4.22 0.2

10.5x10.5 X-measured 1 90 8.7 0.3 1.52 1.43 -0.03 10.52 0.2

X-measured 2 90 9.3 0.6 1.5 1.42 -0.07 10.61 1.1

X-measured 3 90 8.6 0.4 1.49 1.4 -0.04 10.6 1

10.5x10.5 Y-measured 1 90 10.1 0.8 1.61 1.37 0.04 10.54 0.4

Y-measured 2 90 11.2 1.2 1.57 1.4 -0.13 10.53 0.3

Y-measured 3 90 10.9 1 1.57 1.38 -0.09 10.57 0.7

21x21 X-measured 1 90 2.2 -0.3 1.64 1.53 -0.04 20.91 0.9

X-measured 2 90 2.4 -0.2 1.62 1.52 -0.09 21 0

X-measured 3 90 2.1 -0.3 1.62 1.5 -0.04 20.98 0.2

21x21 Y-measured 1 90 2.5 0.3 1.72 1.47 0.05 20.89 1.1

Y-measured 2 90 2.8 0.1 1.69 1.47 -0.09 20.97 0.3

Y-measured 3 90 2.5 0.1 1.68 1.45 -0.07 20.94 0.6

27.3x27.3 X-measured 1 90 3 -0.4 1.69 1.61 -0.04 27.27 0.3

X-measured 2 90 3.1 -0.3 1.67 1.61 -0.09 27.35 0.5

X-measured 3 90 2.9 -0.4 1.67 1.58 -0.03 27.34 0.4

27.3x27.3 Y-measured 1 90 2.9 0.2 1.78 1.52 0.02 27.22 0.8

Y-measured 2 90 3 0.2 1.75 1.54 -0.12 27.28 0.2

Y-measured 3 90 2.7 0 1.72 1.53 -0.1 27.26 0.4

Output Calibration • A28 MRI compatible chambers

employed

• Calibration conditions: 5 cm depth in solid-water 105 cm SAD, 10.5 x 10.5 cm field.

• Beams delivered from 90 degrees in solid water phantom

• For verification, heads 1 and 3 were measured in liquid water at 0 degrees (AP beam), and these measurements matched the measurements in solid water to less than a 0.5% difference.

RPC OSLDs Report

Percent Depth Doses A28 TPS-measured

depth (mm) 4.2x4.2 10.5x10.5 27.3x27.3

3.26 1.18% 0.90% 2.94%

8.26 0.00% 0.00% 0.00%

18.26 -0.23% -0.11% -0.12%

28.26 0.03% -0.44% -0.02%

38.26 0.11% -0.46% -0.04%

48.26 -0.03% -0.66% 0.05%

68.26 0.18% 0.14% 0.12%

98.26 0.06% -0.17% 0.07%

148.26 -0.01% -0.67% 0.35%

198.26 1.39% -0.87% 0.14%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

0 50 100 150 200

Perc

ent D

epth

Dos

e

Depth (mm)

Measured vs TPS

4.2 x 4.2 TPS

10.5 x 10.5 TPS

27.3 x 27.3 TPS

4.2 x 4.2 Measured

10.5 x 10.5 Measured

27.3 x 27.3 Measured

Beam Profiles • Profiles with different depths of

solid water • Three depths (1,5, and 10cm)

with detector plane maintained at Iso (105cm SAD)

• 4.2x4.2 cm, 10.5x10.5 cm, 21.0x21.0 cm, and 27.3x27.3 cm field sizes were measured

• Same profiles were exported from the TPS and the profiler software was used to calculate the flatness and symmetry

• All profiles matched within specifications

Depth = 10 cm Field Size Axis Head Gantry Flatness %Diff Symmetry %Diff 4.2x4.2 X-measured 1 90 22.6 -0.1 3.5 6.2

X-measured 2 90 23.4 0.7 3.6 6.3

X-measured 3 90 23.2 0.5 3.5 6.2

X-calc 22.7 -2.7 4.2x4.2 Y-measured 1 90 20.2 1.2 2.5 2.5

Y-measured 2 90 20.9 1.9 3.7 3.7

Y-measured 3 90 19.5 0.5 1.8 1.8

Y-calc 19 0 10.5x10.5 X-measured 1 90 11.2 0.3 0.8 0.2

X-measured 2 90 11.9 1 1.1 0.5

X-measured 3 90 11.6 0.7 1 0.4

X-calc 10.9 0.6 10.5x10.5 Y-measured 1 90 10 1.3 0.5 0.7

Y-measured 2 90 10.3 1.6 0.8 1

Y-measured 3 90 9.4 0.7 0.5 0.7

Y-calc 8.7 -0.2 21.0x21.0 X-measured 1 90 5.5 0.4 0.2 0.2

X-measured 2 90 5.9 0.8 0.1 0.1

X-measured 3 90 5.6 0.5 0.2 0.2

X-calc 5.1 0 21.0x21.0 Y-measured 1 90 5.3 0.1 0 -0.1

Y-measured 2 90 5.5 0.3 0.2 0.1

Y-measured 3 90 5.3 0.1 0.1 0

Y-calc 5.2 0.1 27.3x27.3 X-measured 1 90 6.3 0.2 0.2 0

X-measured 2 90 6.6 0.5 0.4 0.2

X-measured 3 90 6.4 0.3 0.3 0.1

X-calc 6.1 0.2 27.3x27.3 Y-measured 1 90 6 0 0 0.1

Y-measured 2 90 6.2 0.2 0.2 0.3

Y-measured 3 90 6 0 0.2 0.3

Y-calc 6 -0.1 27.3x27.3 X-measured 1 0 6.3 0.2 0.2 0.3

X-measured 3 0 6.3 0.2 0.1 0.2

X-calc 6.1 -0.1 27.3x27.3 Y-measured 1 0 6.3 0.2 -0.1 0.2

Y-measured 3 0 6.1 0 -0.3 0

Y-calc 6.1 -0.3 27.3x27.3 X-measured 2 270 6.6 0.5 -0.5 -0.3

X-measured 3 270 6.5 0.4 -0.5 -0.3

X-calc 6.1 -0.2 27.3x27.3 Y-measured 2 270 6.2 0.2 0.3 0.2

Y-measured 3 270 6.1 0.1 0.3 0.2

Y-calc 6 0.1

Shutter Timer Error

• A28 chamber was irradiated several times for two different durations (30s and 240s)

Shutter Dose Compensation

• 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 𝐶𝐶𝐷𝐷𝐶𝐶𝐶𝐶𝐷𝐷𝐶𝐶𝐷𝐷𝐶𝐶𝐶𝐶𝐶𝐶𝐷𝐷𝐶𝐶 = 1𝑠𝑠 𝑛𝑛𝑛𝑛−200𝑠𝑠 𝑛𝑛𝑛𝑛/200200𝑠𝑠 𝑛𝑛𝑛𝑛/200

• An A28 chamber was irradiated several times for two different lengths of time (200seconds and 1second) and the compensation time is calculated using the equation shown above

• Compensation values from the configuration file was recorded and compared to the calculated value

Timer Accuracy

• A 30-second exposure was delivered for each beam. Exposure time was verified with a stopwatch with NIST-traceable calibration.

Head Set Time Measured

Time Percent Error

1 30 30.2 0.67%

2 30 30.15 0.50%

3 30 30.2 0.67%

Timer Linearity

Exposures of 5, 15, 30 and 60 seconds were measured with an ion chamber at 1.5 cm depth in solid water. The measured exposures were fit to a line and the line fit was compared to the measured value for each time.

Time (s) 5 s 15 s 30 s 60 s 5 15 30 60 5 s 15 s 30 s 60 s

H1 3.19 9.59 19.18 38.34 3.197 9.587 19.17 38.34 -0.204 0.0317 0.0386 -0.0102 -0.00204

H2 3.16 9.49 18.97 37.94 3.163 9.486 18.97 37.94 -0.0894 0.042 -0.0042 -0.001 -0.00195

H3 3.18 9.54 19.07 38.14 3.181 9.537 19.07 38.14 -0.041 0.0274 -0.008 0.0006 -0.00513

Shutter Timer Error (sec)

H Rdg Fit % Difference

Meas-Fit

Gating Latency • CIRS motion phantom • Sensor is placed a known

distance inferior to the most superior extent of motion

• Beam should trigger off when motion phantom reaches the level of this optical sensor

• Latency is discrepancy between actual beam off and optical sensor triggering.

• Measured with a four channel oscilloscope.

Gating Dosimetry

Couch Attenuation

Gantry Angle

Rela

tive

Atte

nuat

ion

TPS Statistics

Max Dose Min Dose Mean Dose Standard Deviation 1-Million Histories 10.64 8.94 9.90 0.18 16-Million Histories 10.20 9.78 9.98 0.04

• Viewray utilizes a Monte Carlo based treatment planning system

• The number of particle histories used in the calculation increases the accuracy, but…

• Using a high # of histories in adaptive planning can significantly increase the amount of time the patient is on the table.

End to End Tests • IMRT Delivery • IMRT Two Head Delivery • RPC Head and Neck Phantom • RPC Lung Phantom • TG-119 Tests

– Head and Neck – Prostate – Multi Target – C-Shape

IMRT Delivery Delivery Mode Gamma (3%, 3mm)

Full Delivery Measured to Calculated Dose 99.4 %

Interrupted Delivery: Measured to Calculated 100 %

Interrupted Delivery: Measured to Measured 99.9 %

IMRT Two-Head Mode Delivery Mode Gamma (3%, 3mm)

Full Delivery Measured to Calculated Dose 99.4 %

Two Head Mode: (Two Head Mode) Measured to (Three Head Mode) Calculated

99%

(Two Head Mode) Measured to (Three Head Mode) Measured

100%

RPC Head and Neck

Primary PTV Rx 6.6Gy

Secondary PTV Rx 5.4Gy

OAR Max 4.5Gy

Normal Tissue 7.26Gy

RPC Head and Neck Constraints

Primary PTV Rx 6.6Gy

Secondary PTV Rx 5.4Gy

OAR Max 4.5Gy

Normal Tissue 7.26Gy

RPC Head and Neck

RPC Lung

Primary PTV Rx 6.0Gy

Cord Max 5.0Gy

Heart <33% 6.0Gy

Heart <66% 4.5Gy

Heart <100% 4.0Gy

Both Lungs <37% 2.0Gy

RPC Lung Constraints Primary PTV Rx 6.0Gy

Cord Max 5.0Gy

Heart <33% 6.0Gy

Heart <66% 4.5Gy

Heart <100% 4.0Gy

Both Lungs <37% 2.0Gy

RPC Lung

TG-119 Summary Test Gamma (2.5%/2.5mm)

Head and Neck 95%

Prostate 97.4%

Multitarget 98.2%

C-Shape 96.3%

Acknowledgements • Alan Pollack, MD PhD • Radka Stoyanova, PhD • Viewray Inc: David Holloway, Maria Bellon,

Rebecca Sandbrook, James Victoria, Michael Saracen, John Ryan

• UCLA: Minsong Cao and James Lamb

• WashU: Olga Green