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Surface Guided Radiotherapy for Accuracy, Volume Reduction, Real time Tracking and Dose Verification
1. Surface Guided Radiotherapy for
Accuracy, Volume Reduction,
Real Time Tracking and Dose
Verification
Simon Powell MD PhD
2. Surface Guided Radiotherapy
Monitor treatment position within RT delivery time
Competing technologies? MRI! 3D-Ultrasound?
Accuracy of surface topology to predict
internal tumor and organ position?
Set-up time and accuracy
Compared to kV imaging
Deep inspiratory Breath Hold
Respiratory motion tracking and gating
3. Workflow Process at MSKCC
3
Each site has at least one AlignRT
Same procedure: set displacement limits
CT SIM with immobilization
iPlan
AlignRT based treatment
5. Real-Time Variance “Deltas” (RTD)
5
Real time register Verification
surface to Reference surface to
calculate:
All 3 translational displacements
and their MAG
All 3 rotational displacements
RTD < threshold Beam ON
6. Surface Guided Radiotherapy
Brain SRS
Maskless or Open-mask, Head & Neck Cancer
Breast Cancer
DIBH comprehensive treatment
DIBH whole breast
Partial breast irradiation
Lung/Upper Abdomen
Respiratory Gating (and tracking?)
7. Frameless SRS
Similar clinical result but much better patient
comfort
UCSD data on clinical results:
No frame better patient comfort
More convenient for both patients and treatment
centers
CT SIM and treatment do not need to be at the
same day
Multiple lesions can be treated in 2-3 days
Outpatient based regional sites can treat SRS
8. 0
50
100
150
200
250
2010 2011 2012 2013 2014 2015
Numberofcases
Year
Framelesspatients
Framelesslesions
Frame patients
Frame lesions
SRS at MSKCC from 2010 to 2015
First AlignRT patient (Aktina)
First CDR patient
6 DOF, HD 120 MLC
85/15/2015
(Jan.- April)
9. SRS treatments at MSK
• AlignRT-guided treatment IGRT procedure
and VMAT SRS planning allows growth in
program
Year Method Patient Tumor
2014 Framed SRS 125 244
2015 f-SRS 240 360
2016 f-SRS 347 650
2017 f-SRS ~450 ~900
11. Brain Frameless SRS
MSKCC clinical practice
• AlignRT-guided patient setup is fast (<60s) and
accurate (<2mm), best for fast patient alignment
before CBCT.
• AlignRT-guided motion monitoring of patient motion
ensures frameless SRS accuracy (<1mm).
• The patient treatment throughput doubled since we
shifted from frame-based SRS to frameless SRS.
• Physicians, physicists and therapists are all happy with
AlignRT performance in frameless SRS treatments, and
have extended the procedure to treat brain SBRT
patients with reduced margin to 2mm (from 3mm)
13. Example: Head Immobilization
• Motion range is
generally within
1.0mm
• Entire treatment
is monitored
using AlignRT
• Auto-Beam hold
is available, but
we don’t use it.
14. Head & Neck Cancer
Open mask or maskless H&N cancer treatments
rapid position verification
monitoring of movement during treatment
Level of precision is sub-mm
longitudinal axis has some drift seen, but also
sub-mm
Real-time verification is most useful in periods of
waiting for CBCT: reduce the need for re-imaging
15. AlignRT based DIBH
Previously, we usedVarian RPM-based DIBH
Started implementing AlignRT based DIBH in Jan
2015 (left-sided)
Treated > 40 patients
Region of Interest is critical
New applications:
Right-sided breast DIBH
Electron boost
17. Verify if patient breath hold is reproducible, and if
patient can hold breath for 20 seconds.
Whether DIBH is beneficial for this patient?
Free Breathing Breath Hold
Deep Inspiratory Breath Hold
21. Tangents+SCV, or IMRT, or VMAT?
Wide tangents + SCV: cannot avoid Rt breast
Then IMRT: 18 fields (9-static, split field)
FinallyVMAT: 4 arcs
IMRT VMAT
Mean heart dose (cGy) 819 645
Lungs V20 Gy (%) 18 16
Mean Rt breast dose (cGy) 452 825
Total MU 2103 1090
Number of fields 9 × 2 = 18 4
22. Breast, Chest Wall and Nodes
To minimize breast tissue deformation between
simulation and treatment
(A) Arm variation can occur (B) Arm Aligned patient setup
23. Orthogonal Pair for Isocenter Verification
23
AlignRT surface matching is equivalent or better than bone match
Using CBCT as the final arbiter
27. Electron Boost for DIBH RT
Used to be treated in free breathing
Electron cone in the way
RPM cannot track either
This is OK for most scenarios as electron is
superficial
We have successfully implemented electron
workflow in the clinic
30. Breast Cancer SGRT
• The arm and chin alignments are necessary to
minimize tissue deformation, prior to the breast
alignment.
• AlignRT patient setup procedure has ensured that we
treat patients the same way as planned
• No other technique offers such capacity to control and
minimize tissue deformation
• The AlignRT technique has been tested for treating PBI
patients.
• The AlignRT technique has been applied to treat DIBH
patients.
33. Lung Motion in IGRT
• Extension of AlignRT applications from rigid to
deformable/mobile anatomic sites
• Organ motion/deformation is a clinical challenge and
affects the treatment precision and outcome.
• Optical imaging of entire torso provides a physical
closed system
• The development of this technique is on hold, after the
proof-of-principle study.
37. Conclusions
We have applied SGRT by AlignRT to:
SRS, Head & Neck
Left breast DIBH, right breast (DIBH), electrons
Exploring more clinical applications
Protons?
Gating andTumor tracking
Clinical trial opportunities
38. Commissioning
38
Safety interlock
System stability/drift check
RTD accuracy and constancy tests
Gating function check
Gated beam output is within 2% of baseline
End-to-End test
Check I/O, iso location, skin rendering, and patient
name and ID