Igrt Perspectives

Perspectives
on IGRT

Varian Users Meeting at ASTRO 2006
November 4th, 2006. Philadelphia, PA

Our Panel

AJ Mundt, MD
Megan Gannaway, BS
Professor & Chair
Radiation Therapist

Mickey Goldman, MHA
Todd Pawlicki, PhD
Business Director
Physics Director

The Department
• Equipment, Trilogy (up to 40/day)
• Where we are going – Vision
• What we currently do with IGRT
kV/kV
CBCT
Setup
Treatment monitoring


IGRT
A Physician’s Perspective
• A long overdue technology
• Known for years that….
Patients are difficult to setup
Targets change in position between (inter-
fraction) and during (intra-fraction) treatments
Tumors and patients change over the
treatment course
• Increasingly aware that such factors effect
the quality and delivery of treatment

Wake Up Call
De Crevoisier et al. (MDAH)
Int J Radiat Oncol Biol Phys (2005)

• Impact of rectal distension
at simulation on outcome of
prostate pts
• Distension correlated with
PSA control
• Emphasized need for daily
prostate localization with
IGRT


What is IGRT?
• Difficult question to answer
• Image-guided RT (IGRT) means different
things to different people
• No consensus exists
• Some define IGRT very broadly, some
define it very narrowly
• Most don’t define it at all


RTOG Research Plan 2002-2006
IGRT Committee Report
Michalski J, Purdy JA, Gaspar L, et al.
Int J Radiat Oncol Biol Phys 2001;51:60-5

“IGRT refers broadly to treatment delivery using
modern imaging methods, such as CT, MRI, PET
and Ultrasound, in target and non-target structures
and in RT definition, design and delivery…”

“IGRT includes, but is not limited to, 3DCRT, IMRT,
stereotactic radiosurgery, stereotactic RT, and
brachytherapy….”


What is IGRT?
• Prefer a more focused definition
• Distinguish between
Image-based RT (use of imaging to
define the target and normal tissues for
treatment planning)
Image-guided RT (use of imaging to
monitor and modify treatment)


Physician Perspective
• Use of imaging to monitor and modify
treatment delivery is not new
• Various IGRT approaches have been used
for decades (EPID, ultrasound, video, etc.)
• What is new is modern IGRT approaches
take advantage of more frequent and
sophisticated imaging techniques to localize
the target with even greater accuracy


Current IGRT Technologies

Ultrasound Video-Based Planar X-Ray Volumetric
BAT Video Subtraction EPID In-Room CT
Photogrammetry CyberKnife FOCAL, MSKCC
SonArray
I-Beam AlignRT Novalis CT-on-Rails
Restitu Real-Time Video- RTRT Primaton
Guided IMRT Gantry-Mounted Varian ExaCT
Protoype Tomotherapy
Tohoku, IRIS MV Cone Beam CT
Commercial Siemens
Related Technologies
kV Cone Beam CT
Varian OBI
RPM gating/4DCT
Elekta Synergy Mobile C-arm
Optical-guided Approaches
Varian OBI
Elekta Synergy
Siemens In-Line

UCSD
• New Department
• New Cancer Center
• New Staff
Chair, MDs, Physicists,
RTTs, Administrators, etc
• New Varian Linacs
Including a Trilogy
• “Ideal setting” for
implementing new
technologies


Many Other Changes…
• Large ↑ in daily census requiring addition of
new vaults and linacs
• Busy SRS programs (brain, spine, and
body) using the frameless Trilogy system
• ↑ Volume of labor-intensive techniques:
IMRT, pediatrics, brachytherapy, etc.
• Opening of satellites
• Transition to Paperless Department

IGRT at UCSD
• Elected to do a staged implementation
• Initially focused on planar (kV) IGRT
Anatomy-based (various sites)
Fiducial (seed)-based (prostate cancer)
• Straight-forward, less time-intensive
• Now introducing volumetric (CBCT) IGRT
Predominantly prostate pts without seeds
Other selected sites
• Plan to ↑ CBCT use, introduce 4DCT/gating
and, in future, adaptive RT

IGRT at UCSD
• Majority of IGRT cases
Prostate CA with kV planar IGRT & fiducials
• Involve the referring urologists
Seed placement (2 laterally, 1 apex)
Foster a team approach
• Simulate 1 week after seed placement
• Do not place seeds and simulate until after
neoadjuvant hormonal therapy
• Develop a Process Flow

Process Flow
Planar IGRT (Prostate Cancer)
Day 1
MD and RTTs meet at console
Discuss seed positions, alignments and couch shifts

Day 2 thru Completion

Other shifts
All shifts ≤ 1 mm LR shift > 5 mm
SI or AP shift > 15 mm
Seeds drift
Make all shifts
Make no shifts
Call MD and treat
and treat


Prostate Seed Matching


Process Flow
Volumetric IGRT (Prostate Cancer)
Day 1
Identify mid-prostate images (axial, sagittal, coronal) and shifts


Other shifts
All shifts ≤ 1 mm LR shift > 5 mm
SI or AP shift > 15 mm
Difficulty interpreting
anatomy
Make all shifts
Make no shifts
and treat
and treat
Call MD

Volumetric kV CBCT Images


Gynecology
• Another potentially
important IGRT site
• All gynecology pts at
UCSD treated with IGRT
• Highly conformal IMRT
plans make IGRT
important
Notoriously difficult to
setup patients


Gynecology
• IGRT also crucial since
we are trying to spare
the pelvic bone marrow
• Difficult since it is
important to reduce the
low receiving low doses
(V10 and V20)
• All gynecology pts thus
undergo on-line kV
IGRT setup (boney
matching)


Gynecologic IG-IMRT

• To evaluate the benefit of volumetric IGRT
approaches in gynecology, a CBCT is also
obtained daily
• Unlike kV imaging, it is obtained post-RT
and analyzed off-line
• Ensure target coverage and evaluate
impact of re-planning (adaptation)


Process Flow
IGRT (Gynecology)
Day 1
Discuss anatomy and shifts


All shifts ≤ 1 mm Any Shift > 10 mm Other shifts

Make no shifts Call MD Make all shifts
and treat and treat

CBCT Varian Users Meeting at ASTRO 2006

Gynecologic IGRT
• CBCT will eventually replace planar kV
imaging for setup evaluation

• CBCT will also be used for adaptive
treatment planning


Tumors
Shrink
Bladder
Bladder

Tumor Tumor

Rectum
Rectum
Prescription
Isodose
Week 1 Week 3

• 14 cervical cancer pts undergoing RT
• MRI before RT and after 30 Gy
• Used to generate 2 IMRT plans
• Assessed impact of re-planning on
target coverage and normal tissue
sparing

Pre-RT 30 Gy

GTV

• GTV decreases on average by 46%
• Re-planning improved rectal sparing
• If >30cc GTV reduction, re-planning also
improved sparing of the small bowel

Currently use CBCT for daily setup and adaptive
RT in re-irradiation patients
56 yr old stage IIIB cervical cancer pt
Recurs 3 yrs following definitive chemoradiotherapy
Isolated recurrence in PA node at L4-L5 (½ in old field)
IMRT 59.4 Gy in 1.8 Gy fractions plus CDDP

Excellent palliative response, minimal toxicity

IGRT
A Physicist’s Perspective

• Image-guided radiotherapy is being
overvalued as a clinical tool in radiation
therapy

• Presented as a Point/Counterpoint
Med Phys (33) Oct 2006
Howard I. Amols, Ph.D.
David A. Jaffray, Ph.D.


IGRT in Radiotherapy
F = 1 − [TCP·(1−NTCP)]
0.8 0.20
RT Failure Function (F)
Quality Distribution
0.6 0.15
Expected Failures E<F>

0.4 0.10

0.2 0.05

0.0 0.00
40.0 50.0 60.0 70.0 80.0
Dose (Gy)
Figure 2


18.0%
0.5Gy SD
16.0% 1.0Gy SD
Expected radiotherapy failure

2.0Gy SD
14.0%
3.0Gy SD
12.0%
4.0 σ 4.0Gy SD
10.0%

8.0%

6.0%

4.0%
0.5 σ
2.0%

0.0%
-6.0% -4.0% -2.0% 0.0% 2.0% 4.0% 6.0% 8.0%
Figure 3 Per cent deviation from prescription dose


• Theoretical evidence – Improving quality
and precision may increase survival and
decrease complications

• 1988 Publication – Effects of dosimetric
and clinical uncertainty on complication-
free local tumor control
Boyer AL, Schultheiss T.
Radiother Oncol. 1988 Jan;11(1):65-71.

IGRT
A Physicist’s Perspective

• How can one use IGRT today?
Precise and accurate imaging
Treatment monitoring
• Quality Assurance
What and how?
• Training on image interpretation
• What is exciting about IGRT for physics?


Daily Prostate Localization


Treatment Monitoring
• Easy to import into Eclipse


OBI Clinac HW Modifications
SRS/SRT
Supervisor 6x filter RPM
kV HV cable takeup
Gating
IAS3 DU A-to-D
X1/X2 Coll Camera
Power shelf
SPRO
Laser
Guard
Auxiliary Mtn SRS
electronics Cntrl kV Collimator
Carousel Rack
Generator Detector
cntrl
In 480 V
Gantry
Out
encoder
125kV kV
Source Lat, Long, Vrt
MV
SPRO
Detector
Exact
Arm Rotation
SPRO

IGRT QA
Things to consider when implementing IGRT

• Safety and functionality
• MV/kV isocenter coincidence
• Geometrical accuracy (arm position)
• Shift calculation (MV/kV, kV/kV, CBCT)
• OBI isocenter vs gantry angle
• Image quality (kV, CBCT)
• CBCT image uniformity
• CBCT HU constancy

QA on the Trilogy
• Safety and functionality
• MV/kV isocenter coincidence
• Geometrical accuracy (arm position)
• Shift calculation (MV/kV, kV/kV, CBCT)
• OBI isocenter vs gantry angle
• Image quality (kV, CBCT)
• CBCT image uniformity
• CBCT HU constancy

kV/MV Isocenter Coincidence


kV/MV Isocenter Coincidence

Sua Yoo et al. A quality assurance program for the on-board imager.
Accepted for publication in Med Phys.
Collaborative effort: Duke, Emory, Henry Ford, Stanford, and Varian


IGRT Is Not Done Evolving

Picture courtesy of Steve Jiang, PhD; MGH


IGRT
A Therapist’s Perspective


How kV/kV impacts the schedule
• Until staff is comfortable
Schedule half hour for kV/kV matching
• Evaluating the images takes time
• After a few months
kV/kV matching only adds about 5 min to a
patients total treatment time
• Comfort with the software
Hardware takes 2-3 months for each therapist


How CBCT impacts the schedule

• 45 min time slots until staff is
comfortable
• 30 min schedule for CBCT
patients
• Some patients are CBCT
once a week, some daily
• Patients must be able to hold
still at least 30 min


A typical day on the Trilogy
kV/kV
Anatomy
40%
non-IGRT
15%
kV/kV
Seeds
20%
CBCT
CBCT
Prostate
Other
19%
6%

How do we use kV/kV
• Manually match
• Fiducials for prostate
• Bony anatomy
Pelvis
Head and neck
Thorax (though this is more difficult)
Any difficult setup


How do we use CBCT
• Prostate without fiducials
Manually match the
borders of the prostate with
the contours from Eclipse
• Other selected patients
(GYN, etc.)


What patients think about kV/kV
• Patients are curious
• Patients request kV/kV
• Patients are rarely concerned about the
length of time on the table
• Patients are reluctant to be treated
without kV/kV


What patients think about CBCT
• Patients initially unhappy about time on
treatment table
• Once patients understand CBCT
More than happy to be on the table for 30 min
• Prostate patients with a full bladder are
sometimes uncomfortable
• Non-compliant patients might not be great
candidates

Difficulties with kV/kV and CBCT

• Considerable training is needed
• Interaction between software programs
Troubleshooting errors
• Evaluating images can be difficult
• Spending less time with the patients


What do RTTs like about kV/kV

• Effective and reproducible
Internal anatomy or seeds are localized daily
• Less “chasing” external marks
• Easy to analyze with training
• Time efficient
15 min time slot possible


What do RTTs like about CBCT

• It’s interesting technology
Imaging
Anatomy
QA


QA for kV/kV and CBCT

• Daily warm-up
kV source must be warmed
Coincidence check between kV and MV
• Practice, practice, practice
CBCT a phantom early on to practice:
Hardware and software usage


In a perfect world…
• Set up an IGRT protocol before clinical
routine clinical use
Cases/Sites, imaging frequency, procedures,
thresholds, etc.
• Physicians – Please educate RTTs on
image interpretation
• Physicists – Please be near by to
troubleshoot problems


Where’s the BEEF?!


A Business Perspective
• Goal is to differentiate yourself in the marketplace
Image guided therapies are becoming the new standard
of care
• Clinical Program Development
• Educate referring physicians
Most significant impact
• Public education
Website design
• Advertising


Determine impact on the business
• New equipment or upgrade to existing
technology?
• Determine implications on existing capacity
Do we have excess capacity?
How will we accommodate increased
treatment time?
• What will be the impact on the treatment
schedule?
• Training issues


Prepare the business
• Billing setup
Update hospital charge master
Update Varis/Aria procedure detail master
Check interface to ensure information is being
transmitted and accepted accurately
Educate billing & collection staff of new
procedure codes


Reimbursement Issues
• On Board Imaging (OBI) - 77421
Stereoscopic x-ray guidance for localization
of target volume for the delivery of radiation
therapy – used for positioning of the patient
Must use kV or MV x-rays only
Has both a technical and professional
component
APC 1502 – payment rate $75.00
2007 proposed change to APC 0257 & payment
reduction to $60.14


Reimbursement Issues
• Cone beam CT (CBCT) – 76370
Computed tomography for placement of
radiation therapy fields – use for daily CT for
planning.
Technical charge only – for both hospitals and
freestanding centers
Must have case by case orders from the MD
as to why the procedure is being done and
frequency of use
APC 0282 - $94.82


Source – James Hugh III- AMAC

Website


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Ads
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on IGRT
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