Download SBRT: Lung, Liver, Pancreas

Clinical applications of SBRT:
Lung, Liver, Pancreas
MaryLou DeMarco, MS, CMD
Susan Leuthold, CMD
Over
1000 SBRT Lung Patients
Planned at Moffitt
Lung: Sim and Immobilization
Gantry Collision Check
Contours: PTV/GITV
Contours: RINGS
RING100
RING100
RING
RING
Boarding Pass: Constraints
Case Study: Lung SBRT, Previous Tx
Previous Tx Right On New PTV
Make Contours Out Of Previous Tx
Isodose Lines
OARs
Lungs: Minus GITV
Challenge: Chestwall Dose
PTV_edit
PTV_edit
Chestwall_R: 3cm up and down
RING_100
RING
2 Arc Beams
Prescription: 1000 x 5 = 5000cGy
Optimizer: First Ring
First Isodose Rings that we get
The Rest Of The Rings: 6
Rings Into Optimizer With EUD @0.6
Rings to Max DVH & 0.09
Isodose Lines Pull In
Make Ring of 50% Line
The 50% line in Optimizer: EUD
The 50% Line In Optimizer: Max DVH
Gradient Index: RTOG
549.1 / 201.1 = 2.7
From RTOG: a 201.1cc PTV needs a Dose Gradient
< 3.3, so the Dose Gradient is good
OARs
Previous Tx Areas Into Optimizer
Isodose Lines
Graded Plan Into Mosaiq
SBRT of the
Pancreas and Liver
Susan Leuthold, CMD
Dosimetry at MCC…
Specializing
Primary and secondary services
GI and Sarcoma
Esop, panc, gastric, adrenal, liver, gb, rectal,
anal
• Sim and treat (palliative)
• 3D, IMRT, SRT, SBRT, HDR, LDR, Intra-op
• My Team
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Advantages of SBRT
• Shorter treatment course
– Less scheduling conflicts
– Less driving, lodging
– More likely to complete tx
• As effective (increase dose and local control)
• Ease of planning
• Overview of pancreas cancer
• Definition of borderline resectable
• Treatment technique
– SBRT (3D gated) also use IMRT/VMAT
• Then on to Liver (3D gated Vs. IMRT)
The Pancreas
What does the pancreas do?
• Hormone production (endocrine)
– Insulin – decrease glucose
– Glucagon – increase glucose
– Somatostatin – regulate insulin/glucagon
production
• Digestion (exocrine)
– Break down protein, carbohydrates, and fat
– Neutralize acid from stomach
Pancreas Cancer
• 9th most common cancer but 4th most
common cause of cancer death in U.S.
• ~50,000 new diagnoses per year
• Most present at advanced stage
• 15 – 20% resectable at diagnosis
• R0 resection offers chance for cure
Pancreas Cancer
• Most present at advanced stage
• Clinical presentation
– Jaundice
– Weight loss
– Diabetes
– Abdominal pain
– Pruritus (itchy sensation)
– Steatorrhea (excess fat in stool)
Pancreas Cancer
• Prognosis is grim
– Long-term survival for all patients 3 – 4%, 5 yr
– If have surgery 5 yr survival to 20%
– “systemic disease”
• Median survival
– After resection: 12 – 26 months
– Locally advanced: 9 – 13 months
– Metastatic: 3 – 6 months
Definitions
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Resectable
Locally advanced – non-resectable
Borderline resectable
Resection classification
Borderline Resectable
Definition
1. ≤180° circumferential tumor abutment of portal
vein (PV), superior mesenteric vein (SMV), or
superior mesenteric artery (SMA)
2. Short segment (1.5 cm) encasement of PV or SMV
amenable to partial resection and reconstruction
3. Gastroduodenal artery encasement to origin of
hepatic artery
Resectable
SMV
Locally advanced/unresectable
Tumor
SMA
Borderline-resectable
Tumor
SMV
Margin definitions
• Negative margins
– R0
• Microscopically positive margins
– R1
• Grossly positive margins
– R2
Goal of treatment
• Complete surgical removal of the tumor
• With no cancer at the edges of the specimen
Our approach
 Chemo (GTX) over 9 weeks
Gemcitabine (IV infusion)
-Taxotere (IV infusion)
-Xeloda (oral)
• Then SBRT for 5 days
• Re-eval for poss resection
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Re-evaluation 3-4 weeks after
• Restaging PET/CT
• Tumor board presentation to see if lesion has
shrunk away from blood vessel enough for
surgeon to attempt resection
SBRT planning
• Tumor localization
– Find tumor location accurately for each fraction.
• Patient simulation
– Modified simulation for SBRT
• SBRT planning (3d gated or IMRT)
– In this case, we create a set of beam angles and portals
that deliver the treatment & the boost simultaneously –
Dose painting
– Gated if a lot of motion
Prior to Simulation
• Patient undergoes implantation of
fiducial markers
– Done via Endoscopic ultrasound (EUS)
– Place 3-4 gold fiducials into the tumor itself
– Fiducial markers will be useful for target
delineation and for daily image guidance
Fiducial markers
Motion
• Fluoro-sim before CT sim
• Short term solution
• Look at motion in orthog planes
Motion analysis: how much does the
pancreas move
• Superior to inferior range
– ~ 1 cm
• Medial to lateral
– ~ 1 cm
• Ant – Post
– ~ 1 cm
At simulation
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Full length custom cradle immobilization
Arms up overhead
Simulate on empty stomach
Oral gastrograffin at least 30 mins prior to sim
IV contrast with time delay to capture venous
phase.
Evaluate the motion
4D CT
Evaluate the phases of maximum exhale
Usually 40-60%
If 50% is maximum exhale, this will be primary
dataset
• Fuse the 40 and 60 and the free breathing for
target delineation.
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Gating box: measures respiratory excursion
Motion during treatment
SBRT planning
Beam angle selection
Blocking
Jaw setting
MLC settings
Off kidneys
Prescription
• Multi-level prescription
• Prescribe to lowest dose level
• Prescribe to 85% isodose
– Will adjust later
• Typically 5 fractions
• Start with 15 MV
– Adjust lower if needed
• Equally weight all beams
– Will adjust later
• Compute
Preliminary dose
Dose volume histogram
Field-in-field
MLC setting
Intermediate dose
PTV 30
DVH post calculation
Segment weight optimizer
• NOT IMRT!
• SWO will not “rescue” OAR objectives
• Min MU set to 10.
Segment weight optimizer
Final plan
Final DVH
Examples of Dose Painted Plans
More examples
Interesting examples
Multiple prescriptions
• The only chance a patient has for cure is
if surgery is possible
• A sub-class within the unresectable
classification that is deemed borderlineresectable
• By sufficiently shrinking the tumor with
neo-adjuvant therapy these cases can
become resectable
• Using this technique…
– Of the borderline-resectable patients more
than half have been down-staged to
resectable.
• These patients are given the highest
chance of long term survival.
Example outside the pancreas
Multiple PTV objectives simultaneously
achieved
LIVER SBRT (GATED) 3D
Beam Angles
Pre-conformed collimators
MLC Blocking
Conformed collimators
Sup/inf opened ~1cm
Sup/inf opened ~1cm
MLC opened accordingly
Prescription
Equal weighting
Dose objectives
Dose Volume
Histogram
Final Beam Weights
IMRT just for fun
Temp and Ring
Optimizer
3D versus IMRT SBRT
Questions?