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Image Guided Intensity ModulatedPhoton Radiation Therapy With

Non-Invasive Immobilization forHigh Dose Treatment of Primary

Tumors of the Spinal Column

Yoshiya (Josh) Yamada MD FRCPC, Mark H. Bilsky MD,Michael Lovelock PhD, Joan Zatcky NP, Zvi Fuks MD

Departments of Radiation Oncology, Medical Physics and Surgery,

Memorial Sloan-Kettering Cancer CenterNew York, New York

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Why Paraspinal IMRT?

Vexing clinicalproblem:

Significant morbidity

Spinal cord toleranceissues

Primary tumors

Metastatic tumors

Prior treatment

Tumor control mayrequire radiationdose greater thancord tolerance

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Radioresistant and Radiation

Dose: Conventional XRT

Metastatic PrimaryMyeloma Ewings Sarcoma

Lymphoma Neuroblastoma

Breast Carcinoma

Colon Carcinoma Superior Sulcus Tumors

NSCLCa

Thyroid Carcinoma Osteogenic Sarcoma

Renal Cell Carcinoma Chondrosarcoma

Sarcoma Chordoma

Melanoma

Sensitive

ModeratelySensitive

Moderately

Resistant

HighlyResistant

SuboptimaltreatmentHigher doses may

result in spinalcordtoxicity

Effectivetreatment

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Dose Matters: XRTFailure Analysis

141 patients with chordoma and chondrosarcoma of theskull base/cervical spine

Mixed proton beams 69 Co Gy (67 72)

26 failures

23% failed in prescribed dose region

58% failed in regions constrained by normal tissuetolerance

10% in surgical pathway 10% marginal miss

75% of failures occurred in areas with less than

prescribed dose

JP Austin et al. Int J Rad Oncol Biol Phys 1993; 25: 439 - 444

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Image-Guided Photon IMRT

Irradiating tumors tohigh doses beyondSC tolerance:

Accurate identificationof target and normalstructures

Treatment planning

Immobilization

Verification

Delivery

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IMRT: An Alternative to Proton

Beams ? Ideally suited for concave dose distributionsaround the spinal cord

Inverse treatment planning with constraints

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Cord Sparing Dose Intensity Map

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Primary Tumors (N=20)

PrescribedDose

7000 cGy 5940-7000 cGy

PTV (cc) 153 cc 86-316 cc

% PTV 90% 83-100%

Cord Max 68% 14-75%

Cord Ave (%) 31% 7-66%

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Immobilization

Non invasive image guided cradle immobilization Thoracic and pelvic pressure plates

Aquaplast mask

Alpha cradle support

MRI/CT compatible

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Set up Reproducibility

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Immobilization Performance

Immobilization determined by computing patient shift from start toend of treatment

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Image Guided Verification:EPID

Digital portal imageverification

Surgical Hardwareas Fiducial Markers

Calculatenecessary shiftwith imageoverlay

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Image Guided Verification

Fiducials

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2 D Image Guided Verification

Gold seed fiducials

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2 D Image Guided Verification

Fiducial

3 mm lateral shiftcorrection

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2 D Image Guided Verification

Fiducial Match

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3D Verification:Cone Beam CT

3-D to 3-D image matchingData for treatment plan modificationImplanted fiducial markers not necessaryLess than one minute to acquire imagesAutomated registration and set up correction calculationsRetrofit to existing LINACs

C B Fl i

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Cone Beam vs. FluroscopicImages

CT CT Verification (OBI):

Direct 3D to 3D comparison

Direct soft tissue visualization

On table simulation: 3D data

for treatment plan modification(weight loss, tumor responsesetc)

Fluroscopic 3D Verification

Indirect (2D to 3D) comparisonRelies on bony landmarks or radioopaque markers

Requires CT simulation for replan

I G id d V ifi ti

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Image Guided Verification3D to 3D Matching

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OBI Paraspinal Cone Beam Scan

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Other Advantages of Cone

Beam Less radiation for position verification

Cone beam CT 4-6 cGy

MV port film 2 cGy

Faster verification vs. portal imaging

Cone beam acquisition ~ 1 minute vs. multiple

port films Automated correction algorithms

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The Future with Cone Beam CT

Unleash the full potentialof IMRT

Reduce geometric uncertainties

Accuracy: Redefine PTV Increase Biologic Effective Dose

Hypofractionation/Single fraction radiotherapy

Real time treatment planning/modification True 4 D Conformal Therapy

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The Paradigm To DeliverAdequate Dose Safely

IMRT to spare the cord

Immobilization to reduce motion

uncertainties: Radiation is given as intended to tumor

and normal tissues

Verify isocenter position:Radiographic/Cone Beam CT

Correct for any set up errors

+/- 1 mm treatment accuracy

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Clinical Outcomes

N=20 Chondrosarcoma (5)

Other Sarcoma (9)

Chordoma (5)

Desmoid (1)

Median age=60 years (29-79)

Median follow up= 21 months (3-45) FU with MRI every 3 months

All patients followed until death

L l C t l P i

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Local Control PrimaryLesions

Local Control

0

10

2030

40

50

60

70

80

90

100

0 10 20 30 40 50

Months

Proportion Surviving

80%

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Overall Survival

Survival

0

10

20

30

40

50

60

7080

90

100

0 10 20 30 40 50

Months

Proportion Survivin

84%

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IMRT Complications

No significant toxicity

Grade 2 mucositis in 2 patients No Clinical or Radiographic Evidence of

Myelopathy/Radiculopathy/Plexopathy

80% of patients durable palliation of

symptoms

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IMRT Chondrosarcoma

1975:Chondroblastoma

12/00:ChondrosarcomaSevere biologic andradicular pain

2/7/01:OperationGross total resection

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IMRT Chondrosarcoma

6/02: Recurrence withleft hand intrinsics andbiceps 2-3/5

7/12/02: IMRTTumor: 7080 cGy/38SC: 5320 cGy

8/12/02: Completemotor recovery

4/24/03: Tumorshrinkage on MRI

9/24/04:Radiographically stable

6/02

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Conclusions

High dose photon radiotherapy sparing thespinal cord is feasible with IG IMRT

Radioresistant or inadequate doses?

Highly accurate and reliable non invasiveimmobilization is possible for multiple fractions

Preliminary clinical outcomes are favorable:

Palliation of symptoms Radiologic control

No significant toxicity