Motion Simulator for Proton Therapy Paul Morel November, 17 2014 - - PowerPoint PPT Presentation

Motion Simulator for Proton Therapy

Paul Morel November, 17 2014 ´ Ecole Doctorale MSTIC

Paul Morel MSPT 1 / 45

Doctoral thesis:

Directed by St´ ephane Vialette (LIGM, Universit´ e Paris-Est Marne La Vall´ ee, France) Co-directed by Xiaodong Wu (University of Iowa, USA) and Co-supervised by Guillaume Blin (LaBRI, Universit´ e de Bordeaux, France)

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Main problematic:

How can we improve the robustness of proton therapy treatments when the patient moves during the delivery (intra-fraction motions)?

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References

Outline:

Proton Therapy MSPT: Motion Simulator for Proton Therapy Motion Compensation Conclusion

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Proton-Therapy

Cancer treatment relying on ionizing radiation aiming at killing cancerous cells using proton beams.

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Why protons?

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Why protons?

Comparison of irradiation: photons (upper panels) versus protons (lower panels) [Kirsch and Tarbell, 2004]

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Why not only protons?

Proton accelerator Beamline Gantry Nozzle Patient Courtesy of V. Collignon, IBA

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Why not only protons?

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Proton therapy - an analogy

Water pressure = Proton energy (⇒ depth of Bragg Peak) Water quantity = Dose (! Quantity of protons) Water drops are deposited on the way = Dose is cumulative along the way

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Proton therapy - an analogy

Water pressure = Proton energy (⇒ depth of Bragg Peak) Water quantity = Dose (! Quantity of protons) Water drops are deposited on the way = Dose is cumulative along the way

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Proton therapy - an analogy

Water pressure = Proton energy (⇒ depth of Bragg Peak) Water quantity = Dose (! Quantity of protons) Water drops are deposited on the way = Dose is cumulative along the way

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Proton therapy - an analogy

Water pressure = Proton energy (⇒ depth of Bragg Peak) Water quantity = Dose (! Quantity of protons) Water drops are deposited on the way = Dose is cumulative along the way

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Proton therapy - an analogy

Water pressure = Proton energy (⇒ depth of Bragg Peak) Water quantity = Dose (! Quantity of protons) Water drops are deposited on the way = Dose is cumulative along the way

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Main principle: energy layers

Energy layers

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Pencil beam scanning

Discrete scanning: The beam is turned off between the spot positions.

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Treatment planning

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Treatment planning

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Treatment planning

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Treatment Planning

weight ! dose ! quantity of protons ! duration

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Sensitivity to motion

Inter-fraction motions: loss/gain of weight, tumor swelling/shrinkage, bladder, intestinal gas... Intra-fraction motions: breathing, heart beat ...

Results of irradiations without (left) and with (right) motion on a radiographic film.[Bert et al., 2012]

⇒ Treatment quality reduced

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Motion mitigation techniques

Motion reduction: abdominal press, breath-hold, breath coaching, anesthesia. Motion mitigation: beam-gating, repainting, beam tracking.

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Why protons? Why not only protons? Proton therapy - an analogy Delivery techniques Treatment planning Motion Problematic

Problematic:

How can we improve the robustness of proton therapy treatments in case of intra-fraction motions?

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

MSPT: Motion Simulator for Proton Therapy

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

MSPT overview

Main objective Render the impact of intra-fraction motions for given treatment plans. ⇒ Assess the treatment quality and develop new strategies.

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

About MSPT development

A 3-year project Good understanding of proton therapy:

Physics Clinical treatment

Good understanding of RT DICOM standard

• Ref. data and settings from: Raysation 1 (⇒ reverse engineering), PSTAR 2

Programmatically: Python with C sub-routines, ∼ 12, 500 lines of code Open-Source available at: http://code.google.com/p/mspt/ Well documented

1RaySearch Laboratories 2http://physics.nist.gov/PhysRefData/Star/Text/PSTAR.html

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

Patient data

Patient is modeled by a set of matrices: Patient tissues: CT # ⇒ 3D mass density matrix. Patient ROIs (tumor, organs ..): RT structure set information ⇒ 3D binary matrices.

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

Physical data

Depth dose curve generated from dose distributions in a water tank simulated in RayStation (RaySearch lab.) for energies ranging from 30MeV to 230MeV (step 5MeV). Conversion depth in water ↔ depth in patient: radiological depth. Missing energies (e.g., 101.5MeV..): Approximation of the depth-dose curve from computed data.

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

Dose calculation

Analytical model [Hong et al., 1996]: Main functions d(x, y, z) = C(z)O(x, y, z)

C(z) = DDw(rpl(z), E0) ∗ ✓ssd0 + rpl(z) z ◆2

O(x, y, z) = 1 2π(σtot(z))2 ∗ exp ✓ − x2 + y 2 2(σtot(z))2 ◆

Auxiliary functions σtot(z) = q σ2

size + σpt(z)2

σpt(z) = y0(rpl(z))

y0(t) = y0(R) ∗  0.69 ∗ ⇣ t R ⌘2 + 0.33 ⇣ t R ⌘ y0(R) = 0.12085 × 104 ∗ R2 + 0.02275 ∗ R

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

Model evaluation

Comparison to RayStation results: Single beamlets in water tank, energies from 30MeV to 230MeV: Dose profile at 130 MeV and Bragg Peak vs Energy:

50 100 150 100 200 300 400 Depth (mm) Dose.Area (Gy.cm2) 50 100 150 200 250 100 200 300 Energy (MeV) Bragg Peak Depth (mm) RayStation MSPT Paul Morel MSPT 24 / 45

Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

Model evaluation

Comparison to RayStation results: Single beamlets in water tank, energies from 30MeV to 230MeV: Lateral profile at Bragg Peak (130 MeV) and σ vs Energy:

−40 −20 20 40 0.2 0.4 0.6 0.8 1 Depth (mm) Dose.Area (Gy.cm2) 50 100 150 200 250 5 6 7 8 9 Energy (MeV) Sigma (mm) RayStation MSPT Paul Morel MSPT 25 / 45

Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

Model evaluation

Treatment simulation:

RayStation dose distribution MSPT dose distribution

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

Model evaluation

Treatment simulation:

50 100 150 200 20 40 60 80 100 Dose (cGy) Relative Volume (%) RayStation MSPT Bone Esophagus Right Lung Tumor

DVH comparison between RayStation and MSPT.

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

Model evaluation

Treatment simulation: limits of the comparison to RayStation

RayStation MSPT Difference

Cold spots Hot spots

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

Model evaluation

Treatment simulation: limits of the comparison to RayStation

500 1,000 1,500 2,000 20 40 60 80 100

Hot spots Cold spots

Dose (cGy) Relative Volume (%) RayStation MSPT Right Lung Tumor

DVH comparison between RayStation and MSPT.

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

Motion

We consider a patient moving during the treatment: f (x, y, z, t) → (x0, y 0, z0)

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

Motion

Render motion impact: tunit

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Overview About MSPT Patient data Physical data Dose calculation Model evaluation Motion

Motion

We consider a patient moving during the treatment (right):

50 100 150 200 250 20 40 60 80 100 Dose (cGy) Relative Volume (%) Static Dynamic Bone Esophagus Tumor Right Lung Paul Morel MSPT 32 / 45

Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Compensation principle Compensation algorithm Application to a large motion

Motion Compensation

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Compensation principle Compensation algorithm Application to a large motion

Compensation principle

Static Dynamic: No Compensation Dynamic: Compensation

⇒ Approach based on the pencil beams’ weight adaptation. Limited to 2D motions orthogonal to the beam’s direction.

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Compensation principle Compensation algorithm Application to a large motion

Compensation algorithm: Overview

General compensation algorithm

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Compensation principle Compensation algorithm Application to a large motion

Compensation algorithm: ”Compensation possible?”

Algorithm determining if the compensation is possible.

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Compensation principle Compensation algorithm Application to a large motion

Application to a large motion

2 4 6 8 10 −1 1 Time (s) x(t) (cm)

Illustration of a large irregular motion

Motion orthogonal to beam direction:

• Amp. cm

σAmp. cm τ s στ s X 1.5 0.3 4 0.4 Y 1.5 0.3 4 0.4

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Compensation principle Compensation algorithm Application to a large motion

Application to a large motion

Resulting dose distributions (transverse planes):

Static No Compensation Compensation

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Compensation principle Compensation algorithm Application to a large motion

Application to a large motion

Resulting dose distributions (coronal planes):

Static No Compensation Compensation

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References Compensation principle Compensation algorithm Application to a large motion

Application to a large motion

500 1,000 1,500 2,000 20 40 60 80 100

95 95% of prescribed dose

Dose (cGy) Relative Volume (%) Static No Comp. Comp. Spinal Cord Right Lung Tumor

Comparison of DVHs for a delivery on a static and dynamic patient with and without compensation.

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References

Conclusion

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References

Conclusion

Open-source PT simulator available for future research. Render the impact of the motion on the dose distribution. Tool to evaluate the robustness to motion. A new approach adapting the beam’s weight to improve the robustness. Possible future research: Implement a deformable motion model in MSPT. Extend compensation strategy to 3D motions.

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References

Acknowledgments

My directors and supervisor:

St´ ephane Vialette Xiaodong Wu Guillaume Blin

Members of my committee:

Dongxu Wang Cyril Nicaud Pascal Desbarats Serge Miguet

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References

Acknowledgments

Members of the Dpt. of Radiation Oncology (University of Iowa, USA):

Dongxu Wang Ryan Flynn Edgar Gelover Reyes Daniel Hyer Yusung Kim

Christina Zacharatou from Institut Bergoni´ e, Bordeaux (France) Work fully supported by ANR project BIRDS JCJC SIMI 2-2010

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Proton therapy MSPT: Motion Simulator for Proton Therapy Motion compensation Conclusion Acknowledgments References

Thank you!

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