supervisor: dr. vincenzo monacodottorato.ph.unito.it/studenti/pretesi/xxviii/varasteh.pdf ·...

Supervisor: Dr. Vincenzo MONACO

Adviser: Dr. Anna VIGNATI

Supervisor: Dr. Vincenzo MONACO

Adviser: Dr. Anna VIGNATI

Second year PhD seminar (XXVIII cycle)

Department of Physics Torino, 20 February 2015

Second year PhD seminar (XXVIII cycle)

Department of Physics Torino, 20 February 2015

Candidate: Mohammad VARASTEH ANVARCandidate: Mohammad VARASTEH ANVAR

2 Second year PhD seminar (XXVIII cycle)Torino, 20 Feb 2015

OutlineOutline

Introduction and Motivations• Charged particle therapy• CNAO• Quality Assurance procedure in a hadrontherapy center

Conferences and Publications

Part I: Beam quality control Materials and Methods Results Prespectives and Conclusion

Part II: Online control of dose deposition Materials and Methods Results Perspectives and Conclusion


Radiation therapy to treat cancerRadiation therapy to treat cancer

Ionizing radiations have enough energy to damage molecules such as DNA

Cancer cells are more sensitive to radiation damage (not always true )

Less able than healthy cells to repair the damage

Radiation beam can be focused on the area aimed to be treated

DNA damage

E > 30 eV

X-rays Gamma

Charged particle beam


Charged particle therapy (Hadrontherapy)Charged particle therapy (Hadrontherapy)

Hadron (p, C+6) physical advantages:

• Low dose at the entrance

• High LET

• A high peak dose deep into the body

• A sharp dose falloff behind the peak

• High resolution on dose delivery

Bragg peak can be spread out inside the tumor volume to cover whole the target.

Fotoni Protoniprotonphoton


Italian National Center for Oncological Hadrontherapy (CNAO)Italian National Center for Oncological Hadrontherapy (CNAO)

Accelerator : 2 electron cyclotron resonance sources GSI linac Injection of particles in main ring as medium

energy beam transfer

• Energy range between 60-250 MeV (~ 3-32 cm in water) for proton and 120-400 MeV/u (~ 3-27 cm in water) for carbon ion

• Maximum beam intensity is 1010 protons per spill or 4x108 C+6 per spill

• 3 treatment rooms

• Clinical activities started in: October 2011 with P & November 2012 with C

Equipped with both proton and carbon ion beam


CNAO dose delivery system (DDS) based on active scanningCNAO dose delivery system (DDS) based on active scanning

Synchrotron Linac

Proton source

Nozzle and monitor system z

y SLICES of Tumor volume

Carbon source

x

Scanning magnets

(X, Y) Active Scanning

(Z) Particle Energy(Variation through the accelerator)

Data flow starts from Treatment planning system (TPS):

Definition of target volume and Organ at Risk (OAR) by the CT CT will be sent to TPS to make the treatment plan Dose fractionation based on the protocols Each fraction composed by 2 or 3 fields Target is divided into several slices for each field Each slice is irradiated with spots Each spot is defined by (Np, ∆X, ∆Y, En)

Data flow starts from Treatment planning system (TPS):

Definition of target volume and Organ at Risk (OAR) by the CT CT will be sent to TPS to make the treatment plan Dose fractionation based on the protocols Each fraction composed by 2 or 3 fields Target is divided into several slices for each field Each slice is irradiated with spots Each spot is defined by (Np, ∆X, ∆Y, En)


Aim of this workAim of this work

Daily QA checks the:

Dose Intensity Beam Offset SOBP dose Bragg Peak (field size) Beam Position Reproducibility Dose Delivery Patient-specific QA

Using:

GAFCHROMIC® EBT film DDS in Nozzle Several types of detectors(PinPoint, Farmer Ionization Chamber)

The goal is to assess the role that a 2D ionization chamber array, (called MatriXX), can play in the routine ion beam therapy Quality Assurance (QA) as a real-time tool.

QA procedure has to check all the beam parameters to ensure the accurate delivery of treatment doses to patients.

8

Two-dimensional ionization chamber array (MatriXX)Two-dimensional ionization chamber array (MatriXX)

MatriXX (IBA, Be), is a pixel-segmented ionization chamber.The original prototype has been designed and built by Torino University and INFN [Med. Phys. (31) 2 - 414].

Device characterization: 32×32 cylindrical ionization chambers 4.5 mm diameter 7.62 mm center-to-center separation 24×24 cm2 active area Can be read out in 0.5 ms Sensitive volume of each ionization chamber is about 0.08 cm3

Count unit is 200 fC (total count is proportional to the deposited dose)

Second year PhD seminar (XXVIII cycle)Torino, 20 Feb 2015


MatriXX as a tool to check the Proton beam QAMatriXX as a tool to check the Proton beam QA

Proton beam depth dose curve in water obtained using Markus chamber and using MatriXX without and with buildup material thickness correction, achieved by MD Anderson.

The device is designed primarily for conventional radiotherapy field verification.

At University of Texas MD Anderson Cancer Center, MatriXX was investigated for proton beam QA check [Med. Phys. (35) 9 - 3889].


MatriXX for verifying the Carbon Ion beam dose delivery at CNAOMatriXX for verifying the Carbon Ion beam dose delivery at CNAO

Proton beam of 131.44 MeV and carbon ion beam of 221.45 MeV

We focused on:• Beam position• Beam width• Field dose uniformity and flatness

MatriXX in conjunction with OmniPro-I’mRT® software (IBA, Be)

Chosen sampling time: 500 ms

Data analysis implemented with NI LabVIEW

Typical beam width Carbon ion: 6 mm Proton: 10 mm


Beam position measurementBeam position measurement

2) 1010 protons per spot

1) 30×106 C+6 per spot Beam Spot

Beam Step

fitting

Following a pattern on a 7×7 grid, step of 26 mm:

Deviations from straight line

Maximum deviation: 400 µmResolution (rms): 150 µm

Maximum deviation: 20 µmResolution (rms): 7 µm


Tilted MatriXX is exposed to carbon ion and proton beam following a pattern on a 7×7 grid, step of 26 mm and 30 mm.

2) 3×108 protons per spotMaximum deviation: 30 µm(rms = 10)

1) 30×106 C+6 per spotMaximum deviation: 750 µm(rms = 250)


Simulation to check the MatriXX position errorSimulation to check the MatriXX position error

Being the width of carbon ion beam rather small (FWHM~6 mm) with respect to the MatriXX chamber pitch, one has to correct according to the beam position.

The deviations are furtherly applied as corrections to the actual MatriXX measurements.

D

7.62 mm

X

With the simulation we determined the position corrections, accounting for chamber geometry, as a function of the beam displacement, D, with respect to two adjacent chambers


For protons:

For Carbon:

As expected the corrections for Carbon are more relevant that those for protons.

Corrections as a function of the distance between chambersCorrections as a function of the distance between chambers

Proton spots position (step of 3 mm)

Carbon ion spots position (step of 3 mm)

A correction is needed for C+6A correction is needed for C+6

15

221.45 MeV carbon ion beam as a 6×6 cm2 square field (horizontal step of 2mm):

Positions before correction

Positions after correction


Applying the correctionsApplying the corrections

(mm)

I should apply the correction for tilted MatriXX as well…


Beam width determination (MatriXX and Film)Beam width determination (MatriXX and Film)

Considering 5×5 pixels around center of carbon ion beam, FWHM was calculated:

2) From GAFCHROMIC film(calculated by Gaussian fit)FWHMx: 6.4 mm, FWHMy: 5.3 mm

2) From GAFCHROMIC film(calculated by Gaussian fit)FWHMx: 6.4 mm, FWHMy: 5.3 mm

1) From MatriXXFWHMx: 7.3 mm, FWHMy = 5.1 mm(with 2.5 mm deviation in y direction)

1) From MatriXXFWHMx: 7.3 mm, FWHMy = 5.1 mm(with 2.5 mm deviation in y direction)

MatriXX and GAFCHROMIC® EBT film are exposed to carbon ion beam following a pattern on a 3×3 grid, step of 10 cm.

Count of each single pixel

For 1010 protons per spot, MatriXX gives:FWHMx: 13.6 mm, FWHMy: 13.3 mm For 1010 protons per spot, MatriXX gives:FWHMx: 13.6 mm, FWHMy: 13.3 mm


Flatness (MatriXX and Film)Flatness (MatriXX and Film)

Gafchromic film positioned on MatriXX entrance was irradiated with 5×106 C+6 per spot as a uniform 6×6 cm2 square field.

Relative st.dev. of pixels which count more than 90% of maximum is found to be 1.4%.

Flatness ~ 2%Flatness ~ 2%

Flatness = 2.3%Flatness = 2.3%

Flatness = 2.5%Flatness = 2.5%

Flatness ~ 2%Flatness ~ 2%

2D dose verification…

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To check the dose uniformity over a square field of 6×6 cm2 we derived the relative standard deviation from being constant of 2x2, 4x4 and 6x6 pixels from MatriXX measurement.


Field dose uniformity (MatriXX and Film)Field dose uniformity (MatriXX and Film)

Normalized St. Dev. (%) (C ion beam)

Normalized St. Dev. (%) (Proton beam)

Uniformity acquired from MatriXX is better than 1.5%.

The results are in agreement with those obtained from film.

19

Level of accuracy reached shows that the MatriXX is quick and accurate for use in QA procedures with hadron beams. It provides rapid 2D dose distribution information and precise beam position resolution in real time.

Writing a paper is undergoing…

Level of accuracy reached shows that the MatriXX is quick and accurate for use in QA procedures with hadron beams. It provides rapid 2D dose distribution information and precise beam position resolution in real time.

Writing a paper is undergoing…

Conclusion and perspectivesConclusion and perspectives



A GPU-based Planning and Delivery System to treat moving targets with therapeutic scanned ion beams

+ +

CNAO DDS Target tracking system(Respiratory Phase detection)

Fast Dose Computation based on GPU

On-line Dose Planning and Delivery System in charged particle therapy

RIDOS; Real-Time Ion Dose Planning and Delivery System (INFN Project)RIDOS; Real-Time Ion Dose Planning and Delivery System (INFN Project)


GoalGoal

PLANNED DOSE DELIVERED DOSE

The first goal is to develop a fast procedure for the on-line comparison of the planned dose with the actual delivered dose taking into account the movements of the target using 4DCT.

Forward Planning


RIDOS will use the Inter-Spill time!RIDOS will use the Inter-Spill time!

3÷5 sec

3÷5 sec

3÷5 sec

3÷5 sec

Using beam and target monitoring, in inter-spill time

RIDOS will perform a fast forward planning.

Inter-spill time at CNAO is 4 sec.

Time possibility?!


Computation time comparison and Dose comparisonComputation time comparison and Dose comparison

Gain factor

Increase in the number of points DEK time continuously increase

(DEK)Dose Engine Kernel

50000 secDose computation

GPUDEK (on CPU) Dose Difference


Four-dimensional computed tomography (4DCT)Four-dimensional computed tomography (4DCT)

• How the tumor moves• How movement of nearby organs affects the position of the tumor• How to correlate the position of external markers seen by the tracking system to the tumor position

4DCT demonstrates:4DCT demonstrates:


Partial dose distribution calculation of six different respiratory phases.

The targetrepresented in these plots is fromreference CT (CT00).

Using DEK TPS to assess the moving target applying the 4DCT (Thanks to Dr. Attili)Using DEK TPS to assess the moving target applying the 4DCT (Thanks to Dr. Attili)

Patient


• Monitoring the tumor movement and external markers• Detecting the current respiratory phase

4DCT

• Dose Distribution on the current CT• Updating the partial dose (on-line)

Tracking systemTracking system

WS with GPU


Dose calculation on the reference CTDose calculation on the reference CT

Correlating the calculated dose distribution of the given CT to the reference phase.

Correlating the calculated dose distribution of the given CT to the reference phase.

After each spill a comparison between planned and actual dose distribution is performed.

Phase 1Phase 2

Phase 3

Phase 10

. . . .

TPS is performed on reference CT

Reference CT

HOW?


Image Registration FrameworkImage Registration Framework

Task of finding a spatial transform mapping an image into another.

At the moment I am using a method for registration

called: BSpline


DVF is defined on fixed image and maps fixed image to moving image

BSpline registration methodBSpline registration method

Deformation Vector Fields (DVF) ?!

DVFs are computed using BSpline interpolation from the known deformation

values of the points in a grid nodes.


Off-line studies using DEK TPS to apply DVFs of RayStation softwareOff-line studies using DEK TPS to apply DVFs of RayStation software

Each phase dose distribution is remapped on the reference CT applying the DVF (RayStation).

(the movement is more along the Z direction).

del --> Deliveredplan --> Planned

After mapping partial doses distribution to the reference CT we calculate the total dose delivered and compare it with planned dose.


ITKRegistration resultITKRegistration result

From RayStation with almost 200×200×200 grid nodes

Result of our first version algorithm based on ITK with almost 50×50×50 grid nodes

SegmentationSegmentation


Why bad result? No. of Grid NodesGrid Nodes !!!!

And using a bounding box filter the size and

coordinates of two lungs were found.

Using a number of ITK segmentation filters, the part of CT in which we are interstead (in this special case) have been segmented.

Original CT


Conclusion and perspectivesConclusion and perspectives

Concentrate the nodes inside the region of interest

Find the right components of the registration framework,

and optimize the parameters

Applying the DVFs for remapping the calculated partial

dose of different phases to the reference phase


1) M. Varasteh Anvar, et al “Feasibility studies for the use of 2D MatriXX for quality assurance in proton and ion spot scanning beams at CNAO”PTCOG 53 – 2014 – Shanghai

2) M. Varasteh Anvar, et al “Verification of the dose distributions delivered with CNAO ion beams using the 2D MatriXX dosimeter”XCIX SIF Conference – 2013 – Trieste, Italy

3) L. K. Fanola Guarachi, F. Fausti, F. Marchetto, S. Giordanengo, G. Mazza, M. Varasteh Anvar, et al “Development of a Front-End Electronics for an Innovative Monitor Chamber for High-Intensity Charged Particle Beams”21st IEEE - 2014 – USA

4) S. Giordanengo, G. Russo, R. Cirio, M. Donetti, M. A. Garella, M. A. Hosseini, F. Marchetto, S. Molinelli, V. Monaco, R.Sacchi, M. Varasteh Anvar, et al “A DOSE-RATE APPROACH TO EVALUATE THE DOSE DELIVERED WITH THE ION PENCIL BEAM SCANNING TECHNIQUE”PTCOG 53 – 2014 – Shanghai

5) S. Giordanengo, G. Russo, F. Marchetto, V. Monaco, A. Pella, M. Varasteh, et al “Development of a GPU-based dose delivery system for adaptive pencil beam scanning”56th AAPM annual meeting and exhibition – 2014 – USA

6) S. Giordanengo, A. Attili, G. Russo, A. Vignati, M. Varasteh, et al “On-line forward planning integrated in a dose delivery system for scanningion beams”PTCOG 54 – 2015 – San Diego, California

Conference PapersConference Papers

Thanks for your attention


Suggestions: Suggestions:

A 4D dose computation method to investigate motion interplay effects in scanned ion beam prostate therapyF. Ammazzalorso - University of MarburgPhysics in Medicine and BiologyVolume 59, Issue 11, 7 June 2014, Pages N91-N99

Dosimetric consequences of intrafraction prostate motion in scanned ion beam radiotherapyF. Ammazzalorso (DKFZ)HeidelbergRadiotherapy and OncologyVolume 112, Issue 1, 1 July 2014, Pages 100-105

GPU-accelerated automatic identification of robust beam setups for proton and carbon-ion radiotherapyF. AmmzzalorsoJournal of Physics: Conference SeriesVolume 489, Issue 1, 2014, Article number 012043


The planned dose is calculated on a single image of the patient (reference CT)

The dose delivered to patient is investigated on a 4DCT which entails different respiration phases

Phase 1Phase 2

Phase 3

Phase 10

. . . .

From where this possible difference is coming?!From where this possible difference is coming?!

38

Flow chart of the Forward planning computation Flow chart of the Forward planning computation

Build rays Build rays

RayTracingRayTracing

WEPL (1D Interpol)WEPL (1D Interpol)

3D LUT Interpolation to extract the dose for each

voxel

3D LUT Interpolation to extract the dose for each

voxel

CPUCPU GPUGPU

Computing Grid creationComputing Grid creation

Select voxels within a cut-off to take into account

Select voxels within a cut-off to take into account

Voxels grid

Computational-grid points that are closer to the ray

Create a specific 3D beam LUT from existing LookUpTable, to hold the Dose per unit fluence for each voxels.

Create a specific 3D beam LUT from existing LookUpTable, to hold the Dose per unit fluence for each voxels.

Scanning magnets

Synchrotron

Linac Carbon source

Proton source

Monitorsystem

x

En

y

Protons,Carbon ions


40

Correction of carbon ion beam pattern (position):

If we compute the delta between each two nearby X, it is not equal to 2mm(step). So we need to correct the result of measurement. From simulation we have Xb.p.computed and deltaXcog.simu. (delta between computed and generated Xb.p. which is the correction!) in two columns.Now using data from MatriXX measurement (Xcog.meas. which would be modified by an equation) and above data we do an interpolation and will correct the mesurements result.



….….

The simulation was done by generating 100x100 points in the square defined by 4 adjacent chambers. The beam was described by a bi-Gaussian distribution with equal width in both directions. The signal in a given chamber was computed by considering the overlap of the beam with the chamber itself. Finally the centers-of-gravity of the signals, along X and Y, were computed and compared to the generated ones.


Transform represents the mapping of points

Interpolator: to evaluate moving image intensities at non-grid positions

Metric: how well the fixed image is matched by the transformed moving image

43

Result before perturbing the signals Result before perturbing the signals

MMM27 January 2014

(Xbp, Ybp) = (121.9, 121.9) mm

(Xbp, Ybp) = (121.9, 124.9) mm

Looking for electronic noise (background noise) I found out that it is almost rare so we forgot about it.

• 10000 points

• (Xbp, Ybp)

• G(Xm, Ym) , FWHM = 12mm

• ∑G(Xm, Ym) proportional to charge collected by each pixel

• eventually 32*32 array

44

Finding displacement of the beam by St. Dev.Finding displacement of the beam by St. Dev.

MMM27 January 2014

Since St. Dev. is very small we did not perturb the signals using St. Dev.

Correspond to spots which has two snaps

45 MMM27 January 2014

Finding displacement of the beam by Abs. Diff. vs DenominatorFinding displacement of the beam by Abs. Diff. vs Denominator

46

Finding displacement of the beam by Abs. Diff. vs DenominatorFinding displacement of the beam by Abs. Diff. vs Denominator

MMM27 January 2014

Denom

Abs. Diff.


(Xbp, Ybp) = (121.9, 121.9) mm (Xbp, Ybp) = (121.9, 124.9) mm


Third possibility is beam movement in x directionThird possibility is beam movement in x direction

ii_max

j; fix

Positive sign is for i > i_maxNegative sign is for i <= i_max


(Xbp, Ybp) = (121.9, 121.9) mm (Xbp, Ybp) = (121.9, 124.9) mm

supervisor: dr. vincenzo monacodottorato.ph.unito.it/studenti/pretesi/xxviii/varasteh.pdf ·...

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