proton computed tomography - fisica medica · proton computed radiography ... 200 µµµµm...

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Associazione Italiana di Fisica Medica

Centro di Cultura Scientifica “A. Volta”

Scuola Superiore di Fisica in Medicina “P. Caldirola”(Direttore: M. Stasi)

LE NUOVE FRONTIERE DELLA TECNOLOGIA IN DIAGNOSTICA E TERAPIA:

DALLA FISICA ALLA MEDICINA

Roma, 27 Giugno 2013

Responsabili Scientifici: M.D. Falco, A. Soriani Coordinatore Scientifico: M Tavolozza

Sezione di Catania

[email protected], 27 2013 Fondazione PTV- Policlinico Tor Vergata

PROTON COMPUTED TOMOGRAPHY (PRIMA PROJECT)

M. Bruzzia,b, M. Bucciolinib,c, M. Carpinellig,h, G. A. P. Cirroned, C. Civininib, G. Cuttoned, D. Lo Prestie,f, S. Pallottab,c, C. Pugliattie,f, N. Randazzof, M. Scaringellaa,b, V. Sipalag,h, C. Stancampianoe,f C. Talamontib,c, M. Tesia, E. Vanzic, M. Zanib,c

a) Dipartimento di Energetica, Università degli Studi di Firenze, via S. Marta 3, 50139 Firenze.

b) INFN, sezione di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino (FI).

c) Dipartimento di Fisiopatologia Clinica, Università degli Studi di Firenze, Viale Pieraccini, 6, 50139 Firenze.

d) Laboratori Nazionali del Sud-INFN, via S. Sofia 62, I-95123, Catania.

e) Dipartimento di Fisica, Università degli Studi di Catania, via S. Sofia 64, I-95123, Catania.

f) INFN, sezione di Catania, via S. Sofia 64, I-95123, Catania.

g) INFN, sezione di Cagliari , S.P. Sestu, 09042 Monserrato, Cagliari.

h) Università degli Studi di Sassari, Piazza Università 21, 07100 Sassari.

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Outline

� Introduction: proton therapy and proton imaging

� Proton imaging apparatus

� Proton Radiographies and Tomography at 60MeV

� Upgrade of apparatus

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Proton therapy

The proton therapy is a good clinical treatment for cancer as it permits to obtain a

dose distribution extremely conformed to the target volume.

The protons with penetration depth havea well-defined dose maximum (Braggpeak) that follows a relatively lowentrance dose region. Beyond the Braggpeak the dose fall-off is very steep (from90% to 20% of the peak dose within a fewmillimiters)

Through the weighted superposition ofproton beams of different energies it ispossible to deposit a homogenous dosein the target region using only a singleproton beam direction.(Spread Out Bragg Peak -SOBP).

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pCT proposal in 1976 by Allan Cormack Published on J. of Appl. Phys.

proton imaging idea

“the dose required for proton scans is five to ten times less than for X-Ray

scans for the same amount of information”

“due to the different mechanism of interaction with matter one ought to see

different things using different radiations”

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proton Computed Tomography: why?

In proton therapy treatments it is important to know:

Patient positioning:

Currently performed using X-rays radiography and tomography in aprevious phase

pCT allows better accuracy and

single phase positioning / treatments

Dose Calculation:

Currently performed using X-rays computed tomography

Problem: protons and photons have

different interaction with matter

pCT uses protons directly for dose calculation

The error intrinsic in this conversion (due to µ(ηe,Z) dependency on atomic number and electron density) is the

principal cause of proton range indetermination (3%, up to 10 mm in the head)

[Schneider U. (1994), Med Phys. 22, 353]

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International scenarioUSA competitor : Loma Linda – Santa Cruz – NUI – Fermilab

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Single particle tracking and Most Likely Path reconstruction

• A: Only entry position & direction known: straight line L

• B: Entry position & direction + exit position known: straight line L’

• C: Entry position & direction + exit position & direction known: curved path L’’, “banana-shaped”, narrow confidence limits

L’’’’ L’’’’’’’’L

B CA

in

out

E

EL

eES

dEKrdr

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Calorimeter

Silicon Telescope

Silicon Telescope

proton Computed Radiography

� Reveal the trace of the single protonusing a silicon telescope

� Measure the residual energy of theproton using a calorimeter

� Reconstruct the most likely path ofthe single proton

proton Computed Tomography

� pCR for different projections with arotating gantry

� Reconstruct the image

Concept8

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Parameters of pCT9

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PROGRAM

− Manufacture a high-performance prototype for proton radiography.− Develop suitable imaging algorithms:

- analysis of data;- MC simulations.

− Validate the pCR system with pre-clinical studies− Conceive a configuration for a pCT system:

- Hardware and data acquisition;- Reconstruction algorithms (ART, SART...).

THE “PRoton IMAging PROJECT” pCR apparatus oriented to pCT

Cfr V. Sipala et al. Nuovo Cimento D (2011)

V. Sipala et al., Nucl. Instr. and Meth. A 612 (2010) 566–570

V. Sipala et al. Nuclear Physics B, Vol. 197, Issue 1(2009) 39-42

C. Talamonti et al., Nucl. Instr. and Meth. A. 612 (2010) 571

C. Civinini et al., Nucl. Instr. and Meth. A 623 (2010) Pages 588-590

G.A.P. Cirrone et al., NIM A, vol. 576, no. 1, 11 June 2007, pp. 194-197.

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Schema of Proton Computed Radiography Device by the PRIMA (PRoton IMAging) collaboration

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Proton beam

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Single module architecture

• To achieve a read-out rate of 1 MHz a fully parallel digital strip readout system has been developed

• Eight 32-channel VLSI front-end chips acquire the detector signals and sends data in parallel to an FPGA (Xlinx Spartan-3AN) which performs zero suppression and moves data to a buffer memory (~5x105 events).

• An Ethernet commercial module is use both for data transfer to the central acquisition PC and to control the tracker module DAQ parameters

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Silicon strip detector

Manufactured by Hamamatsu Photonics

53x53 mm2

p+-on-n strips

256 ch, 200 µµµµm pitch

200 µµµµm thickness(To reduce the multiple scattering

in the detector planes while keeping

a good sensitivity to protons)

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VLSI front-end

• AMS 0.35u CMOS Technology

• 1.6 mm x 6 mm

• 32 channels

• Power dissipation = 14,5 mW @ chan

• Vcc = +3.3 V

Test performed at LNS with 60MeV proton beam

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Calorimeter

YAG:Ce propertiesPHYSICAL PROPERTIES

Density [g/cm3] 4.57

Hygroscopic No

Chemical formula Y3Al5O12

LUMINESCENCE PROPERTIES

Wavelength of max. emission [nm] 550

Decay constant [ns] 70

Photon yield at 300k [103 Ph/MeV] 40-50

• 4 YAG:Ce scintillating crystals

Each crystal 30 x 30 mm2 x 100mm

• 4 Photodiode 18 mm x 18 mm

• 4 commercial front-end(Charge Sensitive Amplifier & shaper )

Charge spectrum @100MeV15

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pCR : full integration16

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Profile along diagonal holes

• One cluster in each plane

• Cut on the difference between the

“entrance“ and “exit” angle

Test beam at LNS - 62 Mev protons radiography

P1 P2 P3 P4

Beam pipe

Sigma=0.170 ± 0.09 mmFWHM = 0.400± 0.212 mm

Re

sid

ua

l en

erg

y (

Me

V)

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First radiography ??

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Walnut radiography

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Calorimeter

Tracker: 4 x-y planes

Beam

Complete pCT apparatus Test at LNS

-Alignment test

-Radiography test

-Tomography test

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First Tomography: pCT image from LNS data20

PMMA phantom

36 projection steps: 0°� 360°An average of 950000 events per projection

E0=62MeV INFN-LNS

Filtered Back Projection algorithm

Tomographic equation (Wang, Med.Phys. 37(8), 2010: 4138)

∫∫

=

0

),(),(),,( 2020

E

EPath res

dEEOHS

EOHS

dlEyxSρρ

«projection»Unknown stopping power

distribution (at E0)

Evaluation of the “projection” term

(through numerical integration

starting from NIST tables and using

the measured Eres)

Eres Wang projection

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We defined a plane parallel to detector’s planes and passing through the phantom axis.

The plane was sampled in a 256× 256 matrix, 200 µm pixel size.

For each event, the associated projection bin was determined by the intersection of the lineconnecting P2 and P3 impact points with the plane.

Data analysis: data rebinning

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0,6

1,6

2,6

3,6

4,6

5,6

6,6

2 4 6 8 10 12

s.d

. (%

)

Order

Noise (no cut)

16/128

18/128

20/128

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

2 4 6 8 10 12

FW

HM

(m

m)

Order

Resolution (no cut)

16/128

18/128

20/128

Cut-off 20/128

Order 12

FWHM=1.0±0.03mm

Noise=1.4%

FBP filter choice

There is a trade-off between resolution and noise.

Cut-off 20/128

Order 2

FWHM=0.8±0.2mm

Noise=6.3%

Cut-off (% of Nyquist frequency = 2.5mm-1)

Cut-off 20/128

Order 4

FWHM=0.9±0.1mm

Noise=2.4%

E. Vanzi et al. The PRIMA collaboration:

preliminary results in FBP reconstruction of pCT

data –RESMDD12 Conference

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pCT image

No selection cuts has been

applied to the data sample

E. Vanzi et al. The PRIMA collaboration:

preliminary results in FBP reconstruction of pCT

data –RESMDD12 Conference

Butterworth filter: order 2,

cut-off 20/128 of the Nyquist freq.

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A system for proton radiography has been realized:� Field of view of about 5x5cm2

� Acquisition time of the order of 10sec (10kHz, 105 events)

The complete apparatus has been tested with 60MeV proton beam at LNS

FBP reconstruction methods of the proton radiography has been developed and tested with data

The tomographic data analysis is in progress

The PRIMA upgrade is defined

Future planes

� Analysis of the tomography data and development of reconstruction algorithm � New test of the apparatus at higher energy� Construction of pCT apparatus for clinical application

Today Status24

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How to move from a walnut ...E

nerg

y [MeV

]

...to a brain?

~20cm

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PRIMA Upgrade

GOAL: pCT system for clinical applications.

• Larger active area

• On line data acquisition

�Active area 5 x 20 cm2 using the 5x5cm2 detectors

�New data acquisition system

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Tracker module

BackY-Plane

• 4 detectors

• 4 Front-end data blocks

X2 F

ront-e

nd

X1

Fro

nt-e

nd

FrontX-Plane

• 4 detectors

• 2 Front-end data blocks

Sensor A1 Sensor A2 Sensor A3 Sensor A4

Y2 Front-end Y3 Front-end

Y1 Front-end Y4 Front-end

Sensor B1 Sensor B2 Sensor B3 Sensor B4

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• 32 channel discriminator; parallel read-out

• Channel-by-channel threshold setting (one DAC/ch)

• I2C for thresholds download

FE Chip

microbonded

on the tracker

board

New tracker front-end chip

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DAQ of tracker: architecture29

Central

acquisition

VIRTEX 6

CALORIMETER DAQ

Trigger

enableTrigger

7gen

SS 1

SS 6

.

.

.

256

256

SM

serial link data/clk200 Mbs

SSD 1

SSD 6

256

256

Frontend 1

Frontend 6

tracker plane

SS 1

SS 6

.

.

.

256

256

SM


SSD 1

SSD 6

256

256

Frontend 1

Frontend 6

tracker plane

SS 1

SS 6

.

.

.

256

256

SM


SSD 1

SSD 6

256

256

Frontend 1

Frontend 6

tracker plane

SS 1

SS 6

.

.

.

256

256

SM

6 readout links200(x8) Mbs each

SSD 1

SSD 6

256

256

Frontend 1

Frontend 6

tracker plane

4 readout links

200(x8) Mbs

each

• The front end of each detector will be monitored by a XilinxSpartan 6 FPGA indicated as Spartan Slave (SS)

• When a trigger occurs the corresponding SS containing at least one hit will send the data to a central FPGA indicatedas Spartan Master (SM)

• The SM will then send tha data to the central acquisitionboard

Trigger

gen

Trigger_en

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Ethernet

link

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21cm

6cm

Calorimeter Layout Single channel front-end

• 16 simultaneous 50 MS/s, 14-bit channels • 8 digital inputs • 8 digital outputs

NI 575132-Channel Digitizer Adapter Module for NDT Applications

NI PXIe-7962RNI FlexRIO FPGA Module for PXI Express

• DSP-focused Virtex-5 SX50T FPGA programmable with the LabVIEW FPGA Module

• Deployment platform for LabVIEW Real-Time and LabWindows™/CVI Real-Time applications

NI PXIe-8102 RT1.9 GHz Intel Celeron T3100 Dual Core With LabVIEW Real-Time

A0

A1|||||||||

A13

Sampling, data storage and transfer

Calorimeter Upgrade

• Sampling of 14 analog signals

• Output of trigger signal

• “Global Event Number”(GEN

output)

• Pre – elaboration data

• Trigger generator

• GEN generetor

• Data storage

• Data transfer

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7x2 YAG:Ce scintillating crystals 30 x 30 mm2 x 100mm each.

Upgraded Calorimeter Integration

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Upgraded CalorimeterLNS test beam Feb. 2013

14 channels Analog Front-end board

New DAQ based on FlexRio NI platform

Setup on CATANA facility

sampled signal

Energy spectrum 62 MeV proton beam

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Thanks for your time!!!([email protected])

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proton computed tomography - fisica medica · proton computed radiography ... 200 µµµµm...

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