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Page 1: Data acquisition system for a proton imaging apparatus

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Data acquisition system for a proton imaging apparatus

V.Sipalaa,b, D.LoPrestia,b, N.Randazzob, M.Bruzzid,e, D.Menichellie,d, C.Civininid, M. Brianzid, M.Bucciolinic,d, C.Talamontic,d, M.Tesie, L.Marrazzoc,d, L.Capinerif,

S.Valentinid,f G.Cuttoneg, G.A.P.Cirroneg, G.Candianog, E.Mazzagliag

a) Dipartimento di Fisica, Università degli Studi di Catania

b) INFN, sezione di Catania

c) Dipartimento di Fisiopatologia Clinica, Università degli Studi di Firenze

d) INFN, sezione di Firenze

e) Dipartimento di Energetica, Università degli Studi di Firenze

f) Dipartimento di Elettronica e Telecomunicazioni, Università degli Studi di Firenze

g) Laboratori Nazionali del Sud-INFN, Catania.

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Outline Proton therapy and proton imaging Proton imaging apparatus Data acquisition system

Tracker Single module architecture Detector VLSI front-end

Calorimeter Crystal YAG:Ce Electronic readout Trigger system

First results with proton beam Conclusions

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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 conform to the target volume.

The Bragg peak shape ensures that healthy tissues in front of and beyond the tumor are not damaged.

Through the weighted superposition of proton beams of different energies it is possible to deposit a homogenous dose in the target region using only a single proton beam direction. (Spread Out Bragg Peak -SOBP).

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photons and protons are a different interaction with the matter

proton Computed Tomography – pCTProton imaging

Main issues in the quality of treatment in proton therapy are: Patient positioning Dose planning

Actually X-rays radiography and X-CT are used but…

By the pCT it’s possible to obtain: Directly measurements of the stopping power distribution using

the same therapeutic beam In a single phase the patient positioning and the treatment

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pCT parameters

PARAMETER VALUE

Proton beam energy 250-270MeV

Proton beam rate 1MHz

Spatial resolution <1mm

Electronic density resolution <1%

Detector radiation hardness > 1000 Gy

Dose per scan < 5 cGy

Critical parameters: Proton beam rate Data acquisition system Spatial resolution Multiple Coulomb Scattering

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Reconstruct principle: Most Likely Path

A: Only entry position & direction known: straight line LB: 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

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proton Computed Tomography concept

Reveal the trace of the single proton using a silicon telescope

Measure the residual energy of the proton using a calorimeter

Reconstruct the most likely path of the single proton

Reconstruct the imagine

Calorimeter

Silicon Telescope

Silicon Telescope

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Validation of semi-analytical algorithms with pre-existing dataData acquired at LLUMC Proton beam 201MeV

Silicon tracker UCSC CsI(Tl) calorimeter

Reconstructed on p5Acquired on p4Acquired on p5

C. Talamonti et al., "Proton Radiography for clinical applications," NIM A, in press.

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4 x-y TRACKER MODULES

1 CALORIMETER

Proton imaging apparatusFirst step in the realization of pCT device

Entry and Exit

position and direction

Residual Energy

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Data acquisition system

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Single Tracker Module

Front-end board

Digital board

Detector location

Detector board with a detector and 8 chips containing the electronic front-end.

1 x-y plane consists of 2 single tracker modules1 x-y plane consists of 2 single tracker modules

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Tracker module architecture

14/3/2009

To achieve a read-out rate of 1MHz 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 used both for data transfer to the central acquisition PC and to control the tracker module DAQ parameters

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Detector Description

53 mm x 53 mm n-type substrate with p-type

implants 200 μm thickness 256 strips, each 57 μm thick 200 μm pitch Integrated resistance for bias

1.5MOhm

Bias ring

AC PADDC PAD

Substrate bias PAD Guard ring

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VLSI front-end description AMS 0.35u CMOS Technologie

1.6 mm x 6 mm

32 channels

Power dissipation = 14,5 mW @ chan

Vcc = +3.3 V

Charge Sensitive Amplifier

Differentiator

(high pass)

Integrator

(low pass)

Comparator Buffer

External threshold voltage

OUT

Single strip

Single channel

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Calorimeter

YAG:Ce propertiesYAG: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 @100MeV

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Calorimeter readout & Trigger generator board

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Tracker module test

First results of the beam test at

Laboratori Nazionali del Sud with 62MeV protons

New calibration

Test with beta source

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Tracker module: 62MeV proton beam at Laboratori Nazionali del Sud (LNS)

0 20 40 60 80 100

50

100

150

200

250

Time over Threshold (x10ns)

counts

Vth=1.80VVth=1.90VVth=2.00V

0 10 20 30 40 50 600

10

20

30

40

50

position (mm)

counts

Vth=1.90VVth=2.00V

Front-end board and digital board : beam profile Time Over Threshold for different threshold voltage

A threshold voltage value for all chips

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Efficiency of all channels vs input charge for fixed threshold voltage: ΔVth=0

Efficiency of all channels vs threshold voltage for fixed input signal: Q= 5MIP

Single tracker module:New calibration with a threshold voltage value for each chip

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T(Q) calibration curves: Duration pulse vs input equivalent charge

Single tracker module:New calibration with a threshold voltage value for each chip

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Single tracker module: Test with beta source 90Sr

Acquisition rate = 20kHz Total counts =100000 events

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Calorimeter test

Linearity study

Homogeneity study

New electronic readout

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Calorimeter: beam test -Loma Linda Medical Center Charge spectrum at different proton energies

0 200 400 600 800 10000,0

0,2

0,4

0,6

0,8

1,0

No

rma

lize

d c

ou

nts

Channel

Ein 35MeV Ein 100MeV Ein 200MeV

0 200 400 600 800 10000,0

0,2

0,4

0,6

0,8

1,0

No

rma

lize

d C

ou

nts

Channel

Ein 35MeV Ein 100MeV Ein 200MeV

0 200 400 600 800 10000,0

0,2

0,4

0,6

0,8

1,0

No

rmal

ized

Co

un

ts

Channel

Ein 35MeV Ein 100MeV Ein 200MeV

0 200 400 600 800 10000,0

0,2

0,4

0,6

0,8

1,0

No

rma

lize

d C

ou

nts

Channel

Ein 35MeV Ein 100MeV Ein 200MeV

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Calorimeter: beam test -Loma Linda Medical Center

Linearity ( 30-200MeV energy proton range )

0 50 100 150 2000

100

200

300

400

500

600

Pe

ak

po

sit

ion

Ein [MeV]

data linear fit

Y = -53,69 + 2,83 XLinearity 2,7%

0 50 100 150 2000

100

200

300

400

500

600

Pea

k P

osi

tio

n

Ein [MeV]

data linear fit

Y = -62,12 + 2,87 XLinearity 3,3%

0 50 100 150 2000

100

200

300

400

500

600

700

800

900

Pe

ak

po

sit

ion

Ein [MeV]

data linear fit

Y= -91,28 + 4,5 X Linearity 2,2%

0 50 100 150 200

0

100

200

300

400

500

600

700

Pea

k p

osi

tio

n

Ein [MeV]

data linear fit

Y = -84,63 + 3,69 XLinearity 2,9%

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Calorimeter: beam test -Loma Linda Medical CenterSingle crystal homogeneity study

60mm

60m

m

The tracker area has been divided into 30x30 squares (area = 2x2mm2). For each square the charge spectrum has been made.

This is the map of the charge spectrum peak value

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Calorimeter: New electronic readout Yesterday

CR110 + CR220-3us

Today

Low acquisition rate High acquisition rate

Bassini, Boiano and Pullia IEEE TNS, VOL. 49, NO. 5, OCTOBER 2002

Test with YAG:Ce in October ‘09

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ConclusionsA proton imaging device is being built by the Italian collaborationA proton imaging device is being built by the Italian collaboration Tracker

Single module: assembled and tested at LNS with 62MeV proton beam Calorimeter

YAG calorimeter: completely characterized at LLMC with 30-200MeV proton beam

Front-end electronics: prototype exists (commercial parts) Trigger generator assembled

Future plansFuture plans Calorimeter with new front-end (higher rate): to be tested with proton beam (by the

end of 2009) Two tracker modules (one x-y plan) and the calorimeter: to be tested with proton

beam (by the end of 2009) Complete device built (by the end of 2010)