The Magic Cube and the Pixel Ionization Chamber: detectors for monitor and dosimetry of radiotherapy beams

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The Magic Cube and the Pixel Ionization Chamber
detectors for monitor anddosimetry of
radiotherapy beams

• S. Amerio1, A. Boriano2 , F. Bourhaleb2,3 , R.
  Cirio2 , M. Donetti2,3,
• E. Garelli2,4 , S. Giordanengo2, E. Madon5 , F.
  Marchetto2 , U. Nastasi1 ,
• C. Peroni2 , C. J. Sanz Freire2, A. Sardo5, E.
  Trevisiol5
• 1 Ospedale S. Giovanni A. S., Torino 
• 2 Universiy and INFN, Torino
• 3 Fondazione TERA, Novara
• 4 A.S.P. , Torino
• 5 O.I.R.M. S. Anna, Torino

? Partially financed by IBA, Ion Beam
Application, Louvain-la-Neuve(Belgium)
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Highly conformal radiotherapy

• GOAL
• use radiation to
• kill cancer cells and spare healthy tissue

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Hadron radiotherapy

• Uses (mainly, nowadays) protons and carbon ions
• Good for specific diseases
• 1 of total
• It is becoming hospital based

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Photon radiotherapy (IMRT)

• Intensity Modulated RadioTherapy
• State-of-the-art
• Uses photons obtained with e- linear accelerators
• Specific diseases
• Has become very popular
• Still not very widespread due to verification
  problems

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The Magic Cube

• A tool for verification of hadrontherapy
  treatment plan in reasonably short time (1-2
  minutes)
• Sampling calorimeter with strip ionization
  chambers
• VLSI electronics readout

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In the beginning
Strip ionization chambers (6 for X-view 6 for
Y-view)

• At GSI Darmstadt

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One of the chambers

• 64 strips
• 4 mm wide
• 24 cm long
• 24x24 cm2 active
• area

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The VLSI chip

• 64 channels
• AMS 0.8 mm CMOS
• 16 bit output
• Recycling integrator

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VLSI block diagram
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A simple beam (X-view)
beam direction

• At CPO Orsay

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A Carbon Bragg peak
beam direction

• 270 MeV/u 12C at GSI Darmstadt

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The Cube on tour
GSI Darmstadt C synchrotron
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PSI Villigen p synchrotron
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CPO Orsay p cyclotron
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Commercial version sold to Loma Linda University
Medical Center and Ion Beam Application
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The Pixel Chamber

• 1024 pixels
• 7.5 mm wide
• 24x24 cm2 active area

• The aim lets go real 3D

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Precision in the reconstruction of the center of
gravity of a C beam
Vertical axis
Horizontal axis
?lt0.08 mm
?lt0.13 mm
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Dedicated to photons

• No inhomogeneities
• Careful shielding

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A calibration with 24x24 cm26 MV photon beam
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Breast cancer treatment
Dynamic MultiLeaf Collimator
Treatment verification
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Treatment plan (simulation) vs. measurement
with pixel chamber
Pixel chamber
Treatment plan
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A closer look
j
j
Pixel chamber
Treatment plan
i
i
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Nowadays things are moving

• Intensity Modulated RadioTherapy (IMRT)

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Measuring DURING treatment
Deposited dose as function of time
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Research ? Industry

• The VLSI chip produced and used by IBA and
  Wellhofer/Scanditronix

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Research ? Industry

• Pixel and strip chambers during a test at IBA

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Research ? Industry

• Dose deposition with the new IBA raster scan as
  measured with the pixel chamber

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Conclusions

• HEP techniques may be extremely interesting for
  medical applications

• Magic Cube, TERA VLSI and Pixel Chamber have
  fulfilled the design requirements
• Industry has taken advantage of these
  University/INFN driven projects

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The VLSI and radiation damage

• 30 kV photons

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The VLSI and radiation damage

• Legnaro fast neutrons

_at_5x1012still OK
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Fast data acquisition

• Real time OS
• 1024 channels readout in 100 ms

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Slow data acquisition

• National Instruments I/O board
• Labview on PC
• 1024 channels readout in 500 ms

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Chamber layout
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Using a raster scan (GSI test)
Target contour
Energy deposit
Voxel
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Test al GSI (Darmstadt) ioni carbonio

• Caratterstiche del fascio
• Irraggiamento di tipo raster-scan
• C6, dimensioni del fascio 8.8 mm (FWHM)

• Obiettivi
• Risoluzione spaziale
• Omogeneità della risposta
• Acquisizione dati sincronizzata con il
  raster-scan
• Test sistema monitor di fascio

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Arc 7
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