Development of a tomographic system for online dose ...scoccola/iguazu/NPA/04_NPA4-Minsky.pdf · 3 VI Latin American Symp. on Nuc. Phys. and Applications Development of a tomographic

1

Development of a tomographic system for online dose

measurements in BNCTMinsky D.M.1,2, Valda A.A. 1,2, Burlon A.A. 1,2,3, Kreiner A.J. 1,2,4 y Somacal H. 1,2

1. Departamento de Física (CAC, CNEA) 2. Escuela de Ciencia y Tecnología (UNSAM)

3. Fundación J.B. Sauberán4. CONICET

2

VI Latin American Symp. on Nuc. Phys. and Applications Development of a tomographic system for online dose measurements in BNCT

Epithermalneutrons

Figure adapted from:http://web.mit.edu/nrl/www/bnct/info/description/description.html

[ ][ ] 1:4

ssueHealthy ti BTumor B

10

10≈

3


10BThermalneutron

10B + n → 11B*→ 7Li* + 4He

7Li(0.84 MeV)

4He(1.47 MeV)

γ (478 keV)

5 µm

9 µm

↓ t ~ 10-14 s

Li + γ (478 keV)


γ-ray Telescope SystemNetherlands Energy Research Foundation, Petten, The NetherlandsEindhoven University of Technology, Eindhoven, The NetherlandsNuclear Research and Consultancy Group, Petten, The Netherlands

WFAR Verbakel, F Stecher-Rasmussen, Nucl. Instr. and Meth. in Phys. Res. A, 394, 163-172, 1997.WFAR Verbakel, W Sauerwein, K Hideghety, F Stecher-Rasmussen, Int. J. Radiation Oncology Biol. Phys. 55(3), 743–756, 2003.

Related works: γ-ray telescopeand PG-SPECT

PG-SPECT (Prompt Gamma-ray SPECT)Research Reactor Institute, Kyoto University, JapanResearch Institute for Radiation Biology and Medicine, Hiroshima Univ., Japan

T Kobayashi, Y Sakurai, M Ishikawa, Med. Phys. 27(9), 2124-2132, 2000.

4



Collimator design

Requirements:• Trans-septal penetration

less than 6%• Spatial resolution 1cm

at 20 cm from detector

Results:• t=2 mm• ∅=4.4 mm• e=80 mm

e

t∅

Collimator thickness

Geo

met

rical

effic

ienc

y[%

]

Collimator Thickness (e) [mm]

Geo

met

rical

effic

ienc

y[%

]

Spatial Resolution [mm]

5



System numerical simulation

• System matrix (influence of each pixel on each detector for every projection).

MonteCarlo simulation with MCNP-4C of:

Some data of the simulations:

• Image consisting in 21*21 pixels• Pixels of 1cm*1cm size• 37 detectors in each projection• 20 projections regularly spaced

by 9O

6


P1 P2 P3 P4

P5 P6 P7 P8

P9 P10 P11 P12

P13 P14 P15 P16

B6

B7

B8

B9

B10

B1 B2 B3 B4 B5

System matrix calculation


…………

…m34m32m31

…m23m22m21

…m13m12m11

…

p3

p2

p1

…

b3

b2

b1

=.


7


………

…m34m32

…m23m22

…m13m12

…

0

0

1

…

b3-1

b2-1

b1-1

=.

…

m31

m21

m11

…

b3-1

b2-1

b1-1



……...

…m34b1-2

…m23b1-2

…m13b1-1

…

0

1

0

=.

…

m33

m23

m12

…

b3-2

b2-2

b1-2

…

b3-2

b2-2

b1-2


8



Phantoms numerical simulations

9


WithoutBackground

→→→→

→→→→

↑↑↑↑Simulatedsource

↑↑↑↑Simulatedsinogram

↑↑↑↑Reconstructed

image

Numerical simulations of phantoms

WithBackground


Influence of statistical fluctuations

10


Influence of tumor size


11


TANDARLaboratory


Previous experimental measurements

12


Experimental setup under characterization


13


Conclusions and future work

• A tomographic SPECT system for online dose measurements in BNCT have been designed

• The whole system has been simulated by means of MonteCarlo calculations

• Sinograms from numerical phantoms have been simulated and used for image reconstruction

• Statistical fluctuations must be kept under 3-5%• The influence of the image reconstruction algorithm on

quantitative concentration measurements will be studied• The experimental setup is under characterization and

images will be acquired in the near future

Documents

Development of a tomographic system for online dose ...scoccola/iguazu/NPA/04_NPA4-Minsky.pdf · 3 VI Latin American Symp. on Nuc. Phys. and Applications Development of a tomographic