photoacoustic mammography: the development of pam2 · pam1 how important illumination is to avoid...
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Photoacoustic Mammography: the development of PAM2 Daniele Piras1, Wenfeng Xia1, Michelle Heijblom1,2, Johan van Hespen1, Ton van Leeuwen1,3, Wiendelt Steenbergen1 and
Srirang Manohar1. 1Biomedical Photonic Imaging Group, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
2 Center for Breast Care, Medisch Spectrum Twente, Enschede, The Netherlands 3 Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
Starting point – PAM1
Goals
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ase 1
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Ph
ase 1
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1 MHz, unfocused transducer, 590 elements (2x2mm2) 1064 nm, 10 ns pulses, 10 Hz;
Phase 1:
Tandem scan 30mJ/cm2; Øbeam=1.6 cm; 4x4cm2 scan
Phase 1b:
Steady scan 10mJ/cm2; Øbeam=7cm; 4x4cm2 scan
Phase 2:
Steady scan 10mJ/cm2; Øbeam=7cm; 9x8cm2 scan
RESULTS: from Phase 1 to Phase 2 we reduced the optical and acoustical limited view problem BUT PAM1 planar geometry is still not suitable for full breast examination
• full-field CT photoacoustic mammography without compression
• wavelength where tumor has highest contrast
• speed-of-sound and acoustic attenuation imaging
• clinical investigation
• development of a custom-designed ultrasound detector
• full breast imaging in less than 10 minutes.
• detector optimization implies low NEP
• 360° CT will give optimum resolution higher than finite planar aperture situation
• CT permits Hybrid imaging
• measure area close to chest wall, and a wide range of breast sizes
• measure non-palpable lesions
• breast to be uncompressed
• … comfort, easy maintenance, easy accessibility…
Advantages Requirements
PA
M 2
Investigation on CT configurations
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CT – tandem
1 source
CT – multiple
sources
CT – top
illumination
• tandem illumination does not work
• multiple illumination better in middle/side areas
• top illumination better in middle/central areas
• integration of top illumination and fiber illumination
Design of the new instrument
bottom illumination
Fiber illumination
Full simulation of PAM2 geometry
Fluence distribution for
bottom illumination
Fluence distribution for
bottom and side illumination
Spherical absorbing
targets
Detection geometry
(10 rotation, 2.7degrees)
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Simulations show that
the proposed
geometrical CT
configuration works
We learned from
PAM1 how important
the steady illumination
is to avoid optical
limited view problem
The contribution of
side illumination is
crucial for imaging
areas close to the
chest-wall
Conclusions Layout
US module
LDS module PERPACT module
2 wavelengths:
Nd:YAG 1064nm
Alexandrite 755nm
66% bare beam
33% fiber coupled