photoacoustic mammography: the development of pam2 · pam1 how important illumination is to avoid...

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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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