Omnidirectional photoacoustic tomography system

Abstract

An ultrasonic photoacoustic tomography system includes a mirror arrangement configured to redirect an incoming light beam defining a central axis such that the mirror arrangement reflects the incoming light beam to form a converging ring-shaped light beam. This converging ring-shaped light beam directs light originating from the incoming light beam radially inward covering a 360° circumferential range around the central axis. A closed-geometry acoustic detector is configured to pick up reactive sound waves from tissue irradiated by the converging ring-shaped light beam over the 360° circumferential range.

1 . A photoacoustic tomography system comprising
 a mirror arrangement configured to redirect an incoming light beam defining a central axis, the mirror arrangement reflecting the incoming light beam to form a converging ring-shaped light beam, which directs light originating from the incoming light beam radially inward covering a 360° circumferential range around the central axis, and   a closed-geometry acoustic detector configured to pick up reactive sound waves an object irradiated by the converging ring-shaped light beam over the 360° circumferential range.   
     
     
         2 . The photoacoustic tomography system of  claim 1 , wherein both the converging ring-shaped light beam and the acoustic detector are configured to be movable along the central axis. 
     
     
         3 . The photoacoustic tomography system of  claim 1 , wherein the mirror arrangement includes at least a first mirror with a first mirror surface being cone-shaped, a second mirror being ring-shaped with a second mirror surface forming a hollow truncated cone, and a third mirror being ring-shaped with a third mirror surface forming a hollow truncated cone, wherein the first, second, and third mirrors are arranged coaxially with the central axis. 
     
     
         4 . The photoacoustic tomography system of  claim 3 , further comprising a mounting platform that is transparent for a wavelength bandwidth of the incoming light beam, the mounting platform holding the first mirror. 
     
     
         5 . The photoacoustic tomography system of  claim 4 , wherein the mounting platform extends in a radial plane and also holds the second mirror. 
     
     
         6 . The photoacoustic tomography system of  claim 5 , wherein the mounting platform is positioned between the second mirror and the third mirror. 
     
     
         7 . The photoacoustic tomography system of  claim 4 , wherein the mounting platform, the first mirror, and the second mirror are in a fixed relationship relative to one another and the third mirror is axially movable relative to the mounting platform, the first mirror, and the second mirror. 
     
     
         8 . The photoacoustic tomography system of  claim 7 , wherein the closed-geometry acoustic detector is axially movable relative to the mounting platform, the first mirror, and the second mirror. 
     
     
         9 . The photoacoustic tomography system of  claim 8 , wherein the closed-geometry acoustic detector is coupled to the third mirror and movable therewith. 
     
     
         10 . The photoacoustic tomography system of  claim 9 , further comprising a drive mechanism configured for driving the acoustic detector and the third mirror along the central axis. 
     
     
         11 . The photoacoustic tomography system of  claim 7 , further including an adjustment mechanism for axially guiding the third mirror, the adjustment mechanism being held by the mounting platform. 
     
     
         12 . The photoacoustic tomography system of  claim 3 , wherein the acoustic detector and the third mirror have a central opening with a diameter of at least 150 mm. 
     
     
         13 . The photoacoustic tomography system of  claim 3 , wherein the first mirror surface has an apex configured to face the incoming light beam and to reflect the incoming light beam radially outward over the 360° circumferential range, the second mirror surface having an angle relative to the central axis configured to reflect the radially outward reflected light beam axially away from the incoming light beam, and the third mirror surface having an angle relative to the central axis configured to reflect the axially reflected light beam radially inward to form the converging ring-shaped light beam, wherein the radially inward reflected light beam encloses an angle of 30° to 80° with the incoming beam. 
     
     
         14 . The photoacoustic tomography system of  claim 13 , wherein the third mirror surface is arranged at an angle relative to the central axis configured to redirect the axially reflected light beam toward an axial location on a surface of the irradiated object, the axial location overlapping with an axial position of the closed-geometry acoustic detector. 
     
     
         15 . The photoacoustic tomography system of  claim 3 , wherein the first mirror surface, the second mirror surface, and the third mirror surface are first-surface mirror surfaces. 
     
     
         16 . The photoacoustic tomography system of  claim 1 , further comprising an ultrasound source and ultrasound detector configured to determine a distance of a surface of the irradiated object from the central axis. 
     
     
         17 . The photoacoustic tomography system of  claim 16 , wherein the photoacoustic tomography system is configured for performing an automatic scanning procedure by a adjusting a light intensity of the incoming beam based on the determined distance. 
     
     
         18 . The photoacoustic tomography system of  claim 16 , wherein the ultrasound detector is formed by the closed-geometry acoustic detector. 
     
     
         19 . The photoacoustic tomography system of  claim 1 , further comprising a light source producing a dimmable collated light beam. 
     
     
         20 . The photoacoustic tomography system of  claim 1 , further comprising:
 an ultrasound source and ultrasound detector configured to determine an acoustic heterogeneity of the irradiated object; and   a processor configured to process reconstruction algorithms to compensate amplitudes of the detected reactive sound waves for the acoustic heterogeneity of the irradiated object.