Patent ID: 11877828
Assignee: THE GOVERNING COUNCIL OF THE UNIVERSITY OF TORONTO
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 17:
18. A differential photoacoustic intravascular imaging system, comprising:
a light source for generating first optical energy within a first wavelength band and second optical energy within a second wavelength band;
modulating means for modulating the first optical energy and the second optical energy to obtain first modulated optical energy and second modulated optical energy, respectively, such that the first modulated optical energy and the second modulated optical energy are respectively modulated, out of phase, based on a reference waveform having a chirped temporal profile;
an ultrasound transducer; and
control and image processing circuitry operably connected to the ultrasound transducer and the modulating means, the control and image processing circuitry comprising a processor and a memory, the memory comprising instructions executable by the processor for performing steps comprising:
performing a first calibration to reduce radio frequency noise by:
processing first signals obtained from an ultrasound transducer to generate first calibration image data, wherein the first signals are processed by performing, in the frequency domain, cross-correlation between the first signals and the reference waveform; and
controlling a relative modulation amplitude and a relative modulation phase of electrical signals employed for modulation of the first modulated optical energy and the second modulated optical energy to reduce radio frequency noise in the first calibration image data; and

performing a second calibration to facilitate differential photoacoustic detection by:
directing the first modulated optical energy and the second modulated optical energy onto a region of a subject;
detecting photoacoustic energy responsively generated due to absorption of the first modulated optical energy and the second modulated optical energy, thereby obtaining photoacoustic signals, and processing the photoacoustic signals to generate second calibration image data;
wherein the photoacoustic signals are processed by performing, in the frequency domain, cross-correlation between the photoacoustic signals and the reference waveform; and
tuning a relative intensity of the first modulated optical energy and the second modulated optical energy, in the absence of varying the relative modulation amplitude and relative modulation phase of the electrical signals employed for modulation of the first modulated optical energy and the second modulated optical energy, to reduce photoacoustic image artefacts in the second calibration image data, wherein the photoacoustic image artefacts are associated with a material intended to be suppressed via differential optical excitation.